functional p53 expression: Topics by Science.gov

Sample records for functional p53 expression

Gain-of-function mutant p53 but not p53 deletion promotes head and neck cancer progression in response to oncogenic K-ras

PubMed Central

Acin, Sergio; Li, Zhongyou; Mejia, Olga; Roop, Dennis R; El-Naggar, Adel K; Caulin, Carlos

2015-01-01

Mutations in p53 occur in over 50% of the human head and neck squamous cell carcinomas (SCCHN). The majority of these mutations result in the expression of mutant forms of p53, rather than deletions in the p53 gene. Some p53 mutants are associated with poor prognosis in SCCHN patients. However, the molecular mechanisms that determine the poor outcome of cancers carrying p53 mutations are unknown. Here, we generated a mouse model for SCCHN and found that activation of the endogenous p53 gain-of-function mutation p53R172H, but not deletion of p53, cooperates with oncogenic K-ras during SCCHN initiation, accelerates oral tumour growth, and promotes progression to carcinoma. Mechanistically, expression profiling of the tumours that developed in these mice and studies using cell lines derived from these tumours determined that mutant p53 induces the expression of genes involved in mitosis, including cyclin B1 and cyclin A, and accelerates entry in mitosis. Additionally, we discovered that this oncogenic function of mutant p53 was dependent on K-ras because the expression of cyclin B1 and cyclin A decreased, and entry in mitosis was delayed, after suppressing K-ras expression in oral tumour cells that express p53R172H. The presence of double-strand breaks in the tumours suggests that oncogene-dependent DNA damage resulting from K-ras activation promotes the oncogenic function of mutant p53. Accordingly, DNA damage induced by doxorubicin also induced increased expression of cyclin B1 and cyclin A in cells that express p53R172H. These findings represent strong in vivo evidence for an oncogenic function of endogenous p53 gain-of-function mutations in SCCHN and provide a mechanistic explanation for the genetic interaction between oncogenic K-ras and mutant p53. PMID:21952947
[Interaction between p53 and MDM2 in human lung cancer cells].

PubMed

Rybárová, S; Hodorová, I; Vecanová, J; Muri, J; Mihalik, J

2014-01-01

The oncoprotein p53 protein induces cell growth arrest (apoptosis) in response to endo or exogenous stimuli. Mutation of TP53 (gene encoding the p53 protein) is common in human malignancies and alters the conformation of p53. The result is a more stable protein which accumulates in nuclei of tumor cells with loss of function. Mutant p53 is stabilized, and it is possible to detect this form very clearly by immunohistochemistry (IHC). Expression of the MDM2 protein is used as a potential marker of p53 function. P53 levels in normal cells are highly determined by the MDM2 protein (murine double minute 2) - mediated degradation of p53. MDM2 overexpression represents at least one mechanism by which p53 function can be abrogated during tumorigenesis. Lung carcinoma samples were obtained from patients, who underwent radical resection (lobectomy or pulmonectomy and lymphadectomy). Pathological dia-gnosis was based on the WHO criteria. In our study, we investigated the expression of p53 and MDM2 protein that might improve IHC as a marker for p53 status. Proteins were IHC detected in 136 samples of primary lung carcinoma. Immunostaining results of p53 positive samples were compared to IHC expression of MDM2 positive and MDM2 negative samples. Strong brown nuclear staining was visible in p53 and MDM2 positive cells. The most p53 positive cases were samples of squamocellular carcinoma (55%), then samples of large cell carcinoma (53%) and 26% adenocarcinoma samples showed the p53 immunoreactivity. No one sample of different types was p53 positive. When we compared the p53 expression and grade of tumor, we found that the p53 expression increased with the grade of tumor. For statistical evaluation, the chi square test was used. The relationship between p53 expression and type of tumor, also the p53 expression and grade of tumor was statistically significant (p = 0.000425; p = 0.00157). Regarding p53 and MDM2 expression, only nine samples (7%) were simultaneously p53 and MDM2 positive. In 46 (34%) cases, elevation of p53 was combined with MDM2 negative expression. Other tumor samples were either negative for both proteins (71/ 52%), or p53 negative and MDM2 positive in 10 (7%) tumor samples. Absence of p53 staining in most studies indicates absence of p53 mutation, and on the contrary, positive expression of p53 is a sign of p53 mutations with loss of function. In our study, 34% of cases with extensively high level of p53 without increased level of MDM2 were identified. We suppose that these are tumors with inactivating mutations that stabilize p53. On the other hand, tumors with high level of stabilized wildtype p53 protein and simultaneously with increased MDM2 staining (9 samples/7%) represent group with functional p53. In this group of patients, we could expect better prognosis with regard to function of p53 protein.
The Transcription Factor p53 Influences Microglial Activation Phenotype

PubMed Central

Jayadev, Suman; Nesser, Nicole K.; Hopkins, Stephanie; Myers, Scott J.; Case, Amanda; Lee, Rona J.; Seaburg, Luke A.; Uo, Takuma; Murphy, Sean P.; Morrison, Richard S.; Garden, Gwenn A.

2011-01-01

Several neurodegenerative diseases are influenced by the innate immune response in the central nervous system (CNS). Microglia, have pro-inflammatory and subsequently neurotoxic actions as well as anti-inflammatory functions that promote recovery and repair. Very little is known about the transcriptional control of these specific microglial behaviors. We have previously shown that in HIV associated neurocognitive disorders (HAND), the transcription factor p53 accumulates in microglia and that microglial p53 expression is required for the in vitro neurotoxicity of the HIV coat glycoprotein gp120. These findings suggested a novel function for p53 in regulating microglial activation. Here we report that in the absence of p53, microglia demonstrate a blunted response to interferon-γ, failing to increase expression of genes associated with classical macrophage activation or secrete pro-inflammatory cytokines. Microarray analysis of global gene expression profiles revealed increased expression of genes associated with anti-inflammatory functions, phagocytosis and tissue repair in p53 knockout (p53−/−) microglia compared with those cultured from strain matched p53 expressing (p53+/+) mice. We further observed that p53−/− microglia demonstrate increased phagocytic activity in vitro and expression of markers for alternative macrophage activation both in vitro and in vivo. In HAND brain tissue, the alternative activation marker CD163 was expressed in a separate subset of microglia than those demonstrating p53 accumulation. These data suggest that p53 influences microglial behavior, supporting the adoption of a pro-inflammatory phenotype, while p53 deficiency promotes phagocytosis and gene expression associated with alternative activation and anti-inflammatory functions. PMID:21598312
Transcriptional repression of epithelial cell adhesion molecule (EpCAM) contributes to p53 control of breast cancer invasion

PubMed Central

Sankpal, NV; Willman, MW; Fleming, TP; Mayfield, J; Gillanders, WE

2014-01-01

p53 is a tumor suppressor gene with well-characterized roles in cell cycle regulation, apoptosis and the maintenance of genome stability. Recent evidence suggests that p53 may also contribute to the regulation of migration and invasion. Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein that is overexpressed in the majority of human epithelial carcinomas, including breast and colorectal carcinomas. We demonstrate by chromatin immunoprecipitation assays that p53 interacts with a candidate p53 binding site within the EpCAM gene. p53-mediated transcriptional repression of EpCAM was confirmed in gain-of-function, and loss-of-function experimental systems. Induction of wildtype p53 was associated with a significant dose-dependent decrease in EpCAM expression; conversely, specific ablation of p53 was associated with a significant increase in EpCAM expression. At the functional level, specific ablation of p53 expression is associated with increased breast cancer invasion, and this effect is abrogated by concomitant specific ablation of EpCAM expression. Taken together, these biochemical and functional data are the first demonstration that (1) wildtype p53 protein binds to a response element within the EpCAM gene and negatively regulates EpCAM expression, and (2) transcriptional repression of EpCAM contributes to p53 control of breast cancer invasion. PMID:19141643
Andrographolide induces degradation of mutant p53 via activation of Hsp70.

PubMed

Sato, Hirofumi; Hiraki, Masatsugu; Namba, Takushi; Egawa, Noriyuki; Baba, Koichi; Tanaka, Tomokazu; Noshiro, Hirokazu

2018-05-22

The tumor suppressor gene p53 encodes a transcription factor that regulates various cellular functions, including DNA repair, apoptosis and cell cycle progression. Approximately half of all human cancers carry mutations in p53 that lead to loss of tumor suppressor function or gain of functions that promote the cancer phenotype. Thus, targeting mutant p53 as an anticancer therapy has attracted considerable attention. In the current study, a small-molecule screen identified andrographlide (ANDRO) as a mutant p53 suppressor. The effects of ANDRO, a small molecule isolated from the Chinese herb Andrographis paniculata, on tumor cells carrying wild-type or mutant p53 were examined. ANDRO suppressed expression of mutant p53, induced expression of the cyclin-dependent kinase inhibitor p21 and pro-apoptotic proteins genes, and inhibited the growth of cancer cells harboring mutant p53. ANDRO also induced expression of the heat-shock protein (Hsp70) and increased binding between Hsp70 and mutant p53 protein, thus promoting proteasomal degradation of p53. These results provide novel insights into the mechanisms regulating the function of mutant p53 and suggest that activation of Hsp70 may be a new strategy for the treatment of cancers harboring mutant p53.
Friend or Foe: MicroRNAs in the p53 network.

PubMed

Luo, Zhenghua; Cui, Ri; Tili, Esmerina; Croce, Carlo

2018-04-10

The critical tumor suppressor gene TP53 is either lost or mutated in more than half of human cancers. As an important transcriptional regulator, p53 modulates the expression of many microRNAs. While wild-type p53 uses microRNAs to suppress cancer development, microRNAs that are activated by gain-of-function mutant p53 confer oncogenic properties. On the other hand, the expression of p53 is tightly controlled by a fine-tune machinery including microRNAs. MicroRNAs can target the TP53 gene directly or other factors in the p53 network so that expression and function of either the wild-type or the mutant forms of p53 is downregulated. Therefore, depending on the wild-type or mutant p53 context, microRNAs contribute substantially to suppress or exacerbate tumor development. Copyright © 2018. Published by Elsevier B.V.
Small-molecule RETRA suppresses mutant p53-bearing cancer cells through a p73-dependent salvage pathway

PubMed Central

Kravchenko, J. E.; Ilyinskaya, G. V.; Komarov, P. G.; Agapova, L. S.; Kochetkov, D. V.; Strom, E.; Frolova, E. I.; Kovriga, I.; Gudkov, A. V.; Feinstein, E.; Chumakov, P. M.

2008-01-01

Identification of unique features of cancer cells is important for defining specific and efficient therapeutic targets. Mutant p53 is present in nearly half of all cancer cases, forming a promising target for pharmacological reactivation. In addition to being defective for the tumor-suppressor function, mutant p53 contributes to malignancy by blocking a p53 family member p73. Here, we describe a small-molecule RETRA that activates a set of p53-regulated genes and specifically suppresses mutant p53-bearing tumor cells in vitro and in mouse xenografts. Although the effect is strictly limited to the cells expressing mutant p53, it is abrogated by inhibition with RNAi to p73. Treatment of mutant p53-expressing cancer cells with RETRA results in a substantial increase in the expression level of p73, and a release of p73 from the blocking complex with mutant p53, which produces tumor-suppressor effects similar to the functional reactivation of p53. RETRA is active against tumor cells expressing a variety of p53 mutants and does not affect normal cells. The results validate the mutant p53–p73 complex as a promising and highly specific potential target for cancer therapy. PMID:18424558
A novel p53 mutational hotspot in skin tumors from UV-irradiated Xpc mutant mice alters transactivation functions.

PubMed

Inga, Alberto; Nahari, Dorit; Velasco-Miguel, Susana; Friedberg, Errol C; Resnick, Michael A

2002-08-22

A mutation in codon 122 of the mouse p53 gene resulting in a T to L amino acid substitution (T122-->L) is frequently associated with skin cancer in UV-irradiated mice that are both homozygous mutant for the nucleotide excision repair (NER) gene Xpc (Xpc(-/-)) and hemizygous mutant for the p53 gene. We investigated the functional consequences of the mouse T122-->L mutation when expressed either in mammalian cells or in the yeast Saccharomyces cerevisiae. Similar to a non-functional allele, high expression of the T122-->L allele in p53(-/-) mouse embryo fibroblasts and human Saos-2 cells failed to suppress growth. However, the T122-->L mutant p53 showed wild-type transactivation levels with Bax and MDM2 promoters when expressed in either cell type and retained transactivation of the p21 and the c-Fos promoters in one cell line. Using a recently developed rheostatable p53 induction system in yeast we assessed the T122-->L transactivation capacity at low levels of protein expression using 12 different p53 response elements (REs). Compared to wild-type p53 the T122-->L protein manifested an unusual transactivation pattern comprising reduced and enhanced activity with specific REs. The high incidence of the T122-->L mutant allele in the Xpc(-/-) background suggests that both genetic and epigenetic conditions may facilitate the emergence of particular functional p53 mutations. Furthermore, the approach that we have taken also provides for the dissection of functions that may be retained in many p53 tumor alleles.
MiR-142-3p is downregulated in aggressive p53 mutant mouse models of pancreatic ductal adenocarcinoma by hypermethylation of its locus.

PubMed

Godfrey, Jack D; Morton, Jennifer P; Wilczynska, Ania; Sansom, Owen J; Bushell, Martin D

2018-05-29

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive disease with poor prognostic implications. This is partly due to a large proportion of PDACs carrying mutations in TP53, which impart gain-of-function characteristics that promote metastasis. There is evidence that microRNAs (miRNAs) may play a role in both gain-of-function TP53 mutations and metastasis, but this has not been fully explored in PDAC. Here we set out to identify miRNAs which are specifically dysregulated in metastatic PDAC. To achieve this, we utilised established mouse models of PDAC to profile miRNA expression in primary tumours expressing the metastasis-inducing mutant p53 R172H and compared these to two control models carrying mutations, which promote tumour progression but do not induce metastasis. We show that a subset of miRNAs are dysregulated in mouse PDAC tumour tissues expressing mutant p53 R172H , primary cell lines derived from mice with the same mutations and in TP53 null cells with ectopic expression of the orthologous human mutation, p53 R175H . Specifically, miR-142-3p is downregulated in all of these experimental models. We found that DNA methyltransferase 1 (Dnmt1) is upregulated in tumour tissue and cell lines, which express p53 R172H . Inhibition or depletion of Dnmt1 restores miR-142-3p expression. Overexpression of miR-142-3p attenuates the invasive capacity of p53 R172H -expressing tumour cells. MiR-142-3p dysregulation is known to be associated with cancer progression, metastasis and the miRNA is downregulated in patients with PDAC. Here we link TP53 gain-of-function mutations to Dnmt1 expression and in turn miR-142-3p expression. Additionally, we show a correlation between expression of these genes and patient survival, suggesting that they may have potential to be therapeutic targets.
Human Oncoprotein MDM2 Up-regulates Expression of NF-κB2 Precursor p100 Conferring a Survival Advantage to Lung Cells

PubMed Central

Vaughan, Catherine; Mohanraj, Lathika; Singh, Shilpa; Dumur, Catherine I.; Ramamoorthy, Mahesh; Garrett, Carleton T.; Windle, Brad; Yeudall, W. Andrew; Deb, Sumitra

2011-01-01

The current model predicts that MDM2 is primarily overexpressed in cancers with wild-type (WT) p53 and contributes to oncogenesis by degrading p53. Following a correlated expression of MDM2 and NF-κB2 transcripts in human lung tumors, we have identified a novel transactivation function of MDM2. Here, we report that in human lung tumors, overexpression of MDM2 was found in approximately 30% of cases irrespective of their p53 status, and expression of MDM2 and NF-κB2 transcripts showed a highly significant statistical correlation in tumors with WT p53. We investigated the significance of this correlated expression in terms of mechanism and biological function. Increase in MDM2 expression from its own promoter in transgenic mice remarkably enhanced expression of NF-κB2 compared with its non-transgenic littermates. Knockdown or elimination of endogenous MDM2 expression in cultured non-transformed or lung tumor cells drastically reduced expression of NF-κB2 transcripts, suggesting a normal physiological role of MDM2 in regulating NF-κB2 transcription. MDM2 could up-regulate expression of NF-κB2 transcripts when its p53-interaction domain was blocked with Nutlin-3, indicating that the MDM2-p53 interaction is dispensable for up-regulation of NF-κB2 expression. Consistently, analysis of functional domains of MDM2 indicated that although the p53-interaction domain of MDM2 contributes to the up-regulation of the NFκB2 promoter, MDM2 does not require direct interactions with p53 for this function. Accordingly, MDM2 overexpression in non-transformed or lung cancer cells devoid of p53 also generated a significant increase in the expression of NF-κB2 transcript and its targets CXCL-1 and CXCL-10, whereas elimination of MDM2 expression had the opposite effects. MDM2-mediated increase in p100/NF-κB2 expression reduced cell death mediated by paclitaxel. Furthermore, knockdown of NF-κB2 expression retarded cell proliferation. Based on these data, we propose that MDM2-mediated NF-κB2 up-regulation is a combined effect of p53-dependent and independent mechanisms and that it confers a survival advantage to lung cancer cells. PMID:22701761
Rescue of the apoptotic-inducing function of mutant p53 by small molecule RITA.

PubMed

Zhao, Carolyn Y; Grinkevich, Vera V; Nikulenkov, Fedor; Bao, Wenjie; Selivanova, Galina

2010-05-01

Expression of mutant p53 correlates with poor prognosis in many tumors, therefore strategies aimed at reactivation of mutant p53 are likely to provide important benefits for treatment of tumors that are resistant to chemotherapy and radiotherapy. We have previously identified and characterized a small molecule RITA which binds p53 and induces a conformational change which prevents the binding of p53 to several inhibitors, including its own destructor MDM2. In this way, RITA rescues the tumor suppression function of wild type p53. Here, we demonstrate that RITA suppressed the growth and induced apoptosis in human tumor cell lines of a diverse origin carrying mutant p53 proteins. RITA restored transcriptional transactivation and transrepression function of several hot spot p53 mutants. The ability of RITA to rescue the activity of different p53 mutants suggests its generic mechanism of action. Thus, RITA is a promising lead for the development of anti-cancer drugs that reactivate the tumor suppressor function of p53 in cancer cells irrespective whether they express mutant or wild type p53.
Small-molecule MDM2 antagonists reveal aberrant p53 signaling in cancer: Implications for therapy

PubMed Central

Tovar, Christian; Rosinski, James; Filipovic, Zoran; Higgins, Brian; Kolinsky, Kenneth; Hilton, Holly; Zhao, Xiaolan; Vu, Binh T.; Qing, Weiguo; Packman, Kathryn; Myklebost, Ola; Heimbrook, David C.; Vassilev, Lyubomir T.

2006-01-01

The p53 tumor suppressor retains its wild-type conformation and transcriptional activity in half of all human tumors, and its activation may offer a therapeutic benefit. However, p53 function could be compromised by defective signaling in the p53 pathway. Using a small-molecule MDM2 antagonist, nutlin-3, to probe downstream p53 signaling we find that the cell-cycle arrest function of the p53 pathway is preserved in multiple tumor-derived cell lines expressing wild-type p53, but many have a reduced ability to undergo p53-dependent apoptosis. Gene array analysis revealed attenuated expression of multiple apoptosis-related genes. Cancer cells with mdm2 gene amplification were most sensitive to nutlin-3 in vitro and in vivo, suggesting that MDM2 overexpression may be the only abnormality in the p53 pathway of these cells. Nutlin-3 also showed good efficacy against tumors with normal MDM2 expression, suggesting that many of the patients with wild-type p53 tumors may benefit from antagonists of the p53–MDM2 interaction. PMID:16443686
TP53INP1 is a novel p73 target gene that induces cell cycle arrest and cell death by modulating p73 transcriptional activity.

PubMed

Tomasini, Richard; Seux, Mylène; Nowak, Jonathan; Bontemps, Caroline; Carrier, Alice; Dagorn, Jean-Charles; Pébusque, Marie-Josèphe; Iovanna, Juan L; Dusetti, Nelson J

2005-12-08

TP53INP1 is an alternatively spliced gene encoding two nuclear protein isoforms (TP53INP1alpha and TP53INP1beta), whose transcription is activated by p53. When overexpressed, both isoforms induce cell cycle arrest in G1 and enhance p53-mediated apoptosis. TP53INP1s also interact with the p53 gene and regulate p53 transcriptional activity. We report here that TP53INP1 expression is induced during experimental acute pancreatitis in p53-/- mice and in cisplatin-treated p53-/- mouse embryo fibroblasts (MEFs). We demonstrate that ectopic expression of p73, a p53 homologue, leads to TP53INP1 induction in p53-deficient cells. In turn, TP53INP1s alters the transactivation capacity of p73 on several p53-target genes, including TP53INP1 itself, demonstrating a functional association between p73 and TP53INP1s. Also, when overexpressed in p53-deficient cells, TP53INP1s inhibit cell growth and promote cell death as assessed by cell cycle analysis and colony formation assays. Finally, we show that TP53INP1s potentiate the capacity of p73 to inhibit cell growth, that effect being prevented when the p53 mutant R175H is expressed or when p73 expression is blocked by a siRNA. These results suggest that TP53INP1s are functionally associated with p73 to regulate cell cycle progression and apoptosis, independently from p53.
The roles of p53R2 in cancer progression based on the new function of mutant p53 and cytoplasmic p21.

PubMed

Yousefi, Bahman; Rahmati, Mohammad; Ahmadi, Yasin

2014-03-18

Although the deregulated expression of p53R2, a p53-inducible protein and homologue of the R2 subunit of ribonucleotide reductase, has been detected in several human cancers, p53R2 roles in cancer progression and malignancy still remains controversial. In this article, we present a viable hypothesis about the roles of p53R2 in cancer progression and therapy resistance based on the roles of cytoplasmic p21 and mutant p53. Since p53R2 can up-regulate p21 and p21, it in turn has a dual role in cell cycle. Hence, p53R2 can play a dual role in cell cycle progression. In addition, because p53 is the main regulator of p53R2, the mutant p53 may induce the expression of p53R2 in some cancer cells based on the "keep of function" phenomenon. Therefore, depending on the locations of p21 and the new abilities of mutant p53, p53R2 has dual role in cell cycle progression. Since the DNA damaging therapies induce p53R2 expression through the induction of p53, p53R2 can be the main therapy resistance mediator in cancers with cytoplasmic p21. Copyright © 2014 Elsevier Inc. All rights reserved.
Mutant p53-R273H mediates cancer cell survival and anoikis resistance through AKT-dependent suppression of BCL2-modifying factor (BMF).

PubMed

Tan, B S; Tiong, K H; Choo, H L; Chung, F Fei-Lei; Hii, L-W; Tan, S H; Yap, I K S; Pani, S; Khor, N T W; Wong, S F; Rosli, R; Cheong, S-K; Leong, C-O

2015-07-16

p53 is the most frequently mutated tumor-suppressor gene in human cancers. Unlike other tumor-suppressor genes, p53 mutations mainly occur as missense mutations within the DNA-binding domain, leading to the expression of full-length mutant p53 protein. Mutant p53 proteins not only lose their tumor-suppressor function, but may also gain new oncogenic functions and promote tumorigenesis. Here, we showed that silencing of endogenous p53-R273H contact mutant, but not p53-R175H conformational mutant, reduced AKT phosphorylation, induced BCL2-modifying factor (BMF) expression, sensitized BIM dissociation from BCL-XL and induced mitochondria-dependent apoptosis in cancer cells. Importantly, cancer cells harboring endogenous p53-R273H mutant were also found to be inherently resistant to anoikis and lack BMF induction following culture in suspension. Underlying these activities is the ability of p53-R273H mutant to suppress BMF expression that is dependent on constitutively active PI3K/AKT signaling. Collectively, these findings suggest that p53-R273H can specifically drive AKT signaling and suppress BMF expression, resulting in enhanced cell survivability and anoikis resistance. These findings open the possibility that blocking of PI3K/AKT will have therapeutic benefit in mutant p53-R273H expressing cancers.
A protein folding molecular imaging biosensor monitors the effects of drugs that restore mutant p53 structure and its downstream function in glioblastoma cells

PubMed Central

Paulmurugan, Ramasamy; Afjei, Rayhaneh; Sekar, Thillai V.; Babikir, Husam A.; Massoud, Tarik F.

2018-01-01

Misfolding mutations in the DNA-binding domain of p53 alter its conformation, affecting the efficiency with which it binds to chromatin to regulate target gene expression and cell cycle checkpoint functions in many cancers, including glioblastoma. Small molecule drugs that recover misfolded p53 structure and function may improve chemotherapy by activating p53-mediated senescence. We constructed and optimized a split Renilla luciferase (RLUC) complementation molecular biosensor (NRLUC-p53-CRLUC) to determine small molecule-meditated folding changes in p53 protein. After initial evaluation of the biosensor in three different cells lines, we engineered endogenously p53P98L mutant (i.e. not affecting the DNA-binding domain) Ln229 glioblastoma cells, to express the biosensor containing one of four different p53 proteins: p53wt, p53Y220C, p53G245S and p53R282W. We evaluated the consequent phenotypic changes in these four variant cells as well as the parental cells after exposure to PhiKan083 and SCH529074, drugs previously reported to activate mutant p53 folding. Specifically, we measured induced RLUC complementation and consequent therapeutic response. Upon stable transduction with the p53 biosensors, we demonstrated that these originally p53P98L Ln229 cells had acquired p53 cellular phenotypes representative of each p53 protein expressed within the biosensor fusion protein. In these engineered variants we found a differential drug response when treated with doxorubicin and temozolomide, either independently or in combination with PhiKan083 or SCH529074. We thus developed a molecular imaging complementation biosensor that mimics endogenous p53 function for use in future applications to screen novel or repurposed drugs that counter the effects of misfolding mutations responsible for oncogenic structural changes in p53. PMID:29765555
The absence of p53 during Human Cytomegalovirus infection leads to decreased UL53 expression, disrupting UL50 localization to the inner nuclear membrane, and thereby inhibiting capsid nuclear egress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuan, Man I; O’Dowd, John M.; Fortunato, Elizabeth

Our electron microscopy study (Kuan et al., 2016) found HCMV nuclear capsid egress was significantly reduced in p53 knockout cells (p53KOs), correlating with inhibited formation of infoldings of the inner nuclear membrane (IINMs). Molecular examination of these phenomena has found p53KOs expressed UL97 and phosphorylated lamins, however the lamina failed to remodel. The nuclear egress complex (NEC) protein UL50 was expressed in almost all cells. UL50 re-localized to the inner nuclear membrane (INM) in ~90% of wt cells, but only ~35% of p53KOs. UL53 expression was significantly reduced in p53KOs, and cells lacking UL50 nuclear staining, expressed no UL53. Re-introductionmore » of p53 into p53KOs largely recovered UL53 positivity and UL50 nuclear re-localization. Nuclear rim located UL50/53 puncta, which co-localized with the major capsid protein, were largely absent in p53KOs. We believe these puncta were IINMs. In the absence of p53, UL53 expression was inhibited, disrupting formation of the NEC/IINMs, and reducing functional virion secretion. -- Highlights: •Phosphorylated nuclear lamins were inefficiently remodeled in p53KO cells. •p53KO cells expressed UL50, but it was not efficiently targeted to the nuclear rim. •UL53 was not expressed in the large majority of p53KO cells. •Cells failing to express UL53 did not localize UL50 to the nucleus. •NEC puncta/infoldings of the inner nuclear membrane were scarce in p53KO cells.« less
Suppression of p53-inducible gene 3 is significant for glioblastoma progression and predicts poor patient prognosis.

PubMed

Quan, Jishu; Li, Yong; Jin, Meihua; Chen, Dunfu; Yin, Xuezhe; Jin, Ming

2017-03-01

Glioblastoma is the most malignant and invasive brain tumor with extremely poor prognosis. p53-inducible gene 3, a downstream molecule of the tumor suppressor p53, has been found involved in apoptosis and oxidative stress response. However, the functions of p53-inducible gene 3(PIG3) in cancer are far from clear including glioblastoma. In this study, we found that p53-inducible gene 3 expression was suppressed in glioblastoma tissues compared with normal tissues. And the expression of p53-inducible gene 3 was significantly associated with the World Health Organization grade. Patients with high p53-inducible gene 3 expression have a significantly longer median survival time (15 months) than those with low p53-inducible gene 3 expression (8 months). According to Cox regression analysis, p53-inducible gene 3 was an independent prognostic factor with multivariate hazard ratio of 0.578 (95% confidence interval, 0.352-0.947; p = 0.030) for overall survival. Additionally, gain and loss of function experiments showed that knockdown of p53-inducible gene 3 significantly increased the proliferation and invasion ability of glioblastoma cells while overexpression of p53-inducible gene 3 inhibited the proliferation and invasion ability. The results of in vivo glioblastoma models further confirmed that p53-inducible gene 3 suppression promoted glioblastoma progression. Altogether, our data suggest that high expression of p53-inducible gene 3 is significant for glioblastoma inhibition and p53-inducible gene 3 independently indicates good prognosis in patients, which might be a novel prognostic biomarker or potential therapeutic target in glioblastoma.
AAVPG: A vigilant vector where transgene expression is induced by p53

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bajgelman, Marcio C.; Medrano, Ruan F.V.; Carvalho, Anna Carolina P.V.

2013-12-15

Using p53 to drive transgene expression from viral vectors may provide on demand expression in response to physiologic stress, such as hypoxia or DNA damage. Here we introduce AAVPG, an adeno-associated viral (AAV) vector where a p53-responsive promoter, termed PG, is used to control transgene expression. In vitro assays show that expression from the AAVPG-luc vector was induced specifically in the presence of functional p53 (1038±202 fold increase, p<0.001). The AAVPG-luc vector was an effective biosensor of p53 activation in response to hypoxia (4.48±0.6 fold increase in the presence of 250 µM CoCl{sub 2}, p<0.001) and biomechanical stress (2.53±0.4 foldmore » increase with stretching, p<0.05). In vivo, the vigilant nature of the AAVPG-luc vector was revealed after treatment of tumor-bearing mice with doxorubicin (pre-treatment, 3.4×10{sup 5}±0.43×10{sup 5} photons/s; post-treatment, 6.6×10{sup 5}±2.1×10{sup 5} photons/s, p<0.05). These results indicate that the AAVPG vector is an interesting option for detecting p53 activity both in vitro and in vivo. - Highlights: • AAV vector where transgene expression is controlled by the tumor suppressor p53. • The new vector, AAVPG, shown to function as a biosensor of p53 activity, in vitro and in vivo. • The p53 activity monitored by the AAVPG vector is relevant to cancer and other diseases. • AAVPG reporter gene expression was activated upon DNA damage, hypoxia and mechanical stress.« less
Bcl-2/Bax protein ratio predicts 5-fluorouracil sensitivity independently of p53 status

PubMed Central

Mirjolet, J-F; Barberi-Heyob, M; Didelot, C; Peyrat, J-P; Abecassis, J; Millon, R; Merlin, J-L

2000-01-01

p53 tumour-suppressor gene is involved in cell growth control, arrest and apoptosis. Nevertheless cell cycle arrest and apoptosis induction can be observed in p53-defective cells after exposure to DNA-damaging agents such as 5-fluorouracil (5-FU) suggesting the importance of alternative pathways via p53-independent mechanisms. In order to establish relationship between p53 status, cell cycle arrest, Bcl-2/Bax regulation and 5-FU sensitivity, we examined p53 mRNA and protein expression and p53 protein functionality in wild-type (wt) and mutant (mt) p53 cell lines. p53 mRNA and p53 protein expression were determined before and after exposure to equitoxic 5-FU concentration in six human carcinoma cell lines differing in p53 status and displaying marked differences in 5-FU sensitivity, with IC 50 values ranging from 0.2–22.6 mM. 5-FU induced a rise in p53 mRNA expression in mt p53 cell lines and in human papilloma virus positive wt p53 cell line, whereas significant decrease in p53 mRNA expression was found in wt p53 cell line. Whatever p53 status, 5-FU altered p53 transcriptional and translational regulation leading to up-regulation of p53 protein. In relation with p53 functionality, but independently of p53 mutational status, after exposure to 5-FU equitoxic concentration, all cell lines were able to arrest in G1. No relationship was evidenced between G1 accumulation ability and 5-FU sensitivity. Moreover, after 5-FU exposure, Bax and Bcl-2 proteins regulation was under p53 protein control and a statistically significant relationship (r= 0.880,P= 0.0097) was observed between Bcl-2/Bax ratio and 5-FU sensitivity. In conclusion, whatever p53 status, Bcl-2 or Bax induction and Bcl-2/Bax protein ratio were correlated to 5-FU sensitivity. © 2000 Cancer Research Campaign PMID:11044365

LincRNA-p21 activates p21 in cis to promote Polycomb target gene expression and to enforce the G1/S checkpoint

PubMed Central

Dimitrova, Nadya; Zamudio, Jesse R.; Jong, Robyn M.; Soukup, Dylan; Resnick, Rebecca; Sarma, Kavitha; Ward, Amanda J.; Raj, Arjun; Lee, Jeannie; Sharp, Phillip A.; Jacks, Tyler

2014-01-01

SUMMARY The p53-regulated long non-coding RNA lincRNA-p21 has been proposed to act in trans via several mechanisms ranging from repressing genes in the p53 transcriptional network to regulating mRNA translation and protein stability. To further examine lincRNA-p21 function we generated a conditional knockout mouse model. We find that lincRNA-p21 predominantly functions in cis to activate expression of its neighboring gene, p21. Mechanistically, we show that lincRNA-p21 acts in concert with hnRNP-K as a co-activator for p53-dependent p21 transcription. Additional phenotypes of lincRNA-p21 deficiency could be attributed to diminished p21 levels, including deregulated expression and altered chromatin state of some Polycomb target genes, defective G1/S checkpoint, increased proliferation rates, and enhanced reprogramming efficiency. These findings indicate that lincRNA-p21 affects global gene expression and influences the p53 tumor suppressor pathway by acting in cis as a locus-restricted co-activator for p53-mediated p21 expression. PMID:24857549
Comparison of the QuantiGene 2.0 Assay and Real-Time RT-PCR in the Detection of p53 Isoform mRNA Expression in Formalin-Fixed Paraffin-Embedded Tissues- A Preliminary Study

PubMed Central

Morten, Brianna C.; Scott, Rodney J.; Avery-Kiejda, Kelly A.

2016-01-01

p53 is expressed as multiple smaller isoforms whose functions in cancer are not well understood. The p53 isoforms demonstrate abnormal expression in different cancers, suggesting they are important in modulating the function of full-length p53 (FLp53). The quantification of relative mRNA expression has routinely been performed using real-time PCR (qPCR). However, there are serious limitations when detecting p53 isoforms using this method, particularly for formalin-fixed paraffin-embedded (FFPE) tissues. The use of FFPE tumours would be advantageous to correlate expression of p53 isoforms with important clinical features of cancer. One alternative method of RNA detection is the hybridization-based QuantiGene 2.0 Assay, which has been shown to be advantageous for the detection of RNA from FFPE tissues. In this pilot study, we compared the QuantiGene 2.0 Assay to qPCR for the detection of FLp53 and its isoform Δ40p53 in matched fresh frozen (FF) and FFPE breast tumours. FLp53 mRNA expression was detected using qPCR in FF and FFPE tissues, but Δ40p53 mRNA was only detectable in FF tissues. Similar results were obtained for the QuantiGene 2.0 Assay. FLp53 relative mRNA expression was shown to be strongly correlated between the two methods (R2 = 0.9927, p = 0.0031) in FF tissues, however Δ40p53 was not (R2 = 0.4429, p = 0.3345). When comparing the different methods for the detection of FLp53 mRNA from FFPE and FF samples, no correlation (R2 = 0.0002, p = 0.9863) was shown using the QuantiGene 2.0 Assay, and in contrast, the level of expression was highly correlated between the two tissues using qPCR (R2 = 0.8753, p = 0.0644). These results suggest that both the QuantiGene 2.0 Assay and qPCR methods are inadequate for the quantification of Δ40p53 mRNA in FFPE tissues. Therefore, alternative methods of RNA detection and quantification are required to study the relative expression of Δ40p53 in FFPE samples. PMID:27832134
Expression of C-terminal deleted p53 isoforms in neuroblastoma

PubMed Central

Goldschneider, David; Horvilleur, Emilie; Plassa, Louis-François; Guillaud-Bataille, Marine; Million, Karine; Wittmer-Dupret, Evelyne; Danglot, Gisèle; de Thé, Hughes; Bénard, Jean; May, Evelyne; Douc-Rasy, Sétha

2006-01-01

The tumor suppressor gene, p53, is rarely mutated in neuroblastomas (NB) at the time of diagnosis, but its dysfunction could result from a nonfunctional conformation or cytoplasmic sequestration of the wild-type p53 protein. However, p53 mutation, when it occurs, is found in NB tumors with drug resistance acquired over the course of chemotherapy. As yet, no study has been devoted to the function of the specific p53 mutants identified in NB cells. This study includes characterization and functional analysis of p53 expressed in eight cell lines: three wild-type cell lines and five cell lines harboring mutations. We identified two transcription-inactive p53 variants truncated in the C-terminus, one of which corresponded to the p53β isoform recently identified in normal tissue by Bourdon et al. [J. C. Bourdon, K. Fernandes, F. Murray-Zmijewski, G. Liu, A. Diot, D. P. Xirodimas, M. K. Saville and D. P. Lane (2005) Genes Dev., 19, 2122–2137]. Our results show, for the first time, that the p53β isoform is the only p53 species to be endogenously expressed in the human NB cell line SK-N-AS, suggesting that the C-terminus truncated p53 isoforms may play an important role in NB tumor development. PMID:17028100
Radiation-Induced Salivary Gland Dysfunction Results From p53-Dependent Apoptosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avila, Jennifer L.; Grundmann, Oliver; Burd, Randy

2009-02-01

Purpose: Radiotherapy for head-and-neck cancer causes adverse secondary side effects in the salivary glands and results in diminished quality of life for the patient. A previous in vivo study in parotid salivary glands demonstrated that targeted head-and-neck irradiation resulted in marked increases in phosphorylated p53 (serine{sup 18}) and apoptosis, which was suppressed in transgenic mice expressing a constitutively active mutant of Akt1 (myr-Akt1). Methods and Materials: Transgenic and knockout mouse models were exposed to irradiation, and p53-mediated transcription, apoptosis, and salivary gland dysfunction were analyzed. Results: The proapoptotic p53 target genes PUMA and Bax were induced in parotid salivary glandsmore » of mice at early time points after therapeutic radiation. This dose-dependent induction requires expression of p53 because no radiation-induced expression of PUMA and Bax was observed in p53-/- mice. Radiation also induced apoptosis in the parotid gland in a dose-dependent manner, which was p53 dependent. Furthermore, expression of p53 was required for the acute and chronic loss of salivary function after irradiation. In contrast, apoptosis was not induced in p53-/- mice, and their salivary function was preserved after radiation exposure. Conclusions: Apoptosis in the salivary glands after therapeutic head-and-neck irradiation is mediated by p53 and corresponds to salivary gland dysfunction in vivo.« less
p53 functional impairment and high p21waf1/cip1 expression in human T-cell lymphotropic/leukemia virus type I-transformed T cells.

PubMed

Cereseto, A; Diella, F; Mulloy, J C; Cara, A; Michieli, P; Grassmann, R; Franchini, G; Klotman, M E

1996-09-01

Human T-cell lymphotropic/leukemia virus type I (HTLV-I) is associated with T-cell transformation both in vivo and in vitro. Although some of the mechanisms responsible for transformation remain unknown, increasing evidence supports a direct role of viral as well as dysregulated cellular proteins in transformation. We investigated the potential role of the tumor suppressor gene p53 and of the p53-regulated gene, p21waf1/cip1 (wild-type p53 activated fragment 1/cycling dependent kinases [cdks] interacting protein 1), in HTLV-I-infected T cells. We have found that the majority of HTLV-I-infected T cells have the wild-type p53 gene. However, its function in HTLV-I-transformed cells appears to be impaired, as shown by the lack of appropriate p53-mediated responses to ionizing radiation (IR). Interestingly, the expression of the p53 inducible gene, p21waf1/cip1, is elevated at the messenger ribonucleic acid and protein levels in all HTLV-I-infected T-cell lines examined as well as in Taxl-1, a human T-cell line stably expressing Tax. Additionally, Tax induces upregulation of a p21waf1/cip1 promoter-driven luciferase gene in p53 null cells, and increases p21waf1/cip1 expression in Jurkat T cells. These findings suggest that the Tax protein is at least partially responsible for the p53-independent expression of p21waf1/cip1 in HTLV-I-infected cells. Dysregulation of p53 and p21waf1/cip1 proteins regulating cell-cycle progression, may represent an important step in HTLV-I-induced T-cell transformation.
p53-dependent cell death/apoptosis is required for a productive adenovirus infection.

PubMed

Hall, A R; Dix, B R; O'Carroll, S J; Braithwaite, A W

1998-09-01

The p53 tumor suppressor protein binds to both cellular and viral proteins, which influence its biological activity. One such protein is the large E1b tumor antigen (E1b58kDa) from adenoviruses (Ads), which abrogates the ability of p53 to transactivate various promoters. This inactivation of p53 function is believed to be the mechanism by which E1b58kDa contributes to the cell transformation process. Although the p53-E1b58kDa complex occurs during infection and is conserved among different serotypes, there are limited data demonstrating that it has a role in virus replication. However, loss of p53 expression occurs after adenovirus infection of human cells and an E1b58kDa deletion mutant (Onyx-015, also called dl 1520) selectively replicates in p53-defective cells. These (and other) data indicate a plausible hypothesis is that loss of p53 function may be conducive to efficient adenovirus replication. However, wild-type (wt) Ad5 grows more efficiently in cells expressing a wt p53 protein. These studies indicate that the hypothesis may be an oversimplification. Here, we show that cells expressing wt p53, as well as p53-defective cells, allow adenovirus replication, but only cells expressing wt p53 show evidence of virus-induced cytopathic effect. This correlates with the ability of adenovirus to induce cell death. Our data indicate that p53 plays a necessary part in mediating cellular destruction to allow a productive adenovirus infection. In contrast, p53-deficient cells are less sensitive to the cytolytic effects of adenovirus and as such raise questions about the use of E1b58kDa-deficient adenoviruses in tumor therapy.
Novel function of STAT1beta in B cells: induction of cell death by a mechanism different from that of STAT1alpha.

PubMed

Najjar, Imen; Schischmanoff, Pierre Olivier; Baran-Marszak, Fanny; Deglesne, Pierre-Antoine; Youlyouz-Marfak, Ibtissam; Pampin, Mathieu; Feuillard, Jean; Bornkamm, Georg W; Chelbi-Alix, Mounira K; Fagard, Remi

2008-12-01

Alternate splicing of STAT1 produces two isoforms: alpha, known as the active form, and beta, previously shown to act as a dominant-negative factor. Most studies have dealt with STAT1alpha, showing its involvement in cell growth control and cell death. To examine the specific function of either isoform in cell death, a naturally STAT1-deficient human B cell line was transfected to express STAT1alpha or STAT1beta. STAT1alpha, expressed alone, enhanced cell death, potentiated the fludarabine-induced apoptosis, and enhanced the nuclear location, the phosphorylation, and the transcriptional activity of p53. Unexpectedly, STAT1beta, expressed alone, induced cell death through a mechanism that was independent of the nuclear function of p53. Indeed, in STAT1beta-expressing B cells, p53 was strictly cytoplasmic where it formed clusters, and there was no induction of the transcriptional activity of p53. These data reveal a novel role of STAT1beta in programmed cell death, which is independent of p53.
p73 Protein Expression Correlates With Radiation-Induced Apoptosis in the Lack of p53 Response to Radiation Therapy for Cervical Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wakatsuki, Masaru; Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba; Ohno, Tatsuya

2008-03-15

Purpose: p73 belongs to the p53 tumor suppressor family of genes and can inhibit cell growth in a p53-like manner by inducing apoptosis or cell cycle arrest. Here, we investigated whether p73 could compensate for impaired p53 function in apoptosis induced by radiation therapy (RT) for cervical cancer. Methods and Materials: Sixty-eight patients with squamous cell carcinoma of the cervix who received definitive RT combined with (n = 37) or without (n = 31) cisplatin were investigated. Biopsy specimens were excised from the cervical tumor before RT and after 9 Gy. Results: Mean apoptosis index (AI) was 0.93% before RTmore » and 1.97% after 9 Gy with a significant increase (p < 0.001). For all patients, there was a significant correlation between p73 expression positivity after 9 Gy and AI ratio (AI after 9 Gy/AI before RT) (p = 0.021). Forty-one patients were regarded as the p53-responding group according to the expression of p53 after 9 Gy, whereas the remaining 27 patients were regarded as the p53-nonresponding group. A significant correlation between p73 expression after 9 Gy and AI ratio was observed in the p53-non-responding group (p < 0.001) but not in the p53-responding group (p = 0.940). Conclusion: Our results suggest that p73 plays an important role in compensating for the lack of p53 function in radiation-induced apoptosis of cervical cancer.« less
PRL-3 promotes breast cancer progression by downregulating p14ARF-mediated p53 expression.

PubMed

Xie, Hua; Wang, Hao

2018-03-01

Prior studies have demonstrated that phosphatase of regenerating liver-3 (PRL-3) serves avital function in cell proliferation and metastasis in breast cancer. However, the molecular mechanisms underlying the function of PRL-3 in breast cancer remain unknown. PRL-3 expression was analyzed in 24 pairs of breast cancer and normal tissues using the reverse transcription-quantitative polymerase chain reaction assay. The results of the present study identified that the expression of PLR-3 in breast cancer tissues was increased 4.2-fold, compared with normal tissues. Notably, overexpression of PRL-3 significantly promoted the proliferation of cancer cells and inhibited endogenous p53 expression by downregulating the expression level of p14 alternate reading frame (p14 ARF ). In addition, decreased expression levels of PRL-3 resulted in decreased breast cancer cell proliferation and increased expression level of p14 ARF . These results suggested that PRL-3 enhances cell proliferation by downregulating p14 ARF expression, which results in decreased levels ofp53. The results of the present study demonstrated that PRL-3 promotes tumor proliferation by affecting the p14 ARF -p53 axis, and that it may serve as a prognostic marker for patients with breast cancer.
The antagonism between MCT-1 and p53 affects the tumorigenic outcomes

PubMed Central

2010-01-01

Background MCT-1 oncoprotein accelerates p53 protein degradation via a proteosome pathway. Synergistic promotion of the xenograft tumorigenicity has been demonstrated in circumstance of p53 loss alongside MCT-1 overexpression. However, the molecular regulation between MCT-1 and p53 in tumor development remains ambiguous. We speculate that MCT-1 may counteract p53 through the diverse mechanisms that determine the tumorigenic outcomes. Results MCT-1 has now identified as a novel target gene of p53 transcriptional regulation. MCT-1 promoter region contains the response elements reactive with wild-type p53 but not mutant p53. Functional p53 suppresses MCT-1 promoter activity and MCT-1 mRNA stability. In a negative feedback regulation, constitutively expressed MCT-1 decreases p53 promoter function and p53 mRNA stability. The apoptotic events are also significantly prevented by oncogenic MCT-1 in a p53-dependent or a p53-independent fashion, according to the genotoxic mechanism. Moreover, oncogenic MCT-1 promotes the tumorigenicity in mice xenografts of p53-null and p53-positive lung cancer cells. In support of the tumor growth are irrepressible by p53 reactivation in vivo, the inhibitors of p53 (MDM2, Pirh2, and Cop1) are constantly stimulated by MCT-1 oncoprotein. Conclusions The oppositions between MCT-1 and p53 are firstly confirmed at multistage processes that include transcription control, mRNA metabolism, and protein expression. MCT-1 oncogenicity can overcome p53 function that persistently advances the tumor development. PMID:21138557
Alterations of mitochondrial biogenesis in chronic lymphocytic leukemia cells with loss of p53

PubMed Central

Ogasawara, Marcia A.; Liu, Jinyun; Pelicano, Helene; Hammoudi, Naima; Croce, Carlo M.; Keating, Michael J.; Huang, Peng

2016-01-01

Deletion of chromosome 17p with a loss of p53 is an unfavorable cytogenetic change in chronic lymphocytic leukemia (CLL) with poor clinical outcome. Since p53 affects mitochondrial function and integrity, we examined possible mitochondrial changes in CLL mice with TCL1-Tg/p53−/− and TCL1-Tg/p53+/+ genotypes and in primary leukemia cells from CLL patients with or without 17p-deletion. Although the expression of mitochondrial COX1, ND2, and ND6 decreased in p53−/−CLL cells, there was an increase in mitochondrial biogenesis as evidenced by higher mitochondrial mass and mtDNA copy number associated with an elevated expression of TFAM and PGC-1α. Surprisingly, the overall mitochondrial respiratory activity and maximum reserved capacity increased in p53−/− CLL cells. Our study suggests that leukemia cells lacking p53 seem able to maintain respiratory function by compensatory increase in mitochondrial biogenesis. PMID:27650502
Synergistic effect of p53 on TSA-induced stanniocalcin 1 expression in human nasopharyngeal carcinoma cells, CNE2.

PubMed

Ching, L Y; Yeung, Bonnie H Y; Wong, Chris K C

2012-06-01

Human stanniocalcin 1 (STC1) has recently been identified as a putative protein factor involved in cellular apoptosis. The use of histone deacetylase inhibitor (i.e. trichostatin A (TSA)) and doxorubicin (Dox) is one of the common treatment methods to induce apoptosis in human cancer cells. A study on TSA and Dox-mediated apoptosis may shed light on the regulation and function of STC1 in cancer treatment. In this study, TSA and Dox cotreatment in human nasopharyngeal carcinoma cells (CNE2) elicited synergistic effects on STC1 gene expression and cellular apoptosis. An activation of p53 (TP53) transcriptional activity in Dox- or Dox+TSA-treated cells was revealed by the increased expression levels of p53 mRNA/protein as well as p53-driven luciferase activities. To elucidate the possible involvement of p53 in STC1 gene transcription, a vector expressing wild-type or dominant negative (DN) p53 was transiently transfected into the cells. Both STC1 promoter luciferase constructs and chromatin immunoprecipitation assays did not support the direct role of p53 in STC1 gene transactivation. However, the synergistic effects of p53 on the induction of NF-κB phosphorylation and the recruitment of acetylated histone H3 in STC1 promoter were observed in TSA-cotreated cells. The overexpression of exogenous STC1 sensitized apoptosis in Dox-treated cells. Taken together, this study provides data to show the cross talk of NF-κB, p53, and histone protein in the regulation of STC1 expression and function.
A combination of p53-activating APR-246 and phosphatidylserine-targeting antibody potently inhibits tumor development in hormone-dependent mutant p53-expressing breast cancer xenografts

PubMed Central

Liang, Yayun; Mafuvadze, Benford; Besch-Williford, Cynthia; Hyder, Salman M

2018-01-01

Background Between 30 and 40% of human breast cancers express a defective tumor suppressor p53 gene. Wild-type p53 tumor suppressor protein promotes cell-cycle arrest and apoptosis and inhibits vascular endothelial growth factor–dependent angiogenesis, whereas mutant p53 protein (mtp53) lacks these functions, resulting in tumor cell survival and metastasis. Restoration of p53 function is therefore a promising drug-targeted strategy for combating mtp53-expressing breast cancer. Methods In this study, we sought to determine whether administration of APR-246, a small-molecule drug that restores p53 function, in combination with 2aG4, an antibody that targets phosphatidylserine residues on tumor blood vessels and disrupts tumor vasculature, effectively inhibits advanced hormone-dependent breast cancer tumor growth. Results APR-246 reduced cell viability in mtp53-expressing BT-474 and T47-D human breast cancer cells in vitro, and significantly induced apoptosis in a dose-dependent manner. However, APR-246 did not reduce cell viability in MCF-7 breast cancer cells, which express wild-type p53. We next examined APR-246’s anti-tumor effects in vivo using BT-474 and T47-D tumor xenografts established in female nude mice. Tumor-bearing mice were treated with APR-246 and/or 2aG4 and tumor volume followed over time. Tumor growth was more effectively suppressed by combination treatment than by either agent alone, and combination therapy completely eradicated some tumors. Immunohistochemistry analysis of tumor tissue sections demonstrated that combination therapy more effectively induced apoptosis and reduced cell proliferation in tumor xenografts than either agent alone. Importantly, combination therapy dramatically reduced the density of blood vessels, which serve as the major route for tumor metastasis, in tumor xenografts compared with either agent alone. Conclusion Based on our findings, we contend that breast tumor growth might effectively be controlled by simultaneous targeting of mtp53 protein and tumor blood vessels in mtp53-expressing cancers. PMID:29606888
Human papilloma virus type16 E6 deregulates CHK1 and sensitizes human fibroblasts to environmental carcinogens independently of its effect on p53

PubMed Central

Chen, Bo; Simpson, Dennis A.; Zhou, Yingchun; Mitra, Amritava; Mitchell, David L.; Cordeiro-Stone, Marila; Kaufmann, William K.

2015-01-01

After treatment with ultraviolet radiation (UV), human fibroblasts that express the HPV type 16 E6 oncoprotein display defects in repair of cyclobutane pyrimidine dimers, hypersensitivity to inactivation of clonogenic survival and an inability to sustain DNA replication. To determine whether these effects are specific to depletion of p53 or inactivation of its function, fibroblast lines were constructed with ectopic expression of a dominant-negative p53 allele (p53-H179Q) to inactivate function or a short-hairpin RNA (p53-RNAi) to deplete expression of p53. Only the expression of HPV16E6 sensitized fibroblasts to UV or the chemical carcinogen, benzo[a]pyrene diolepoxide I (BPDE). Carcinogen-treated cells expressing p53-H179Q or p53-RNAi were resistant to inactivation of colony formation and did not suffer replication arrest. CHK1 is a key checkpoint kinase in the response to carcinogen-induced DNA damage. Control and p53-RNAi-expressing fibroblasts displayed phosphorylation of Ser345 on CHK1 45–120 min after carcinogen treatment with a return to near baseline phosphorylation by 6 h after treatment. HPV16E6-expressing fibroblasts displayed enhanced and sustained phosphorylation of CHK1. This was associated with enhanced phosphorylation of Thr68 on CHK2 and Ser139 on H2AX, both markers of severe replication stress and DNA double strand breaks. Incubation with the phosphatase inhibitor okadaic acid produced more phosphorylation of CHK1 in UV-treated HPV16E6-expressing cells than in p53-H179Q-expressing cells suggesting that HPV16E6 may interfere with the recovery of coupled DNA replication at replication forks that are stalled at [6-4]pyrimidine-pyrimidone photoproducts and BPDE-DNA adducts. The results indicate that HPV16E6 targets a protein or proteins other than p53 to deregulate the activity of CHK1 in carcinogen-damaged cells. PMID:19411857
Activation of endogenous p53 by combined p19Arf gene transfer and nutlin-3 drug treatment modalities in the murine cell lines B16 and C6

PubMed Central

2010-01-01

Background Reactivation of p53 by either gene transfer or pharmacologic approaches may compensate for loss of p19Arf or excess mdm2 expression, common events in melanoma and glioma. In our previous work, we constructed the pCLPG retroviral vector where transgene expression is controlled by p53 through a p53-responsive promoter. The use of this vector to introduce p19Arf into tumor cells that harbor p53wt should yield viral expression of p19Arf which, in turn, would activate the endogenous p53 and result in enhanced vector expression and tumor suppression. Since nutlin-3 can activate p53 by blocking its interaction with mdm2, we explored the possibility that the combination of p19Arf gene transfer and nutlin-3 drug treatment may provide an additive benefit in stimulating p53 function. Methods B16 (mouse melanoma) and C6 (rat glioma) cell lines, which harbor p53wt, were transduced with pCLPGp19 and these were additionally treated with nutlin-3 or the DNA damaging agent, doxorubicin. Viral expression was confirmed by Western, Northern and immunofluorescence assays. p53 function was assessed by reporter gene activity provided by a p53-responsive construct. Alterations in proliferation and viability were measured by colony formation, growth curve, cell cycle and MTT assays. In an animal model, B16 cells were treated with the pCLPGp19 virus and/or drugs before subcutaneous injection in C57BL/6 mice, observation of tumor progression and histopathologic analyses. Results Here we show that the functional activation of endogenous p53wt in B16 was particularly challenging, but accomplished when combined gene transfer and drug treatments were applied, resulting in increased transactivation by p53, marked cell cycle alteration and reduced viability in culture. In an animal model, B16 cells treated with both p19Arf and nutlin-3 yielded increased necrosis and decreased BrdU marking. In comparison, C6 cells were quite susceptible to either treatment, yet p53 was further activated by the combination of p19Arf and nutlin-3. Conclusions To the best of our knowledge, this is the first study to apply both p19Arf and nutlin-3 for the stimulation of p53 activity. These results support the notion that a p53 responsive vector may prove to be an interesting gene transfer tool, especially when combined with p53-activating agents, for the treatment of tumors that retain wild-type p53. PMID:20569441
Basal p53 expression is indispensable for mesenchymal stem cell integrity.

PubMed

Boregowda, Siddaraju V; Krishnappa, Veena; Strivelli, Jacqueline; Haga, Christopher L; Booker, Cori N; Phinney, Donald G

2018-03-01

Marrow-resident mesenchymal stem cells (MSCs) serve as a functional component of the perivascular niche that regulates hematopoiesis. They also represent the main source of bone formed in adult bone marrow, and their bifurcation to osteoblast and adipocyte lineages plays a key role in skeletal homeostasis and aging. Although the tumor suppressor p53 also functions in bone organogenesis, homeostasis, and neoplasia, its role in MSCs remains poorly described. Herein, we examined the normal physiological role of p53 in primary MSCs cultured under physiologic oxygen levels. Using knockout mice and gene silencing we show that p53 inactivation downregulates expression of TWIST2, which normally restrains cellular differentiation to maintain wild-type MSCs in a multipotent state, depletes mitochondrial reactive oxygen species (ROS) levels, and suppresses ROS generation and PPARG gene and protein induction in response to adipogenic stimuli. Mechanistically, this loss of adipogenic potential skews MSCs toward an osteogenic fate, which is further potentiated by TWIST2 downregulation, resulting in highly augmented osteogenic differentiation. We also show that p53 - /- MSCs are defective in supporting hematopoiesis as measured in standard colony assays because of decreased secretion of various cytokines including CXCL12 and CSF1. Lastly, we show that transient exposure of wild-type MSCs to 21% oxygen upregulates p53 protein expression, resulting in increased mitochondrial ROS production and enhanced adipogenic differentiation at the expense of osteogenesis, and that treatment of cells with FGF2 mitigates these effects by inducing TWIST2. Together, these findings indicate that basal p53 levels are necessary to maintain MSC bi-potency, and oxygen-induced increases in p53 expression modulate cell fate and survival decisions. Because of the critical function of basal p53 in MSCs, our findings question the use of p53 null cell lines as MSC surrogates, and also implicate dysfunctional MSC responses in the pathophysiology of p53-related skeletal disorders.
EBNA3C regulates p53 through induction of Aurora kinase B

PubMed Central

Jha, Hem C.; Yang, Karren; El-Naccache, Darine W.; Sun, Zhiguo; Robertson, Erle S.

2015-01-01

In multicellular organisms p53 maintains genomic integrity through activation of DNA repair, and apoptosis. EBNA3C can down regulate p53 transcriptional activity. Aurora kinase (AK) B phosphorylates p53, which leads to degradation of p53. Aberrant expression of AK-B is a hallmark of numerous human cancers. Therefore changes in the activities of p53 due to AK-B and EBNA3C expression is important for understanding EBV-mediated cell transformation. Here we show that the activities of p53 and its homolog p73 are dysregulated in EBV infected primary cells which can contribute to increased cell transformation. Further, we showed that the ETS-1 binding site is crucial for EBNA3C-mediated up-regulation of AK-B transcription. Further, we determined the Ser 215 residue of p53 is critical for functional regulation by AK-B and EBNA3C and that the kinase domain of AK-B which includes amino acid residues 106, 111 and 205 was important for p53 regulation. AK-B with a mutation at residue 207 was functionally similar to wild type AK-B in terms of its kinase activities and knockdown of AK-B led to enhanced p73 expression independent of p53. This study explores an additional mechanism by which p53 is regulated by AK-B and EBNA3C contributing to EBV-induced B-cell transformation. PMID:25691063
Loss of p53 enhances the function of the endoplasmic reticulum through activation of the IRE1α/XBP1 pathway.

PubMed

Namba, Takushi; Chu, Kiki; Kodama, Rika; Byun, Sanguine; Yoon, Kyoung Wan; Hiraki, Masatsugu; Mandinova, Anna; Lee, Sam W

2015-08-21

Altered regulation of ER stress response has been implicated in a variety of human diseases, such as cancer and metabolic diseases. Excessive ER function contributes to malignant phenotypes, such as chemoresistance and metastasis. Here we report that the tumor suppressor p53 regulates ER function in response to stress. We found that loss of p53 function activates the IRE1α/XBP1 pathway to enhance protein folding and secretion through upregulation of IRE1α and subsequent activation of its target XBP1. We also show that wild-type p53 interacts with synoviolin (SYVN1)/HRD1/DER3, a transmembrane E3 ubiquitin ligase localized to ER during ER stress and removes unfolded proteins by reversing transport to the cytosol from the ER, and its interaction stimulates IRE1α degradation. Moreover, IRE1α inhibitor suppressed protein secretion, induced cell death in p53-deficient cells, and strongly suppressed the formation of tumors by p53-deficient human tumor cells in vivo compared with those that expressed wild-type p53. Therefore, our data imply that the IRE1α/XBP1 pathway serves as a target for therapy of chemoresistant tumors that express mutant p53.
Loss of p53 enhances the function of the endoplasmic reticulum through activation of the IRE1α/XBP1 pathway

PubMed Central

Kodama, Rika; Byun, Sanguine; Yoon, Kyoung Wan; Hiraki, Masatsugu; Mandinova, Anna; Lee, Sam W.

2015-01-01

Altered regulation of ER stress response has been implicated in a variety of human diseases, such as cancer and metabolic diseases. Excessive ER function contributes to malignant phenotypes, such as chemoresistance and metastasis. Here we report that the tumor suppressor p53 regulates ER function in response to stress. We found that loss of p53 function activates the IRE1α/XBP1 pathway to enhance protein folding and secretion through upregulation of IRE1α and subsequent activation of its target XBP1. We also show that wild-type p53 interacts with synoviolin (SYVN1)/HRD1/DER3, a transmembrane E3 ubiquitin ligase localized to ER during ER stress and removes unfolded proteins by reversing transport to the cytosol from the ER, and its interaction stimulates IRE1α degradation. Moreover, IRE1α inhibitor suppressed protein secretion, induced cell death in p53-deficient cells, and strongly suppressed the formation of tumors by p53-deficient human tumor cells in vivo compared with those that expressed wild-type p53. Therefore, our data imply that the IRE1α/XBP1 pathway serves as a target for therapy of chemoresistant tumors that express mutant p53. PMID:26254280
Enhanced radiosensitivity of malignant glioma cells after adenoviral p53 transduction.

PubMed

Broaddus, W C; Liu, Y; Steele, L L; Gillies, G T; Lin, P S; Loudon, W G; Valerie, K; Schmidt-Ullrich, R K; Fillmore, H L

1999-12-01

The goal of this study was to determine whether adenoviral vector-mediated expression of human wildtype p53 can enhance the radiosensitivity of malignant glioma cells that express native wild-type p53. The p53 gene is thought to function abnormally in the majority of malignant gliomas, although it has been demonstrated to be mutated in only approximately 30%. This has led to studies in which adenoviral transduction with wild-type human p53 has been investigated in an attempt to slow tumor cell growth. Recent studies suggest that reconstitution of wild-type p53 can render cells more susceptible to radiation-mediated death, primarily by p53-mediated apoptosis. Rat RT2 glioma cells were analyzed for native p53 status by reverse transcriptase-polymerase chain reaction and sequence analysis and for p53 expression by Western blot analysis. Clonogenic survival and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay were used to characterize RT2 cell radiosensitivity and apoptosis, respectively, with and without prior transduction with p53-containing and control adenoviral vectors. Animal survival length was monitored after intracerebral implantation with transduced and nontransduced RT2 cells, with and without cranial radiation. The RT2 cells were demonstrated to express native rat wild-type p53 and to markedly overexpress human p53 following adenoviral p53 transduction. The combination of p53 transduction followed by radiation resulted in marked decreases in RT2 cell survival and increases in apoptosis at radiation doses from 2 to 6 Gy. Animals receiving cranial radiation after intracerebral implantation with RT2 cells previously transduced with p53 survived significantly longer than control animals (p<0.01). The ability to enhance the radiosensitivity of malignant glioma cells that express wild-type p53 by using adenoviral transduction to induce overexpression of p53 offers hope for this approach as a therapeutic strategy, not only in human gliomas that express mutant p53, but also in those that express wild-type p53.

The influence of SV40 immortalization of human fibroblasts on p53-dependent radiation responses

NASA Technical Reports Server (NTRS)

Kohli, M.; Jorgensen, T. J.

1999-01-01

The simian virus 40 large tumor antigen (SV40 Tag) has been ascribed many functions critical to viral propagation, including binding to the mammalian tumor suppressor p53. Recent studies have demonstrated that SV40-transformed murine cells have functional p53. The status of p53 in SV40-immortalized human cells, however, has not been characterized. We have found that in response to ionizing radiation, p53-dependent p21 transactivation activity is present, albeit reduced, in SV40-immortalized cells and that this activity can be further reduced with either dominant negative p53 expression or higher SV40 Tag expression. Furthermore, overexpression of p53 in SV40-immortalized ataxia-telangiectasia (A-T) cells restores p53-dependent p21 induction to typical A-T levels. All SV40-immortalized cell lines exhibited an absence of G1 arrest. Moreover, all SV40-immortalized cell lines exhibited increased apoptosis relative to primary cells in response to ionizing radiation, suggesting that SV40 immortalization results in a unique phenotype with regard to DNA damage responses. Copyright 1999 Academic Press.
A mutant p53/let-7i-axis-regulated gene network drives cell migration, invasion and metastasis

PubMed Central

Subramanian, M; Francis, P; Bilke, S; Li, XL; Hara, T; Lu, X; Jones, MF; Walker, RL; Zhu, Y; Pineda, M; Lee, C; Varanasi, L; Yang, Y; Martinez, LA; Luo, J; Ambs, S; Sharma, S; Wakefield, LM; Meltzer, PS; Lal, A

2015-01-01

Most p53 mutations in human cancers are missense mutations resulting in a full-length mutant p53 protein. Besides losing tumor suppressor activity, some hotspot p53 mutants gain oncogenic functions. This effect is mediated in part, through gene expression changes due to inhibition of p63 and p73 by mutant p53 at their target gene promoters. Here, we report that the tumor suppressor microRNA let-7i is downregulated by mutant p53 in multiple cell lines expressing endogenous mutant p53. In breast cancer patients, significantly decreased let-7i levels were associated with missense mutations in p53. Chromatin immunoprecipitation and promoter luciferase assays established let-7i as a transcriptional target of mutant p53 through p63. Introduction of let-7i to mutant p53 cells significantly inhibited migration, invasion and metastasis by repressing a network of oncogenes including E2F5, LIN28B, MYC and NRAS. Our findings demonstrate that repression of let-7i expression by mutant p53 has a key role in enhancing migration, invasion and metastasis. PMID:24662829
Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents

PubMed Central

Michaelis, M; Rothweiler, F; Agha, B; Barth, S; Voges, Y; Löschmann, N; von Deimling, A; Breitling, R; Wilhelm Doerr, H; Rödel, F; Speidel, D; Cinatl, J

2012-01-01

Adaptation of wild-type p53 expressing UKF-NB-3 cancer cells to the murine double minute 2 inhibitor nutlin-3 causes de novo p53 mutations at high frequency (13/20) and multi-drug resistance. Here, we show that the same cells respond very differently when adapted to RITA, a drug that, like nutlin-3, also disrupts the p53/Mdm2 interaction. All of the 11 UKF-NB-3 sub-lines adapted to RITA that we established retained functional wild-type p53 although RITA induced a substantial p53 response. Moreover, all RITA-adapted cell lines remained sensitive to nutlin-3, whereas only five out of 10 nutlin-3-adapted cell lines retained their sensitivity to RITA. In addition, repeated adaptation of the RITA-adapted sub-line UKF-NB-3rRITA10 μM to nutlin-3 resulted in p53 mutations. The RITA-adapted UKF-NB-3 sub-lines displayed no or less pronounced resistance to vincristine, cisplatin, and irradiation than nutlin-3-adapted UKF-NB-3 sub-lines. Furthermore, adaptation to RITA was associated with fewer changes at the expression level of antiapoptotic factors than observed with adaptation to nutlin-3. Transcriptomic analyses indicated the RITA-adapted sub-lines to be more similar at the gene expression level to the parental UKF-NB-3 cells than nutlin-3-adapted UKF-NB-3 sub-lines, which correlates with the observed chemotherapy and irradiation sensitivity phenotypes. In conclusion, RITA-adapted cells retain functional p53, remain sensitive to nutlin-3, and display a less pronounced resistance phenotype than nutlin-3-adapted cells. PMID:22476102
Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents.

PubMed

Michaelis, M; Rothweiler, F; Agha, B; Barth, S; Voges, Y; Löschmann, N; von Deimling, A; Breitling, R; Doerr, H Wilhelm; Rödel, F; Speidel, D; Cinatl, J

2012-04-05

Adaptation of wild-type p53 expressing UKF-NB-3 cancer cells to the murine double minute 2 inhibitor nutlin-3 causes de novo p53 mutations at high frequency (13/20) and multi-drug resistance. Here, we show that the same cells respond very differently when adapted to RITA, a drug that, like nutlin-3, also disrupts the p53/Mdm2 interaction. All of the 11 UKF-NB-3 sub-lines adapted to RITA that we established retained functional wild-type p53 although RITA induced a substantial p53 response. Moreover, all RITA-adapted cell lines remained sensitive to nutlin-3, whereas only five out of 10 nutlin-3-adapted cell lines retained their sensitivity to RITA. In addition, repeated adaptation of the RITA-adapted sub-line UKF-NB-3(r)RITA(10 μM) to nutlin-3 resulted in p53 mutations. The RITA-adapted UKF-NB-3 sub-lines displayed no or less pronounced resistance to vincristine, cisplatin, and irradiation than nutlin-3-adapted UKF-NB-3 sub-lines. Furthermore, adaptation to RITA was associated with fewer changes at the expression level of antiapoptotic factors than observed with adaptation to nutlin-3. Transcriptomic analyses indicated the RITA-adapted sub-lines to be more similar at the gene expression level to the parental UKF-NB-3 cells than nutlin-3-adapted UKF-NB-3 sub-lines, which correlates with the observed chemotherapy and irradiation sensitivity phenotypes. In conclusion, RITA-adapted cells retain functional p53, remain sensitive to nutlin-3, and display a less pronounced resistance phenotype than nutlin-3-adapted cells.
Interplay between PTB and miR-1285 at the p53 3′UTR modulates the levels of p53 and its isoform Δ40p53α

PubMed Central

Katoch, Aanchal; George, Biju; Iyyappan, Amrutha; Khan, Debjit

2017-01-01

Abstract p53 and its translational isoform Δ40p53 are involved in many important cellular functions like cell cycle, cell proliferation, differentiation and metabolism. Expression of both the isoforms can be regulated at different steps. In this study, we explored the role of 3′UTR in regulating the expression of these two translational isoforms. We report that the trans acting factor, Polypyrimidine Tract Binding protein (PTB), also interacts specifically with 3′UTR of p53 mRNA and positively regulates expression of p53 isoforms. Our results suggest that there is interplay between miRNAs and PTB at the 3′UTR under normal and stress conditions like DNA damage. Interestingly, PTB showed some overlapping binding regions in the p53 3′UTR with miR-1285. In fact, knockdown of miR-1285 as well as expression of p53 3′UTR with mutated miR-1285 binding sites resulted in enhanced association of PTB with the 3′UTR, which provides mechanistic insights of this interplay. Taken together, the results provide a plausible molecular basis of how the interplay between miRNAs and the PTB protein at the 3′UTR can play pivotal role in fine tuning the expression of the two p53 isoforms. PMID:28973454
miR-24-3p Suppresses Malignant Behavior of Lacrimal Adenoid Cystic Carcinoma by Targeting PRKCH to Regulate p53/p21 Pathway.

PubMed

Zhang, Ming-Xue; Zhang, Jie; Zhang, Hong; Tang, Hua

2016-01-01

MicroRNA (miRNA) may function as an oncogene or a tumor suppressor in tumorigenesis. However, the mechanism of miRNAs in adenoid cystic carcinoma (ACC) is unclear. Here, we provide evidence that miR-24-3p was downreglated and functions as a tumor suppressor in human lacrimal adenoid cystic carcinoma by suppressing proliferation and migration/invasion while promoting apoptosis. miR-24-3p down-regulated protein kinase C eta (PRKCH) by binding to its untranslated region (3'UTR). PRKCH increased the of the cell growth and migration/invasion in ACC cells and suppressed the expression of p53 and p21 in both mRNA and protein level. The overexpression of miR-24-3p decreased its malignant phenotype. Ectopic expression of PRKCH counteracted the suppression of malignancy induced by miR-24-3p, as well as ectopic expression of miR-24-3p rescued the suppression of PRKCH in the p53/p21 pathway. These results suggest that miR-24-3p promotes the p53/p21 pathway by down-regulating PRKCH expression in lacrimal adenoid cystic carcinoma cells.
NF-Y loss triggers p53 stabilization and apoptosis in HPV18-positive cells by affecting E6 transcription.

PubMed

Benatti, Paolo; Basile, Valentina; Dolfini, Diletta; Belluti, Silvia; Tomei, Margherita; Imbriano, Carol

2016-07-19

The expression of the high risk HPV18 E6 and E7 oncogenic proteins induces the transformation of epithelial cells, through the disruption of p53 and Rb function. The binding of cellular transcription factors to cis-regulatory elements in the viral Upstream Regulatory Region (URR) stimulates E6/E7 transcription. Here, we demonstrate that the CCAAT-transcription factor NF-Y binds to a non-canonical motif within the URR and activates viral gene expression. In addition, NF-Y indirectly up-regulates HPV18 transcription through the transactivation of multiple cellular transcription factors. NF-YA depletion inhibits the expression of E6 and E7 genes and re-establishes functional p53. The activation of p53 target genes in turn leads to apoptotic cell death. Finally, we show that NF-YA loss sensitizes HPV18-positive cells toward the DNA damaging agent Doxorubicin, via p53-mediated transcriptional response.
Modulation of p53 cellular function and cell death by African swine fever virus.

PubMed

Granja, Aitor G; Nogal, María L; Hurtado, Carolina; Salas, José; Salas, María L; Carrascosa, Angel L; Revilla, Yolanda

2004-07-01

Modulation of the activity of tumor suppressor p53 is a key event in the replication of many viruses. We have studied the function of p53 in African swine fever virus (ASFV) infection by determining the expression and activity of this transcription factor in infected cells. p53 levels are increased at early times of infection and are maintained throughout the infectious cycle. The protein is transcriptionally active, stabilized by phosphorylation, and localized in the nucleus. p53 induces the expression of p21 and Mdm2. Strikingly, these two proteins are located at the cytoplasmic virus factories. The retention of Mdm2 at the factory may represent a viral mechanism to prevent p53 inactivation by the protein. The expression of apoptotic proteins, such as Bax or active caspase-3, is also increased following ASFV infection, although the increase in caspase-3 does not appear to be, at least exclusively, p53 dependent. Bax probably plays a role in the induction of apoptosis in the infected cells, as suggested by the release of cytochrome c from the mitochondria. The significance of p21 induction and localization is discussed in relation to the shutoff of cellular DNA synthesis that is observed in ASFV-infected cells.
Modulation of p53 Cellular Function and Cell Death by African Swine Fever Virus

PubMed Central

Granja, Aitor G.; Nogal, María L.; Hurtado, Carolina; Salas, José; Salas, María L.; Carrascosa, Angel L.; Revilla, Yolanda

2004-01-01

Modulation of the activity of tumor suppressor p53 is a key event in the replication of many viruses. We have studied the function of p53 in African swine fever virus (ASFV) infection by determining the expression and activity of this transcription factor in infected cells. p53 levels are increased at early times of infection and are maintained throughout the infectious cycle. The protein is transcriptionally active, stabilized by phosphorylation, and localized in the nucleus. p53 induces the expression of p21 and Mdm2. Strikingly, these two proteins are located at the cytoplasmic virus factories. The retention of Mdm2 at the factory may represent a viral mechanism to prevent p53 inactivation by the protein. The expression of apoptotic proteins, such as Bax or active caspase-3, is also increased following ASFV infection, although the increase in caspase-3 does not appear to be, at least exclusively, p53 dependent. Bax probably plays a role in the induction of apoptosis in the infected cells, as suggested by the release of cytochrome c from the mitochondria. The significance of p21 induction and localization is discussed in relation to the shutoff of cellular DNA synthesis that is observed in ASFV-infected cells. PMID:15194793
Reciprocal regulation of p53 and malic enzymes modulates metabolism and senescence.

PubMed

Jiang, Peng; Du, Wenjing; Mancuso, Anthony; Wellen, Kathryn E; Yang, Xiaolu

2013-01-31

Cellular senescence both protects multicellular organisms from cancer and contributes to their ageing. The pre-eminent tumour suppressor p53 has an important role in the induction and maintenance of senescence, but how it carries out this function remains poorly understood. In addition, although increasing evidence supports the idea that metabolic changes underlie many cell-fate decisions and p53-mediated tumour suppression, few connections between metabolic enzymes and senescence have been established. Here we describe a new mechanism by which p53 links these functions. We show that p53 represses the expression of the tricarboxylic-acid-cycle-associated malic enzymes ME1 and ME2 in human and mouse cells. Both malic enzymes are important for NADPH production, lipogenesis and glutamine metabolism, but ME2 has a more profound effect. Through the inhibition of malic enzymes, p53 regulates cell metabolism and proliferation. Downregulation of ME1 and ME2 reciprocally activates p53 through distinct MDM2- and AMP-activated protein kinase-mediated mechanisms in a feed-forward manner, bolstering this pathway and enhancing p53 activation. Downregulation of ME1 and ME2 also modulates the outcome of p53 activation, leading to strong induction of senescence, but not apoptosis, whereas enforced expression of either malic enzyme suppresses senescence. Our findings define physiological functions of malic enzymes, demonstrate a positive-feedback mechanism that sustains p53 activation, and reveal a connection between metabolism and senescence mediated by p53.
Differential effects on apoptosis induction in hepatocyte lines by stable expression of hepatitis B virus X protein

PubMed Central

Fiedler, Nicola; Quant, Ellen; Fink, Ludger; Sun, Jianguang; Schuster, Ralph; Gerlich, Wolfram H; Schaefer, Stephan

2006-01-01

AIM: Hepatitis B virus protein X (HBx) has been shown to be weakly oncogenic in vitro. The transforming activities of HBx have been linked with the inhibition of several functions of the tumor suppressor p53. We have studied whether HBx may have different effects on p53 depending on the cell type. METHODS: We used the human hepatoma cell line HepG2 and the immortalized murine hepatocyte line AML12 and analyzed stably transfected clones which expressed physiological amounts of HBx. P53 was induced by UV irradiation. RESULTS: The p53 induction by UV irradiation was unaffected by stable expression of HBx. However, the expression of the cyclin kinase inhibitor p21waf/cip/sdi which gets activated by p53 was affected in the HBx transformed cell line AML12-HBx9, but not in HepG2. In AML-HBx9 cells, p21waf/cip/sdi-protein expression and p21waf/cip/sdi transcription were deregulated. Furthermore, the process of apoptosis was affected in opposite ways in the two cell lines investigated. While stable expression of HBx enhanced apoptosis induced by UV irradiation in HepG2-cells, apoptosis was decreased in HBx transformed AML12-HBx9. P53 repressed transcription from the HBV enhancer I, when expressed from expression vectors or after induction of endogenous p53 by UV irradiation. Repression by endogenous p53 was partially reversible by stably expressed HBx in both cell lines. CONCLUSION: Stable expression of HBx leads to deregulation of apoptosis induced by UV irradiation depending on the cell line used. In an immortalized hepatocyte line HBx acted anti-apoptotic whereas expression in a carcinoma derived hepatocyte line HBx enhanced apoptosis. PMID:16937438
An advanced glycation end product (AGE)-receptor for AGEs (RAGE) axis restores adipogenic potential of senescent preadipocytes through modulation of p53 protein function.

PubMed

Chen, Chih-Yu; Abell, Allison Martorano; Moon, Yang Soo; Kim, Kee-Hong

2012-12-28

The impaired adipogenic potential of senescent preadipocytes is a hallmark of adipose aging and aging-related adipose dysfunction. Although advanced glycation end products (AGEs) derived from both foods and endogenous nonenzymatic glycation and AGE-associated signaling pathways are known to play a key role in aging and its related diseases, the role of AGEs in adipose aging remains elusive. We show a novel pro-adipogenic function of AGEs in replicative senescent preadipocytes and mouse embryonic fibroblasts, as well as primary preadipocytes isolated from aged mice. Using glycated bovine serum albumin (BSA) as a model protein of AGEs, we found that glycated BSA restores the impaired adipogenic potential of senescent preadipocytes in vitro and ex vivo. However, glycated BSA showed no effect on adipogenesis in nonsenescent preadipocytes. The AGE-induced receptor for AGE (RAGE) expression is required for the pro-adipogenic function of AGEs in senescent preadipocytes. RAGE is required for impairment of p53 expression and p53 function in regulating p21 expression in senescent preadipocytes. We also observed a direct binding between RAGE and p53 in senescent preadipocytes. Taken together, our findings reveal a novel pro-adipogenic function of the AGE-RAGE axis in p53-regulated adipogenesis of senescent preadipocytes, providing new insights into aging-dependent adiposity by diet-driven and/or endogenous glycated proteins.
An Advanced Glycation End Product (AGE)-Receptor for AGEs (RAGE) Axis Restores Adipogenic Potential of Senescent Preadipocytes through Modulation of p53 Protein Function*

PubMed Central

Chen, Chih-Yu; Abell, Allison Martorano; Moon, Yang Soo; Kim, Kee-Hong

2012-01-01

The impaired adipogenic potential of senescent preadipocytes is a hallmark of adipose aging and aging-related adipose dysfunction. Although advanced glycation end products (AGEs) derived from both foods and endogenous nonenzymatic glycation and AGE-associated signaling pathways are known to play a key role in aging and its related diseases, the role of AGEs in adipose aging remains elusive. We show a novel pro-adipogenic function of AGEs in replicative senescent preadipocytes and mouse embryonic fibroblasts, as well as primary preadipocytes isolated from aged mice. Using glycated bovine serum albumin (BSA) as a model protein of AGEs, we found that glycated BSA restores the impaired adipogenic potential of senescent preadipocytes in vitro and ex vivo. However, glycated BSA showed no effect on adipogenesis in nonsenescent preadipocytes. The AGE-induced receptor for AGE (RAGE) expression is required for the pro-adipogenic function of AGEs in senescent preadipocytes. RAGE is required for impairment of p53 expression and p53 function in regulating p21 expression in senescent preadipocytes. We also observed a direct binding between RAGE and p53 in senescent preadipocytes. Taken together, our findings reveal a novel pro-adipogenic function of the AGE-RAGE axis in p53-regulated adipogenesis of senescent preadipocytes, providing new insights into aging-dependent adiposity by diet-driven and/or endogenous glycated proteins. PMID:23150674
Expression of long non-coding RNA-HOTAIR in oral squamous cell carcinoma Tca8113 cells and its associated biological behavior

PubMed Central

Liu, Huawei; Li, Zhiyong; Wang, Chao; Feng, Lin; Huang, Haitao; Liu, Changkui; Li, Fengxia

2016-01-01

As a long noncoding RNA, HOX transcript antisense intergenic RNA (HOTAIR) is highly expressed in many types of tumors. However, its expression and function in oral squamous cell carcinoma (OSCC) cells and tissues remains largely unknown. We herein studied the biological functions of HOTAIR in OSCC Tca8113 cells. Real-time quantitative PCR showed that HOTAIR, p21 and p53 mRNA expressions in doxorubicin (DOX)-treated or γ-ray-irradiated Tca8113 cells were up-regulated. Knockdown of p53 expression inhibited DOX-induced HOTAIR up-regulation, suggesting that DNA damage-induced HOTAIR expression may be associated with p53. Transfection and CCK-8 assays showed that compared with the control group, overexpression of HOTAIR promoted the proliferation of Tca8113 cells, while interfering with its expression played an opposite role. Flow cytometry exhibited that HOTAIR overexpression decreased the rate of DOX-induced apoptosis. When HOTAIR expression was inhibited by siRNA, the proportions of cells in G2/M and S phases increased and decreased respectively. Meanwhile, the rate of DOX-induced apoptosis rose. DNA damage-induced HOTAIR expression facilitated the proliferation of Tca8113 cells and decreased their apoptosis. However, whether the up-regulation depends on p53 still needs in-depth studies. PMID:27904675
N-methylpurine DNA glycosylase inhibits p53-mediated cell cycle arrest and coordinates with p53 to determine sensitivity to alkylating agents

PubMed Central

Song, Shanshan; Xing, Guichun; Yuan, Lin; Wang, Jian; Wang, Shan; Yin, Yuxin; Tian, Chunyan; He, Fuchu; Zhang, Lingqiang

2012-01-01

Alkylating agents induce genome-wide base damage, which is repaired mainly by N-methylpurine DNA glycosylase (MPG). An elevated expression of MPG in certain types of tumor cells confers higher sensitivity to alkylation agents because MPG-induced apurinic/apyrimidic (AP) sites trigger more strand breaks. However, the determinant of drug sensitivity or insensitivity still remains unclear. Here, we report that the p53 status coordinates with MPG to play a pivotal role in such process. MPG expression is positive in breast, lung and colon cancers (38.7%, 43.4% and 25.3%, respectively) but negative in all adjacent normal tissues. MPG directly binds to the tumor suppressor p53 and represses p53 activity in unstressed cells. The overexpression of MPG reduced, whereas depletion of MPG increased, the expression levels of pro-arrest gene downstream of p53 including p21, 14-3-3σ and Gadd45 but not proapoptotic ones. The N-terminal region of MPG was specifically required for the interaction with the DNA binding domain of p53. Upon DNA alkylation stress, in p53 wild-type tumor cells, p53 dissociated from MPG and induced cell growth arrest. Then, AP sites were repaired efficiently, which led to insensitivity to alkylating agents. By contrast, in p53-mutated cells, the AP sites were repaired with low efficacy. To our knowledge, this is the first direct evidence to show that a DNA repair enzyme functions as a selective regulator of p53, and these findings provide new insights into the functional linkage between MPG and p53 in cancer therapy. PMID:22801474
N-methylpurine DNA glycosylase inhibits p53-mediated cell cycle arrest and coordinates with p53 to determine sensitivity to alkylating agents.

PubMed

Song, Shanshan; Xing, Guichun; Yuan, Lin; Wang, Jian; Wang, Shan; Yin, Yuxin; Tian, Chunyan; He, Fuchu; Zhang, Lingqiang

2012-08-01

Alkylating agents induce genome-wide base damage, which is repaired mainly by N-methylpurine DNA glycosylase (MPG). An elevated expression of MPG in certain types of tumor cells confers higher sensitivity to alkylation agents because MPG-induced apurinic/apyrimidic (AP) sites trigger more strand breaks. However, the determinant of drug sensitivity or insensitivity still remains unclear. Here, we report that the p53 status coordinates with MPG to play a pivotal role in such process. MPG expression is positive in breast, lung and colon cancers (38.7%, 43.4% and 25.3%, respectively) but negative in all adjacent normal tissues. MPG directly binds to the tumor suppressor p53 and represses p53 activity in unstressed cells. The overexpression of MPG reduced, whereas depletion of MPG increased, the expression levels of pro-arrest gene downstream of p53 including p21, 14-3-3σ and Gadd45 but not proapoptotic ones. The N-terminal region of MPG was specifically required for the interaction with the DNA binding domain of p53. Upon DNA alkylation stress, in p53 wild-type tumor cells, p53 dissociated from MPG and induced cell growth arrest. Then, AP sites were repaired efficiently, which led to insensitivity to alkylating agents. By contrast, in p53-mutated cells, the AP sites were repaired with low efficacy. To our knowledge, this is the first direct evidence to show that a DNA repair enzyme functions as a selective regulator of p53, and these findings provide new insights into the functional linkage between MPG and p53 in cancer therapy.
CP-31398 prevents the growth of p53-mutated colorectal cancer cells in vitro and in vivo.

PubMed

He, Xingxing; Kong, Xinjuan; Yan, Junwei; Yan, Jingjun; Zhang, Yunan; Wu, Qian; Chang, Ying; Shang, Haitao; Dou, Qian; Song, Yuhu; Liu, Fang

2015-03-01

Rescuing the function of mutant p53 protein is an attractive cancer therapeutic strategy. Small molecule CP-31398 was shown to restore mutant p53 tumor suppressor functions in cancer cells. Here, we determined the effects of CP-31398 on the growth of p53-mutated colorectal cancer (CRC) cells in vitro and in vivo. CRC cells which carry p53 mutation in codon 273 were treated with CP-31398 and the control, and the effects of CP-31398 on cell cycle, cell apoptosis, and proliferation were determined. The expression of p53-responsive downstream genes was evaluated by quantitative reverse transcriptase PCR (RT-PCR) and Western blot. CP-31398 was administrated into xenograft tumors created by the inoculation of HT-29 cells, and then the effect of CP-31398 on the growth of xenograft tumors was examined. CP-31398 induced p53 downstream target molecules in cultured HT-29 cells, which resulted in the inhibition of CRC cell growth assessed by the determination of cell cycle, apoptosis, and cell proliferation. In xenograft tumors, CP-31398 modulated the expression of Bax, Bcl-2, caspase 3, cyclin D, and Mdm2 and then blocked the growth of xenograft tumors. CP-31398 would be developed as a therapeutic candidate for p53-mutated CRC due to the restoration of mutant p53 tumor suppressor functions.
Regulation of monocarboxylate transporter MCT1 expression by p53 mediates inward and outward lactate fluxes in tumors.

PubMed

Boidot, Romain; Végran, Frédérique; Meulle, Aline; Le Breton, Aude; Dessy, Chantal; Sonveaux, Pierre; Lizard-Nacol, Sarab; Feron, Olivier

2012-02-15

The monocarboxylate transporter (MCT) family member MCT1 can transport lactate into and out of tumor cells. Whereas most oxidative cancer cells import lactate through MCT1 to fuel mitochondrial respiration, the role of MCT1 in glycolysis-derived lactate efflux remains less clear. In this study, we identified a direct link between p53 function and MCT1 expression. Under hypoxic conditions, p53 loss promoted MCT1 expression and lactate export produced by elevated glycolytic flux, both in vitro and in vivo. p53 interacted directly with the MCT1 gene promoter and altered MCT1 mRNA stabilization. In hypoxic p53(-/-) tumor cells, NF-κB further supported expression of MCT1 to elevate its levels. Following glucose deprivation, upregulated MCT1 in p53(-/-) cells promoted lactate import and favored cell proliferation by fuelling mitochondrial respiration. We also found that MCT1 expression was increased in human breast tumors harboring p53 mutations and coincident features of hypoxia, with higher MCT1 levels associated with poorer clinical outcomes. Together, our findings identify MCT1 as a target for p53 repression and they suggest that MCT1 elevation in p53-deficient tumors allows them to adapt to metabolic needs by facilitating lactate export or import depending on the glucose availability.
p53 is a major component of the transcriptional and apoptotic program regulated by PI 3-kinase/Akt/GSK3 signaling.

PubMed

Nayak, G; Cooper, G M

2012-10-11

The phosphatidylinositol (PI) 3-kinase/Akt signaling pathway has a prominent role in cell survival and proliferation, in part, by regulating gene expression at the transcriptional level. Previous work using global expression profiling identified FOXOs and the E-box-binding transcription factors MITF and USF1 as key targets of PI 3-kinase signaling that lead to the induction of proapoptotic and cell cycle arrest genes in response to inhibition of PI 3-kinase. In this study, we investigated the role of p53 downstream of PI 3-kinase signaling by analyzing the effects of inhibition of PI 3-kinase in Rat-1 cells, which have wild-type p53, compared with Rat-1 cells expressing a dominant-negative p53 mutant. Expression of dominant-negative p53 conferred partial resistance to apoptosis induced by inhibition of PI 3-kinase. Global gene expression profiling combined with computational and experimental analysis of transcription factor binding sites demonstrated that p53, along with FOXO, MITF and USF1, contributed to gene induction in response to PI 3-kinase inhibition. Activation of p53 was mediated by phosphorylation of the histone acetyltransferase Tip60 by glycogen synthase kinase (GSK) 3, leading to activation of p53 by acetylation. Many of the genes targeted by p53 were also targeted by FOXO and E-box-binding transcription factors, indicating that p53 functions coordinately with these factors to regulate gene expression downstream of PI 3-kinase/Akt/GSK3 signaling.
Jmjd5 functions as a regulator of p53 signaling during mouse embryogenesis.

PubMed

Ishimura, Akihiko; Terashima, Minoru; Tange, Shoichiro; Suzuki, Takeshi

2016-03-01

Genetic studies have shown that aberrant activation of p53 signaling leads to embryonic lethality. Maintenance of a fine balance of the p53 protein level is critical for normal development. Previously, we have reported that Jmjd5, a member of the Jumonji C (JmjC) family, regulates embryonic cell proliferation through the control of Cdkn1a expression. Since Cdkn1a is the representative p53-regulated gene, we have examined whether the expression of other p53 target genes is coincidentally upregulated with Cdkn1a in Jmjd5-deficient embryos. The expression of a subset of p53-regulated genes was increased in both Jmjd5 hypomorphic mouse embryonic fibroblasts (MEFs) and Jmjd5-deficient embryos at embryonic day 8.25 without the induced expression of Trp53. Intercrossing of Jmjd5-deficient mice with Trp53 knockout mice showed that the growth defect of Jmjd5 mutant cells was significantly recovered under a Trp53 null genetic background. Chromatin immunoprecipitation analysis in Jmjd5 hypomorphic MEFs indicated the increased recruitment of p53 at several p53 target gene loci, such as Cdkn1a, Pmaip1, and Mdm2. These results suggest that Jmjd5 is involved in the transcriptional regulation of a subset of p53-regulated genes, possibly through the control of p53 recruitment at the gene loci. In Jmjd5-deficient embryos, the enhanced recruitment of p53 might result in the abnormal activation of p53 signaling leading to embryonic lethality.

Interplay between PTB and miR-1285 at the p53 3'UTR modulates the levels of p53 and its isoform Δ40p53α.

PubMed

Katoch, Aanchal; George, Biju; Iyyappan, Amrutha; Khan, Debjit; Das, Saumitra

2017-09-29

p53 and its translational isoform Δ40p53 are involved in many important cellular functions like cell cycle, cell proliferation, differentiation and metabolism. Expression of both the isoforms can be regulated at different steps. In this study, we explored the role of 3'UTR in regulating the expression of these two translational isoforms. We report that the trans acting factor, Polypyrimidine Tract Binding protein (PTB), also interacts specifically with 3'UTR of p53 mRNA and positively regulates expression of p53 isoforms. Our results suggest that there is interplay between miRNAs and PTB at the 3'UTR under normal and stress conditions like DNA damage. Interestingly, PTB showed some overlapping binding regions in the p53 3'UTR with miR-1285. In fact, knockdown of miR-1285 as well as expression of p53 3'UTR with mutated miR-1285 binding sites resulted in enhanced association of PTB with the 3'UTR, which provides mechanistic insights of this interplay. Taken together, the results provide a plausible molecular basis of how the interplay between miRNAs and the PTB protein at the 3'UTR can play pivotal role in fine tuning the expression of the two p53 isoforms. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.
TSPAN12 is a critical factor for cancer–fibroblast cell contact-mediated cancer invasion

PubMed Central

Otomo, Ryo; Otsubo, Chihiro; Matsushima-Hibiya, Yuko; Miyazaki, Makoto; Tashiro, Fumio; Ichikawa, Hitoshi; Kohno, Takashi; Ochiya, Takahiro; Yokota, Jun; Nakagama, Hitoshi; Taya, Yoichi; Enari, Masato

2014-01-01

Communication between cancer cells and their microenvironment controls cancer progression. Although the tumor suppressor p53 functions in a cell-autonomous manner, it has also recently been shown to function in a non–cell-autonomous fashion. Although functional defects have been reported in p53 in stromal cells surrounding cancer, including mutations in the p53 gene and decreased p53 expression, the role of p53 in stromal cells during cancer progression remains unclear. We herein show that the expression of α-smooth muscle actin (α-SMA), a marker of cancer-associated fibroblasts (CAFs), was increased by the ablation of p53 in lung fibroblasts. CAFs enhanced the invasion and proliferation of lung cancer cells when cocultured with p53-depleted fibroblasts and required contact between cancer and stromal cells. A comprehensive analysis using a DNA chip revealed that tetraspanin 12 (TSPAN12), which belongs to the tetraspanin protein family, was derepressed by p53 knockdown. TSPAN12 knockdown in p53-depleted fibroblasts inhibited cancer cell proliferation and invasion elicited by coculturing with p53-depleted fibroblasts in vitro, and inhibited tumor growth in vivo. It also decreased CXC chemokine ligand 6 (CXCL6) secretion through the β-catenin signaling pathway, suggesting that cancer cell contact with TSPAN12 in fibroblasts transduced β-catenin signaling into fibroblasts, leading to the secretion of CXCL6 to efficiently promote invasion. These results suggest that stroma-derived p53 plays a pivotal role in epithelial cancer progression and that TSPAN12 and CXCL6 are potential targets for lung cancer therapy. PMID:25512506
Inactivation of p53 in pterygium influence miR-200a expression resulting in ZEB1/ZEB2 up-regulation and EMT processing.

PubMed

Wu, Chueh-Wei; Peng, Mei-Ling; Yeh, Ken-Tu; Tsai, Yi-Yu; Chiang, Chun-Chi; Cheng, Ya-Wen

2016-05-01

Loss of p53 function has been linked to progression of pterygium. MiR-200a is known to be controlled by p53. Here, we hypothesize that expression of miR-200a and downstream ZEB1/ZEB2 genes are regulated epithelial-mesenchymal transition (EMT) involved in the pathogenesis and recurrence of pterygium. For this study, 120 primary pterygial samples were collected. Immunohistochemistry and real-time RT-PCR were performed to determine the expression of p53, p53 down-stream EMT associated protein and miR-200a. The molecular correlation of p53, miR-200a and downstream genes were confirmed using primary pterygium cells (PECs). Expression of miR-200a in pterygium tissues was significantly lower than in conjunctiva controls (p = 0.015). Up-regulated miR-200a levels were positively correlated with and p53 protein expression (p < 0.001). The miR-200a downstream ZEB1/ZEB1 protein expression were negative correlated with miR-200a expression. Cell model studies demonstrated that miR-200a controlled the EMT of PECs through up-regulated ZEB1, ZEB2 and Snail gene expression. Our study demonstrated that inactivation of p53 in pterygium may influence miR-200a, resulting in ZEB1/ZEB2 up-regulation and EMT processing of pterygium. Therefore, we suggest that expression of miR-200a play an important role in EMT processing and recurrence of pterygium. Copyright © 2016 Elsevier Ltd. All rights reserved.
Selective sensitization to DNA-damaging agents in a human rhabdomyosarcoma cell line with inducible wild-type p53 overexpression.

PubMed

Gibson, A A; Harwood, F G; Tillman, D M; Houghton, J A

1998-01-01

Drug-induced cytotoxicity or apoptosis may be influenced by the expression of the p53 tumor suppressor gene and by the specific oncogene expressed, which may dictate the threshold at which a cytotoxic response may by induced. The objective of the study was to elucidate how DNA-damaging agents with different mechanisms of action were sensitized in the context of expression of the Pax3/FKHR fusion protein, a transformation event unique to alveolar rhabdomyosarcomas (ARMSs), and wild-type p53 (wtp53). A wtp53 cDNA was subcloned into the pGRE5-2/EBV vector with dexamethasone-inducible overexpression and transfected into Rh30 ARMS cells that express Pax3/FKHR and a mutant p53 phenotype. Following dexamethasone induction of wtp53 overexpression in a derived clone (Cl.#27), growth was slowed, and cells accumulated in G1. Functional wtp53 activity was demonstrated by selective transactivation of p50-2, a wtp53 chloramphenicol acetyltransferase reporter construct, and by up-regulated expression of endogenous p21Waf1. Data demonstrated p53-dependent sensitization (> or = 4-fold) to bleomycin, actinomycin D, and 5-fluorouracil and considerably less p53-dependence (< or = 2-fold) for doxorubicin, topotecan, etoposide, and cisplatin in Cl.#27 compared to an equivalent clone containing the pGRE5-EBV vector alone (VC#3). Data demonstrate that ARMS cells show a selective sensitization to DNA-damaging agents when wtp53 is overexpressed. The cytotoxic activity of agents that are not potentiated substantially must, therefore, depend upon p53-independent factors that relate to the mechanism of drug action.
Elevated expression of ribosomal protein genes L37, RPP-1, and S2 in the presence of mutant p53.

PubMed

Loging, W T; Reisman, D

1999-11-01

The wild-type p53 protein is a DNA-binding transcription factor that activates genes such as p21, MDM2, GADD45, and Bax that are required for the regulation of cell cycle progression or apoptosis in response to DNA damage. Mutant forms of p53, which are transforming oncogenes and are expressed at high levels in tumor cells, generally have a reduced binding affinity for the consensus DNA sequence. Interestingly, some p53 mutants that are no longer effective at binding to the consensus DNA sequence and transactivating promoters containing this target site have acquired the ability to transform cells in culture, in part through their ability to transactivate promoters of a number of genes that are not targets of the wild-type protein. Certain p53 mutants are therefore considered to be gain-of-function mutants and appear to be promoting proliferation or transforming cells through their ability to alter the expression of novel sets of genes. Our goal is to identify genes that have altered expression in the presence of a specific mutant p53 (Arg to Trp mutation at codon 248) protein. Through examining differential gene expression in cells devoid of p53 expression and in cells that express high levels of mutant p53 protein, we have identified three ribosomal protein genes that have elevated expression in response to mutant p53. Consistent with these findings, the overexpression of a number of ribosomal protein genes in human tumors and evidence for their contribution to oncogenic transformation have been reported previously, although the mechanism leading to this overexpression has remained elusive. We show results that indicate that expression of these specific ribosomal protein genes is increased in the presence of the R248W p53 mutant, which provides a mechanism for their overexpression in human tumors.
The expression of TP53 pathway-related proteins in ovarian carcinoma transplanted subcutaneously in nude mice.

PubMed

Zhang, S-R; Li, D-B; Xue, J-W

2018-03-01

Given the important functions of TP53 pathway in various biological processes, this study aimed to investigate the expression of TP53 pathway-related proteins in ovarian carcinoma transplanted subcutaneously in nude mice with and without the presence of p53 inhibitor and to explore possible roles of p53 in the development of ovarian cancer. Thirty BALB/c-nu female nude mice were randomly divided into model group, control group and p53 inhibitor group (Pftα group). There were 10 rats in each group. The nude mice were subcutaneously inoculated with human ovarian cancer cell line SKOV3, and the tumor growth was observed. Morphological changes of tumor tissue were observed by hematoxylin and eosin (HE) staining. The mRNA and protein levels of TP53 pathway related factors-p53, p21 and mouse double minute 2 homolog (MDM2) were detected by RT-PCR and Western blot. p53 inhibitor can increase the growth rate of subcutaneously transplanted tumor in nude mice. p53 inhibitor could decrease the expression of p53 and p21 at both mRNA and protein levels and increase the expression of MDM2 at both mRNA and protein levels in ovarian carcinoma transplanted subcutaneously in nude mice. TP53 pathway may play pivotal roles in the development of ovarian cancer and TP53 pathway may be a new target for the treatment of ovarian cancer.
PHTS, a novel putative tumor suppressor, is involved in the transformation reversion of HeLaHF cells independently of the p53 pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu Dehua; Fan, Wufang; Liu, Guohong

2006-04-01

HeLaHF is a non-transformed revertant of HeLa cells, likely resulting from the activation of a putative tumor suppressor(s). p53 protein was stabilized in this revertant and reactivated for certain transactivation functions. Although p53 stabilization has not conclusively been linked to the reversion, it is clear that the genes in p53 pathway are involved. The present study confirms the direct role of p53 in HeLaHF reversion by demonstrating that RNAi-mediated p53 silencing partially restores anchorage-independent growth potential of the revertant through the suppression of anoikis. In addition, we identified a novel gene, named PHTS, with putative tumor suppressor properties, and showedmore » that this gene is also involved in HeLaHF reversion independently of the p53 pathway. Expression profiling revealed that PHTS is one of the genes that is up-regulated in HeLaHF but not in HeLa. It encodes a putative protein with CD59-like domains. RNAi-mediated PHTS silencing resulted in the partial restoration of transformation (anchorage-independent growth) in HeLaHF cells, similar to that of p53 gene silencing, implying its tumor suppressor effect. However, the observed increased transformation potential by PHTS silencing appears to be due to an increased anchorage-independent proliferation rate rather than suppression of anoikis, unlike the effect of p53 silencing. p53 silencing did not affect PHTS gene expression, and vice versa, suggesting PHTS may function in a new and p53-independent tumor suppressor pathway. Furthermore, over-expression of PHTS in different cancer cell lines, in addition to HeLa, reduces cell growth likely via induced apoptosis, confirming the broad PHTS tumor suppressor properties.« less
Integrated High Throughput Analysis Identifies GSK3 as a Crucial Determinant of p53-Mediated Apoptosis in Lung Cancer Cells.

PubMed

Zhang, Yu; Zhu, Chenyang; Sun, Bangyao; Lv, Jiawei; Liu, Zhonghua; Liu, Shengwang; Li, Hai

2017-01-01

p53 dysfunction is frequently observed in lung cancer. Although restoring the tumour suppressor function of p53 is recently approved as a putative strategy for combating cancers, the lack of understanding of the molecular mechanism underlying p53-mediated lung cancer suppression has limited the application of p53-based therapies in lung cancer. Using RNA sequencing, we determined the transcriptional profile of human non-small cell lung carcinoma A549 cells after treatment with two p53-activating chemical compounds, nutlin and RITA, which could induce A549 cell cycle arrest and apoptosis, respectively. Bioinformatics analysis of genome-wide gene expression data showed that distinct transcription profiles were induced by nutlin and RITA and 66 pathways were differentially regulated by these two compounds. However, only two of these pathways, 'Adherens junction' and 'Axon guidance', were found to be synthetic lethal with p53 re-activation, as determined via integrated analysis of genome-wide gene expression profile and short hairpin RNA (shRNA) screening. Further functional protein association analysis of significantly regulated genes associated with these two synthetic lethal pathways indicated that GSK3 played a key role in p53-mediated A549 cell apoptosis, and then gene function study was performed, which revealed that GSK3 inhibition promoted p53-mediated A549 cell apoptosis in a p53 post-translational activity-dependent manner. Our findings provide us with new insights regarding the mechanism by which p53 mediates A549 apoptosis and may cast light on the development of more efficient p53-based strategies for treating lung cancer. © 201 The Author(s). Published by S. Karger AG, Basel.
An Efficient Method for Generation of Knockout Human Embryonic Stem Cells Using CRISPR/Cas9 System.

PubMed

Bohaciakova, Dasa; Renzova, Tereza; Fedorova, Veronika; Barak, Martin; Kunova Bosakova, Michaela; Hampl, Ales; Cajanek, Lukas

2017-11-01

Human embryonic stem cells (hESCs) represent a promising tool to study functions of genes during development, to model diseases, and to even develop therapies when combined with gene editing techniques such as CRISPR/CRISPR-associated protein-9 nuclease (Cas9) system. However, the process of disruption of gene expression by generation of null alleles is often inefficient and tedious. To circumvent these limitations, we developed a simple and efficient protocol to permanently downregulate expression of a gene of interest in hESCs using CRISPR/Cas9. We selected p53 for our proof of concept experiments. The methodology is based on series of hESC transfection, which leads to efficient downregulation of p53 expression even in polyclonal population (p53 Low cells), here proven by a loss of regulation of the expression of p53 target gene, microRNA miR-34a. We demonstrate that our approach achieves over 80% efficiency in generating hESC clonal sublines that do not express p53 protein. Importantly, we document by a set of functional experiments that such genetically modified hESCs do retain typical stem cells characteristics. In summary, we provide a simple and robust protocol to efficiently target expression of gene of interest in hESCs that can be useful for laboratories aiming to employ gene editing in their hESC applications/protocols.
Tumor suppressor p53 negatively regulates glycolysis stimulated by hypoxia through its target RRAD

PubMed Central

Wu, Rui; Liang, Yingjian; Lin, Meihua; Liu, Jia; Chan, Chang S.; Hu, Wenwei; Feng, Zhaohui

2014-01-01

Cancer cells display enhanced glycolysis to meet their energetic and biosynthetic demands even under normal oxygen concentrations. Recent studies have revealed that tumor suppressor p53 represses glycolysis under normoxia as a novel mechanism for tumor suppression. As the common microenvironmental stress for tumors, hypoxia drives the metabolic switch from the oxidative phosphorylation to glycolysis, which is crucial for survival and proliferation of cancer cells under hypoxia. The p53's role and mechanism in regulating glycolysis under hypoxia is poorly understood. Here, we found that p53 represses hypoxia-stimulated glycolysis in cancer cells through RRAD, a newly-identified p53 target. RRAD expression is frequently decreased in lung cancer. Ectopic expression of RRAD greatly reduces glycolysis whereas knockdown of RRAD promotes glycolysis in lung cancer cells. Furthermore, RRAD represses glycolysis mainly through inhibition of GLUT1 translocation to the plasma membrane. Under hypoxic conditions, p53 induces RRAD, which in turn inhibits the translocation of GLUT1 and represses glycolysis in lung cancer cells. Blocking RRAD by siRNA greatly abolishes p53's function in repressing glycolysis under hypoxia. Taken together, our results revealed an important role and mechanism of p53 in antagonizing the stimulating effect of hypoxia on glycolysis, which contributes to p53's function in tumor suppression. PMID:25114038
Proposed megakaryocytic regulon of p53: the genes engaged to control cell cycle and apoptosis during megakaryocytic differentiation

PubMed Central

Apostolidis, Pani A.; Lindsey, Stephan; Miller, William M.

2012-01-01

During endomitosis, megakaryocytes undergo several rounds of DNA synthesis without division leading to polyploidization. In primary megakaryocytes and in the megakaryocytic cell line CHRF, loss or knock-down of p53 enhances cell cycling and inhibits apoptosis, leading to increased polyploidization. To support the hypothesis that p53 suppresses megakaryocytic polyploidization, we show that stable expression of wild-type p53 in K562 cells (a p53-null cell line) attenuates the cells' ability to undergo polyploidization during megakaryocytic differentiation due to diminished DNA synthesis and greater apoptosis. This suggested that p53's effects during megakaryopoiesis are mediated through cell cycle- and apoptosis-related target genes, possibly by arresting DNA synthesis and promoting apoptosis. To identify candidate genes through which p53 mediates these effects, gene expression was compared between p53 knock-down (p53-KD) and control CHRF cells induced to undergo terminal megakaryocytic differentiation using microarray analysis. Among substantially downregulated p53 targets in p53-KD megakaryocytes were cell cycle regulators CDKN1A (p21) and PLK2, proapoptotic FAS, TNFRSF10B, CASP8, NOTCH1, TP53INP1, TP53I3, DRAM1, ZMAT3 and PHLDA3, DNA-damage-related RRM2B and SESN1, and actin component ACTA2, while antiapoptotic CKS1B, BCL2, GTSE1, and p53 family member TP63 were upregulated in p53-KD cells. Additionally, a number of cell cycle-related, proapoptotic, and cytoskeleton-related genes with known functions in megakaryocytes but not known to carry p53-responsive elements were differentially expressed between p53-KD and control CHRF cells. Our data support a model whereby p53 expression during megakaryopoiesis serves to control polyploidization and the transition from endomitosis to apoptosis by impeding cell cycling and promoting apoptosis. Furthermore, we identify a putative p53 regulon that is proposed to orchestrate these effects. PMID:22548738
Relationship between p53 dysfunction, CD38 expression, and IgV(H) mutation in chronic lymphocytic leukemia.

PubMed

Lin, Ke; Sherrington, Paul D; Dennis, Michael; Matrai, Zoltan; Cawley, John C; Pettitt, Andrew R

2002-08-15

Established adverse prognostic factors in chronic lymphocytic leukemia (CLL) include CD38 expression, relative lack of IgV(H) mutation, and defects of the TP53 gene. However, disruption of the p53 pathway can occur through mechanisms other than TP53 mutation, and we have recently developed a simple screening test that detects p53 dysfunction due to mutation of the genes encoding either p53 or ATM, a kinase that regulates p53. The present study was conducted to examine the predictive value of this test and to establish the relationship between p53 dysfunction, CD38 expression, and IgV(H) mutation. CLL cells from 71 patients were examined for IgV(H) mutation, CD38 expression, and p53 dysfunction (detected as an impaired p53/p21 response to ionizing radiation). Survival data obtained from 69 patients were analyzed according to each of these parameters. Relative lack of IgV(H) mutation (less than 5%; n = 45), CD38 positivity (antigen expressed on more than 20% of malignant cells; n = 19), and p53 dysfunction (n = 19) were independently confirmed as adverse prognostic factors. Intriguingly, all p53-dysfunctional patients and all but one of the CD38(+) patients had less [corrected] than 5% IgV(H) mutation. Moreover, patients with p53 dysfunction and/or CD38 positivity (n = 31) accounted for the short survival of the less mutated group. These findings indicate that the poor outcome associated with having less than 5% IgV(H) mutation may be due to the overrepresentation of high-risk patients with p53 dysfunction and/or CD38 positivity within this group, and that CD38(-) patients with functionally intact p53 may have a prolonged survival regardless of the extent of IgV(H) mutation.
Evolution of p53 transactivation specificity through the lens of a yeast-based functional assay.

PubMed

Lion, Mattia; Raimondi, Ivan; Donati, Stefano; Jousson, Olivier; Ciribilli, Yari; Inga, Alberto

2015-01-01

Co-evolution of transcription factors (TFs) with their respective cis-regulatory network enhances functional diversity in the course of evolution. We present a new approach to investigate transactivation capacity of sequence-specific TFs in evolutionary studies. Saccharomyces cerevisiae was used as an in vivo test tube and p53 proteins derived from human and five commonly used animal models were chosen as proof of concept. p53 is a highly conserved master regulator of environmental stress responses. Previous reports indicated conserved p53 DNA binding specificity in vitro, even for evolutionary distant species. We used isogenic yeast strains where p53-dependent transactivation was measured towards chromosomally integrated p53 response elements (REs). Ten REs were chosen to sample a wide range of DNA binding affinity and transactivation capacity for human p53 and proteins were expressed at two levels using an inducible expression system. We showed that the assay is amenable to study thermo-sensitivity of frog p53, and that chimeric constructs containing an ectopic transactivation domain could be rapidly developed to enhance the activity of proteins, such as fruit fly p53, that are poorly effective in engaging the yeast transcriptional machinery. Changes in the profile of relative transactivation towards the ten REs were measured for each p53 protein and compared to the profile obtained with human p53. These results, which are largely independent from relative p53 protein levels, revealed widespread evolutionary divergence of p53 transactivation specificity, even between human and mouse p53. Fruit fly and human p53 exhibited the largest discrimination among REs while zebrafish p53 was the least selective.
Evolution of p53 Transactivation Specificity through the Lens of a Yeast-Based Functional Assay

PubMed Central

Lion, Mattia; Raimondi, Ivan; Donati, Stefano; Jousson, Olivier; Ciribilli, Yari; Inga, Alberto

2015-01-01

Co-evolution of transcription factors (TFs) with their respective cis-regulatory network enhances functional diversity in the course of evolution. We present a new approach to investigate transactivation capacity of sequence-specific TFs in evolutionary studies. Saccharomyces cerevisiae was used as an in vivo test tube and p53 proteins derived from human and five commonly used animal models were chosen as proof of concept. p53 is a highly conserved master regulator of environmental stress responses. Previous reports indicated conserved p53 DNA binding specificity in vitro, even for evolutionary distant species. We used isogenic yeast strains where p53-dependent transactivation was measured towards chromosomally integrated p53 response elements (REs). Ten REs were chosen to sample a wide range of DNA binding affinity and transactivation capacity for human p53 and proteins were expressed at two levels using an inducible expression system. We showed that the assay is amenable to study thermo-sensitivity of frog p53, and that chimeric constructs containing an ectopic transactivation domain could be rapidly developed to enhance the activity of proteins, such as fruit fly p53, that are poorly effective in engaging the yeast transcriptional machinery. Changes in the profile of relative transactivation towards the ten REs were measured for each p53 protein and compared to the profile obtained with human p53. These results, which are largely independent from relative p53 protein levels, revealed widespread evolutionary divergence of p53 transactivation specificity, even between human and mouse p53. Fruit fly and human p53 exhibited the largest discrimination among REs while zebrafish p53 was the least selective. PMID:25668429
Loss of P53 regresses cardiac remodeling induced by pressure overload partially through inhibiting HIF1α signaling in mice.

PubMed

Li, Jiming; Zeng, Jingjing; Wu, Lianpin; Tao, Luyuan; Liao, Zhiyong; Chu, Maoping; Li, Lei

2018-06-22

The tumor suppressor p53 is recognized as the guardian of the genome in cell cycle and cell death. P53 expression increases as cardiac hypertrophy worsens to heart failure, suggesting that p53 may play important role in cardiac remodeling. In the present study, deletion of p53 in the mice heart would ameliorate cardiac hypertrophy induced by pressure overload. The role of p53 on heart was investigated using in vivo models. Cardiac hypertrophy in mice was induced by transverse aortic banding surgery. The extent of cardiac hypertrophy was examined by echocardiography, as well as pathological and molecular analyses of heart tissue. Global knockout of p53 in the mice reduced the hypertrophic response and markedly reduced cardiac apoptosis, and fibrosis. Ejection fraction of heart was also improved in hearts without p53 in response to pressure overload. Protein determination further suggested loss of p53 expression markedly increased Hypoxia-inducible factor 1-alpha (HIF1α) and vascular endothelial growth factor (VEGF) expression. The study indicated p53 deteriorated cardiac functions and cardiac hypertrophy, apoptosis, and fibrosis by partially inhibition of HIF1α and VEGF. Copyright © 2018 Elsevier Inc. All rights reserved.
Interleukin-6 increases matrix metalloproteinase-14 (MMP-14) levels via down-regulation of p53 to drive cancer progression.

PubMed

Cathcart, Jillian M; Banach, Anna; Liu, Alice; Chen, Jun; Goligorsky, Michael; Cao, Jian

2016-09-20

Matrix metalloproteinases (MMPs) play critical roles in cancer invasion and metastasis by digesting basement membrane and extracellular matrix (ECM). Much attention has focused on the enzymatic activities of MMPs; however, the regulatory mechanism of MMP expression remains elusive. By employing bioinformatics analysis, we identified a potential p53 response element within the MMP-14 promoter. Experimentally, we found that p53 can repress MMP-14 promoter activity, whereas deletion of this p53 response element abrogated this effect. Furthermore, we found that p53 expression decreases MMP-14 mRNA and protein levels and attenuates MMP-14-mediated cellular functions. Additional promoter analysis and chromatin immunoprecipitation studies identified a mechanism of regulation of MMP-14 expression by which p53 and transcription factor Sp1 competitively bind to the promoter. As the correlation between inflammation and cancer aggressiveness is well described, we next sought to evaluate if inflammatory cytokines could differentially affect p53 and MMP-14 levels. We demonstrate that interleukin-6 (IL-6) down-regulates p53 protein levels and thus results in a concomitant increase in MMP-14 expression, leading to enhanced cancer cell invasion and metastasis. Our data collectively indicate a novel mechanism of regulation of MMP-14 by a cascade of IL-6 and p53, demonstrating that the tumor microenvironment directly stimulates molecular changes in cancer cells to drive an invasive phenotype.
Somatotropinomas, but not nonfunctioning pituitary adenomas, maintain a functional apoptotic RET/Pit1/ARF/p53 pathway that is blocked by excess GDNF.

PubMed

Diaz-Rodriguez, Esther; Garcia-Rendueles, Angela R; Ibáñez-Costa, Alejandro; Gutierrez-Pascual, Ester; Garcia-Lavandeira, Montserrat; Leal, Alfonso; Japon, Miguel A; Soto, Alfonso; Venegas, Eva; Tinahones, Francisco J; Garcia-Arnes, Juan A; Benito, Pedro; Angeles Galvez, Maria; Jimenez-Reina, Luis; Bernabeu, Ignacio; Dieguez, Carlos; Luque, Raul M; Castaño, Justo P; Alvarez, Clara V

2014-11-01

Acromegaly is caused by somatotroph cell adenomas (somatotropinomas [ACROs]), which secrete GH. Human and rodent somatotroph cells express the RET receptor. In rodents, when normal somatotrophs are deprived of the RET ligand, GDNF (Glial Cell Derived Neurotrophic Factor), RET is processed intracellularly to induce overexpression of Pit1 [Transcription factor (gene : POUF1) essential for transcription of Pituitary hormones GH, PRL and TSHb], which in turn leads to p19Arf/p53-dependent apoptosis. Our purpose was to ascertain whether human ACROs maintain the RET/Pit1/p14ARF/p53/apoptosis pathway, relative to nonfunctioning pituitary adenomas (NFPAs). Apoptosis in the absence and presence of GDNF was studied in primary cultures of 8 ACROs and 3 NFPAs. Parallel protein extracts were analyzed for expression of RET, Pit1, p19Arf, p53, and phospho-Akt. When GDNF deprived, ACRO cells, but not NFPAs, presented marked level of apoptosis that was prevented in the presence of GDNF. Apoptosis was accompanied by RET processing, Pit1 accumulation, and p14ARF and p53 induction. GDNF prevented all these effects via activation of phospho-AKT. Overexpression of human Pit1 (hPit1) directly induced p19Arf/p53 and apoptosis in a pituitary cell line. Using in silico studies, 2 CCAAT/enhancer binding protein alpha (cEBPα) consensus-binding sites were found to be 100% conserved in mouse, rat, and hPit1 promoters. Deletion of 1 cEBPα site prevented the RET-induced increase in hPit1 promoter expression. TaqMan qRT-PCR (real time RT-PCR) for RET, Pit1, Arf, TP53, GDNF, steroidogenic factor 1, and GH was performed in RNA from whole ACRO and NFPA tumors. ACRO but not NFPA adenomas express RET and Pit1. GDNF expression in the tumors was positively correlated with RET and negatively correlated with p53. In conclusion, ACROs maintain an active RET/Pit1/p14Arf/p53/apoptosis pathway that is inhibited by GDNF. Disruption of GDNF's survival function might constitute a new therapeutic route in acromegaly.
Silencing of p53 RNA through transarterial delivery ameliorates renal tubular injury and downregulates GSK-3β expression after ischemia-reperfusion injury.

PubMed

Fujino, Takayuki; Muhib, Sharifi; Sato, Nobuyuki; Hasebe, Naoyuki

2013-12-01

p53, a pivotal protein in the apoptotic pathway, has been identified as a mediator of transcriptional responses to ischemia-reperfusion (IR) injury. The characteristics and functional significance of the p53 response in vivo are largely unknown in IR-induced kidney injury. Therapeutic opportunities of delivering small interfering RNA (siRNA) via venous injection have gained recognition; however, systemic adverse effects of siRNA therapy should be considered. To prevent IR-induced kidney injury, we tested the efficacy of transarterial administration of siRNA targeting p53 (p53 siRNA). Female C57BL/6 mice underwent unilateral renal artery ischemia for 30 min, followed by reperfusion. siRNA experiments utilized short hairpin (sh) RNA plasmid-based approaches. Transfection of shRNA was performed using cationic polymer transfection reagent. Injection of synthetic p53 shRNA into the left renal artery just after ischemia improved tubular injury, apoptosis, and the swelling of mitochondria in cells of the thick ascending limb of Henle (mTALH) at the outer medullary regions. Staining of upregulated p53 was colocalized with the inducible expression of glycogen synthase kinase-3β (GSK-3β) at mTALH after IR injury. p53 shRNA inhibited GSK-3β expression and restored β-catenin expression at mTALH. For IR-induced kidney injury, transarterial delivery of p53 siRNA is an effective pharmacological intervention. Targeting siRNA to p53 leads to an attenuation of apoptosis and mitochondrial damage through the downregulation of GSK-3β expression and upregulation of β-catenin. Local delivery of vectors such as p53 siRNA through a transaortic catheter is clinically useful in reducing the adverse effect of siRNA-related therapy.
Identification of two novel functional p53 responsive elements in the Herpes Simplex Virus-1 genome

PubMed Central

Hsieh, Jui-Cheng; Kuta, Ryan; Armour, Courtney R.; Boehmer, Paul E.

2014-01-01

Analysis of the herpes simplex virus-1 (HSV-1) genome reveals two candidate p53 responsive elements (p53RE), located in proximity to the replication origins oriL and oriS, referred to as p53RE-L and p53RE-S, respectively. The sequences of p53RE-L and p53RE-S conform to the p53 consensus site and are present in HSV-1 strains KOS, 17, and F. p53 binds to both elements in vitro and in virus-infected cells. Both p53RE-L and p53RE-S are capable of conferring p53-dependent transcriptional activation onto a heterologous reporter gene. Importantly, expression of the essential immediate early viral transactivator ICP4 and the essential DNA replication protein ICP8, that are adjacent to p53RE-S and p53RE-L, are repressed in a p53-dependent manner. Taken together, this study identifies two novel functional p53RE in the HSV-1 genome and suggests a complex mechanism of viral gene regulation by p53 which may determine progression of the lytic viral replication cycle or the establishment of latency. PMID:25010269
p53 isoform Δ113p53/Δ133p53 promotes DNA double-strand break repair to protect cell from death and senescence in response to DNA damage.

PubMed

Gong, Lu; Gong, Hongjian; Pan, Xiao; Chang, Changqing; Ou, Zhao; Ye, Shengfan; Yin, Le; Yang, Lina; Tao, Ting; Zhang, Zhenhai; Liu, Cong; Lane, David P; Peng, Jinrong; Chen, Jun

2015-03-01

The inhibitory role of p53 in DNA double-strand break (DSB) repair seems contradictory to its tumor-suppressing property. The p53 isoform Δ113p53/Δ133p53 is a p53 target gene that antagonizes p53 apoptotic activity. However, information on its functions in DNA damage repair is lacking. Here we report that Δ113p53 expression is strongly induced by γ-irradiation, but not by UV-irradiation or heat shock treatment. Strikingly, Δ113p53 promotes DNA DSB repair pathways, including homologous recombination, non-homologous end joining and single-strand annealing. To study the biological significance of Δ113p53 in promoting DNA DSB repair, we generated a zebrafish Δ113p53(M/M) mutant via the transcription activator-like effector nuclease technique and found that the mutant is more sensitive to γ-irradiation. The human ortholog, Δ133p53, is also only induced by γ-irradiation and functions to promote DNA DSB repair. Δ133p53-knockdown cells were arrested at the G2 phase at the later stage in response to γ-irradiation due to a high level of unrepaired DNA DSBs, which finally led to cell senescence. Furthermore, Δ113p53/Δ133p53 promotes DNA DSB repair via upregulating the transcription of repair genes rad51, lig4 and rad52 by binding to a novel type of p53-responsive element in their promoters. Our results demonstrate that Δ113p53/Δ133p53 is an evolutionally conserved pro-survival factor for DNA damage stress by preventing apoptosis and promoting DNA DSB repair to inhibit cell senescence. Our data also suggest that the induction of Δ133p53 expression in normal cells or tissues provides an important tolerance marker for cancer patients to radiotherapy.

Expression of miR-34c in response to overexpression of Boule and Stra8 in dairy goat male germ line stem cells (mGSCs).

PubMed

Li, Mingzhao; Yu, Meng; Liu, Chao; Zhu, Haijing; Hua, Jinlian

2013-06-01

Reproduction is required for the survival of all mammalian animals. Spermatogenesis is an essential and complex developmental process that ultimately results in production of haploid spermatozoa. Recent studies demonstrated that Boule and stimulated by retinoic acid 8 (Stra8) played important roles in initiation meiosis in male germ cells. miR-34c is indispensable in the late steps of spermatogenesis; remarkably, the main function of miR-34c is to reduce cell proliferation potentiality and promote cellular apoptosis. The objectives of this study were to investigate the expression patterns of Boule, Stra8, P53 and miR-34c in dairy goat testis and their relationship in male germ line stem cells (mGSCs). The results first revealed the expression patterns of Boule, Stra8, P53 and miR-34c in 30 dpp, 90 dpp and adult testes of dairy goats. The expression levels of Boule, Stra8, P53 and miR-34c in adult dairy goat testes were significantly higher than that of 30 dpp. Overexpression of Boule and Stra8 promoted the expression of miR-34c in dairy goat mGSCs. In our previous study, we showed that miR-34c was P53 dependent in mGSCs. These results have shown that the up-regulation of miR-34c was not due to P53 protein activation but which might be caused by the up-regulation of Boule and Stra8 promoting the advance of meiosis. In addition, we found retinoic acid would decrease the expression of P53 and miR-34c, however, did not change the expression of c-Myc greatly. It suggested that the function of driving differentiation of dairy goat mGSCs by retinoic acid might not be caused by P53. Copyright © 2013 John Wiley & Sons, Ltd.
Mutant p53 perturbs DNA replication checkpoint control through TopBP1 and Treslin.

PubMed

Liu, Kang; Lin, Fang-Tsyr; Graves, Joshua D; Lee, Yu-Ju; Lin, Weei-Chin

2017-05-09

Accumulating evidence supports the gain-of-function of mutant forms of p53 (mutp53s). However, whether mutp53 directly perturbs the DNA replication checkpoint remains unclear. Previously, we have demonstrated that TopBP1 forms a complex with mutp53s and mediates their gain-of-function through NF-Y and p63/p73. Akt phosphorylates TopBP1 and induces its oligomerization, which inhibits its ATR-activating function. Here we show that various contact and conformational mutp53s bypass Akt to induce TopBP1 oligomerization and attenuate ATR checkpoint response during replication stress. The effect on ATR response caused by mutp53 can be exploited in a synthetic lethality strategy, as depletion of another ATR activator, DNA2, in mutp53-R273H-expressing cancer cells renders cells hypersensitive to cisplatin. Expression of mutp53-R273H also makes cancer cells more sensitive to DNA2 depletion or DNA2 inhibitors. In addition to ATR-activating function during replication stress, TopBP1 interacts with Treslin in a Cdk-dependent manner to initiate DNA replication during normal growth. We find that mutp53 also interferes with TopBP1 replication function. Several contact, but not conformational, mutp53s enhance the interaction between TopBP1 and Treslin and promote DNA replication despite the presence of a Cdk2 inhibitor. Together, these data uncover two distinct mechanisms by which mutp53 enhances DNA replication: ( i ) Both contact and conformational mutp53s can bind TopBP1 and attenuate the checkpoint response to replication stress, and ( ii ) during normal growth, contact (but not conformational) mutp53s can override the Cdk2 requirement to promote replication by facilitating the TopBP1/Treslin interaction.
MicroRNA-214 Promotes Apoptosis in Canine Hemangiosarcoma by Targeting the COP1-p53 Axis.

PubMed

Heishima, Kazuki; Mori, Takashi; Sakai, Hiroki; Sugito, Nobuhiko; Murakami, Mami; Yamada, Nami; Akao, Yukihiro; Maruo, Kohji

2015-01-01

MicroRNA-214 regulates both angiogenic function in endothelial cells and apoptosis in various cancers. However, the regulation and function of miR-214 is unclear in canine hemangiosarcoma, which is a spontaneous model of human angiosarcoma. The expression and functional roles of miR-214 in canine hemangiosarcoma were presently explored by performing miRNA TaqMan qRT-PCR and transfecting cells with synthetic microRNA. Here, we report that miR-214 was significantly down-regulated in the cell lines used and in clinical samples of canine hemangiosarcoma. Restoration of miR-214 expression reduced cell growth and induced apoptosis in canine hemangiosarcoma cell lines through transcriptional activation of p53-regulated genes although miR-214 had a slight effect of growth inhibition on normal endothelial cells. We identified COP1, which is a critical negative regulator of p53, as a novel direct target of miR-214. COP1 was overexpressed and the specific COP1 knockdown induced apoptosis through transcriptional activation of p53-regulated genes as well as did miR-214-transfection in HSA cell lines. Furthermore, p53 knockdown abolished the miR-214-COP1-mediated apoptosis; thus, miR-214 and COP1 regulated apoptosis through controlling p53 in HSA. In conclusion, miR-214 functioned as a tumor suppressor in canine hemangiosarcoma by inducing apoptosis through recovering the function of p53. miR-214 down-regulation and COP1 overexpression is likely to contribute to tumorigenesis of HSA. Therefore, targeting miR-214-COP1-p53 axis would possibly be a novel effective strategy for treatment of canine hemangiosarcoma and capable of being applied to the development of novel therapeutics for human angiosarcoma.
Pattern of Expression of p53, Its Family Members, and Regulators during Early Ocular Development and in the Post-Mitotic Retina

PubMed Central

Vuong, Linda; Brobst, Daniel E.; Saadi, Anisse; Ivanovic, Ivana; Al-Ubaidi, Muayyad R.

2012-01-01

Purpose. Because of its role in cell cycle regulation and apoptosis, p53 may be involved in maintaining the post-mitotic state of the adult eye. To shed light on the role of p53 in retinal development and maintenance, this study investigated the pattern of expression of p53, its family members, and its regulators during the development of the mouse eye. Methods. Relative quantitative real-time PCR (qRT-PCR) was used to determine the steady-state levels of target transcripts in RNA extracted from wild-type mouse whole eyes or retinas between embryonic day (E) 15 and post-natal day (P) 30. Immunoblotting was used to compare the steady-state levels of the protein to that of the transcript. Results. Transcript and protein levels for p53 in the eye were highest at E17 and E18, respectively. However, both p53 transcript and protein levels dropped precipitously thereafter, and no protein was detected on immunoblots after P3. Expression patterns of p63, p73, Mdm2, Mdm4, and Yy1 did not follow that of p53. Immunohistochemistry analysis of the developing eye showed that both p53 and Mdm2 are abundantly expressed at E18 in all layers of the retinal neuroblast. Conclusions. Downregulation of p53 in the post-mitotic retina suggests that, although p53 may be involved in ocular and retinal development, it may play a minimal role in healthy adult retinal function. PMID:22714890
Cytoplasmic sequestration of the tumor suppressor p53 by a heat shock protein 70 family member, mortalin, in human colorectal adenocarcinoma cell lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gestl, Erin E., E-mail: egestl@wcupa.edu; Anne Boettger, S., E-mail: aboettger@wcupa.edu

2012-06-29

Highlights: Black-Right-Pointing-Pointer Eight human colorectal cell lines were evaluated for p53 and mortalin localization. Black-Right-Pointing-Pointer Six cell lines displayed cytoplasmic sequestration of the tumor suppressor p53. Black-Right-Pointing-Pointer Direct interaction between mortalin and p53 was shown in five cell lines. Black-Right-Pointing-Pointer Cell lines positive for p53 sequestration yielded elevated p53 expression levels. Black-Right-Pointing-Pointer This study yields the first evidence of cytoplasmic sequestration p53 by mortalin. -- Abstract: While it is known that cytoplasmic retention of p53 occurs in many solid tumors, the mechanisms responsible for this retention have not been positively identified. Since heatshock proteins like mortalin have been associated withmore » p53 inactivation in other tumors, the current study sought to characterize this potential interaction in never before examined colorectal adenocarcinoma cell lines. Six cell lines, one with 3 different fractions, were examined to determine expression of p53 and mortalin and characterize their cellular localization. Most of these cell lines displayed punctate p53 and mortalin localization in the cell cytoplasm with the exception of HCT-8 and HCT116 379.2 cells, where p53 was not detected. Nuclear p53 was only observed in HCT-116 40-16, LS123, and HT-29 cell lines. Mortalin was only localized in the cytoplasm in all cell lines. Co-immunoprecipitation and immunohistochemistry revealed that p53 and mortalin were bound and co-localized in the cytoplasmic fraction of four cell lines, HCT-116 (40-16 and 386; parental and heterozygous fractions respectively of the same cell line), HT-29, LS123 and LoVo, implying that p53 nuclear function is limited in those cell lines by being restricted to the cytoplasm. Mortalin gene expression levels were higher than gene expression levels of p53 in all cell lines. Cell lines with cytoplasmic sequestration of p53, however, also displayed elevated p53 gene expression levels compared to cell lines without p53 sequestration. Our data reveal the characteristic cytoplasmic sequestration of p53 by the heat shock protein mortalin in human colorectal adenocarcinoma cell lines, as is the case for other cancers, such as glioblastomas and hepatocellular carcinomas.« less
Overexpression of p53 mRNA in colorectal cancer and its relationship to p53 gene mutation.

PubMed Central

el-Mahdani, N.; Vaillant, J. C.; Guiguet, M.; Prévot, S.; Bertrand, V.; Bernard, C.; Parc, R.; Béréziat, G.; Hermelin, B.

1997-01-01

We analysed the frequency of p53 mRNA overexpression in a series of 109 primary colorectal carcinomas and its association with p53 gene mutation, which has been correlated with short survival. Sixty-nine of the 109 cases (63%) demonstrated p53 mRNA overexpression, without any correlation with stage or site of disease. Comparison with p53 gene mutation indicated that, besides cases in which p53 gene mutation and p53 mRNA overexpression were either both present (40 cases) or both absent (36 cases), there were also cases in which p53 mRNA was overexpressed in the absence of any mutation (29 cases) and those with a mutant gene in which the mRNA was not overexpressed (four cases). Moreover, the mutant p53 tumours exhibited an increase of p53 mRNA expression, which was significantly higher in tumours expressing the mutated allele alone than in tumours expressing both wild- and mutated-type alleles. These data (1) show that p53 mRNA overexpression is a frequent event in colorectal tumours and is not predictive of the status of the gene, i.e. whether or not a mutation is present; (2) provide further evidence that p53 protein overexpression does not only result from an increase in the half-life of mutated p53 and suggest that inactivation of the p53 function in colorectal cancers involves at least two distinct mechanisms, including p53 overexpression and/or mutation; and (3) suggest that p53 mRNA overexpression is an early event, since it is not correlated with Dukes stage. PMID:9052405
p53 regulates the mevalonate pathway in human glioblastoma multiforme

PubMed Central

Laezza, C; D'Alessandro, A; Di Croce, L; Picardi, P; Ciaglia, E; Pisanti, S; Malfitano, A M; Comegna, M; Faraonio, R; Gazzerro, P; Bifulco, M

2015-01-01

The mevalonate (MVA) pathway is an important metabolic pathway implicated in multiple aspects of tumorigenesis. In this study, we provided evidence that p53 induces the expression of a group of enzymes of the MVA pathway including 3′-hydroxy-3′-methylglutaryl-coenzyme A reductase, MVA kinase, farnesyl diphosphate synthase and farnesyl diphosphate farnesyl transferase 1, in the human glioblastoma multiforme cell line, U343 cells, and in normal human astrocytes, NHAs. Genetic and pharmacologic perturbation of p53 directly influences the expression of these genes. Furthermore, p53 is recruited to the gene promoters in designated p53-responsive elements, thereby increasing their transcription. Such effect was abolished by site-directed mutagenesis in the p53-responsive element of promoter of the genes. These findings highlight another aspect of p53 functions unrelated to tumor suppression and suggest p53 as a novel regulator of the MVA pathway providing insight into the role of this pathway in cancer progression. PMID:26469958
Combined CSL and p53 downregulation promotes cancer-associated fibroblast activation

PubMed Central

Procopio, Maria-Giuseppina; Laszlo, Csaba; Labban, Dania Al; Kim, Dong Eun; Bordignon, Pino; Jo, Seunghee; Goruppi, Sandro; Menietti, Elena; Ostano, Paola; Ala, Ugo; Provero, Paolo; Hoetzenecker, Wolfram; Neel, Victor; Kilarski, Witek; Swartz, Melody A.; Brisken, Cathrin; Lefort, Karine; Dotto, G. Paolo

2015-01-01

Stromal fibroblast senescence has been linked to aging-associated cancer risk. However, density and proliferation of cancer-associated fibroblasts (CAF) are frequently increased. Loss or down-modulation of the Notch effector CSL/RBP-Jκ in dermal fibroblasts is sufficient for CAF activation and ensuing keratinocyte-derived tumors. We report that CSL silencing induces senescence of primary fibroblasts from dermis, oral mucosa, breast and lung. CSL functions in these cells as direct repressor of multiple senescence- and CAF-effector genes. It also physically interacts with p53, repressing its activity. CSL is down-modulated in stromal fibroblasts of premalignant skin actinic keratosis lesions and squamous cell carcinomas (SCC), while p53 expression and function is down-modulated only in the latter, with paracrine FGF signaling as likely culprit. Concomitant loss of CSL and p53 overcomes fibroblast senescence, enhances expression of CAF effectors and promotes stromal and cancer cell expansion. The findings support a CAF activation/stromal co-evolution model under convergent CSL/p53 control. PMID:26302407
The double life of MULE in preeclamptic and IUGR placentae.

PubMed

Rolfo, A; Garcia, J; Todros, T; Post, M; Caniggia, I

2012-05-03

The E3 ubiquitin ligase MULE (Mcl-1 Ubiquitin Ligases E3) targets myeloid cell leukemia factor 1 (Mcl-1) and tumor suppressor p53 for proteasomal degradation. Although Mcl-1 and p53 have been implicated in trophoblast cell death in preeclampsia (PE) and intrauterine growth restriction (IUGR), the mechanisms regulating their expression in the human placenta remains elusive. Herein, we investigated MULE's involvement in regulating Mcl-1 and p53 degradation during normal and abnormal (PE, IUGR) placental development. MULE expression peaked at 5-7 weeks of gestation, when oxygen tension is low and inversely correlated with that of Mcl-1 and p53. MULE efficiently bound to Mcl-1 and p53 and regulated their ubiquitination during placental development. Exposure of first trimester villous explants to 3% O(2) resulted in elevated MULE expression compared with 20% O(2). Low-oxygen-induced MULE expression in JEG3 choriocarcinoma cells was abolished by hypoxia-inducible factor (HIF)-1α siRNA. MULE was overexpressed in both PE and IUGR placentae. In PE, MULE preferentially targeted p53 for degradation, allowing accumulation of pro-apoptotic Mcl-1 isoforms. In IUGR, however, MULE targeted pro-survival Mcl-1, allowing p53 to accumulate and exert its apoptotic function. These data demonstrate that oxygen regulates Mcl-1 and p53 stability during placentation via HIF-1-controlled MULE expression. The different preferential targets of MULE in PE and IUGR placentae classify early-onset PE and IUGR as distinct molecular pathologies.
Inactivation of p53 by Human T-Cell Lymphotropic Virus Type 1 Tax Requires Activation of the NF-κB Pathway and Is Dependent on p53 Phosphorylation

PubMed Central

Pise-Masison, Cynthia A.; Mahieux, Renaud; Jiang, Hua; Ashcroft, Margaret; Radonovich, Michael; Duvall, Janet; Guillerm, Claire; Brady, John N.

2000-01-01

p53 plays a key role in guarding cells against DNA damage and transformation. We previously demonstrated that the human T-cell lymphotropic virus type 1 (HTLV-1) Tax can inactivate p53 transactivation function in lymphocytes. The present study demonstrates that in T cells, Tax-induced p53 inactivation is dependent upon NF-κB activation. Analysis of Tax mutants demonstrated that Tax inactivation of p53 function correlates with the ability of Tax to induce NF-κB but not p300 binding or CREB transactivation. The Tax-induced p53 inactivation can be overcome by overexpression of a dominant IκB mutant. Tax-NF-κB-induced p53 inactivation is not due to p300 squelching, since overexpression of p300 does not recover p53 activity in the presence of Tax. Further, using wild-type and p65 knockout mouse embryo fibroblasts (MEFs), we demonstrate that the p65 subunit of NF-κB is critical for Tax-induced p53 inactivation. While Tax can inactivate endogenous p53 function in wild-type MEFs, it fails to inactivate p53 function in p65 knockout MEFs. Importantly, Tax-induced p53 inactivation can be restored by expression of p65 in the knockout MEFs. Finally, we present evidence that phosphorylation of serines 15 and 392 correlates with inactivation of p53 by Tax in T cells. This study provides evidence that the divergent NF-κB proliferative and p53 cell cycle arrest pathways may be cross-regulated at several levels, including posttranslational modification of p53. PMID:10779327
Synthesis of cytochrome C oxidase 2: a p53-dependent metabolic regulator that promotes respiratory function and protects glioma and colon cancer cells from hypoxia-induced cell death.

PubMed

Wanka, C; Brucker, D P; Bähr, O; Ronellenfitsch, M; Weller, M; Steinbach, J P; Rieger, J

2012-08-16

P53 has an important role in the processing of starvation signals. P53-dependent molecular mediators of the Warburg effect reduce glucose consumption and promote mitochondrial function. We therefore hypothesized that the retention of wild-type p53 characteristic of primary glioblastomas limits metabolic demands induced by deregulated signal transduction in the presence of hypoxia and nutrient depletion. Here we report that short hairpin RNA-mediated gene suppression of wild-type p53 or ectopic expression of mutant temperature-sensitive dominant-negative p53(V135A) increased glucose consumption and lactate production, decreased oxygen consumption and enhanced hypoxia-induced cell death in p53 wild-type human glioblastoma cells. Similarly, genetic knockout of p53 in HCT116 colon carcinoma cells resulted in reduced respiration and hypersensitivity towards hypoxia-induced cell death. Further, wild-type p53 gene silencing reduced the expression of synthesis of cytochrome c oxidase 2 (SCO2), an effector necessary for respiratory chain function. An SCO2 transgene reverted the metabolic phenotype and restored resistance towards hypoxia in p53-depleted and p53 mutant glioma cells in a rotenone-sensitive manner, demonstrating that this effect was dependent on intact oxidative phosphorylation. Supplementation with methyl-pyruvate, a mitochondrial substrate, rescued p53 wild-type but not p53 mutant cells from hypoxic cell death, demonstrating a p53-mediated selective aptitude to metabolize mitochondrial substrates. Further, SCO2 gene silencing in p53 wild-type glioma cells sensitized these cells towards hypoxia. Finally, lentiviral gene suppression of SCO2 significantly enhanced tumor necrosis in a subcutaneous HCT116 xenograft tumor model, compatible with impaired energy metabolism in these cells. These findings demonstrate that glioma and colon cancer cells with p53 wild-type status can skew the Warburg effect and thereby reduce their vulnerability towards tumor hypoxia in an SCO2-dependent manner. Targeting SCO2 may therefore represent a valuable strategy to enhance sensitivity towards hypoxia and may complement strategies targeting glucose metabolism.
Interaction of p53 with prolyl isomerases: Healthy and unhealthy relationships.

PubMed

Mantovani, Fiamma; Zannini, Alessandro; Rustighi, Alessandra; Del Sal, Giannino

2015-10-01

The p53 protein family, comprising p53, p63 and p73, is primarily involved in preserving genome integrity and preventing tumor onset, and also affects a range of physiological processes. Signal-dependent modifications of its members and of other pathway components provide cells with a sophisticated code to transduce a variety of stress signaling into appropriate responses. TP53 mutations are highly frequent in cancer and lead to the expression of mutant p53 proteins that are endowed with oncogenic activities and sensitive to stress signaling. p53 family proteins have unique structural and functional plasticity, and here we discuss the relevance of prolyl-isomerization to actively shape these features. The anti-proliferative functions of the p53 family are carefully activated upon severe stress and this involves the interaction with prolyl-isomerases. In particular, stress-induced stabilization of p53, activation of its transcriptional control over arrest- and cell death-related target genes and of its mitochondrial apoptotic function, as well as certain p63 and p73 functions, all require phosphorylation of specific S/T-P motifs and their subsequent isomerization by the prolyl-isomerase Pin1. While these functions of p53 counteract tumorigenesis, under some circumstances their activation by prolyl-isomerases may have negative repercussions (e.g. tissue damage induced by anticancer therapies and ischemia-reperfusion, neurodegeneration). Moreover, elevated Pin1 levels in tumor cells may transduce deregulated phosphorylation signaling into activation of mutant p53 oncogenic functions. The complex repertoire of biological outcomes induced by p53 finds mechanistic explanations, at least in part, in the association between prolyl-isomerases and the p53 pathway. This article is part of a Special Issue entitled Proline-directed foldases: Cell signaling catalysts and drug targets. Copyright © 2015 Elsevier B.V. All rights reserved.
Enhanced breast cancer progression by mutant p53 is inhibited by the circular RNA circ-Ccnb1.

PubMed

Fang, Ling; Du, William W; Lyu, Juanjuan; Dong, Jun; Zhang, Chao; Yang, Weining; He, Alina; Kwok, Yat Sze Sheila; Ma, Jian; Wu, Nan; Li, Feiya; Awan, Faryal Mehwish; He, Chengyan; Yang, Bing L; Peng, Chun; MacKay, Helen J; Yee, Albert J; Yang, Burton B

2018-05-23

TP53 mutations occur in many different types of cancers that produce mutant p53 proteins. The mutant p53 proteins have lost wild-type p53 activity and gained new functions that contribute to malignant tumor progression. Different p53 mutations create distinct profiles in loss of wild-type p53 activity and gain of functions. Targeting the consequences generated by the great number of p53 mutations would be extremely complex. Therefore, in this study we used a workaround and took advantage of the fact that mutant p53 cannot bind H2AX. Using this, we developed a new approach to repress the acquisition of mutant p53 functions. We show here that the delivery of a circular RNA circ-Ccnb1 inhibited the function of three p53 mutations. By microarray analysis and real-time PCR, we detected decreased circ-Ccnb1 expression levels in patients bearing breast carcinoma. Ectopic delivery of circ-Ccnb1 inhibited tumor growth and extended mouse viability. Using proteomics, we found that circ-Ccnb1 precipitated p53 in p53 wild-type cells, but instead precipitated Bclaf1 in p53 mutant cells. Further experiments showed that H2AX serves as a bridge, linking the interaction of circ-Ccnb1 and wild-type p53, thus allowing Bclaf1 to bind Bcl2 resulting in cell survival. In the p53 mutant cells, circ-Ccnb1 formed a complex with H2AX and Bclaf1, resulting in the induction of cell death. We found that this occurred in three p53 mutations. These results shed light on the possible development of new approaches to inhibit the malignancy of p53 mutations.
p53 as the focus of gene therapy: past, present and future.

PubMed

Valente, Joana Fa; Queiroz, Joao A; Sousa, Fani

2018-01-15

Several gene deviations can be responsible for triggering oncogenic processes. However, mutations in tumour suppressor genes are usually more associated to malignant diseases, being p53 one of the most affected and studied element. p53 is implicated in a number of known cellular functions, including DNA damage repair, cell cycle arrest in G1/S and G2/M and apoptosis, being an interesting target for cancer treatment. Considering these facts, the development of gene therapy approaches focused on p53 expression and regulation seems to be a promising strategy for cancer therapy. Several studies have shown that transfection of cancer cells with wild-type p53 expressing plasmids could directly drive cells into apoptosis and/or growth arrest, suggesting that a gene therapy approach for cancer treatment can be based on the re-establishment of the normal p53 expression levels and function. Up until now, several clinical research studies using viral and non-viral vectors delivering p53 genes, isolated or combined with other therapeutic agents, have been accomplished and there are already in the market therapies based on the use of this gene. This review summarizes the different methods used to deliver and/or target the p53 as well as the main results of therapeutic effect obtained with the different strategies applied. Finally, the ongoing approaches are described, also focusing the combinatorial therapeutics to show the increased therapeutic potential of combining gene therapy vectors with chemo or radiotherapy. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
Down-regulation of Wild-type p53-induced Phosphatase 1 (Wip1) Plays a Critical Role in Regulating Several p53-dependent Functions in Premature Senescent Tumor Cells*

PubMed Central

Crescenzi, Elvira; Raia, Zelinda; Pacifico, Francesco; Mellone, Stefano; Moscato, Fortunato; Palumbo, Giuseppe; Leonardi, Antonio

2013-01-01

Premature or drug-induced senescence is a major cellular response to chemotherapy in solid tumors. The senescent phenotype develops slowly and is associated with chronic DNA damage response. We found that expression of wild-type p53-induced phosphatase 1 (Wip1) is markedly down-regulated during persistent DNA damage and after drug release during the acquisition of the senescent phenotype in carcinoma cells. We demonstrate that down-regulation of Wip1 is required for maintenance of permanent G2 arrest. In fact, we show that forced expression of Wip1 in premature senescent tumor cells induces inappropriate re-initiation of mitosis, uncontrolled polyploid progression, and cell death by mitotic failure. Most of the effects of Wip1 may be attributed to its ability to dephosphorylate p53 at Ser15 and to inhibit DNA damage response. However, we also uncover a regulatory pathway whereby suppression of p53 Ser15 phosphorylation is associated with enhanced phosphorylation at Ser46, increased p53 protein levels, and induction of Noxa expression. On the whole, our data indicate that down-regulation of Wip1 expression during premature senescence plays a pivotal role in regulating several p53-dependent aspects of the senescent phenotype. PMID:23612976
Interleukin-6 increases matrix metalloproteinase-14 (MMP-14) levels via down-regulation of p53 to drive cancer progression

PubMed Central

Cathcart, Jillian M.; Banach, Anna; Liu, Alice; Chen, Jun; Goligorsky, Michael; Cao, Jian

2016-01-01

Matrix metalloproteinases (MMPs) play critical roles in cancer invasion and metastasis by digesting basement membrane and extracellular matrix (ECM). Much attention has focused on the enzymatic activities of MMPs; however, the regulatory mechanism of MMP expression remains elusive. By employing bioinformatics analysis, we identified a potential p53 response element within the MMP-14 promoter. Experimentally, we found that p53 can repress MMP-14 promoter activity, whereas deletion of this p53 response element abrogated this effect. Furthermore, we found that p53 expression decreases MMP-14 mRNA and protein levels and attenuates MMP-14-mediated cellular functions. Additional promoter analysis and chromatin immunoprecipitation studies identified a mechanism of regulation of MMP-14 expression by which p53 and transcription factor Sp1 competitively bind to the promoter. As the correlation between inflammation and cancer aggressiveness is well described, we next sought to evaluate if inflammatory cytokines could differentially affect p53 and MMP-14 levels. We demonstrate that interleukin-6 (IL-6) down-regulates p53 protein levels and thus results in a concomitant increase in MMP-14 expression, leading to enhanced cancer cell invasion and metastasis. Our data collectively indicate a novel mechanism of regulation of MMP-14 by a cascade of IL-6 and p53, demonstrating that the tumor microenvironment directly stimulates molecular changes in cancer cells to drive an invasive phenotype. PMID:27531896
Identification of two novel functional p53 responsive elements in the herpes simplex virus-1 genome.

PubMed

Hsieh, Jui-Cheng; Kuta, Ryan; Armour, Courtney R; Boehmer, Paul E

2014-07-01

Analysis of the herpes simplex virus-1 (HSV-1) genome reveals two candidate p53 responsive elements (p53RE), located in proximity to the replication origins oriL and oriS, referred to as p53RE-L and p53RE-S, respectively. The sequences of p53RE-L and p53RE-S conform to the p53 consensus site and are present in HSV-1 strains KOS, 17, and F. p53 binds to both elements in vitro and in virus-infected cells. Both p53RE-L and p53RE-S are capable of conferring p53-dependent transcriptional activation onto a heterologous reporter gene. Importantly, expression of the essential immediate early viral transactivator ICP4 and the essential DNA replication protein ICP8, that are adjacent to p53RE-S and p53RE-L, are repressed in a p53-dependent manner. Taken together, this study identifies two novel functional p53RE in the HSV-1 genome and suggests a complex mechanism of viral gene regulation by p53 which may determine progression of the lytic viral replication cycle or the establishment of latency. Copyright © 2014 Elsevier Inc. All rights reserved.
Targeting the p53 signaling pathway in cancer therapy - The promises, challenges, and perils

PubMed Central

Stegh, Alexander H.

2012-01-01

Introduction Research over the past three decades has identified p53 as a multifunctional transcription factor, which regulates the expression of >2,500 target genes. p53 impacts myriad, highly diverse cellular processes, including the maintenance of genomic stability and fidelity, metabolism, longevity, and represents one of the most important and extensively studied tumor suppressors. Activated by various stresses, foremost genotoxic damage, hypoxia, heat shock and oncogenic assault, p53 blocks cancer progression by provoking transient or permanent growth arrest, by enabling DNA repair or by advancing cellular death programs. This potent and versatile anti-cancer activity profile, together with genomic and mutational analyses documenting inactivation of p53 in more than 50% of human cancers, motivated drug development efforts to (re-) activate p53 in established tumors. Areas covered In this review the complexities of p53 signaling in cancer are summarized. Current strategies and challenges to restore p53’s tumor suppressive function in established tumors, i.e. adenoviral gene transfer and small molecules to activate p53, to inactivate p53 inhibitors and to restore wild type function of p53 mutant proteins are discussed. Expert opinion It is indubitable that p53 represents an attractive target for the development of anti-cancer therapies. Whether p53 is ‘druggable’, however, remains an area of active research and discussion, as p53 has pro-survival functions and chronic p53 activation accelerates aging, which may compromise the long-term homeostasis of an organism. Thus, the complex biology and dual functions of p53 in cancer prevention and age-related cellular responses pose significant challenges on the development of p53-targeting cancer therapies. PMID:22239435
Myc, Aurora Kinase-A, and mutant p53R172H co-operate in a mouse model of metastatic skin carcinoma

PubMed Central

Torchia, Enrique C.; Caulin, Carlos; Acin, Sergio; Terzian, Tamara; Kubick, Bradley J.; Box, Neil F.; Roop, Dennis R.

2015-01-01

Clinical observations, as well as data obtained from the analysis of genetically engineered mouse models, firmly established the gain-of-function (GOF) properties of certain p53 mutations. However, little is known about the underlying mechanisms. We have used two independent microarray platforms to perform a comprehensive and global analysis of tumors arising in a model of metastatic skin cancer progression, which compares the consequences of a GOF p53R172H mutant vs. p53 deficiency. DNA profiling revealed a higher level of genomic instability in GOF vs. loss-of-function (LOF) p53 squamous cell carcinomas (SCCs). Moreover, GOF p53 SCCs showed preferential amplification of Myc with a corresponding increase in its expression and deregulation of Aurora Kinase-A. Fluorescent in situ hybridization confirmed amplification of Myc in primary GOF p53 SCCs and its retention in metastatic tumors. We also identified by RNA profiling distinct gene expression profiles in GOF p53 tumors, which included enriched integrin and Rho signaling, independent of tumor stage. Thus, the progression of GOF p53 papillomas to carcinoma was marked by the acquisition of epithelial to mesenchymal transition and metastatic signatures. In contrast, LOF p53 tumors showed enrichment of genes associated with cancer proliferation and chromosomal instability. Collectively, these observations suggest that genomic instability plays a prominent role in the early stages of GOF p53 tumor progression (i.e., papillomas), while it is implicated at a later stage in LOF p53 tumors (i.e., SCCs). This model will allow us to identify specific targets in mutant p53 SCCs, which may lead to the development of new therapeutic agents for the treatment of metastatic SCCs. PMID:21963848
Expressions of p53 and p21 in primary gastric lymphomas.

PubMed Central

Go, J. H.; Yang, W. I.

2001-01-01

The p21 overexpression is thought to be a consequence of the p53 induced activation of the p21 gene. The immunohistochemical evaluation of p53 and p21 can be a valuable means of assessing the functional status of the p53 gene product. We examined the overexpression of p21 and p53 proteins in primary gastric lymphomas and the correlation with prognosis. A total of 32 cases of gastric lymphomas was classified into low-grade lymphomas of mucosa-associated lymphoid tissue type (n=16) and high-grade B-cell lymphomas (n=16). In low-grade lymphomas, only one case showed p53 positivity and all cases were p21-negative. In high-grade lymphomas, seven cases were p53+/p21- (44%), one case was p53+/p21+ (6%), and eight cases were p53-/p21- (50%). The p53+/p21- cases had a much lower percentage of patients sustaining a continuous complete remission state (3/7, 43%) compared with other cases (6/7, 86%). From these results, we concluded that p21 expression is rare in primary gastric lymphomas. Therefore, p53-positive lymphomas can be assumed as having p53 mutation. And combined studies of p53 and p21 may be used as a prognostic indicator in primary gastric high-grade lymphomas. PMID:11748353

Zn(II)-curc targets p53 in thyroid cancer cells.

PubMed

Garufi, Alessia; D'Orazi, Valerio; Crispini, Alessandra; D'Orazi, Gabriella

2015-10-01

TP53 mutation is a common event in many cancers, including thyroid carcinoma. Defective p53 activity promotes cancer resistance to therapies and a more malignant phenotype, acquiring oncogenic functions. Rescuing the function of mutant p53 (mutp53) protein is an attractive anticancer therapeutic strategy. Zn(II)-curc is a novel small molecule that has been shown to target mutp53 protein in several cancer cells, but its effect in thyroid cancer cells remains unclear. Here, we investigated whether Zn(II)-curc could affect p53 in thyroid cancer cells with both p53 mutation (R273H) and wild-type p53. Zn(II)-curc induced mutp53H273 downregulation and reactivation of wild-type functions, such as binding to canonical target promoters and target gene transactivation. This latter effect was similar to that induced by PRIMA-1. In addition, Zn(II)-curc triggered p53 target gene expression in wild-type p53-carrying cells. In combination treatments, Zn(II)-curc enhanced the antitumor activity of chemotherapeutic drugs, in both mutant and wild-type-carrying cancer cells. Taken together, our data indicate that Zn(II)-curc promotes the reactivation of p53 in thyroid cancer cells, providing in vitro evidence for a potential therapeutic approach in thyroid cancers.
Heterogeneous distribution of P53 immunoreactivity in human lung adenocarcinoma correlates with MDM2 protein expression, rather than with P53 gene mutation.

PubMed

Koga, T; Hashimoto, S; Sugio, K; Yoshino, I; Nakagawa, K; Yonemitsu, Y; Sugimachi, K; Sueishi, K

2001-07-20

Although the tumor suppressor p53 protein (P53) immunoreactivity and its gene (p53) mutation were reported to be significant prognostic indicators for human lung adenocarcinomas, little is known regarding the relationship between the heterogeneous distribution of P53 and its genetic status in each tumor focus and the clinicopathological significance. To determine how P53 is heterogeneously stabilized in patients, we compared P53 expression to both the p53 allelic mutation in exon 2 approximately 9 by polymerase chain reaction-single strand conformation polymorphism using microdissected DNA fractions, and the immunohistochemical MDM2 expression. Of the 48 positive to P53 in 118 lung adenocarcinomas examined, 10 with heterogeneous P53 expression were closely examined. The higher P53 expression foci in 7 of 10 cases were less differentiated, histologically in respective cases, and were frequently associated with fibrous stroma. Two had genetic mutations in exon 7 of the p53 gene in both the high and low P53 expression foci of cancer tissue indicating no apparent correlation between heterogeneous P53 expression and the occurrence of gene mutation. Immunohistochemical expression of MDM2 was significantly lower in high P53 expression areas (p < 0.05, the mean labeling indices of high and low P53 expression areas being 4.2 +/- 5.4% and 13.6 +/- 12.2%, respectively). In addition, among all the 118 cases examined, MDM2 expression was significantly suppressed in cases of p53 gene mutation, simultaneously with P53 overexpression, as compared with cases without both the p53 mutation and expression (p < 0.001). These findings suggest that the heterogeneous stabilization of P53 in human lung adenocarcinomas could be partly due to suppressed MDM2 expression. The overexpression of non-mutated P53 may afford a protective mechanism in human lung adenocarcinomas. Copyright 2001 Wiley-Liss, Inc.
Constant p53 Pathway Inactivation in a Large Series of Soft Tissue Sarcomas with Complex Genetics

PubMed Central

Pérot, Gaëlle; Chibon, Frédéric; Montero, Audrey; Lagarde, Pauline; de Thé, Hugues; Terrier, Philippe; Guillou, Louis; Ranchère, Dominique; Coindre, Jean-Michel; Aurias, Alain

2010-01-01

Alterations of the p53 pathway are among the most frequent aberrations observed in human cancers. We have performed an exhaustive analysis of TP53, p14, p15, and p16 status in a large series of 143 soft tissue sarcomas, rare tumors accounting for around 1% of all adult cancers, with complex genetics. For this purpose, we performed genomic studies, combining sequencing, copy number assessment, and expression analyses. TP53 mutations and deletions are more frequent in leiomyosarcomas than in undifferentiated pleomorphic sarcomas. Moreover, 50% of leiomyosarcomas present TP53 biallelic inactivation, whereas most undifferentiated pleomorphic sarcomas retain one wild-type TP53 allele (87.2%). The spectrum of mutations between these two groups of sarcomas is different, particularly with a higher rate of complex mutations in undifferentiated pleomorphic sarcomas. Most tumors without TP53 alteration exhibit a deletion of p14 and/or lack of mRNA expression, suggesting that p14 loss could be an alternative genotype for direct TP53 inactivation. Nevertheless, the fact that even in tumors altered for TP53, we could not detect p14 protein suggests that other p14 functions, independent of p53, could be implicated in sarcoma oncogenesis. In addition, both p15 and p16 are frequently codeleted or transcriptionally co-inhibited with p14, essentially in tumors with two wild-type TP53 alleles. Conversely, in TP53-altered tumors, p15 and p16 are well expressed, a feature not incompatible with an oncogenic process. PMID:20884963
Rapid colorimetric detection of p53 protein function using DNA-gold nanoconjugates with applications for drug discovery and cancer diagnostics.

PubMed

Assah, Enock; Goh, Walter; Zheng, Xin Ting; Lim, Ting Xiang; Li, Jun; Lane, David; Ghadessy, Farid; Tan, Yen Nee

2018-05-05

The tumor suppressor protein p53 plays a central role in preventing cancer through interaction with DNA response elements (REs) to regulate target gene expression in cells. Due to its significance in cancer biology, relentless efforts have been directed toward understanding p53-DNA interactions for the development of cancer therapeutics and diagnostics. In this paper, we report a rapid, label-free and versatile colorimetric assay to detect wildtype p53 DNA-binding function in complex solutions. The assay design is based on a concept that alters interparticle-distances between RE-AuNPs from a crosslinking effect induced through tetramerization of wildtype p53 protein (p53-WT) upon binding to canonical DNA motifs modified on gold nanoparticles (RE-AuNPs). This leads to a visible solution color change from red to blue, which is quantifiable by the UV- visible absorption spectra with a detection limit of 5 nM. Contrastingly, no color change was observed for the binding-deficient p53 mutants and non-specific proteins due to their inability to crosslink RE-AuNPs. Based on this sensing principle, we further demonstrate its utility for fast detection of drug-induced DNA binding function to cancer-associated Y220C mutant p53 protein using well-established reactivating compounds. By exploiting the dominant-negative property of mutant p53 over p53-WT and interactions with RE-AuNPs, this assay is configurable to detect low numbers of mutant p53 expressing cells in miniscule sample fractions obtained from typical core needle biopsy-sized tissues without signal attrition, alluding to the potential for biopsy sampling in cancer diagnostics or for defining cancer margins. This nanogold enabled colorimetric assay provides a facile yet robust method for studying important parameters influencing p53-DNA interactions with great promises for clinically pertinent applications. Copyright © 2018 Elsevier B.V. All rights reserved.
p73 coordinates with Δ133p53 to promote DNA double-strand break repair.

PubMed

Gong, Hongjian; Zhang, Yuxi; Jiang, Kunpeng; Ye, Shengfan; Chen, Shuming; Zhang, Qinghe; Peng, Jinrong; Chen, Jun

2018-03-06

Tumour repressor p53 isoform Δ133p53 is a target gene of p53 and an antagonist of p53-mediated apoptotic activity. We recently demonstrated that Δ133p53 promotes DNA double-strand break (DSB) repair by upregulating transcription of the repair genes RAD51, LIG4 and RAD52 in a p53-independent manner. However, Δ133p53 lacks the transactivation domain of full-length p53, and the mechanism by which it exerts transcriptional activity independently of full-length p53 remains unclear. In this report, we describe the accumulation of high levels of both Δ133p53 and p73 (a p53 family member) at 24 h post γ-irradiation (hpi). Δ133p53 can form a complex with p73 upon γ-irradiation. The co-expression of Δ133p53 and p73, but not either protein alone, can significantly promote DNA DSB repair mechanisms, including homologous recombination (HR), non-homologous end joining (NHEJ) and single-strand annealing (SSA). p73 and Δ133p53 act synergistically to promote the expression of RAD51, LIG4 and RAD52 by joining together to bind to region containing a Δ133p53-responsive element (RE) and a p73-RE in the promoters of all three repair genes. In addition to its accumulation at 24 hpi, p73 protein expression also peaks at 4 hpi. The depletion of p73 not only reduces early-stage apoptotic frequency (4-6 hpi), but also significantly increases later-stage DNA DSB accumulation (48 hpi), leading to cell cycle arrest in the G2 phase and, ultimately, cell senescence. In summary, the apoptotic regulator p73 also coordinates with Δ133p53 to promote DNA DSB repair, and the loss of function of p73 in DNA DSB repair may underlie spontaneous and carcinogen-induced tumorigenesis in p73 knockout mice.
Suppression of miR-34a Expression in the Myocardium Protects Against Ischemia-Reperfusion Injury Through SIRT1 Protective Pathway.

PubMed

Fu, Bi-Cheng; Lang, Ji-Lu; Zhang, Dong-Yang; Sun, Lu; Chen, Wei; Liu, Wei; Liu, Kai-Yu; Ma, Chong-Yi; Jiang, Shu-Lin; Li, Ren-Ke; Tian, Hai

2017-09-01

MicroRNA-34a (miR-34a) is expressed in the myocardium and expression is altered after myocardial injury. We investigated the effects of miR-34a on heart function after ischemia-reperfusion (IR) injury. Cardiomyocytes were isolated from neonatal rat hearts and simulated IR injury was induced in vitro. Following IR injury in rats, infarct size was measured and left ventricular (LV) function was evaluated using echocardiography. Protein expression of silent information regulator 1 (SIRT1), acetylated p53 (ac-p53), Bcl-2 and Bax, and miR-34a and SIRT1 gene levels were analyzed. miR-34a overexpression exacerbated myocardial injury by increasing apoptosis and infarct size and decreasing LV function. Suppression of miR-34a attenuated myocardial IR injury. SIRT1 was negatively regulated by miR-34a and the expression of downstream genes, such as ac-p53, Bcl-2, and Bax were altered correspondingly. Increased expression of miR-34a aggravates injury after IR; miR-34a suppression therapy may represent a new line of treatment for myocardial IR injury.
p53-independent p21 induction by MELK inhibition.

PubMed

Matsuda, Tatsuo; Kato, Taigo; Kiyotani, Kazuma; Tarhan, Yunus Emre; Saloura, Vassiliki; Chung, Suyoun; Ueda, Koji; Nakamura, Yusuke; Park, Jae-Hyun

2017-08-29

MELK play critical roles in human carcinogenesis through activation of cell proliferation, inhibition of apoptosis and maintenance of stemness. Therefore, MELK is a promising therapeutic target for a wide range of cancers. Although p21 is a well-known p53-downstream gene, we found that treatment with a potent MELK inhibitor, OTS167, could induce p21 protein expression in cancer cell lines harboring loss-of-function TP53 mutations. We also confirmed that MELK knockdown by siRNA induced the p21 expression in p53-deficient cancer cell lines and caused the cell cycle arrest at G1 phase. Further analysis indicated that FOXO1 and FOXO3, two known transcriptional regulators of p21, were phosphorylated by MELK and thus be involved in the induction of p21 after MELK inhibition. Collectively, our herein findings suggest that MELK inhibition may be effective for human cancers even if TP53 is mutated.
p53-independent p21 induction by MELK inhibition

PubMed Central

Matsuda, Tatsuo; Kato, Taigo; Kiyotani, Kazuma; Tarhan, Yunus Emre; Saloura, Vassiliki; Chung, Suyoun; Ueda, Koji; Nakamura, Yusuke; Park, Jae-Hyun

2017-01-01

MELK play critical roles in human carcinogenesis through activation of cell proliferation, inhibition of apoptosis and maintenance of stemness. Therefore, MELK is a promising therapeutic target for a wide range of cancers. Although p21 is a well-known p53-downstream gene, we found that treatment with a potent MELK inhibitor, OTS167, could induce p21 protein expression in cancer cell lines harboring loss-of-function TP53 mutations. We also confirmed that MELK knockdown by siRNA induced the p21 expression in p53-deficient cancer cell lines and caused the cell cycle arrest at G1 phase. Further analysis indicated that FOXO1 and FOXO3, two known transcriptional regulators of p21, were phosphorylated by MELK and thus be involved in the induction of p21 after MELK inhibition. Collectively, our herein findings suggest that MELK inhibition may be effective for human cancers even if TP53 is mutated. PMID:28938528
Activation of EVI1 transcription by the LEF1/β-catenin complex with p53-alteration in myeloid blast crisis of chronic myeloid leukemia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manachai, Nawin; Saito, Yusuke; Nakahata, Shingo

The presence of a BCR-ABL1 fusion gene is necessary for the pathogenesis of chronic myeloid leukemia (CML) through t(9;22)(q34;q11) translocation. Imatinib, an ABL tyrosine kinase inhibitor, is dramatically effective in CML patients; however, 30% of CML patients will need further treatment due to progression of CML to blast crisis (BC). Aberrant high expression of ecotropic viral integration site 1 (EVI1) is frequently observed in CML during myeloid-BC as a potent driver with a CML stem cell signature; however, the precise molecular mechanism of EVI1 transcriptional regulation during CML progression is poorly defined. Here, we demonstrate the transcriptional activity of EVI1more » is dependent on activation of lymphoid enhancer-binding factor 1 (LEF1)/β-catenin complex by BCR-ABL with loss of p53 function during CML-BC. The activation of β-catenin is partly dependent on BCR-ABL expression through enhanced GSK3β phosphorylation, and EVI1 expression is directly enhanced by the LEF1/β-catenin complex bound to the EVI1 promoter region. Moreover, the loss of p53 expression is inversely correlated with high expression of EVI1 in CML leukemia cells with an aggressive phase of CML, and a portion of the activation mechanism of EVI1 expression is dependent on β-catenin activation through GSK3β phosphorylation by loss of p53. Therefore, we found that the EVI1 activation in CML-BC is dependent on LEF1/β-catenin activation by BCR-ABL expression with loss of p53 function, representing a novel selective therapeutic approach targeting myeloid blast crisis progression. - Highlights: • Transcriptional regulation of EVI1 in CML-BC is proposed. • EVI1 transcription is directly regulated by LEF1/β-catenin complex in CML-BC. • Loss of p53 function as a key regulator for β-catenin-EVI1 in CML myeloid-BC. • The LEF1/β-catenin binding site on the EVI1 promoter is a new target for CML-BC.« less
MicroRNA-125b is a novel negative regulator of p53.

PubMed

Le, Minh T N; Teh, Cathleen; Shyh-Chang, Ng; Xie, Huangming; Zhou, Beiyan; Korzh, Vladimir; Lodish, Harvey F; Lim, Bing

2009-04-01

The p53 transcription factor is a key tumor suppressor and a central regulator of the stress response. To ensure a robust and precise response to cellular signals, p53 gene expression must be tightly regulated from the transcriptional to the post-translational levels. Computational predictions suggest that several microRNAs are involved in the post-transcriptional regulation of p53. Here we demonstrate that miR-125b, a brain-enriched microRNA, is a bona fide negative regulator of p53 in both zebrafish and humans. miR-125b-mediated down-regulation of p53 is strictly dependent on the binding of miR-125b to a microRNA response element in the 3' untranslated region of p53 mRNA. Overexpression of miR-125b represses the endogenous level of p53 protein and suppresses apoptosis in human neuroblastoma cells and human lung fibroblast cells. In contrast, knockdown of miR-125b elevates the level of p53 protein and induces apoptosis in human lung fibroblasts and in the zebrafish brain. This phenotype can be rescued significantly by either an ablation of endogenous p53 function or ectopic expression of miR-125b in zebrafish. Interestingly, miR-125b is down-regulated when zebrafish embryos are treated with gamma-irradiation or camptothecin, corresponding to the rapid increase in p53 protein in response to DNA damage. Ectopic expression of miR-125b suppresses the increase of p53 and stress-induced apoptosis. Together, our study demonstrates that miR-125b is an important negative regulator of p53 and p53-induced apoptosis during development and during the stress response.
MicroRNA-125b is a novel negative regulator of p53

PubMed Central

Le, Minh T.N.; Teh, Cathleen; Shyh-Chang, Ng; Xie, Huangming; Zhou, Beiyan; Korzh, Vladimir; Lodish, Harvey F.; Lim, Bing

2009-01-01

The p53 transcription factor is a key tumor suppressor and a central regulator of the stress response. To ensure a robust and precise response to cellular signals, p53 gene expression must be tightly regulated from the transcriptional to the post-translational levels. Computational predictions suggest that several microRNAs are involved in the post-transcriptional regulation of p53. Here we demonstrate that miR-125b, a brain-enriched microRNA, is a bona fide negative regulator of p53 in both zebrafish and humans. miR-125b-mediated down-regulation of p53 is strictly dependent on the binding of miR-125b to a microRNA response element in the 3′ untranslated region of p53 mRNA. Overexpression of miR-125b represses the endogenous level of p53 protein and suppresses apoptosis in human neuroblastoma cells and human lung fibroblast cells. In contrast, knockdown of miR-125b elevates the level of p53 protein and induces apoptosis in human lung fibroblasts and in the zebrafish brain. This phenotype can be rescued significantly by either an ablation of endogenous p53 function or ectopic expression of miR-125b in zebrafish. Interestingly, miR-125b is down-regulated when zebrafish embryos are treated with γ-irradiation or camptothecin, corresponding to the rapid increase in p53 protein in response to DNA damage. Ectopic expression of miR-125b suppresses the increase of p53 and stress-induced apoptosis. Together, our study demonstrates that miR-125b is an important negative regulator of p53 and p53-induced apoptosis during development and during the stress response. PMID:19293287
p53 targets chromatin structure alteration to repress alpha-fetoprotein gene expression.

PubMed

Ogden, S K; Lee, K C; Wernke-Dollries, K; Stratton, S A; Aronow, B; Barton, M C

2001-11-09

Many of the functions ascribed to p53 tumor suppressor protein are mediated through transcription regulation. We have shown that p53 represses hepatic-specific alpha-fetoprotein (AFP) gene expression by direct interaction with a composite HNF-3/p53 DNA binding element. Using solid-phase, chromatin-assembled AFP DNA templates and analysis of chromatin structure and transcription in vitro, we find that p53 binds DNA and alters chromatin structure at the AFP core promoter to regulate transcription. Chromatin assembled in the presence of hepatoma extracts is activated for AFP transcription with an open, accessible core promoter structure. Distal (-850) binding of p53 during chromatin assembly, but not post-assembly, reverses transcription activation concomitant with promoter inaccessibility to restriction enzyme digestion. Inhibition of histone deacetylase activity by trichostatin-A (TSA) addition, prior to and during chromatin assembly, activated chromatin transcription in parallel with increased core promoter accessibility. Chromatin immunoprecipitation analyses showed increased H3 and H4 acetylated histones at the core promoter in the presence of TSA, while histone acetylation remained unchanged at the site of distal p53 binding. Our data reveal that p53 targets chromatin structure alteration at the core promoter, independently of effects on histone acetylation, to establish repressed AFP gene expression.
Improving survival by exploiting tumor dependence on stabilized mutant p53 for treatment

PubMed Central

Alexandrova, EM; Yallowitz, AR; Li, D; Xu, S; Schulz, R; Proia, DA; Lozano, G; Dobbelstein, M; Moll, UM

2015-01-01

SUMMARY Missense mutations in p53 generate aberrant proteins with abrogated tumor suppressor functions that can also acquire oncogenic gain-of-functions (GOF) that promote malignant progression, invasion, metastasis and chemoresistance1–5. Mutant p53 (mutp53) proteins undergo massive constitutive stabilization specifically in tumors, which is the key requisite for GOF6–8. Although currently 11 million patients worldwide live with tumors expressing highly stabilized mutp53, it is unknown whether mutp53 is a therapeutic target in vivo. Here we use a novel mutp53 mouse model expressing an inactivatible R248Q hotspot mutation (floxQ) to show that tumors depend on sustained mutp53 expression. Upon Tamoxifen-induced mutp53 ablation, allo-transplanted and autochthonous tumors curb their growth, thus extending animal survival by 37%, and advanced tumors undergo apoptosis and tumor regression or stagnation. The HSP90/HDAC6 chaperone machinery, which is significantly upregulated in cancer compared to normal tissues, is a major determinant of mutp53 stabilization9–12. We show that long-term HSP90 inhibition significantly extends the survival of mutp53 Q/−2 and H/H (R172H allele3) mice by 59% and 48%, respectively, but not their respective p53−/− littermates. This mutp53-dependent drug effect occurs in H/H mice treated with 17DMAG+SAHA and in H/H and Q/− mice treated with the potent Hsp90 inhibitor ganetespib. Notably, drug activity correlates with induction of mutp53 degradation, tumor apoptosis and prevention of T-lymphomagenesis. These proof-of-principle data identify mutp53 as an actionable cancer-specific drug target. PMID:26009011
Prognostic impact of c-Rel nuclear expression and REL amplification and crosstalk between c-Rel and the p53 pathway in diffuse large B-cell lymphoma

PubMed Central

Ok, Chi Young; Tzankov, Alexandar; Manyam, Ganiraju C.; Sun, Ruifan; Visco, Carlo; Zhang, Mingzhi; Montes-Moreno, Santiago; Dybkaer, Karen; Chiu, April; Orazi, Attilio; Zu, Youli; Bhagat, Govind; Richards, Kristy L.; Hsi, Eric D.; Choi, William W.L.; van Krieken, J. Han; Huh, Jooryung; Ponzoni, Maurilio; Ferreri, Andrés J.M.; Møller, Michael B.; Wang, Jinfeng; Parsons, Ben M.; Winter, Jane N.; Piris, Miguel A.; Pham, Lan V.; Medeiros, L. Jeffrey; Young, Ken H.

2015-01-01

Dysregulated NF-κB signaling is critical for lymphomagenesis. The regulation, function, and clinical relevance of c-Rel/NF-κB activation in diffuse large B-cell lymphoma (DLBCL) have not been well studied. In this study we analyzed the prognostic significance and gene-expression signature of c-Rel nuclear expression as surrogate of c-Rel activation in 460 patients with de novo DLBCL. Nuclear c-Rel expression, observed in 137 (26.3%) DLBCL patients frequently associated with extranoal origin, did not show significantly prognostic impact in the overall- or germinal center B-like-DLBCL cohort, likely due to decreased pAKT and Myc levels, up-regulation of FOXP3, FOXO3, MEG3 and other tumor suppressors coincided with c-Rel nuclear expression, as well as the complicated relationships between NF-κB members and their overlapping function. However, c-Rel nuclear expression correlated with significantly poorer survival in p63+ and BCL-2− activated B-cell-like-DLBCL, and in DLBCL patients with TP53 mutations. Multivariate analysis indicated that after adjusting clinical parameters, c-Rel positivity was a significantly adverse prognostic factor in DLBCL patients with wild type TP53. Gene expression profiling suggested dysregulations of cell cycle, metabolism, adhesion, and migration associated with c-Rel activation. In contrast, REL amplification did not correlate with c-Rel nuclear expression and patient survival, likely due to co-amplification of genes that negatively regulate NF-κB activation. These insights into the expression, prognostic impact, regulation and function of c-Rel as well as its crosstalk with the p53 pathway underscore the importance of c-Rel and have significant therapeutic implications. PMID:26324762
BTK blocks the inhibitory effects of MDM2 on p53 activity

PubMed Central

Rada, Miran; Althubiti, Mohammad; Ekpenyong-Akiba, Akang E.; Lee, Koon-Guan; Lam, Kong Peng; Fedorova, Olga; Barlev, Nickolai A.; Macip, Salvador

2017-01-01

p53 is a tumour suppressor that is activated in response to various types of stress. It is regulated by a complex pattern of over 50 different post-translational modifications, including ubiquitination by the E3 ligase MDM2, which leads to its proteasomal degradation. We have previously reported that expression of Bruton’s Tyrosine Kinase (BTK) induces phosphorylation of p53 at the N-terminus, including Serine 15, and increases its protein levels and activity. The mechanisms involved in this process are not completely understood. Here, we show that BTK also increases MDM2 and is necessary for MDM2 upregulation after DNA damage, consistent with what we have shown for other p53 target genes. Moreover, we found that BTK binds to MDM2 on its PH domain and induces its phosphorylation. This suggested a negative regulation of MDM2 functions by BTK, supported by the fact BTK expression rescued the inhibitory effects of MDM2 on p53 transcriptional activity. Indeed, we observed that BTK mediated the loss of the ubiquitination activity of MDM2, a process that was dependent on the phosphorylation functions of BTK. Our data together shows that the kinase activity of BTK plays an important role in disrupting the MDM2-p53 negative feedback loop by acting at different levels, including binding to and inactivation of MDM2. This study provides a potential mechanism to explain how BTK modulates p53 functions. PMID:29290977
Induction of MDM2-P2 Transcripts Correlates with Stabilized Wild-Type p53 in Betel- and Tobacco-Related Human Oral Cancer

PubMed Central

Ralhan, Ranju; Sandhya, Agarwal; Meera, Mathur; Bohdan, Wasylyk; Nootan, Shukla K.

2000-01-01

MDM2, a critical element of cellular homeostasis mechanisms, is involved in complex interactions with important cell-cycle and stress-response regulators including p53. The mdm2-P2 promoter is a transcriptional target of p53. The aim of this study was to determine the association between mdm2-P2 transcripts and the status of the p53 gene in betel- and tobacco-related oral squamous cell carcinomas (SCCs) to understand the mechanism of deregulation of MDM2 and p53 expression and their prognostic implications in oral tumorigenesis. Elevated levels of MDM2 proteins were observed in 11 of 25 (44%) oral hyperplastic lesions, nine of 15 (60%) dysplastic lesions, and 71 of 100 (71%) SCCs. The intriguing feature of the study was the identification and different subcellular localization of three isoforms of MDM2 (ie, 90 kd, 76 kd, and 57 kd) in oral SCCs and their correlation with p53 overexpression in each tumor. The hallmark of the study was the detection of mdm2-P2 transcripts in 12 of 20 oral SCCs overexpressing both MDM2 and p53 proteins while harboring wild-type p53 alleles. Furthermore, mdm2 amplification was an infrequent event in betel- and tobacco-associated oral tumorigenesis. The differential compartmentalization of the three isoforms of MDM2 suggests that each has a distinct function, potentially in the regulation of p53 and other gene products implicated in oral tumorigenesis. In conclusion, we report herein the first evidence suggesting that enhanced translation of mdm2-P2 transcripts (S-mdm2) may represent an important mechanism of overexpression and consequent stabilization and functional inactivation of wild-type p53 serving as an adverse prognosticator in betel- and tobacco-related oral cancer. The clinical significance of the functional inactivation of wild-type p53 by MDM2 is underscored by the significantly shorter median disease-free survival time (16 months) observed in p53/MDM2-positive cases as compared to those which did not show co-expression of these proteins (median time, 26 months; P = 0.02). PMID:10934161
Mutant p53 establishes targetable tumor dependency by promoting unscheduled replication

PubMed Central

Singh, Shilpa; Vaughan, Catherine A.; Frum, Rebecca A.; Grossman, Steven R.; Deb, Sumitra

2017-01-01

Gain-of-function (GOF) p53 mutations are observed frequently in most intractable human cancers and establish dependency for tumor maintenance and progression. While some of the genes induced by GOF p53 have been implicated in more rapid cell proliferation compared with p53-null cancer cells, the mechanism for dependency of tumor growth on mutant p53 is unknown. This report reveals a therapeutically targetable mechanism for GOF p53 dependency. We have shown that GOF p53 increases DNA replication origin firing, stabilizes replication forks, and promotes micronuclei formation, thus facilitating the proliferation of cells with genomic abnormalities. In contrast, absence or depletion of GOF p53 leads to decreased origin firing and a higher frequency of fork collapse in isogenic cells, explaining their poorer proliferation rate. Following genome-wide analyses utilizing ChIP-Seq and RNA-Seq, GOF p53–induced origin firing, micronuclei formation, and fork protection were traced to the ability of GOF p53 to transactivate cyclin A and CHK1. Highlighting the therapeutic potential of CHK1’s role in GOF p53 dependency, experiments in cell culture and mouse xenografts demonstrated that inhibition of CHK1 selectively blocked proliferation of cells and tumors expressing GOF p53. Our data suggest the possibility that checkpoint inhibitors could efficiently and selectively target cancers expressing GOF p53 alleles. PMID:28394262
A planarian p53 homolog regulates proliferation and self-renewal in adult stem cell lineages.

PubMed

Pearson, Bret J; Sánchez Alvarado, Alejandro

2010-01-01

The functions of adult stem cells and tumor suppressor genes are known to intersect. However, when and how tumor suppressors function in the lineages produced by adult stem cells is unknown. With a large population of stem cells that can be manipulated and studied in vivo, the freshwater planarian is an ideal system with which to investigate these questions. Here, we focus on the tumor suppressor p53, homologs of which have no known role in stem cell biology in any invertebrate examined thus far. Planaria have a single p53 family member, Smed-p53, which is predominantly expressed in newly made stem cell progeny. When Smed-p53 is targeted by RNAi, the stem cell population increases at the expense of progeny, resulting in hyper-proliferation. However, ultimately the stem cell population fails to self-renew. Our results suggest that prior to the vertebrates, an ancestral p53-like molecule already had functions in stem cell proliferation control and self-renewal.
Murine Gammaherpesvirus 68 LANA and SOX Homologs Counteract ATM-Driven p53 Activity during Lytic Viral Replication

PubMed Central

Sifford, Jeffrey M.; Stahl, James A.; Salinas, Eduardo

2015-01-01

ABSTRACT Tumor suppressor p53 is activated in response to numerous cellular stresses, including viral infection. However, whether murine gammaherpesvirus 68 (MHV68) provokes p53 during the lytic replication cycle has not been extensively evaluated. Here, we demonstrate that MHV68 lytic infection induces p53 phosphorylation and stabilization in a manner that is dependent on the DNA damage response (DDR) kinase ataxia telangiectasia mutated (ATM). The induction of p53 during MHV68 infection occurred in multiple cell types, including splenocytes of infected mice. ATM and p53 activation required early viral gene expression but occurred independently of viral DNA replication. At early time points during infection, p53-responsive cellular genes were induced, coinciding with p53 stabilization and phosphorylation. However, p53-related gene expression subsided as infection progressed, even though p53 remained stable and phosphorylated. Infected cells also failed to initiate p53-dependent gene expression and undergo apoptosis in response to treatment with exogenous p53 agonists. The inhibition of p53 responses during infection required the expression of the MHV68 homologs of the shutoff and exonuclease protein (muSOX) and latency-associated nuclear antigen (mLANA). Interestingly, mLANA, but not muSOX, was necessary to prevent p53-mediated death in MHV68-infected cells under the conditions tested. This suggests that muSOX and mLANA are differentially required for inhibiting p53 in specific settings. These data reveal that DDR responses triggered by MHV68 infection promote p53 activation. However, MHV68 encodes at least two proteins capable of limiting the potential consequences of p53 function. IMPORTANCE Gammaherpesviruses are oncogenic herpesviruses that establish lifelong chronic infections. Defining how gammaherpesviruses overcome host responses to infection is important for understanding how these viruses infect and cause disease. Here, we establish that murine gammaherpesvirus 68 induces the activation of tumor suppressor p53. p53 activation was dependent on the DNA damage response kinase ataxia telangiectasia mutated. Although active early after infection, p53 became dominantly inhibited as the infection cycle progressed. Viral inhibition of p53 was mediated by the murine gammaherpesvirus 68 homologs of muSOX and mLANA. The inhibition of the p53 pathway enabled infected cells to evade p53-mediated cell death responses. These data demonstrate that a gammaherpesvirus encodes multiple proteins to limit p53-mediated responses to productive viral infection, which likely benefits acute viral replication and the establishment of chronic infection. PMID:26676792
Activation of EVI1 transcription by the LEF1/β-catenin complex with p53-alteration in myeloid blast crisis of chronic myeloid leukemia.

PubMed

Manachai, Nawin; Saito, Yusuke; Nakahata, Shingo; Bahirvani, Avinash Govind; Osato, Motomi; Morishita, Kazuhiro

2017-01-22

The presence of a BCR-ABL1 fusion gene is necessary for the pathogenesis of chronic myeloid leukemia (CML) through t(9;22)(q34;q11) translocation. Imatinib, an ABL tyrosine kinase inhibitor, is dramatically effective in CML patients; however, 30% of CML patients will need further treatment due to progression of CML to blast crisis (BC). Aberrant high expression of ecotropic viral integration site 1 (EVI1) is frequently observed in CML during myeloid-BC as a potent driver with a CML stem cell signature; however, the precise molecular mechanism of EVI1 transcriptional regulation during CML progression is poorly defined. Here, we demonstrate the transcriptional activity of EVI1 is dependent on activation of lymphoid enhancer-binding factor 1 (LEF1)/β-catenin complex by BCR-ABL with loss of p53 function during CML-BC. The activation of β-catenin is partly dependent on BCR-ABL expression through enhanced GSK3β phosphorylation, and EVI1 expression is directly enhanced by the LEF1/β-catenin complex bound to the EVI1 promoter region. Moreover, the loss of p53 expression is inversely correlated with high expression of EVI1 in CML leukemia cells with an aggressive phase of CML, and a portion of the activation mechanism of EVI1 expression is dependent on β-catenin activation through GSK3β phosphorylation by loss of p53. Therefore, we found that the EVI1 activation in CML-BC is dependent on LEF1/β-catenin activation by BCR-ABL expression with loss of p53 function, representing a novel selective therapeutic approach targeting myeloid blast crisis progression. Copyright © 2016 Elsevier Inc. All rights reserved.

Integration of Genomic, Biologic, and Chemical Approaches to Target p53 Loss and Gain-of-Function in Triple Negative Breast Cancer

DTIC Science & Technology

2016-09-01

in this progress report: p53 triple-negative breast cancer subtypes gene expression somatic cell genetics CRISPR /Cas 3. ACCOMPLISHMENTS Major...report, we described the creation of an isogenic p53 mutant TNBC cell line panel using CRISPR /Cas-mediated genome editing8 and the resultant...LOF null state. To validate that mutant p53 is directly responsible for this altered transcription, we will use the same CRISPR -mediated genome
Rescue of p53 function by small-molecule RITA in cervical carcinoma by blocking E6-mediated degradation.

PubMed

Zhao, Carolyn Ying; Szekely, Laszlo; Bao, Wenjie; Selivanova, Galina

2010-04-15

Proteasomal degradation of p53 by human papilloma virus (HPV) E6 oncoprotein plays a pivotal role in the survival of cervical carcinoma cells. Abrogation of HPV-E6-dependent p53 destruction can therefore be a good strategy to combat cervical carcinomas. Here, we show that a small-molecule reactivation of p53 and induction of tumor cell apoptosis (RITA) is able to induce the accumulation of p53 and rescue its tumor suppressor function in cells containing high-risk HPV16 and HPV18 by inhibiting HPV-E6-mediated proteasomal degradation. RITA blocks p53 ubiquitination by preventing p53 interaction with E6-associated protein, required for HPV-E6-mediated degradation. RITA activates the transcription of proapoptotic p53 targets Noxa, PUMA, and BAX, and repressed the expression of pro-proliferative factors CyclinB1, CDC2, and CDC25C, resulting in p53-dependent apoptosis and cell cycle arrest. Importantly, RITA showed substantial suppression of cervical carcinoma xenografts in vivo. These results provide a proof of principle for the treatment of cervical cancer in a p53-dependent manner by using small molecules that target p53. (c)2010 AACR.
MYCN acts as a direct co-regulator of p53 in MYCN amplified neuroblastoma.

PubMed

Agarwal, Saurabh; Milazzo, Giorgio; Rajapakshe, Kimal; Bernardi, Ronald; Chen, Zaowen; Barberi, Eveline; Koster, Jan; Perini, Giovanni; Coarfa, Cristian; Shohet, Jason M

2018-04-17

The MYC oncogenes and p53 have opposing yet interrelated roles in normal development and tumorigenesis. How MYCN expression alters the biology and clinical responsiveness of pediatric neuroblastoma remains poorly defined. Neuroblastoma is p53 wild type at diagnosis and repression of p53 signaling is required for tumorigenesis. Here, we tested the hypothesis that MYCN amplification alters p53 transcriptional activity in neuroblastoma. Interestingly, we found that MYCN directly binds to the tetrameric form of p53 at its C-terminal domain, and this interaction is independent of MYCN/MAX heterodimer formation. Chromatin analysis of MYCN and p53 targets reveals dramatic changes in binding, as well as co-localization of the MYCN-p53 complex at p53-REs and E-boxes of genes critical to DNA damage responses and cell cycle progression. RNA sequencing studies show that MYCN-p53 co-localization significantly modulated the expression of p53 target genes. Furthermore, MYCN-p53 interaction leads to regulation of alternative p53 targets not regulated in the presence of low MYCN levels. These novel targets include a number of genes involved in lipid metabolism, DNA repair, and apoptosis. Taken together, our findings demonstrate a novel oncogenic role of MYCN as a transcriptional co-regulator of p53 in high-risk MYCN amplified neuroblastoma. Targeting this novel oncogenic function of MYCN may enhance p53-mediated responses and sensitize MYCN amplified tumors to chemotherapy.
Loss of p53 promotes anaplasia and local invasion in ret/PTC1-induced thyroid carcinomas.

PubMed

La Perle, K M; Jhiang, S M; Capen, C C

2000-08-01

Papillary thyroid carcinomas in humans are associated with the ret/PTC oncogene and, following loss of p53 function, may progress to anaplastic carcinomas. Mice with thyroid-targeted expression of ret/PTC1 developed papillary thyroid carcinomas that were minimally invasive and did not metastasize. These mice were crossed with p53-/- mice to investigate whether loss of p53 would promote anaplasia and metastasis of ret/PTC1-induced thyroid tumors. The majority of p53-/- mice died or were euthanized by 17 weeks of age due to the development of thymic lymphomas, soft tissue sarcomas, and testicular teratomas. All ret/PTC1 mice developed thyroid carcinomas, but tumors in p53-/- mice were more anaplastic, larger in diameter, more invasive, and had a higher mitotic index than tumors in p53+/+ and p53+/- mice. Thyroid tumors did not metastasize in any of the experimental p53+/+ and p53+/- mice
Regulation of p53 expression and apoptosis by vault RNA2-1-5p in cervical cancer cells.

PubMed

Kong, Lu; Hao, Qi; Wang, Ying; Zhou, Ping; Zou, Binbin; Zhang, Yu-xiang

2015-09-29

nc886 or VRNA2-1 has recently been identified as a noncoding RNA instead of a vault RNA or a pre-microRNA. Several studies have reported that pre-miR-886 plays a tumor-suppressive role in a wide range of cancer cells through its activity as a cellular protein kinase RNA-activated (PKR) ligand and repressor. However, by sequencing stem-PCR products, we found that a microRNA originating from this precursor, vault RNA2-1-5p (VTRNA2-1-5p), occurs in cervical cancer cells. The expression levels of the predicted targets of VTRNA2-1-5p are negatively correlated with VTRNA2-1-5p levels by quantitative reversion transcription PCR (qRT-PCR). Previous results have shown that VTRNA2-1-5p is overexpressed in human cervical squamous cell carcinomas (CSCCs) compared with adjacent healthy tissues. Inhibition of VTRNA2-1-5p increases Bax protein expression and apoptotic cell death in cervical cancer cells. Our findings suggest that VTRNA2-1-5p has oncogenic activity related to the progression of cervical cancer. Here, we report that VTRNA2-1-5p directly targeted p53 expression and functioned as an oncomir in cervical cancer. VTRNA2-1-5p inhibition decreased cervical cancer cell invasion, proliferation, and tumorigenicity while increasing apoptosis and p53 expression. Interestingly, VTRNA2-1-5p inhibition also increased cisplatin-induced apoptosis of HeLa and SiHa cells. In human clinical cervical cancer specimens, low p53 expression and high VTRNA2-1-5p expression were positively associated.In addition, VTRNA2-1-5p was found to directly target the 5' and 3' untranslated regions (UTRs) of p53. We propose that VTRNA2-1-5p is a direct regulator of p53 and suggest that it plays an essential role in the apoptosis and proliferation of cervical cancer cells.
Transcriptional specificity in various p53-mutant cells.

PubMed

Okaichi, Kumio; Izumi, Nanaka; Takamura, Yuma; Fukui, Shoichi; Kudo, Takashi

2013-03-01

Mutation of the tumor suppressor gene p53 is the most common genetic alteration observed in human tumors. However, the relationship between the mutation point of p53 and the transcriptional specificity is not so obvious. We prepared Saos-2 cells with various mutations of p53 that are found in human tumors, and examined the resulting transcriptional alterations in the cells. Loss of function and gain of function were observed in all p53 mutants. Hot-spot mutations of p53 are frequently found in tumor cells. We compared hot-spot mutations and other mutations of p53 and found that a more than 2-fold transcription of CADPS2, PIWIL4 and TRIM9 was induced by hot spot mutations, but not by other mutations. As PIWIL4 suppresses the p16(INK4A) and ARF pathway, restraining cell growth and genomic instability, induction of PIWIL4 expression may be one reason why hot-spot mutations are frequently found in tumor cells.
The Prognostic Impact of p53 Expression on Sporadic Colorectal Cancer Is Dependent on p21 Status.

PubMed

Kruschewski, Martin; Mueller, Kathrin; Lipka, Sybille; Budczies, Jan; Noske, Aurelia; Buhr, Heinz Johannes; Elezkurtaj, Sefer

2011-03-11

The prognostic value of p53 and p21 expression in colorectal cancer is still under debate. We hypothesize that the prognostic impact of p53 expression is dependent on p21 status. The expression of p53 and p21 was immunohistochemically investigated in a prospective cohort of 116 patients with UICC stage II and III sporadic colorectal cancer. The results were correlated with overall and recurrence-free survival. The mean observation period was 51.8 ± 2.5 months. Expression of p53 was observed in 72 tumors (63%). Overall survival was significantly better in patients with p53-positive carcinomas than in those without p53 expression (p = 0.048). No differences were found in recurrence-free survival (p = 0.161). The p53+/p21- combination was seen in 68% (n = 49), the p53+/p21+ combination in 32% (n = 23). Patients with p53+/p21- carcinomas had significantly better overall and recurrence-free survival than those with p53+/p21+ (p < 0.0001 resp. p = 0.003). Our data suggest that the prognostic impact of p53 expression on sporadic colorectal cancer is dependent on p21 status.
Cytoplasmic destruction of p53 by the endoplasmic reticulum-resident ubiquitin ligase ‘Synoviolin'

PubMed Central

Yamasaki, Satoshi; Yagishita, Naoko; Sasaki, Takeshi; Nakazawa, Minako; Kato, Yukihiro; Yamadera, Tadayuki; Bae, Eunkyung; Toriyama, Sayumi; Ikeda, Rie; Zhang, Lei; Fujitani, Kazuko; Yoo, Eunkyung; Tsuchimochi, Kaneyuki; Ohta, Tomohiko; Araya, Natsumi; Fujita, Hidetoshi; Aratani, Satoko; Eguchi, Katsumi; Komiya, Setsuro; Maruyama, Ikuro; Higashi, Nobuyo; Sato, Mitsuru; Senoo, Haruki; Ochi, Takahiro; Yokoyama, Shigeyuki; Amano, Tetsuya; Kim, Jaeseob; Gay, Steffen; Fukamizu, Akiyoshi; Nishioka, Kusuki; Tanaka, Keiji; Nakajima, Toshihiro

2007-01-01

Synoviolin, also called HRD1, is an E3 ubiquitin ligase and is implicated in endoplasmic reticulum -associated degradation. In mammals, Synoviolin plays crucial roles in various physiological and pathological processes, including embryogenesis and the pathogenesis of arthropathy. However, little is known about the molecular mechanisms of Synoviolin in these actions. To clarify these issues, we analyzed the profile of protein expression in synoviolin-null cells. Here, we report that Synoviolin targets tumor suppressor gene p53 for ubiquitination. Synoviolin sequestrated and metabolized p53 in the cytoplasm and negatively regulated its cellular level and biological functions, including transcription, cell cycle regulation and apoptosis. Furthermore, these p53 regulatory functions of Synoviolin were irrelevant to other E3 ubiquitin ligases for p53, such as MDM2, Pirh2 and Cop1, which form autoregulatory feedback loops. Our results provide novel insights into p53 signaling mediated by Synoviolin. PMID:17170702
Cytoplasmic destruction of p53 by the endoplasmic reticulum-resident ubiquitin ligase 'Synoviolin'.

PubMed

Yamasaki, Satoshi; Yagishita, Naoko; Sasaki, Takeshi; Nakazawa, Minako; Kato, Yukihiro; Yamadera, Tadayuki; Bae, Eunkyung; Toriyama, Sayumi; Ikeda, Rie; Zhang, Lei; Fujitani, Kazuko; Yoo, Eunkyung; Tsuchimochi, Kaneyuki; Ohta, Tomohiko; Araya, Natsumi; Fujita, Hidetoshi; Aratani, Satoko; Eguchi, Katsumi; Komiya, Setsuro; Maruyama, Ikuro; Higashi, Nobuyo; Sato, Mitsuru; Senoo, Haruki; Ochi, Takahiro; Yokoyama, Shigeyuki; Amano, Tetsuya; Kim, Jaeseob; Gay, Steffen; Fukamizu, Akiyoshi; Nishioka, Kusuki; Tanaka, Keiji; Nakajima, Toshihiro

2007-01-10

Synoviolin, also called HRD1, is an E3 ubiquitin ligase and is implicated in endoplasmic reticulum -associated degradation. In mammals, Synoviolin plays crucial roles in various physiological and pathological processes, including embryogenesis and the pathogenesis of arthropathy. However, little is known about the molecular mechanisms of Synoviolin in these actions. To clarify these issues, we analyzed the profile of protein expression in synoviolin-null cells. Here, we report that Synoviolin targets tumor suppressor gene p53 for ubiquitination. Synoviolin sequestrated and metabolized p53 in the cytoplasm and negatively regulated its cellular level and biological functions, including transcription, cell cycle regulation and apoptosis. Furthermore, these p53 regulatory functions of Synoviolin were irrelevant to other E3 ubiquitin ligases for p53, such as MDM2, Pirh2 and Cop1, which form autoregulatory feedback loops. Our results provide novel insights into p53 signaling mediated by Synoviolin.
ATF3 activates Stat3 phosphorylation through inhibition of p53 expression in skin cancer cells.

PubMed

Hao, Zhen-Feng; Ao, Jun-Hong; Zhang, Jie; Su, You-Ming; Yang, Rong-Ya

2013-01-01

ATF3, a member of the ATF/CREB family of transcription factors, has been found to be selectively induced by calcineurin/NFAT inhibition and to enhance keratinocyte tumor formation, although the precise role of ATF3 in human skin cancer and possible mechanisms remain unknown. In this study, clinical analysis of 30 skin cancer patients and 30 normal donors revealed that ATF3 was accumulated in skin cancer tissues. Functional assays demonstrated that ATF3 significantly promoted skin cancer cell proliferation. Mechanically, ATF3 activated Stat3 phosphorylation in skin cancer cell through regulation of p53 expression. Moreover, the promotion effect of ATF3 on skin cancer cell proliferation was dependent on the p53-Stat3 signaling cascade. Together, the results indicate that ATF3 might promote skin cancer cell proliferation and enhance skin keratinocyte tumor development through inhibiting p53 expression and then activating Stat3 phosphorylation.
Involvement of p53 and Bcl-2 in sensory cell degeneration in aging rat cochleae.

PubMed

Xu, Yang; Yang, Wei Ping; Hu, Bo Hua; Yang, Shiming; Henderson, Donald

2017-06-01

p53 and Bcl-2 (B-cell lymphoma 2) are involved in the process of sensory cell degeneration in aging cochleae. To determine molecular players in age-related hair cell degeneration, this study examined the changes in p53 and Bcl-2 expression at different stages of apoptotic and necrotic death of hair cells in aging rat cochleae. Young (3-4 months) and aging (23-24 months) Fisher 344/NHsd rats were used. The thresholds of the auditory brainstem response (ABR) were measured to determine the auditory function. Immunolabeling was performed to determine the expression of p53 and Bcl-2 proteins in the sensory epithelium. Propidium iodide staining was performed to determine the morphologic changes in hair cell nuclei. Aging rats exhibited a significant elevation in ABR thresholds at all tested frequencies (p < 0.001). The p53 and Bcl-2 immunoreactivity was increased in aging hair cells showing the early signs of apoptotic changes in their nuclei. The Bcl-2 expression increase was also observed in hair cells displaying early signs of necrosis. As the hair cell degenerative process advanced, p53 and Bcl-2 immunoreactivity became reduced or absent. In the areas where no detectable nuclear staining was present, p53 and Bcl-2 immunoreactivity was absent.
p53-dependent control of cell death by nicastrin: lack of requirement for presenilin-dependent gamma-secretase complex.

PubMed

Pardossi-Piquard, Raphaëlle; Dunys, Julie; Giaime, Emilie; Guillot-Sestier, Marie-Victoire; St George-Hyslop, Peter; Checler, Frédéric; Alves da Costa, Cristine

2009-04-01

Nicastrin (NCT) is a component of the presenilin (PS)-dependent gamma-secretase complexes that liberate amyloid beta-peptides from the beta-Amyloid Precursor Protein. Several lines of evidence indicate that the members of these complexes could also contribute to the control of cell death. Here we show that over-expression of NCT increases the viability of human embryonic kidney (HEK293) cells and decreases staurosporine (STS)- and thapsigargin (TPS)-induced caspase-3 activation in various cell lines from human and neuronal origins by Akt-dependent pathway. NCT lowers p53 expression, transcriptional activity and promoter transactivation and reduces p53 phosphorylation. NCT-associated protection against STS-stimulated cell death was completely abolished by p53 deficiency. Conversely, the depletion of NCT drastically enhances STS-induced caspase-3 activation and p53 pathway and favored p53 nuclear translocation. We examined whether NCT protective function depends on PS-dependent gamma-secretase activity. First, a 29-amino acid deletion known to reduce NCT-dependent amyloid beta-peptide production did not affect NCT-associated protective phenotype. Second, NCT still reduces STS-induced caspase-3 activation in fibroblasts lacking PS1 and PS2. Third, the gamma-secretase inhibitor DFK167 did not affect NCT-mediated reduction of p53 activity. Altogether, our study indicates that NCT controls cell death via phosphoinositide 3-kinase/Akt and p53-dependent pathways and that this function remains independent of the activity and molecular integrity of the gamma-secretase complexes.
p53 Protein interacts specifically with the meiosis-specific mammalian RecA-like protein DMC1 in meiosis.

PubMed

Habu, Toshiyuki; Wakabayashi, Nobunao; Yoshida, Kayo; Yomogida, Kenntaro; Nishimune, Yoshitake; Morita, Takashi

2004-06-01

The tumor suppressor protein p53 is specifically expressed during meiosis in spermatocytes. Subsets of p53 knockout mice exhibit testicular giant cell degenerative syndrome, which suggests p53 may be associated with meiotic cell cycle and/or DNA metabolism. Here, we show that p53 binds to the mouse meiosis-specific RecA-like protein Mus musculus DMC1 (MmDMC1). The C-terminal domain (amino acid 234-340) of MmDMC1 binds to DNA-binding domain of p53 protein. p53 might be involved in homologous recombination and/or checkpoint function by directly binding to DMC1 protein to repress genomic instability in meiotic germ cells.
The expanding universe of p53 targets.

PubMed

Menendez, Daniel; Inga, Alberto; Resnick, Michael A

2009-10-01

The p53 tumour suppressor is modified through mutation or changes in expression in most cancers, leading to the altered regulation of hundreds of genes that are directly influenced by this sequence-specific transcription factor. Central to the p53 master regulatory network are the target response element (RE) sequences. The extent of p53 transactivation and transcriptional repression is influenced by many factors, including p53 levels, cofactors and the specific RE sequences, all of which contribute to the role that p53 has in the aetiology of cancer. This Review describes the identification and functionality of REs and highlights the inclusion of non-canonical REs that expand the universe of genes and regulation mechanisms in the p53 tumour suppressor network.
Residues in the alternative reading frame tumor suppressor that influence its stability and p53-independent activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tommaso, Anne di; Hagen, Jussara; Tompkins, Van

2009-04-15

The Alternative Reading Frame (ARF) protein suppresses tumorigenesis through p53-dependent and p53-independent pathways. Most of ARF's anti-proliferative activity is conferred by sequences in its first exon. Previous work showed specific amino acid changes occurred in that region during primate evolution, so we programmed those changes into human p14ARF to assay their functional impact. Two human p14ARF residues (Ala{sup 14} and Thr{sup 31}) were found to destabilize the protein while two others (Val{sup 24} and Ala{sup 41}) promoted more efficient p53 stabilization and activation. Despite those effects, all modified p14ARF forms displayed robust p53-dependent anti-proliferative activity demonstrating there are no significantmore » biological differences in p53-mediated growth suppression associated with simian versus human p14ARF residues. In contrast, p53-independent p14ARF function was considerably altered by several residue changes. Val{sup 24} was required for p53-independent growth suppression whereas multiple residues (Val{sup 24}, Thr{sup 31}, Ala{sup 41} and His{sup 60}) enabled p14ARF to block or reverse the inherent chromosomal instability of p53-null MEFs. Together, these data pinpoint specific residues outside of established p14ARF functional domains that influence its expression and signaling activities. Most intriguingly, this work reveals a novel and direct role for p14ARF in the p53-independent maintenance of genomic stability.« less
MicroRNAs as Key Effectors in the p53 Network.

PubMed

Goeman, Frauke; Strano, Sabrina; Blandino, Giovanni

2017-01-01

The guardian of the genome p53 is embedded in a fine-spun network of MicroRNAs. p53 is able to activate or repress directly the transcription of MicroRNAs that are participating in the tumor-suppressive mission of p53. On the other hand, the expression of p53 is under tight control of MicroRNAs that are either targeting directly p53 or factors that are modifying its protein level or activity. Although the most important function of p53 is suggested to be transcriptional regulation, there are several nontranscriptional functions described. One of those regards the modulation of MicroRNA biogenesis. Wild-type p53 is increasing the maturation of selected MicroRNAs from the primary transcript to the precursor MiRNA by interacting with the Microprocessor complex. Furthermore, p53 is modulating the mRNA accessibility for certain MicroRNAs by association with the RISC complex and transcriptional regulation of RNA-binding proteins. In this way p53 is able to remodel the MiRNA-mRNA interaction network. As wild-type p53 is employing MicroRNAs to suppress cancer development, gain-of-function mutant p53 proteins use MicroRNAs to confer oncogenic properties like chemoresistance and the ability to drive metastasis. Like its wild-type counterpart mutant p53 is able to regulate MicroRNAs transcriptionally and posttranscriptionally. Mutant p53 affects the MiRNA processing at two cleavage steps through interfering with the Microprocessor complex and by downregulating Dicer and KSRP, a modulator of MiRNA biogenesis. Thus, MicroRNAs are essential components in the p53 pathway, contributing substantially to combat or enhance tumor development depending on the wild-type or mutant p53 context. © 2017 Elsevier Inc. All rights reserved.
DNA damage induces down-regulation of Prp19 via impairing Prp19 stability in hepatocellular carcinoma cells.

PubMed

Yin, Jie; Zhang, Yi-An; Liu, Tao-Tao; Zhu, Ji-Min; Shen, Xi-Zhong

2014-01-01

Pre-mRNA processing factor 19 (Prp19) activates pre-mRNA spliceosome and also mediates DNA damage response. Prp19 overexpression in cells with functional p53 leads to decreased apoptosis and increases cell survival after DNA damage. Here we showed that in hepatocellular carcinoma (HCC) cells with inactive p53 or functional p53, Prp19 was down-regulated due to the impaired stability under chemotherapeutic drug treatment. Silencing Prp19 expression enhanced apoptosis of HCC cells with or without chemotherapeutic drug treatment. Furthermore high level of Prp19 may inhibit chemotherapeutic drugs induced apoptosis in hepatocellular carcinoma cells through modulating myeloid leukemia cell differentiation 1 expression. These results indicated that targeting Prp19 may potentiate pro-apoptotic effect of chemotherapeutic agents on HCC.
Wip1 and p53 contribute to HTLV-1 Tax-induced tumorigenesis

PubMed Central

2012-01-01

Background Human T-cell Leukemia Virus type 1 (HTLV-1) infects 20 million individuals world-wide and causes Adult T-cell Leukemia/Lymphoma (ATLL), a highly aggressive T-cell cancer. ATLL is refractory to treatment with conventional chemotherapy and fewer than 10% of afflicted individuals survive more than 5 years after diagnosis. HTLV-1 encodes a viral oncoprotein, Tax, that functions in transforming virus-infected T-cells into leukemic cells. All ATLL cases are believed to have reduced p53 activity although only a minority of ATLLs have genetic mutations in their p53 gene. It has been suggested that p53 function is inactivated by the Tax protein. Results Using genetically altered mice, we report here that Tax expression does not achieve a functional equivalence of p53 inactivation as that seen with genetic mutation of p53 (i.e. a p53−/− genotype). Thus, we find statistically significant differences in tumorigenesis between Tax+p53+/+versus Tax+p53−/− mice. We also find a role contributed by the cellular Wip1 phosphatase protein in tumor formation in Tax transgenic mice. Notably, Tax+Wip1−/− mice show statistically significant reduced prevalence of tumorigenesis compared to Tax+Wip1+/+ counterparts. Conclusions Our findings provide new insights into contributions by p53 and Wip1 in the in vivo oncogenesis of Tax-induced tumors in mice. PMID:23256545
Fusaric Acid Induces DNA Damage and Post-Translational Modifications of p53 in Human Hepatocellular Carcinoma (HepG2 ) Cells.

PubMed

Ghazi, Terisha; Nagiah, Savania; Tiloke, Charlette; Sheik Abdul, Naeem; Chuturgoon, Anil A

2017-11-01

Fusaric acid (FA), a common fungal contaminant of maize, is known to mediate toxicity in plants and animals; however, its mechanism of action is unclear. p53 is a tumor suppressor protein that is activated in response to cellular stress. The function of p53 is regulated by post-translational modifications-ubiquitination, phosphorylation, and acetylation. This study investigated a possible mechanism of FA induced toxicity in the human hepatocellular carcinoma (HepG 2 ) cell line. The effect of FA on DNA integrity and post-translational modifications of p53 were investigated. Methods included: (a) culture and treatment of HepG 2 cells with FA (IC 50 : 580.32 μM, 24 h); (b) comet assay (DNA damage); (c) Western blots (protein expression of p53, MDM2, p-Ser-15-p53, a-K382-p53, a-CBP (K1535)/p300 (K1499), HDAC1 and p-Ser-47-Sirt1); and (d) Hoechst 33342 assay (apoptosis analysis). FA caused DNA damage in HepG 2 cells relative to the control (P < 0.0001). FA decreased the protein expression of p53 (0.24-fold, P = 0.0004) and increased the expression of p-Ser-15-p53 (12.74-fold, P = 0.0126) and a-K382-p53 (2.24-fold, P = 0.0096). This occurred despite the significant decrease in the histone acetyltransferase, a-CBP (K1535)/p300 (K1499) (0.42-fold, P = 0.0023) and increase in the histone deacetylase, p-Ser-47-Sirt1 (1.22-fold, P = 0.0020). The expression of MDM2, a negative regulator of p53, was elevated in the FA treatment compared to the control (1.83-fold, P < 0.0001). FA also inhibited cell proliferation and induced apoptosis in HepG 2 cells as evidenced by the Hoechst assay. Together, these results indicate that FA is genotoxic and post-translationally modified p53 leading to HepG 2 cell death. J. Cell. Biochem. 118: 3866-3874, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Knockdown of p53 suppresses Nanog expression in embryonic stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdelalim, Essam Mohamed, E-mail: emohamed@qf.org.qa; Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192; Department of Cytology and Histology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia

2014-01-10

Highlights: •We investigate the role of p53 in ESCs in the absence of DNA damage. •p53 knockdown suppresses ESC proliferation. •p53 knockdown downregulates Nanog expression. •p53 is essential for mouse ESC self-renewal. -- Abstract: Mouse embryonic stem cells (ESCs) express high levels of cytoplasmic p53. Exposure of mouse ESCs to DNA damage leads to activation of p53, inducing Nanog suppression. In contrast to earlier studies, we recently reported that chemical inhibition of p53 suppresses ESC proliferation. Here, we confirm that p53 signaling is involved in the maintenance of mouse ESC self-renewal. RNA interference-mediated knockdown of p53 induced downregulation of p21more » and defects in ESC proliferation. Furthermore, p53 knockdown resulted in a significant downregulation in Nanog expression at 24 and 48 h post-transfection. p53 knockdown also caused a reduction in Oct4 expression at 48 h post-transfection. Conversely, exposure of ESCs to DNA damage caused a higher reduction of Nanog expression in control siRNA-treated cells than in p53 siRNA-treated cells. These data show that in the absence of DNA damage, p53 is required for the maintenance of mouse ESC self-renewal by regulating Nanog expression.« less

Osteoblast differentiation and skeletal development are regulated by Mdm2–p53 signaling

PubMed Central

Lengner, Christopher J.; Steinman, Heather A.; Gagnon, James; Smith, Thomas W.; Henderson, Janet E.; Kream, Barbara E.; Stein, Gary S.; Lian, Jane B.; Jones, Stephen N.

2006-01-01

Mdm2 is required to negatively regulate p53 activity at the peri-implantation stage of early mouse development. However, the absolute requirement for Mdm2 throughout embryogenesis and in organogenesis is unknown. To explore Mdm2–p53 signaling in osteogenesis, Mdm2-conditional mice were bred with Col3.6-Cre–transgenic mice that express Cre recombinase in osteoblast lineage cells. Mdm2-conditional Col3.6-Cre mice die at birth and display multiple skeletal defects. Osteoblast progenitor cells deleted for Mdm2 have elevated p53 activity, reduced proliferation, reduced levels of the master osteoblast transcriptional regulator Runx2, and reduced differentiation. In contrast, p53-null osteoprogenitor cells have increased proliferation, increased expression of Runx2, increased osteoblast maturation, and increased tumorigenic potential, as mice specifically deleted for p53 in osteoblasts develop osteosarcomas. These results demonstrate that p53 plays a critical role in bone organogenesis and homeostasis by negatively regulating bone development and growth and by suppressing bone neoplasia and that Mdm2-mediated inhibition of p53 function is a prerequisite for Runx2 activation, osteoblast differentiation, and proper skeletal formation. PMID:16533949
Changes in p53 expression in mouse fibroblasts can modify motility and extracellular matrix organization.

PubMed

Alexandrova, A; Ivanov, A; Chumakov, P; Kopnin, B; Vasiliev, J

2000-11-23

Effects of p53 expression on cell morphology and motility were studied using the derivatives of p53-null 10(1) mouse fibroblasts with tetracycline-regulated expression of exogenous human p53. Induction of p53 expression was accompanied by significant decrease in extracellular matrix (fibronectin) and reduction of matrix fibrils, diminution of the number and size of focal contacts, decrease of cell areas, establishment of more elongated cell shape and alterations of actin cytoskeleton (actin bundles became thinner, their number and size decreased). Expression of His175 and Gln22/ Ser23 p53 mutants caused no such effects. To study the influence of p53 expression on cell motility we used wound technique and videomicroscopy observation of single living cells. It was found that induction of p53 expression led to increase of lamellar activity of cell edge. However, in spite of enhanced lamellar activity p53-expressing cells migrated to shorter distance and filled the narrow wound in longer time as compared with their p53-null counterparts. Possible mechanisms of the influence of p53 expression on cell morphology and motility are discussed.
Molecular Dynamic Simulation Insights into the Normal State and Restoration of p53 Function

PubMed Central

Fu, Ting; Min, Hanyi; Xu, Yong; Chen, Jianzhong; Li, Guohui

2012-01-01

As a tumor suppressor protein, p53 plays a crucial role in the cell cycle and in cancer prevention. Almost 50 percent of all human malignant tumors are closely related to a deletion or mutation in p53. The activity of p53 is inhibited by over-active celluar antagonists, especially by the over-expression of the negative regulators MDM2 and MDMX. Protein-protein interactions, or post-translational modifications of the C-terminal negative regulatory domain of p53, also regulate its tumor suppressor activity. Restoration of p53 function through peptide and small molecular inhibitors has become a promising strategy for novel anti-cancer drug design and development. Molecular dynamics simulations have been extensively applied to investigate the conformation changes of p53 induced by protein-protein interactions and protein-ligand interactions, including peptide and small molecular inhibitors. This review focuses on the latest MD simulation research, to provide an overview of the current understanding of interactions between p53 and its partners at an atomic level. PMID:22949826
CP-31398 inhibits the growth of p53-mutated liver cancer cells in vitro and in vivo.

PubMed

He, Xing-Xing; Zhang, Yu-Nan; Yan, Jun-Wei; Yan, Jing-Jun; Wu, Qian; Song, Yu-Hu

2016-01-01

The tumor suppressor p53 is one of the most frequently mutated genes in hepatocellular carcinoma (HCC). Previous studies demonstrated that CP-31398 restored the native conformation of mutant p53 and trans-activated p53 downstream genes in tumor cells. However, the research on the application of CP-31398 to liver cancer has not been reported. Here, we investigated the effects of CP-31398 on the phenotype of HCC cells carrying p53 mutation. The effects of CP-31398 on the characteristic of p53-mutated HCC cells were evaluated through analyzing cell cycle, cell apoptosis, cell proliferation, and the expression of p53 downstream genes. In tumor xenografts developed by PLC/PRF/5 cells, the inhibition of tumor growth by CP-31398 was analyzed through gross morphology, growth curve, and the expression of p53-related genes. Firstly, we demonstrated that CP-31398 inhibited the growth of p53-mutated liver cancer cells in a dose-dependent and p53-dependent manner. Then, further study showed that CP-31398 re-activated wild-type p53 function in p53-mutated HCC cells, which resulted in inhibitive response of cell proliferation and an induction of cell-cycle arrest and apoptosis. Finally, in vivo data confirmed that CP-31398 blocked the growth of xenografts tumors through transactivation of p53-responsive downstream molecules. Our results demonstrated that CP-31398 induced desired phenotypic change of p53-mutated HCC cells in vitro and in vivo, which revealed that CP-31398 would be developed as a therapeutic candidate for HCC carrying p53 mutation.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Amitabh, E-mail: amitabhdas.kn@gmail.com; Chai, Jin Choul, E-mail: jincchai@gmail.com; Jung, Kyoung Hwa, E-mail: khjung2@gmail.com

JMJD2A is a lysine trimethyl-specific histone demethylase that is highly expressed in a variety of tumours. The role of JMJD2A in tumour progression remains unclear. The objectives of this study were to identify JMJD2A-regulated genes and understand the function of JMJD2A in p53-null neuroectodermal stem cells (p53{sup −/−} NE-4Cs). We determined the effect of LPS as a model of inflammation in p53{sup −/−} NE-4Cs and investigated whether the epigenetic modifier JMJD2A alter the expression of tumourigenic inflammatory genes. Global gene expression was measured in JMJD2A knockdown (kd) p53{sup −/−} NE-4Cs and in LPS-stimulated JMJD2A-kd p53{sup −/−} NE-4C cells. JMJD2A attenuationmore » significantly down-regulated genes were Cdca2, Ccnd2, Ccnd1, Crebbp, IL6rα, and Stat3 related with cell cycle, proliferation, and inflammatory-disease responses. Importantly, some tumour-suppressor genes including Dapk3, Timp2 and TFPI were significantly up-regulated but were not affected by silencing of the JMJD2B. Furthermore, we confirmed the attenuation of JMJD2A also down-regulated Cdca2, Ccnd2, Crebbp, and Rest in primary NSCs isolated from the forebrains of E15 embryos of C57/BL6J mice with effective p53 inhibitor pifithrin-α (PFT-α). Transcription factor (TF) motif analysis revealed known binding patterns for CDC5, MYC, and CREB, as well as three novel motifs in JMJD2A-regulated genes. IPA established molecular networks. The molecular network signatures and functional gene-expression profiling data from this study warrants further investigation as an effective therapeutic target, and studies to elucidate the molecular mechanism of JMJD2A-kd-dependent effects in neuroectodermal stem cells should be performed. - Highlights: • Significant up-regulation of epigenetic modifier JMJD2A mRNA upon LPS treatment. • Inhibition of JMJD2A attenuated key inflammatory and tumourigenic genes. • Establishing IPA based functional genomics in JMJD2A-attenuated p53{sup −/−} NE4C cells. • Finding JMJD2A-based molecular targets and crucial pathways in p53{sup −/−} NE4C cells.« less
Regulation of p53 Stability and Apoptosis by a ROR Agonist

PubMed Central

Wang, Yongjun; Solt, Laura A.; Kojetin, Douglas J.; Burris, Thomas P.

2012-01-01

Activation of p53 function leading to cell-cycle arrest and/or apoptosis is a promising strategy for development of anti-cancer therapeutic agents. Here, we describe a novel mechanism for stabilization of p53 protein expression via activation of the orphan nuclear receptor, RORα. We demonstrate that treatment of cancer cells with a newly described synthetic ROR agonist, SR1078, leads to p53 stabilization and induction of apoptosis. These data suggest that synthetic ROR agonists may hold utility in the treatment of cancer. PMID:22509368
Regulation of p53 stability and apoptosis by a ROR agonist.

PubMed

Wang, Yongjun; Solt, Laura A; Kojetin, Douglas J; Burris, Thomas P

2012-01-01

Activation of p53 function leading to cell-cycle arrest and/or apoptosis is a promising strategy for development of anti-cancer therapeutic agents. Here, we describe a novel mechanism for stabilization of p53 protein expression via activation of the orphan nuclear receptor, RORα. We demonstrate that treatment of cancer cells with a newly described synthetic ROR agonist, SR1078, leads to p53 stabilization and induction of apoptosis. These data suggest that synthetic ROR agonists may hold utility in the treatment of cancer.
Discovery and Cocrystal Structure of Benzodiazepinedione HDM2 Antagonists that Activate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grasberger,B.; Lu, T.; Schubert, C.

2005-01-01

HDM2 binds to an {alpha}-helical transactivation domain of p53, inhibiting its tumor suppressive functions. A miniaturized thermal denaturation assay was used to screen chemical libraries, resulting in the discovery of a novel series of benzodiazepinedione antagonists of the HDM2-p53 interaction. The X-ray crystal structure of improved antagonists bound to HDM2 reveals their {alpha}-helix mimetic properties. These optimized molecules increase the transcription of p53 target genes and decrease proliferation of tumor cells expressing wild-type p53.
Curcumin causes superoxide anion production and p53-independent apoptosis in human colon cancer cells.

PubMed

Watson, Jane L; Hill, Richard; Yaffe, Paul B; Greenshields, Anna; Walsh, Mark; Lee, Patrick W; Giacomantonio, Carman A; Hoskin, David W

2010-11-01

Curcumin from the rhizome of theCurcuma longa plant has chemopreventative activity and inhibits the growth of neoplastic cells. Since p53 has been suggested to be important for anticancer activity by curcumin, we investigated curcumin-induced cytotoxicity in cultures of p53(+/+) and p53(-/-) HCT-116 colon cancer cells, as well as mutant p53 HT-29 colon cancer cells. Curcumin killed wild-type p53 HCT-116 cells and mutant p53 HT-29 cells in a dose- and time-dependent manner. In addition, curcumin-treated p53(+/+) HCT-116 cells and mutant p53 HT-29 cells showed upregulation of total and activated p53, as well as increased expression of p53-regulated p21, PUMA (p53 upregulated modulator of apoptosis), and Bax; however, an equivalent cytotoxic effect by curcumin was observed in p53(+/+) and p53(-/-) HCT-116 cells, demonstrating that curcumin-induced cytotoxicity was independent of p53 status. Similar results were obtained when the cytotoxic effect of curcumin was assessed in wild-type p53 HCT-116 cells after siRNA-mediated p53 knockdown. Chromatin condensation, poly (ADP-ribose) polymerase-1 cleavage and reduced pro-caspase-3 levels in curcumin-treated p53(+/+) and p53(-/-) HCT-116 cells suggested that curcumin caused apoptosis. In addition, exposure to curcumin resulted in superoxide anion production and phosphorylation of oxidative stress proteins in p53(+/+) and p53(-/-) HCT-116 cells. Collectively, our results indicate that, despite p53 upregulation and activation, curcumin-induced apoptosis in colon cancer cells was independent of p53 status and involved oxidative stress. Curcumin may therefore have therapeutic potential in the management of colon cancer, especially in tumorsthatare resistant to conventional chemotherapydue todefects inp53 expression or function. 2010 Elsevier Ireland Ltd. All rights reserved.
Loss of p53 Promotes Anaplasia and Local Invasion in ret/PTC1-Induced Thyroid Carcinomas

PubMed Central

La Perle, Krista M. D.; Jhiang, Sissy M.; Capen, Charles C.

2000-01-01

Papillary thyroid carcinomas in humans are associated with the ret/PTC oncogene and, following loss of p53 function, may progress to anaplastic carcinomas. Mice with thyroid-targeted expression of ret/PTC1 developed papillary thyroid carcinomas that were minimally invasive and did not metastasize. These mice were crossed with p53−/− mice to investigate whether loss of p53 would promote anaplasia and metastasis of ret/PTC1-induced thyroid tumors. The majority of p53−/− mice died or were euthanized by 17 weeks of age due to the development of thymic lymphomas, soft tissue sarcomas, and testicular teratomas. All ret/PTC1 mice developed thyroid carcinomas, but tumors in p53−/− mice were more anaplastic, larger in diameter, more invasive, and had a higher mitotic index than tumors in p53+/+ and p53+/− mice. Thyroid tumors did not metastasize in any of the experimental p53+/+ and p53+/− mice ≤28 weeks of age or p53−/− mice ≤ 17 weeks of age; however, an older (170-day-old) male p53−/− mouse used to maintain the colony developed anaplastic thyroid carcinoma with liver metastases. These findings demonstrate that the lack of functional p53 in ret/PTC1 mice promotes anaplasia and invasiveness of thyroid carcinomas. PMID:10934169
Immunohistochemical analysis of P53 protein in odontogenic cysts

PubMed Central

Gaballah, Essam Taher M.A.; Tawfik, Mohamed A.

2010-01-01

The p53 is a well-known tumor suppressor gene, the mutations of which are closely related to the decreased differentiation of cells. Findings of studies on immunohistochemical P53 expression in odontogenic cysts are controversial. The present study was carried-out to investigate the immunohistochemical expression of P53 protein in odontogenic cysts. Thirty paraffin blocks of diagnosed odontogenic cysts were processed to determine the immunohistochemical expression of P53 protein. Nine of the 11 odontogenic keratocysts (81.8%) expressed P53, one of three dentigerous cyst cases expressed P53, while none of the 16 radicular cysts expressed P53 protein. The findings of the present work supported the reclassification of OKC as keratocystic odontogenic tumor. PMID:23960493
Tumorigenic potential of pituitary tumor transforming gene (PTTG) in vivo investigated using a transgenic mouse model, and effects of cross breeding with p53 (+/-) transgenic mice.

PubMed

Fong, Miranda Y; Farghaly, Hanan; Kakar, Sham S

2012-11-20

Pituitary tumor-transforming gene (PTTG) is an oncogene that is overexpressed in variety of tumors and exhibits characteristics of a transforming gene. Previous transgenic mouse models to access the tumorigenic potential in the pituitary and ovary have resulted in dysplasia without formation of visible tumors, possibly due to the insufficient expression of PTTG. PTTG expression level is critical for ovarian tumorigenesis in a xenograft model. Therefore, the tumorigenic function of PTTG in vivo remains unclear. We generated a transgenic mouse that overexpresses PTTG driven by the CMV promoter to determine whether PTTG functions as a transforming oncogene that is capable of initiating tumorigenesis. Transgenic animals were generated by microinjection of PTTG transgene into the male pronucleus of FVB 0.5 day old embryos. Expression levels of PTTG in tissues of transgenic animals were analyzed using an immunohistochemical analysis. H&E staining and immunohistostaining were performed to examine the type of tumor in transgenic and PTTG transgenic/p53+/- animals. PTTG transgenic offspring (TgPTTG) were monitored for tumor development at various ages. H&E analysis was performed to identify the presence of cancer and hyperplastic conditions verified with the proliferation marker PCNA and the microvessel marker CD31. Immunohistochemistry was performed to determine transgene expression, revealing localization to the epithelium of the fallopian tube, with more generalized expression in the liver, lung, kidney, and spleen. At eight months of age, 2 out of 15 TgPTTG developed ovarian cancer, 2 out of 15 developed benign tumors, 2 out of 15 developed cervical dysplasia, and 3 out of 15 developed adenomyosis of the uterus. At ten months of age, 2 out of 10 TgPTTG developed adenocarcinoma of the ovary, 1 out of 10 developed a papillary serous adenocarcinoma, and 2 out of 10 presented with atypia of ovarian epithelial cells. Tumorigenesis is a multi-step process, often requiring multiple oncogenes and/or inactivation of tumor suppressor genes. Therefore, to understand the contribution of p53 to PTTG induced tumorigenesis, we crossbred TgPTTG to p53+/- mice and maintained those 8 to 10 months. TgPTTG/p53+/- animals developed sarcomas faster than p53+/- alone as well as different tumor types in addition to cervical carcinomas in situ in 10 out of 17 females. We conclude that while PTTG is a functional transforming oncogene, it requires an additional partner to effectively promote tumorigenesis through the loss of p53 include or between function or modulation.
Human T-cell leukemia virus type-1-encoded protein HBZ represses p53 function by inhibiting the acetyltransferase activity of p300/CBP and HBO1

PubMed Central

Hoang, Kimson; Ankney, John A.; Nguyen, Stephanie T.; Rushing, Amanda W.; Polakowski, Nicholas; Miotto, Benoit; Lemasson, Isabelle

2016-01-01

Adult T-cell leukemia (ATL) is an often fatal malignancy caused by infection with the complex retrovirus, human T-cell Leukemia Virus, type 1 (HTLV-1). In ATL patient samples, the tumor suppressor, p53, is infrequently mutated; however, it has been shown to be inactivated by the viral protein, Tax. Here, we show that another HTLV-1 protein, HBZ, represses p53 activity. In HCT116 p53+/+ cells treated with the DNA-damaging agent, etoposide, HBZ reduced p53-mediated activation of p21/CDKN1A and GADD45A expression, which was associated with a delay in G2 phase-arrest. These effects were attributed to direct inhibition of the histone acetyltransferase (HAT) activity of p300/CBP by HBZ, causing a reduction in p53 acetylation, which has be linked to decreased p53 activity. In addition, HBZ bound to, and inhibited the HAT activity of HBO1. Although HBO1 did not acetylate p53, it acted as a coactivator for p53 at the p21/CDKN1A promoter. Therefore, through interactions with two separate HAT proteins, HBZ impairs the ability of p53 to activate transcription. This mechanism may explain how p53 activity is restricted in ATL cells that do not express Tax due to modifications of the HTLV-1 provirus, which accounts for a majority of patient samples. PMID:26625199
PRAP1 is a novel executor of p53-dependent mechanisms in cell survival after DNA damage

PubMed Central

Huang, B H; Zhuo, J L; Leung, C H W; Lu, G D; Liu, J J; Yap, C T; Hooi, S C

2012-01-01

p53 has a crucial role in governing cellular mechanisms in response to a broad range of genotoxic stresses. During DNA damage, p53 can either promote cell survival by activating senescence or cell-cycle arrest and DNA repair to maintain genomic integrity for cell survival or direct cells to undergo apoptosis to eliminate extensively damaged cells. The ability of p53 to execute these two opposing cell fates depends on distinct signaling pathways downstream of p53. In this study, we showed that under DNA damage conditions induced by chemotherapeutic drugs, gamma irradiation and hydrogen peroxide, p53 upregulates a novel protein, proline-rich acidic protein 1 (PRAP1). We identified functional p53-response elements within intron 1 of PRAP1 gene and showed that these regions interact directly with p53 using ChIP assays, indicating that PRAP1 is a novel p53 target gene. The induction of PRAP1 expression by p53 may promote resistance of cancer cells to chemotherapeutic drugs such as 5-fluorouracil (5-FU), as knockdown of PRAP1 increases apoptosis in cancer cells after 5-FU treatment. PRAP1 appears to protect cells from apoptosis by inducing cell-cycle arrest, suggesting that the induction of PRAP1 expression by p53 in response to DNA-damaging agents contributes to cancer cell survival. Our findings provide a greater insight into the mechanisms underlying the pro-survival role of p53 in response to cytotoxic treatments. PMID:23235459
PRAP1 is a novel executor of p53-dependent mechanisms in cell survival after DNA damage.

PubMed

Huang, B H; Zhuo, J L; Leung, C H W; Lu, G D; Liu, J J; Yap, C T; Hooi, S C

2012-12-13

p53 has a crucial role in governing cellular mechanisms in response to a broad range of genotoxic stresses. During DNA damage, p53 can either promote cell survival by activating senescence or cell-cycle arrest and DNA repair to maintain genomic integrity for cell survival or direct cells to undergo apoptosis to eliminate extensively damaged cells. The ability of p53 to execute these two opposing cell fates depends on distinct signaling pathways downstream of p53. In this study, we showed that under DNA damage conditions induced by chemotherapeutic drugs, gamma irradiation and hydrogen peroxide, p53 upregulates a novel protein, proline-rich acidic protein 1 (PRAP1). We identified functional p53-response elements within intron 1 of PRAP1 gene and showed that these regions interact directly with p53 using ChIP assays, indicating that PRAP1 is a novel p53 target gene. The induction of PRAP1 expression by p53 may promote resistance of cancer cells to chemotherapeutic drugs such as 5-fluorouracil (5-FU), as knockdown of PRAP1 increases apoptosis in cancer cells after 5-FU treatment. PRAP1 appears to protect cells from apoptosis by inducing cell-cycle arrest, suggesting that the induction of PRAP1 expression by p53 in response to DNA-damaging agents contributes to cancer cell survival. Our findings provide a greater insight into the mechanisms underlying the pro-survival role of p53 in response to cytotoxic treatments.
Classification of TP53 Mutations and HPV Predict Survival in Advanced Larynx Cancer

PubMed Central

Scheel, Adam; Bellile, Emily; McHugh, Jonathan B.; Walline, Heather M.; Prince, Mark E.; Urba, Susan; Wolf, Gregory T.; Eisbruch, Avraham; Worden, Francis; Carey, Thomas E.; Bradford, Carol

2016-01-01

OBJECTIVE Assess TP53 functional mutations in the context of other biomarkers in advanced larynx cancer. STUDY DESIGN Prospective analysis of pretreatment tumor TP53, HPV, Bcl-xL and cyclin D1 status in stage III and IV larynx cancer patients in a clinical trial. METHODS TP53 exons 4-9 from 58 tumors were sequenced. Mutations were grouped using three classifications based on their expected function. Each functional group was analyzed for response to induction chemotherapy, time to surgery, survival, HPV status, p16INK4a, Bcl-xl and cyclin D1 expression. RESULTS TP53 Mutations were found in 22/58 (37.9%) patients with advanced larynx cancer, including missense mutations in 13/58 (22.4%) patients, nonsense mutations in 4/58 (6.9%), and deletions in 5/58 (8.6%). High risk HPV was found in 20/52 (38.5%) tumors. A classification based on crystal Evolutionary Action score of p53 (EAp53) distinguished missense mutations with high risk for decreased survival from low risk mutations (p=0.0315). A model including this TP53 classification, HPV status, cyclin D1 and Bcl-xL staining significantly predicts survival (p=0.0017). CONCLUSION EAp53 functional classification of TP53 mutants and biomarkers predict survival in advanced larynx cancer. PMID:27345657
Transcriptional Inhibition of the Human Papilloma Virus Reactivates Tumor Suppressor p53 in Cervical Carcinoma Cells

PubMed Central

Kochetkov, D. V.; Ilyinskaya, G. V.; Komarov, P. G.; Strom, E.; Agapova, L. S.; Ivanov, A. V.; Budanov, A. V.; Frolova, E. I.; Chumakov, P. M.

2009-01-01

Inactivation of tumor suppressor p53 accompanies the majority of human malignancies. Restoration of p53 function causes death of tumor cells and is potentially suitable for gene therapy of cancer. In cervical carcinoma, human papilloma virus (HPV) E6 facilitates proteasomal degradation of p53. Hence, a possible approach to p53 reactivation is the use of small molecules suppressing the function of viral proteins. HeLa cervical carcinoma cells (HPV-18) with a reporter construct containing the b-galactosidase gene under the control of a p53-responsive promoter were used as a test system to screen a library of small molecules for restoration of the transcriptional activity of p53. The effect of the two most active compounds was studied with cell lines differing in the state of p53-dependent signaling pathways. The compounds each specifically activated p53 in cells expressing HPV-18 and, to a lesser extent, HPV-16 and exerted no effect on control p53-negative cells or cells with the intact p53-dependent pathways. Activation of p53 in cervical carcinoma cells was accompanied by induction of p53-dependent CDKN1 (p21), inhibition of cell proliferation, and induction of apoptosis. In addition, the two compounds dramatically decreased transcription of the HPV genome, which was assumed to cause p53 reactivation. The compounds were low-toxic for normal cells and can be considered as prototypes of new anticancer drugs. PMID:17685229
The p53-reactivating small molecule RITA induces senescence in head and neck cancer cells.

PubMed

Chuang, Hui-Ching; Yang, Liang Peng; Fitzgerald, Alison L; Osman, Abdullah; Woo, Sang Hyeok; Myers, Jeffrey N; Skinner, Heath D

2014-01-01

TP53 is the most commonly mutated gene in head and neck cancer (HNSCC), with mutations being associated with resistance to conventional therapy. Restoring normal p53 function has previously been investigated via the use of RITA (reactivation of p53 and induction of tumor cell apoptosis), a small molecule that induces a conformational change in p53, leading to activation of its downstream targets. In the current study we found that RITA indeed exerts significant effects in HNSCC cells. However, in this model, we found that a significant outcome of RITA treatment was accelerated senescence. RITA-induced senescence in a variety of p53 backgrounds, including p53 null cells. Also, inhibition of p53 expression did not appear to significantly inhibit RITA-induced senescence. Thus, this phenomenon appears to be partially p53-independent. Additionally, RITA-induced senescence appears to be partially mediated by activation of the DNA damage response and SIRT1 (Silent information regulator T1) inhibition, with a synergistic effect seen by combining either ionizing radiation or SIRT1 inhibition with RITA treatment. These data point toward a novel mechanism of RITA function as well as hint to its possible therapeutic benefit in HNSCC.
p53/PUMA expression in human pulmonary fibroblasts mediates cell activation and migration in silicosis.

PubMed

Wang, Wei; Liu, Haijun; Dai, Xiaoniu; Fang, Shencun; Wang, Xingang; Zhang, Yingming; Yao, Honghong; Zhang, Xilong; Chao, Jie

2015-11-18

Phagocytosis of SiO2 into the lung causes an inflammatory cascade that results in fibroblast proliferation and migration, followed by fibrosis. Clinical evidence has indicated that the activation of alveolar macrophages by SiO2 produces rapid and sustained inflammation characterized by the generation of monocyte chemotactic protein 1, which, in turn, induces fibrosis. However, the details of events downstream of monocyte chemotactic protein 1 activity in pulmonary fibroblasts remain unclear. Here, to elucidate the role of p53 in fibrosis induced by silica, both the upstream molecular mechanisms and the functional effects on cell proliferation and migration were investigated. Experiments using primary cultured adult human pulmonary fibroblasts led to the following results: 1) SiO2 treatment resulted in a rapid and sustained increase in p53 and PUMA protein levels; 2) the MAPK and PI3K pathways were involved in the SiO2-induced alteration of p53 and PUMA expression; and 3) RNA interference targeting p53 and PUMA prevented the SiO2-induced increases in fibroblast activation and migration. Our study elucidated a link between SiO2-induced p53/PUMA expression in fibroblasts and cell migration, thereby providing novel insight into the potential use of p53/PUMA in the development of novel therapeutic strategies for silicosis treatment.
Functional activation of mutant p53V172F by platinum analogs in cisplatin-resistant human tumor cells is dependent on serine-20 phosphorylation

PubMed Central

Xie, Xiaolei; He, Guangan; Siddik, Zahid H.

2017-01-01

Dysfunctionality of the p53 tumor suppressor is a major cause of therapeutic drug resistance in cancer. Recently we reported that mutant, but otherwise functional, p53V172F was inactivated in cisplatin-resistant 2780CP/Cl-16 and 2780CP/Cl-24 human ovarian tumor cells by increased recruitment of the inhibitor MDM4. The current study demonstrates that, unlike cisplatin, platinum analogs oxaliplatin and DACH-diacetato-dichloro-Pt(IV) (DAP), strongly stabilize and activate p53V172F in resistant cells, as indicated by prolonged p53 half-life and transactivation of targets p21 (CDKN1A) and MDM2. This increase in MDM2 reduced MDM4 levels in cell lysates as well as the p53 immunocomplex and prevented reversion of p53 to the inactive p53-MDM2-MDM4 bound state. Phosphorylation of p53 at Ser15 was demonstrated by all three drugs in sensitive A2780 and corresponding resistant 2780CP/Cl-16 and 2780CP/Cl-24 cell lines. However, cisplatin induced Ser20 phosphorylation in A2780 cells only, but not in resistant cells; in contrast, both DAP and oxaliplatin induced this phosphorylation in all three cell lines. The inference that Ser20 phosphorylation is more important for p53 activation was confirmed by ectopic expression of a phosphomimetic (S20D) mutant p53 that displayed reduced binding, relative to wild-type p53, to both MDM2 and MDM4 in p53-knockout A2780 cells. In consonance, temporal studies demonstrated drug-induced Ser15 phosphorylation coincided with p53 stabilization, whereas Ser20 phosphorylation coincided with p53 transactivation. Implications Cisplatin fails to activate the pathway involved in phosphorylating mutant p53V172F at Ser20 in resistant cells, but this phosphorylation is restored by oxaliplatin and DAP that reactivates p53 function and circumvents cisplatin resistance. PMID:28031409

Distinct tumor protein p53 mutants in breast cancer subgroups.

PubMed

Dumay, Anne; Feugeas, Jean-Paul; Wittmer, Evelyne; Lehmann-Che, Jacqueline; Bertheau, Philippe; Espié, Marc; Plassa, Louis-François; Cottu, Paul; Marty, Michel; André, Fabrice; Sotiriou, Christos; Pusztai, Lajos; de Thé, Hugues

2013-03-01

Tumor protein p53 (TP53) is mutated in approximately 30% of breast cancers, but this frequency fluctuates widely between subclasses. We investigated the p53 mutation status in 572 breast tumors, classified into luminal, basal and molecular apocrine subgroups. As expected, the lowest mutation frequency was observed in luminal (26%), and the highest in basal (88%) tumors. Luminal tumors showed significantly higher frequency of substitutions (82 vs. 65%), notably A/T to G/C transitions (31 vs. 15%), whereas molecular apocrine and basal tumors presented much higher frequencies of complex mutations (deletions/insertions) (36 and 33%, respectively, vs. 18%). Accordingly, missense mutations were significantly more frequent in luminal tumors (75 vs. 54%), whereas basal tumors displayed significantly increased rates of TP53 truncations (43 vs. 25%), resulting in loss of function and/or expression. Interestingly, as basal tumors, molecular apocrine tumors presented with a high rate of complex mutations, but paradoxically, these were not associated with increased frequency of p53 truncation. As in luminal tumors, this could reflect a selective pressure for p53 gain of function, possibly through P63/P73 inactivation. Collectively, these observations point not only to different mechanisms of TP53 alterations, but also to different functional consequences in the different breast cancer subtypes. Copyright © 2012 UICC.
Acentriolar mitosis activates a p53-dependent apoptosis pathway in the mouse embryo

PubMed Central

Bazzi, Hisham; Anderson, Kathryn V.

2014-01-01

Centrosomes are the microtubule-organizing centers of animal cells that organize interphase microtubules and mitotic spindles. Centrioles are the microtubule-based structures that organize centrosomes, and a defined set of proteins, including spindle assembly defective-4 (SAS4) (CPAP/CENPJ), is required for centriole biogenesis. The biological functions of centrioles and centrosomes vary among animals, and the functions of mammalian centrosomes have not been genetically defined. Here we use a null mutation in mouse Sas4 to define the cellular and developmental functions of mammalian centrioles in vivo. Sas4-null embryos lack centrosomes but survive until midgestation. As expected, Sas4−/− mutants lack primary cilia and therefore cannot respond to Hedgehog signals, but other developmental signaling pathways are normal in the mutants. Unlike mutants that lack cilia, Sas4−/− embryos show widespread apoptosis associated with global elevated expression of p53. Cell death is rescued in Sas4−/− p53−/− double-mutant embryos, demonstrating that mammalian centrioles prevent activation of a p53-dependent apoptotic pathway. Expression of p53 is not activated by abnormalities in bipolar spindle organization, chromosome segregation, cell-cycle profile, or DNA damage response, which are normal in Sas4−/− mutants. Instead, live imaging shows that the duration of prometaphase is prolonged in the mutants while two acentriolar spindle poles are assembled. Independent experiments show that prolonging spindle assembly is sufficient to trigger p53-dependent apoptosis. We conclude that a short delay in the prometaphase caused by the absence of centrioles activates a previously undescribed p53-dependent cell death pathway in the rapidly dividing cells of the mouse embryo. PMID:24706806
TRIM65 negatively regulates p53 through ubiquitination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yang; Ma, Chengyuan; Zhou, Tong

2016-04-22

Tripartite-motif protein family member 65 (TRIM65) is an important protein involved in white matter lesion. However, the role of TRIM65 in human cancer remains less understood. Through the Cancer Genome Atlas (TCGA) gene alteration database, we found that TRIM65 is upregulated in a significant portion of non-small cell lung carcinoma (NSCLC) patients. Our cell growth assay revealed that TRIM65 overexpression promotes cell proliferation, while knockdown of TRIM65 displays opposite effect. Mechanistically, TRIM65 binds to p53, one of the most critical tumor suppressors, and serves as an E3 ligase toward p53. Consequently, TRIM65 inactivates p53 through facilitating p53 poly-ubiquitination and proteasome-mediatedmore » degradation. Notably, chemotherapeutic reagent cisplatin induction of p53 is markedly attenuated in response to ectopic expression of TRIM65. Cell growth inhibition by TRIM65 knockdown is more significant in p53 positive H460 than p53 negative H1299 cells, and knockdown of p53 in H460 cells also shows compromised cell growth inhibition by TRIM65 knockdown, indicating that p53 is required, at least in part, for TRIM65 function. Our findings demonstrate TRIM65 as a potential oncogenic protein, highly likely through p53 inactivation, and provide insight into development of novel approaches targeting TRIM65 for NSCLC treatment, and also overcoming chemotherapy resistance. - Highlights: • TRIM65 expression is elevated in NSCLC. • TRIM65 inactivates p53 through mediating p53 ubiquitination and degradation. • TRIM65 attenuates the response of NSCLC cells to cisplatin.« less
L'effet de p53 sur la radiosensibilité des cellules humaines normales et cancéreuses

NASA Astrophysics Data System (ADS)

Little, J. B.; Li, C. Y.; Nagasawa, H.; Huang, H.

1998-04-01

The radiosensitivity of normal human fibroblasts in p53 dependent and associated with the loss of cells from the cycling population as the result of an irreversible G1 arrest; cells lacking normal p53 function show no arrest and are more radioresistant. Under conditions in which the repair potentially lethal radiation damage is facilitated, the fraction of cells arrested in G1 is reduced and survival is enhanced. The response of human tumor cells differs significantly. The radiation-induced G1 arrest is minimal or absent in p53+ tumor cells, and loss of normal p53 function has no consistent effect on their radiosensitivity. These results suggest that p53 status may not be a useful predictive marker for the response of human solid tumors to radiation therapy. La radiosensibilité des fibroblastes diploïdes humains est liée à l'expression de p53, et à la perte de cellules en cycle résultant d'un arrêt irréversible en phase G1 ; dans les cellules n'ayant pas une fonction p53 normale, on ne constate aucun arrêt, et elles sont plus radio-résistantes. Dans des conditions favorables à la réparation de lésions potentiellement léthales dues à l'irradiation, la proportion de cellules bloquées en phase G1 baisse, et les chances de survie sont accrues. Bien différente est la réaction des cellules cancéreuses humaines. Le blocage par irradiation en phase G1 est minime ou inexistant dans les cellules cancéreuses p53^+, et la perte de la fonction normale p53 n'a pas d'effet constant sur leur radiosensibilité. Ces résultats laissent penser que l'expression de p53 n'est pas un indice fiable permettant de prévoir la réaction des tumeurs solides à la radiothérapie.
Rb and p53 Liver Functions Are Essential for Xenobiotic Metabolism and Tumor Suppression

PubMed Central

Nantasanti, Sathidpak; Toussaint, Mathilda J. M.; Youssef, Sameh A.; Tooten, Peter C. J.; de Bruin, Alain

2016-01-01

The tumor suppressors Retinoblastoma (Rb) and p53 are frequently inactivated in liver diseases, such as hepatocellular carcinomas (HCC) or infections with Hepatitis B or C viruses. Here, we discovered a novel role for Rb and p53 in xenobiotic metabolism, which represent a key function of the liver for metabolizing therapeutic drugs or toxins. We demonstrate that Rb and p53 cooperate to metabolize the xenobiotic 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). DDC is metabolized mainly by cytochrome P450 (Cyp)3a enzymes resulting in inhibition of heme synthesis and accumulation of protoporphyrin, an intermediate of heme pathway. Protoporphyrin accumulation causes bile injury and ductular reaction. We show that loss of Rb and p53 resulted in reduced Cyp3a expression decreased accumulation of protoporphyrin and consequently less ductular reaction in livers of mice fed with DDC for 3 weeks. These findings provide strong evidence that synergistic functions of Rb and p53 are essential for metabolism of DDC. Because Rb and p53 functions are frequently disabled in liver diseases, our results suggest that liver patients might have altered ability to remove toxins or properly metabolize therapeutic drugs. Strikingly the reduced biliary injury towards the oxidative stress inducer DCC was accompanied by enhanced hepatocellular injury and formation of HCCs in Rb and p53 deficient livers. The increase in hepatocellular injury might be related to reduce protoporphyrin accumulation, because protoporphrin is well known for its anti-oxidative activity. Furthermore our results indicate that Rb and p53 not only function as tumor suppressors in response to carcinogenic injury, but also in response to non-carcinogenic injury such as DDC. PMID:26967735
Myeloid leukemia factor 1 regulates p53 by suppressing COP1 via COP9 signalosome subunit 3.

PubMed

Yoneda-Kato, Noriko; Tomoda, Kiichiro; Umehara, Mari; Arata, Yukinobu; Kato, Jun-ya

2005-05-04

Myeloid leukemia factor 1 (MLF1) was first identified as the leukemic fusion protein NPM-MLF1 generated by the t(3;5)(q25.1;q34) chromosomal translocation. Although MLF1 expresses normally in a variety of tissues including hematopoietic stem cells and the overexpression of MLF1 correlates with malignant transformation in human cancer, little is known about how MLF1 is involved in the regulation of cell growth. Here we show that MLF1 is a negative regulator of cell cycle progression functioning upstream of the tumor suppressor p53. MLF1 induces p53-dependent cell cycle arrest in murine embryonic fibroblasts. This action requires a novel binding partner, subunit 3 of the COP9 signalosome (CSN3). A reduction in the level of CSN3 protein with small interfering RNA abrogated MLF1-induced G1 arrest and impaired the activation of p53 by genotoxic stress. Furthermore, ectopic MLF1 expression and CSN3 knockdown inversely affect the endogenous level of COP1, a ubiquitin ligase for p53. Exogenous expression of COP1 overcomes MLF1-induced growth arrest. These results indicate that MLF1 is a critical regulator of p53 and suggest its involvement in leukemogenesis through a novel CSN3-COP1 pathway.
Transcriptional analysis of immune-related gene expression in p53-deficient mice with increased susceptibility to influenza A virus infection.

PubMed

Yan, Wenjun; Wei, Jianchao; Deng, Xufang; Shi, Zixue; Zhu, Zixiang; Shao, Donghua; Li, Beibei; Wang, Shaohui; Tong, Guangzhi; Ma, Zhiyong

2015-08-18

p53 is a tumor suppressor that contributes to the host immune response against viral infections in addition to its well-established protective role against cancer development. In response to influenza A virus (IAV) infection, p53 is activated and plays an essential role in inhibiting IAV replication. As a transcription factor, p53 regulates the expression of a range of downstream responsive genes either directly or indirectly in response to viral infection. We compared the expression profiles of immune-related genes between IAV-infected wild-type p53 (p53WT) and p53-deficient (p53KO) mice to gain an insight into the basis of p53-mediated antiviral response. p53KO and p53WT mice were infected with influenza A/Puerto Rico/8/1934 (PR8) strain. Clinical symptoms and body weight changes were monitored daily. Lung specimens of IAV-infected mice were collected for analysis of virus titers and gene expression profiles. The difference in immune-related gene expression levels between IAV-infected p53KO and p53WT mice was comparatively determined using microarray analysis and confirmed by quantitative real-time reverse transcription polymerase chain reaction. p53KO mice showed an increased susceptibility to IAV infection compared to p53WT mice. Microarray analysis of gene expression profiles in the lungs of IAV-infected mice indicated that the increased susceptibility was associated with significantly changed expression levels in a range of immune-related genes in IAV-infected p53KO mice. A significantly attenuated expression of Ifng (encoding interferon (IFN)-gamma), Irf7 (encoding IFN regulator factor 7), and antiviral genes, such as Mx2 and Eif2ak2 (encoding PKR), were observed in IAV-infected p53KO mice, suggesting an impaired IFN-mediated immune response against IAV infection in the absence of p53. In addition, dysregulated expression levels of proinflammatory cytokines and chemokines, such as Ccl2 (encoding MCP-1), Cxcl9, Cxcl10 (encoding IP-10), and Tnf, were detected in IAV-infected p53KO mice during early IAV infection, reflecting an aberrant inflammatory response. Lack of p53 resulted in the impaired expression of genes involved in IFN signaling and the dysregulated expression of cytokine and chemokine genes in IAV-infected mice, suggesting an essential role of p53 in the regulation of antiviral and inflammatory responses during IAV infection.
EMT and induction of miR-21 mediate metastasis development in Trp53-deficient tumours

PubMed Central

Bornachea, Olga; Santos, Mirentxu; Martínez-Cruz, Ana Belén; García-Escudero, Ramón; Dueñas, Marta; Costa, Clotilde; Segrelles, Carmen; Lorz, Corina; Buitrago, Agueda; Saiz-Ladera, Cristina; Agirre, Xabier; Grande, Teresa; Paradela, Beatriz; Maraver, Antonio; Ariza, José M.; Prosper, Felipe; Serrano, Manuel; Sánchez-Céspedes, Montse; Paramio, Jesús M.

2012-01-01

Missense mutations in TP53 gene promote metastasis in human tumours. However, little is known about the complete loss of function of p53 in tumour metastasis. Here we show that squamous cell carcinomas generated by the specific ablation of Trp53 gene in mouse epidermis are highly metastatic. Biochemical and genome-wide mRNA and miRNA analyses demonstrated that metastases are associated with the early induction of epithelial-mesenchymal transition (EMT) and deregulated miRNA expression in primary tumours. Increased expression of miR-21 was observed in undifferentiated, prometastatic mouse tumours and in human tumours characterized by p53 mutations and distant metastasis. The augmented expression of miR-21, mediated by active mTOR and Stat3 signalling, conferred increased invasive properties to mouse keratinocytes in vitro and in vivo, whereas blockade of miR-21 in a metastatic spindle cell line inhibits metastasis development. Collectively these data identify novel molecular mechanisms leading to metastasis in vivo originated by p53 loss in epithelia. PMID:22666537
Effect of Mutant p53 Proteins on Glycolysis and Mitochondrial Metabolism.

PubMed

Eriksson, Matilda; Ambroise, Gorbatchev; Ouchida, Amanda Tomie; Lima Queiroz, Andre; Smith, Dominique; Gimenez-Cassina, Alfredo; Iwanicki, Marcin P; Muller, Patricia A; Norberg, Erik; Vakifahmetoglu-Norberg, Helin

2017-12-15

TP53 is one of the most commonly mutated genes in human cancers. Unlike other tumor suppressors that are frequently deleted or acquire loss-of-function mutations, the majority of TP53 mutations in tumors are missense substitutions, which lead to the expression of full-length mutant proteins that accumulate in cancer cells and may confer unique gain-of-function (GOF) activities to promote tumorigenic events. Recently, mutant p53 proteins have been shown to mediate metabolic changes as a novel GOF to promote tumor development. There is a strong rationale that the GOF activities, including alterations in cellular metabolism, might vary between the different p53 mutants. Accordingly, the effect of different mutant p53 proteins on cancer cell metabolism is largely unknown. In this study, we have metabolically profiled several individual frequently occurring p53 mutants in cancers, focusing on glycolytic and mitochondrial oxidative phosphorylation pathways. Our investigation highlights the diversity of different p53 mutants in terms of their effect on metabolism, which might provide a foundation for the development of more effective targeted pharmacological approaches toward variants of mutant p53. Copyright © 2017 American Society for Microbiology.
Characterizing components of the Saw Palmetto Berry Extract (SPBE) on prostate cancer cell growth and traction.

PubMed

Scholtysek, Carina; Krukiewicz, Aleksandra A; Alonso, José-Luis; Sharma, Karan P; Sharma, Pal C; Goldmann, Wolfgang H

2009-02-13

Saw Palmetto Berry Extract (SPBE) is applied for prostate health and treatment of urinary tract infections, nonbacterial prostitis and Benign Prostatic Hyperplasia (BPH) in man. An assumption is that SPBE affects tumor cell progression and migration in breast and prostate tissue. In this work, DU-145 cells were used to demonstrate that SPBE and its sterol components, beta-sitosterol and stigmasterol, inhibit prostate cancer growth by increasing p53 protein expression and also inhibit carcinoma development by decreasing p21 and p27 protein expression. In the presence of cholesterol, these features are not only reversed but increased significantly. The results show for the first time the potential of SPBE, beta-sitosterol and stigmasterol as potential anti-tumor agents. Since the protein p53 is also regarded as nuclear matrix protein facilitating actin cytoskeletal binding, 2D tractions were measured. The cell adhesion strength in the presence of SPBE, beta-sitosterol and cholesterol and the observation was that the increase in p53 expression triggered an increase in the intracellular force generation. The results suggest a dual function of p53 in cells.
MiR-300 regulate the malignancy of breast cancer by targeting p53.

PubMed

Xu, Xiao-Heng; Li, Da-Wei; Feng, Hui; Chen, Hong-Mei; Song, Yan-Qiu

2015-01-01

In this study, we investigated the role of miR-300 in regulating cell proliferation and invasion of breast cancer (BC) cells. MicroRNA and protein expression patterns were compared between breast cancer tissue and normal tissue and between two different prognostic groups. The up-regulation of miR-300 was confirmed by real-time reverse transcription polymerase chain reaction and its expression was analyzed in MCF-7 breast cancer cells. We observed that miR-300 expression was frequently and dramatically up-regulated in human breast cancer tissues and cell lines compared with the matched adjacent normal tissues and cells. We further showed that transient and stable over-expression of miR-300 could promote cell proliferation and cell cycle progression. Moreover, p53, a key inhibitor of cell cycle, was verified as a direct target of miR-300, suggesting that miR-300 might promote breast cancer cell proliferation and invasion by regulating p53 expression. Our findings indicated that miR-300 up-regulation might exert some sort of antagonistic function by targeting p53 in breast cancer cell proliferation during breast tumorigenesis.
MiR-300 regulate the malignancy of breast cancer by targeting p53

PubMed Central

Xu, Xiao-Heng; Li, Da-Wei; Feng, Hui; Chen, Hong-Mei; Song, Yan-Qiu

2015-01-01

Objective: In this study, we investigated the role of miR-300 in regulating cell proliferation and invasion of breast cancer (BC) cells. Methods: MicroRNA and protein expression patterns were compared between breast cancer tissue and normal tissue and between two different prognostic groups. The up-regulation of miR-300 was confirmed by real-time reverse transcription polymerase chain reaction and its expression was analyzed in MCF-7 breast cancer cells. Results: We observed that miR-300 expression was frequently and dramatically up-regulated in human breast cancer tissues and cell lines compared with the matched adjacent normal tissues and cells. We further showed that transient and stable over-expression of miR-300 could promote cell proliferation and cell cycle progression. Moreover, p53, a key inhibitor of cell cycle, was verified as a direct target of miR-300, suggesting that miR-300 might promote breast cancer cell proliferation and invasion by regulating p53 expression. Conclusion: Our findings indicated that miR-300 up-regulation might exert some sort of antagonistic function by targeting p53 in breast cancer cell proliferation during breast tumorigenesis. PMID:26221232
The p53-p21WAF1 checkpoint pathway plays a protective role in preventing DNA rereplication induced by abrogation of FOXF1 function

PubMed Central

Lo, Pang-Kuo; Lee, Ji Shin; Sukumar, Saraswati

2011-01-01

We previously identified FOXF1 as a potential tumor suppressor gene with an essential role in preventing DNA rereplication to maintain genomic stability, which is frequently inactivated in breast cancer through the epigenetic mechanism. Here we further addressed the role of the p53-p21WAF1 checkpoint pathway in DNA rereplication induced by silencing of FOXF1. Knockdown of FOXF1 by small interference RNA (siRNA) rendered colorectal p53-null and p21WAF1-null HCT116 cancer cells more susceptible to rereplication and apoptosis than the wild-type parental cells. In parental HCT116 cells with a functional p53 checkpoint, the p53-p21WAF1 checkpoint pathway was activated upon FOXF1 knockdown, which was concurrent with suppression of the CDK2-Rb cascade and induction of G1 arrest. In contrast, these events were not observed in FOXF1-depleted HCT116-p53−/− and HCT116-p21−/− cells, indicating the p53-dependent checkpoint function is vital for inhibiting CDK2 to induce G1 arrest and protect cells from rereplication. The pharmacologic inhibitor (caffeine) of Ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3 related (ATR) protein kinases abolished activation of the p53-p21WAF1 pathway upon FOXF1 knockdown, suggesting that suppression of FOXF1 function triggered the ATM/ATR-mediated DNA damage response. Cosilencing of p53 by siRNA synergistically enhanced the effect of FOXF1 depletion on stimulation of DNA rereplication and apoptosis in wild-type HCT116. Finally, we show that FOXF1 expression is predominantly silenced in breast and colorectal cancer cell lines with inactive p53. Our study demonstrated that the p53-p21WAF1 checkpoint pathway is an intrinsically protective mechanism to prevent DNA rereplication induced by silencing of FOXF1. PMID:21964066
Classification of TP53 mutations and HPV predict survival in advanced larynx cancer.

PubMed

Scheel, Adam; Bellile, Emily; McHugh, Jonathan B; Walline, Heather M; Prince, Mark E; Urba, Susan; Wolf, Gregory T; Eisbruch, Avraham; Worden, Francis; Carey, Thomas E; Bradford, Carol

2016-09-01

Assess tumor suppressor p53 (TP53) functional mutations in the context of other biomarkers in advanced larynx cancer. Prospective analysis of pretreatment tumor TP53, human papillomavirus (HPV), Bcl-xL, and cyclin D1 status in stage III and IV larynx cancer patients in a clinical trial. TP53 exons 4 through 9 from 58 tumors were sequenced. Mutations were grouped using three classifications based on their expected function. Each functional group was analyzed for response to induction chemotherapy, time to surgery, survival, HPV status, p16INK4a, Bcl-xl, and cyclin D1 expression. TP53 mutations were found in 22 of 58 (37.9%) patients with advanced larynx cancer, including missense mutations in 13 of 58 (22.4%) patients, nonsense mutations in four of 58 (6.9%), and deletions in five of 58 (8.6%). High-risk HPV was found in 20 of 52 (38.5%) tumors. A classification based on Evolutionary Action score of p53 (EAp53) distinguished missense mutations with high risk for decreased survival from low-risk mutations (P = 0.0315). A model including this TP53 classification, HPV status, cyclin D1, and Bcl-xL staining significantly predicts survival (P = 0.0017). EAp53 functional classification of TP53 mutants and biomarkers predict survival in advanced larynx cancer. NA. Laryngoscope, 126:E292-E299, 2016. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.
Targeting MDM4 as a Novel Therapeutic Approach for Hematologic Malignancies.

PubMed

Cao, Lei; Fan, Lei; Xu, Wei; Li, Jian-Yong

2015-01-01

Mouse double minute 4 (MDM4) as a member of MDM family, is an oncogene emerging as an imperative negative regulator of p53. Tumor suppressor protein p53 plays a crucial role in cell cycle arrest, apoptosis and homeostasis. It has been reported that frequent inactivation of p53 was observed in numerous human cancers including hematologic malignancies. MDM4, the newly discovered modulator of p53 protein, is frequently amplified in various solid tumors such as cutaneous melanoma, retinoblastoma and hematological malignances such as chronic lymphocytic leukemia, acute myeloid leukemia and mantle cell lymphoma. Multiple evidences implicate that over-expression of MDM4 is associated with tumor progression and poor prognosis which can be reversed by knockdown of MDM4 expression or restoration of p53 function, and support the rationale for the design of future MDM4-specific therapeutics. This article discusses and focuses on using MDM4 as a novel biomarker as well as a therapeutic target for hematologic malignancies.
Development of an adenoviral vector with robust expression driven by p53

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bajgelman, Marcio C.; Biotechnology Program, Biomedical Sciences Institute, University of Sao Paulo; Millennium Institute-Gene Therapy Network, Ministry of Science and Technology

2008-02-05

Here we introduce a new adenoviral vector where transgene expression is driven by p53. We first developed a synthetic promoter, referred to as PGTx{beta}, containing a p53-responsive element, a minimal promoter and the first intron of the rabbit {beta}-globin gene. Initial assays using plasmid-based vectors indicated that expression was tightly controlled by p53 and was 5-fold stronger than the constitutive CMV immediate early promoter/enhancer. The adenoviral vector, AdPG, was also shown to offer p53-responsive expression in prostate carcinoma cells LNCaP (wt p53), DU-145 (temperature sensitive mutant of p53) and PC3 (p53-null, but engineered to express temperature-sensitive p53 mutants). AdPG servedmore » as a sensor of p53 activity in LNCaP cells treated with chemotherapeutic agents. Since p53 can be induced by radiotherapy and chemotherapy, this new vector could be further developed for use in combination with conventional therapies to bring about cooperation between the genetic and pharmacologic treatment modalities.« less
S-Nitrosylation of parkin as a novel regulator of p53-mediated neuronal cell death in sporadic Parkinson’s disease

PubMed Central

2013-01-01

Background Mutations in the gene encoding parkin, a neuroprotective protein with dual functions as an E3 ubiquitin ligase and transcriptional repressor of p53, are linked to familial forms of Parkinson’s disease (PD). We hypothesized that oxidative posttranslational modification of parkin by environmental toxins may contribute to sporadic PD. Results We first demonstrated that S-nitrosylation of parkin decreased its activity as a repressor of p53 gene expression, leading to upregulation of p53. Chromatin immunoprecipitation as well as gel-shift assays showed that parkin bound to the p53 promoter, and this binding was inhibited by S-nitrosylation of parkin. Additionally, nitrosative stress induced apoptosis in cells expressing parkin, and this death was, at least in part, dependent upon p53. In primary mesencephalic cultures, pesticide-induced apoptosis was prevented by inhibition of nitric oxide synthase (NOS). In a mouse model of pesticide-induced PD, both S-nitrosylated (SNO-)parkin and p53 protein levels were increased, while administration of a NOS inhibitor mitigated neuronal death in these mice. Moreover, the levels of SNO-parkin and p53 were simultaneously elevated in postmortem human PD brain compared to controls. Conclusions Taken together, our data indicate that S-nitrosylation of parkin, leading to p53-mediated neuronal cell death, contributes to the pathophysiology of sporadic PD. PMID:23985028
MDM4 overexpression contributes to synoviocyte proliferation in patients with rheumatoid arthritis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Nanwei; Wang, Yuji, E-mail: yujiwang@sohu.com; State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433

Research highlights: {yields} Elevated MDM4 mRNA and protein levels in FLS from patients with RA and OA. {yields} Strong MDM4 staining in synovial cells of inflammatory synovium. {yields} MDM4 knockdown increased p53 and p21 levels, and inhibited the proliferation of RA FLS. {yields} MDM4 overexpression increased p53 while decreased p21 levels, and promoted the growth of RA FLS. -- Abstract: Rheumatoid arthritis (RA) is a chronic autoimmune disease with features of inflammatory cell infiltration, synovial cell invasive proliferation, and ultimately, irreversible joint destruction. It has been reported that the p53 pathway is involved in RA pathogenesis. MDM4/MDMX is a majormore » negative regulator of p53. To determine whether MDM4 contributes to RA pathogenesis, MDM4 mRNA and protein expression were assessed in fibroblast-like synoviocytes (FLS) by real-time PCR, western blotting, and in synovial tissues by immunohistochemistry. Furthermore, MDM4 was knocked down and overexpressed by lentivirus-mediated expression, and the proliferative capacity of FLS was determined by MTS assay. We found that cultured FLS from RA and osteoarthritis (OA) patients exhibited higher levels of MDM4 mRNA and protein expression than those from trauma controls. MDM4 protein was highly expressed in the synovial lining and sublining cells from both types of arthritis. Finally, MDM4 knockdown inhibited the proliferation of RA FLS by enhancing functional p53 levels while MDM4 overexpression promoted the growth of RA FLS by inhibiting p53 effects. Taken together, our results suggest that the abundant expression of MDM4 in FLS may contribute to the hyperplasia phenotype of RA synovial tissues.« less
Low expression levels of ATM may substitute for CHEK2 /TP53 mutations predicting resistance towards anthracycline and mitomycin chemotherapy in breast cancer.

PubMed

Knappskog, Stian; Chrisanthar, Ranjan; Løkkevik, Erik; Anker, Gun; Østenstad, Bjørn; Lundgren, Steinar; Risberg, Terje; Mjaaland, Ingvil; Leirvaag, Beryl; Miletic, Hrvoje; Lønning, Per E

2012-03-15

Mutations affecting p53 or its upstream activator Chk2 are associated with resistance to DNA-damaging chemotherapy in breast cancer. ATM (Ataxia Telangiectasia Mutated protein) is the key activator of p53 and Chk2 in response to genotoxic stress. Here, we sought to evaluate ATM's potential role in resistance to chemotherapy. We sequenced ATM and assessed gene expression levels in pre-treatment biopsies from 71 locally advanced breast cancers treated in the neoadjuvant setting with doxorubicin monotherapy or mitomycin combined with 5-fluorouracil. Findings were confirmed in a separate patient cohort treated with epirubicin monotherapy. Each tumor was previously analyzed for CHEK2 and TP53 mutation status. While ATM mutations were not associated with chemo-resistance, low ATM expression levels predicted chemo-resistance among patients with tumors wild-type for TP53 and CHEK2 (P = 0.028). Analyzing the ATM-chk2-p53 cascade, low ATM levels (defined as the lower 5 to 50% percentiles) or mutations inactivating TP53 or CHEK2 robustly predicted anthracycline resistance (P-values varying between 0.001 and 0.027 depending on the percentile used to define "low" ATM levels). These results were confirmed in an independent cohort of 109 patients treated with epirubicin monotherapy. In contrast, ATM-levels were not suppressed in resistant tumors harboring TP53 or CHEK2 mutations (P > 0.5). Our data indicate loss of function of the ATM-Chk2-p53 cascade to be strongly associated with resistance to anthracycline/mitomycin-containing chemotherapy in breast cancer.
Activation of p53 Transcriptional Activity by SMRT: a Histone Deacetylase 3-Independent Function of a Transcriptional Corepressor

PubMed Central

Adikesavan, Anbu Karani; Karmakar, Sudipan; Pardo, Patricia; Wang, Liguo; Liu, Shuang; Li, Wei

2014-01-01

The silencing mediator of retinoic acid and thyroid hormone receptors (SMRT) is an established histone deacetylase 3 (HDAC3)-dependent transcriptional corepressor. Microarray analyses of MCF-7 cells transfected with control or SMRT small interfering RNA revealed SMRT regulation of genes involved in DNA damage responses, and the levels of the DNA damage marker γH2AX as well as poly(ADP-ribose) polymerase cleavage were elevated in SMRT-depleted cells treated with doxorubicin. A number of these genes are established p53 targets. SMRT knockdown decreased the activity of two p53-dependent reporter genes as well as the expression of p53 target genes, such as CDKN1A (which encodes p21). SMRT bound directly to p53 and was recruited to p53 binding sites within the p21 promoter. Depletion of GPS2 and TBL1, components of the SMRT corepressor complex, but not histone deacetylase 3 (HDAC3) decreased p21-luciferase activity. p53 bound to the SMRT deacetylase activation domain (DAD), which mediates HDAC3 binding and activation, and HDAC3 could attenuate p53 binding to the DAD region of SMRT. Moreover, an HDAC3 binding-deficient SMRT DAD mutant coactivated p53 transcriptional activity. Collectively, these data highlight a biological role for SMRT in mediating DNA damage responses and suggest a model where p53 binding to the DAD limits HDAC3 interaction with this coregulator, thereby facilitating SMRT coactivation of p53-dependent gene expression. PMID:24449765

DRAGO (KIAA0247), a new DNA damage-responsive, p53-inducible gene that cooperates with p53 as oncosuppressor. [Corrected].

PubMed

Polato, Federica; Rusconi, Paolo; Zangrossi, Stefano; Morelli, Federica; Boeri, Mattia; Musi, Alberto; Marchini, Sergio; Castiglioni, Vittoria; Scanziani, Eugenio; Torri, Valter; Broggini, Massimo

2014-04-01

p53 influences genomic stability, apoptosis, autophagy, response to stress, and DNA damage. New p53-target genes could elucidate mechanisms through which p53 controls cell integrity and response to damage. DRAGO (drug-activated gene overexpressed, KIAA0247) was characterized by bioinformatics methods as well as by real-time polymerase chain reaction, chromatin immunoprecipitation and luciferase assays, time-lapse microscopy, and cell viability assays. Transgenic mice (94 p53(-/-) and 107 p53(+/-) mice on a C57BL/6J background) were used to assess DRAGO activity in vivo. Survival analyses were performed using Kaplan-Meier curves and the Mantel-Haenszel test. All statistical tests were two-sided. We identified DRAGO as a new p53-responsive gene induced upon treatment with DNA-damaging agents. DRAGO is highly conserved, and its ectopic overexpression resulted in growth suppression and cell death. DRAGO(-/-) mice are viable without macroscopic alterations. However, in p53(-/-) or p53(+/-) mice, the deletion of both DRAGO alleles statistically significantly accelerated tumor development and shortened lifespan compared with p53(-/-) or p53(+/-) mice bearing wild-type DRAGO alleles (p53(-/-), DRAGO(-/-) mice: hazard ratio [HR] = 3.25, 95% confidence interval [CI] = 1.7 to 6.1, P < .001; p53(+/-), DRAGO(-/-) mice: HR = 2.35, 95% CI = 1.3 to 4.0, P < .001; both groups compared with DRAGO(+/+) counterparts). DRAGO mRNA levels were statistically significantly reduced in advanced-stage, compared with early-stage, ovarian tumors, but no mutations were found in several human tumors. We show that DRAGO expression is regulated both at transcriptional-through p53 (and p73) and methylation-dependent control-and post-transcriptional levels by miRNAs. DRAGO represents a new p53-dependent gene highly regulated in human cells and whose expression cooperates with p53 in tumor suppressor functions.
DRAGO (KIAA0247), a New DNA Damage–Responsive, p53-Inducible Gene That Cooperates With p53 as Oncosupprossor

PubMed Central

Polato, Federica; Rusconi, Paolo

2014-01-01

Background p53 influences genomic stability, apoptosis, autophagy, response to stress, and DNA damage. New p53-target genes could elucidate mechanisms through which p53 controls cell integrity and response to damage. Methods DRAGO (drug-activated gene overexpressed, KIAA0247) was characterized by bioinformatics methods as well as by real-time polymerase chain reaction, chromatin immunoprecipitation and luciferase assays, time-lapse microscopy, and cell viability assays. Transgenic mice (94 p53−/− and 107 p53+/− mice on a C57BL/6J background) were used to assess DRAGO activity in vivo. Survival analyses were performed using Kaplan–Meier curves and the Mantel–Haenszel test. All statistical tests were two-sided. Results We identified DRAGO as a new p53-responsive gene induced upon treatment with DNA-damaging agents. DRAGO is highly conserved, and its ectopic overexpression resulted in growth suppression and cell death. DRAGO−/− mice are viable without macroscopic alterations. However, in p53−/− or p53+/− mice, the deletion of both DRAGO alleles statistically significantly accelerated tumor development and shortened lifespan compared with p53−/− or p53+/− mice bearing wild-type DRAGO alleles (p53−/−, DRAGO−/− mice: hazard ratio [HR] = 3.25, 95% confidence interval [CI] = 1.7 to 6.1, P < .001; p53+/−, DRAGO−/− mice: HR = 2.35, 95% CI = 1.3 to 4.0, P < .001; both groups compared with DRAGO+/+ counterparts). DRAGO mRNA levels were statistically significantly reduced in advanced-stage, compared with early-stage, ovarian tumors, but no mutations were found in several human tumors. We show that DRAGO expression is regulated both at transcriptional—through p53 (and p73) and methylation-dependent control—and post-transcriptional levels by miRNAs. Conclusions DRAGO represents a new p53-dependent gene highly regulated in human cells and whose expression cooperates with p53 in tumor suppressor functions. PMID:24652652
Reactivation of wild-type and mutant p53 by tryptophanolderived oxazoloisoindolinone SLMP53-1, a novel anticancer small-molecule

PubMed Central

Soares, Joana; Raimundo, Liliana; Pereira, Nuno A.L.; Monteiro, Ângelo; Gomes, Sara; Bessa, Cláudia; Pereira, Clara; Queiroz, Glória; Bisio, Alessandra; Fernandes, João; Gomes, Célia; Reis, Flávio; Gonçalves, Jorge; Inga, Alberto; Santos, Maria M.M.; Saraiva, Lucília

2016-01-01

Restoration of the p53 pathway, namely by reactivation of mutant (mut) p53, represents a valuable anticancer strategy. Herein, we report the identification of the enantiopure tryptophanol-derived oxazoloisoindolinone SLMP53-1 as a novel reactivator of wild-type (wt) and mut p53, using a yeast-based screening strategy. SLMP53-1 has a p53-dependent anti-proliferative activity in human wt and mut p53R280K-expressing tumor cells. Additionally, SLMP53-1 enhances p53 transcriptional activity and restores wt-like DNA binding ability to mut p53R280K. In wt/mut p53-expressing tumor cells, SLMP53-1 triggers p53 transcription-dependent and mitochondrial apoptotic pathways involving BAX, and wt/mut p53 mitochondrial translocation. SLMP53-1 inhibits the migration of wt/mut p53-expressing tumor cells, and it shows promising p53-dependent synergistic effects with conventional chemotherapeutics. In xenograft mice models, SLMP53-1 inhibits the growth of wt/mut p53-expressing tumors, but not of p53-null tumors, without apparent toxicity. Collectively, besides the potential use of SLMP53-1 as anticancer drug, the tryptophanol-derived oxazoloisoindolinone scaffold represents a promissing starting point for the development of effective p53-reactivating drugs. PMID:26735173
PUMA promotes Bax translocation in FOXO3a-dependent pathway during STS-induced apoptosis

NASA Astrophysics Data System (ADS)

Zhang, Yingjie; Chen, Qun

2009-08-01

PUMA (p53 up-regulated modulator of apoptosis, also called Bbc3) was first identified as a BH3-only Bcl-2 family protein that is transcriptionally up-regulated by p53 and activated upon p53-dependent apoptotic stimuli, such as treatment with DNA-damaging drugs or UV irradiation. Recently studies have been shown that Puma is also up-regulated in response to certain p53-independent apoptotic stimuli, such as growth factor deprivation or treatment with glucocorticoids or STS (staurosporine). However, the molecular mechanisms of PUMA up-regulation and how PUMA functions in response to p53-independent apoptotic stimuli remain poorly understood. In this study, based on real-time single cell analysis, flow cytometry and western blotting technique, we investigated the function of PUMA in living human lung adenocarcinoma cells (ASTC-a-1) after STS treatment. Our results show that FOXO3a was activated by STS stimulation and then translocated from cytosol to nucleus. The expression of PUMA was up-regulated via a FOXO3a-dependent manner after STS treatment, while p53 had little function in this process. Moreover, cell apoptosis and Bax translocation induced by STS were not blocked by Pifithrin-α (p53 inhibitor), which suggested that p53 was not involved in this signaling pathway. Taken together, these results indicate that PUMA promoted Bax translocation in a FOXO3a-dependment pathway during STS-induced apoptosis, while p53 was dispensable in this process.
A High-Throughput Cell-Based Screen Identified a 2-[(E)-2-Phenylvinyl]-8-Quinolinol Core Structure That Activates p53

PubMed Central

Bechill, John; Zhong, Rong; Zhang, Chen; Solomaha, Elena

2016-01-01

p53 function is frequently inhibited in cancer either through mutations or by increased degradation via MDM2 and/or E6AP E3-ubiquitin ligases. Most agents that restore p53 expression act by binding MDM2 or E6AP to prevent p53 degradation. However, fewer compounds directly bind to and activate p53. Here, we identified compounds that shared a core structure that bound p53, caused nuclear localization of p53 and caused cell death. To identify these compounds, we developed a novel cell-based screen to redirect p53 degradation to the Skip-Cullin-F-box (SCF) ubiquitin ligase complex in cells expressing high levels of p53. In a multiplexed assay, we coupled p53 targeted degradation with Rb1 targeted degradation in order to identify compounds that prevented p53 degradation while not inhibiting degradation through the SCF complex or other proteolytic machinery. High-throughput screening identified several leads that shared a common 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that stabilized p53. Surface plasmon resonance analysis indicated that these compounds bound p53 with a KD of 200 ± 52 nM. Furthermore, these compounds increased p53 nuclear localization and transcription of the p53 target genes PUMA, BAX, p21 and FAS in cancer cells. Although p53-null cells had a 2.5±0.5-fold greater viability compared to p53 wild type cells after treatment with core compounds, loss of p53 did not completely rescue cell viability suggesting that compounds may target both p53-dependent and p53-independent pathways to inhibit cell proliferation. Thus, we present a novel, cell-based high-throughput screen to identify a 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that bound to p53 and increased p53 activity in cancer cells. These compounds may serve as anti-neoplastic agents in part by targeting p53 as well as other potential pathways. PMID:27124407
APELA promotes tumour growth and cell migration in ovarian cancer in a p53-dependent manner.

PubMed

Yi, Yuyin; Tsai, Shu-Huei; Cheng, Jung-Chien; Wang, Evan Y; Anglesio, Michael S; Cochrane, Dawn R; Fuller, Megan; Gibb, Ewan A; Wei, Wei; Huntsman, David G; Karsan, Aly; Hoodless, Pamela A

2017-12-01

APELA is a small, secreted peptide that can function as a ligand for the G-protein coupled receptor, Apelin Receptor (APLNR, APJ). APELA plays an essential role in endoderm differentiation and cardiac development during embryogenesis. We investigated whether APELA exerts any functions in cancer progression. The Cancer Genome Atlas (TCGA) RNA sequencing datasets, microarray from an OCCC mouse model, and RNA isolated from fresh frozen and FFPE patient tissue were used to assess APELA expression. APELA knockout ovarian clear cell carcinoma (OCCC) cell lines were generated using CRISPR/Cas9. APELA was expressed in various ovarian cancer histotypes and was especially elevated in OCCC. Disruption of APELA expression in OCCC cell lines suppressed cell growth and migration, and altered cell-cycle progression. Moreover, addition of human recombinant APELA peptide to the OCCC cell line OVISE promoted cell growth and migration. Interestingly, OVISE cells do not express APLNR, suggesting that APELA can function through an APLNR-independent pathway. Furthermore, APELA affected cell growth and cell cycle progression in a p53-dependent manner. In addition, APELA knockdown induced p53 expression in cancer cell lines. Our findings uncover a potential oncogenic role for APELA in promoting ovarian tumour progression and provide a possible therapeutic strategy in ovarian cancer by targeting APELA. Copyright © 2017 Elsevier Inc. All rights reserved.
The homeoprotein DLX3 and tumor suppressor p53 co-regulate cell cycle progression and squamous tumor growth.

PubMed

Palazzo, E; Kellett, M; Cataisson, C; Gormley, A; Bible, P W; Pietroni, V; Radoja, N; Hwang, J; Blumenberg, M; Yuspa, S H; Morasso, M I

2016-06-16

Epidermal homeostasis depends on the coordinated control of keratinocyte cell cycle. Differentiation and the alteration of this balance can result in neoplastic development. Here we report on a novel DLX3-dependent network that constrains epidermal hyperplasia and squamous tumorigenesis. By integrating genetic and transcriptomic approaches, we demonstrate that DLX3 operates through a p53-regulated network. DLX3 and p53 physically interact on the p21 promoter to enhance p21 expression. Elevating DLX3 in keratinocytes produces a G1-S blockade associated with p53 signature transcriptional profiles. In contrast, DLX3 loss promotes a mitogenic phenotype associated with constitutive activation of ERK. DLX3 expression is lost in human skin cancers and is extinguished during progression of experimentally induced mouse squamous cell carcinoma (SCC). Reinstatement of DLX3 function is sufficient to attenuate the migration of SCC cells, leading to decreased wound closure. Our data establish the DLX3-p53 interplay as a major regulatory axis in epidermal differentiation and suggest that DLX3 is a modulator of skin carcinogenesis.
The homeoprotein DLX3 and tumor suppressor p53 co-regulate cell cycle progression and squamous tumor growth

PubMed Central

Palazzo, Elisabetta; Kellett, Meghan; Cataisson, Christophe; Gormley, Anna; Bible, Paul W.; Pietroni, Valentina; Radoja, Nadezda; Hwang, Joonsung; Blumenberg, Miroslav; Yuspa, Stuart H.; Morasso, Maria

2015-01-01

Epidermal homeostasis depends on the coordinated control of keratinocyte cell cycle. Differentiation and the alteration of this balance can result in neoplastic development. Here we report on a novel DLX3-dependent network that constrains epidermal hyperplasia and squamous tumorigenesis. By integrating genetic and transcriptomic approaches, we demonstrate that DLX3 operates through a p53-regulated network. DLX3 and p53 physically interact on the p21 promoter to enhance p21 expression. Elevating DLX3 in keratinocytes produces a G1-S blockade associated with p53 signature transcriptional profiles. In contrast, DLX3 loss promotes a mitogenic phenotype associated with constitutive activation of ERK. DLX3 expression is lost in human skin cancers and is extinquished during progression of experimentally induced mouse squamous cell carcinoma (SCC). Reinstatement of DLX3 function is sufficient to attenuate the migration of SCC cells, leading to decreased wound closure. Our data establish the DLX3-p53 interplay as a major regulatory axis in epidermal differentiation and suggest that DLX3 is a modulator of skin carcinogenesis. PMID:26522723
The maternal genes Ci-p53/p73-a and Ci-p53/p73-b regulate zygotic ZicL expression and notochord differentiation in Ciona intestinalis embryos.

PubMed

Noda, Takeshi

2011-12-01

I isolated a Ciona intestinalis homolog of p53, Ci-p53/p73-a, in a microarray screen of rapidly degraded maternal mRNA by comparing the transcriptomes of unfertilized eggs and 32-cell stage embryos. Higher expression of the gene in eggs and lower expression in later embryonic stages were confirmed by whole-mount in situ hybridization (WISH) and quantitative reverse transcription-PCR (qRT-PCR); expression was ubiquitous in eggs and early embryos. Knockdown of Ci-p53/p73-a by injection of antisense morpholino oligonucleotides (MOs) severely perturbed gastrulation cell movements and expression of notochord marker genes. A key regulator of notochord differentiation in Ciona embryos is Brachyury (Ci-Bra), which is directly activated by a zic-like gene (Ci-ZicL). The expression of Ci-ZicL and Ci-Bra in A-line notochord precursors was downregulated in Ci-p53/p73-a knockdown embryos. Maternal expression of Ci-p53/p73-b, a homolog of Ci-p53/p73-a, was also detected. In Ci-p53/p73-b knockdown embryos, gastrulation cell movements, expression of Ci-ZicL and Ci-Bra in A-line notochord precursors, and expression of notochord marker gene at later stages were perturbed. The upstream region of Ci-ZicL contains putative p53-binding sites. Cis-regulatory analysis of Ci-ZicL showed that these sites are involved in expression of Ci-ZicL in A-line notochord precursors at the 32-cell and early gastrula stages. These results suggest that p53 genes are maternal factors that play a crucial role in A-line notochord differentiation in C. intestinalis embryos by regulating Ci-ZicL expression. Copyright © 2011 Elsevier Inc. All rights reserved.
Genomic analysis of wig-1 pathways.

PubMed

Sedaghat, Yalda; Mazur, Curt; Sabripour, Mahyar; Hung, Gene; Monia, Brett P

2012-01-01

Wig-1 is a transcription factor regulated by p53 that can interact with hnRNP A2/B1, RNA Helicase A, and dsRNAs, which plays an important role in RNA and protein stabilization. in vitro studies have shown that wig-1 binds p53 mRNA and stabilizes it by protecting it from deadenylation. Furthermore, p53 has been implicated as a causal factor in neurodegenerative diseases based in part on its selective regulatory function on gene expression, including genes which, in turn, also possess regulatory functions on gene expression. In this study we focused on the wig-1 transcription factor as a downstream p53 regulated gene and characterized the effects of wig-1 down regulation on gene expression in mouse liver and brain. Antisense oligonucleotides (ASOs) were identified that specifically target mouse wig-1 mRNA and produce a dose-dependent reduction in wig-1 mRNA levels in cell culture. These wig-1 ASOs produced marked reductions in wig-1 levels in liver following intraperitoneal administration and in brain tissue following ASO administration through a single striatal bolus injection in FVB and BACHD mice. Wig-1 suppression was well tolerated and resulted in the reduction of mutant Htt protein levels in BACHD mouse brain but had no effect on normal Htt protein levels nor p53 mRNA or protein levels. Expression microarray analysis was employed to determine the effects of wig-1 suppression on genome-wide expression in mouse liver and brain. Reduction of wig-1 caused both down regulation and up regulation of several genes, and a number of wig-1 regulated genes were identified that potentially links wig-1 various signaling pathways and diseases. Antisense oligonucleotides can effectively reduce wig-1 levels in mouse liver and brain, which results in specific changes in gene expression for pathways relevant to both the nervous system and cancer.
Genomic Analysis of wig-1 Pathways

PubMed Central

Sedaghat, Yalda; Mazur, Curt; Sabripour, Mahyar; Hung, Gene; Monia, Brett P.

2012-01-01

Background Wig-1 is a transcription factor regulated by p53 that can interact with hnRNP A2/B1, RNA Helicase A, and dsRNAs, which plays an important role in RNA and protein stabilization. in vitro studies have shown that wig-1 binds p53 mRNA and stabilizes it by protecting it from deadenylation. Furthermore, p53 has been implicated as a causal factor in neurodegenerative diseases based in part on its selective regulatory function on gene expression, including genes which, in turn, also possess regulatory functions on gene expression. In this study we focused on the wig-1 transcription factor as a downstream p53 regulated gene and characterized the effects of wig-1 down regulation on gene expression in mouse liver and brain. Methods and Results Antisense oligonucleotides (ASOs) were identified that specifically target mouse wig-1 mRNA and produce a dose-dependent reduction in wig-1 mRNA levels in cell culture. These wig-1 ASOs produced marked reductions in wig-1 levels in liver following intraperitoneal administration and in brain tissue following ASO administration through a single striatal bolus injection in FVB and BACHD mice. Wig-1 suppression was well tolerated and resulted in the reduction of mutant Htt protein levels in BACHD mouse brain but had no effect on normal Htt protein levels nor p53 mRNA or protein levels. Expression microarray analysis was employed to determine the effects of wig-1 suppression on genome-wide expression in mouse liver and brain. Reduction of wig-1 caused both down regulation and up regulation of several genes, and a number of wig-1 regulated genes were identified that potentially links wig-1 various signaling pathways and diseases. Conclusion Antisense oligonucleotides can effectively reduce wig-1 levels in mouse liver and brain, which results in specific changes in gene expression for pathways relevant to both the nervous system and cancer. PMID:22347364
Prognostic significance of p53 immunohistochemical expression in adenoid cystic carcinoma of the salivary glands: a meta-analysis

PubMed Central

Zheng, Chuanming; Wang, Jiafeng; Ge, Minghua

2017-01-01

Adenoid cystic carcinoma of salivary glands is a rare adenocarcinoma and has been placed in “high-risk” category as poor long-term prognosis. The purpose of this study was to investigate p53 protein expression in adenoid cystic carcinoma of salivary glands and its correlation with clinicopathological parameters and prognosis. Literatures were searched from PubMed, Embase, Cochrane Library and Web of Science, which investigated the relationships between p53 expression and pathological type, clinical stage, local recurrence, metastasis, nerve infiltration and overall survival. A total of 1,608 patients from 36 studies were included in the analysis. The results showed that p53-postive expression rate was 49% in adenoid cystic carcinoma of salivary glands (OR=10.34, 95%CI: 4.93-21.71, P < 0.0001). The p53-postive expression was closely related to tumor types (OR=0.30, 95%CI: 0.14-0.65, P < 0.0001). The tumor with solid histological subtype had a strong positive correlation with p53 expression. The combined analysis revealed that the p53-positive expression rate among patients in T1and T2 stage was 41.4%, compared to 53.2% among those in T3 and T4 stage. However, there was no significant correlation between tumor stage and p53 expression (OR=0.47, 95% CI: 0.17-1.29, P = 0.14). Besides, compared to patients with p53-negative expression, those with p53-positive expression had a greater chance of developing metastasis, local recurrence and nerve infiltration as well as poorer 5-year overall survival (P < 0.01). In conclusion, the p53 expression is related to the survival of adenoid cystic carcinoma of salivary glands. It can be considered as the auxiliary detection index in treatment and prognosis of adenoid cystic carcinoma of salivary glands. PMID:28206977
Prognostic significance of p53 immunohistochemical expression in adenoid cystic carcinoma of the salivary glands: a meta-analysis.

PubMed

Li, Qinglin; Huang, Ping; Zheng, Chuanming; Wang, Jiafeng; Ge, Minghua

2017-04-25

Adenoid cystic carcinoma of salivary glands is a rare adenocarcinoma and has been placed in "high-risk" category as poor long-term prognosis. The purpose of this study was to investigate p53 protein expression in adenoid cystic carcinoma of salivary glands and its correlation with clinicopathological parameters and prognosis. Literatures were searched from PubMed, Embase, Cochrane Library and Web of Science, which investigated the relationships between p53 expression and pathological type, clinical stage, local recurrence, metastasis, nerve infiltration and overall survival. A total of 1,608 patients from 36 studies were included in the analysis. The results showed that p53-postive expression rate was 49% in adenoid cystic carcinoma of salivary glands (OR=10.34, 95%CI: 4.93-21.71, P < 0.0001). The p53-postive expression was closely related to tumor types (OR=0.30, 95%CI: 0.14-0.65, P < 0.0001). The tumor with solid histological subtype had a strong positive correlation with p53 expression. The combined analysis revealed that the p53-positive expression rate among patients in T1and T2 stage was 41.4%, compared to 53.2% among those in T3 and T4 stage. However, there was no significant correlation between tumor stage and p53 expression (OR=0.47, 95% CI: 0.17-1.29, P = 0.14). Besides, compared to patients with p53-negative expression, those with p53-positive expression had a greater chance of developing metastasis, local recurrence and nerve infiltration as well as poorer 5-year overall survival (P < 0.01).In conclusion, the p53 expression is related to the survival of adenoid cystic carcinoma of salivary glands. It can be considered as the auxiliary detection index in treatment and prognosis of adenoid cystic carcinoma of salivary glands.
Nuclear inclusion bodies of mutant and wild-type p53 in cancer: a hallmark of p53 inactivation and proteostasis remodelling by p53 aggregation.

PubMed

De Smet, Frederik; Saiz Rubio, Mirian; Hompes, Daphne; Naus, Evelyne; De Baets, Greet; Langenberg, Tobias; Hipp, Mark S; Houben, Bert; Claes, Filip; Charbonneau, Sarah; Delgado Blanco, Javier; Plaisance, Stephane; Ramkissoon, Shakti; Ramkissoon, Lori; Simons, Colinda; van den Brandt, Piet; Weijenberg, Matty; Van England, Manon; Lambrechts, Sandrina; Amant, Frederic; D'Hoore, André; Ligon, Keith L; Sagaert, Xavier; Schymkowitz, Joost; Rousseau, Frederic

2017-05-01

Although p53 protein aggregates have been observed in cancer cell lines and tumour tissue, their impact in cancer remains largely unknown. Here, we extensively screened for p53 aggregation phenotypes in tumour biopsies, and identified nuclear inclusion bodies (nIBs) of transcriptionally inactive mutant or wild-type p53 as the most frequent aggregation-like phenotype across six different cancer types. p53-positive nIBs co-stained with nuclear aggregation markers, and shared molecular hallmarks of nIBs commonly found in neurodegenerative disorders. In cell culture, tumour-associated stress was a strong inducer of p53 aggregation and nIB formation. This was most prominent for mutant p53, but could also be observed in wild-type p53 cell lines, for which nIB formation correlated with the loss of p53's transcriptional activity. Importantly, protein aggregation also fuelled the dysregulation of the proteostasis network in the tumour cell by inducing a hyperactivated, oncogenic heat-shock response, to which tumours are commonly addicted, and by overloading the proteasomal degradation system, an observation that was most pronounced for structurally destabilized mutant p53. Patients showing tumours with p53-positive nIBs suffered from a poor clinical outcome, similar to those with loss of p53 expression, and tumour biopsies showed a differential proteostatic expression profile associated with p53-positive nIBs. p53-positive nIBs therefore highlight a malignant state of the tumour that results from the interplay between (1) the functional inactivation of p53 through mutation and/or aggregation, and (2) microenvironmental stress, a combination that catalyses proteostatic dysregulation. This study highlights several unexpected clinical, biological and therapeutically unexplored parallels between cancer and neurodegeneration. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The p53-Reactivating Small Molecule RITA Induces Senescence in Head and Neck Cancer Cells

PubMed Central

Chuang, Hui-Ching; Yang, Liang Peng; Fitzgerald, Alison L.; Osman, Abdullah; Woo, Sang Hyeok; Myers, Jeffrey N.; Skinner, Heath D.

2014-01-01

TP53 is the most commonly mutated gene in head and neck cancer (HNSCC), with mutations being associated with resistance to conventional therapy. Restoring normal p53 function has previously been investigated via the use of RITA (reactivation of p53 and induction of tumor cell apoptosis), a small molecule that induces a conformational change in p53, leading to activation of its downstream targets. In the current study we found that RITA indeed exerts significant effects in HNSCC cells. However, in this model, we found that a significant outcome of RITA treatment was accelerated senescence. RITA-induced senescence in a variety of p53 backgrounds, including p53 null cells. Also, inhibition of p53 expression did not appear to significantly inhibit RITA-induced senescence. Thus, this phenomenon appears to be partially p53-independent. Additionally, RITA-induced senescence appears to be partially mediated by activation of the DNA damage response and SIRT1 (Silent information regulator T1) inhibition, with a synergistic effect seen by combining either ionizing radiation or SIRT1 inhibition with RITA treatment. These data point toward a novel mechanism of RITA function as well as hint to its possible therapeutic benefit in HNSCC. PMID:25119136
Expression of p53, Bcl-2, VEGF, Ki67 and PCNA and prognostic significance in hepatocellular carcinoma.

PubMed

Stroescu, Cezar; Dragnea, Adrian; Ivanov, Bogdan; Pechianu, Catalin; Herlea, Vlad; Sgarbura, Olivia; Popescu, Andra; Popescu, Irinel

2008-12-01

Hepatocellular carcinoma is one of the most common malignant tumors that carry a poor prognosis. To improve the long-term outlook for HCC, an accurate prognosis is important. To study the immunohistochemical expressions of p53, Ki67, Bcl-2, VEGF and PCNA and their potential role as prognostic factors in patients with radical resection of hepatocellular carcinoma. Forty-seven formalin-fixed paraffin-embedded tumor samples from patients with HCC receiving liver resection were investigated immunohistochemically for the expression of cellular proliferation markers PCNA, Ki67, p53, Bcl-2 and VEGF and their correlation with tumor characteristics and survival time after resection. p53 was expressed in a higher percentage (85.7 vs. 42.1%) in undifferentiated histological tumor grades (Edmondson Steiner G3/G4 vs. G1/G2). Patients with p53 accumulating tumors showed a worse survival than patients with p53 non-accumulating tumors (median 9.5 vs. 16.5 months). Over-expression of VEGF was found in 38.3% of all HCCs. VEGF expression was significantly correlated with p53 expression and recurrence rates. The results showed that the labeling index of PCNA and expression of p53 are correlated. The high labeling index of PCNA or over-expression of p53 resulted in high risk of tumor recurrence, more aggressive growth and poor survival. High labeling index of PCNA, p53 nuclear accumulation and VEGF high expression are associated with poor survival in patients with HCC.
Genome-wide identification of novel expression signatures reveal distinct patterns and prevalence of binding motifs for p53, nuclear factor-κB and other signal transcription factors in head and neck squamous cell carcinoma

PubMed Central

Yan, Bin; Yang, Xinping; Lee, Tin-Lap; Friedman, Jay; Tang, Jun; Van Waes, Carter; Chen, Zhong

2007-01-01

Background Differentially expressed gene profiles have previously been observed among pathologically defined cancers by microarray technologies, including head and neck squamous cell carcinomas (HNSCCs). However, the molecular expression signatures and transcriptional regulatory controls that underlie the heterogeneity in HNSCCs are not well defined. Results Genome-wide cDNA microarray profiling of ten HNSCC cell lines revealed novel gene expression signatures that distinguished cancer cell subsets associated with p53 status. Three major clusters of over-expressed genes (A to C) were defined through hierarchical clustering, Gene Ontology, and statistical modeling. The promoters of genes in these clusters exhibited different patterns and prevalence of transcription factor binding sites for p53, nuclear factor-κB (NF-κB), activator protein (AP)-1, signal transducer and activator of transcription (STAT)3 and early growth response (EGR)1, as compared with the frequency in vertebrate promoters. Cluster A genes involved in chromatin structure and function exhibited enrichment for p53 and decreased AP-1 binding sites, whereas clusters B and C, containing cytokine and antiapoptotic genes, exhibited a significant increase in prevalence of NF-κB binding sites. An increase in STAT3 and EGR1 binding sites was distributed among the over-expressed clusters. Novel regulatory modules containing p53 or NF-κB concomitant with other transcription factor binding motifs were identified, and experimental data supported the predicted transcriptional regulation and binding activity. Conclusion The transcription factors p53, NF-κB, and AP-1 may be important determinants of the heterogeneous pattern of gene expression, whereas STAT3 and EGR1 may broadly enhance gene expression in HNSCCs. Defining these novel gene signatures and regulatory mechanisms will be important for establishing new molecular classifications and subtyping, which in turn will promote development of targeted therapeutics for HNSCC. PMID:17498291
Increased gene expression noise in human cancers is correlated with low p53 and immune activities as well as late stage cancer.

PubMed

Han, Rongfei; Huang, Guanqun; Wang, Yejun; Xu, Yafei; Hu, Yueming; Jiang, Wenqi; Wang, Tianfu; Xiao, Tian; Zheng, Duo

2016-11-01

Gene expression in metazoans is delicately organized. As genetic information transmits from DNA to RNA and protein, expression noise is inevitably generated. Recent studies begin to unveil the mechanisms of gene expression noise control, but the changes of gene expression precision in pathologic conditions like cancers are unknown. Here we analyzed the transcriptomic data of human breast, liver, lung and colon cancers, and found that the expression noise of more than 74.9% genes was increased in cancer tissues as compared to adjacent normal tissues. This suggested that gene expression precision controlling collapsed during cancer development. A set of 269 genes with noise increased more than 2-fold were identified across different cancer types. These genes were involved in cell adhesion, catalytic and metabolic functions, implying the vulnerability of deregulation of these processes in cancers. We also observed a tendency of increased expression noise in patients with low p53 and immune activity in breast, liver and lung caners but not in colon cancers, which indicated the contributions of p53 signaling and host immune surveillance to gene expression noise in cancers. Moreover, more than 53.7% genes had increased noise in patients with late stage than early stage cancers, suggesting that gene expression precision was associated with cancer outcome. Together, these results provided genomic scale explorations of gene expression noise control in human cancers.
The expanding regulatory universe of p53 in gastrointestinal cancer.

PubMed

Fesler, Andrew; Zhang, Ning; Ju, Jingfang

2016-01-01

Tumor suppresser gene TP53 is one of the most frequently deleted or mutated genes in gastrointestinal cancers. As a transcription factor, p53 regulates a number of important protein coding genes to control cell cycle, cell death, DNA damage/repair, stemness, differentiation and other key cellular functions. In addition, p53 is also able to activate the expression of a number of small non-coding microRNAs (miRNAs) through direct binding to the promoter region of these miRNAs. Many miRNAs have been identified to be potential tumor suppressors by regulating key effecter target mRNAs. Our understanding of the regulatory network of p53 has recently expanded to include long non-coding RNAs (lncRNAs). Like miRNA, lncRNAs have been found to play important roles in cancer biology. With our increased understanding of the important functions of these non-coding RNAs and their relationship with p53, we are gaining exciting new insights into the biology and function of cells in response to various growth environment changes. In this review we summarize the current understanding of the ever expanding involvement of non-coding RNAs in the p53 regulatory network and its implications for our understanding of gastrointestinal cancer.
Functional repair of p53 mutation in colorectal cancer cells using trans-splicing.

PubMed

He, Xingxing; Liao, Jiazhi; Liu, Fang; Yan, Junwei; Yan, Jingjun; Shang, Haitao; Dou, Qian; Chang, Ying; Lin, Jusheng; Song, Yuhu

2015-02-10

Mutation in the p53 gene is arguably the most frequent type of gene-specific alterations in human cancers. Current p53-based gene therapy contains the administration of wt-p53 or the suppression of mutant p53 expression in p53-defective cancer cells. . We hypothesized that trans-splicing could be exploited as a tool for the correction of mutant p53 transcripts in p53-mutated human colorectal cancer (CRC) cells. In this study, the plasmids encoding p53 pre-trans-splicing molecules (PTM) were transfected into human CRC cells carrying p53 mutation. The plasmids carrying p53-PTM repaired mutant p53 transcripts in p53-mutated CRC cells, which resulted in a reduction in mutant p53 transcripts and an induction of wt-p53 simultaneously. Intratumoral administration of adenovirus vectors carrying p53 trans-splicing cassettes suppressed the growth of tumor xenografts. Repair of mutant p53 transcripts by trans-splicing induced cell-cycle arrest and apoptosis in p53-defective colorectal cancer cells in vitro and in vivo. In conclusion, the present study demonstrated for the first time that trans-splicing was exploited as a strategy for the repair of mutant p53 transcripts, which revealed that trans-splicing would be developed as a new therapeutic approach for human colorectal cancers carrying p53 mutation.

Low-level overexpression of p53 promotes warfarin-induced calcification of porcine aortic valve interstitial cells by activating Slug gene transcription.

PubMed

Gao, Li; Ji, Yue; Lu, Yan; Qiu, Ming; Shen, Yejiao; Wang, Yaqing; Kong, Xiangqing; Shao, Yongfeng; Sheng, Yanhui; Sun, Wei

2018-03-09

The most frequently used oral anti-coagulant warfarin has been implicated in inducing calcification of aortic valve interstitial cells (AVICs), whereas the mechanism is not fully understood. The low-level activation of p53 is found to be involved in osteogenic transdifferentiation and calcification of AVICs. Whether p53 participates in warfarin-induced AVIC calcification remains unknown. In this study, we investigated the role of low-level p53 overexpression in warfarin-induced porcine AVIC (pAVIC) calcification. Immunostaining, quantitative PCR, and Western blotting revealed that p53 was expressed in human and pAVICs and that p53 expression was slightly increased in calcific human aortic valves compared with non-calcific valves. Terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling staining indicated that apoptosis slightly increased in calcific aortic valves than in non-calcific valves. Warfarin treatment led to a low-level increase of p53 mRNA and protein in both pAVICs and mouse aortic valves. Low-level overexpression of p53 in pAVICs via an adenovirus vector did not affect pAVIC apoptosis but promoted warfarin-induced calcium deposition and expression of osteogenic markers. shRNA-mediated p53 knockdown attenuated the pAVIC calcium deposition and osteogenic marker expression. Moreover, ChIP and luciferase assays showed that p53 was recruited to the slug promoter and activated slug expression in calcific pAVICs. Of note, overexpression of Slug increased osteogenic marker Runx2 expression, but not pAVIC calcium deposition, and Slug knockdown attenuated pAVIC calcification and p53-mediated pAVIC calcium deposition and expression of osteogenic markers. In conclusion, we found that p53 plays an important role in warfarin induced pAVIC calcification, and increased slug transcription by p53 is required for p53-mediated pAVIC calcification. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.
[Expression of Ki-67 and P53 protein in oral squamous cell carcinoma and its clinical significance].

PubMed

He, Wei; Xiao, Yan; Chen, Wei-min

2015-04-01

To investigate the clinical and pathological features and its relationship with the expression of Ki-67 and p53 protein in oral squamous cell carcinoma. Immunohistochemical SP staining method was used to quantify the protein expression levels of Ki-67 and p53 protein in 10 cases of normal oral mucosa, 16 cases of oral leukoplakia (OLK) tissue, and 48 cases of oral squamous cell carcinoma. The relationship of the expression of Ki-67 and p53 protein to clinical and pathological data was analyzed, and SPSS17.0 software package was used for statistical analysis. The positive expression rate of Ki-67 protein in normal oral mucosa, oral leukoplakia and oral squamous cell carcinoma was 30%, 56.3% and 79.2%, respectively; The positive expression rate of p53 was 0%, 43.8%, and 70.8%, respectively; Ki-67 and p53 expression had significant difference among normal oral mucosa, oral leukoplakia and oral squamous cell carcinoma (P<0.05); The expression of Ki-67 protein was significantly elevated with tumor stage, differentiation and cervical lymph node metastasis (P<0.05); The expression of p53 protein was significantly related to the degree of tumor differentiation (P<0.05); The expression of Ki-67 and p53 was positively correlated in oral squamous cell carcinoma (P<0.05). The high expression of Ki-67 and p53 protein in oral squamous cell carcinoma tissues may play an important role in the development of oral squamous cell carcinoma.
Forced Expression of Heat Shock Protein 27 (Hsp27) Reverses P-Glycoprotein (ABCB1)-mediated Drug Efflux and MDR1 Gene Expression in Adriamycin-resistant Human Breast Cancer Cells*

PubMed Central

Kanagasabai, Ragu; Krishnamurthy, Karthikeyan; Druhan, Lawrence J.; Ilangovan, Govindasamy

2011-01-01

Mutant p53 accumulation has been shown to induce the multidrug resistance gene (MDR1) and ATP binding cassette (ABC)-based drug efflux in human breast cancer cells. In the present work, we have found that transcriptional activation of the oxidative stress-responsive heat shock factor 1 (HSF-1) and expression of heat shock proteins, including Hsp27, which is normally known to augment proteasomal p53 degradation, are inhibited in Adriamycin (doxorubicin)-resistant MCF-7 cells (MCF-7/adr). Such an endogenous inhibition of HSF-1 and Hsp27 in turn results in p53 mutation with gain of function in its transcriptional activity and accumulation in MCF-7/adr. Also, lack of HSF-1 enhances nuclear factor κB (NF-κB) DNA binding activity together with mutant p53 and induces MDR1 gene and P-glycoprotein (P-gp, ABCB1), resulting in a multidrug-resistant phenotype. Ectopic expression of Hsp27, however, significantly depleted both mutant p53 and NF-κB (p65), reversed the drug resistance by inhibiting MDR1/P-gp expression in MCF-7/adr cells, and induced cell death by increased G2/M population and apoptosis. We conclude from these results that HSF-1 inhibition and depletion of Hsp27 is a trigger, at least in part, for the accumulation of transcriptionally active mutant p53, which can either directly or NF-κB-dependently induce an MDR1/P-gp phenotype in MCF-7 cells. Upon Hsp27 overexpression, this pathway is abrogated, and the acquired multidrug resistance is significantly abolished so that MCF-7/adr cells are sensitized to Dox. Thus, clinical alteration in Hsp27 or NF-κB level will be a potential approach to circumvent drug resistance in breast cancer. PMID:21784846
Forced expression of heat shock protein 27 (Hsp27) reverses P-glycoprotein (ABCB1)-mediated drug efflux and MDR1 gene expression in Adriamycin-resistant human breast cancer cells.

PubMed

Kanagasabai, Ragu; Krishnamurthy, Karthikeyan; Druhan, Lawrence J; Ilangovan, Govindasamy

2011-09-23

Mutant p53 accumulation has been shown to induce the multidrug resistance gene (MDR1) and ATP binding cassette (ABC)-based drug efflux in human breast cancer cells. In the present work, we have found that transcriptional activation of the oxidative stress-responsive heat shock factor 1 (HSF-1) and expression of heat shock proteins, including Hsp27, which is normally known to augment proteasomal p53 degradation, are inhibited in Adriamycin (doxorubicin)-resistant MCF-7 cells (MCF-7/adr). Such an endogenous inhibition of HSF-1 and Hsp27 in turn results in p53 mutation with gain of function in its transcriptional activity and accumulation in MCF-7/adr. Also, lack of HSF-1 enhances nuclear factor κB (NF-κB) DNA binding activity together with mutant p53 and induces MDR1 gene and P-glycoprotein (P-gp, ABCB1), resulting in a multidrug-resistant phenotype. Ectopic expression of Hsp27, however, significantly depleted both mutant p53 and NF-κB (p65), reversed the drug resistance by inhibiting MDR1/P-gp expression in MCF-7/adr cells, and induced cell death by increased G(2)/M population and apoptosis. We conclude from these results that HSF-1 inhibition and depletion of Hsp27 is a trigger, at least in part, for the accumulation of transcriptionally active mutant p53, which can either directly or NF-κB-dependently induce an MDR1/P-gp phenotype in MCF-7 cells. Upon Hsp27 overexpression, this pathway is abrogated, and the acquired multidrug resistance is significantly abolished so that MCF-7/adr cells are sensitized to Dox. Thus, clinical alteration in Hsp27 or NF-κB level will be a potential approach to circumvent drug resistance in breast cancer.
Myeloid leukemia factor 1 regulates p53 by suppressing COP1 via COP9 signalosome subunit 3

PubMed Central

Yoneda-Kato, Noriko; Tomoda, Kiichiro; Umehara, Mari; Arata, Yukinobu; Kato, Jun-ya

2005-01-01

Myeloid leukemia factor 1 (MLF1) was first identified as the leukemic fusion protein NPM-MLF1 generated by the t(3;5)(q25.1;q34) chromosomal translocation. Although MLF1 expresses normally in a variety of tissues including hematopoietic stem cells and the overexpression of MLF1 correlates with malignant transformation in human cancer, little is known about how MLF1 is involved in the regulation of cell growth. Here we show that MLF1 is a negative regulator of cell cycle progression functioning upstream of the tumor suppressor p53. MLF1 induces p53-dependent cell cycle arrest in murine embryonic fibroblasts. This action requires a novel binding partner, subunit 3 of the COP9 signalosome (CSN3). A reduction in the level of CSN3 protein with small interfering RNA abrogated MLF1-induced G1 arrest and impaired the activation of p53 by genotoxic stress. Furthermore, ectopic MLF1 expression and CSN3 knockdown inversely affect the endogenous level of COP1, a ubiquitin ligase for p53. Exogenous expression of COP1 overcomes MLF1-induced growth arrest. These results indicate that MLF1 is a critical regulator of p53 and suggest its involvement in leukemogenesis through a novel CSN3–COP1 pathway. PMID:15861129
The UbL-UBA Ubiquilin4 protein functions as a tumor suppressor in gastric cancer by p53-dependent and p53-independent regulation of p21.

PubMed

Huang, Shengkai; Li, Yan; Yuan, Xinghua; Zhao, Mei; Wang, Jia; Li, You; Li, Yuan; Lin, Hong; Zhang, Qiao; Wang, Wenjie; Li, Dongdong; Dong, Xin; Li, Lanfen; Liu, Min; Huang, Weiyan; Huang, Changzhi

2018-06-13

Ubiquilin4 (Ubqln4), a member of the UbL-UBA protein family, serves as an adaptor in the degradation of specific substrates via the proteasomal pathway. However, the biological function of Ubqln4 remains largely unknown, especially in cancer. Here, we reported that Ubqln4 was downregulated in gastric cancer tissues and functioned as a tumor suppressor by inhibiting gastric cancer cell proliferation in vivo and in vitro. Overexpression of Ubqln4-induced cellular senescence and G1-S cell cycle arrest in gastric cancer cells and activated the p53/p21 axis. Moreover, Ubqln4 regulated p21 through both p53-dependent and p53-independent manners. Ubqln4 interacted with RNF114, an E3 ubiquitin ligase of p21, and negatively regulated its expression level, which in turn stabilized p21 by attenuating proteasomal degradation of p21. These effects of Ubqln4 were partly abrogated in gastric cancer cells upon silencing of p21. Our findings not only establish the anti-tumor potential of Ubqln4 in gastric cancer but also reveal a role for Ubqln4 in regulation of the cell cycle and cellular senescence via stabilizing p21.
Mutant p53 proteins counteract autophagic mechanism sensitizing cancer cells to mTOR inhibition.

PubMed

Cordani, Marco; Oppici, Elisa; Dando, Ilaria; Butturini, Elena; Dalla Pozza, Elisa; Nadal-Serrano, Mercedes; Oliver, Jordi; Roca, Pilar; Mariotto, Sofia; Cellini, Barbara; Blandino, Giovanni; Palmieri, Marta; Di Agostino, Silvia; Donadelli, Massimo

2016-08-01

Mutations in TP53 gene play a pivotal role in tumorigenesis and cancer development. Here, we report that gain-of-function mutant p53 proteins inhibit the autophagic pathway favoring antiapoptotic effects as well as proliferation of pancreas and breast cancer cells. We found that mutant p53 significantly counteracts the formation of autophagic vesicles and their fusion with lysosomes throughout the repression of some key autophagy-related proteins and enzymes as BECN1 (and P-BECN1), DRAM1, ATG12, SESN1/2 and P-AMPK with the concomitant stimulation of mTOR signaling. As a paradigm of this mechanism, we show that atg12 gene repression was mediated by the recruitment of the p50 NF-κB/mutant p53 protein complex onto the atg12 promoter. Either mutant p53 or p50 NF-κB depletion downregulates atg12 gene expression. We further correlated the low expression levels of autophagic genes (atg12, becn1, sesn1, and dram1) with a reduced relapse free survival (RFS) and distant metastasis free survival (DMFS) of breast cancer patients carrying TP53 gene mutations conferring a prognostic value to this mutant p53-and autophagy-related signature. Interestingly, the mutant p53-driven mTOR stimulation sensitized cancer cells to the treatment with the mTOR inhibitor everolimus. All these results reveal a novel mechanism through which mutant p53 proteins promote cancer cell proliferation with the concomitant inhibition of autophagy. Copyright © 2016 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
KDM4B/JMJD2B is a p53 target gene that modulates the amplitude of p53 response after DNA damage

PubMed Central

Moon, Eui Jung; Razorenova, Olga V.; Krieg, Adam J.; von Eyben, Rie

2017-01-01

Abstract The p53 tumor suppressor protein plays a critical role in orchestrating the genomic response to various stress signals by acting as a master transcriptional regulator. Differential gene activity is controlled by transcription factors but also dependent on the underlying chromatin structure, especially on covalent histone modifications. After screening different histone lysine methyltransferases and demethylases, we identified JMJD2B/KDM4B as a p53-inducible gene in response to DNA damage. p53 directly regulates JMJD2B gene expression by binding to a canonical p53-consensus motif in the JMJD2B promoter. JMJD2B induction attenuates the transcription of key p53 transcriptional targets including p21, PIG3 and PUMA, and this modulation is dependent on the catalytic capacity of JMJD2B. Conversely, JMJD2B silencing led to an enhancement of the DNA-damage driven induction of p21 and PIG3. These findings indicate that JMJD2B acts in an auto-regulatory loop by which p53, through JMJD2B activation, is able to influence its own transcriptional program. Functionally, exogenous expression of JMJD2B enhanced subcutaneous tumor growth of colon cancer cells in a p53-dependent manner, and genetic inhibition of JMJD2B impaired tumor growth in vivo. These studies provide new insights into the regulatory effect exerted by JMJD2B on tumor growth through the modulation of p53 target genes. PMID:28073943
Modulation of p53β and p53γ expression by regulating the alternative splicing of TP53 gene modifies cellular response

PubMed Central

Marcel, V; Fernandes, K; Terrier, O; Lane, D P; Bourdon, J-C

2014-01-01

In addition to the tumor suppressor p53 protein, also termed p53α, the TP53 gene produces p53β and p53γ through alternative splicing of exons 9β and 9γ located within TP53 intron 9. Here we report that both TG003, a specific inhibitor of Cdc2-like kinases (Clk) that regulates the alternative splicing pre-mRNA pathway, and knockdown of SFRS1 increase expression of endogenous p53β and p53γ at mRNA and protein levels. Development of a TP53 intron 9 minigene shows that TG003 treatment and knockdown of SFRS1 promote inclusion of TP53 exons 9β/9γ. In a series of 85 primary breast tumors, a significant association was observed between expression of SFRS1 and α variant, supporting our experimental data. Using siRNA specifically targeting exons 9β/9γ, we demonstrate that cell growth can be driven by modulating p53β and p53γ expression in an opposite manner, depending on the cellular context. In MCF7 cells, p53β and p53γ promote apoptosis, thus inhibiting cell growth. By transient transfection, we show that p53β enhanced p53α transcriptional activity on the p21 and Bax promoters, while p53γ increased p53α transcriptional activity on the Bax promoter only. Moreover, p53β and p53γ co-immunoprecipitate with p53α only in the presence of p53-responsive promoter. Interestingly, although p53β and p53γ promote apoptosis in MCF7 cells, p53β and p53γ maintain cell growth in response to TG003 in a p53α-dependent manner. The dual activities of p53β and p53γ isoforms observed in non-treated and TG003-treated cells may result from the impact of TG003 on both expression and activities of p53 isoforms. Overall, our data suggest that p53β and p53γ regulate cellular response to modulation of alternative splicing pre-mRNA pathway by a small drug inhibitor. The development of novel drugs targeting alternative splicing process could be used as a novel therapeutic approach in human cancers. PMID:24926616
The Impact of a Common MDM2 SNP on the Sensitivity of Breast Cancer to Treatment

DTIC Science & Technology

2012-06-01

1993; Kussie, 1996 ; Lin, 1994; Freedman, 1999). Apart from its p53 ubiquitination function, MDM2 has other functions including nuclear- cytoplasmic...MDM2; however, it can be degraded by MDM2 (Shvarts, 1997; Shvarts, 1996 ; Okamoto, 2005). Appropriate expression of p53 propels cells down apoptotic...prognostic value for various endpoints in multiple tumor types (Bueso-Ramos, 1996 ; Khor, 2005; Kim, 2011; Marchetti, 1995;Marchetti, 1995; McCann, 1995
Epstein-Barr virus nuclear antigen 3C targets p53 and modulates its transcriptional and apoptotic activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yi Fuming; Saha, Abhik; Murakami, Masanao

The p53 tumor suppressor gene is one of the most commonly mutated genes in human cancers and the corresponding encoded protein induces apoptosis or cell-cycle arrest at the G1/S checkpoint in response to DNA damage. To date, previous studies have shown that antigens encoded by human tumor viruses such as SV40 large T antigen, adenovirus E1A and HPV E6 interact with p53 and disrupt its functional activity. In a similar fashion, we now show that EBNA3C, one of the EBV latent antigens essential for the B-cell immortalization in vitro, interacts directly with p53. Additionally, we mapped the interaction of EBNA3Cmore » with p53 to the C-terminal DNA-binding and the tetramerization domain of p53, and the region of EBNA3C responsible for binding to p53 was mapped to the N-terminal domain of EBNA3C (residues 130-190), previously shown to interact with a number of important cell-cycle components, specifically SCF{sup Skp2}, cyclin A, and cMyc. Furthermore, we demonstrate that EBNA3C substantially represses the transcriptional activity of p53 in luciferase based reporter assays, and rescues apoptosis induced by ectopic p53 expression in SAOS-2 (p53{sup -/-}) cells. Interestingly, we also show that the DNA-binding ability of p53 is diminished in the presence of EBNA3C. Thus, the interaction between the p53 and EBNA3C provides new insights into the mechanism(s) by which the EBNA3C oncoprotein can alter cellular gene expression in EBV associated human cancers.« less
Tumor Suppressor p53 Stimulates the Expression of Epstein-Barr Virus Latent Membrane Protein 1.

PubMed

Wang, Qianli; Lingel, Amy; Geiser, Vicki; Kwapnoski, Zachary; Zhang, Luwen

2017-10-15

Epstein-Barr virus (EBV) is associated with multiple human malignancies. EBV latent membrane protein 1 (LMP1) is required for the efficient transformation of primary B lymphocytes in vitro and possibly in vivo The tumor suppressor p53 plays a seminal role in cancer development. In some EBV-associated cancers, p53 tends to be wild type and overly expressed; however, the effects of p53 on LMP1 expression is not clear. We find LMP1 expression to be associated with p53 expression in EBV-transformed cells under physiological and DNA damaging conditions. DNA damage stimulates LMP1 expression, and p53 is required for the stimulation. Ectopic p53 stimulates endogenous LMP1 expression. Moreover, endogenous LMP1 blocks DNA damage-mediated apoptosis. Regarding the mechanism of p53-mediated LMP1 expression, we find that interferon regulatory factor 5 (IRF5), a direct target of p53, is associated with both p53 and LMP1. IRF5 binds to and activates a LMP1 promoter reporter construct. Ectopic IRF5 increases the expression of LMP1, while knockdown of IRF5 leads to reduction of LMP1. Furthermore, LMP1 blocks IRF5-mediated apoptosis in EBV-infected cells. All of the data suggest that cellular p53 stimulates viral LMP1 expression, and IRF5 may be one of the factors for p53-mediated LMP1 stimulation. LMP1 may subsequently block DNA damage- and IRF5-mediated apoptosis for the benefits of EBV. The mutual regulation between p53 and LMP1 may play an important role in EBV infection and latency and its related cancers. IMPORTANCE The tumor suppressor p53 is a critical cellular protein in response to various stresses and dictates cells for various responses, including apoptosis. This work suggests that an Epstein-Bar virus (EBV) principal viral oncogene is activated by cellular p53. The viral oncogene blocks p53-mediated adverse effects during viral infection and transformation. Therefore, the induction of the viral oncogene by p53 provides a means for the virus to cope with infection and DNA damage-mediated cellular stresses. This seems to be the first report that p53 activates a viral oncogene; therefore, the discovery would be interesting to a broad readership from the fields of oncology to virology. Copyright © 2017 American Society for Microbiology.
Growth factor independence-1 antagonizes a p53-induced DNA damage response pathway in lymphoblastic leukemia

PubMed Central

Khandanpour, Cyrus; Phelan, James D.; Vassen, Lothar; Schütte, Judith; Chen, Riyan; Horman, Shane R.; Gaudreau, Marie-Claude; Krongold, Joseph; Zhu, Jinfang; Paul, William E.; Dührsen, Ulrich; Göttgens, Bertie; Grimes, H. Leighton; Möröy, Tarik

2013-01-01

Summary Most patients with acute lymphoblastic leukemia (ALL) fail current treatments highlighting the need for better therapies. Since oncogenic signaling activates a p53-dependent DNA-damage response and apoptosis, leukemic cells must devise appropriate countermeasures. We show here that growth factor independence 1 (Gfi1) can serve such a function, since Gfi1 ablation exacerbates p53 responses, and lowers the threshold for p53-induced cell death. Specifically, Gfi1 restricts p53 activity and expression of pro-apoptotic p53 targets such as Bax, Noxa (Pmaip1) and Puma (Bbc3). Subsequently, Gfi1 ablation cures mice from leukemia and limits the expansion of primary human T-ALL xenografts in mice. This suggests that targeting Gfi1 could improve the prognosis of patients with T-ALL or other lymphoid leukemias. PMID:23410974
E3 ubiquitin ligase Pirh2 enhances tumorigenic properties of human non-small cell lung carcinoma cells

PubMed Central

Fedorova, Olga; Shuvalov, Oleg; Merkulov, Valeriy; Vasileva, Elena; Antonov, Alexey; Barlev, Nikolai A.

2016-01-01

The product of RCHY1 human gene, Pirh2, is a RING-finger containing E3 ligase that modifies p53 with ubiquitin residues resulting in its subsequent degradation in proteasomes. Transcription of RCHY1 is regulated by p53 itself thus forming a negative regulatory feedback loop. Functionally, by eliminating p53, Pirh2 facilitates tumorigenesis. However, the role of Pirh2 in cancer cells lacking p53 is yet not well understood. Therefore, we decided to elucidate the role of Pirh2 in p53-negative human non-small cell lung carcinoma cells, H1299. We found that ectopic expression of Pirh2 enhanced cell proliferation, resistance to doxorubicin, and increased migration potential. Ablation of Pirh2 by specific shRNA reversed these phenotypes. Mechanistically, Pirh2 increased mRNA and protein levels of the c-Myc oncogene. The bioinformatics data indicate that co-expression of both c-Myc and Pirh2 strongly correlated with poor survival of lung cancer patients. Collectively, our results suggest that Pirh2 can be considered as a potential pharmacological target for developing anticancer therapies to treat p53-negative cancers. PMID:28191284
Epigallocatechin-3-Gallate Prevents Autoimmune-Associated Down-Regulation of p21 in Salivary Gland Cells Through a p53-Independent Pathway

PubMed Central

Dickinson, Douglas; Yu, Hongfang; Ohno, Seiji; Thomas, Cristina; DeRossi, Scott; Ma, Yat-Ho; Yates, Nicole; Hahn, Emily; Bisch, Frederick; Yamamoto, Tetsuya; Hsu, Stephen

2015-01-01

The submandibular salivary glands of non-obese diabetic (NOD) mice, a model for Sjogren’s syndrome and type-1 diabetes, show an elevated level of proliferating cell nuclear antigen (PCNA), a protein involved in cell proliferation and repair of DNA damage. We reported previously that epigallocatechin-3-gallate (EGCG), the most abundant green tea catechin, normalizes the PCNA level. PCNA’s activity can be regulated by the cyclin-dependent kinase inhibitor p21, which is also important for epithelial cell differentiation. In turn, expression of p21 and PCNA are partially regulated by Rb phosphorylation levels. EGCG was found to modulate p21 expression in epithelial cells, suggesting that EGCG-induced p21 could be associated with down-regulation of PCNA in vivo. The current study examined the protein levels of p21 and p53 (which can up-regulate p21) in NOD mice fed with either water or EGCG, and the effect of EGCG on p21 and p53 in cell line models with either normal or defective Rb. In NOD mice, the p21 level was low, and EGCG normalized it. In contrast to HSG cells with functional Rb, negligible expression of p21 in NS-SV-AC cells that lack Rb was not altered by EGCG treatment. Inhibition of p53 by siRNA demonstrated that p21 and p53 were induced independently in HSG cells by a physiological concentration range of EGCG, suggesting p53 could be an important but not conditional factor associated with p21 expression. In conclusion, PCNA and p21 levels are altered inversely in the NOD model for SS and in HSG cells, and warrant further study as candidate new markers for salivary dysfunction associated with xerostomia. Induction of p21 by EGCG could provide clinically useful normalization of salivary glands by promoting differentiation and reducing PCNA levels. PMID:24329914
Low expression levels of ATM may substitute for CHEK2 /TP53 mutations predicting resistance towards anthracycline and mitomycin chemotherapy in breast cancer

PubMed Central

2012-01-01

Introduction Mutations affecting p53 or its upstream activator Chk2 are associated with resistance to DNA-damaging chemotherapy in breast cancer. ATM (Ataxia Telangiectasia Mutated protein) is the key activator of p53 and Chk2 in response to genotoxic stress. Here, we sought to evaluate ATM's potential role in resistance to chemotherapy. Methods We sequenced ATM and assessed gene expression levels in pre-treatment biopsies from 71 locally advanced breast cancers treated in the neoadjuvant setting with doxorubicin monotherapy or mitomycin combined with 5-fluorouracil. Findings were confirmed in a separate patient cohort treated with epirubicin monotherapy. Each tumor was previously analyzed for CHEK2 and TP53 mutation status. Results While ATM mutations were not associated with chemo-resistance, low ATM expression levels predicted chemo-resistance among patients with tumors wild-type for TP53 and CHEK2 (P = 0.028). Analyzing the ATM-chk2-p53 cascade, low ATM levels (defined as the lower 5 to 50% percentiles) or mutations inactivating TP53 or CHEK2 robustly predicted anthracycline resistance (P-values varying between 0.001 and 0.027 depending on the percentile used to define "low" ATM levels). These results were confirmed in an independent cohort of 109 patients treated with epirubicin monotherapy. In contrast, ATM-levels were not suppressed in resistant tumors harboring TP53 or CHEK2 mutations (P > 0.5). Conclusions Our data indicate loss of function of the ATM-Chk2-p53 cascade to be strongly associated with resistance to anthracycline/mitomycin-containing chemotherapy in breast cancer. PMID:22420423
Pifithrin-α provides neuroprotective effects at the level of mitochondria independently of p53 inhibition.

PubMed

Neitemeier, Sandra; Ganjam, Goutham K; Diemert, Sebastian; Culmsee, Carsten

2014-12-01

Impaired mitochondrial integrity and function are key features of intrinsic death pathways in neuronal cells. Therefore, key regulators of intrinsic death pathways acting upstream of mitochondria are potential targets for therapeutic approaches of neuroprotection. The tumor suppressor p53 is a well-established regulator of cellular responses towards different kinds of lethal stress, including oxidative stress. Recent reports suggested that p53 may affect mitochondrial integrity and function through both, transcriptional activation of mitochondria-targeted pro-death proteins and direct effects at the mitochondrial membrane. In the present study, we compared the effects of pharmacological inhibition of p53 by pifithrin-α with those of selective p53 gene silencing by RNA interference. Using MTT assay and real-time cell impedance measurements we confirmed the protective effect of both strategies against glutamate-induced oxidative stress in immortalized mouse hippocampal HT-22 neurons. Further, we observed full restoration of mitochondrial membrane potential and inhibition of glutamate-induced mitochondrial fragmentation by pifithrin-α which was, in contrast, not achieved by p53 gene silencing. Downregulation of p53 by siRNA decreased p53 transcriptional activity and reduced expression levels of p21 mRNA, while pifithrin-α did not affect these endpoints. These results suggest a neuroprotective effect of pifithrin-α which occurred at the level of mitochondria and independently of p53 inhibition.
p53 expression in patients with ulcerative colitis - associated with dysplasia and carcinoma: a systematic meta-analysis.

PubMed

Lu, Xiaohong; Yu, Yuanjie; Tan, Shiyun

2017-10-25

Tumor suppressor gene p53 expression has been reported in patients with ulcerative colitis (UC). However, the correlation between p53 expression and UC remains controversial. The aim of this meta-analysis was to investigate the association between p53 expression and different pathological types of UC. Publications were searched in the PubMed, Embase, EBSCO, Wangfang, and CNKI databases. The overall odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were summarized in this study. Final 19 papers were identified in this meta-analysis, including 1068 patients with UC and 130 normal tissue samples. Immunohistochemical p53 expression was significantly higher in UC without dysplasia and carcinoma (UC group) compared to normal tissue samples (OR = 3.14, P = 0.001), higher in UC with dysplasia than in UC group (OR = 10.76, P < 0.001), and higher in UC with colorectal cancer (CRC) than in UC with dysplasia (OR = 1.69, P = 0.035). Subgroup analysis of ethnicity (UC group vs. normal tissues) showed that p53 expression was correlated with UC in Asians, but not in Caucasians. When UC with dysplasia was compared to UC group, p53 expression was linked to UC with dysplasia among both Asians and Caucasians. When UC-CRC was compared to UC with dysplasia, p53 expression was not associated with UC-CRC in both Caucasians and Asians. p53 expression was closely associated with UC-CRC development. p53 expression showed different ethnic characteristics among different pathological types of UC.
Enhanced p53 gene transfer to human ovarian cancer cells using the cationic nonviral vector, DDC.

PubMed

Kim, Chong-Kook; Choi, Eun-Jeong; Choi, Sung-Hee; Park, Jeong-Sook; Haider, Khawaja Hasnain; Ahn, Woong Shick

2003-08-01

Previously we have formulated a new cationic liposome, DDC, composed of dioleoyltrimethylamino propane (DOTAP), 1,2-dioeoyl-3-phosphophatidylethanolamine (DOPE), and cholesterol (Chol), and it efficiently delivered plasmid DNA into ovarian cancer cells. Mutations in the p53 tumor suppressor gene are the most common molecular genetic abnormalities to be described in ovarian cancer. However, there has been so far no report of nonviral vector-mediated p53 gene deliveries in ovarian cancer. In this study, wild-type p53 DNA was transfected into the ovarian cancer cells, using the DDC as a nonviral vector and the expression and activity of p53 gene were evaluated both in vitro and in vivo. DDC liposomes were prepared by mixing DOTAP:DOPE:Chol in a 1:0.7:0.3 molar ratio using the extrusion method. Plasmid DNA (pp53-EGFP) and DDC complexes were transfected into ovarian carcinoma cells (OVCAR-3 cells) and gene expression was determined by reverse transcription-polymerase chain reaction and Western blot analysis. The cellular growth inhibition and apoptosis of DDC-mediated p53 transfection were assessed by trypan blue exclusion assay and annexin-V staining, respectively. The OVCAR-3 cells treated with DDC/pp53-EGFP complexes were inoculated into female balb/c nude mice and tumor growth was observed. The transfection of liposome-complexed p53 gene resulted in a high level of wild-type p53 mRNA and protein expressions in OVCAR-3 cells. In vitro cell growth assay showed growth inhibition of cancer cells transfected with DDC/pp53-EGFP complexes compared with the control cells. The reestablishment of wild-type p53 function in ovarian cancer cells restored the apoptotic pathway. Following the inoculation of DDC/pp53-EGFP complexes, the volumes of tumors in nude mice were significantly reduced more than 60% compared to the control group. The DDC-mediated p53 DNA delivery may have the potential for clinical application as nonviral vector-mediated ovarian cancer therapy due to its effective induction of apoptosis and tumor growth inhibition.
Analysis of TP53 gene expression and p53 level of human hypopharyngeal FaDu (HTB-43) head and neck cancer cell line after microRNA-181a inhibition.

PubMed

Cheah, Y K; Cheng, R W; Yeap, S K; Khoo, C H; See, H S

2014-03-17

The identification of new biomarkers for early detection of highly recurrent head and neck cancer is urgently needed. MicroRNAs (miRNAs) are small and non-coding RNAs that regulate cancer-related gene expression, such as tumor protein 53 (TP53) gene expression. This study was carried out to analyze TP53 gene expression using real-time PCR and to determine changes in intracellular p53 level by flow cytometry after downregulation of miRNA-181a miRNA inhibitor in the FaDu cell line. TP53 gene expression showed a 3-fold increment and the p53 protein level was also increased in the miRNA-181a-treated cells. In conclusion, miRNA-181a binds to the TP53 gene and inhibits its expression, decreasing the synthesis of p53.

A study on the effect of Helicobacter pylori infection on p53 expression in gastric cancer and gastritis tissues.

PubMed

Salih, Barik A; Gucin, Zuhal; Bayyurt, Nizamettin

2013-09-16

Helicobacter pylori cause damage to gastric epithelial cells and alterations in the p53 gene that lead to cancer development. This study aimed to determine the correlation of p53 expression with H. pylori using immunohistochemistry, RFLP-PCR, and histopathology. Gastric biopsy samples from gastric cancer (GC) (n = 54) and gastritis (n = 31) patients were examined for histopathological changes and expression of p53 protein by immunohistochemistry. Immunohistochemical analysis of p53 protein expression in H. pylori-positive GC sections showed an average of 44.3% positive cells in tumors and 6.9% in normal tissues, as compared to 16.4% and 4.4% in H. pylori-negative sections. P53 expression showed significant association with H. pylori (P = 0.005), invasion depth (P = 0.029) and inflammation reaction (P = 0.008). In gastritis sections, no difference in the average p53 staining in H. pylori-positive or -negative sections was seen. PCR-RFLP results also showed no difference in genotype frequencies of p53 in H. pylori-positive or -negative gastritis sections. Histopathology study of H. pylori-positive GC sections showed that 97.2% were the intestinal type and 2.8% the diffuse type, while in H. pylori-negative sections 35.2% were the intestinal type and 64.8% the diffuse type. Biopsy sections from H. pylori-positive gastritis patients revealed more severe inflammation than those of H. pylori-negative patients. Our results show that H. pylori infection affects p53 expression in GC. The average p53 expression was significantly higher in tumor than in normal tissues. In gastritis sections p53 expression was significantly associated with H. pylori.
Phytochemical regulation of the tumor suppressive microRNA, miR-34a, by p53-dependent and independent responses in human breast cancer cells

PubMed Central

Hargraves, Kris G.; He, Lin; Firestone, Gary L.

2016-01-01

The tumor suppressive microRNA miR-34a is transcriptionally regulated by p53 and shown to inhibit breast cancer cell proliferation as well as being a marker of increased disease free survival. Indole-3-carbinol (I3C) derived from cruciferous vegetables, artemisinin, extracted from the sweet wormwood plant, and artesunate, a semi-synthetic derivative of artemisinin, are phytochemicals with anti-tumorigenic properties however, little is known about the role of microRNAs in their mechanism of action. Human breast cancer cells expressing wild-type (MCF-7) or mutant p53 (T47D) were treated with a concentration range and time course of each phytochemical under conditions of cell cycle arrest as detected by flow cytometry to examine the potential connection between miR-34a expression and their anti-proliferative responses. Real-time PCR and western blot analysis of extracted RNA and total protein revealed artemsinin and artesunate increased miR-34a expression in a dose-dependent manner correlating with down-regulation of the miR-34a target gene, CDK4. I3C stimulation of miR-34a expression required functional p53, whereas, both artemisinin and artesunate up-regulated miR-34a expression regardless of p53 mutational status or in the presence of dominant negative p53. Phytochemical treatments inhibited the luciferase activity of a construct containing the wild-type 3′UTR of CDK4, but not those with a mutated miR-34a binding site, whereas, transfection of miR-34a inhibitors ablated the phytochemical mediated down-regulation of CDK4 and induction of cell cycle arrest. Our results suggest that miR-34a is an essential component of the anti-proliferative activities of I3C, artemisinin and artesunate and demonstrate that both wild-type p53 dependent and independent pathways are responsible for miR-34a induction. PMID:25789847
p53 is required for brain growth but is dispensable for resistance to nutrient restriction during Drosophila larval development

PubMed Central

Contreras, Esteban G.; Sierralta, Jimena

2018-01-01

Background Animal growth is influenced by the genetic background and the environmental circumstances. How genes promote growth and coordinate adaptation to nutrient availability is still an open question. p53 is a transcription factor that commands the cellular response to different types of stresses. In adult Drosophila melanogaster, p53 regulates the metabolic adaptation to nutrient restriction that supports fly viability. Furthermore, the larval brain is protected from nutrient restriction in a phenomenon called ‘brain sparing’. Therefore, we hypothesised that p53 may regulate brain growth and show a protective role over brain development under nutrient restriction. Results Here, we studied the function of p53 during brain growth in normal conditions and in animals subjected to developmental nutrient restriction. We showed that p53 loss of function reduced animal growth and larval brain size. Endogenous p53 was expressed in larval neural stem cells, but its levels and activity were not affected by nutritional stress. Interestingly, p53 knockdown only in neural stem cells was sufficient to decrease larval brain growth. Finally, we showed that in p53 mutant larvae under nutrient restriction, the energy storage levels were not altered, and these larvae generated adults with brains of similar size than wild-type animals. Conclusions Using genetic approaches, we demonstrate that p53 is required for proper growth of the larval brain. This developmental role of p53 does not have an impact on animal resistance to nutritional stress since brain growth in p53 mutants under nutrient restriction is similar to control animals. PMID:29621246
p53 is required for brain growth but is dispensable for resistance to nutrient restriction during Drosophila larval development.

PubMed

Contreras, Esteban G; Sierralta, Jimena; Glavic, Alvaro

2018-01-01

Animal growth is influenced by the genetic background and the environmental circumstances. How genes promote growth and coordinate adaptation to nutrient availability is still an open question. p53 is a transcription factor that commands the cellular response to different types of stresses. In adult Drosophila melanogaster, p53 regulates the metabolic adaptation to nutrient restriction that supports fly viability. Furthermore, the larval brain is protected from nutrient restriction in a phenomenon called 'brain sparing'. Therefore, we hypothesised that p53 may regulate brain growth and show a protective role over brain development under nutrient restriction. Here, we studied the function of p53 during brain growth in normal conditions and in animals subjected to developmental nutrient restriction. We showed that p53 loss of function reduced animal growth and larval brain size. Endogenous p53 was expressed in larval neural stem cells, but its levels and activity were not affected by nutritional stress. Interestingly, p53 knockdown only in neural stem cells was sufficient to decrease larval brain growth. Finally, we showed that in p53 mutant larvae under nutrient restriction, the energy storage levels were not altered, and these larvae generated adults with brains of similar size than wild-type animals. Using genetic approaches, we demonstrate that p53 is required for proper growth of the larval brain. This developmental role of p53 does not have an impact on animal resistance to nutritional stress since brain growth in p53 mutants under nutrient restriction is similar to control animals.
RITA can induce cell death in p53-defective cells independently of p53 function via activation of JNK/SAPK and p38

PubMed Central

Weilbacher, A; Gutekunst, M; Oren, M; Aulitzky, W E; van der Kuip, H

2014-01-01

Significant advances have been made in the development of small molecules blocking the p53/MDM2 interaction. The Mdm2 inhibitor Nutlin-3 is restricted to tumors carrying wtp53. In contrast, RITA, a compound that binds p53, has recently been shown also to restore transcriptional functions of mtp53. As more than 50% of solid tumors carry p53 mutations, RITA promises to be a more effective therapeutic strategy than Nutlin-3. We investigated effects of RITA on apoptosis, cell cycle and induction of 45 p53 target genes in a panel of 14 cell lines from different tumor entities with different p53 status as well as primary lymphocytes and fibroblasts. Nine cell strains expressed wtp53, four harbored mtp53, and three were characterized by the loss of p53 protein. A significant induction of cell death upon RITA was observed in 7 of 16 cell lines. The nonmalignant cells in our panel were substantially less sensitive. We found that in contrast to Nultin-3, RITA is capable to induce cell death not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells. Importantly, whereas p53 has a central role for RITA-mediated effects in wtp53 cells, neither p53 nor p63 or p73 were essential for the RITA response in mtp53 or p53-null cells in our panel demonstrating that besides the known p53-dependent action of RITA in wtp53 cells, RITA can induce cell death also independently of p53 in cells harboring defective p53. We identified an important role of both p38 and JNK/SAPK for sensitivity to RITA in these cells leading to a typical caspase- and BAX/BAK-dependent mitochondrial apoptosis. In conclusion, our data demonstrate that RITA can induce apoptosis through p38 and JNK/SAPK not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells, making RITA an interesting tumor-selective drug. PMID:25010984
RITA can induce cell death in p53-defective cells independently of p53 function via activation of JNK/SAPK and p38.

PubMed

Weilbacher, A; Gutekunst, M; Oren, M; Aulitzky, W E; van der Kuip, H

2014-07-10

Significant advances have been made in the development of small molecules blocking the p53/MDM2 interaction. The Mdm2 inhibitor Nutlin-3 is restricted to tumors carrying wtp53. In contrast, RITA, a compound that binds p53, has recently been shown also to restore transcriptional functions of mtp53. As more than 50% of solid tumors carry p53 mutations, RITA promises to be a more effective therapeutic strategy than Nutlin-3. We investigated effects of RITA on apoptosis, cell cycle and induction of 45 p53 target genes in a panel of 14 cell lines from different tumor entities with different p53 status as well as primary lymphocytes and fibroblasts. Nine cell strains expressed wtp53, four harbored mtp53, and three were characterized by the loss of p53 protein. A significant induction of cell death upon RITA was observed in 7 of 16 cell lines. The nonmalignant cells in our panel were substantially less sensitive. We found that in contrast to Nultin-3, RITA is capable to induce cell death not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells. Importantly, whereas p53 has a central role for RITA-mediated effects in wtp53 cells, neither p53 nor p63 or p73 were essential for the RITA response in mtp53 or p53-null cells in our panel demonstrating that besides the known p53-dependent action of RITA in wtp53 cells, RITA can induce cell death also independently of p53 in cells harboring defective p53. We identified an important role of both p38 and JNK/SAPK for sensitivity to RITA in these cells leading to a typical caspase- and BAX/BAK-dependent mitochondrial apoptosis. In conclusion, our data demonstrate that RITA can induce apoptosis through p38 and JNK/SAPK not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells, making RITA an interesting tumor-selective drug.
Transcriptional inhibition of p21{sup WAF1/CIP1} gene (CDKN1) expression by survivin is at least partially p53-dependent: Evidence for survivin acting as a transcription factor or co-factor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Lei; Pre-Doctoral Chinese Fellowship Student, Second West China Hospital, Sichuan University, Sichuan; Ling, Xiang

2012-05-04

Highlights: Black-Right-Pointing-Pointer Survivin inhibits the expression of p21 protein, mRNA and promoter activity. Black-Right-Pointing-Pointer Survivin neutralizes p53-induced p21 expression and promoter activity. Black-Right-Pointing-Pointer Survivin physically interacts with p53 in cancer cells. Black-Right-Pointing-Pointer Genetic silencing of endogenous survivin upregulates p21 in p53 wild type cancer cells. Black-Right-Pointing-Pointer Both p53 and survivin interacts on the two p53-binding sites in the p21 promoter. -- Abstract: Growing evidence suggests a role for the antiapoptotic protein survivin in promotion of cancer cell G1/S transition and proliferation. However, the underlying mechanism is unclear. Further, although upregulation of p21{sup WAF1/CIP1} by p53 plays an important role inmore » p53-mediated cell G1 arrests in response to various distresses, it is unknown whether survivin plays a role in the regulation of p21{sup WAF1/CIP1} expression. Here, we report that exogenous expression of survivin in p53-wild type MCF-7 breast cancer cells inhibits the expression of p21{sup WAF1/CIP1} protein, mRNA and promoter activity, while the survivin C84A mutant and antisense failed to do so. Cotransfection experiments in the p53 mutant H1650 lung cancer cell line showed that survivin neutralizes p53-induced p21{sup WAF1/CIP1} expression and promoter activity. Importantly, genetically silencing of endogenous survivin using lentiviral survivin shRNA also enhances endogenous p21 in p53 wild type cancer cells, suggesting the physiological relevance of the fining. We further demonstrated that both p53 and survivin interacts on the two p53-binding sites in the p21{sup WAF1/CIP1} promoter (-2313 to -2212; -1452 to -1310), and survivin physically interacts with p53 in cancer cells. Together, we propose that survivin may act as a transcription factor or cofactor to interact with p53 on the p21{sup WAF1/CIP1} promoter leading to the inhibition of p21{sup WAF1/CIP1} expression at least in part by neutralizing p53-mediated transcriptional activation of the p21 gene.« less
Accumulation of p53 in infectious mononucleosis tissues.

PubMed

Ehsan, A; Fan, H; Eagan, P A; Siddiqui, H A; Gulley, M L

2000-11-01

Epstein-Barr virus (EBV) infects lymphocytes, where it persists indefinitely for the life of the host; whether the virus interacts with p53 to maintain itself in these cells is unknown. Lymphoid biopsy samples from 10 patients with infectious mononucleosis (IM) were examined for expression of p53 by immunohistochemistry. Accumulation of p53 was detected in all 10 cases, primarily in large lymphocytes of the expanded paracortex. The presence of EBV was confirmed in all 10 cases by EBER1 (EBV-encoded RNA) in situ hybridization, whereas 11 non-IM control samples lacked significant EBER1 and did not express p53 in paracortical lymphocytes. Interestingly, EBV infection alone does not cause accumulation of intracellular p53, because many more cells expressed EBER1 than p53 in the IM tissues. To determine whether p53 was confined to the subset of infected cells in which viral replication was occurring, BZLF1 immunostains were performed. Viral BZLF1 was detected in 8 of 10 IM tissues; however, the paucity and small size of the BZLF1-expressing lymphocytes suggests that they are not the same cells overexpressing p53. To further examine the relationship between p53 and EBV gene expression, the tissues were studied for latent membrane protein 1 (LMP1) expression by immunohistochemistry. Viral LMP1 was observed in the large paracortical lymphocytes of all 10 cases of IM, indicating co-localization of p53 and LMP1 in these cells. Our findings confirm that p53 overexpression is not specific for nodal malignancy and that p53 accumulation is characteristic of IM. Because p53 was not coexpressed in the same cells as BZLF1, it appears that BZLF1 is not directly responsible for p53 accumulation. Nevertheless, co-localization of p53 and LMP1 in activated-appearing lymphocytes suggests that EBV infection is responsible for p53 accumulation. HUM PATHOL 31:1397-1403. Copyright 2000 by W.B. Saunders Company
Expression of p53 protein in advanced head and neck squamous cell carcinoma before and after chemotherapy.

PubMed

Dunphy, C H; Dunphy, F R; Boyd, J H; Varvares, M A; Kim, H J; Lowe, V; Dunleavy, T L; Rodriguez, J; McDonough, E M; Minster, J

1997-11-01

The expression of p53 protein has been reported to be in the range of 35% to 67% in head and neck squamous cell carcinoma (HNSCC). Mutations of the gene for p53 protein have been associated with rapidly proliferating tumors, and p53 protein expression has been shown to be a significant predictor of worse survival in surgically resected HNSCC. To determine whether p53 protein expression in advanced (stages III and IV) HNSCC has any impact on tumor response to 2 to 3 courses of paclitaxel (Taxol) and carboplatin, we prospectively studied prechemotherapy specimens from patients with previously untreated, advanced-stage HNSCC. We also attempted to study residual tumors after chemotherapy to determine if the p53 status of the tumor changed. The expression of p53 protein was evaluated by immunohistochemical analysis (clone BP53-12-1; Bio-Genex, San Ramon, Calif). Tertiary university medical center. Two to 3 courses of chemotherapy with paclitaxel and carboplatin. Pathologic complete remission or residual tumor. The results of p53 immunostaining were positive in 24 (67%) of 36 HNSCC specimens before chemotherapy. After chemotherapy, 8 patients achieved pathologic complete remission. Before chemotherapy, the tumor was p53 negative in 2 patients and positive in 6 patients. No correlation of p53 protein expression with response to chemotherapy was noted. The expression of p53 protein converted from positive to negative in 5 (42%) of 12 specimens from patients with residual tumor after chemotherapy, with no impact on clinical outcome.
Activation of Postnatal Neural Stem Cells Requires Nuclear Receptor TLX

PubMed Central

Niu, Wenze; Zou, Yuhua; Shen, ChengCheng; Zhang, Chun-Li

2011-01-01

Neural stem cells (NSCs) continually produce new neurons in postnatal brains. However, the majority of these cells stay in a non-dividing, inactive state. The molecular mechanism that is required for these cells to enter proliferation still remains largely unknown. Here, we show that nuclear receptor TLX (NR2E1) controls the activation status of postnatal NSCs in mice. Lineage tracing indicates that TLX-expressing cells give rise to both activated and inactive postnatal NSCs. Surprisingly, loss of TLX function does not result in spontaneous glial differentiation, but rather leads to a precipitous age-dependent increase of inactive cells with marker expression and radial morphology for NSCs. These inactive cells are mis-positioned throughout the granular cell layer of the dentate gyrus during development and can proliferate again after reintroducing ectopic TLX. RNA-seq analysis of sorted NSCs revealed a TLX-dependent global expression signature, which includes the p53 signaling pathway. TLX regulates p21 expression in a p53-dependent manner and acute removal of p53 can rescue the proliferation defect of TLX-null NSCs in culture. Together, these findings suggest that TLX acts as an essential regulator that ensures the proliferative ability of postnatal NSCs by controlling their activation through genetic interaction with p53 and other signaling pathways. PMID:21957244
Activation of postnatal neural stem cells requires nuclear receptor TLX.

PubMed

Niu, Wenze; Zou, Yuhua; Shen, Chengcheng; Zhang, Chun-Li

2011-09-28

Neural stem cells (NSCs) continually produce new neurons in postnatal brains. However, the majority of these cells stay in a nondividing, inactive state. The molecular mechanism that is required for these cells to enter proliferation still remains largely unknown. Here, we show that nuclear receptor TLX (NR2E1) controls the activation status of postnatal NSCs in mice. Lineage tracing indicates that TLX-expressing cells give rise to both activated and inactive postnatal NSCs. Surprisingly, loss of TLX function does not result in spontaneous glial differentiation, but rather leads to a precipitous age-dependent increase of inactive cells with marker expression and radial morphology for NSCs. These inactive cells are mispositioned throughout the granular cell layer of the dentate gyrus during development and can proliferate again after reintroduction of ectopic TLX. RNA-seq analysis of sorted NSCs revealed a TLX-dependent global expression signature, which includes the p53 signaling pathway. TLX regulates p21 expression in a p53-dependent manner, and acute removal of p53 can rescue the proliferation defect of TLX-null NSCs in culture. Together, these findings suggest that TLX acts as an essential regulator that ensures the proliferative ability of postnatal NSCs by controlling their activation through genetic interaction with p53 and other signaling pathways.
p53 and PCNA expression in advanced colorectal cancer: response to chemotherapy and long-term prognosis.

PubMed

Paradiso, A; Rabinovich, M; Vallejo, C; Machiavelli, M; Romero, A; Perez, J; Lacava, J; Cuevas, M A; Rodriquez, R; Leone, B; Sapia, M G; Simone, G; De Lena, M

1996-12-20

In a series of 71 patients with advanced colorectal cancer treated with biochemically modulated 5-fluorouracil (5-FU) and methotrexate (MTX), we investigated the relationship between the proliferating-cell nuclear antigen (PCNA) (PC10) and p53 (Pab1801) primary-tumor immunohistochemical expression with respect to clinical response and long-term prognosis. Nuclear p53 expression was demonstrated in 44% of samples (any number of positive tumor cells) while all tumors showed a certain degree of PCNA immunostaining. PCNA immunostaining was correlated with histopathologic grade and p53 expression, while p53 was not correlated with any of the parameters considered. The probability of clinical response to biochemically modulated 5-FU was independent of p53 and PCNA expression. p53 expression (all cut-off values) was not associated with short- or long-term clinical prognosis, whereas patients with higher PCNA primary-tumor expression showed longer survival from treatment and survival from diagnosis, according to univariate and multivariate analysis, particularly in the sub-set of colon-cancer patients. We conclude that the clinical response of advanced-colorectal-cancer patients to biochemically modulated 5-FU and MTX cannot be predicted by PCNA and p53 primary-tumor expression, but high PCNA expression appears to be independently related to long-term prognosis.
Stress Hormone Cortisol Enhances Bcl2 Like-12 Expression to Inhibit p53 in Hepatocellular Carcinoma Cells.

PubMed

Wu, Weizhong; Liu, Sanguang; Liang, Yunfei; Zhou, Zegao; Bian, Wei; Liu, Xueqing

2017-12-01

The pathogenesis of hepatocellular carcinoma (HC) is unclear. It is suggested that psychological stress associates with the pathogenesis of liver cancer. Bcl2-like protein 12 (Bcl2L12) suppresses p53 protein. This study tests a hypothesis that the major stress hormone, cortisol, inhibits the expression of p53 in HC cells (HCC) via up regulating the expression of Bcl2L12. Peripheral blood samples were collected from patients with HC to be analyzed for the levels of cortisol. HCC were cultured to assess the role of cortisol in the regulation of the expression of Bcl2L12 and p53 in HCC. We observed that the serum cortisol levels were higher in HC patients. Expression of Bcl2L12 in HCC was correlated with serum cortisol. Cortisol enhanced the Bcl2L12 expression in HCC. Bcl2L12 binding to the TP53 promoter was correlated with p53 expression in HCC. Cortisol increased the Bcl2L12 expression in HCC to inhibit p53 expression. Stress hormone cortisol suppresses p53 in HCC via enhancing Bcl2L12 expression in HCC. The results suggest that cortisol may be a therapeutic target for the treatment of HC.
The presence of p53 influences the expression of multiple human cytomegalovirus genes at early times postinfection.

PubMed

Hannemann, Holger; Rosenke, Kyle; O'Dowd, John M; Fortunato, Elizabeth A

2009-05-01

Human cytomegalovirus (HCMV) is a common cause of morbidity and mortality in immunocompromised and immunosuppressed individuals. During infection, HCMV is known to employ host transcription factors to facilitate viral gene expression. To further understand the previously observed delay in viral replication and protein expression in p53 knockout cells, we conducted microarray analyses of p53(+/+) and p53(-/-) immortalized fibroblast cell lines. At a multiplicity of infection (MOI) of 1 at 24 h postinfection (p.i.), the expression of 22 viral genes was affected by the absence of p53. Eleven of these 22 genes (group 1) were examined by real-time reverse transcriptase, or quantitative, PCR (q-PCR). Additionally, five genes previously determined to have p53 bound to their nearest p53-responsive elements (group 2) and three control genes without p53 binding sites in their upstream sequences (group 3) were also examined. At an MOI of 1, >3-fold regulation was found for five group 1 genes. The expression of group 2 and 3 genes was not changed. At an MOI of 5, all genes from group 1 and four of five genes from group 2 were found to be regulated. The expression of control genes from group 3 remained unchanged. A q-PCR time course of four genes revealed that p53 influences viral gene expression most at immediate-early and early times p.i., suggesting a mechanism for the reduced and delayed production of virions in p53(-/-) cells.
Frequent downregulation of miR-34 family in human ovarian cancers.

PubMed

Corney, David C; Hwang, Chang-Il; Matoso, Andres; Vogt, Markus; Flesken-Nikitin, Andrea; Godwin, Andrew K; Kamat, Aparna A; Sood, Anil K; Ellenson, Lora H; Hermeking, Heiko; Nikitin, Alexander Yu

2010-02-15

The miR-34 family is directly transactivated by tumor suppressor p53, which is frequently mutated in human epithelial ovarian cancer (EOC). We hypothesized that miR-34 expression would be decreased in EOC and that reconstituted miR-34 expression might reduce cell proliferation and invasion of EOC cells. miR-34 expression was determined by quantitative reverse transcription-PCR and in situ hybridization in a panel of 83 human EOC samples. Functional characterization of miR-34 was accomplished by reconstitution of miR-34 expression in EOC cells with synthetic pre-miR molecules followed by determining changes in proliferation, apoptosis, and invasion. miR-34a expression is decreased in 100%, and miR-34b*/c in 72%, of EOC with p53 mutation, whereas miR-34a is also downregulated in 93% of tumors with wild-type p53. Furthermore, expression of miR-34b*/c is significantly reduced in stage IV tumors compared with stage III (P = 0.0171 and P = 0.0029, respectively). Additionally, we observed promoter methylation and copy number variations at mir-34. In situ hybridization showed that miR-34a expression is inversely correlated with MET immunohistochemical staining, consistent with translational inhibition by miR-34a. Finally, miR-34 reconstitution experiments in p53 mutant EOC cells resulted in reduced proliferation, motility, and invasion, the latter of which was dependent on MET expression. Our work suggests that miR-34 family plays an important role in EOC pathogenesis and reduced expression of miR-34b*/c may be particularly important for progression to the most advanced stages. Part of miR-34 effects on motility and invasion may be explained by regulation of MET, which is frequently overexpressed in EOC.
Bcl-2 protein expression associated with resistance to apoptosis in clear cell adenocarcinomas of the vagina and cervix expressing wild-type p53.

PubMed

Waggoner, S E; Baunoch, D A; Anderson, S A; Leigh, F; Zagaja, V G

1998-09-01

Clear cell adenocarcinomas (CCAs) of the vagina and cervix are rare tumors that often overexpress wild-type p53. In vitro, expression of protooncogene bcl-2 can block p53-mediated apoptosis. The objective of this study was to determine if bcl-2 is expressed in CCAs and whether this expression is associated with inhibition of apoptosis. Twenty-one paraffin-embedded clear cell adenocarcinomas were immunohistochemically stained for bcl-2 (antibody M 887, Dako, Carpinteria, CA) and DNA fragmentation (ApopTag, Oncor, Gaithersburg, MD), a marker for apoptosis. Fifteen tumors were associated with in utero exposure to diethylstilbestrol (DES). Prior p53 gene analysis had indicated the presence of wild-type p53 in each tumor. Human lymphoid tissue containing bcl-2-expressing lymphocytes and DNase I-exposed CCA tissue sections were used as positive controls for the bcl-2 and apoptosis assays, respectively. Expression of bcl-2 and DNA fragmentation was classified (0 to 3+) according to percentage of positive cells and intensity of staining. Expression of bcl-2 was identified in each CCA examined, and was strongly positive (2+ to 3+) in 18 of 21 samples. Despite the presence of wild-type p53, only 4 of 21 tumors showed evidence of apoptosis as assessed through DNA fragmentation. DNA damage leads to increased intracellular p53 levels. Overexpression of p53 induces apoptosis as a means of protecting organisms from the development of malignancy. CCAs of the vagina and cervix, which contain wild-type p53 genes and often overexpress p53 protein, presumably have evolved mechanisms to avoid p53-induced apoptosis. Our observations are consistent with the hypothesis that overexpression of bcl-2 can inhibit p53-mediated apoptosis and suggest a mechanism by which these rare tumors can arise without mutation of the p53 gene.
Cisplatin fails to induce puma mediated apoptosis in mucosal melanomas

PubMed Central

Fritsche, Marie Kristin; Metzler, Veronika; Becker, Karen; Plettenberg, Christian; Heiser, Clemens; Hofauer, Benedikt; Knopf, Andreas

2015-01-01

Objectives Mucosal melanomas (MM) are aggressive subtypes of common melanomas. It remains unclear whether limitations in their resectability or their distinctive molecular mechanisms are responsible for the aggressive phenotype. Methods In total, 112 patients with cutaneous melanomas (CM) and 27 patients with MM were included. Clinical parameters were analysed using Chi square, Fisher exact and student's t-test. Survival rates were calculated by Kaplan–Meier. Analysis of p53, p21, Mdm2, Hipk2, Gadd45, Puma, Bax, Casp9 and Cdk1 via quantitative PCR and immunohistochemistry (IHC) was performed. TP53 induction after cisplatin treatment was analysed in 10 cell lines (melanocytes, four MM and five CM) using western blot (WB) and qPCR. Results The overall/recurrence-free survival differed significantly between MM (40 months and 30 months) and CM (90 months and 107 months; p < 0.001). IHC and WB confirmed high p53 expression in all melanomas. Hipk2 and Gadd45 showed significantly higher expressions in CM (p < 0.005; p = 0.004). QPCR and WB of wild-type cell lines demonstrated no differences for p53, p21, Mdm2, Bax and Casp9. WB failed to detect Puma in MM, while Cdk1 regulation occurred exclusively in MM. Conclusions The aggressive phenotype of MM did not appear to be due to differential expressions of p53, p21, Mdm2, Bax or Casp9. A non-functional apoptosis in MM may have further clinical implications. PMID:25831048
p53 and PCNA Expression in Keratocystic Odontogenic Tumors Compared with Selected Odontogenic Cysts

PubMed Central

Seyedmajidi, Maryam; Nafarzadeh, Shima; Siadati, Sepideh; Shafaee, Shahryar; Bijani, Ali; Keshmiri, Nazanin

2013-01-01

p53 and PCNA expression in keratocystic odontogenic tumors compared with selected odontogenic cysts Summary: The aim of this study was to evaluate p53 and PCNA expression in different odontogenic lesions regarding their different clinical behaviors. Slices prepared from 94 paraffin-embedded tissue blocks (25 radicular cysts (RC), 23 dentigerous cysts (DC), 23 keratocystic odontogenic tumors (KCOT) and 23 calcifying cystic odontogenic tumors (CCOT)) were stained with p53 and PCNA antibodies using immunohistochemistry procedure. The highest level of p53 expression was in the basal layer of RC, and the highest level of PCNA expression was in the suprabasal layer of KCOT. The differences of p53 expression in basal and suprabasal layers as well as PCNA expression in the suprabasal layer were significant but there was no significant difference in PCNA expression in the basal layer of these lesions. The expression of p53 in the basal layer of RC was higher than in other cysts. This may be due to intensive inflammatory infiltration. Also, the high level of PCNA expression in the suprabasal layer of KCOT may justify its neoplastic nature and tendency to recurrence. KCOT and calcifying cystic odontogenic tumors did not show similar expression of studied biomarkers. PMID:24551811
A new invertebrate member of the p53 gene family is developmentally expressed and responds to polychlorinated biphenyls.

PubMed Central

Jessen-Eller, Kathryn; Kreiling, Jill A; Begley, Gail S; Steele, Marjorie E; Walker, Charles W; Stephens, Raymond E; Reinisch, Carol L

2002-01-01

The cell-cycle checkpoint protein p53 both directs terminal differentiation and protects embryos from DNA damage. To study invertebrate p53 during early development, we identified three differentially expressed p53 family members (p53, p97, p120) in the surf clam, Spisula solidissima. In these mollusks, p53 and p97 occur in both embryonic and adult tissue, whereas p120 is exclusively embryonic. We sequenced, cloned, and characterized p120 cDNA. The predicted protein, p120, resembles p53 across all evolutionarily conserved regions and contains a C-terminal extension with a sterile alpha motif (SAM) as in p63 and p73. These vertebrate forms of p53 are required for normal inflammatory, epithelial, and neuronal development. Unlike clam p53 and p97, p120 mRNA and protein levels are temporally expressed in embryos, with mRNA levels decreasing with increasing p120 protein (R(2) = 0.97). Highest surf clam p120 mRNA levels coincide with the onset of neuronal growth. In earlier work we have shown that neuronal development is altered by exposure to polychlorinated biphenyls (PCBs), a neurotoxic environmental contaminant. In this study we show that PCBs differentially affect expression of the three surf clam p53 family members. p120 mRNA and protein are reduced the most and earliest in development, p97 protein shows a smaller and later reduction, and p53 protein levels do not change. For the first time we report that unlike p53 and p97, p120 is specifically embryonic and expressed in a time-dependent manner. Furthermore, p120 responds to PCBs by 48 hr when PCB-induced suppression of the serotonergic nervous system occurs. PMID:11940455
Poly(beta-amino ester) nanoparticle-delivery of p53 has activity against small cell lung cancer in vitro and in vivo

PubMed Central

Kamat, Chandrashekhar D.; Shmueli, Ron B.; Connis, Nick; Rudin, Charles M.; Green, Jordan J.; Hann, Christine L.

2013-01-01

Small cell lung cancer (SCLC) is an aggressive disease with one of the highest case-fatality rates among cancer. The recommended therapy for SCLC has not changed significantly over the past 30 years; new therapeutic approaches are a critical need. TP53 is mutated in the majority of SCLC cases and its loss is required in transgenic mouse models of the disease. We synthesized an array of biodegradable poly(beta-amino ester) (PBAE) polymers which self-assemble with DNA and assayed for transfection efficiency in the p53-mutant H446 SCLC cell line using high-throughput methodologies. Two of the top candidates were selected for further characterization and TP53 delivery in vitro and in vivo. Nanoparticle delivery of TP53 resulted in expression of exogenous p53, induction of p21, induction of apoptosis and accumulation of cells in sub-G1 consistent with functional p53 activity. Intratumoral injection of subcutaneous H446 xenografts with polymers carrying TP53 caused marked tumor growth inhibition. This is the first demonstration of TP53 gene therapy in SCLC using non-viral polymeric nanoparticles. This technology may have general applicability as a novel anti-cancer strategy based on restoration of tumor suppressor gene function. PMID:23364678

In vitro cytotoxic potential of friedelin in human MCF-7 breast cancer cell: Regulate early expression of Cdkn2a and pRb1, neutralize mdm2-p53 amalgamation and functional stabilization of p53.

PubMed

Subash-Babu, Pandurangan; Li, David K; Alshatwi, Ali A

2017-10-02

We aimed to explore the cytotoxic and apoptotic effect of friedelin on breast cancer MCF-7 cells. Cytotoxic effect of friedelin on MCF-7 cells was analyzed using MTT, cell and nuclear morphology. The apoptosis mechanism of friedelin on MCF-7 cells was analyzed using real-time PCR. Friedelin potentially inhibit 78% of MCF-7 cell's growth, the IC 50 value was 1.8μM in 24h and 1.2μM in 48h. Friedelin increased ROS significantly and DNA damage was confirmed by tunel assay. We found characteristically 52% apoptotic cells and 6% necrotic cells in PI, AO/ErBr staining after 48h treatment with 1.2μM of friedelin. Apoptosis was confirmed by significantly (p≤0.001) increased tumor suppressor gene Cdkn1a, pRb2, p53, Nrf2, caspase-3 and decreased Bcl-2, mdm2 & PCNA expression after 48h. In conclusion, friedelin effectively inhibit breast cancer MCF-7 cell growth, it was associated with early expression of Cdkn1a, pRb2 and activation of p53 and caspases. Copyright © 2017. Published by Elsevier GmbH.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Shi-Wei; Wu, Chun-Ying; Wang, Yen-Ting

Compound C, a well-known inhibitor of the intracellular energy sensor AMP-activated protein kinase (AMPK), has been reported to cause apoptotic cell death in myeloma, breast cancer cells and glioma cells. In this study, we have demonstrated that compound C not only induced autophagy in all tested skin cancer cell lines but also caused more apoptosis in p53 wildtype skin cancer cells than in p53-mutant skin cancer cells. Compound C can induce upregulation, phosphorylation and nuclear translocalization of the p53 protein and upregulate expression of p53 target genes in wildtype p53-expressing skin basal cell carcinoma (BCC) cells. The changes of p53more » status were dependent on DNA damage which was caused by compound C induced reactive oxygen species (ROS) generation and associated with activated ataxia-telangiectasia mutated (ATM) protein. Using the wildtype p53-expressing BCC cells versus stable p53-knockdown BCC sublines, we present evidence that p53-knockdown cancer cells were much less sensitive to compound C treatment with significant G2/M cell cycle arrest and attenuated the compound C-induced apoptosis but not autophagy. The compound C induced G2/M arrest in p53-knockdown BCC cells was associated with the sustained inactive Tyr15 phosphor-Cdc2 expression. Overall, our results established that compound C-induced apoptosis in skin cancer cells was dependent on the cell's p53 status. - Highlights: ► Compound C caused more apoptosis in p53 wildtype than p53-mutant skin cancer cells. ► Compound C can upregulate p53 expression and induce p53 activation. ► Compound C induced p53 effects were dependent on ROS induced DNA damage pathway. ► p53-knockdown attenuated compound C-induced apoptosis but not autophagy. ► Compound C-induced apoptosis in skin cancer cells was dependent on p53 status.« less
[6]-Gingerol Induces Cell Cycle Arrest and Cell Death of Mutant p53-expressing Pancreatic Cancer Cells

PubMed Central

Park, Yon Jung; Wen, Jing; Bang, Seungmin; Park, Seung Woo

2006-01-01

[6]-Gingerol, a major phenolic compound derived from ginger, has anti-bacterial, anti-inflammatory and anti-tumor activities. While several molecular mechanisms have been described to underlie its effects on cells in vitro and in vivo, the underlying mechanisms by which [6]-gingerol exerts anti-tumorigenic effects are largely unknown. The purpose of this study was to investigate the action of [6]-gingerol on two human pancreatic cancer cell lines, HPAC expressing wild-type (wt) p53 and BxPC-3 expressing mutated p53. We found that [6]-gingerol inhibited the cell growth through cell cycle arrest at G1 phase in both cell lines. Western blot analyses indicated that [6]-gingerol decreased both Cyclin A and Cyclin-dependent kinase (Cdk) expression. These events led to reduction in Rb phosphorylation followed by blocking of S phase entry. p53 expression was decreased by [6]-gingerol treatment in both cell lines suggesting that the induction of Cyclin-dependent kinase inhibitor, p21cip1, was p53-independent. [6]-Gingerol induced mostly apoptotic death in the mutant p53-expressing cells, while no signs of early apoptosis were detected in wild type p53-expressing cells and this was related to the increased phosphorylation of AKT. These results suggest that [6]-gingerol can circumvent the resistance of mutant p53-expressing cells towards chemotherapy by inducing apoptotic cell death while it exerts cytostatic effect on wild type p53-expressing cells by inducing temporal growth arrest. PMID:17066513
Targeting MDM2 for Treatment of Adenoid Cystic Carcinoma

PubMed Central

Warner, Kristy A.; Nör, Felipe; Acasigua, Gerson A.; Martins, Manoela D.; Zhang, Zhaocheng; McLean, Scott A.; Spector, Matthew E.; Chepeha, Douglas B.; Helman, Joseph; Wick, Michael J.; Moskaluk, Christopher A.; Castilho, Rogerio M.; Pearson, Alexander T.; Wang, Shaomeng; Nör, Jacques E.

2016-01-01

Purpose There are no effective treatment options for patients with advanced adenoid cystic carcinoma (ACC). Here, we evaluated the effect of a new small molecule inhibitor of the MDM2-p53 interaction (MI-773) in preclinical models of ACC. Experimental Design To evaluate the anti-tumor effect of MI-773, we administered it to mice harboring 3 different patient-derived xenograft (PDX) models of ACC expressing functional p53. The effect of MI-773 on MDM2, p53, phospho-p53 and p21 was examined by Western blots in 5 low passage primary human ACC cell lines and in MI-773-treated PDX tumors. Results Single agent MI-773 caused tumor regression in the 3 PDX models of ACC studied here. For example, we observed a tumor growth inhibition (TGI) index of 127% in UM-PDX-HACC-5 tumors that was associated with an increase in the fraction of apoptotic cells (p=0.015). The number of p53-positive cells was increased in MI-773-treated PDX tumors (p<0.001), with a correspondent shift in p53 localization from the nucleus to the cytoplasm. Western blots demonstrated that MI-773 potently induced expression of p53 and its downstream targets p21, MDM2 and induced phosphorylation of p53 (serine 392) in low passage primary human ACC cells. Notably, MI-773 induced a dose-dependent increase in the fraction of apoptotic ACC cells and in the fraction of cells in the G1 phase of cell cycle (p<0.05). Conclusions Collectively, these data demonstrate that therapeutic inhibition of the MDM2-p53 interaction with MI-773 activates downstream effectors of apoptosis and causes robust tumor regression in preclinical models of adenoid cystic carcinoma. PMID:26936915
E2 Ubiquitin-conjugating Enzyme, UBE2C Gene, Is Reciprocally Regulated by Wild-type and Gain-of-Function Mutant p53.

PubMed

Bajaj, Swati; Alam, Sk Kayum; Roy, Kumar Singha; Datta, Arindam; Nath, Somsubhra; Roychoudhury, Susanta

2016-07-01

Spindle assembly checkpoint governs proper chromosomal segregation during mitosis to ensure genomic stability. At the cellular level, this event is tightly regulated by UBE2C, an E2 ubiquitin-conjugating enzyme that donates ubiquitin to the anaphase-promoting complex/cyclosome. This, in turn, facilitates anaphase-onset by ubiquitin-mediated degradation of mitotic substrates. UBE2C is an important marker of chromosomal instability and has been associated with malignant growth. However, the mechanism of its regulation is largely unexplored. In this study, we report that UBE2C is transcriptionally activated by the gain-of-function (GOF) mutant p53, although it is transcriptionally repressed by wild-type p53. We showed that wild-type p53-mediated inhibition of UBE2C is p21-E2F4-dependent and GOF mutant p53-mediated transactivation of UBE2C is NF-Y-dependent. We further explored that DNA damage-induced wild-type p53 leads to spindle assembly checkpoint arrest by repressing UBE2C, whereas mutant p53 causes premature anaphase exit by increasing UBE2C expression in the presence of 5-fluorouracil. Identification of UBE2C as a target of wild-type and GOF mutant p53 further highlights the contribution of p53 in regulation of spindle assembly checkpoint. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.
Malat1 as an evolutionarily conserved lncRNA, plays a positive role in regulating proliferation and maintaining undifferentiated status of early-stage hematopoietic cells.

PubMed

Ma, Xian-Yong; Wang, Jian-Hui; Wang, Jing-Lan; Ma, Charles X; Wang, Xiao-Chun; Liu, Feng-Song

2015-09-03

The metastasis-associated lung adenocarcinoma transcription 1 (Malat1) is a highly conserved long non-coding RNA (lncRNA) gene. Previous studies showed that Malat1 is abundantly expressed in many tissues and involves in promoting tumor growth and metastasis by modulating gene expression and target protein activities. However, little is known about the biological function and regulation mechanism of Malat1 in normal cell proliferation. In this study we conformed that Malat1 is highly conserved across vast evolutionary distances amongst 20 species of mammals in terms of sequence, and found that mouse Malat1 expresses in tissues of liver, kidney, lung, heart, testis, spleen and brain, but not in skeletal muscle. After treating erythroid myeloid lymphoid (EML) cells with All-trans Retinoic Acid (ATRA), we investigated the expression and regulation of Malat1 during hematopoietic differentiation, the results showed that ATRA significantly down regulates Malat1 expression during the differentiation of EML cells. Mouse LRH (Lin-Rhodamine(low) Hoechst(low)) cells that represent the early-stage progenitor cells show a high level of Malat1 expression, while LRB (Lin - Hoechst(Low) Rhodamine(Bright)) cells that represent the late-stage progenitor cells had no detectable expression of Malat1. Knockdown experiment showed that depletion of Malat1 inhibits the EML cell proliferation. Along with the down regulation of Malat1, the tumor suppressor gene p53 was up regulated during the differentiation. Interestingly, we found two p53 binding motifs with help of bioinformatic tools, and the following chromatin immunoprecipitation (ChIP) test conformed that p53 acts as a transcription repressor that binds to Malat1's promoter. Furthermore, we testified that p53 over expression in EML cells causes down regulation of Malat1. In summary, this study indicates Malat1 plays a critical role in maintaining the proliferation potential of early-stage hematopoietic cells. In addition to its biological function, the study also uncovers the regulation pattern of Malat1 expression mediated by p53 in hematopoietic differentiation. Our research shed a light on exploring the Malat1 biological role including therapeutic significance to inhibit the proliferation potential of malignant cells.
Loss of DLK expression in WI-38 human diploid fibroblasts induces a senescent-like proliferation arrest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daviau, Alex; Couture, Jean-Philippe; Blouin, Richard, E-mail: Richard.Blouin@USherbrooke.ca

Highlights: {yields} Role of DLK in cell proliferation. {yields} Modulation of DLK expression during cell cycle progression. {yields} DLK knockdown induces proliferation arrest and senescence. {yields} DLK-depleted cells display loss of cyclin D1 and up-regulation of p21. {yields} DLK participates in cell proliferation by modulating cell cycle regulator expression. -- Abstract: DLK, a serine/threonine kinase that functions as an upstream activator of the mitogen-activated protein kinase (MAPK) pathways, has been shown to play a role in development, cell differentiation, apoptosis and neuronal response to injury. Interestingly, recent studies have shown that DLK may also be required for cell proliferation, althoughmore » little is known about its specific functions. To start addressing this issue, we studied how DLK expression is modulated during cell cycle progression and what effect DLK depletion has on cell proliferation in WI-38 fibroblasts. Our results indicate that DLK protein levels are low in serum-starved cells, but that serum addition markedly stimulated it. Moreover, RNA interference experiments demonstrate that DLK is required for ERK activity, expression of the cell cycle regulator cyclin D1 and proliferation of WI-38 cells. DLK-depleted cells also show a senescent phenotype as revealed by senescence-associated galactosidase activity and up-regulation of the senescence pathway proteins p53 and p21. Consistent with a role for p53 in this response, inhibition of p53 expression by RNA interference significantly alleviated senescence induced by DLK knockdown. Together, these findings indicate that DLK participates in cell proliferation and/or survival, at least in part, by modulating the expression of cell cycle regulatory proteins.« less
Crocin improves renal function by declining Nox-4, IL-18, and p53 expression levels in an experimental model of diabetic nephropathy.

PubMed

Yaribeygi, Habib; Mohammadi, Mohammad T; Rezaee, Ramin; Sahebkar, Amirhossein

2018-03-25

Oxidative damage, inflammation and apoptosis play significant roles in diabetic nephropathy. Previous studies demonstrated anti-inflammatory and anti-oxidative effects of crocin, but there is no evidence about its effects on IL-18, NOX-4, and p53 expression in diabetic kidneys. The aim of this study was to evaluate possible effects of crocin on improving main mechanisms underlying diabetic nephropathy. Male Wistar rats were randomly divided into four separate groups as normal (C), normal treated (CC), diabetic (D), and diabetic treated (DC) (n = 6). Diabetes was induced by a single dose of streptozotocin (40 mg/kg/intravenous). Treated groups received crocin (40 mg/kg, intraperitoneal) for 8 weeks. At the end of the 8th week of the study, all rats were sacrificed and urine, blood and tissue were collected. Levels of urea, uric acid, creatinine and glucose were determined collected sera, and proteinuria was measured in urine samples. Moreover, the contents of malondialdehyde (MDA), nitrate, and glutathione (GLT) as well as catalase (CAT) and superoxide dismutase (SOD) enzymes activities were measured. The expression of NOX-4, IL-18, and p53 at both mRNA and protein levels were also assessed. Hyperglycemia significantly increased proteinuria in diabetic rats (D). Also, depressed antioxidant defense system potency, but increased NOX-4 expression and free radicals production resulting in oxidative stress, were observed. Moreover, expressions of IL-18 (as a marker of inflammation) and p53 (as a marker of apoptosis) were increased. These outcomes were accompanied by enhanced histological damages and renal failure but, treatment with crocin improved these deteriorations, and ameliorated renal function. It potentiated renal cells antioxidant defense system and declined inflammation. Also, crocin lowered apoptosis and improved histological damages in renal cells. Oxidative stress, inflammation and apoptosis are considered three main mechanisms underlying diabetic nephropathy. Treatment with crocin prevented these deleterious effects and improved renal function under diabetic conditions. © 2018 Wiley Periodicals, Inc.
The Isoforms of the p53 Protein

PubMed Central

Khoury, Marie P.; Bourdon, Jean-Christophe

2010-01-01

p53 is a transcription factor with a key role in the maintenance of genetic stability and therefore preventing cancer formation. It belongs to a family of genes composed of p53, p63, and p73. The p63 and p73 genes have a dual gene structure with an internal promoter in intron-3 and together with alternative splicing, can express 6 and 29 mRNA variants, respectively. Such a complex expression pattern had not been previously described for the p53 gene, which was not consistent with our understanding of the evolution of the p53 gene family. Consequently, we revisited the human p53 gene structure and established that it encodes nine different p53 protein isoforms because of alternative splicing, alternative promoter usage, and alternative initiation sites of translation. Therefore, the human p53 gene family (p53, p63, and p73) has a dual gene structure. We determined that the dual gene structure is conserved in Drosophila and in zebrafish p53 genes. The conservation through evolution of the dual gene structure suggests that the p53 isoforms play an important role in p53 tumor-suppressor activity. We and others have established that the p53 isoforms can regulate cell-fate outcome in response to stress, by modulating p53 transcriptional activity in a promoter and stress-dependent manner. We have also shown that the p53 isoforms are abnormally expressed in several types of human cancers, suggesting that they play an important role in cancer formation. The determination of p53 isoforms' expression may help to link clinical outcome to p53 status and to improve cancer patient treatment. PMID:20300206
Changes in O-Linked N-Acetylglucosamine (O-GlcNAc) Homeostasis Activate the p53 Pathway in Ovarian Cancer Cells*

PubMed Central

de Queiroz, Rafaela Muniz; Madan, Rashna; Chien, Jeremy; Dias, Wagner Barbosa; Slawson, Chad

2016-01-01

O-GlcNAcylation is a dynamic post-translational modification consisting of the addition of a single N-acetylglucosamine sugar to serine and threonine residues in proteins by the enzyme O-linked β-N-acetylglucosamine transferase (OGT), whereas the enzyme O-GlcNAcase (OGA) removes the modification. In cancer, tumor samples present with altered O-GlcNAcylation; however, changes in O-GlcNAcylation are not consistent between tumor types. Interestingly, the tumor suppressor p53 is modified by O-GlcNAc, and most solid tumors contain mutations in p53 leading to the loss of p53 function. Because ovarian cancer has a high frequency of p53 mutation rates, we decided to investigate the relationship between O-GlcNAcylation and p53 function in ovarian cancer. We measured a significant decrease in O-GlcNAcylation of tumor tissue in an ovarian tumor microarray. Furthermore, O-GlcNAcylation was increased, and OGA protein and mRNA levels were decreased in ovarian tumor cell lines not expressing the protein p53. Treatment with the OGA inhibitor Thiamet-G (TMG), silencing of OGA, or overexpression of OGA and OGT led to p53 stabilization, increased nuclear localization, and increased protein and mRNA levels of p53 target genes. These data suggest that changes in O-GlcNAc homeostasis activate the p53 pathway. Combination treatment of the chemotherapeutic cisplatin with TMG decreased tumor cell growth and enhanced cell cycle arrest without impairing cytotoxicity. The effects of TMG on tumor cell growth were partially dependent on wild type p53 activation. In conclusion, changes in O-GlcNAc homeostasis activate the wild type p53 pathway in ovarian cancer cells, and OGA inhibition has the potential as an adjuvant treatment for ovarian carcinoma. PMID:27402830
Inhibition of Mdm2 Sensitizes Human Retinal Pigment Epithelial Cells to Apoptosis

PubMed Central

Ray, Ramesh M.; Chaum, Edward; Johnson, Dianna A.; Johnson, Leonard R.

2011-01-01

Purpose. Because recent studies indicate that blocking the interaction between p53 and Mdm2 results in the nongenotoxic activation of p53, the authors sought to investigate whether the inhibition of p53-Mdm2 binding activates p53 and sensitizes human retinal epithelial cells to apoptosis. Methods. Apoptosis was evaluated by the activation of caspases and DNA fragmentation assays. The Mdm2 antagonist Nutlin-3 was used to dissociate p53 from Mdm2 and, thus, to increase p53 activity. Knockdown of p53 expression was accomplished by using p53 siRNA. Results. ARPE-19 and primary RPE cells expressed high levels of the antiapoptotic proteins Bcl-2 and Bcl-xL. Exposure of these cells to camptothecin (CPT) or TNF-α/ cycloheximide (CHX) failed to induce apoptosis. In contrast, treatment with the Mdm2 antagonist Nutlin-3 in the absence of CPT or TNF-α/CHX increased apoptosis. Activation of p53 in response to Nutlin-3 also increased levels of Noxa, p53-upregulated modulator of apoptosis (PUMA), and Siva-1, decreased expression of Bcl-2 and Bcl-xL, and simultaneously increased caspases-9 and -3 activities and DNA fragmentation. Knockdown of p53 decreased the basal expression of p21Cip1 and Bcl-2, inhibited the Nutlin-3–induced upregulation of Siva-1 and PUMA expression, and consequently inhibited caspase-3 activation. Conclusions. These results indicate that the normally available pool of intracellular p53 is predominantly engaged in the regulation of cell cycle checkpoints by p21Cip1 and does not trigger apoptosis in response to DNA-damaging agents. However, the blockage of p53 binding to Mdm2 frees a pool of p53 that is sufficient, even in the absence of DNA-damaging agents, to increase the expression of proapoptotic targets and to override the resistance of RPE cells to apoptosis. PMID:21345989
Nucleostemin Rejuvenates Cardiac Progenitor Cells and Antagonizes Myocardial Aging

PubMed Central

Hariharan, Nirmala; Quijada, Pearl; Mohsin, Sadia; Joyo, Anya; Samse, Kaitlen; Monsanto, Megan; De La Torre, Andrea; Avitabile, Daniele; Ormachea, Lucia; McGregor, Michael J.; Tsai, Emily J; Sussman, Mark A.

2015-01-01

BACKGROUND Functional decline in stem cell-mediated regeneration contributes to aging associated with cellular senescence in c-kit+ cardiac progenitor cells (CPCs). Clinical implementation of CPC-based therapy with elderly patients would benefit tremendously from understanding molecular characteristics of senescence to antagonize aging. Nucleostemin (NS) is a nucleolar protein regulating stem cell proliferation and pluripotency. OBJECTIVES The goal is to demonstrate that NS preserves characteristics associated with “stemness” in CPCs and antagonizes myocardial senescence and aging. METHODS CPCs isolated from human fetal (FhCPC) and adult failing (AhCPC) hearts, as well as young (YCPC) and old mice (OCPC), were studied for senescence characteristics and NS expression. Heterozygous knockout mice with one functional allele of NS (NS+/−) were used to demonstrate that NS preserves myocardial structure and function and slows characteristics of aging. RESULTS NS expression is decreased in AhCPCs relative to FhCPC, correlating with lowered proliferation potential and shortened telomere length. AhCPC characteristics resemble OCPCs, which have a phenotype induced by NS silencing, resulting in cell flattening, senescence, multinucleated cells, decreased S phase progression, diminished expression of stemness markers and up-regulation of p53 and p16. CPC senescence resulting from NS loss is partially p53 dependent and is rescued by concurrent silencing of p53. Mechanistically, NS induction correlates with Pim-1 kinase-mediated stabilization of c-Myc. Engineering OCPCs and AhCPCs to overexpress NS decreases senescent and multinucleated cells, restores morphology, and antagonizes senescence, thereby preserving phenotypic properties of “stemness.” Early cardiac aging with decline in cardiac function, increase in senescence markers p53 and p16, telomere attrition, and accompanied CPC exhaustion is evident in NS+/− mice. CONCLUSIONS Youthful properties and antagonism of senescence in CPCs and the myocardium is consistent with a role for NS downstream from Pim-1 signaling that enhances cardiac regeneration. PMID:25593054
Novel histone deacetylase inhibitor CG200745 induces clonogenic cell death by modulating acetylation of p53 in cancer cells.

PubMed

Oh, Eun-Taex; Park, Moon-Taek; Choi, Bo-Hwa; Ro, Seonggu; Choi, Eun-Kyung; Jeong, Seong-Yun; Park, Heon Joo

2012-04-01

Histone deacetylase (HDAC) plays an important role in cancer onset and progression. Therefore, inhibition of HDAC offers potential as an effective cancer treatment regimen. CG200745, (E)-N(1)-(3-(dimethylamino)propyl)-N(8)-hydroxy-2-((naphthalene-1-loxy)methyl)oct-2-enediamide, is a novel HDAC inhibitor presently undergoing a phase I clinical trial. Enhancement of p53 acetylation by HDAC inhibitors induces cell cycle arrest, differentiation, and apoptosis in cancer cells. The purpose of the present study was to investigate the role of p53 acetylation in the cancer cell death caused by CG200745. CG200745-induced clonogenic cell death was 2-fold greater in RKO cells expressing wild-type p53 than in p53-deficient RC10.1 cells. CG200745 treatment was also cytotoxic to PC-3 human prostate cancer cells, which express wild-type p53. CG200745 increased acetylation of p53 lysine residues K320, K373, and K382. CG200745 induced the accumulation of p53, promoted p53-dependent transactivation, and enhanced the expression of MDM2 and p21(Waf1/Cip1) proteins, which are encoded by p53 target genes. An examination of CG200745 effects on p53 acetylation using cells transfected with various p53 mutants showed that cells expressing p53 K382R mutants were significantly resistant to CG200745-induced clonogenic cell death compared with wild-type p53 cells. Moreover, p53 transactivation in response to CG200745 was suppressed in all cells carrying mutant forms of p53, especially K382R. Taken together, these results suggest that acetylation of p53 at K382 plays an important role in CG200745-induced p53 transactivation and clonogenic cell death.
Nucleophosmin regulates the stability and transcriptional activity of p53.

PubMed

Colombo, Emanuela; Marine, Jean-Christophe; Danovi, Davide; Falini, Brunangelo; Pelicci, Pier Giuseppe

2002-07-01

Nucleophosmin (NPM) is a ubiquitously expressed nucleolar phosphoprotein that continuously shuttles between the nucleus and cytoplasm. It has been proposed to function in ribosomal protein assembly and transport, and also as a molecular chaperone that prevents proteins from aggregating in the crowded environment of the nucleolus. The NPM gene is involved in several tumour-associated chromosome translocations, which have resulted in the formation of fusion proteins that retain the amino terminus of NPM, including NPM ALK, NPM RAR and NPM MLF1 (ref. 6). It is generally thought that the NPM component is not involved in the transforming potential of these fusion proteins, but instead provides a dimerization interface for the oligomerization and the oncogenic conversion of the various NPM partners (ALK, RAR, MLF1). Here we show that NPM interacts directly with the tumour suppressor p53, regulates the increase in stability and transcriptional activation of p53 after different types of stress, and induces p53-dependent premature senescence on overexpression in diploid fibroblasts. These findings indicate that NPM is a crucial regulator of p53 and suggest that alterations of the NPM function by NPM fusion proteins might lead to deregulation of p53 in tumours.
Space experiment "Rad Gene"-report 1; p53-Dependent gene expression in human cultured cells exposed to space environment

NASA Astrophysics Data System (ADS)

Takahashi, Akihisa; Ohnishi, Takeo; Suzuki, Hiromi; Omori, Katsunori; Seki, Masaya; Hashizume, Toko; Shimazu, Toru; Ishioka, Noriaki

The space environment contains two major biologically significant influences: space radiations and microgravity. A p53 tumor suppressor protein plays a role as a guardian of the genome through the activity of p53-centered signal transduction pathways. The aim of this study was to clarify the biological effects of space radiations, microgravity and a space environment on the gene and protein expression of p53-dependent regulated genes. Space experiments were performed with two human cultured lymphoblastoid cell lines: one cells line (TSCE5) bears a wild-type p53 gene status, and another cells line (WTK1) bears a mutated p53 gene status. Un-der one gravity or microgravity condition, the cells were grown in the cell biology experimental facility (CBEF) of the International Space Station (ISS) for 8 days without experiencing the stress during launching and landing because the cells were frozen during these periods. Ground control samples also were cultured for 8 days in the CBEF on the ground during the same periods as space flight. Gene and protein expression was analyzed by using DNA chip (a 44k whole human genome microarray, Agilent Technologies Inc.) and protein chip (PanoramaTM Ab MicroArray, Sigma-Aldrich Co.), respectively. In addition, we analyzed the gene expression in cultured cells after space flight during 133 days with frozen condition. We report the results and discussion from the viewpoint of the functions of the up-regulated and down-regulated genes after an exposure to space radiations and/or microgravity. The initial goal of this space experiment was completely achieved. It is expected that data from this type of work will be helpful in designing physical protection from the deleterious effects of space radiations during long term stays in space.
Regulation of PI 3-K, PTEN, p53, and mTOR in Malignant and Benign Tumors Deficient in Tuberin

PubMed Central

Yadav, Anamika; Mahimainathan, Lenin; Valente, Anthony J.

2011-01-01

The tuberous sclerosis complex (TSC) is caused by mutation in either of 2 tumor suppressor genes, TSC-1 (encodes hamartin) and TSC-2 (encodes tuberin). In humans, deficiency in TSC1/2 is associated with benign tumors in many organs, including renal angiomyolipoma (AML) but rarely renal cell carcinoma (RCC). In contrast, deficiency of TSC function in the Eker rat is associated with RCC. Here, we have investigated the activity of PI 3-K and the expression of PTEN, p53, tuberin, p-mTOR, and p-p70S6K in both Eker rat RCC and human renal AML. Compared to normal tissue, increased PI 3-K activity was detected in RCC of Eker rats but not in human AML tissue. In contrast, PTEN was highly expressed in AML but significantly reduced in the renal tumors of Eker rats. Phosphorylation on Ser2448 of mTOR and Thr389 of p70S6K were significantly increased in both RCC and AML compared to matching control tissue. Total tuberin was significantly decreased in AML while completely lost in RCC of Eker rats. Our data also show that while p53 protein expression is lost in rat RCC, it was highly elevated in AML. These novel data provide evidence that loss of TSC-2, PTEN, and p53 as well as activation of PI 3-K and mTOR is associated with kidney cancer in the Eker rat, while sustained expression of TSC-2, PTEN, and p53 may prevent progression of kidney cancer in TSC patients. PMID:22737271
p53-regulated autophagy is controlled by glycolysis and determines cell fate

PubMed Central

Duan, Lei; Perez, Ricardo E.; Davaadelger, Batzaya; Dedkova, Elena N.; Blatter, Lothar A.; Maki, Carl G.

2015-01-01

The tumor suppressor p53 regulates downstream targets that determine cell fate. Canonical p53 functions include inducing apoptosis, growth arrest, and senescence. Non-canonical p53 functions include its ability to promote or inhibit autophagy and its ability to regulate metabolism. The extent to which autophagy and/or metabolic regulation determines cell fate by p53 is unclear. To address this, we compared cells resistant or sensitive to apoptosis by the p53 activator Nutlin-3a. In resistant cells, glycolysis was maintained upon Nutlin-3a treatment, and activated p53 promoted prosurvival autophagy. In contrast, in apoptosis sensitive cells activated p53 increased superoxide levels and inhibited glycolysis through repression of glycolytic pathway genes. Glycolysis inhibition and increased superoxide inhibited autophagy by repressing ATG genes essential for autophagic vesicle maturation. Inhibiting glycolysis increased superoxide and blocked autophagy in apoptosis-resistant cells, causing p62-dependent caspase-8 activation. Finally, treatment with 2-DG or the autophagy inhibitors chloroquine or bafilomycin A1 sensitized resistant cells to Nutlin-3a-induced apoptosis. Together, these findings reveal novel links between glycolysis and autophagy that determine apoptosis-sensitivity in response to p53. Specifically, the findings indicate 1) that glycolysis plays an essential role in autophagy by limiting superoxide levels and maintaining expression of ATG genes required for autophagic vesicle maturation, 2) that p53 can promote or inhibit autophagy depending on the status of glycolysis, and 3) that inhibiting protective autophagy can expand the breadth of cells susceptible to Nutlin-3a induced apoptosis. PMID:26337205
Sirt1 overexpression suppresses fluoride-induced p53 acetylation to alleviate fluoride toxicity in ameloblasts responsible for enamel formation.

PubMed

Suzuki, Maiko; Ikeda, Atsushi; Bartlett, John D

2018-03-01

Low-dose fluoride is an effective caries prophylactic, but high-dose fluoride is an environmental health hazard that causes skeletal and dental fluorosis. Treatments to prevent fluorosis and the molecular pathways responsive to fluoride exposure remain to be elucidated. Previously we showed that fluoride activates SIRT1 as an adaptive response to protect cells. Here, we demonstrate that fluoride induced p53 acetylation (Ac-p53) [Lys379], which is a SIRT1 deacetylation target, in ameloblast-derived LS8 cells in vitro and in enamel organ in vivo. Here we assessed SIRT1 function on fluoride-induced Ac-p53 formation using CRISPR/Cas9-mediated Sirt1 knockout (LS8 Sirt/KO ) cells or CRISPR/dCas9/SAM-mediated Sirt1 overexpressing (LS8 Sirt1/over ) cells. NaF (5 mM) induced Ac-p53 formation and increased cell cycle arrest via Cdkn1a/p21 expression in Wild-type (WT) cells. However, fluoride-induced Ac-p53 was suppressed by the SIRT1 activator resveratrol (50 µM). Without fluoride, Ac-p53 persisted in LS8 Sirt/KO cells, whereas it decreased in LS8 Sirt1/over . Fluoride-induced Ac-p53 formation was also suppressed in LS8 Sirt1/over cells. Compared to WT cells, fluoride-induced Cdkn1a/p21 expression was elevated in LS8 Sirt/KO and these cells were more susceptible to fluoride-induced growth inhibition. In contrast, LS8 Sirt1/over cells were significantly more resistant. In addition, fluoride-induced cytochrome-c release and caspase-3 activation were suppressed in LS8 Sirt1/over cells. Fluoride induced expression of the DNA double strand break marker γH2AX in WT cells and this was augmented in LS8 Sirt1/KO cells, but was attenuated in LS8 Sirt1/over cells. Our results suggest that SIRT1 deacetylates Ac-p53 to mitigate fluoride-induced cell growth inhibition, mitochondrial damage, DNA damage and apoptosis. This is the first report implicating Ac-p53 in fluoride toxicity.
TP53 Mutation Status of Tubo-ovarian and Peritoneal High-grade Serous Carcinoma with a Wild-type p53 Immunostaining Pattern.

PubMed

Na, Kiyong; Sung, Ji-Youn; Kim, Hyun-Soo

2017-12-01

Diffuse and strong nuclear p53 immunoreactivity and a complete lack of p53 expression are regarded as indicative of missense and nonsense mutations, respectively, of the TP53 gene. Tubo-ovarian and peritoneal high-grade serous carcinoma (HGSC) is characterized by aberrant p53 expression induced by a TP53 mutation. However, our experience with some HGSC cases with a wild-type p53 immunostaining pattern led us to comprehensively review previous cases and investigate the TP53 mutational status of the exceptional cases. We analyzed the immunophenotype of 153 cases of HGSC and performed TP53 gene sequencing analysis in those with a wild-type p53 immunostaining pattern. Immunostaining revealed that 109 (71.3%) cases displayed diffuse and strong p53 expression (missense mutation pattern), while 39 (25.5%) had no p53 expression (nonsense mutation pattern). The remaining five cases of HGSC showed a wild-type p53 immunostaining pattern. Direct sequencing analysis revealed that three of these cases harbored nonsense TP53 mutations and two had novel splice site deletions. TP53 mutation is almost invariably present in HGSC, and p53 immunostaining can be used as a surrogate marker of TP53 mutation. In cases with a wild-type p53 immunostaining pattern, direct sequencing for TP53 mutational status can be helpful to confirm the presence of a TP53 mutation. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
Caspase-2-mediated cleavage of Mdm2 creates p53-induced positive feedback loop

PubMed Central

Oliver, Trudy G.; Meylan, Etienne; Chang, Gregory P.; Xue, Wen; Burke, James R.; Humpton, Timothy J.; Hubbard, Diana; Bhutkar, Arjun; Jacks, Tyler

2011-01-01

SUMMARY Caspase-2 is an evolutionarily conserved caspase, yet its biological function and cleavage targets are poorly understood. Caspase-2 is activated by the p53 target gene product PIDD (also known as LRDD) in a complex called the Caspase-2-PIDDosome. We show that PIDD expression promotes growth arrest and chemotherapy resistance by a mechanism that depends on Caspase-2 and wild-type p53. PIDD-induced Caspase-2 directly cleaves the E3 ubiquitin ligase Mdm2 at Asp 367, leading to loss of the C-terminal RING domain responsible for p53 ubiquitination. As a consequence, N-terminally truncated Mdm2 binds p53 and promotes its stability. Upon DNA damage, p53 induction of the Caspase-2-PIDDosome creates a positive feedback loop that inhibits Mdm2 and reinforces p53 stability and activity, contributing to cell survival and drug resistance. These data establish Mdm2 as a cleavage target of Caspase-2 and provide insight into a mechanism of Mdm2 inhibition that impacts p53 dynamics upon genotoxic stress. PMID:21726810

Dynamics of Delayed p53 Mutations in Mice Given Whole-Body Irradiation at 8 Weeks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okazaki, Ryuji, E-mail: ryuji-o@med.uoeh-u.ac.j; Ootsuyama, Akira; Kakihara, Hiroyo

2011-01-01

Purpose: Ionizing irradiation might induce delayed genotoxic effects in a p53-dependent manner. However, a few reports have shown a p53 mutation as a delayed effect of radiation. In this study, we investigated the p53 gene mutation by the translocation frequency in chromosome 11, loss of p53 alleles, p53 gene methylation, p53 nucleotide sequence, and p53 protein expression/phosphorylation in p53{sup +/+} and p53{sup +/-} mice after irradiation at a young age. Methods and Materials: p53{sup +/+} and p53{sup +/-} mice were exposed to 3 Gy of whole-body irradiation at 8 weeks of age. Chromosome instability was evaluated by fluorescence in situmore » hybridization analysis. p53 allele loss was evaluated by polymerase chain reaction, and p53 methylation was evaluated by methylation-specific polymerase chain reaction. p53 sequence analysis was performed. p53 protein expression was evaluated by Western blotting. Results: The translocation frequency in chromosome 11 showed a delayed increase after irradiation. In old irradiated mice, the number of mice that showed p53 allele loss and p53 methylation increased compared to these numbers in old non-irradiated mice. In two old irradiated p53{sup +/-} mice, the p53 sequence showed heteromutation. In old irradiated mice, the p53 and phospho-p53 protein expressions decreased compared to old non-irradiated mice. Conclusion: We concluded that irradiation at a young age induced delayed p53 mutations and p53 protein suppression.« less
Alcohol alters hepatic FoxO1, p53, and mitochondrial SIRT5 deacetylation function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lieber, Charles S.; Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029; Leo, Maria Anna

2008-08-22

Chronic alcohol consumption affects the gene expression of a NAD-dependent deacetylase Sirtuis 1 (SIRT1) and the peroxisome proliferator-activated receptor-{gamma} coactivator1{alpha} (PGC-1{alpha}). Our aim was to verify that it also alters the forkhead (FoxO1) and p53 transcription factor proteins, critical in the hepatic response to oxidative stress and regulated by SIRT1 through its deacetylating capacity. Accordingly, rats were pair-fed the Lieber-DeCarli alcohol-containing liquid diets for 28 days. Alcohol increased hepatic mRNA expression of FoxO1 (p = 0.003) and p53 (p = 0.001) while corresponding protein levels remained unchanged. However phospho-FoxO1 and phospho-Akt (protein kinase) were both decreased by alcohol consumption (pmore » = 0.04 and p = 0.02, respectively) while hepatic p53 was found hyperacetylated (p = 0.017). Furthermore, mitochondrial SIRT5 was reduced (p = 0.0025), and PGC-1{alpha} hyperacetylated (p = 0.027), establishing their role in protein modification. Thus, alcohol consumption disrupts nuclear-mitochondrial interactions by post-translation protein modifications, which contribute to alteration of mitochondrial biogenesis through the newly discovered reduction of SIRT5.« less
Expression of p53 and Bcl-xL as predictive markers for larynx preservation in advanced laryngeal cancer

PubMed Central

Kumar, Bhavna; Cordell, Kitrina G.; D’Silva, Nisha; Prince, Mark E.; Adams, Meredith E.; Fisher, Susan G.; Wolf, Gregory T.; Carey, Thomas E.; Bradford, Carol R.

2012-01-01

Objective To assess tumor markers in advanced laryngeal cancer. Design Marker expression and clinical outcome. Setting Laboratory. Patients Pretreatment tumor biopsies were analyzed from patients enrolled in the Department of Veterans Affairs laryngeal cancer trial. Main Outcome Measures Expression of p53 and Bcl-xL in pretreatment biopsies was assessed for correlation with chemotherapy response, laryngeal preservation, and survival. Results Higher rates of larynx preservation were observed in patients whose tumors expressed p53 versus those that did not (73% versus 53%, p = 0.0304). Higher rates of larynx preservation were also observed in patients whose tumors expressed low levels of Bcl-xL versus those that expressed high levels (90% versus 60%, p = 0.02). Patients were then categorized into 3 risk groups (low, intermediate and high risk) based on their tumor p53 and Bcl-xL expression status. We observed that patients whose tumors had the high risk biomarker profile (low p53 and high Bcl-xL) were less likely to preserve their larynx than patients whose tumors had the intermediate risk (high p53 and low or high Bcl-xL) or low risk (low p53 and low Bcl-xL) biomarker profile. The larynx preservation rates were 100%, 76% and 54% for the low, intermediate and high risk groups respectively (Fisher exact 0.039). Conclusions Tumor expression of p53 and Bcl-xL is a strong predictor of successful organ preservation in patients treated with induction chemotherapy followed by radiation in responding tumors. PMID:18427001
p53 Mediates Vast Gene Expression Changes That Contribute to Poor Chemotherapeutic Response in a Mouse Model of Breast Cancer.

PubMed

Tonnessen-Murray, Crystal; Ungerleider, Nathan A; Rao, Sonia G; Wasylishen, Amanda R; Frey, Wesley D; Jackson, James G

2018-05-28

p53 is a transcription factor that regulates expression of genes involved in cell cycle arrest, senescence, and apoptosis. TP53 harbors mutations that inactivate its transcriptional activity in roughly 30% of breast cancers, and these tumors are much more likely to undergo a pathological complete response to chemotherapy. Thus, the gene expression program activated by wild-type p53 contributes to a poor response. We used an in vivo genetic model system to comprehensively define the p53- and p21-dependent genes and pathways modulated in tumors following doxorubicin treatment. We identified genes differentially expressed in spontaneous mammary tumors harvested from treated MMTV-Wnt1 mice that respond poorly (Trp53+/+) or favorably (Trp53-null) and those that lack the critical senescence/arrest p53 target gene Cdkn1a. Trp53 wild-type tumors differentially expressed nearly 10-fold more genes than Trp53-null tumors after treatment. Pathway analyses showed that genes involved in cell cycle, senescence, and inflammation were enriched in treated Trp53 wild-type tumors; however, no genes/pathways were identified that adequately explain the superior cell death/tumor regression observed in Trp53-null tumors. Cdkn1a-null tumors that retained arrest capacity (responded poorly) and those that proliferated (responded well) after treatment had remarkably different gene regulation. For instance, Cdkn1a-null tumors that arrested upregulated Cdkn2a (p16), suggesting an alternative, p21-independent route to arrest. Live animal imaging of longitudinal gene expression of a senescence/inflammation gene reporter in Trp53+/+ tumors showed induction during and after chemotherapy treatment, while tumors were arrested, but expression rapidly diminished immediately upon relapse. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
The p53 Isoform Δ133p53β Promotes Cancer Stem Cell Potential

PubMed Central

Arsic, Nikola; Gadea, Gilles; Lagerqvist, E. Louise; Busson, Muriel; Cahuzac, Nathalie; Brock, Carsten; Hollande, Frederic; Gire, Veronique; Pannequin, Julie; Roux, Pierre

2015-01-01

Summary Cancer stem cells (CSC) are responsible for cancer chemoresistance and metastasis formation. Here we report that Δ133p53β, a TP53 splice variant, enhanced cancer cell stemness in MCF-7 breast cancer cells, while its depletion reduced it. Δ133p53β stimulated the expression of the key pluripotency factors SOX2, OCT3/4, and NANOG. Similarly, in highly metastatic breast cancer cells, aggressiveness was coupled with enhanced CSC potential and Δ133p53β expression. Like in MCF-7 cells, SOX2, OCT3/4, and NANOG expression were positively regulated by Δ133p53β in these cells. Finally, treatment of MCF-7 cells with etoposide, a cytotoxic anti-cancer drug, increased CSC formation and SOX2, OCT3/4, and NANOG expression via Δ133p53, thus potentially increasing the risk of cancer recurrence. Our findings show that Δ133p53β supports CSC potential. Moreover, they indicate that the TP53 gene, which is considered a major tumor suppressor gene, also acts as an oncogene via the Δ133p53β isoform. PMID:25754205
Critical functions of RhoB in support of glioblastoma tumorigenesis

PubMed Central

Ma, Yufang; Gong, Yuanying; Cheng, Zhixiang; Loganathan, Sudan; Kao, Crystal; Sarkaria, Jann N.; Abel, Ty W.; Wang, Jialiang

2015-01-01

Background RhoB is a member of the Rho small GTPase family that regulates cytoskeletal dynamics and vesicle trafficking. The RhoB homologs, RhoA and RhoC, have been shown to promote cancer progression and metastasis. In contrast, the functions of RhoB in human cancers are context dependent. Although expression of RhoB inversely correlates with disease progression in several epithelial cancers, recent data suggest that RhoB may support malignant phenotypes in certain cancer types. Methods We assessed RhoB protein levels in glioma surgical specimens and patient-derived xenografts. The roles of RhoB in glioblastoma were determined by loss-of-function and gain-of-function assays in vitro and in vivo. The impact on p53 and STAT3 signaling was investigated. Results RhoB expression was similar in tumor specimens compared with normal neural tissues obtained from epilepsy surgery. RhoB was expressed in the vast majority of xenograft tumors and spheroid cultures. Knockdown of RhoB induced cell-cycle arrest and apoptosis and compromised in vivo tumorigenic potential. However, overexpression of wild-type RhoB or a constitutively active mutant (RhoB-V14) did not significantly affect cell growth, which suggests that RhoB is not a rate-limiting oncogenic factor and is consistent with the scarcity of RhoB mutations in human cancer. Knockdown of RhoB reduced basal STAT3 activity and impaired cytokine-induced STAT3 activation. In glioblastoma tumors retaining wild-type p53, depletion of RhoB also activated p53 and induced expression of p21CIP1/WAF1. Conclusions Our data suggest that RhoB belongs to an emerging class of “nononcogene addiction” factors that are essential for maintenance of malignant phenotypes in human cancers. PMID:25216671
Immunohistochemical expression of p53 and its clinicopathological correlation with modified Anneroth's histological grading system.

PubMed

Dave, Kajal V; Chalishazar, Monali; Dave, Vishal R; Panja, Pritam; Singh, Manisha; Modi, Tapan G

2016-01-01

Oral squamous cell carcinoma (OSCC) is an epithelial neoplasm generally beginning as focal overgrowth of altered stem cells near the basement membrane, moving upward and laterally, replacing the normal epithelium. Histopathological grading has been used for many decades in an attempt to predict the clinical behavior of oral squamous cell carcinoma. In the present study, Forty biopsies were studied for histological grading and p53 expression. The p53 expression was studied in relation to clinical parameters such as age, sex of patient and site of tumors. Relation between histological grade of malignancy and p53 protein expression was analysed. All cases were classified according to Anneroth's histological malignancy grading system (1987). 40 cases of OSCC were assessed for clinical parameters, Anneroth's histological grading and immunohistochemically stained with p53 protien. The results obtained were analyzed using Spearman's Co-relation. The positive expression of p53 was found in 62% of carcinomas studied. Positivity of p53 showed correlation with histological grade of malignancy and with individual parameters like degree of keratinization, nuclear polymorphism, number of mitoses and lymphoplasmacytic infiltration while showed a negative correlation with pattern of invasion. Our study showed a significant correlation between parameters of tumor cell population, lymphoplasmacytic infiltration and p53 expression. A significant association between high grade of malignancy and p53 overexpression and insignificant correlation of p53 with age, sex of the patient and site of the tumor was found.
Synergistic targeting of malignant pleural mesothelioma cells by MDM2 inhibitors and TRAIL agonists

PubMed Central

Urso, Loredana; Biasini, Lorena; Zago, Giulia; Calabrese, Fiorella; Conte, Pier Franco; Ciminale, Vincenzo; Pasello, Giulia

2017-01-01

Malignant Pleural Mesothelioma (MPM) is a chemoresistant tumor characterized by low rate of p53 mutation and upregulation of Murine Double Minute 2 (MDM2), suggesting that it may be effectively targeted using MDM2 inhibitors. In the present study, we investigated the anticancer activity of the MDM2 inhibitors Nutlin 3a (in vitro) and RG7112 (in vivo), as single agents or in combination with rhTRAIL. In vitro studies were performed using MPM cell lines derived from epithelioid (ZL55, M14K), biphasic (MSTO211H) and sarcomatoid (ZL34) MPMs. In vivo studies were conducted on a sarcomatoid MPM mouse model. In all the cell lines tested (with the exception of ZL55, which carries a biallelic loss-of-function mutation of p53), Nutlin 3a enhanced p21, MDM2 and DR5 expression, and decreased survivin expression. These changes were associated to cell cycle arrest but not to a significant induction of apoptosis. A synergistic pro-apoptotic effect was obtained through the association of rhTRAIL in all the cell lines harboring functional p53. This synergistic interaction of MDM2 inhibitor and TRAIL agonist was confirmed using a mouse preclinical model. Our results suggest that the combined targeting of MDM2 and TRAIL might provide a novel therapeutic option for treatment of MPM patients, particularly in the case of sarcomatoid MPM with MDM2 overexpression and functional inactivation of wild-type p53. PMID:28562336
TP53 mutations, expression and interaction networks in human cancers

PubMed Central

Wang, Xiaosheng; Sun, Qingrong

2017-01-01

Although the associations of p53 dysfunction, p53 interaction networks and oncogenesis have been widely explored, a systematic analysis of TP53 mutations and its related interaction networks in various types of human cancers is lacking. Our study explored the associations of TP53 mutations, gene expression, clinical outcomes, and TP53 interaction networks across 33 cancer types using data from The Cancer Genome Atlas (TCGA). We show that TP53 is the most frequently mutated gene in a number of cancers, and its mutations appear to be early events in cancer initiation. We identified genes potentially repressed by p53, and genes whose expression correlates significantly with TP53 expression. These gene products may be especially important nodes in p53 interaction networks in human cancers. This study shows that while TP53-truncating mutations often result in decreased TP53 expression, other non-truncating TP53 mutations result in increased TP53 expression in some cancers. Survival analyses in a number of cancers show that patients with TP53 mutations are more likely to have worse prognoses than TP53-wildtype patients, and that elevated TP53 expression often leads to poor clinical outcomes. We identified a set of candidate synthetic lethal (SL) genes for TP53, and validated some of these SL interactions using data from the Cancer Cell Line Project. These predicted SL genes are promising candidates for experimental validation and the development of personalized therapeutics for patients with TP53-mutated cancers. PMID:27880943
TP53 mutations, expression and interaction networks in human cancers.

PubMed

Wang, Xiaosheng; Sun, Qingrong

2017-01-03

Although the associations of p53 dysfunction, p53 interaction networks and oncogenesis have been widely explored, a systematic analysis of TP53 mutations and its related interaction networks in various types of human cancers is lacking. Our study explored the associations of TP53 mutations, gene expression, clinical outcomes, and TP53 interaction networks across 33 cancer types using data from The Cancer Genome Atlas (TCGA). We show that TP53 is the most frequently mutated gene in a number of cancers, and its mutations appear to be early events in cancer initiation. We identified genes potentially repressed by p53, and genes whose expression correlates significantly with TP53 expression. These gene products may be especially important nodes in p53 interaction networks in human cancers. This study shows that while TP53-truncating mutations often result in decreased TP53 expression, other non-truncating TP53 mutations result in increased TP53 expression in some cancers. Survival analyses in a number of cancers show that patients with TP53 mutations are more likely to have worse prognoses than TP53-wildtype patients, and that elevated TP53 expression often leads to poor clinical outcomes. We identified a set of candidate synthetic lethal (SL) genes for TP53, and validated some of these SL interactions using data from the Cancer Cell Line Project. These predicted SL genes are promising candidates for experimental validation and the development of personalized therapeutics for patients with TP53-mutated cancers.
miR-300 promotes proliferation and EMT-mediated colorectal cancer migration and invasion by targeting p53.

PubMed

Wang, Lin; Yu, Peiwu

2016-12-01

p53 mutations in tumors can induce the loss of wild-type tumor-suppressing p53 function, which results in the increase in proliferation, migration and invasion ability in cancer cells. Studies have shown that the expression of p53 is regulated by several microRNAs (miRNAs). In the present study, we found that miR-300 and p53 were significantly increased in colorectal cancer (CRC) tissues when compared with levels noted in adjacent colorectal tissues. Both miR-300 and p53 were significantly correlated with lymphatic metastasis and TNM stage. Both miR-300 and p53 promoted CRC cell (SW480 and HT29) proliferation, migration, and invasion, respectively, in vitro. In addition, we found that miR-300 is a direct positive regulator of p53 through binding to the binding site in the 3'UTR of the p53 gene in human CRC cells. Moreover, both miR-300 and p53 induced CRC cell epithelial‑mesenchymal transition (EMT) respectively. Taken together, we demonstrated that miR-300 promoted proliferation and EMT-mediated CRC migration and invasion by targeting p53. These findings provide a new theoretical basis and potential therapeutic targets, and thus lays the foundation for exploring the pathogenesis of CRC.
Curcumin induces permanent growth arrest of human colon cancer cells: link between senescence and autophagy.

PubMed

Mosieniak, Grazyna; Adamowicz, Marek; Alster, Olga; Jaskowiak, Hubert; Szczepankiewicz, Andrzej A; Wilczynski, Grzegorz M; Ciechomska, Iwona A; Sikora, Ewa

2012-06-01

Curcumin, a natural polyphenol derived from the rhizome of Curcuma longa, is a potent anticancer agent, which restricts tumor cell growth both in vitro and in vivo. Thus far curcumin was shown to induce death of cancer cells. This study reports the induction of cellular senescence of human colon cancer cells HCT116 upon curcumin treatment. The SA-β-galactosidase activation was observed both in p53+/+ and p53-/- cells, however the latter ones were less sensitive to the prosenescent activity of curcumin. Upregulation of p53 and p21 proteins was observed in p53+/+ HCT116, while p53-independent induction of p21 was noticed in p53-/- HCT116. Moreover, the senescence of HCT116 cells was accompanied by autophagy, that was confirmed by electron microscopy observations of autophagosomes in the curcumin-treated cells as well as LC3-II expression, punctue staining of LC3 and increased content of acidic vacuoles. Inhibition of autophagy, due to the diminished expression of ATG5 by RNAi decreased the number of senescent cells induced by curcumin, but did not lead to increased cell death. Altogether, we demonstrated a new antitumor activity of curcumin leading to cancer cell senescence and revealed the presence of a functional link between senescence and autophagy in curcumin-treated cells. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
The induction of thioredoxin-1 by epinephrine withdraws stress via interaction with β-arrestin-1

PubMed Central

Jia, Jin-Jing; Zeng, Xian-Si; Zhou, Xiao-Shuang; Li, Ye; Bai, Jie

2014-01-01

Stress regulates a panel of important physiological functions and disease states. Epinephrine is produced under stresses threaten to homeostasis. Thioredoxin-1(Trx-1) is a redox regulating protein which is induced to resist stresses and related with various diseases. Thus, it is important to examine whether Trx-1 is induced by epinephrine and to understand the underlying molecular mechanisms that Trx-1 modulates epinephrine stress. Here, we show that the expression of Trx-1 was induced by epinephrine via β-adrenergic receptor/Cyclic AMP/protein kinase A (PKA) signaling pathway in PC12 cells. The down-regulation of Trx-1 by siRNA aggravated accumulation of γ-H2AX and further decreased expression of p53 by epinephrine. Accordingly, Trx-1 overexpression alleviated accumulation of γ-H2AX and restored the expressions of p53 and C/EBP homologous protein (CHOP) in the cortex, hippocampus and thymus of mice. Moreover, Trx-1 overexpression reduced the malondialdehyde concentration by epinephrine. We further explored the mechanism on p53 and γ-H2AX regulated by Trx-1. We found that overexpression of Trx-1 suppressed β-arrestin-1 expression through interaction with β-arrestin-1. Consequently, the downregulation of β-arrestin-1 suppressed the cell viability and the expressions of γ-H2AX and cyclin D1, and increased p53 expression. Taken together, our data suggest that Trx-1/β-arrestin-1 interaction may represent a novel endogenous mechanism on protecting against stress. PMID:25486571
Assessment of mdm2 Alterations on p53 Expression in Breast Cancer

DTIC Science & Technology

2000-10-01

Figure 2. Schematic Comparison of mdm2 with PCR Products of Various Sizes. nuclear localization signal I p53 binding site X acidic domain zinc...susceptibility gene isolated by controlled homozygous functional knockout of allelic loci in mammalian cells. Cell. 85: 319-329, 1996. 36. Li, L., Li, X ...twelve years. Chinese Journal of Parasitology and Parasitic Diseases 10: 112-114, 1992. 7. Gao DQ, Cansesaa L, Mouradian MM, Jose P. Dopamine D2-long
Influence of p53 status on the effects of boron neutron capture therapy in glioblastoma.

PubMed

Seki, Keiko; Kinashi, Yuko; Takahashi, Sentaro

2015-01-01

The tumor suppressor gene p53 is mutated in glioblastoma. We studied the relationship between the p53 gene and the biological effects of boron neutron capture therapy (BNCT). The human glioblastoma cells; A172, expressing wild-type p53, and T98G, with mutant p53, were irradiated by the Kyoto University Research Reactor (KUR). The biological effects after neutron irradiation were evaluated by the cell killing effect, 53BP1 foci assay and apoptosis induction. The survival-fraction data revealed that A172 was more radiosensitive than T98G, but the difference was reduced when boronophenylalanine (BPA) was present. Both cell lines exhibited similar numbers of foci, suggesting that the initial levels of DNA damage did not depend on p53 function. Detection of apoptosis revealed a lower rate of apoptosis in the T98G. BNCT causes cell death in glioblastoma cells, regardless of p53 mutation status. In T98G cells, cell killing and apoptosis occurred effectively following BNCT. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.
Thymidilate synthase and p53 primary tumour expression as predictive factors for advanced colorectal cancer patients.

PubMed

Paradiso, A; Simone, G; Petroni, S; Leone, B; Vallejo, C; Lacava, J; Romero, A; Machiavelli, M; De Lena, M; Allegra, C J; Johnston, P G

2000-02-01

The purpose of this work was to analyse the ability of p53 and thymidilate synthase (TS) primary tumour expression to retrospectively predict clinical response to chemotherapy and long-term prognosis in patients with advanced colorectal cancers homogeneously treated by methotrexate (MTX)-modulated-5-fluorouracil (5-FU-FA). A total of 108 advanced colorectal cancer patients entered the present retrospective study. Immunohistochemical p53 (pAb 1801 mAb) and TS (TS106 mAb) expression on formalin-fixed paraffin-embedded primary tumour specimens was related to probability of clinical response to chemotherapy, time to progression and overall survival. p53 was expressed in 53/108 (49%) tumours, while 54/108 (50%) showed TS immunostaining. No relationship was demonstrated between p53 positivity and clinical response to chemotherapy (objective response (OR): 20% vs 23%, in p53+ and p53- cases respectively) or overall survival. Percent of OR was significantly higher in TS-negative with respect to TS-positive tumours (30% vs 15% respectively; P < 0.04); simultaneous analysis of TS and p53 indicated 7% OR for p53-positive/TS-positive tumours vs 46% for p53-positive/TS-negative tumours (P < 0.03). Logistic regression analysis confirmed a significant association between TS tumour status and clinical response to chemotherapy (hazard ratio (HR): 2.91; 95% confidence interval (CI) 8.34-1.01; two-sided P < 0.05). A multivariate analysis of overall survival showed that only a small number of metastatic sites was statistically relevant (HR 1.89; 95% CI 2.85-1.26; two-sided P < 0.03). Our study suggests that immunohistochemical expression of p53 and TS could assist the clinician in predicting response of colorectal cancer patients to modulated MTX-5-FU therapy.
The novel tumor suppressor p33ING2 enhances UVB-induced apoptosis in human melanoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, M.Y.; Ng, Kin Cheung P.; Li Gang

The roles of p33ING2 as a tumor suppressor candidate have been shown through regulation of gene transcription, induction of cell cycle arrest, and apoptosis. As p33ING2 shares 58.9% homology with p33ING1b, we hypothesized that p33ING2 shares functional similarities with p33ING1b. We previously found that p33ING1b cooperates with p53 to enhance UVB-induced apoptosis. Here, we report that overexpression of p33ING2 enhanced apoptosis in UVB-irradiated and non-irradiated melanoma MMRU cells. We demonstrate that enhancement of apoptosis by p33ING2 requires the presence of functional p53. Furthermore, we found that overexpression of p33ING2 significantly downregulated the expression of Bcl-2 after UVB irradiation, resulting inmore » an increased Bax/Bcl-2 ratio. Moreover, we found that p33ING2 promoted Bax translocation to mitochondria, altered the mitochondrial membrane potential, and induced cytochrome c release and thus the activation of caspases 9 and 3. In addition, we showed that under non-stress conditions p33ING2 upregulates Fas expression and activates caspase 8. Taken together, we demonstrate that p33ING2 cooperates with p53 to regulate apoptosis via activation of both the mitochondrial/intrinsic and death-receptor/extrinsic apoptotic pathways.« less
Immunohistochemical Analysis of ATRX, IDH1 and p53 in Glioblastoma and Their Correlations with Patient Survival

PubMed Central

2016-01-01

Glioblastoma (GBM) can be classified into molecular subgroups, on the basis of biomarker expression. Here, we classified our cohort of 163 adult GBMs into molecular subgroups according to the expression of proteins encoded by genes of alpha thalassemia/mental retardation syndrome X-linked (ATRX), isocitrate dehydrogenase (IDH) and TP53. We focused on the survival rate of molecular subgroups, depending on each and various combination of these biomarkers. ATRX, IDH1 and p53 protein expression were evaluated immunohistochemically and Kaplan-Meier analysis were carried out in each group. A total of 15.3% of enrolled GBMs demonstrated loss of ATRX expression (ATRX-), 10.4% expressed an aberrant IDH1 R132H protein (IDH1+), and 48.4% exhibited p53 overexpression (p53+). Survival differences were statistically significant when single protein expression or different combinations of expression of these proteins were analyzed. In conclusion, in the case of single protein expression, the patients with each IDH1+, or ATRX-, or p53- GBMs showed better survival than patients with counterparts protein expressed GBMs. In the case of double protein pairs, the patients with ATRX-/p53-, ATRX-/IDH1+, and IDH1+/p53- GBMs revealed better survival than the patients with GBMs with the remained pairs. In the case of triple protein combinations, the patients with ATRX-/p53-/IDH+ showed statistically significant survival gain than the patients with remained combination of proteins-expression status. Therefore, these three biomarkers, individually and as a combination, can stratify GBMs into prognostically relevant subgroups and have strong prognostic values in adult GBMs. PMID:27478330
DOE Office of Scientific and Technical Information (OSTI.GOV)

Simoes, Maria L.; Hockley, Sarah L.; Schwerdtle, Tanja

Aristolochic acid (AA) is the causative agent of urothelial tumours associated with aristolochic acid nephropathy. These tumours contain TP53 mutations and over-express TP53. We compared transcriptional and translational responses of two isogenic HCT116 cell lines, one expressing TP53 (p53-WT) and the other with this gene knocked out (p53-null), to treatment with aristolochic acid I (AAI) (50-100 {mu}M) for 6-48 h. Modulation of 118 genes was observed in p53-WT cells and 123 genes in p53-null cells. Some genes, including INSIG1, EGR1, CAV1, LCN2 and CCNG1, were differentially expressed in the two cell lines. CDKN1A was selectively up-regulated in p53-WT cells, leadingmore » to accumulation of TP53 and CDKN1A. Apoptotic signalling, measured by caspase-3 and -7 activity, was TP53-dependent. Both cell types accumulated in S phase, suggesting that AAI-DNA adducts interfere with DNA replication, independently of TP53 status. The oncogene MYC, frequently over-expressed in urothelial tumours, was up-regulated by AAI, whereas FOS was down-regulated. Observed modulation of genes involved in endocytosis, e.g. RAB5A, may be relevant to the known inhibition of receptor-mediated endocytosis, an early sign of AA-mediated proximal tubule injury. AAI-DNA adduct formation was significantly greater in p53-WT cells than in p53-null cells. Collectively, phenotypic anchoring of the AAI-induced expression profiles to DNA adduct formation, cell-cycle parameters, TP53 expression and apoptosis identified several genes linked to these biological outcomes, some of which are TP53-dependent. These results strengthen the importance of TP53 in AA-induced cancer, and indicate that other alterations, e.g. to MYC oncogenic pathways, may also contribute.« less
Endothelial cell senescence with aging in healthy humans: prevention by habitual exercise and relation to vascular endothelial function.

PubMed

Rossman, Matthew J; Kaplon, Rachelle E; Hill, Sierra D; McNamara, Molly N; Santos-Parker, Jessica R; Pierce, Gary L; Seals, Douglas R; Donato, Anthony J

2017-11-01

Cellular senescence is emerging as a key mechanism of age-related vascular endothelial dysfunction, but evidence in healthy humans is lacking. Moreover, the influence of lifestyle factors such as habitual exercise on endothelial cell (EC) senescence is unknown. We tested the hypothesis that EC senescence increases with sedentary, but not physically active, aging and is associated with vascular endothelial dysfunction. Protein expression (quantitative immunofluorescence) of p53, a transcription factor related to increased cellular senescence, and the cyclin-dependent kinase inhibitors p21 and p16 were 116%, 119%, and 128% greater (all P < 0.05), respectively, in ECs obtained from antecubital veins of older sedentary (60 ± 1 yr, n = 12) versus young sedentary (22 ± 1 yr, n = 9) adults. These age-related differences were not present (all P > 0.05) in venous ECs from older exercising adults (57 ± 1 yr, n = 13). Furthermore, venous EC protein levels of p53 ( r = -0.49, P = 0.003), p21 ( r = -0.38, P = 0.03), and p16 ( r = -0.58, P = 0.002) were inversely associated with vascular endothelial function (brachial artery flow-mediated dilation). Similarly, protein expression of p53 and p21 was 26% and 23% higher (both P < 0.05), respectively, in ECs sampled from brachial arteries of healthy older sedentary (63 ± 1 yr, n = 18) versus young sedentary (25 ± 1 yr, n = 9) adults; age-related changes in arterial EC p53 and p21 expression were not observed ( P > 0.05) in older habitually exercising adults (59 ± 1 yr, n = 14). These data indicate that EC senescence is associated with sedentary aging and is linked to endothelial dysfunction. Moreover, these data suggest that prevention of EC senescence may be one mechanism by which aerobic exercise protects against endothelial dysfunction with age. NEW & NOTEWORTHY Our study provides novel evidence in humans of increased endothelial cell senescence with sedentary aging, which is associated with impaired vascular endothelial function. Furthermore, our data suggest an absence of age-related increases in endothelial cell senescence in older exercising adults, which is linked with preserved vascular endothelial function. Copyright © 2017 the American Physiological Society.

Markers of potential malignancy in chronic hyperplastic candidiasis.

PubMed

Darling, Mark R; McCord, Christina; Jackson-Boeters, Linda; Copete, Maria

2012-08-01

To examine the presence of markers associated with malignancy, including p53, p21 cyclin-dependent kinase inhibitor 1A, murine double minutes-2, and others, in chronic hyperplastic candidiasis. Immunohistochemical methods were used to examine the expression of p53, murine double minutes-2, p21 cyclin-dependent kinase inhibitor 1A, metallothionein, and proliferating cell nuclear antigen in 42 chronic hyperplastic candidiasis lesions and 11 non-infected control tissues. Terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling was used to examine apoptosis, which was correlated with p53 expression. These markers were measured in lesions of chronic hyperplastic candidiasis that did not show any epithelial dysplasia or histological signs of malignancy. p53 scores were higher in chronic hyperplastic candidiasis than in controls (P = 0.0046). Murine double-minutes 2 levels were not elevated. p21 cyclin-dependent kinase inhibitor 1A was increased in parabasal (P < 0.0001) and basal epithelial cells. Chronic hyperplastic candidiasis lesions showed a similar basal/parabasal metallothionein staining pattern to that seen in normal squamous epithelium. Proliferating cell nuclear antigen was increased (P = 0.0007), as was apoptosis (P = 0.0033). Increased p53 in oral chronic hyperplastic candidiasis suggests an increased potential for malignant change in the epithelium, above that of normal tissues. Further functional investigation is required, as well as clinical follow-up studies. © 2012 Blackwell Publishing Asia Pty Ltd.
Nanotized PPARα Overexpression Targeted to Hypertrophied Myocardium Improves Cardiac Function by Attenuating the p53-GSK3β-Mediated Mitochondrial Death Pathway.

PubMed

Rana, Santanu; Datta, Ritwik; Chaudhuri, Ratul Datta; Chatterjee, Emeli; Chawla-Sarkar, Mamta; Sarkar, Sagartirtha

2018-05-09

Metabolic remodeling of cardiac muscles during pathological hypertrophy is characterized by downregulation of fatty acid oxidation (FAO) regulator, peroxisome proliferator-activated receptor alpha (PPARα). Thereby, we hypothesized that a cardiac-specific induction of PPARα might restore the FAO-related protein expression and resultant energy deficit. In the present study, consequences of PPARα augmentation were evaluated for amelioration of chronic oxidative stress, myocyte apoptosis, and cardiac function during pathological cardiac hypertrophy. Nanotized PPARα overexpression targeted to myocardium was done by a stearic acid-modified carboxymethyl-chitosan (CMC) conjugated to a 20-mer myocyte-targeted peptide (CMCP). Overexpression of PPARα ameliorated pathological hypertrophy and improved cardiac function. Augmented PPARα in hypertrophied myocytes revealed downregulated p53 acetylation (lys 382), leading to reduced apoptosis. Such cells showed increased binding of PPARα with p53 that in turn reduced interaction of p53 with glycogen synthase kinase-3β (GSK3β), which upregulated inactive phospho-GSK3β (serine [Ser]9) expression within mitochondrial protein fraction. Altogether, the altered molecular milieu in PPARα-overexpressed hypertrophy groups restored mitochondrial structure and function both in vitro and in vivo. Cardiomyocyte-targeted overexpression of a protein of interest (PPARα) by nanotized plasmid has been described for the first time in this study. Our data provide a novel insight towards regression of pathological hypertrophy by ameliorating mitochondrial oxidative stress in targeted PPARα-overexpressed myocardium. PPARα-overexpression during pathological hypertrophy showed substantial betterment of mitochondrial structure and function, along with downregulated apoptosis. Myocardium-targeted overexpression of PPARα during pathological cardiac hypertrophy led to an overall improvement of cardiac energy deficit and subsequent cardiac function, thereby, opening up a potential avenue for cardiac tissue engineering during hypertrophic cardiac pathophysiology.
Inability of p53-reactivating compounds Nutlin-3 and RITA to overcome p53 resistance in tumor cells deficient in p53Ser46 phosphorylation.

PubMed

Ma, Teng; Yamada, Shumpei; Ichwan, Solachuddin J A; Iseki, Sachiko; Ohtani, Kiyoshi; Otsu, Megumi; Ikeda, Masa-Aki

2012-01-20

The p53 tumor suppressor protein plays key roles in protecting cells from tumorigenesis. Phosphorylation of p53 at Ser46 (p53Ser46) is considered to be a crucial modification regulating p53-mediated apoptosis. Because the activity of p53 is impaired in most human cancers, restoration of wild-type p53 (wt-p53) function by its gene transfer or by p53-reactivating small molecules has been extensively investigated. The p53-reactivating compounds Nutlin-3 and RITA activate p53 in the absence of genotoxic stress by antagonizing the action of its negative regulator Mdm2. Although controversial, Nutlin-3 was shown to induce p53-mediated apoptosis in a manner independent of p53 phosphorylation. Recently, RITA was shown to induce apoptosis by promoting p53Ser46 phosphorylation. Here we examined whether Nutlin-3 or RITA can overcome resistance to p53-mediated apoptosis in p53-resistant tumor cell lines lacking the ability to phosphorylate p53Ser46. We show that Nutlin-3 did not rescue the apoptotic defect of a Ser46 phosphorylation-defective p53 mutant in p53-sensitive tumor cells, and that RITA neither restored p53Ser46 phosphorylation nor induced apoptosis in p53Ser46 phosphorylation-deficient cells retaining wt-p53. Furthermore, treatment with Nutlin-3 or RITA together with adenoviral p53 gene transfer also failed to induce apoptosis in p53Ser46 phosphorylation-deficient cells either expressing or lacking wt-p53. These results indicate that neither Nutlin-3 nor RITA in able to induce p53-mediated apoptosis in the absence of p53Ser46 phosphorylation. Thus, the dysregulation of this phosphorylation in tumor cells may be a critical factor that limits the efficacy of these p53-based cancer therapies. Copyright © 2011 Elsevier Inc. All rights reserved.
Regulation of hTERT Expression and Function in Newly Immortalized p53(+) Human Mammary Epithelial Cell Lines

DTIC Science & Technology

2008-06-01

proteins during embryogene- sis, neurodevelopment and cancer. Part of their function is through the repression of CKIs, including p16. Some functions...protein 2 Other AUTS2 autism susceptibility candidate 2 C1orf24 chromosome 1 open reading frame 24 C20orf97 chromosome 20 open reading frame 97
Regulation of hTERT Expression and Function in Newly Immortalized p53(+) Human Mammary Epithelial Cell Lines

DTIC Science & Technology

2007-06-01

embryogene- sis, neurodevelopment and cancer. Part of their function is through the repression of CKIs, including p16. Some functions have been attributed to...AUTS2 autism susceptibility candidate 2 C1orf24 chromosome 1 open reading frame 24 C20orf97 chromosome 20 open reading frame 97 DKFZP566B183
The human T-cell leukemia virus type-1 p30II protein activates p53 and induces the TIGAR and suppresses oncogene-induced oxidative stress during viral carcinogenesis.

PubMed

Romeo, Megan; Hutchison, Tetiana; Malu, Aditi; White, Averi; Kim, Janice; Gardner, Rachel; Smith, Katie; Nelson, Katherine; Bergeson, Rachel; McKee, Ryan; Harrod, Carolyn; Ratner, Lee; Lüscher, Bernhard; Martinez, Ernest; Harrod, Robert

2018-05-01

In normal cells, aberrant oncogene expression leads to the accumulation of cytotoxic metabolites, including reactive oxygen species (ROS), which can cause oxidative DNA-damage and apoptosis as an intrinsic barrier against neoplastic disease. The c-Myc oncoprotein is overexpressed in many lymphoid cancers due to c-myc gene amplification and/or 8q24 chromosomal translocations. Intriguingly, p53 is a downstream target of c-Myc and hematological malignancies, such as adult T-cell leukemia/lymphoma (ATL), frequently contain wildtype p53 and c-Myc overexpression. We therefore hypothesized that p53-regulated pro-survival signals may thwart the cell's metabolic anticancer defenses to support oncogene-activation in lymphoid cancers. Here we show that the Tp53-induced glycolysis and apoptosis regulator (TIGAR) promotes c-myc oncogene-activation by the human T-cell leukemia virus type-1 (HTLV-1) latency-maintenance factor p30 II , associated with c-Myc deregulation in ATL clinical isolates. TIGAR prevents the intracellular accumulation of c-Myc-induced ROS and inhibits oncogene-induced cellular senescence in ATL, acute lymphoblastic leukemia, and multiple myeloma cells with elevated c-Myc expression. Our results allude to a pivotal role for p53-regulated antioxidant signals as mediators of c-Myc oncogenic functions in viral and non-viral lymphoid tumors. Copyright © 2018 Elsevier Inc. All rights reserved.
Reduced hippocampal damage and epileptic seizures after status epilepticus in mice lacking proapoptotic Puma

PubMed Central

Engel, Tobias; Murphy, Brona M.; Hatazaki, Seiji; Jimenez-Mateos, Eva M.; Concannon, Caoimhin G.; Woods, Ina; Prehn, Jochen H. M.; Henshall, David C.

2010-01-01

The functional significance of neuronal death for pathogenesis of epilepsy and the underlying molecular mechanisms thereof remain incompletely understood. The p53 transcription factor has been implicated in seizure damage, but its target genes and the influence of cell death under its control on epilepsy development are unknown. In the present study, we report that status epilepticus (SE) triggered by intra-amygdala kainic acid in mice causes rapid p53 accumulation and subsequent hippocampal damage. Expression of p53-up-regulated mediator of apoptosis (Puma), a proapoptotic Bcl-2 homology domain 3-only protein under p53 control, was increased within a few hours of SE. Induction of Puma was blocked by pharmacologic inhibition of p53, and hippocampal damage was also reduced. Puma induction was also blocked in p53-deficient mice subject to SE. Compared to Puma-expressing mice, Puma-deficient mice had significantly smaller hippocampal lesions after SE. Long-term, continuous telemetric EEG monitoring revealed a ∼60% reduction in the frequency of epileptic seizures in the Puma-deficient mice compared to Puma-expressing mice. These are the first data showing genetic deletion of a proapoptotic protein acting acutely to influence neuronal death subsequently alters the phenotype of epilepsy in the long-term, supporting the concept that apoptotic pathway activation is a trigger of epileptogenesis.—Engel, T., Murphy, B. M., Hatazaki, S., Jimenez-Mateos, E. M., Concannon, C. G., Woods, I., Prehn, J. H. M., Henshall, D. C. Reduced hippocampal damage and epileptic seizures after status epilepticus in mice lacking proapoptotic Puma. PMID:19890018
Induction of tumor apoptosis through a circular RNA enhancing Foxo3 activity.

PubMed

Du, William W; Fang, Ling; Yang, Weining; Wu, Nan; Awan, Faryal Mehwish; Yang, Zhenguo; Yang, Burton B

2017-02-01

Circular RNAs are a class of non-coding RNAs that are receiving extensive attention. Despite reports showing circular RNAs acting as microRNA sponges, the biological functions of circular RNAs remain largely unknown. We show that in patient tumor samples and in a panel of cancer cells, circ-Foxo3 was minimally expressed. Interestingly, during cancer cell apoptosis, the expression of circ-Foxo3 was found to be significantly increased. We found that silencing endogenous circ-Foxo3 enhanced cell viability, whereas ectopic expression of circ-Foxo3 triggered stress-induced apoptosis and inhibited the growth of tumor xenografts. Also, expression of circ-Foxo3 increased Foxo3 protein levels but repressed p53 levels. By binding to both, circ-Foxo3 promoted MDM2-induced p53 ubiquitination and subsequent degradation, resulting in an overall decrease of p53. With low binding affinity to Foxo3 protein, circ-Foxo3 prevented MDM2 from inducing Foxo3 ubiquitination and degradation, resulting in increased levels of Foxo3 protein. As a result, cell apoptosis was induced by upregulation of the Foxo3 downstream target PUMA.
Expression profiles of SnoN in normal and cancerous human tissues support its tumor suppressor role in human cancer.

PubMed

Jahchan, Nadine S; Ouyang, Gaoliang; Luo, Kunxin

2013-01-01

SnoN is a negative regulator of TGF-β signaling and also an activator of the tumor suppressor p53 in response to cellular stress. Its role in human cancer is complex and controversial with both pro-oncogenic and anti-oncogenic activities reported. To clarify its role in human cancer and provide clinical relevance to its signaling activities, we examined SnoN expression in normal and cancerous human esophageal, ovarian, pancreatic and breast tissues. In normal tissues, SnoN is expressed in both the epithelium and the surrounding stroma at a moderate level and is predominantly cytoplasmic. SnoN levels in all tumor epithelia examined are lower than or similar to that in the matched normal samples, consistent with its anti-tumorigenic activity in epithelial cells. In contrast, SnoN expression in the stroma is highly upregulated in the infiltrating inflammatory cells in high-grade esophageal and ovarian tumor samples, suggesting that SnoN may potentially promote malignant progression through modulating the tumor microenvironment in these tumor types. The overall levels of SnoN expression in these cancer tissues do not correlate with the p53 status. However, in human cancer cell lines with amplification of the snoN gene, a strong correlation between increased SnoN copy number and inactivation of p53 was detected, suggesting that the tumor suppressor SnoN-p53 pathway must be inactivated, either through downregulation of SnoN or inactivation of p53, in order to allow cancer cell to proliferate and survive. These data strongly suggest that SnoN can function as a tumor suppressor at early stages of tumorigenesis in human cancer tissues.
Phosphorylation of p53 by LRRK2 induces microglial tumor necrosis factor α-mediated neurotoxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, Dong Hwan, E-mail: ethan2887@gmail.com; Seol, Wongi; Eun, Jin Hwan

Leucine-rich repeat kinase (LRRK2), a major causal gene of Parkinson's disease (PD), functions as a kinase. The most prevalent mutation of LRRK2 is G2019S. It exhibits increased kinase activity compared to the wildtype LRRK2. Previous studies have shown that LRRK2 can phosphorylate p53 at T304 and T377 of threonine-X-arginine (TXR) motif in neurons. Reduction of LRRK2 expression or inhibition of LRRK2 kinase activity has been shown to be able to alleviate LPS-induced neuroinflammation in microglia cells. In this study, we found that LRRK2 could also phosphorylate p53 in microglia model BV2 cells. Transfection of BV2 with phosphomimetic p53 T304/377D significantlymore » increased the secretion of pro-inflammatory cytokine TNFα compared to BV2 transfected with p53 wild type after LPS treatment. In addition, conditioned media from these transfected cells increased the death of dopaminergic neuronal SN4741 cells. Moreover, such neurotoxic effect was rescued by co-treatment with the conditioned media and etanercept, a TNFα blocking antibody. Furthermore, TNFα secretion was significantly increased in primary microglia derived from G2019S transgenic mice treated with LPS compared to that in cells derived from their littermates. These results suggest that LRRK2 kinase activity in microglia can contribute to neuroinflammation in PD via phosphorylating p53 at T304 and T377 site. - Highlights: • LPS stimulates LRRK2-mediated p53 phosphorylation and its nuclear localization. • Phosphorylation of p53 by LRRK2 in microglia enhances TNFα expression. • Microglial TNFα via LRRK2-induced p53 phosphorylation decreases neuronal survival.« less
P-Glycoprotein/MDR1 regulates pokemon gene transcription through p53 expression in human breast cancer cells.

PubMed

He, Shengnan; Liu, Feng; Xie, Zhenhua; Zu, Xuyu; Xu, Wei; Jiang, Yuyang

2010-08-27

P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy.
P-Glycoprotein/MDR1 Regulates Pokemon Gene Transcription Through p53 Expression in Human Breast Cancer Cells

PubMed Central

He, Shengnan; Liu, Feng; Xie, Zhenhua; Zu, Xuyu; Xu, Wei; Jiang, Yuyang

2010-01-01

P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy. PMID:20957096
Induction of Mitotic Cell Death by Overriding G2/M Checkpoint in Endometrial Cancer Cells with Non-functional p53

PubMed Central

Meng, Xiangbing; Laidler, Laura L.; Kosmacek, Elizabeth A.; Yang, Shujie; Xiong, Zhi; Zhu, Danlin; Wang, Xinjun; Dai, Donghai; Zhang, Yuping; Wang, Xiaofang; Brachova, Pavla; Albitar, Lina; Liu, Dawei; Ianzini, Fiorenza; Mackey, Michael A.; Leslie, Kimberly K.

2012-01-01

Objective Endometrial tumors with non-functional p53, such as serous uterine endometrial carcinomas, are aggressive malignancies with a poor outcome, yet they have an Achilles’ heel: due to loss of p53 function, these tumors may be sensitive to treatments which abrogate the G2/M checkpoint. Our objective was to exploit this weakness to induce mitotic cell death using two strategies: (1) EGFR inhibitor gefitinib combined with paclitaxel to arrest cells at mitosis, or (2) BI2536, an inhibitor of polo-like kinase 1 (PLK1), to block PLK1 activity. Methods We examined the impact of combining gefitinib and paclitaxel or PLK1 inhibitor on expression of G2/M checkpoint controllers, cell viability, and cell cycle progression in endometrial cancer cells with mutant p53. Results In cells lacking normal p53 activity, each treatment activated CDC25C and inactivated Wee1, which in turn activated cdc2 and sent cells rapidly through the G2/M checkpoint and into mitosis. Live cell imaging demonstrated irreversible mitotic arrest and eventual cell death. Combinatorial therapy with paclitaxel and gefitinib was highly synergistic and resulted in a 10-fold reduction in the IC50 for paclitaxel, from 14 nM as a single agent to 1.3 nM in the presence of gefitinib. However, BI2536 alone at low concentrations (5 nM) was the most effective treatment and resulted in massive mitotic cell death. In a xenograft mouse model with p53-deficient cells, low dose BI2536 significantly inhibited tumor growth. Conclusions These findings reveal induction of mitotic cell death as a therapeutic strategy for endometrial tumors lacking functional p53. PMID:23146687
Mitochondrial p53 mediates a transcription-independent regulation of cell respiration and interacts with the mitochondrial F₁F₀-ATP synthase

PubMed Central

Bergeaud, Marie; Mathieu, Lise; Guillaume, Arnaud; Moll, Ute M; Mignotte, Bernard; Le Floch, Nathalie; Vayssière, Jean-Luc; Rincheval, Vincent

2013-01-01

We and others previously reported that endogenous p53 can be located at mitochondria in the absence of stress, suggesting that p53 has a role in the normal physiology of this organelle. The aim of this study was to characterize in unstressed cells the intramitochondrial localization of p53 and identify new partners and functions of p53 in mitochondria. We find that the intramitochondrial pool of p53 is located in the intermembrane space and the matrix. Of note, unstressed HCT116 p53+/+ cells simultaneously show increased O₂ consumption and decreased mitochondrial superoxide production compared with their p53-null counterpart. This data was confirmed by stable H1299 cell lines expressing low levels of p53 specifically targeted to the matrix. Using immunoprecipitation and mass spectrometry, we identified the oligomycin sensitivity-conferring protein (OSCP), a subunit of the F₁F₀-ATP synthase complex, as a new partner of endogenous p53, specifically interacting with p53 localized in the matrix. Interestingly, this interaction seems implicated in mitochondrial p53 localization. Moreover, p53 localized in the matrix promotes the assembly of F₁F₀-ATP synthase. Taking into account that deregulations of mitochondrial respiration and reactive oxygen species production are tightly linked to cancer development, we suggest that mitochondrial p53 may be an important regulator of normal mitochondrial and cellular physiology, potentially exerting tumor suppression activity inside mitochondria. PMID:23966169
Mitochondrial p53 mediates a transcription-independent regulation of cell respiration and interacts with the mitochondrial F₁F0-ATP synthase.

PubMed

Bergeaud, Marie; Mathieu, Lise; Guillaume, Arnaud; Moll, Ute M; Mignotte, Bernard; Le Floch, Nathalie; Vayssière, Jean-Luc; Rincheval, Vincent

2013-09-01

We and others previously reported that endogenous p53 can be located at mitochondria in the absence of stress, suggesting that p53 has a role in the normal physiology of this organelle. The aim of this study was to characterize in unstressed cells the intramitochondrial localization of p53 and identify new partners and functions of p53 in mitochondria. We find that the intramitochondrial pool of p53 is located in the intermembrane space and the matrix. Of note, unstressed HCT116 p53(+/+) cells simultaneously show increased O₂ consumption and decreased mitochondrial superoxide production compared with their p53-null counterpart. This data was confirmed by stable H1299 cell lines expressing low levels of p53 specifically targeted to the matrix. Using immunoprecipitation and mass spectrometry, we identified the oligomycin sensitivity-conferring protein (OSCP), a subunit of the F₁F₀-ATP synthase complex, as a new partner of endogenous p53, specifically interacting with p53 localized in the matrix. Interestingly, this interaction seems implicated in mitochondrial p53 localization. Moreover, p53 localized in the matrix promotes the assembly of F₁F₀-ATP synthase. Taking into account that deregulations of mitochondrial respiration and reactive oxygen species production are tightly linked to cancer development, we suggest that mitochondrial p53 may be an important regulator of normal mitochondrial and cellular physiology, potentially exerting tumor suppression activity inside mitochondria.
MDM2 phenotypic and genotypic profiling, respective to TP53 genetic status, in diffuse large B-cell lymphoma patients treated with rituximab-CHOP immunochemotherapy: a report from the International DLBCL Rituximab-CHOP Consortium Program

PubMed Central

Xu-Monette, Zijun Y.; Møller, Michael B.; Tzankov, Alexander; Montes-Moreno, Santiago; Hu, Wenwei; Manyam, Ganiraju C.; Kristensen, Louise; Fan, Lei; Visco, Carlo; Dybkær, Karen; Chiu, April; Tam, Wayne; Zu, Youli; Bhagat, Govind; Richards, Kristy L.; Hsi, Eric D.; Choi, William W. L.; van Krieken, J. Han; Huang, Qin; Huh, Jooryung; Ai, Weiyun; Ponzoni, Maurilio; Ferreri, Andrés J. M.; Wu, Lin; Zhao, Xiaoying; Bueso-Ramos, Carlos E.; Wang, Sa A.; Go, Ronald S.; Li, Yong; Winter, Jane N.; Medeiros, L. Jeffrey

2013-01-01

MDM2 is a key negative regulator of the tumor suppressor p53, however, the prognostic significance of MDM2 overexpression in diffuse large B-cell lymphoma (DLBCL) has not been defined convincingly. In a p53 genetically–defined large cohort of de novo DLBCL patients treated with rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone (R-CHOP) chemotherapy, we assessed MDM2 and p53 expression by immunohistochemistry (n = 478), MDM2 gene amplification by fluorescence in situ hybridization (n = 364), and a single nucleotide polymorphism in the MDM2 promoter, SNP309, by SNP genotyping assay (n = 108). Our results show that MDM2 overexpression, unlike p53 overexpression, is not a significant prognostic factor in overall DLBCL. Both MDM2 and p53 overexpression do not predict for an adverse clinical outcome in patients with wild-type p53 but predicts for significantly poorer survival in patients with mutated p53. Variable p53 activities may ultimately determine the survival differences, as suggested by the gene expression profiling analysis. MDM2 amplification was observed in 3 of 364 (0.8%) patients with high MDM2 expression. The presence of SNP309 did not correlate with MDM2 expression and survival. This study indicates that evaluation of MDM2 and p53 expression correlating with TP53 genetic status is essential to assess their prognostic significance and is important for designing therapeutic strategies that target the MDM2-p53 interaction. PMID:23982177
Low p53 Binding Protein 1 (53BP1) Expression Is Associated With Increased Local Recurrence in Breast Cancer Patients Treated With Breast-Conserving Surgery and Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neboori, Hanmanth J.R.; Haffty, Bruce G., E-mail: hafftybg@umdnj.edu; Wu Hao

2012-08-01

Purpose: To investigate whether the expression of p53 binding protein 1 (53BP1) has prognostic significance in a cohort of early-stage breast cancer patients treated with breast-conserving surgery and radiotherapy (BCS+RT). Methods and Materials: A tissue microarray of early-stage breast cancer treated with BCS+RT from a cohort of 514 women was assayed for 53BP1, estrogen receptor, progesterone receptor, and HER2 expression by immunohistochemistry. Through log-rank tests and univariate and multivariate models, the staining profile of each tumor was correlated with clinical endpoints, including ipsilateral breast recurrence-free survival (IBRFS), distant metastasis-free survival (DMFS), cause-specific survival (CSS), recurrence-free survival (RFS), and overall survivalmore » (OS). Results: Of the 477 (93%) evaluable tumors, 63 (13%) were scored as low. Low expression of 53BP1 was associated with worse outcomes for all endpoints studied, including 10-year IBRFS (76.8% vs. 90.5%; P=.01), OS (66.4% vs. 81.7%; P=.02), CSS (66.0% vs. 87.4%; P<.01), DMFS (55.9% vs. 87.0%; P<.01), and RFS (45.2% vs. 80.6%; P<.01). Multivariate analysis incorporating various clinico-pathologic markers and 53BP1 expression found that 53BP1 expression was again an independent predictor of all endpoints (IBRFS: P=.0254; OS: P=.0094; CSS: P=.0033; DMFS: P=.0006; RFS: P=.0002). Low 53BP1 expression was also found to correlate with triple-negative (TN) phenotype (P<.01). Furthermore, in subset analysis of all TN breast cancer, negative 53BP1 expression trended for lower IBRFS (72.3% vs. 93.9%; P=.0361) and was significant for worse DMFS (48.2% vs. 86.8%; P=.0035) and RFS (37.8% vs. 83.7%; P=.0014). Conclusion: Our data indicate that low 53BP1 expression is an independent prognostic indicator for local relapse among other endpoints in early-stage breast cancer and TN breast cancer patients treated with BCS+RT. These results should be verified in larger cohorts of patients to validate their clinical significance.« less
RT-PCR amplification of RNA extracted from formalin-fixed, paraffin-embedded oral cancer sections: analysis of p53 pathway.

PubMed

Tachibana, Masatsugu; Shinagawa, Yasuhiro; Kawamata, Hitoshi; Omotehara, Fumie; Horiuchi, Hideki; Ohkura, Yasuo; Kubota, Keiichi; Imai, Yutaka; Fujibayashi, Takashi; Fujimori, Takahiro

2003-01-01

We present a new approach towards the detection of the mRNAs in formalin-fixed, paraffin-embedded samples using a reverse transcriptase (RT)-polymerase chain reaction (PCR). The total RNAs were extracted from 10-micron-thick sections and were reverse-transcribed, then the RT-products were subjected to PCR amplification of GAPDH mRNA for screening the mRNA degradation. Next, nested PCR was performed for examining the expression of p53-related genes, p21WAF1, MDM2, p33ING1 and p14ARF. GAPDH mRNA expression was detectable in 12 out of 21 oral squamous cell carcinoma (SCC) samples. p21WAF1 mRNA expression was detectable in 5 out of 12 SCC samples, MDM2 mRNA expression was detectable in 5 our of 12 SCC samples and p33ING1 mRNA expression was detectable in 6 out of 12 SCC samples. However, the expression of p14ARF mRNA was not detectable in any of the samples. Seven out of 12 oral SCC samples showed abnormal nuclear accumulation of p53 protein by immunohistochemical staining, whereas 5 out of 12 oral SCCs showed negative staining for p53 protein. Of of p33ING1 mRNA. One of these was a verrucous carcinoma in which the p53 gene products might be inactivated by the oncoprotein E6 of human papilloma virus. Thus, the p53 tumor suppressor pathway was disrupted in most oral SCCs at the cellular levels, due to either an abnormality in p53 itself or loss of expression of p53 regulatory factors. This method would assist in making diagnosis, determining therapeutic strategy and predicting the prognosis of various cancers including oral SCCs.
ΔNp63 promotes pediatric neuroblastoma and osteosarcoma by regulating tumor angiogenesis

PubMed Central

Bid, Hemant K.; Roberts, Ryan D.; Cam, Maren; Audino, Anthony; Kurmasheva, Raushan T.; Lin, Jiayuh; Houghton, Peter J.; Cam, Hakan

2013-01-01

The tumor suppressor gene p53 and its family members p63/p73 are critical determinants of tumorigenesis. ΔNp63 is a splice variant of p63, which lacks the N-terminal transactivation domain. It is thought to antagonize p53-, p63- and p73- dependent translation, thus blocking their tumor suppressor activity. In our studies of the pediatric solid tumors neuroblastoma and osteosarcoma, we find overexpression of ΔNp63; however, there is no correlation of ΔNp63 expression with p53 mutation status. Our data suggest that ΔNp63 itself endows cells with a gain of function that leads to malignant transformation, a function independent of any p53 antagonism. Here, we demonstrate that ΔNp63 overexpression, independent of p53, increases secretion of interleukin-6 (IL-6) and interleukin-8 (IL-8), leading to elevated phosphorylation of STAT-3 (Tyr-705). We show that elevated phosphorylation of STAT-3 leads to stabilization of HIF-1α protein, resulting in VEGF secretion. We also show human clinical data, which suggests a mechanistic role for ΔNp63 in osteosarcoma metastasis. In summary, our studies reveal the mechanism by which ΔNp63, as a master transcription factor, modulates tumor angiogenesis. PMID:24154873
BCAS2 promotes prostate cancer cells proliferation by enhancing AR mRNA transcription and protein stability

PubMed Central

Kuo, P-C; Huang, C-W; Lee, C-I; Chang, H-W; Hsieh, S-W; Chung, Y-P; Lee, M-S; Huang, C-S; Tsao, L-P; Tsao, Y-P; Chen, S-L

2015-01-01

Background: We showed previously that breast carcinoma amplified sequence 2 (BCAS2) functions as a negative regulator of p53. We also found that BCAS2 is a potential AR-associated protein. AR is essential for the growth and survival of prostate carcinoma. Therefore we characterised the correlation between BCAS2 and AR. Methods: Protein interactions were examined by GST pull-down assay and co-immunoprecipitation. Clinical prostate cancer (PCa) specimens were evaluated by immunohistochemical assay. AR transcriptional activity and LNCaP cell growth were assessed by luciferase assay and MTT assay, respectively. Results: BCAS2 expression was significantly increased in PCa. BCAS2 stabilised AR protein through both hormone-dependent and -independent manners. There are at least two mechanisms for BCAS2-mediated AR protein upregulation: One is p53-dependent. The p53 is suppressed by BCAS2 that results in increasing AR mRNA and protein expression. The other is via p53-independent inhibition of proteasome degradation. As BCAS2 can form a complex with AR and HSP90, it may function with HSP90 to stabilise AR protein from being degraded by proteasome. Conclusions: In this study, we show that BCAS2 is a novel AR-interacting protein and characterise the correlation between BCAS2 and PCa. Thus we propose that BCAS2 could be a diagnostic marker and therapeutic target for PCa. PMID:25461807

SIRT1 activation by resveratrol reduces brain edema and neuronal apoptosis in an experimental rat subarachnoid hemorrhage model.

PubMed

Qian, Cong; Jin, Jianxiang; Chen, Jingyin; Li, Jianru; Yu, Xiaobo; Mo, Hangbo; Chen, Gao

2017-12-01

Early brain injury is considered to be a major risk that is related to the prognosis of subarachnoid hemorrhage (SAH). In SAH model rats, brain edema and apoptosis have been closely related with death rate and neurological function. Sirtuin 1 (SIRT1) was reported to be involved in apoptosis in cerebral ischemia and brain tumor formation through p53 deacetylation. The present study aimed to evaluate the role of SIRT1 in a rat endovascular perforation model of SAH. The SIRT1 activator resveratrol (RES) was administered 48 h prior to SAH induction and the SIRT1 inhibitor Sirtinol (SIR) was used to reverse the effects of RES on SIRT1 expression. Mortality rate, neurological function and brain water content were measured 24 h post‑SAH induction. Proteins associated with the blood brain barrier (BBB), apoptosis and SIRT1 in the cortex, such as zona occludens 1 (ZO‑1), occludin, claudin‑5, SIRT1, p53 and cleaved caspase3 were investigated. mRNA expression of the p53 downstream molecules including Bcl‑associated X protein, P53 upregulated modulator of apoptosis, Noxa and BH3 interacting‑domain death agonist were also investigated. Neuronal apoptosis was also investigated by immunofluorescence. RES pretreatment reduced the mortality rate and improved neurological function, which was consistent with reduced brain water content and neuronal apoptosis; these effects were partially reversed by co‑treatment with SIR. SIRT1 may reduce the brain water content by improvement of dysfunctional BBB permeability, and protein analysis revealed that both ZO‑1, occludin and claudin‑5 may be involved, and these effects were reversed by SIRT1 inhibition. SIRT1 may also affect apoptosis post‑SAH through p53 deacetylation, and the analysis of p53 related downstream pro‑apoptotic molecules supported this hypothesis. Localization of neuron specific apoptosis revealed that SIRT1 may regulate neuronal apoptosis following SAH. SIRT1 may also ease brain edema and neuronal protection through BBB improvement and p53 deacetylation. SIRT1 activators such as RES may have the potential to improve the prognosis of patients with SAH and clinical research should be investigated further.
Altered S-nitrosylation of p53 is responsible for impaired antioxidant response in skeletal muscle during aging.

PubMed

Baldelli, Sara; Ciriolo, Maria Rosa

2016-12-20

p53 transcriptional activity has been proposed to regulate both homeostasis and sarcopenia of skeletal muscle during aging. However, the exact molecular function of p53 remains to be clearly defined. We demonstrated a requirement of nuclear p53 S-nitrosylation in inducing a nitric oxide/PGC-1α-mediated antioxidant pathway in skeletal muscle. Importantly, mutant form of p53-DNA binding domain (C124S) did not undergo nuclear S-nitrosylation and failed in inducing the expression of antioxidant genes (i.e. SOD2 and GCLC). Moreover, we found that during aging the nuclear S-nitrosylation of p53 significantly declines in gastrocnemius/soleus leading to an impairment of redox homeostasis of skeletal muscle. We suggested that decreased level of nuclear neuronal nitric oxide synthase (nNOS)/Syntrophin complex, which we observed during aging, could be responsible for impaired nuclear S-nitrosylation. Taken together, our data indicate that altered S-nitrosylation of p53 during aging could be a contributing factor of sarcopenia condition and of other skeletal muscle pathologies associated with oxidative/nitrosative stress.
Altered S-nitrosylation of p53 is responsible for impaired antioxidant response in skeletal muscle during aging

PubMed Central

Baldelli, Sara; Ciriolo, Maria Rosa

2016-01-01

p53 transcriptional activity has been proposed to regulate both homeostasis and sarcopenia of skeletal muscle during aging. However, the exact molecular function of p53 remains to be clearly defined. We demonstrated a requirement of nuclear p53 S-nitrosylation in inducing a nitric oxide/PGC-1α-mediated antioxidant pathway in skeletal muscle. Importantly, mutant form of p53-DNA binding domain (C124S) did not undergo nuclear S-nitrosylation and failed in inducing the expression of antioxidant genes (i.e. SOD2 and GCLC). Moreover, we found that during aging the nuclear S-nitrosylation of p53 significantly declines in gastrocnemius/soleus leading to an impairment of redox homeostasis of skeletal muscle. We suggested that decreased level of nuclear neuronal nitric oxide synthase (nNOS)/Syntrophin complex, which we observed during aging, could be responsible for impaired nuclear S-nitrosylation. Taken together, our data indicate that altered S-nitrosylation of p53 during aging could be a contributing factor of sarcopenia condition and of other skeletal muscle pathologies associated with oxidative/nitrosative stress. PMID:28025407
The up-regulation of miR-300 in gastric cancer and its effects on cells malignancy

PubMed Central

Shen, Zhen; Li, Chunsheng; Zhang, Kai; Yu, Wei; Xiao, Huijie; Li, Bo; Liu, Tongjun

2015-01-01

Objective: In this study, we investigated the role of miR-300 in regulating cell proliferation and invasion of gastric cancer cells. Methods: MicroRNA and protein expression patterns were compared between gastric cancer tissue and normal tissue and between two different prognostic groups. The up-regulation of miR-300 was confirmed by real-time reverse transcription polymerase chain reaction and its expression was analyzed in AGS gastric cancer cells. Results: We observed that miR-300 expression was frequently and dramatically up-regulated in human gastric cancer tissues and cell lines compared with the matched adjacent normal tissues and cells. We further showed that transient and stable over-expression of miR-300 could promote cell proliferation and cell cycle progression. Moreover, p53, a key inhibitor of cell cycle, was verified as a direct target of miR-300, suggesting that miR-300 might promote gastric cancer cell proliferation and invasion by increasing p53 expression. Conclusion: Our findings indicated that miR-300 up-regulation might exert some sort of antagonistic function by targeting p53 in gastric cancer cell proliferation during gastric tumorigenesis. PMID:26221215
The up-regulation of miR-300 in gastric cancer and its effects on cells malignancy.

PubMed

Shen, Zhen; Li, Chunsheng; Zhang, Kai; Yu, Wei; Xiao, Huijie; Li, Bo; Liu, Tongjun

2015-01-01

In this study, we investigated the role of miR-300 in regulating cell proliferation and invasion of gastric cancer cells. MicroRNA and protein expression patterns were compared between gastric cancer tissue and normal tissue and between two different prognostic groups. The up-regulation of miR-300 was confirmed by real-time reverse transcription polymerase chain reaction and its expression was analyzed in AGS gastric cancer cells. We observed that miR-300 expression was frequently and dramatically up-regulated in human gastric cancer tissues and cell lines compared with the matched adjacent normal tissues and cells. We further showed that transient and stable over-expression of miR-300 could promote cell proliferation and cell cycle progression. Moreover, p53, a key inhibitor of cell cycle, was verified as a direct target of miR-300, suggesting that miR-300 might promote gastric cancer cell proliferation and invasion by increasing p53 expression. Our findings indicated that miR-300 up-regulation might exert some sort of antagonistic function by targeting p53 in gastric cancer cell proliferation during gastric tumorigenesis.
Correlation between cell cycle proteins and hMSH2 in actinic cheilitis and lip cancer.

PubMed

Lopes, Maria Luiza Diniz de Sousa; de Oliveira, Denise Hélen Imaculada Pereira; Sarmento, Dmitry José de Santana; Queiroz, Lélia Maria Guedes; Miguel, Márcia Cristina da Costa; da Silveira, Éricka Janine Dantas

2016-04-01

This study aims to evaluate and verify the relationship between the immunoexpression of hMSH2, p53 and p21 in actinic cheilitis (AC) and lower lip squamous cell carcinoma (SCC) cases. Forty AC and 40 SCC cases were submitted to immunoperoxidase method and quantitatively analyzed. Expression was compared by Mann-Whitney test, Student t test or one-way ANOVA. To correlate the variables, Pearson's correlation coefficient was calculated. The expression of p53 and p21 showed no significant differences between histopathological grades of AC or lower lip SCC (p > 0.05). Immunoexpression of p53 was higher in SCC than in AC (p < 0.001), while p21 expression was more observed in AC when compared to SCC group (p = 0.006). The AC group revealed an inverse correlation between p53 and hMSH2 expression (r = -0.30, p = 0.006). Alterations in p53 and p21 expression suggest that these proteins are involved in lower lip carcinogenesis. Moreover, p53 and hMSH2 seem to be interrelated in early events of this process.
CTCF regulates the human p53 gene through direct interaction with its natural antisense transcript, Wrap53

PubMed Central

Saldaña-Meyer, Ricardo; González-Buendía, Edgar; Guerrero, Georgina; Narendra, Varun; Bonasio, Roberto; Recillas-Targa, Félix; Reinberg, Danny

2014-01-01

The multifunctional CCCTC-binding factor (CTCF) protein exhibits a broad range of functions, including that of insulator and higher-order chromatin organizer. We found that CTCF comprises a previously unrecognized region that is necessary and sufficient to bind RNA (RNA-binding region [RBR]) and is distinct from its DNA-binding domain. Depletion of cellular CTCF led to a decrease in not only levels of p53 mRNA, as expected, but also those of Wrap53 RNA, an antisense transcript originated from the p53 locus. PAR-CLIP-seq (photoactivatable ribonucleoside-enhanced cross-linking and immunoprecipitation [PAR-CLIP] combined with deep sequencing) analyses indicate that CTCF binds a multitude of transcripts genome-wide as well as to Wrap53 RNA. Apart from its established role at the p53 promoter, CTCF regulates p53 expression through its physical interaction with Wrap53 RNA. Cells harboring a CTCF mutant in its RBR exhibit a defective p53 response to DNA damage. Moreover, the RBR facilitates CTCF multimerization in an RNA-dependent manner, which may bear directly on its role in establishing higher-order chromatin structures in vivo. PMID:24696455
Suppression of Familial Adenomatous Polyposis by CP-31398, a TP53 modulator, in APCmin/+ Mice1

PubMed Central

Rao, Chinthalapally V.; Swamy, Malisetty V.; Patlolla, Jagan M.R.; Kopelovich, Levy

2008-01-01

p53 mutations occur in a large number of human malignancies. Mutant p53 is unable to affect downstream genes necessary for DNA repair, cell cycle regulation, and apoptosis. The styrylquinazoline CP-31398 can rescue destabilized mutant p53 expression and promote activity of wild-type p53. The present study examines chemopreventive effects of CP-31398 on intestinal adenoma development in an animal model of familial adenomatous polyposis (FAP). Effects were examined at both early and late stages of adenoma formation. Effects of CP-31398 on early-stage adenomas were determined by feeding 7-week-old female C57B/6J-APCmin (heterozygous) and wild-type C57BL/6J mice with American Institute of Nutrition (AIN)-76A diets containing 0, 100, or 200 ppm CP-31398 for 75 days. To examine activity toward late-stage adenomas, CP31398 administration was delayed until 15 weeks of age and continued for 50 days. During early-stage intervention, dietary CP-31398 suppressed development of intestinal tumors by 36% (p < 0.001) and 75% (p < 0.0001), at low and high dose, respectively. During late-stage intervention, CP-31398 also significantly suppressed intestinal polyp formation, albeit to a lesser extent than observed with early intervention. Adenomas in treated mice showed increased apoptotic cell death and decreased proliferation in conjunction with increased expression of p53, p21WAF1/CIP, cleaved caspase-3, and cleaved poly (ADP-ribose) polymerase (PARP). These observations demonstrate for the first time that the p53-modulating agent CP-31398 possesses significant chemopreventive activity in vivo against intestinal neoplastic lesions in genetically-predisposed APCmin/+ mice. Chemopreventive activity of other agents that restore tumor suppressor functions of mutant p53 in tumor cells is currently under investigation. PMID:18794156
Vitamin D receptor deficit induces activation of renin angiotensin system via SIRT1 modulation in podocytes.

PubMed

Chandel, Nirupama; Ayasolla, Kamesh; Wen, Hongxiu; Lan, Xiqian; Haque, Shabirul; Saleem, Moin A; Malhotra, Ashwani; Singhal, Pravin C

2017-02-01

Vitamin D receptor (VDR) deficient status has been shown to be associated with the activation of renin angiotensin system (RAS). We hypothesized that lack of VDR would enhance p53 expression in podocytes through down regulation of SIRT1; the former would enhance the transcription of angiotensinogen (Agt) and angiotensinogen II type 1 receptor (AT1R) leading to the activation of RAS. Renal tissues of VDR mutant (M) mice displayed increased expression of p53, Agt, renin, and AT1R. In vitro studies, VDR knockout podocytes not only displayed up regulation p53 but also displayed enhanced expression of Agt, renin and AT1R. VDR deficient podocytes also displayed an increase in mRNA expression for p53, Agt, renin, and AT1R. Interestingly, renal tissues of VDR-M as well as VDR heterozygous (h) mice displayed attenuated expression of deacetylase SIRT1. Renal tissues of VDR-M mice showed acetylation of p53 at lysine (K) 382 residues inferring that enhanced p53 expression in renal tissues could be the result of ongoing acetylation, a consequence of SIRT1 deficient state. Notably, podocytes lacking SIRT1 not only showed acetylation of p53 at lysine (K) 382 residues but also displayed enhanced p53 expression. Either silencing of SIRT1/VDR or treatment with high glucose enhanced podocyte PPAR-y expression, whereas, immunoprecipitation (IP) of their lysates with anti-retinoid X receptor (RXR) antibody revealed presence of PPAR-y. It appears that either the deficit of SIRT1 has de-repressed expression of PPAR-y or enhanced podocyte expression of PPAR-y (in the absence of VDR) has contributed to the down regulation of SIRT1. Copyright © 2017 Elsevier Inc. All rights reserved.
BAG3 down-modulation sensitizes HPV18(+) HeLa cells to PEITC-induced apoptosis and restores p53.

PubMed

Cotugno, Roberta; Basile, Anna; Romano, Elena; Gallotta, Dario; Belisario, Maria Antonietta

2014-11-28

BAG3 is a multi-functional component of tumor cell pro-survival machinery, and its biological functions have been largely associated to proteasome system. Here, we show that BAG3 down-modulation resulted in reduced cell viability and enhanced PEITC-induced apoptosis largely more extensively in HeLa (HPV18(+)) rather than in C33A (HPV(-)) cervical carcinoma cell lines. Moreover, we demonstrate that BAG3 suppression led to a decrease of viral E6 oncoprotein and a concomitant recovery of p53 tumor suppressor, the best recognized target of E6 for proteasome degradation. E6 and p53 expression were modulated at protein level, since their respective mRNAs were unaffected. Taken together our findings reveal a novel role for BAG3 as host protein contributing to HPV18 E6-activated pro-survival strategies, and suggest a possible relevance of its expression levels in drug/radiotherapy-resistance of HPV18-bearing cervical carcinomas. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Immunohistochemistry Study of P53 and C-erbB-2 Expression in Trophoblastic Tissue and Their Predictive Values in Diagnosing Malignant Progression of Simple Molar Pregnancy

PubMed Central

Hasanzadeh, Malihe; Sharifi, Norrie; Farazestanian, Marjaneh; Nazemian, Seyed Saman; Madani Sani, Faezeh

2016-01-01

Background Finding a tumor marker to predict the aggressive behavior of molar pregnancy in early stages has yet been a topic for studies. Objectives In this survey we planned to study patients with molar pregnancy to 1) assess the p53 and c-erbB-2 expression in trophoblastic tissue, 2) to study the relationship between their expression intensity and progression of a molar pregnancy to gestational trophoblastic neoplasia, and 3) to determine a cut off value for the amount of p53 and c-erbB-2 expression which might correlate with aggressive behavior of molar pregnancy. Patients and Methods In a prospective cross sectional study by using a high accuracy technique EnVision Tm system for immunohistochemistry staining of molar pregnancy samples, we evaluated p53 and c-erbB-2 expression in cytotrophoblast and syncytiotrophoblast and the correlation of their expression with progression of molar pregnancy to gestational trophoblastic neoplasia (GTN). Normal prostatic tissue and Breast cancer tissue were used as positive controls. Results We studied 28 patients with simple molar pregnancy (SMP) and 30 with GTN. Cytotrophobalst had significantly higher expression of p53 and c-erbB-2 and syncytiotrophoblast had greater expression of p53 in GTN group as compared to SMP group. The cut off values for percentage of p53 positive immunostained cytotrophoblast and syncytiotrophoblast were 5.5% and 2.5%. In c-erbB-2 positive membranous stained cytotrophoblast the cut off was 12.5%. Conclusions Our data suggests that over expression of p53 and c-erbB-2 is associated with malignant progression of molar pregnancy. We encountered that high expression of p53 and c-erbB-2 in trophoblastic cells could predict gestational trophoblastic neoplasia during the early stages. PMID:27703642
Molecular Regulation of DNA Damage-Induced Apoptosis in Neurons of Cerebral Cortex

PubMed Central

Liu, Zhiping; Pipino, Jacqueline; Chestnut, Barry; Landek, Melissa A.

2009-01-01

Cerebral cortical neuron degeneration occurs in brain disorders manifesting throughout life, but the mechanisms are understood poorly. We used cultured embryonic mouse cortical neurons and an in vivo mouse model to study mechanisms of DNA damaged-induced apoptosis in immature and differentiated neurons. p53 drives apoptosis of immature and differentiated cortical neurons through its rapid and prominent activation stimulated by DNA strand breaks induced by topoisomerase-I and -II inhibition. Blocking p53-DNA transactivation with α-pifithrin protects immature neurons; blocking p53-mitochondrial functions with μ-pifithrin protects differentiated neurons. Mitochondrial death proteins are upregulated in apoptotic immature and differentiated neurons and have nonredundant proapoptotic functions; Bak is more dominant than Bax in differentiated neurons. p53 phosphorylation is mediated by ataxia telangiectasia mutated (ATM) kinase. ATM inactivation is antiapoptotic, particularly in differentiated neurons, whereas inhibition of c-Abl protects immature neurons but not differentiated neurons. Cell death protein expression patterns in mouse forebrain are mostly similar to cultured neurons. DNA damage induces prominent p53 activation and apoptosis in cerebral cortex in vivo. Thus, DNA strand breaks in cortical neurons induce rapid p53-mediated apoptosis through actions of upstream ATM and c-Abl kinases and downstream mitochondrial death proteins. This molecular network operates through variations depending on neuron maturity. PMID:18820287
Histogram analysis of ADC in rectal cancer: associations with different histopathological findings including expression of EGFR, Hif1-alpha, VEGF, p53, PD1, and KI 67. A preliminary study.

PubMed

Meyer, Hans Jonas; Höhn, Annekathrin; Surov, Alexey

2018-04-06

Functional imaging modalities like Diffusion-weighted imaging are increasingly used to predict tumor behavior like cellularity and vascularity in different tumors. Histogram analysis is an emergent imaging analysis, in which every voxel is used to obtain a histogram and therefore statistically information about tumors can be provided. The purpose of this study was to elucidate possible associations between ADC histogram parameters and several immunhistochemical features in rectal cancer. Overall, 11 patients with histologically proven rectal cancer were included into the study. There were 2 (18.18%) females and 9 males with a mean age of 67.1 years. KI 67-index, expression of p53, EGFR, VEGF, and Hif1-alpha were semiautomatically estimated. The tumors were divided into PD1-positive and PD1-negative lesions. ADC histogram analysis was performed as a whole lesion measurement using an in-house matlab application. Spearman's correlation analysis revealed a strong correlation between EGFR expression and ADCmax (p=0.72, P=0.02). None of the vascular parameters (VEGF, Hif1-alpha) correlated with ADC parameters. Kurtosis and skewness correlated inversely with p53 expression (p=-0.64, P=0.03 and p=-0.81, P=0.002, respectively). ADCmedian and ADCmode correlated with Ki67 (p=-0.62, P=0.04 and p=-0.65, P=0.03, respectively). PD1-positive tumors showed statistically significant lower ADCmax values in comparison to PD1-negative tumors, 1.93 ± 0.36 vs 2.32 ± 0.47×10 -3 mm 2 /s, p=0.04. Several associations were identified between histogram parameter derived from ADC maps and EGFR, KI 67 and p53 expression in rectal cancer. Furthermore, ADCmax was different between PD1 positive and PD1 negative tumors indicating an important role of ADC parameters for possible future treatment prediction.
Histogram analysis of ADC in rectal cancer: associations with different histopathological findings including expression of EGFR, Hif1-alpha, VEGF, p53, PD1, and KI 67. A preliminary study

PubMed Central

Meyer, Hans Jonas; Höhn, Annekathrin; Surov, Alexey

2018-01-01

Functional imaging modalities like Diffusion-weighted imaging are increasingly used to predict tumor behavior like cellularity and vascularity in different tumors. Histogram analysis is an emergent imaging analysis, in which every voxel is used to obtain a histogram and therefore statistically information about tumors can be provided. The purpose of this study was to elucidate possible associations between ADC histogram parameters and several immunhistochemical features in rectal cancer. Overall, 11 patients with histologically proven rectal cancer were included into the study. There were 2 (18.18%) females and 9 males with a mean age of 67.1 years. KI 67-index, expression of p53, EGFR, VEGF, and Hif1-alpha were semiautomatically estimated. The tumors were divided into PD1-positive and PD1-negative lesions. ADC histogram analysis was performed as a whole lesion measurement using an in-house matlab application. Spearman's correlation analysis revealed a strong correlation between EGFR expression and ADCmax (p=0.72, P=0.02). None of the vascular parameters (VEGF, Hif1-alpha) correlated with ADC parameters. Kurtosis and skewness correlated inversely with p53 expression (p=-0.64, P=0.03 and p=-0.81, P=0.002, respectively). ADCmedian and ADCmode correlated with Ki67 (p=-0.62, P=0.04 and p=-0.65, P=0.03, respectively). PD1-positive tumors showed statistically significant lower ADCmax values in comparison to PD1-negative tumors, 1.93 ± 0.36 vs 2.32 ± 0.47×10−3mm2/s, p=0.04. Several associations were identified between histogram parameter derived from ADC maps and EGFR, KI 67 and p53 expression in rectal cancer. Furthermore, ADCmax was different between PD1 positive and PD1 negative tumors indicating an important role of ADC parameters for possible future treatment prediction. PMID:29719621
Protective role of p53 in skin cancer: Carcinogenesis studies in mice lacking epidermal p53.

PubMed

Page, Angustias; Navarro, Manuel; Suarez-Cabrera, Cristian; Alameda, Josefa P; Casanova, M Llanos; Paramio, Jesús M; Bravo, Ana; Ramirez, Angel

2016-04-12

p53 is a protein that causes cell cycle arrest, apoptosis or senescence, being crucial in the process of tumor suppression in several cell types. Different in vitro and animal models have been designed for the study of p53 role in skin cancer. These models have revealed opposing results, as in some experimental settings it appears that p53 protects against skin cancer, but in others, the opposite conclusion emerges. We have generated cohorts of mice with efficient p53 deletion restricted to stratified epithelia and control littermates expressing wild type p53 and studied their sensitivity to both chemically-induced and spontaneous tumoral transformation, as well as the tumor types originated in each experimental group. Our results indicate that the absence of p53 in stratified epithelia leads to the appearance, in two-stage skin carcinogenesis experiments, of a higher number of tumors that grow faster and become malignant more frequently than tumors arisen in mice with wild type p53 genotype. In addition, the histological diversity of the tumor type is greater in mice with epidermal p53 loss, indicating the tumor suppressive role of p53 in different epidermal cell types. Aging mice with p53 inactivation in stratified epithelia developed spontaneous carcinomas in skin and other epithelia. Overall, these results highlight the truly protective nature of p53 functions in the development of cancer in skin and in other stratified epithelia.
Unbalancing p53/Mdm2/IGF-1R axis by Mdm2 activation restrains the IGF-1-dependent invasive phenotype of skin melanoma

PubMed Central

Worrall, C; Suleymanova, N; Crudden, C; Trocoli Drakensjö, I; Candrea, E; Nedelcu, D; Takahashi, S-I; Girnita, L; Girnita, A

2017-01-01

Melanoma tumors usually retain wild-type p53; however, its tumor-suppressor activity is functionally disabled, most commonly through an inactivating interaction with mouse double-minute 2 homolog (Mdm2), indicating p53 release from this complex as a potential therapeutic approach. P53 and the tumor-promoter insulin-like growth factor type 1 receptor (IGF-1R) compete as substrates for the E3 ubiquitin ligase Mdm2, making their relative abundance intricately linked. Hence we investigated the effects of pharmacological Mdm2 release from the Mdm2/p53 complex on the expression and function of the IGF-1R. Nutlin-3 treatment increased IGF-1R/Mdm2 association with enhanced IGF-1R ubiquitination and a dual functional outcome: receptor downregulation and selective downstream signaling activation confined to the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway. This Nutlin-3 functional selectivity translated into IGF-1-mediated bioactivities with biphasic effects on the proliferative and metastatic phenotype: an early increase and late decrease in the number of proliferative and migratory cells, while the invasiveness was completely inhibited following Nutlin-3 treatment through an impaired IGF-1-mediated matrix metalloproteinases type 2 activation mechanism. Taken together, these experiments reveal the biased agonistic properties of Nutlin-3 for the mitogen-activated protein kinase pathway, mediated by Mdm2 through IGF-1R ubiquitination and provide fundamental insights into destabilizing p53/Mdm2/IGF-1R circuitry that could be developed for therapeutic gain. PMID:28092675
Combined radiation and p53 gene therapy of malignant glioma cells.

PubMed

Badie, B; Goh, C S; Klaver, J; Herweijer, H; Boothman, D A

1999-01-01

More than half of malignant gliomas reportedly have alterations in the p53 tumor suppressor gene. Because p53 plays a key role in the cellular response to DNA-damaging agents, we investigated the role of p53 gene therapy before ionizing radiation in cultured human glioma cells containing normal or mutated p53. Three established human glioma cell lines expressing the wild-type (U87 MG, p53wt) or mutant (A172 and U373 MG, p53mut) p53 gene were transduced by recombinant adenoviral vectors bearing human p53 (Adp53) and Escherichia coli beta-galactosidase genes (AdLacZ, control virus) before radiation (0-20 Gy). Changes in p53, p21, and Bax expression were studied by Western immunoblotting, whereas cell cycle alterations and apoptosis were investigated by flow cytometry and nuclear staining. Survival was assessed by clonogenic assays. Within 48 hours of Adp53 exposure, all three cell lines demonstrated p53 expression at a viral multiplicity of infection of 100. p21, which is a p53-inducible downstream effector gene, was overexpressed, and cells were arrested in the G1 phase. Bax expression, which is thought to play a role in p53-induced apoptosis, did not change with either radiation or Adp53. Apoptosis and survival after p53 gene therapy varied. U87 MG (p53wt) cells showed minimal apoptosis after Adp53, irradiation, or combined treatments. U373 MG (p53mut) cells underwent massive apoptosis and died within 48 hours of Adp53 treatment, independent of irradiation. Surprisingly, A172 (p53mut) cells demonstrated minimal apoptosis after Adp53 exposure; however, unlike U373 MG cells, apoptosis increased with radiation dose. Survival of all three cell lines was reduced dramatically after >10 Gy. Although Adp53 transduction significantly reduced the survival of U373 MG cells and inhibited A172 growth, it had no effect on the U87 MG cell line. Transduction with AdLacZ did not affect apoptosis or cell cycle progression and only minimally affected survival in all cell lines. We conclude that responses to p53 gene therapy are variable among gliomas and most likely depend upon both cellular p53 status and as yet ill-defined downstream pathways involving activation of cell cycle regulatory and apoptotic genes.
Antibody to human α-fetoprotein inhibits cell growth of human hepatocellular carcinoma cells by resuscitating the PTEN molecule: in vitro experiments.

PubMed

Ohkawa, Kiyoshi; Asakura, Tadashi; Tsukada, Yutaka; Matsuura, Tomokazu

2017-06-01

It has been proposed that α-fetoprotein (AFP) is a new member of the intracellular signaling molecule family of the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway via interaction with the phosphatase and tensin homolog (PTEN). In this study, the effects of anti-human AFP antibody on the functions of PTEN were examined using an AFP-producing human hepatoma cell line. The antibody caused significant inhibition of cell growth, compared to a normal IgG control, with the accumulation of intracellular immune complexes followed by significant reduction of cytosolic functional AFP. Decrease in the amount of AKT phosphorylated on serine (S) 473 indicated that PI3K/AKT signaling was suppressed in the cells. S380-phosphorylated PTEN increased markedly by the second day after antibody treatment, with slight but significant increase in the PTEN protein level. Since phosphorylation at S380 is critical for PTEN stability, the increase in S380-phosphorylated PTEN indicated maintenance of the number of PTEN molecules and the related potential to control PI3K/AKT signaling. p53 protein (P53) significantly, but slightly increased during antibody treatment, because PTEN expression increased the stability and function of P53 via both molecular interactions. P53 phosphorylated at S20 or at S392 dramatically increased, suggesting an increase in the stability, accumulation and activation of P53. Glucose transporter 1 (GLUT1) increased immediately after antibody treatment, pointing to a deficiency of glucose in the cells. Immunofluorescence cytology revealed that antibody-treatment re-distributed GLUT1 molecules throughout the cytoplasm with a reduction of their patchy localization on the cell surface. This suggested that translocation of GLUT1 depends on the PI3K/AKT pathway, in particular on PTEN expression. Antibody therapy targeted at AFP-producing tumor cells showed an inhibitory effect on the PI3K/AKT pathway via the liberation, restoration and functional stabilization of PTEN. PTEN simultaneously induced both P53 activation and intracellular translocation of GLUT1, since these are closely associated with PTEN.
p21WAF1 immunohistochemical expression in breast carcinoma: correlations with clinicopathological data, oestrogen receptor status, MIB1 expression, p53 gene and protein alterations and relapse-free survival.

PubMed Central

Barbareschi, M.; Caffo, O.; Doglioni, C.; Fina, P.; Marchetti, A.; Buttitta, F.; Leek, R.; Morelli, L.; Leonardi, E.; Bevilacqua, G.; Dalla Palma, P.; Harris, A. L.

1996-01-01

p21 protein (p21) inhibitor of cyclin-dependent kinases is a critical downstream effector in the p53-specific pathway of growth control. p21 can also be induced by p53-independent pathways in relation to terminal differentiation. We investigated p21 immunoreactivity in normal breast and in 91 breast carcinomas [three in situ ductal carcinomas (DCIS) with microinfiltration and 88 infiltrating carcinomas, 17 of which with an associated DCIS; 57 node negative and 34 node positive] with long-term follow-up (median = 58 months). Seven additional breast carcinomas with known p53 gene mutations were investigated. In normal breast p21 expression was seen in the nuclei of rare luminal cells of acinar structures, and in occasional myoepithelial cells. Poorly differentiated DCIS showed high p21 expression, whereas well-differentiated DCIS tumours showed few p21-reactive cells. p21 was seen in 82 (90%) infiltrating tumours; staining was heterogeneous; the percentage of reactive nuclei ranged from 1% to 35%. High p21 expression (more than 10% of reactive cells) was seen in 24 (26%) cases, and was associated with high tumour grade (P = 0.032); no associations were seen with tumour size, metastases, oestrogen receptor status, MIB1 expression and p53 expression. p21 expression in cases with p53 gene mutations was low in six cases and high in one. High p21 expression was associated with short relapse-free survival (P = 0.003). Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:8688323
Age-Related Susceptibility to Apoptosis in Human Retinal Pigment Epithelial Cells Is Triggered by Disruption of p53–Mdm2 Association

PubMed Central

Bhattacharya, Sujoy; Chaum, Edward; Johnson, Dianna A.; Johnson, Leonard R.

2012-01-01

Purpose. Relatively little is known about the contribution of p53/Mdm2 pathway in apoptosis of retinal pigment epithelial (RPE) cells or its possible link to dysfunction of aging RPE or to related blinding disorders such as age-related macular degeneration (AMD). Methods. Age-associated changes in p53 activation were evaluated in primary RPE cultures from human donor eyes of various ages. Apoptosis was evaluated by activation of caspases and DNA fragmentation. Gene-specific small interfering RNA was used to knock down expression of p53. Results. We observed that the basal rate of p53-dependent apoptosis increased in an age-dependent manner in human RPE. The age-dependent increase in apoptosis was linked to alterations in several aspects of the p53 pathway. p53 phosphorylation Ser15 was increased through the stimulation of ATM-Ser1981. p53 acetylation Lys379 was increased through the inhibition of SIRT1/2. These two posttranslational modifications of p53 blocked the sequestration of p53 by Mdm2, thus resulting in an increase in free p53 and of p53 stimulation of apoptosis through increased expression of PUMA (p53 upregulated modulator of apoptosis) and activation of caspase-3. Aged RPE also had reduced expression of antiapoptotic Bcl-2, which contributed to the increase in apoptosis. Of particular interest in these studies was that pharmacologic treatments to block p53 phosphorylation, acetylation, or expression were able to protect RPE cells from apoptosis. Conclusions. Our studies suggest that aging in the RPE leads to alterations of specific checkpoints in the apoptotic pathway, which may represent important molecular targets for the treatment of RPE-related aging disorders such as AMD. PMID:23139272

Regulatory RNA Key Player in p53-Mediated Apoptosis in Embryonic Stem Cells | Center for Cancer Research

Cancer.gov

Embryonic stem cells (ESCs) must maintain the integrity of their genomes or risk passing potentially deleterious mutations on to numerous tissues. Thus, ESCs have a unique genome surveillance system and easily undergo apoptosis or differentiation when DNA damage is detected. The protein p53 is known to promote differentiation in mouse ESCs (mESCs), but its role in DNA damage-induced apoptosis (DIA) is unclear. p53 may have a pro-apoptotic function since it can regulate apoptotic genes in embryonal cells. Given that ESCs have a distinct transcriptional program, Jing Huang, Ph.D., of CCR’s Laboratory of Cancer Biology and Genetics, and his colleagues wondered whether p53 might regulate DIA in ESCs by utilizing the ESC-specific expression program.
Optimized p53 immunohistochemistry is an accurate predictor of TP53 mutation in ovarian carcinoma.

PubMed

Köbel, Martin; Piskorz, Anna M; Lee, Sandra; Lui, Shuhong; LePage, Cecile; Marass, Francesco; Rosenfeld, Nitzan; Mes Masson, Anne-Marie; Brenton, James D

2016-10-01

TP53 mutations are ubiquitous in high-grade serous ovarian carcinomas (HGSOC), and the presence of TP53 mutation discriminates between high and low-grade serous carcinomas and is now an important biomarker for clinical trials targeting mutant p53. p53 immunohistochemistry (IHC) is widely used as a surrogate for TP53 mutation but its accuracy has not been established. The objective of this study was to test whether improved methods for p53 IHC could reliably predict TP53 mutations independently identified by next generation sequencing (NGS). Four clinical p53 IHC assays and tagged-amplicon NGS for TP53 were performed on 171 HGSOC and 80 endometrioid carcinomas (EC). p53 expression was scored as overexpression (OE), complete absence (CA), cytoplasmic (CY) or wild type (WT). p53 IHC was evaluated as a binary classifier where any abnormal staining predicted deleterious TP53 mutation and as a ternary classifier where OE, CA or WT staining predicted gain-of-function (GOF or nonsynonymous), loss-of-function (LOF including stopgain, indel, splicing) or no detectable TP53 mutations (NDM), respectively. Deleterious TP53 mutations were detected in 169/171 (99%) HGSOC and 7/80 (8.8%) EC. The overall accuracy for the best performing IHC assay for binary and ternary prediction was 0.94 and 0.91 respectively, which improved to 0.97 (sensitivity 0.96, specificity 1.00) and 0.95 after secondary analysis of discordant cases. The sensitivity for predicting LOF mutations was lower at 0.76 because p53 IHC detected mutant p53 protein in 13 HGSOC with LOF mutations. CY staining associated with LOF was seen in 4 (2.3%) of HGSOC. Optimized p53 IHC can approach 100% specificity for the presence of TP53 mutation and its high negative predictive value is clinically useful as it can exclude the possibility of a low-grade serous tumour. 4.1% of HGSOC cases have detectable WT staining while harboring a TP53 LOF mutation, which limits sensitivity for binary prediction of mutation to 96%.
Optimized p53 immunohistochemistry is an accurate predictor of TP53 mutation in ovarian carcinoma

PubMed Central

Köbel, Martin; Piskorz, Anna M; Lee, Sandra; Lui, Shuhong; LePage, Cecile; Marass, Francesco; Rosenfeld, Nitzan; Mes Masson, Anne‐Marie

2016-01-01

Abstract TP53 mutations are ubiquitous in high‐grade serous ovarian carcinomas (HGSOC), and the presence of TP53 mutation discriminates between high and low‐grade serous carcinomas and is now an important biomarker for clinical trials targeting mutant p53. p53 immunohistochemistry (IHC) is widely used as a surrogate for TP53 mutation but its accuracy has not been established. The objective of this study was to test whether improved methods for p53 IHC could reliably predict TP53 mutations independently identified by next generation sequencing (NGS). Four clinical p53 IHC assays and tagged‐amplicon NGS for TP53 were performed on 171 HGSOC and 80 endometrioid carcinomas (EC). p53 expression was scored as overexpression (OE), complete absence (CA), cytoplasmic (CY) or wild type (WT). p53 IHC was evaluated as a binary classifier where any abnormal staining predicted deleterious TP53 mutation and as a ternary classifier where OE, CA or WT staining predicted gain‐of‐function (GOF or nonsynonymous), loss‐of‐function (LOF including stopgain, indel, splicing) or no detectable TP53 mutations (NDM), respectively. Deleterious TP53 mutations were detected in 169/171 (99%) HGSOC and 7/80 (8.8%) EC. The overall accuracy for the best performing IHC assay for binary and ternary prediction was 0.94 and 0.91 respectively, which improved to 0.97 (sensitivity 0.96, specificity 1.00) and 0.95 after secondary analysis of discordant cases. The sensitivity for predicting LOF mutations was lower at 0.76 because p53 IHC detected mutant p53 protein in 13 HGSOC with LOF mutations. CY staining associated with LOF was seen in 4 (2.3%) of HGSOC. Optimized p53 IHC can approach 100% specificity for the presence of TP53 mutation and its high negative predictive value is clinically useful as it can exclude the possibility of a low‐grade serous tumour. 4.1% of HGSOC cases have detectable WT staining while harboring a TP53 LOF mutation, which limits sensitivity for binary prediction of mutation to 96%. PMID:27840695
Oncogenic functions of tumour suppressor p21(Waf1/Cip1/Sdi1): association with cell senescence and tumour-promoting activities of stromal fibroblasts.

PubMed

Roninson, Igor B

2002-05-08

p21(Waf1/Cip1/Sdi1) is best known as a broad-specificity inhibitor of cyclin/cyclin-dependent kinase complexes, but p21 also interacts with many other regulators of transcription or signal transduction. p21 induction, which is mediated by p53 and by p53-independent mechanisms, is essential for the onset of cell cycle arrest in damage response and cell senescence. The effects of p21 knockout in mice and its expression patterns in human cancer are consistent with a role for p21 as both a tumour suppressor and an oncogene. Several functions of p21 are likely to promote carcinogenesis and tumour progression. These include endoreduplication and abnormal mitosis that develop in tumour cells after release from p21-induced growth arrest, the ability of p21 to inhibit apoptosis through several different mechanisms, and its ability to stimulate transcription of secreted factors with mitogenic and anti-apoptotic activities. The latter effects of p21 show close resemblance to paracrine activities of senescent cells and to tumour-promoting functions of stromal fibroblasts. Therapeutic strategies targeting the oncogenic consequences of p21 expression may provide a new approach to chemoprevention and treatment of cancer.
Transactivation domain of p53 regulates DNA repair and integrity in human iPS cells.

PubMed

Kannappan, Ramaswamy; Mattapally, Saidulu; Wagle, Pooja A; Zhang, Jianyi

2018-05-18

The role of p53 transactivation domain (p53-TAD), a multifunctional and dynamic domain, on DNA repair and retaining DNA integrity in human iPS cells has never been studied. p53-TAD was knocked out in iPS cells using CRISPR/Cas9 and was confirmed by DNA sequencing. p53-TAD KO cells were characterized by: accelerated proliferation, decreased population doubling time, and unaltered Bcl2, BBC3, IGF1R, Bax and altered Mdm2, p21, and PIDD transcripts expression. In p53-TAD KO cells p53 regulated DNA repair proteins XPA, DNA polH and DDB2 expression were found to be reduced compared to p53-WT cells. Exposure to low dose of doxorubicin (Doxo) induced similar DNA damage and DNA damage response (DDR) measured by RAD50 and MRE11 expression, Checkpoint kinase 2 activation and γH2A.X recruitment at DNA strand breaks in both the cell groups indicating silencing p53-TAD do not affect DDR mechanism upstream of p53. Following removal of Doxo p53-WT hiPS cells underwent DNA repair, corrected their damaged DNA and restored DNA integrity. Conversely, p53-TAD KO hiPS cells did not undergo complete DNA repair and failed to restore DNA integrity. More importantly continuous culture of p53-TAD KO hiPS cells underwent G2/M cell cycle arrest and expressed cellular senescent marker p16 INK4a . Our data clearly shows that silencing transactivation domain of p53 did not affect DDR but affected the DNA repair process implying the crucial role of p53 transactivation domain in maintaining DNA integrity. Therefore, activating p53-TAD domain using small molecules may promote DNA repair and integrity of cells and prevent senescence.
Loss of p53-inducible long non-coding RNA LINC01021 increases chemosensitivity

PubMed Central

Kaller, Markus; Götz, Ursula; Hermeking, Heiko

2017-01-01

We have previously identified the long non-coding RNA LINC01021 as a direct p53 target (Hünten et al. Mol Cell Proteomics. 2015; 14:2609-2629). Here, we show that LINC01021 is up-regulated in colorectal cancer (CRC) cell lines upon various p53-activating treatments. The LINC01021 promoter and the p53 binding site lie within a MER61C LTR, which originated from insertion of endogenous retrovirus 1 (ERV1) sequences. Deletion of this MER61C element by a CRISPR/Cas9 approach, as well as siRNA-mediated knockdown of LINC01021 RNA significantly enhanced the sensitivity of the CRC cell line HCT116 towards the chemotherapeutic drugs doxorubicin and 5-FU, suggesting that LINC01021 is an integral part of the p53-mediated response to DNA damage. Inactivation of LINC01021 and also its ectopic expression did not affect p53 protein expression and transcriptional activity, implying that LINC01021 does not feedback to p53. Furthermore, in CRC patient samples LINC01021 expression positively correlated with a wild-type p53-associated gene expression signature. LINC01021 expression was increased in primary colorectal tumors and displayed a bimodal distribution that was particularly pronounced in the mesenchymal CMS4 consensus molecular subtype of CRCs. CMS4 tumors with low LINC01021 expression were associated with poor patient survival. Our results suggest that the genomic redistribution of ERV1-derived p53 response elements and generation of novel p53-inducible lncRNA-encoding genes was selected for during primate evolution as integral part of the cellular response to various forms of genotoxic stress. PMID:29262524
Immunohistochemical expression of protein p53 in neoplasms of the mammary gland in bitches.

PubMed

Rodo, A; Malicka, E

2008-01-01

The aim of the study was to investigate the presence of protein p53 in correlation with other tumor traits: histological type, tumor grade and proliferative activity. Material for the investigation comprised mammary gland tumours collected from dogs, the patients of veterinary clinics, during surgical procedures, and archival samples. Alltogether 21 adenomas, 31 complex carcinomas, 35 simple carcinomas and 12 solid carcinomas were qualified for further investigation. No protein p53 expression was found in adenomas. Cancers show positive reaction in 32.5%. The highest percent of p53 positive neoplasms was observed in solid carcinomas and neoplasms with the highest degree of histological malignancy. The smallest number showing this expression was observed in adenomas and the highest was characteristic for solid carcinomas. Considering the tumour grading, it was found that an increase in neoplasm malignancy was positively correlated with the number of the cells showing the expression of protein p53. The differences were statistically significant. Statistically significant positive correlations were observed between the proliferative activity and protein p53 expression. Higher accumulation of protein p53 in more malignant neoplasms suggests that mutations of protein p53 can be responsible for higher proliferation in neoplasms with advanced progression of malignancy.
Celecoxib enhances the radiosensitivity of HCT116 cells in a COX-2 independent manner by up-regulating BCCIP

PubMed Central

Xu, Xiao-Ting; Hu, Wen-Tao; Zhou, Ju-Ying; Tu, Yu

2017-01-01

It has been reported that celecoxib, a cyclooxygenase-2 (COX-2)-selective nonsteroidal anti-inflammatory drug (NSAID), regulates the radiosensitivity of several cancer cells. BCCIP (BRCA2 and CDKN1A interacting protein) plays a critical role in maintaining the critical functions of p53 in tumor suppression and response to therapy. However, whether the effect of celecoxib on the radiosensitivity of colorectal cancer (CRC) cells is dependent on BCCIP is largely unclear. In this study, we found that celecoxib enhanced the radiosensitivity of HeLa (a human cervical carcinoma cell line), A549 (a human lung carcinoma cell line), and HCT116 cells (a human CRC cells line). Among these cells, COX-2 expression was undetected in HCT116 cells. Treatment with celecoxib significantly increased BCCIP expression in COX-2 negative HCT116 cells. Knockdown of BCCIP obviously abrogated the enhanced radiosensitivity of HCT116 cells induced by celecoxib. A combination of celecoxib and irradiation treatment induced much more γ-H2AX foci formation, higher levels of radiation injury-related proteins phosphorylation, G2/M arrest, apoptosis, and p53 and p21 expression, and lower levels of Cyclin B1 in HCT116 cells than those in cells treated with irradiation alone. However, these changes were undetected in BCCIP-silenced HCT116 cells. Therefore, these data suggest that BCCIP gene may be a radiosensitivity-related gene in CRC. Celecoxib affects the functions of p53 and inhibits the recovery from the irradiation-induced injury by up-regulating the expression of BCCIP, and subsequently regulates the expressions of genes such as p21 and Cyclin B1 to enhance the radiosensitivity of HCT116 cells in a COX-2 independent manner. PMID:28386336
Downregulated long non-coding RNA MEG3 in breast cancer regulates proliferation, migration and invasion by depending on p53’s transcriptional activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Lin; Li, Yu; Yang, Bangxiang, E-mail: b19933009@qq.coom

Long non-coding RNAs (lncRNAs) was found to play critical roles in tumorigenesis, hence, screen of tumor-related lncRNAs, identification of their biological roles is important for understanding the processes of tumorigenesis. In this study, we identified the expressing difference of several tumor-related lncRNAs in breast cancer samples and found that, MEG3, which is downregulated in non-small cell lung cancer (NSCLC) tumor tissues, is also downregulated in breast cancer samples compared with adjacent tissues. For figuring out the effect of MEG3 in breast cancer cells MCF7 and MB231, we overexpressed MEG3 in these cells, and found that it resulted the inhibition ofmore » proliferation, colony formation, migration and invasion capacities by enhancing p53’s transcriptional activity on its target genes, including p21, Maspin and KAI1. MEG3 presented similar effects in MB157, which is a p53-null breast cancer cell line, when functional p53 but not p53R273H mutant, which lacks transcriptional activity, was introduced. Surprisingly, overexpression of MEG3 activates p53’s transcriptional activity by decreasing MDM2’s transcription level, and thus stabilizes and accumulates P53. Taken together, our findings indicate that MEG3 is downregulated in breast cancer tissues and affects breast cancer cells’ malignant behaviors, which indicate MEG3 a potential therapeutic target for breast cancer. - Highlights: • MEG3 RNA is widely downregulated in breast tumor tissue. • MEG3 regulates P53 indirectly through transcriptional regulation of MDM2. • Under unstressed condition, MEG3-related P53 accumulation transcriptionally activates p53’s target genes. • MEG3 expression level tightly regulates proliferation, colony formation, migration and invasion in breast tumor cells.« less
Preeclampsia Is Associated with Alterations in the p53-Pathway in Villous Trophoblast

PubMed Central

Sharp, Andrew N.; Heazell, Alexander E. P.; Baczyk, Dora; Dunk, Caroline E.; Lacey, Helen A.; Jones, Carolyn J. P.; Perkins, Jonathan E.; Kingdom, John C. P.; Baker, Philip N.; Crocker, Ian P.

2014-01-01

Background Preeclampsia (PE) is characterized by exaggerated apoptosis of the villous trophoblast of placental villi. Since p53 is a critical regulator of apoptosis we hypothesized that excessive apoptosis in PE is mediated by abnormal expression of proteins participating in the p53 pathway and that modulation of the p53 pathway alters trophoblast apoptosis in vitro. Methods Fresh placental villous tissue was collected from normal pregnancies and pregnancies complicated by PE; Western blotting and real-time PCR were performed on tissue lysate for protein and mRNA expression of p53 and downstream effector proteins, p21, Bax and caspases 3 and 8. To further assess the ability of p53 to modulate apoptosis within trophoblast, BeWo cells and placental villous tissue were exposed to the p53-activator, Nutlin-3, alone or in combination with the p53-inhibitor, Pifithrin-α (PFT- α). Equally, Mdm2 was knocked-down with siRNA. Results Protein expression of p53, p21 and Bax was significantly increased in pregnancies complicated by PE. Conversely, Mdm2 protein levels were significantly depleted in PE; immunohistochemistry showed these changes to be confined to trophoblast. Reduction in the negative feedback of p53 by Mdm2, using siRNA and Nutlin-3, caused an imbalance between p53 and Mdm2 that triggered apoptosis in term villous explants. In the case of Nutlin, this was attenuated by Pifithrin-α. Conclusions These data illustrate the potential for an imbalance in p53 and Mdm2 expression to promote excessive apoptosis in villous trophoblast. The upstream regulation of p53 and Mdm2, with regard to exaggerated apoptosis and autophagy in PE, merits further investigation. PMID:24498154
Preeclampsia is associated with alterations in the p53-pathway in villous trophoblast.

PubMed

Sharp, Andrew N; Heazell, Alexander E P; Baczyk, Dora; Dunk, Caroline E; Lacey, Helen A; Jones, Carolyn J P; Perkins, Jonathan E; Kingdom, John C P; Baker, Philip N; Crocker, Ian P

2014-01-01

Preeclampsia (PE) is characterized by exaggerated apoptosis of the villous trophoblast of placental villi. Since p53 is a critical regulator of apoptosis we hypothesized that excessive apoptosis in PE is mediated by abnormal expression of proteins participating in the p53 pathway and that modulation of the p53 pathway alters trophoblast apoptosis in vitro. Fresh placental villous tissue was collected from normal pregnancies and pregnancies complicated by PE; Western blotting and real-time PCR were performed on tissue lysate for protein and mRNA expression of p53 and downstream effector proteins, p21, Bax and caspases 3 and 8. To further assess the ability of p53 to modulate apoptosis within trophoblast, BeWo cells and placental villous tissue were exposed to the p53-activator, Nutlin-3, alone or in combination with the p53-inhibitor, Pifithrin-α (PFT-α). Equally, Mdm2 was knocked-down with siRNA. Protein expression of p53, p21 and Bax was significantly increased in pregnancies complicated by PE. Conversely, Mdm2 protein levels were significantly depleted in PE; immunohistochemistry showed these changes to be confined to trophoblast. Reduction in the negative feedback of p53 by Mdm2, using siRNA and Nutlin-3, caused an imbalance between p53 and Mdm2 that triggered apoptosis in term villous explants. In the case of Nutlin, this was attenuated by Pifithrin-α. These data illustrate the potential for an imbalance in p53 and Mdm2 expression to promote excessive apoptosis in villous trophoblast. The upstream regulation of p53 and Mdm2, with regard to exaggerated apoptosis and autophagy in PE, merits further investigation.
Thymidilate synthase and p53 primary tumour expression as predictive factors for advanced colorectal cancer patients

PubMed Central

Paradiso, A; Simone, G; Petroni, S; Leone, B; Vallejo, C; Lacava, J; Romero, A; Machiavelli, M; Lena, M De; Allegra, C J; Johnston, P G

2000-01-01

The purpose of this work was to analyse the ability of p53 and thymidilate synthase (TS) primary tumour expression to retrospectively predict clinical response to chemotherapy and long-term prognosis in patients with advanced colorectal cancers homogeneously treated by methotrexate (MTX)-modulated–5-fluorouracil (5-FU-FA). A total of 108 advanced colorectal cancer patients entered the present retrospective study. Immunohistochemical p53 (pAb 1801 mAb) and TS (TS106 mAb) expression on formalin-fixed paraffin-embedded primary tumour specimens was related to probability of clinical response to chemotherapy, time to progression and overall survival. p53 was expressed in 53/108 (49%) tumours, while 54/108 (50%) showed TS immunostaining. No relationship was demonstrated between p53 positivity and clinical response to chemotherapy (objective response (OR): 20% vs 23%, in p53+ and p53– cases respectively) or overall survival. Percent of OR was significantly higher in TS-negative with respect to TS-positive tumours (30% vs 15% respectively;P< 0.04); simultaneous analysis of TS and p53 indicated 7% OR for p53-positive/TS-positive tumours vs 46% for p53-positive/TS-negative tumours (P< 0.03). Logistic regression analysis confirmed a significant association between TS tumour status and clinical response to chemotherapy (hazard ratio (HR): 2.91; 95% confidence interval (CI) 8.34–1.01; two-sided P< 0.05). A multivariate analysis of overall survival showed that only a small number of metastatic sites was statistically relevant (HR 1.89; 95% CI 2.85–1.26; two-sided P< 0.03). Our study suggests that immunohistochemical expression of p53 and TS could assist the clinician in predicting response of colorectal cancer patients to modulated MTX-5-FU therapy. © 2000 Cancer Research Campaign PMID:10682666
Immunohistochemical co-expression status of cytokeratin 5/6, androgen receptor, and p53 as prognostic factors of adjuvant chemotherapy for triple negative breast cancer.

PubMed

Maeda, Tetsuyo; Nakanishi, Yoko; Hirotani, Yukari; Fuchinoue, Fumi; Enomoto, Katsuhisa; Sakurai, Kenichi; Amano, Sadao; Nemoto, Norimichi

2016-03-01

Triple negative breast cancer (TNBC) is immunohistochemically characterised by the lack of expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor type 2 (HER2). TNBC is known for its poor prognosis and high recurrence probability. There is no effective targeted treatment for TNBC, but only adjuvant chemotherapies. There are two TNBC subtypes, basal-like and non-basal-like, which are defined based on positive cytokeratin (CK) 5/6 and/or epidermal growth factor receptor (EGFR) expression. In particular, CK5/6 expression is reported to correlate with TNBC recurrence. TNBC lacks ER-α expression, but some TNBCs are known to express the androgen receptor (AR). Moreover, although p53 accumulation is detected in various malignant tumors, its influence on adjuvant chemotherapy for patients with TNBC remains unclear. The aim of this study was to assess the combined immunohistochemical expression of CK 5/6, AR, and p53 as a potential prognostic marker of adjuvant chemotherapy for patients with TNBC. The expression of CK5/6, AR, and p53 in formalin-fixed and paraffin-embedded (FFPE) surgical sections from 52 patients with TNBC was analysed by immunohistochemistry (IHC) and the co-expression patterns in individual cells were investigated by immunofluorescent (IF) staining. Low AR expression was correlated with high clinical stage (P < 0.05) and low nuclear grade (P < 0.05). The expression of CK5/6 and p53 did not correlate with clinicopathological features. Patients who needed adjuvant chemotherapy presented the worst prognosis. In particular, when the IHC expression pattern was CK5/6 (-), AR (-), and p53 (+), the disease free survival (DFS) and overall survival (OS) were the worst. On the other hand, patients with AR (+) and p53 (-) TNBC presented a good prognosis. The analysis of the co-expression status of these three markers showed that no cells presented both AR and CK5/6 expression. Furthermore, TP53 mRNA expression was higher in patients with AR-negative TNBC (P < 0.05) and in patients with the worst prognosis (P < 0.05) than in the other patients. These results suggested that, in patients with CK5/6-negative TNBC, AR expression correlated with good prognosis, but p53 accumulation correlated with poor prognosis. The present IHC markers allowed us to predict the post-surgery prognosis of patients with TNBC. In conclusion, TNBCs are heterogeneous. Patients with the CK5/6 (-), AR (-), and p53 (+) TNBC subtype, evaluated by IHC, presented the worst prognosis. These IHC markers will be helpful to follow patients with TNBC.
LACTB, a novel epigenetic silenced tumor suppressor, inhibits colorectal cancer progression by attenuating MDM2-mediated p53 ubiquitination and degradation.

PubMed

Zeng, Kaixuan; Chen, Xiaoxiang; Hu, Xiuxiu; Liu, Xiangxiang; Xu, Tao; Sun, Huiling; Pan, Yuqin; He, Bangshun; Wang, Shukui

2018-06-13

Colorectal cancer (CRC) is one of the most common aggressive malignancies. Like other solid tumors, inactivation of tumor suppressor genes and activation of oncogenes occur during CRC development and progression. Recently, a novel tumor suppressor, LACTB, was proposed to inhibit tumor progression, but the functional and clinical significance of this tumor suppressor in CRC remains unexplored. Herein, we found LACTB was significantly downregulated in CRC due to promoter methylation and histone deacetylation, which was associated with metastasis and advanced clinical stage. CRC patients with low LACTB expression had poorer overall survival and LACTB also determined to be an independent prognostic factor for poorer outcome. Ectopic expression of LACTB suppressed CRC cells proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro and inhibited CRC growth and metastasis in vivo, while knockout of LACTB by CRISPR/Cas9 gene editing technique resulted in an opposite phenotype. Interestingly, LACTB could exert antitumorigenic effect only in HCT116 and HCT8 cells harboring wild-type TP53, but not in HT29 and SW480 cells harboring mutant TP53 or HCT116 p53 -/- cells. Mechanistic studies demonstrated that LACTB could directly bind to the C terminus of p53 to inhibit p53 degradation by preventing MDM2 from interacting with p53. Moreover, ablation of p53 attenuated the antitumorigenic effects of LACTB overexpression in CRC. Collectively, our findings successfully demonstrate for the first time that LACTB is a novel epigenetic silenced tumor suppressor through modulating the stability of p53, supporting the pursuit of LACTB as a potential therapeutic target for CRC.
Nutlin-3 induces HO-1 expression by activating JNK in a transcription-independent manner of p53.

PubMed

Choe, Yun-Jeong; Lee, Sun-Young; Ko, Kyung Won; Shin, Seok Joon; Kim, Ho-Shik

2014-03-01

A recent study reported that p53 can induce HO-1 by directly binding to the putative p53 responsive element in the HO-1 promoter. In this study, we report that nutlin-3, a small molecule antagonist of HDM2, induces the transcription of HO-1 in a transcription-independent manner of p53. Nutlin-3 induced HO-1 expression at the level of transcription in human cancer cells such as U2OS and RKO cells. This induction of HO-1 did not occur in SAOS cells in which p53 was mutated and was prevented by knocking down the p53 protein using p53 siRNA transfection, but not by PFT-α, an inhibitor of the transcriptional activity of p53. Accompanying HO-1 expression, nutlin-3 stimulated the accumulation of ROS and the phosphorylation of MAPKs such as JNK, p38 MAPK and ERK1/2. Nutlin-3-induced HO-1 expression was suppressed by TEMPO, a ROS scavenger, and chemical inhibitors of JNK and p38 MAPK but not ERK1/2. In addition, nutlin‑3-induced phosphorylation of JNK but not p38 MAPK was inhibited by TEMPO. Notably, the levels of nutlin-3-induced ROS were correlated with the mitochondrial translocation of p53 and this induction was prevented by PFT-μ, an inhibitor of the mitochondrial translocation of p53. Consistent with the effect of the ROS scavenger and MAPK inhibitors, PFT-μ reduced HO-1 expression and the phosphorylation of JNK induced by nutlin-3. In the experiments of analyzing cell death, the knockdown of HO-1 augmented nutlin-3-induced apoptosis. Collectively, these results suggest that nutlin-3 induces HO-1 expression via the activation of both JNK which is dependent on ROS generated by p53 translocated to the mitochondria and p38 MAPK which appears to be stimulated by a ROS-independent mechanism, and this HO-1 induction may inhibit nutlin-3-induced apoptosis, constituting a negative feedback loop of p53-induced apoptosis.
Mutant p53 expression in kidney tubules adjacent to renal cell carcinoma: evidence of a precursor lesion.

PubMed

Lai, R; el Dabbagh, L; Mourad, W A

1996-06-01

Neoplastic transformation can be associated with mutations of the p53 gene. This leads to stabilization of its protein product and to its accumulation, which allows immunohistochemical detection. Mutant p53 expression has been seen in many neoplasms, including renal cell carcinoma (RCC). We recently described putative precursor lesions of RCC. The lesions were defined as intratubular epithelial dysplasia (IED) of kidney tubules adjacent to RCC. They were seen in one-third of the cases studied. The findings were based only on light microscopic analysis. We hypothesized that neoplastic transformation would be manifested by mutant p53 expression in the kidney tubules adjacent to RCC and not in nonneoplastic kidneys. Immunohistochemical staining for p53 in 24 cases of RCC with adjacent kidneys was performed. We used the DO-7 monoclonal antibody reactive for the N-terminal of the p53 protein on formalin-fixed paraffin-embedded tissue. Sections from 14 kidneys resected for nonneoplastic conditions were used as controls. Twenty-one (87%) of the 24 cases of RCC had nuclear p53 expression in the tumor cells. This included 14 cases (58%) with intense reactivity and 7 cases (29%) with weaker p53 immunoreactivity. Of the 24 cases of RCC, IED was identified in 13 cases (54%). Immunoreactivity for p53 was focally seen in tubules of all the lesions, as well as in the nonlesional areas. Six of the lesions exhibited intense nuclear staining. The kidneys adjacent to the RCC, with no evidence of IED, showed focally intense positive p53 nuclear staining in four cases. None of the control specimens showed p53 expression. Our findings provide supportive evidence that previously described IED in kidneys adjacent to RCC are most likely precursor lesions of the neoplasm. Aberrant expression of p53 in areas without evidence of IED may suggest that neoplastic transformation manifested by p53 mutation in kidney tubules may be seen before the development of the morphologic features of dysplasia and malignancy.
The effect of Zhangfei/CREBZF on cell growth, differentiation, apoptosis, migration, and the unfolded protein response in several canine osteosarcoma cell lines.

PubMed

Zhang, Rui; Thamm, Douglas H; Misra, Vikram

2015-02-07

We had previously shown that the bLZip domain-containing transcription factor, Zhangfei/CREBZF inhibits the growth and the unfolded protein response (UPR) in cells of the D-17 canine osteosarcoma (OS) line and that the effects of Zhangfei are mediated by it stabilizing the tumour suppressor protein p53. To determine if our observations with D-17 cells applied more universally to canine OS, we examined three other independently isolated canine OS cell lines--Abrams, McKinley and Gracie. Like D-17, the three cell lines expressed p53 proteins that were capable of activating promoters with p53 response elements on their own, and synergistically with Zhangfei. Furthermore, as with D-17 cells, Zhangfei suppressed the growth and UPR-related transcripts in the OS cell lines. Zhangfei also induced the activation of osteocalcin expression, a marker of osteoblast differentiation and triggered programmed cell death. Osteosarcomas are common malignancies in large breeds of dogs. Although there has been dramatic progress in their treatment, these therapies often fail, leading to recurrence of the tumour and metastatic spread. Our results indicate that induction of the expression of Zhangfei in OS, where p53 is functional, may be an effective modality for the treatment of OS.
p53 and Mdm2 act synergistically to maintain cardiac homeostasis and mediate cardiomyocyte cell cycle arrest through a network of microRNAs.

PubMed

Stanley-Hasnain, Shanna; Hauck, Ludger; Grothe, Daniela; Aschar-Sobbi, Roozbeh; Beca, Sanja; Butany, Jagdish; Backx, Peter H; Mak, Tak W; Billia, Filio

2017-01-01

Defining the roadblocks responsible for cell cycle arrest in adult cardiomyocytes lies at the core of developing cardiac regenerative therapies. p53 and Mdm2 are crucial mediators of cell cycle arrest in proliferative cell types, however, little is known about their function in regulating homeostasis and proliferation in terminally differentiated cell types, like cardiomyocytes. To explore this, we generated a cardiac-specific conditional deletion of p53 and Mdm2 (DKO) in adult mice. Herein we describe the development of a dilated cardiomyopathy, in the absence of cardiac hypertrophy. In addition, DKO hearts exhibited a significant increase in cardiomyocyte proliferation. Further evaluation showed that proliferation was mediated by a significant increase in Cdk2 and cyclin E with downregulation of p21 Cip1 and p27 Kip1 . Comparison of miRNA expression profiles from DKO mouse hearts and controls revealed 11 miRNAs that were downregulated in the DKO hearts and enriched for mRNA targets involved in cell cycle regulation. Knockdown of these miRNAs in neonatal rat cardiomyocytes significantly increased cytokinesis with an upregulation in the expression of crucial cell cycle regulators. These results illustrate the importance of the cooperative activities of p53 and Mdm2 in a network of miRNAs that function to impose a barrier against aberrant cardiomyocyte cell cycle re-entry to maintain cardiac homeostasis.
Induction of KLF4 in basal keratinocytes blocks the proliferation-differentiation switch and initiates squamous epithelial dysplasia

PubMed Central

Foster, K. Wade; Liu, Zhaoli; Nail, Clinton D.; Li, Xingnan; Fitzgerald, Thomas J.; Bailey, Sarah K.; Frost, Andra R.; Louro, Iuri D.; Townes, Tim M.; Paterson, Andrew J.; Kudlow, Jeffrey E.; Lobo-Ruppert, Susan M.; Ruppert, J. Michael

2006-01-01

KLF4/GKLF normally functions in differentiating epithelial cells, but also acts as a transforming oncogene in vitro. To examine the role of this zinc finger protein in skin, we expressed the wild-type human allele from inducible and constitutive promoters. When induced in basal keratinocytes KLF4 rapidly abolished the distinctive properties of basal and parabasal epithelial cells. KLF4 caused a transitory apoptotic response and the skin progressed through phases of hyperplasia and dysplasia. By 6 weeks, lesions exhibited nuclear KLF4 and other morphologic and molecular similarities to squamous cell carcinoma in situ. p53 determined the patch size sufficient to establish lesions, as induction in a mosaic pattern produced skin lesions only when p53 was deficient. Compared with p53 wild-type animals, p53 hemizygous animals had early onset of lesions and a pronounced fibrovascular response that included outgrowth of subcutaneous sarcoma. A KLF4-estrogen receptor fusion protein showed tamoxifen-dependent nuclear localization and conditional transformation in vitro. The results suggest that KLF4 can function in the nucleus to induce squamous epithelial dysplasia, and indicate roles for p53 and epithelial-mesenchymal signaling in these early neoplastic lesions. PMID:15674344
Induction of KLF4 in basal keratinocytes blocks the proliferation-differentiation switch and initiates squamous epithelial dysplasia.

PubMed

Foster, K Wade; Liu, Zhaoli; Nail, Clinton D; Li, Xingnan; Fitzgerald, Thomas J; Bailey, Sarah K; Frost, Andra R; Louro, Iuri D; Townes, Tim M; Paterson, Andrew J; Kudlow, Jeffrey E; Lobo-Ruppert, Susan M; Ruppert, J Michael

2005-02-24

KLF4/GKLF normally functions in differentiating epithelial cells, but also acts as a transforming oncogene in vitro. To examine the role of this zinc finger protein in skin, we expressed the wild-type human allele from inducible and constitutive promoters. When induced in basal keratinocytes, KLF4 rapidly abolished the distinctive properties of basal and parabasal epithelial cells. KLF4 caused a transitory apoptotic response and the skin progressed through phases of hyperplasia and dysplasia. By 6 weeks, lesions exhibited nuclear KLF4 and other morphologic and molecular similarities to squamous cell carcinoma in situ. p53 determined the patch size sufficient to establish lesions, as induction in a mosaic pattern produced skin lesions only when p53 was deficient. Compared with p53 wild-type animals, p53 hemizygous animals had early onset of lesions and a pronounced fibrovascular response that included outgrowth of subcutaneous sarcoma. A KLF4-estrogen receptor fusion protein showed tamoxifen-dependent nuclear localization and conditional transformation in vitro. The results suggest that KLF4 can function in the nucleus to induce squamous epithelial dysplasia, and indicate roles for p53 and epithelial-mesenchymal signaling in these early neoplastic lesions.

Schisantherin A Improves Learning and Memory of Mice with D-Galactose-Induced Learning and Memory Impairment through Its Antioxidation and Regulation of p19/p53/p21/Cyclin D1/CDK4/RB Gene Expressions.

PubMed

Liu, Cong; Sun, Weijing; Li, Ning; Gao, Jiaqi; Yu, Chunyan; Wang, Chunmei; Sun, Jinghui; Jing, Shu; Chen, Jianguang; Li, He

2018-05-31

Schisantherin A (SCA) was evaluated for possible function in restoring the learning and memory impairment induced by D-galactose in mice. ICR mice were treated with D-galactose subcutaneously (220 mg·kg -1 ), and followed by SCA in different doses (1.25, 2.50 and 5.00 mg·kg -1 , administered orally) for 42 days. Effects of SCA on learning and memory were examined by step-through tests and Morris water maze tests. The activity of superoxide dismutase (SOD), the content of malondialdehyde (MDA) in the peripheral blood and hippocampus of mice were assayed by water-soluble tetrazolium-1 (WST-1) and thiobarbituric acid (TBA) methods. The contents of 8 hydroxy deoxy guanosine (8-OHdG) in the hippocampus of mice were detected by immunosorbent assay methods, respectively. Quantitative real-time PCR and Western Blot were respectively used to detect the expression of p19, p53, p21, cyclin D1, CDK4 and RB genes, and the phosphorylation of RB in the hippocampus of mice. We found that SCA significantly improved the learning and memory impairment induced by D-galactose in mice. After SCA treatment, SOD activity was increased and the content of MDA was decreased in both peripheral blood and hippocampus of mice. 8-OHDG content was also decreased in the hippocampus of mice. Furthermore, the expression of p19, p53 and p21 genes was reduced and the expression of cyclin D1 and CDK4 and the phosphorylation of RB protein were elevated in the hippocampus. SCA may improve the learning and memory impairment induced by D-galactose by enhancing the antioxidant capacity, and regulating the expression of p19/p53/p21/cyclinD1/CDK4 genes, and the phosphorylation of RB protein in the hippocampus of mice.
Rapamycin regulates the proliferation of Huh7, a hepatocellular carcinoma cell line, by up-regulating p53 expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, Sora; Jeon, Ji-Sook; Ahn, Curie

Rapamycin, a specific inhibitor of mTOR used extensively as an immunosuppressant, has been expanded recently to cancer therapy, because the mTOR signal is known to be up-regulated in various cancer cells including hepatocellular carcinoma (HCC) cells. In spite of extensive efforts to employ mTOR inhibitors as anti-HCC therapy, they have not yet been approved by the FDA. Because of the heterogeneity and complexity of molecular signaling in HCC, suitable biomarkers should be identified or discovered to improve clinical efficacy of mTOR-specific inhibitors to HCC cells. In this study, the effect of rapamycin was investigated on two different HCC cell lines,more » Huh7 cells and HepG2 cells. Rapamycin was found to inhibit the proliferation of Huh7 cells but not of HepG2 cells. Moreover, it was found that rapamycin can up-regulate p53 at the protein level, but not affect its transcript. To understand the critical role of p53 in the rapamycin effect, knock-down experiments were performed using small-interfering RNAs (siRNAs). The anti-proliferative effect of rapamycin on Huh7 cells clearly disappeared after blocking p53 production with siRNA, which indicates that p53 is a critical factor in the anti-proliferative effect of rapamycin in HCC cells. The over-expression system of p53 was also employed to mimic the effect of rapamycin and found that cell proliferation was clearly down-regulated by p53 over-expression. Finally, we found that the extracellular signal-regulated kinase 1/2 (ERK1/2) signal was regulated by p53 whose expression was induced by rapamycin. Overall, this study demonstrates that rapamycin inhibited the proliferation of Huh7 cells by up-regulating the expression of p53 and down-regulating the ERK1/2 signal, indicating that p53 is a useful biomarker for anti-cancer therapy using the specific inhibitor of mTOR signal, rapamycin, against hepatocellular carcinoma cells. - Highlights: • Rapamycin inhibits the proliferation of hepatocellular carcinoma cells depending on the expression of p53. • Rapamycin up-regulates p53 at the protein level, but not affect its transcript. • The up-regulation of p53 expression by rapamycin inhibits ERK signal.« less
Using yeast to determine the functional consequences of mutations in the human p53 tumor suppressor gene: An introductory course-based undergraduate research experience in molecular and cell biology.

PubMed

Hekmat-Scafe, Daria S; Brownell, Sara E; Seawell, Patricia Chandler; Malladi, Shyamala; Imam, Jamie F Conklin; Singla, Veena; Bradon, Nicole; Cyert, Martha S; Stearns, Tim

2017-03-04

The opportunity to engage in scientific research is an important, but often neglected, component of undergraduate training in biology. We describe the curriculum for an innovative, course-based undergraduate research experience (CURE) appropriate for a large, introductory cell and molecular biology laboratory class that leverages students' high level of interest in cancer. The course is highly collaborative and emphasizes the analysis and interpretation of original scientific data. During the course, students work in teams to characterize a collection of mutations in the human p53 tumor suppressor gene via expression and analysis in yeast. Initially, student pairs use both qualitative and quantitative assays to assess the ability of their p53 mutant to activate expression of reporter genes, and they localize their mutation within the p53 structure. Through facilitated discussion, students suggest possible molecular explanations for the transactivation defects displayed by their p53 mutants and propose experiments to test these hypotheses that they execute during the second part of the course. They use a western blot to determine whether mutant p53 levels are reduced, a DNA-binding assay to test whether recognition of any of three p53 target sequences is compromised, and fluorescence microscopy to assay nuclear localization. Students studying the same p53 mutant periodically convene to discuss and interpret their combined data. The course culminates in a poster session during which students present their findings to peers, instructors, and the greater biosciences community. Based on our experience, we provide recommendations for the development of similar large introductory lab courses. © 2016 by The International Union of Biochemistry and Molecular Biology, 45(2):161-178, 2017. © 2016 The International Union of Biochemistry and Molecular Biology.
Using yeast to determine the functional consequences of mutations in the human p53 tumor suppressor gene: An introductory course‐based undergraduate research experience in molecular and cell biology

PubMed Central

Brownell, Sara E.; Seawell, Patricia Chandler; Malladi, Shyamala; Imam, Jamie F. Conklin; Singla, Veena; Bradon, Nicole; Cyert, Martha S.; Stearns, Tim

2016-01-01

Abstract The opportunity to engage in scientific research is an important, but often neglected, component of undergraduate training in biology. We describe the curriculum for an innovative, course‐based undergraduate research experience (CURE) appropriate for a large, introductory cell and molecular biology laboratory class that leverages students′ high level of interest in cancer. The course is highly collaborative and emphasizes the analysis and interpretation of original scientific data. During the course, students work in teams to characterize a collection of mutations in the human p53 tumor suppressor gene via expression and analysis in yeast. Initially, student pairs use both qualitative and quantitative assays to assess the ability of their p53 mutant to activate expression of reporter genes, and they localize their mutation within the p53 structure. Through facilitated discussion, students suggest possible molecular explanations for the transactivation defects displayed by their p53 mutants and propose experiments to test these hypotheses that they execute during the second part of the course. They use a western blot to determine whether mutant p53 levels are reduced, a DNA‐binding assay to test whether recognition of any of three p53 target sequences is compromised, and fluorescence microscopy to assay nuclear localization. Students studying the same p53 mutant periodically convene to discuss and interpret their combined data. The course culminates in a poster session during which students present their findings to peers, instructors, and the greater biosciences community. Based on our experience, we provide recommendations for the development of similar large introductory lab courses. © 2016 by The International Union of Biochemistry and Molecular Biology, 45(2):161–178, 2017. PMID:27873457
p53 mutation and expression in lymphoma.

PubMed Central

Adamson, D. J.; Thompson, W. D.; Dawson, A. A.; Bennett, B.; Haites, N. E.

1995-01-01

Mutation and abnormal expression of p53 was studied in 38 lymphomas [five Hodgkin's disease and 33 non-Hodgkin's lymphoma (NHL)]. CM1 polyclonal antibody was used to detect overexpression of p53. Three missense mutations were characterised in three cases of NHL after screening exons 5-8 of p53 of all the tumours with single-strand conformation polymorphism (SSCP) analysis. Only two out of three tumours with a missense mutation showed abnormal expression of p53 as measured by CM1. Conversely, seven out of nine tumours with positive CM1 staining had no point mutation demonstrated. Overexpression of p53 in the cases of NHL occurred in three out of twenty four low-grade tumours and five out of nine high-grade tumours (Kiel classification). The results suggest that abnormalities of p53 are commoner in high-grade than low-grade NHL, and that positive immunocytochemistry cannot be used to determine which tumours have mutations of p53. Images Figure 1 Figure 2 PMID:7599045
Expression of p53 and selected proliferative markers (Ki-67, MCM3, PCNA, and topoisomerase IIα) in borderline ovarian tumors: Correlation with clinicopathological features.

PubMed

Ciepliński, Klaudiusz; Jóźwik, Maciej; Semczuk-Sikora, Anna; Gogacz, Marek; Lewkowicz, Dorota; Ignatov, Atanas; Semczuk, Andrzej

2018-02-01

The expression of p53 has been studied not only in primary human ovarian carcinomas, but also in borderline ovarian tumors, however, the results were discordant. Expression patterns of proteins involved in cell proliferation and apoptosis have been investigated in various human neoplasms, including female genital tract neoplasms. The aim of this investigation was to assess the staining pattern and immunolocalization of p53 and selected proliferative markers (Ki-67, MCM3, PCNA, and topoisomerase IIα) in borderline ovarian tumors (BOTs). The study group consisted of 42 women who underwent pelvic surgery between 2006-2015. The median patients' age was 46 years. The immunoperoxidase technique was employed using antibodies against p53, Ki-67, MCM3, PCNA, and topoisomerase IIα. For p53, nuclear expression was observed in BOTs, however, cytoplasmatic immunoreactivity was also detected. Altogether, 25 (60%) tumors demonstrated positive p53 immunostaining, including overexpression found in 6 (14%). There were no significant differences in p53 expression between subgroups of clinicopathological variables. Immunoexpression of Ki-67, MCM3, PCNA, and topoisomerase IIα was nuclear. Ki-67 expression was positive in 12 (29%) cases and there was a trend towards a relationship between patients' age and Ki-67 staining (P=0.08). Interestingly, a significantly higher Ki-67 expression was found in tumors of ≥10 cm in diameter compared to smaller tumors (P=0.008). MCM3 expression was detected in 38 (90%) tumors, and PCNA expression in 28 (67%), yet none of clinicopathological factors was related to them. Topoisomerase IIα expression was present in 14 (33%) cases and, interestingly, its significantly higher expression was observed in BOTs of ≥10 cm in diameter compared to smaller tumors (P=0.008). Moreover, Spearman's correlation revealed highly significant positive associations between Ki-67 and topoisomerase IIα (R=0.403, P=0.008) and Ki-67 and MCM3 (R=0.469, P=0.001). We report a high positive immunostaining rate for p53, suggesting a role of TP53 alterations in the development of BOTs in humans. The new finding of higher topoisomerase IIα immunostaining positivity in BOTs of ≥10 cm may be clinically relevant and requires further studies on larger patient groups.
p53 Regulates insulin-like growth factor-I receptor gene expression in uterine serous carcinoma and predicts responsiveness to an insulin-like growth factor-I receptor-directed targeted therapy.

PubMed

Attias-Geva, Zohar; Bentov, Itay; Kidron, Dvora; Amichay, Keren; Sarfstein, Rive; Fishman, Ami; Bruchim, Ilan; Werner, Haim

2012-07-01

The role of the insulin-like growth factors (IGF) in endometrial cancer has been well established. The IGF-I receptor (IGF-IR), which mediates the biological actions of IGF-I, is usually overexpressed in endometrial tumours. Uterine serous carcinoma (USC) constitutes a defined histological category among endometrial cancers. Mutation of the p53 gene appears early in the course of the disease and is considered a key event in the initiation of USC. The aim of the present study was to evaluate the potential interactions between p53 and the IGF-IR in USC. In addition, we investigated the role of p53 as a biomarker in IGF-IR targeted therapies. Immunohistochemical analysis in a collection of 35 USC specimens revealed that IGF-IR is highly expressed in primary and metastatic USC. Likewise, p53 was expressed in 85.7% of primary tumours and 100% of metastases. A significant negative correlation between p53 expression and survival was noticed. In addition, using USC-derived cell lines we provide evidence that p53 regulates IGF-IR gene expression via a mechanism that involves repression of the IGF-IR promoter. We show that the mechanism of action of p53 involves interaction with zinc finger protein Sp1, a potent transactivator of the IGF-IR gene. Finally, we demonstrate that USC tumours overexpressing p53 are more likely to benefit from anti-IGF-IR therapies. In summary, we provide evidence that p53 regulates IGF-IR gene expression in USC cells via a mechanism that involves repression of the IGF-IR promoter. The interplay between the p53 and IGF-I signalling pathways is of major basic and translational relevance. Copyright © 2011 Elsevier Ltd. All rights reserved.
Transcription factor Sox4 is required for PUMA-mediated apoptosis induced by histone deacetylase inhibitor, TSA.

PubMed

Jang, Sang-Min; Kang, Eun-Jin; Kim, Jung-Woong; Kim, Chul-Hong; An, Joo-Hee; Choi, Kyung-Hee

2013-08-23

PUMA is a crucial regulator of apoptotic cell death mediated by p53-dependent and p53-independent mechanisms. In many cancer cells, PUMA expression is induced in response to DNA-damaging reagent in a p53-dependent manner. However, few studies have investigated transcription factors that lead to the induction of PUMA expression via p53-independent apoptotic signaling. In this study, we found that the transcription factor Sox4 increased PUMA expression in response to trichostatin A (TSA), a histone deacetylase inhibitor in the p53-null human lung cancer cell line H1299. Ectopic expression of Sox4 led to the induction of PUMA expression at the mRNA and protein levels, and TSA-mediated up-regulation of PUMA transcription was repressed by the knockdown of Sox4. Using luciferase assays and chromatin immunoprecipitation, we also determined that Sox4 recruits p300 on the PUMA promoter region and increases PUMA gene expression in response to TSA treatment. Taken together, these results suggest that Sox4 is required for p53-independent apoptotic cell death mediated by PUMA induction via TSA treatment. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.
Proteasome inhibition mediates p53 reactivation and anti-cancer activity of 6-gingerol in cervical cancer cells.

PubMed

Rastogi, Namrata; Duggal, Shivali; Singh, Shailendra Kumar; Porwal, Konica; Srivastava, Vikas Kumar; Maurya, Rakesh; Bhatt, M L B; Mishra, Durga Prasad

2015-12-22

Human papilloma virus (HPV) expressing E6 and E7 oncoproteins, is known to inactivate the tumor suppressor p53 through proteasomal degradation in cervical cancers. Therefore, use of small molecules for inhibition of proteasome function and induction of p53 reactivation is a promising strategy for induction of apoptosis in cervical cancer cells. The polyphenolic alkanone, 6-Gingerol (6G), present in the pungent extracts of ginger (Zingiber officinale Roscoe) has shown potent anti-tumorigenic and pro-apoptotic activities against a variety of cancers. In this study we explored the molecular mechanism of action of 6G in human cervical cancer cells in vitro and in vivo. 6G potently inhibited proliferation of the HPV positive cervical cancer cells. 6G was found to: (i) inhibit the chymotrypsin activity of proteasomes, (ii) induce reactivation of p53, (iii) increase levels of p21, (iv) induce DNA damage and G2/M cell cycle arrest, (v) alter expression levels of p53-associated apoptotic markers like, cleaved caspase-3 and PARP, and (vi) potentiate the cytotoxicity of cisplatin. 6G treatment induced significant reduction of tumor volume, tumor weight, proteasome inhibition and p53 accumulation in HeLa xenograft tumor cells in vivo. The 6G treatment was devoid of toxic effects as it did not affect body weights, hematological and osteogenic parameters. Taken together, our data underscores the therapeutic and chemosensitizing effects of 6G in the management and treatment of cervical cancer.
Proteasome inhibition mediates p53 reactivation and anti-cancer activity of 6-Gingerol in cervical cancer cells

PubMed Central

Rastogi, Namrata; Duggal, Shivali; Singh, Shailendra Kumar; Porwal, Konica; Srivastava, Vikas Kumar; Maurya, Rakesh; Bhatt, Madan L.B.; Mishra, Durga Prasad

2015-01-01

Human papilloma virus (HPV) expressing E6 and E7 oncoproteins, is known to inactivate the tumor suppressor p53 through proteasomal degradation in cervical cancers. Therefore, use of small molecules for inhibition of proteasome function and induction of p53 reactivation is a promising strategy for induction of apoptosis in cervical cancer cells. The polyphenolic alkanone, 6-Gingerol (6G), present in the pungent extracts of ginger (Zingiber officinale Roscoe) has shown potent anti-tumorigenic and pro-apoptotic activities against a variety of cancers. In this study we explored the molecular mechanism of action of 6G in human cervical cancer cells in vitro and in vivo. 6G potently inhibited proliferation of the HPV positive cervical cancer cells. 6G was found to: (i) inhibit the chymotrypsin activity of proteasomes, (ii) induce reactivation of p53, (iii) increase levels of p21, (iv) induce DNA damage and G2/M cell cycle arrest, (v) alter expression levels of p53-associated apoptotic markers like, cleaved caspase-3 and PARP, and (vi) potentiate the cytotoxicity of cisplatin. 6G treatment induced significant reduction of tumor volume, tumor weight, proteasome inhibition and p53 accumulation in HeLa xenograft tumor cells in vivo. The 6G treatment was devoid of toxic effects as it did not affect body weights, hematological and osteogenic parameters. Taken together, our data underscores the therapeutic and chemosensitizing effects of 6G in the management and treatment of cervical cancer. PMID:26621832
Nucleostemin rejuvenates cardiac progenitor cells and antagonizes myocardial aging.

PubMed

Hariharan, Nirmala; Quijada, Pearl; Mohsin, Sadia; Joyo, Anya; Samse, Kaitlen; Monsanto, Megan; De La Torre, Andrea; Avitabile, Daniele; Ormachea, Lucia; McGregor, Michael J; Tsai, Emily J; Sussman, Mark A

2015-01-20

Functional decline in stem cell-mediated regeneration contributes to aging associated with cellular senescence in c-kit+ cardiac progenitor cells (CPCs). Clinical implementation of CPC-based therapy in elderly patients would benefit tremendously from understanding molecular characteristics of senescence to antagonize aging. Nucleostemin (NS) is a nucleolar protein regulating stem cell proliferation and pluripotency. This study sought to demonstrate that NS preserves characteristics associated with "stemness" in CPCs and antagonizes myocardial senescence and aging. CPCs isolated from human fetal (fetal human cardiac progenitor cell [FhCPC]) and adult failing (adult human cardiac progenitor cell [AhCPC]) hearts, as well as young (young cardiac progenitor cell [YCPC]) and old mice (old cardiac progenitor cell [OCPC]), were studied for senescence characteristics and NS expression. Heterozygous knockout mice with 1 functional allele of NS (NS+/-) were used to demonstrate that NS preserves myocardial structure and function and slows characteristics of aging. NS expression is decreased in AhCPCs relative to FhCPCs, correlating with lowered proliferation potential and shortened telomere length. AhCPC characteristics resemble those of OCPCs, which have a phenotype induced by NS silencing, resulting in cell flattening, senescence, multinucleated cells, decreased S-phase progression, diminished expression of stemness markers, and up-regulation of p53 and p16. CPC senescence resulting from NS loss is partially p53 dependent and is rescued by concurrent silencing of p53. Mechanistically, NS induction correlates with Pim-1 kinase-mediated stabilization of c-Myc. Engineering OCPCs and AhCPCs to overexpress NS decreases senescent and multinucleated cells, restores morphology, and antagonizes senescence, thereby preserving phenotypic properties of "stemness." Early cardiac aging with a decline in cardiac function, an increase in senescence markers p53 and p16, telomere attrition, and accompanied CPC exhaustion is evident in NS+/- mice. Youthful properties and antagonism of senescence in CPCs and the myocardium are consistent with a role for NS downstream from Pim-1 signaling that enhances cardiac regeneration. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Rigor of cell fate decision by variable p53 pulses and roles of cooperative gene expression by p53

PubMed Central

Murakami, Yohei; Takada, Shoji

2012-01-01

Upon DNA damage, the cell fate decision between survival and apoptosis is largely regulated by p53-related networks. Recent experiments found a series of discrete p53 pulses in individual cells, which led to the hypothesis that the cell fate decision upon DNA damage is controlled by counting the number of p53 pulses. Under this hypothesis, Sun et al. (2009) modeled the Bax activation switch in the apoptosis signal transduction pathway that can rigorously “count” the number of uniform p53 pulses. Based on experimental evidence, here we use variable p53 pulses with Sun et al.’s model to investigate how the variability in p53 pulses affects the rigor of the cell fate decision by the pulse number. Our calculations showed that the experimentally anticipated variability in the pulse sizes reduces the rigor of the cell fate decision. In addition, we tested the roles of the cooperativity in PUMA expression by p53, finding that lower cooperativity is plausible for more rigorous cell fate decision. This is because the variability in the p53 pulse height is more amplified in PUMA expressions with more cooperative cases. PMID:27857606
Inhibition of SIRT1 Catalytic Activity Increases p53 Acetylation but Does Not Alter Cell Survival following DNA Damage

PubMed Central

Solomon, Jonathan M.; Pasupuleti, Rao; Xu, Lei; McDonagh, Thomas; Curtis, Rory; DiStefano, Peter S.; Huber, L. Julie

2006-01-01

Human SIRT1 is an enzyme that deacetylates the p53 tumor suppressor protein and has been suggested to modulate p53-dependent functions including DNA damage-induced cell death. In this report, we used EX-527, a novel, potent, and specific small-molecule inhibitor of SIRT1 catalytic activity to examine the role of SIRT1 in p53 acetylation and cell survival after DNA damage. Treatment with EX-527 dramatically increased acetylation at lysine 382 of p53 after different types of DNA damage in primary human mammary epithelial cells and several cell lines. Significantly, inhibition of SIRT1 catalytic activity by EX-527 had no effect on cell growth, viability, or p53-controlled gene expression in cells treated with etoposide. Acetyl-p53 was also increased by the histone deacetylase (HDAC) class I/II inhibitor trichostatin A (TSA). EX-527 and TSA acted synergistically to increase acetyl-p53 levels, confirming that p53 acetylation is regulated by both SIRT1 and HDACs. While TSA alone reduced cell survival after DNA damage, the combination of EX-527 and TSA had no further effect on cell viability and growth. These results show that, although SIRT1 deacetylates p53, this does not play a role in cell survival following DNA damage in certain cell lines and primary human mammary epithelial cells. PMID:16354677
p53 mediates bcl-2 phosphorylation and apoptosis via activation of the Cdc42/JNK1 pathway.

PubMed

Thomas, A; Giesler, T; White, E

2000-11-02

A member of the small G protein family, cdc42, was isolated from a screen undertaken to identify p53-inducible genes during apoptosis in primary baby rat kidney (BRK) cells transformed with E1A and a temperature-sensitive mutant p53 using a PCR-based subtractive hybridization method. Cdc42 is a GTPase that belongs to the Rho/Rac subfamily of Ras-like GTPases. In response to external stimuli, Cdc42 is known to transduce signals to regulate the organization of the actin cytoskeleton, induce DNA synthesis in quiescent fibroblasts, and promote apoptosis in neuronal and immune cells. In this study, we have demonstrated that cdc42 mRNA and protein were up-regulated in the presence of wild-type p53 in BRK cells, followed by cytoplasmic to plasma membrane translocation of Cdc42. Overexpression of Cdc42 in the presence of a dominant-negative mutant p53 induced apoptosis rapidly, indicating that Cdc42 functions downstream of p53. Furthermore, stable expression of a dominant-negative mutant of Cdc42 partially inhibited p53-mediated apoptosis. The Bcl-2 family members Bcl-xL, and the adenovirus protein E1B 19K, inhibited Cdc42-mediated apoptosis, whereas Bcl-2 did not. We provide evidence that PAK1 and JNK1 may play a role downstream of Cdc42 to transduce its apoptotic signal. Cdc42/PAK1 activates JNK1-induced phosphorylation of Bcl-2, thereby inactivating its function, and that a phosphorylation resistant mutant (Bcl-2S70,87A,T56,74A) gains the ability to inhibit Cdc42- and p53-mediated apoptosis. Thus, one mechanism by which p53 promotes apoptosis is through activation of Cdc42 and inactivation of Bcl-2.
LEF1 is preferentially expressed in the tubal-peritoneal junctions and is a reliable marker of tubal intraepithelial lesions

PubMed Central

Schmoeckel, Elisa; Odai-Afotey, Ashley A.; Schleiβheimer, Michael; Rottmann, Miriam; Flesken-Nikitin, Andrea; Ellenson, Lora H.; Kirchner, Thomas; Mayr, Doris; Nikitin, Alexander Yu.

2017-01-01

Recently it has been reported that serous tubal intraepithelial carcinoma (STIC), the likely precursor of ovarian/extra-uterine high-grade serous carcinoma, are frequently located in the vicinity of tubal-peritoneal junctions, consistent with the cancer-prone features of many epithelial transitional regions. To test if p53 (aka TP53)-signatures and secretory cell outgrowths (SCOUTs) also localize to tubal-peritoneal junctions, we examined these lesions in the fallopian tubes of patients undergoing salpingo-oophorectomy for sporadic high-grade serous carcinomas or as a prophylactic procedure for carriers of familial BRCA1 or 2 mutations. STICs were located closest to the tubal-peritoneal junctions with an average distance of 1.31 mm, while SCOUTs were not detected in the fimbriated end of the fallopian tube. Since many epithelial transitional regions contain stem cells, we also determined the expression of stem cell markers in the normal fallopian tube, tubal intraepithelial lesions and high-grade serous carcinomas. Of those, LEF1 was consistently expressed in the tubal-peritoneal junctions and all lesions, independent of p53 status. All SCOUTs demonstrated strong nuclear expression of β-catenin consistent with the LEF1 participation in the canonical WNT pathway. However, β-catenin was preferentially located in the cytoplasm of cells comprising STICs and p53 signatures, suggesting WNT-independent function of LEF1 in those lesions. Both frequency of LEF1 expression and β-catenin nuclear expression correlated with the worst 5 year patient survival, supporting important role of both proteins in high-grade serous carcinoma. Taken together, our findings suggest the existence of stem cell niche within the tubal-peritoneal junctions. Furthermore, they support the notion that the pathogenesis of SCOUTs is distinct from that of STICs and p53 signatures. The location and discrete patterns of LEF1 and β-catenin expression may serve as highly sensitive and reliable ancillary markers for the detection and differential diagnosis of tubal intraepithelial lesions. PMID:28664938
A novel small molecule inhibitor of MDM2-p53 (APG-115) enhances radiosensitivity of gastric adenocarcinoma.

PubMed

Yi, Hanjie; Yan, Xianglei; Luo, Qiuyun; Yuan, Luping; Li, Baoxia; Pan, Wentao; Zhang, Lin; Chen, Haibo; Wang, Jing; Zhang, Yubin; Zhai, Yifan; Qiu, Miao-Zhen; Yang, Da-Jun

2018-05-02

Gastric cancer is the leading cause of cancer related death worldwide. Radiation alone or combined with chemotherapy plays important role in locally advanced and metastatic gastric adenocarcinoma. MDM2-p53 interaction and downstream signaling affect cellular response to DNA damage which leads to cell cycle arrest and apoptosis. Therefore, restoring p53 function by inhibiting its interaction with MDM2 is a promising therapeutic strategy for cancer. APG-115 is a novel small molecule inhibitor which blocks the interaction of MDM2 and p53. In this study, we investigated that the radiosensitivity of APG-115 in gastric adenocarcinoma in vitro and in vivo. The role of APG-115 in six gastric cancer cells viability in vitro was determined by CCK-8 assay. The expression level of MDM2, p21, PUMA and BAX in AGS and MKN45 cell lines was measured via real-time PCR (RT-PCR). The function of treatment groups on cell cycle and cell apoptosis were detected through Flow Cytometry assay. Clonogenic assays were used to measure the radiosensitivity of APG-115 in p53 wild type gastric cancer cell lines. Western blot was conducted to detect the protein expressions of mdm2-p53 signal pathway. Xenograft models in nude mice were established to explore the radiosensitivity role of APG-115 in gastric cancer cells in vivo. We found that radiosensitization by APG-115 occurred in p53 wild-type gastric cancer cells. Increasing apoptosis and cell cycle arrest was observed after administration of APG-115 and radiation. Radiosensitivity of APG-115 was mainly dependent on MDM2-p53 signal pathway. In vivo, APG-115 combined with radiation decreased xenograft tumor growth much more significantly than either single treatment. Moreover, the number of proliferating cells (Ki-67) significantly decreased in combination group compared with single treatment group. In summary, we found that combination of MDM2-p53 inhibitor (APG-115) and radiotherapy can enhance antitumor effect both in vitro and in vivo. This is the first report on radiosensitivity of APG-115 which shed light on clinical trial of the combination therapy of radiation with APG-115 in gastric adenocarcinoma.
Characterization of enzymatic properties of human ribonucleotide reductase holoenzyme reconstituted in vitro from hRRM1, hRRM2, and p53R2 subunits.

PubMed

Qiu, Weihua; Zhou, Bingsen; Darwish, Dana; Shao, Jimin; Yen, Yun

2006-02-10

Ribonucleotide reductase (RR) is a highly regulated enzyme in the deoxyribonucleotide synthesis pathway. RR is responsible for the de novo conversion of ribonucleoside diphosphates to deoxyribonucleoside diphosphates, which are essential for DNA synthesis and repair. Besides two subunits, hRRM1 and hRRM2, p53R2 is a newly identified member of RR family that is induced by ultraviolet light in a p53-dependent manner. To understand the molecular interaction of RR subunits, we employed a eukaryotic expression system to express and purify all three subunits. After in vitro reconstitution, the results of [(3)H]CDP reduction assay showed that both eukaryotic recombinant hRRM2 and p53R2 proteins could interact with hRRM1 to form functional RR holoenzyme. The reconstituted RR activity was time-dependent and the reaction rate reached the plateau phase after 40min incubation. No matter the concentration, RR holoenzyme reconstituted from p53R2 and hRRM1 could only achieve about 40-75% kinetic activity of that from hRRM2 and hRRM1. The synthetic C-terminal heptapeptide competition assays confirmed that hRRM2 and p53R2 share the same binding site on hRRM1, but the binding site on hRRM1 demonstrated higher affinity for hRRM2 than for p53R2. In allosteric regulation assay, the effect of activation or inhibition of hRRM1 with ATP or dATP suggested that these effectors could regulate RR activity independent of different RR small subunits. Taken together, the eukaryotic expression system RR holoenzyme will provide a very useful tool to understand the molecular mechanisms of RR activity and the interactions of its subunits.
The Human ARF Cell Cycle Regulatory Gene Promoter Is a CpG Island Which Can Be Silenced by DNA Methylation and Down-Regulated by Wild-Type p53

PubMed Central

Robertson, Keith D.; Jones, Peter A.

1998-01-01

The INK4a/ARF locus encodes two proteins involved in tumor suppression in a manner virtually unique in mammalian cells. Distinct first exons, driven from separate promoters, splice onto a common exon 2 and 3 but utilize different reading frames to produce two completely distinct proteins, both of which play roles in cell cycle control. INK4a, a critical element of the retinoblastoma gene pathway, binds to and inhibits the activities of CDK4 and CDK6, while ARF, a critical element of the p53 pathway, increases the level of functional p53 via interaction with MDM2. Here we clone and characterize the promoter of the human ARF gene and show that it is a CpG island characteristic of a housekeeping gene which contains numerous Sp1 sites. Both ARF and INK4a are coordinately expressed in cells except when their promoter regions become de novo methylated. In one of these situations, ARF transcription could be reactivated by treatment with the DNA methylation inhibitor 5-aza-2′-deoxycytidine, and the reactivation kinetics of ARF and INK4a were found to differ slightly in a cell line in which both genes were silenced by methylation. The ARF promoter was also found to be highly responsive to E2F1 expression, in keeping with previous results at the RNA level. Lastly, transcription from the ARF promoter was down-regulated by wild-type p53 expression, and the magnitude of the effect correlated with the status of the endogenous p53 gene. This finding points to the existence of an autoregulatory feedback loop between p53, MDM2, and ARF, aimed at keeping p53 levels in check. PMID:9774662
An analysis of microvessel density, androgen receptor, p53 and HER-2/neu expression and Gleason score in prostate cancer . preliminary results and therapeutic implications.

PubMed

Mydlo, J H; Kral, J G; Volpe, M; Axotis, C; Macchia, R J; Pertschuk, L P

1998-01-01

To investigate relationships between microvessel density (MVD), androgen receptors (AR), mutant p53 and HER-2/neu expression and Gleason score (GS) to further understand the tumor biology of prostate cancer (CAP). Slides of CAP from patients who underwent radical prostatectomy or channel transurethral resection of the prostate (TURP) were tested for androgen receptors by immunocytochemical assay and MVD was analyzed by staining with antibodies to the endothelial cell membrane molecule PECAM-1/CD-31. The p53 monoclonal antibody D07 and HER-2 9G6 mouse monoclonal antibody were used to assess p53 and HER-2/neu expression, respectively. The results were correlated with GS and clinical stage by multivariate analysis. We found a fourfold greater expression of MVD in prostate cancer specimens compared to neighboring normal prostate tissue. We observed a greater concentration of MVD in the higher Gleason scores (r = 0.40, p = 0. 06), and a correlation of Gleason score with mutant p53 expression (r = 0.57, p <0.05). We did not observe any associations between AR or HER-2/neu to Gleason score. More than half of the patients with specimens with 50% or greater expression of mutant p53 were in stage D2 (T4NxM1b) at the time of biopsy. We observed a correlation between mutant p53 and GS, and a greater concentration of MVD in the higher GS. Since the neovascularity of prostate tumors can be attenuated by radiation and hormones, while mutant p53 may confer resistance to such treatment, it appears that p53 expression may also play an important role in addition to angiogenesis in the virulence of prostate cancer. These data may aid in allocating patients to different treatment modalities.
Notch1 Signaling Sensitizes Tumor Necrosis Factor-related Apoptosis-inducing Ligand-induced Apoptosis in Human Hepatocellular Carcinoma Cells by Inhibiting Akt/Hdm2-mediated p53 Degradation and Up-regulating p53-dependent DR5 Expression*

PubMed Central

Wang, Chunmei; Qi, Runzi; Li, Nan; Wang, Zhengxin; An, Huazhang; Zhang, Qinghua; Yu, Yizhi; Cao, Xuetao

2009-01-01

Notch signaling plays a critical role in regulating cell proliferation, differentiation, and apoptosis. Our previous study showed that overexpression of Notch1 could inhibit human hepatocellular carcinoma (HCC) cell growth by arresting the cell cycle and inducing apoptosis. HCC cells are resistant to apoptotic induction by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), so new therapeutic approaches have been explored to sensitize HCC cells to TRAIL-induced apoptosis. We are wondering whether and how Notch1 signaling can enhance the sensitivity of HCC cells to TRAIL-induced apoptosis. In this study, we found that overexpression of ICN, the constitutive activated form of Notch1, up-regulated p53 protein expression in HCC cells by inhibiting proteasome degradation. p53 up-regulation was further observed in human primary hepatocellular carcinoma cells after activation of Notch signaling. Inhibition of the Akt/Hdm2 pathway by Notch1 signaling was responsible for the suppression of p53 proteasomal degradation, thus contributing to the Notch1 signaling-mediated up-regulation of p53 expression. Accordingly, Notch1 signaling could make HCC cells more sensitive to TRAIL-induced apoptosis, whereas Notch1 signaling lost the synergistic promotion of TRAIL-induced apoptosis in p53-silenced HepG2 HCC cells and p53-defective Hep3B HCC cells. The data suggest that enhancement of TRAIL-induced apoptosis by Notch1 signaling is dependent upon p53 up-regulation. Furthermore, Notch1 signaling could enhance DR5 expression in a p53-dependent manner. Taken together, Notch1 signaling sensitizes TRAIL-induced apoptosis in HCC cells by inhibiting Akt/Hdm2-mediated p53 degradation and up-regulating p53-dependent DR5 expression. Thus, our results suggest that activation of Notch1 signaling may be a promising approach to improve the therapeutic efficacy of TRAIL-resistant HCC. PMID:19376776

p53 prevents progression of nevi to melanoma predominantly through cell cycle regulation

PubMed Central

Terzian, Tamara; Torchia, Enrique C.; Dai, Daisy; Robinson, Steven E.; Murao, Kazutoshi; Stiegmann, Regan A.; Gonzalez, Victoria; Boyle, Glen M.; Powell, Marianne B.; Pollock, Pamela M.; Lozano, Guillermina; Robinson, William A.; Roop, Dennis R.; Box, Neil F.

2011-01-01

p53 is the central member of a critical tumor suppressor pathway in virtually all tumor types, where it is silenced mainly by missense mutations. In melanoma, p53 predominantly remains wild type, thus its role has been neglected. To study the effect of p53 on melanocyte function and melanomagenesis, we crossed the ‘high-p53’ Mdm4+/− mouse to the well-established TP-ras0/+ murine melanoma progression model. After treatment with the carcinogen dimethylbenzanthracene (DMBA), TP-ras0/+ mice on the Mdm4+/− background developed fewer tumors with a delay in the age of onset of melanomas compared to TP-ras0/+ mice. Furthermore, we observed a dramatic decrease in tumor growth, lack of metastasis with increased survival of TP-ras0/+: Mdm4+/− mice. Thus, p53 effectively prevented the conversion of small benign tumors to malignant and metastatic melanoma. p53 activation in cultured primary melanocyte and melanoma cell lines using Nutlin-3, a specific Mdm2 antagonist, supported these findings. Moreover, global gene expression and network analysis of Nutlin-3-treated primary human melanocytes indicated that cell cycle regulation through the p21WAF1/CIP1 signaling network may be the key anti-melanomagenic activity of p53. PMID:20849464
The organization and expression of the mdm2 gene.

PubMed

de Oca Luna, R M; Tabor, A D; Eberspaecher, H; Hulboy, D L; Worth, L L; Colman, M S; Finlay, C A; Lozano, G

1996-05-01

The mdm2 gene encodes a zinc finger protein that negatively regulates p53 function by binding and masking the p53 transcriptional activation domain. Two different promoters control expression of mdm2, one of which is also transactivated by p53. We cloned and characterized the mdm2 gene from a murine 129 library. It contained at least 12 exons and spanned approximately 25 kb of DNA. Sequencing of the mdm2 gene revealed three nucleotide differences that resulted in amino acid substitutions in the previously published mdm2 sequence. Sequencing of normal BalbC/J DNA and the original cosmid clone isolated from the 3T3DM cell line revealed that they are identical, suggesting that the published sequence is in error at these three positions. In addition, we analyzed the expression pattern of mdm2 and found ubiquitous low-level expression throughout embryo development and in adult tissues. Analysis of mRNA from numerous tissues for several mdm2 spliced variants that had been identified in the transformed 3T3DM cell line revealed that these variants could not be detected in the developing embryo or in adult tissues.
Arsenite induced poly(ADP-ribosyl)ation of tumor suppressor P53 in human skin keratinocytes as a possible mechanism for carcinogenesis associated with arsenic exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komissarova, Elena V.; Rossman, Toby G., E-mail: toby.rossman@nyumc.or

2010-03-15

Arsenite is an environmental pollutant. Exposure to inorganic arsenic in drinking water is associated with elevated cancer risk, especially in skin. Arsenite alone does not cause skin cancer in animals, but arsenite can enhance the carcinogenicity of solar UV. Arsenite is not a significant mutagen at non-toxic concentrations, but it enhances the mutagenicity of other carcinogens. The tumor suppressor protein P53 and nuclear enzyme PARP-1 are both key players in DNA damage response. This laboratory demonstrated earlier that in cells treated with arsenite, the P53-dependent increase in p21{sup WAF1/CIP1} expression, normally a block to cell cycle progression after DNA damage,more » is deficient. Here we show that although long-term exposure of human keratinocytes (HaCaT) to a nontoxic concentration (0.1 muM) of arsenite decreases the level of global protein poly(ADP-ribosyl)ation, it increases poly(ADP-ribosyl)ation of P53 protein and PARP-1 protein abundance. We also demonstrate that exposure to 0.1 muM arsenite depresses the constitutive expression of p21 mRNA and P21 protein in HaCaT cells. Poly(ADP-ribosyl)ation of P53 is reported to block its activation, DNA binding and its functioning as a transcription factor. Our results suggest that arsenite's interference with activation of P53 via poly(ADP-ribosyl)ation may play a role in the comutagenic and cocarcinogenic effects of arsenite.« less
Che-1 gene silencing induces osteosarcoma cell apoptosis by inhibiting mutant p53 expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ming; Wang, Dan, E-mail: danwangwdd@163.com; Li, Ning

2016-04-22

The transcriptional cofactor Che-1 is an RNA polymerase II (Pol II) which is involved in tumorigenesis, such as breast cancer and multiple myeloma. Che-1 can also regulate mutant p53 expression, which plays roles in many types of cancer. In this study, we aimed to investigate the effects and specific mechanism of Che-1 in the regulation of osteosarcoma (OS) cell growth. We found that Che-1 is highly expressed in several kinds of OS cells compared with osteoblast hFOB1.19 cells. MTT and flow cytometry assays showed that Che-1 depletion by siRNA markedly suppressed MG-63 and U2OS cell proliferation and promoted apoptosis. The chromatinmore » immunoprecipitation (ChIP) assay verified the presence of Che-1 on the p53 promoter in MG-63 and U2OS cells carrying mutant p53. Further studies showed that Che-1 depletion inhibited mutant p53 expression. Notably, our study showed that the loss of Che-1 inhibits proliferation and promotes apoptosis in MG-63 cells by decreasing the level of mutant p53. Therefore, these findings open the possibility that silencing of Che-1 will have therapeutic benefit in OS. - Highlights: • Che-1 is highly expressed in several kinds of OS cells. • Che-1 depletion suppressed MG-63 and U2OS cell growth. • Che-1 is existed in the p53 promoter in MG-63 and U2OS cells. • Che-1 depletion inhibited mutant p53 expression. • Che-1 depletion inhibits cell growth by decreasing the level of mutant p53.« less
[The expression of p53, MDM2 and Ref1 gene in cultured retina neurons of SD rats treated with vitamin B1 and/or elevated pressure].

PubMed

Yang, Zhikuan; Ge, Jian; Yin, Wei; Shen, Huangxuan; Liu, Haiquan; Guo, Yan

2004-12-01

To investigate the expression of p53, MDM2 and Ref1 gene in cultured retina neurons of SD rats treated with Vitamin B1 and (or) elevated pressure. The retinal neuron of postnatal SD rats were cultured in vivo, the elevated pressure was produced after 7 days, and the total RNA was extracted after another 2 days, expression of p53, MDM2 and Ref1 gene were analyzed with RT-PCR. The expression level of p53 and MDM2 gene were increased in elevated pressure group, normal with Ref1 gene expression. But the expression of p53 and MDM2 gene were decreased significantly in elevated pressure group treated with vitamine B1 compare to the elevated group. Apoptosis seem to be a mechanism of cell death in retinal neurons of SD rats with elevated pressure.Vitamine B1 have protect effects against elevated pressure.
Depletion of Securin Induces Senescence After Irradiation and Enhances Radiosensitivity in Human Cancer Cells Regardless of Functional p53 Expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Wenshu; Yu Yichu; Lee Yijang

2010-06-01

Purpose: Radiotherapy is one of the best choices for cancer treatment. However, various tumor cells exhibit resistance to irradiation-induced apoptosis. The development of new strategies to trigger cancer cell death besides apoptosis is necessary. This study investigated the role of securin in radiation-induced apoptosis and senescence in human cancer cells. Methods and Materials: Cell survival was determined using clonogenic assays. Western blot analysis was used to analyze levels of securin, caspase-3, PARP, p53, p21, Rb, gamma-H2AX, and phospho-Chk2. Senescent cells were analyzed using a beta-galactosidase staining assay. A securin-expressed vector (pcDNA-securin) was stably transfected into securin-null HCT116 cells. Securin genemore » knockdown was performed by small interfering RNA and small hairpin RNA in HCT116 and MDA-MB-231 cells, respectively. Results: Radiation was found to induce apoptosis in securin wild type HCT116 cells but induced senescence in securin-null cells. Restoration of securin reduced senescence and increased cell survival in securin-null HCT116 cells after irradiation. Radiation-induced gamma-H2AX and Chk2 phosphorylation were induced transiently in securin-wild-type cells but exhibited sustained activation in securin-null cells. Securin gene knockdown switches irradiation-induced apoptosis to senescence in both HCT116 p53-null and MDA-MB-231 cells. Conclusions: Our results demonstrated that the level of securin expression plays a determining role in the radiosensitivity and fate of cells. Depletion of securin impairs DNA repair after irradiation, increasing DNA damage and promoting senescence in the residual surviving cells regardless of functional p53 expression. The knockdown of securin may contribute to a novel radiotherapy protocol for the treatment of human cancer cells that are resistant to irradiation.« less
Positive expression of p53, c-erbB2 and MRP proteins is correlated with survival rates of NSCLC patients.

PubMed

Xu, Yujin; Wang, Liancong; Zheng, Xiao; Liu, Guan; Wang, Yuezhen; Lai, Xiaojing; Li, Jianqiang

2013-05-01

The incidence of lung cancer is one of the leading causes of mortality. This study aimed to investigate the prognostic and predictive importance of p53, c-erbB2 and multidrug resistance proteins (MRP) expression and its correlation with clinicopathological characteristics of patients with non-small cell lung cancer (NSCLC). Expression of p53, c-erbB2 and MRP proteins in 152 tumor samples from resected primary NSCLCs was detected by immunohistochemical staining. The correlation of proteins, survival and clinicopathological characteristics was investigated in 152 patients undergoing potentially curative surgery. The positive rates of p53, c-erbB2 and MRP expression were 53.9 (82/152), 44.1 (67/152) and 43.4% (66/152), respectively. Overall survival rates of patients were markedly correlated with the overexpression of p53, c-erbB2 and MRP proteins. One, 2- and 3-year survival rates of patients exhibiting a positive expression of these proteins were 72.6, 54.8 and 32.2%, respectively. These rates were lower compared with those of patients with a negative expression of these proteins (92.1, 78.5 and 63.4%) (P=0.02, 0.01 or 0.00, respectively). Results of Cox's regression analysis showed that c-erbB2 expression and cell differentiation were independent prognostic factors in patients with NSCLC. These findings suggest that the positive expression of p53, c-erbB2 and MRP proteins is correlated with the survival rates of NSCLC patients. Detection of positive p53, c-erbB2 and MRP expression may be a useful predictive indicator of prognosis. Positive c-erbB2 expression is an independent prognostic factor, with a potential to be used as a predictive indicator of chemotherapy efficacy in NSCLC patients.
FAP-1 and NF-κB expressions in oral squamous cell carcinoma as potential markers for chemo-radio sensitivity and prognosis.

PubMed

Nariai, Y; Mishima, K; Yoshimura, Y; Sekine, J

2011-04-01

This study was designed to investigate the feasibility of using Fas-associated phosphatase-1 (FAP-1), nuclear factor kappa B (NF-κB) and p53 as markers for chemo-radio sensitivity in oral squamous cell carcinoma (OSCC). FAP-1 plays a role as an anti-apoptotic factor through Fas-dependent apoptosis after chemo-radiotherapy. NF-κB and p53 might be involved in modulation of FAP-1 expression. FAP-1, NF-κB and p53 expression were immunohistochemically examined using biopsy specimens in 50 OSCC patients treated with chemotherapy and/or radiotherapy. FAP-1 was expressed in 52%, NF-κB in 52% and p53 in 46% of patients. There was no significant difference in FAP-1, p53 or NF-κB expression according to the clinicopathological features. No correlation was found among FAP-1, p53 or NF-κB expression. FAP-1-positive cases showed a poorer survival rate than FAP-1-negative cases (P = 0.0409) and NF-κB-positive cases showed a poorer survival rate than NF-κB-negative cases (P = 0.0018). Multivariate analysis showed that FAP-1 expression, NF-κB expression, clinical stage and age were significant independent variables for survival (clinical stage: P = 0.0016; age: P = 0.0016; NF-κB: P = 0.0314; FAP-1: P = 0.0366). These results suggest that FAP-1 and NF-κB might play a role as chemo-radioresistant factor during chemo-radiotherapy, and FAP-1 and NF-κB expression in OSCC would be feasible markers for chemo-radio sensitivity and prognosis. Copyright © 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Immunohistochemical study of p53 and proliferating cell nuclear antigen expression in odontogenic keratocyst and periapical cyst.

PubMed

Sajeevan, Thara Purath; Saraswathi, Tillai Rajasekaran; Ranganathan, Kannan; Joshua, Elizabeth; Rao, Uma Devi K

2014-07-01

p53 protein is a product of p53 gene, which is now classified as a tumor suppressor gene. The gene is a frequent target for mutation, being seen as a common step in the pathogenesis of many human cancers. Proliferating cell nuclear antigen (PCNA) is an auxiliary protein of DNA polymerase delta and plays a critical role in initiation of cell proliferation. The aim of this study is to assess and compare the expression of p53 and PCNA in lining epithelium of odontogenic keratocyst (OKC) and periapical cyst (PA). A total of 20 cases comprising 10 OKC and 10 PA were included in retrospective study. Three paraffin section of 4 μm were cut, one was used for routine hematoxylin and eosin stain, while the other two were used for immunohistochemistry. Statistical analysis was performed using Chi-square test. The level of staining and intensity were assessed in all these cases. OKC showed PCNA expression in all cases (100%), whereas in perapical cyst only 60% of cases exhibited PCNA staining. (1) OKC showed p53 expression in 6 cases (60%) whereas in PA only 10% of the cases exhibited p53 staining. Chi-square test showed PCNA staining intensity was more significant than p53 in OKC. (2) The staining intensity of PA using p53, PCNA revealed that PCNA stating intensity was more significant than p53. OKC shows significant proliferative activity than PA using PCNA and p53. PCNA staining was more intense when compared with p53 in both OKC and PA.
Expression of p53, p21 and cyclin D1 in penile cancer: p53 predicts poor prognosis.

PubMed

Gunia, Sven; Kakies, Christoph; Erbersdobler, Andreas; Hakenberg, Oliver W; Koch, Stefan; May, Matthias

2012-03-01

To evaluate the role of p53, p21 and cyclin D1 expression in patients with penile cancer (PC). Paraffin-embedded tissues from PC specimens from six pathology departments were subjected to a central histopathological review performed by one pathologist. The tissue microarray technique was used for immunostaining which was evaluated by two independent pathologists and correlated with cancer-specific survival (CSS). κ-statistics were used to assess interobserver variability. Uni- and multivariable Cox proportional hazards analysis was applied to assess the independent effects of several prognostic factors on CSS over a median of 32 months (IQR 6-66 months). Specimens and clinical data from 110 men treated surgically for primary PC were collected. p53 staining was positive in 30 and negative in 62 specimens. κ-statistics showed substantial interobserver reproducibility of p53 staining evaluation (κ=0.73; p<0.001). The 5-year CSS rate for the entire study cohort was 74%. Five-year CSS was 84% in p53-negative and 51% in p53-positive PC patients (p=0.003). Multivariable analysis showed p53 (HR=3.20; p=0.041) and pT-stage (HR=4.29; p<0.001) as independent significant prognostic factors for CSS. Cyclin D1 and p21 expression were not correlated with survival. However, incorporating p21 into a multivariable Cox model did contribute to improved model quality for predicting CSS. In patients with PC, the expression of p53 in the primary tumour specimen can be reproducibly assessed and is negatively associated with cancer specific survival.
Perturbation of ribosome biogenesis drives cells into senescence through 5S RNP-mediated p53 activation.

PubMed

Nishimura, Kazuho; Kumazawa, Takuya; Kuroda, Takao; Katagiri, Naohiro; Tsuchiya, Mai; Goto, Natsuka; Furumai, Ryohei; Murayama, Akiko; Yanagisawa, Junn; Kimura, Keiji

2015-03-03

The 5S ribonucleoprotein particle (RNP) complex, consisting of RPL11, RPL5, and 5S rRNA, is implicated in p53 regulation under ribotoxic stress. Here, we show that the 5S RNP contributes to p53 activation and promotes cellular senescence in response to oncogenic or replicative stress. Oncogenic stress accelerates rRNA transcription and replicative stress delays rRNA processing, resulting in RPL11 and RPL5 accumulation in the ribosome-free fraction, where they bind MDM2. Experimental upregulation of rRNA transcription or downregulation of rRNA processing, mimicking the nucleolus under oncogenic or replicative stress, respectively, also induces RPL11-mediated p53 activation and cellular senescence. We demonstrate that exogenous expression of certain rRNA-processing factors rescues the processing defect, attenuates p53 accumulation, and increases replicative lifespan. To summarize, the nucleolar-5S RNP-p53 pathway functions as a senescence inducer in response to oncogenic and replicative stresses. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
Lung cancer incidence and survival in chromium exposed individuals with respect to expression of anti-apoptotic protein survivin and tumor suppressor P53 protein

PubMed Central

2010-01-01

Objective Workers chronically exposed to hexavalent chromium have elevated risk of lung cancer. Our study investigates the incidence of lung cancer types, age at onset of the disease, and survival time among chromium exposed workers with respect to the expression of anti-apoptotic p53 and pro-apoptotic survivin proteins. Materials and methods 67 chromium exposed workers and 104 male controls diagnosed with lung cancer were analyzed. The mean exposure time among workers was 16.7 ± 10.0(SD) years (range 1- 41 years). To investigate the possible regulation of survivin by p53 we examined the expression of both proteins using immohistochemical visualization. Results Chromium exposure significantly decreases the age of onset of the disease by 3.5 years (62.2 ± 9.1 in the exposed group vs. 65.7 ± 10.5 years in controls; P = 0.018). Small cell lung carcinoma (SCLC) amounted for 25.4% of all cases in chromium exposed workers and for 16.3% in non-exposed individuals. The mean survival time in the exposed group was 9.0 ± 12.7 vs. 12.1 ± 21.9 months in controls, but this difference was not significant. Survivin was predominantly expressed in both cell nucleus and cytoplasm, whereas p53 was expressed in the nucleus. There was a negative correlation between survivin and p53 expression. A decreased intensity of expression and fewer cells positive for survivin was detected in SCLC compared with other types of lung cancer. P53 was expressed in 94.1% and survivin in 79.6% of the samples analyzed. Conclusion The study calls attention to decreased expression of survivin, as opposed to p53, in small cell lung carcinoma. PMID:21147621
Multiple functions of p21 in cell cycle, apoptosis and transcriptional regulation after DNA damage.

PubMed

Karimian, Ansar; Ahmadi, Yasin; Yousefi, Bahman

2016-06-01

An appropriate control over cell cycle progression depends on many factors. Cyclin-dependent kinase (CDK) inhibitor p21 (also known as p21(WAF1/Cip1)) is one of these factors that promote cell cycle arrest in response to a variety of stimuli. The inhibitory effect of P21 on cell cycle progression correlates with its nuclear localization. P21 can be induced by both p53-dependent and p53-independent mechanisms. Some other important functions attributed to p21 include transcriptional regulation, modulation or inhibition of apoptosis. These functions are largely dependent on direct p21/protein interactions and also on p21 subcellular localizations. In addition, p21 can play a role in DNA repair by interacting with proliferating cell nuclear antigen (PCNA). In this review, we will focus on the multiple functions of p21 in cell cycle regulation, apoptosis and gene transcription after DNA damage and briefly discuss the pathways and factors that have critical roles in p21 expression and activity. Copyright © 2016 Elsevier B.V. All rights reserved.
CDC25B and p53 are independently implicated in radiation sensitivity for human esophageal cancers.

PubMed

Miyata, H; Doki, Y; Shiozaki, H; Inoue, M; Yano, M; Fujiwara, Y; Yamamoto, H; Nishioka, K; Kishi, K; Monden, M

2000-12-01

Ionized radiation leads to G1 arrest and apoptosis by a p53-dependent pathway and G2-M arrest through a p53-independent pathway. In this study, we evaluated the role of cell cycle-regulating molecules in the sensitivity of cancer cells for radiation therapy. Forty-seven patients with squamous cell carcinomas of the esophagus had undergone radiation therapy, followed by surgical resection. They were classified as sensitive to radiation (SR, 14 cases) with no residual tumor in the surgical specimen or as resistant to radiation (RR, 33 cases) with viable residual tumors. Their preradiation biopsy samples were immunohistochemically investigated for the expressions of cell cycle-related molecules, including p53, CDC25A, CDC25B, cyclin D1, cyclin B1, and Ki-67. p53 expression was negative in 71% (10 of 14) of SR and positive in 91% (30 of 33) of RR. The association was strong between high radiation sensitivity and negative p53 expression (P < 0.0001). CDC25B, which is not expressed in normal epithelium but is in the cytoplasm of esophageal cancers, was strongly expressed (2+) in 46% (6 of 14) of SR and in 6% (2 of 23) of RR. Thus, the sensitivity for radiation therapy was significantly correlated with CDC25B overexpression. With respect to CDC25A, cyclin D1, cyclin B1, and Ki-67, no statistically significant differences were found in their expressions between SR and RR tumors. p53 and CDC25B expressions showed no significant associations, and multivariate analysis revealed that both p53 and CDC25B are significant independent markers for predicting radiation sensitivity. CDC25B was revealed to be a novel predictor of radiation sensitivity in esophageal cancers. Because CDC25B is an oncogene, which affects G2-M progression, these results suggest the importance of a p53-independent G2-M checkpoint in radiation therapy.
Diagnostic value of progesterone receptor, p16, p53 and pHH3 expression in uterine atypical leiomyoma.

PubMed

Liang, Yun; Zhang, Xiaofei; Chen, Xiaoduan; Lü, Weiguo

2015-01-01

The differential diagnosis between atypical leiomyoma and leiomyosarcoma may be hard based on morphological criterion at times. It would be helpful to find out biomarkers that can be used to distinguish them. The aim of the study was to investigate the diagnostic value of progesterone receptor (PR), p16, p53 and pHH3 expression in a series of uterine smooth muscle tumors. Immunohistochemical expression of PR, p16, p53 and pHH3 was investigated on 32 atypical leiomyomas, 15 leiomyosarcomas and 15 usual leomyomas. The difference in expression was compared between atypical leiomyoma and other groups. The expression of PR, p16, and pHH3 was found significantly different between atypical leiomyomas and leiomyosarcomas, but lack of significant difference between atypical leiomyomas and usual leiomyomas. There was no significant difference with regard to p53 distribution among these uterine smooth muscle tumors. High p16, pHH3 expression and low PR expression preferred the diagnosis of leiomyosarcoma. The panel of antibodies used in this study is a useful complementary analysis in the assessment of problematic uterine smooth muscle tumors.
Diagnostic value of progesterone receptor, p16, p53 and pHH3 expression in uterine atypical leiomyoma

PubMed Central

Liang, Yun; Zhang, Xiaofei; Chen, Xiaoduan; Lü, Weiguo

2015-01-01

The differential diagnosis between atypical leiomyoma and leiomyosarcoma may be hard based on morphological criterion at times. It would be helpful to find out biomarkers that can be used to distinguish them. The aim of the study was to investigate the diagnostic value of progesterone receptor (PR), p16, p53 and pHH3 expression in a series of uterine smooth muscle tumors. Immunohistochemical expression of PR, p16, p53 and pHH3 was investigated on 32 atypical leiomyomas, 15 leiomyosarcomas and 15 usual leomyomas. The difference in expression was compared between atypical leiomyoma and other groups. The expression of PR, p16, and pHH3 was found significantly different between atypical leiomyomas and leiomyosarcomas, but lack of significant difference between atypical leiomyomas and usual leiomyomas. There was no significant difference with regard to p53 distribution among these uterine smooth muscle tumors. High p16, pHH3 expression and low PR expression preferred the diagnosis of leiomyosarcoma. The panel of antibodies used in this study is a useful complementary analysis in the assessment of problematic uterine smooth muscle tumors. PMID:26261614
Epigenetic identification of ZNF545 as a functional tumor suppressor in multiple myeloma via activation of p53 signaling pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Yu; Zhan, Qian; Xu, Hongying

The KRAB–zinc-finger protein ZNF545 was recently identified as a potential suppressor gene in several tumors. However, the regulatory mechanisms of ZNF545 in tumorigenesis remain unclear. In this study, we investigated the expression and roles of ZNF545 in multiple myeloma (MM). ZNF545 was frequently downregulated in MM tissues compared with non-tumor bone marrow tissues. ZNF545 expression was silenced by promoter methylation in MM cell lines, and could be restored by demethylation treatment. ZNF545 methylation was detected in 28.3% of MM tissues, compared with 4.3% of normal bone marrow tissues. ZNF545 transcriptionally activated the p53 signaling pathway but had no effect onmore » Akt in MM, whereas ectopic expression of ZNF545 in silenced cells suppressed their proliferation and induced apoptosis. We therefore identified ZNF545 as a novel tumor suppressor inhibiting tumor growth through activation of the p53 pathway in MM. Moreover, tumor-specific methylation of ZNF545 may represent an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. -- Highlights: •Downregulated ZNF545 in MM tissues and cell lines and ectopic expression of ZNF545 suppresses tumor growth. •Tumor-specific methylation of ZNF545 represents an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. •ZNF545 exerts its tumor suppressive effects via transcriptional activating p53 pathway.« less
Dynamic expression of the p53 family members p63 and p73 in the mouse and human telencephalon during development and in adulthood.

PubMed

Hernández-Acosta, N Carolina; Cabrera-Socorro, Alfredo; Morlans, Mercedes Pueyo; Delgado, Francisco J González; Suárez-Solá, M Luisa; Sottocornola, Roberta; Lu, Xin; González-Gómez, Miriam; Meyer, Gundela

2011-02-04

p63 and p73, family members of the tumor suppressor p53, are critically involved in the life and death of mammalian cells. They display high homology and may act in concert. The p73 gene is relevant for brain development, and p73-deficient mice display important malformations of the telencephalon. In turn, p63 is essential for the development of stratified epithelia and may also play a part in neuronal survival and aging. We show here that p63 and p73 are dynamically expressed in the embryonic and adult mouse and human telencephalon. During embryonic stages, Cajal-Retzius cells derived from the cortical hem co-express p73 and p63. Comparison of the brain phenotypes of p63- and p73- deficient mice shows that only the loss of p73 function leads to the loss of Cajal-Retzius cells, whereas p63 is apparently not essential for brain development and Cajal-Retzius cell formation. In postnatal mice, p53, p63, and p73 are present in cells of the subventricular zone (SVZ) of the lateral ventricle, a site of continued neurogenesis. The neurogenetic niche is reduced in size in p73-deficient mice, and the numbers of young neurons near the ventricular wall, marked with doublecortin, Tbr1 and calretinin, are dramatically decreased, suggesting that p73 is important for SVZ proliferation. In contrast to their restricted expression during brain development, p73 and p63 are widely detected in pyramidal neurons of the adult human cortex and hippocampus at protein and mRNA levels, pointing to a role of both genes in neuronal maintenance in adulthood. Copyright Â© 2010 Elsevier B.V. All rights reserved.
Efficient siRNA delivery system using carboxilated single-wall carbon nanotubes in cancer treatment.

PubMed

Neagoe, Ioana Berindan; Braicu, Cornelia; Matea, Cristian; Bele, Constantin; Florin, Graur; Gabriel, Katona; Veronica, Chedea; Irimie, Alexandru

2012-08-01

Several functionalized carbon nanotubes have been designed and tested for the purpose of nucleic acid delivery. In this study, the capacity of SWNTC-COOH for siRNA deliverey were investigated delivery in parallel with an efficient commercial system. Hep2G cells were reverse-transfected with 50 nM siRNA (p53 siRNA, TNF-alphasiRNA, VEGFsiRNA) using the siPORT NeoFX (Ambion) transfection agent in paralel with SWNTC-COOH, functionalised with siRNA. The highest level of gene inhibition was observed in the cases treated with p53 siRNA gene; in the case of transfection with siPort, the NeoFX value was 33.8%, while in the case of SWNTC-COOH as delivery system for p53 siRNA was 37.5%. The gene silencing capacity for VEGF was 53.7%, respectively for TNF-alpha 56.7% for siPORT NeoFX delivery systems versus 47.7% (VEGF) and 46.5% (TNF-alpha) for SWNTC-COOH delivery system. SWNTC-COOH we have been showed to have to be an efficient carrier system. The results from the inhibition of gene expresion for both transfection systems were confirmed at protein level. Overall, the lowest mRNA expression was confirmed at protein level, especially in the case of p53 siRNA and TNF-alpha siRNA transfection. Less efficient reduction protein expressions were observed in the case of VEGF siRNA, for both transfection systems at 24 h; only at 48 h, there was a statistically significant reduction of VEGF protein expression. SWCNT-COOH determined an efficient delivery of siRNA. SWNTC-COOH, combined with suitable tumor markers like p53 siRNA, TNFalpha siRNA or VEGF siRNA can be used for the efficient delivery of siRNA.
A common carcinogen benzo[a]pyrene causes p53 overexpression in mouse cervix via DNA damage.

PubMed

Gao, Meili; Li, Yongfei; Sun, Ying; Long, Jiangang; Kong, Yu; Yang, Shuiyun; Wang, Yili

2011-09-18

Benzo[a]pyrene (BaP) is cytotoxic and/or genotoxic to lung, stomach and skin tissue in the body. However, the effect of BaP on cervical tissue remains unclear. The present study detected DNA damage and the expression of the p53 gene in BaP-induced cervical tissue in female mice. Animals were intraperitoneally injected and orally gavaged with BaP at the doses of 2.5, 5, and 10mg/kg twice a week for 14 weeks. The single-cell gel electrophoresis (SCGE) assay was used to detect the DNA damage. Immunohistochemistry (IHC) and in situ hybridization (ISH) were used to detect the expression of p53 protein and p53 mRNA, respectively. The results showed that BaP induced a significant and dose-dependent increase of the number of cells with DNA damaged and the tail length as well as Comet tail moment in cervical tissue. The expression level of p53 protein and mRNA was increased. The results demonstrate that BaP may show toxic effect on the cervix by increasing DNA damage and the expression of the p53 gene. Copyright © 2011 Elsevier B.V. All rights reserved.

A high-throughput cellular assay to quantify the p53-degradation activity of E6 from different human papillomavirus types.

PubMed

Gagnon, David; Archambault, Jacques

2015-01-01

A subset of human papillomaviruses (HPVs), known as the high-risk types, are the causative agents of cervical cancer and other malignancies of the anogenital region and oral mucosa. The capacity of these viruses to induce cancer and to immortalize cells in culture relies in part on a critical function of their E6 oncoprotein, that of promoting the poly-ubiquitination of the cellular tumor suppressor protein p53 and its subsequent degradation by the proteasome. Here, we describe a cellular assay to measure the p53-degradation activity of E6 from different HPV types. This assay is based on a translational fusion of p53 to Renilla luciferase (Rluc-p53) that remains sensitive to degradation by high-risk E6 and whose steady-state levels can be accurately measured in standard luciferase assays. The p53-degradation activity of any E6 protein can be tested and quantified in transiently transfected cells by determining the amount of E6-expression vector required to reduce by half the levels of RLuc-p53 luciferase activity (50 % effective concentration [EC50]). The high-throughput and quantitative nature of this assay makes it particularly useful to compare the p53-degradation activities of E6 from several HPV types in parallel.
A p53-inducible microRNA-34a downregulates Ras signaling by targeting IMPDH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hwa-Ryeon; Roe, Jae-Seok; Lee, Ji-Eun

2012-02-24

Highlights: Black-Right-Pointing-Pointer p53 downregulates IMPDH. Black-Right-Pointing-Pointer p53-dependent miR-34a transactivation inhibits IMPDH transcription. Black-Right-Pointing-Pointer miR-34a-mediated inhibition of IMPDH downregulates GTP-dependent Ras signal. -- Abstract: p53 is a well-known transcription factor that controls cell cycle arrest and cell death in response to a wide range of stresses. Moreover, p53 regulates glucose metabolism and its mutation results in the metabolic switch to the Warburg effect found in cancer cells. Nucleotide biosynthesis is also critical for cell proliferation and the cell division cycle. Nonetheless, little is known about whether p53 regulates nucleotide biosynthesis. Here we demonstrated that p53-inducible microRNA-34a (miR-34a) repressed inosine 5 Primemore » -monophosphate dehydrogenase (IMPDH), a rate-limiting enzyme of de novo GTP biosynthesis. Treatment with anti-miR-34a inhibitor relieved the expression of IMPDH upon DNA damage. Ultimately, miR-34a-mediated inhibition of IMPDH resulted in repressed activation of the GTP-dependent Ras signaling pathway. In summary, we suggest that p53 has a novel function in regulating purine biosynthesis, aided by miR-34a-dependent IMPDH repression.« less
Concurrent acetylation of FoxO1/3a and p53 due to sirtuins inhibition elicit Bim/PUMA mediated mitochondrial dysfunction and apoptosis in berberine-treated HepG2 cells.

PubMed

Shukla, Shatrunajay; Sharma, Ankita; Pandey, Vivek Kumar; Raisuddin, Sheikh; Kakkar, Poonam

2016-01-15

Post-translational modifications i.e. phosphorylation and acetylation are pivotal requirements for proper functioning of eukaryotic proteins. The current study aimed to decode the impact of acetylation/deacetylation of non-histone targets i.e. FoxO1/3a and p53 of sirtuins (NAD(+) dependent enzymes with lysine deacetylase activity) in berberine treated human hepatoma cells. Berberine (100 μM) inhibited sirtuins significantly (P<0.05) at transcriptional level as well as at translational level. Combination of nicotinamide (sirtuin inhibitor) with berberine potentiated sirtuins inhibition and increased the expression of FoxO1/3a and phosphorylation of p53 tumor suppressor protein. As sirtuins deacetylate non-histone targets including FoxO1/3a and p53, berberine increased the acetylation load of FoxO1/3a and p53 proteins. Acetylated FoxO and p53 proteins transcriptionally activate BH3-only proteins Bim and PUMA (3.89 and 3.87 fold respectively, P<0.001), which are known as direct activator of pro-apoptotic Bcl-2 family protein Bax that culminated into mitochondria mediated activation of apoptotic cascade. Bim/PUMA knock-down showed no changes in sirtuins' expression while cytotoxicity induced by berberine and nicotinamide was curtailed up to 28.3% (P<0.001) and it restored pro/anti apoptotic protein ratio in HepG2 cells. Sirtuins inhibition was accompanied by decline in NAD(+)/NADH ratio, ATP generation, enhanced ROS production and decreased mitochondrial membrane potential. TEM analysis confirmed mitochondrial deterioration and cell damage. SRT-1720 (1-10 μM), a SIRT-1 activator, when pre-treated with berberine (25 μM), reversed sirtuins expression comparable to control and significantly restored the cell viability (P<0.05). Thus, our findings suggest that berberine mediated sirtuins inhibition resulting into FoxO1/3a and p53 acetylation followed by BH3-only protein Bim/PUMA activation may in part be responsible for mitochondria-mediated apoptosis. Copyright © 2015 Elsevier Inc. All rights reserved.
p53 AND MDM2 PROTEIN EXPRESSION IN ACTINIC CHEILITIS

PubMed Central

de Freitas, Maria da Conceição Andrade; Ramalho, Luciana Maria Pedreira; Xavier, Flávia Caló Aquino; Moreira, André Luis Gomes; Reis, Sílvia Regina Almeida

2008-01-01

Actinic cheilitis is a potentially malignant lip lesion caused by excessive and prolonged exposure to ultraviolet radiation, which can lead to histomorphological alterations indicative of abnormal cell differentiation. In this pathology, varying degrees of epithelial dysplasia may be found. There are few published studies regarding the p53 and MDM2 proteins in actinic cheilitis. Fifty-eight cases diagnosed with actinic cheilitis were histologically evaluated using Banóczy and Csiba (1976) parameters, and were subjected to immunohistochemical analysis using the streptavidin-biotin method in order to assess p53 and MDM2 protein expression. All studied cases expressed p53 proteins in basal and suprabasal layers. In the basal layer, the nuclei testing positive for p53 were stained intensely, while in the suprabasal layer, cells with slightly stained nuclei were predominant. All cases also tested positive for the MDM2 protein, but with varying degrees of nuclear expression and a predominance of slightly stained cells. A statistically significant correlation between the percentage of p53 and MDM2-positive cells was established, regardless of the degree of epithelial dysplasia. The expression of p53 and MDM2 proteins in actinic cheilitis can be an important indicator in lip carcinogenesis, regardless of the degree of epithelial dysplasia. PMID:19082401
p53 and MDM2 protein expression in actinic cheilitis.

PubMed

de Freitas, Maria da Conceição Andrade; Ramalho, Luciana Maria Pedreira; Xavier, Flávia Caló Aquino; Moreira, André Luis Gomes; Reis, Sílvia Regina Almeida

2008-01-01

Actinic cheilitis is a potentially malignant lip lesion caused by excessive and prolonged exposure to ultraviolet radiation, which can lead to histomorphological alterations indicative of abnormal cell differentiation. In this pathology, varying degrees of epithelial dysplasia may be found. There are few published studies regarding the p53 and MDM2 proteins in actinic cheilitis. Fifty-eight cases diagnosed with actinic cheilitis were histologically evaluated using Banóczy and Csiba (1976) parameters, and were subjected to immunohistochemical analysis using the streptavidin-biotin method in order to assess p53 and MDM2 protein expression. All studied cases expressed p53 proteins in basal and suprabasal layers. In the basal layer, the nuclei testing positive for p53 were stained intensely, while in the suprabasal layer, cells with slightly stained nuclei were predominant. All cases also tested positive for the MDM2 protein, but with varying degrees of nuclear expression and a predominance of slightly stained cells. A statistically significant correlation between the percentage of p53 and MDM2-positive cells was established, regardless of the degree of epithelial dysplasia. The expression of p53 and MDM2 proteins in actinic cheilitis can be an important indicator in lip carcinogenesis, regardless of the degree of epithelial dysplasia.
Promotive Effect of Minoxidil Combined with All-trans Retinoic Acid (tretinoin) on Human Hair Growth in Vitro

PubMed Central

Kwon, Oh Sang; Pyo, Hyun Keol; Oh, Youn Jin; Han, Ji Hyun; Lee, Se Rah; Chung, Jin Ho; Eun, Hee Chul

2007-01-01

Minoxidil induces hair growth in male pattern baldness and prolongs the anagen phase. All-trans retinoic acid (ATRA) has been reported to act synergistically with minoxidil in vivo: they can enhance more dense hair regrowth than either compound alone. We evaluated the effect of minoxidil combined with ATRA on hair growth in vitro. The effect of co-treatment of minoxidil and ATRA on hair growth was studied in hair follicle organ culture. In cultured human dermal papilla cells (DPCs) and normal human epidermal keratinocytes, the expressions of Erk, Akt, Bcl-2, Bax, P53 and P21 were evaluated by immunoblot analysis. Minoxidil plus ATRA additively promoted hair growth in vitro, compared with minoxidil alone. In addition, minoxidil plus ATRA elevated phosphorylated Erk, phosphorylated Akt and the ratio of Bcl-2/Bax, but decreased the expressions of P53 and P21 more effectively than by minoxidil alone. Our results suggest that minoxidil plus ATRA would additively enhance hair growth by mediating dual functions: 1) the prolongation of cell survival by activating the Erk and Akt signaling pathways, and 2) the prevention of apoptosis of DPCs and epithelial cells by increasing the ratio of Bcl-2/Bax and downregulating the expressions of P53 and P21. PMID:17449938
Antiproliferative and Apoptotic Effect of Dendrosomal Curcumin Nanoformulation in P53 Mutant and Wide-Type Cancer Cell Lines.

PubMed

Montazeri, Maryam; Pilehvar-Soltanahmadi, Younes; Mohaghegh, Mina; Panahi, Alireza; Khodi, Samaneh; Zarghami, Nosratollah; Sadeghizadeh, Majid

2017-01-01

The aim of this paper is to investigate the effect of dendrosomal curcumin (DNC) on the expression of p53 in both p53 mutant cell lines SKBR3/SW480 and p53 wild-type MCF7/HCT116 in both RNA and protein levels. Curcumin, derived from Curcumin longa, is recently considered in cancer related researches for its cell growth inhibition properties. p53 is a common tumor-suppressor gene involved in cancers and its mutation not only inhibits tumor suppressor activity but also promotes oncogenic activity. Here, p53 mutant/Wild-type cells were employed to study the toxicity of DNC using MTT assay, Flow cytometry and Annexin-V, Real-time PCR and Western blot were used to analyze p53, BAX, Bcl-2, p21 and Noxa changes after treatment. During the time, DNC increased the SubG1 cells and decreased G1, S and G2/M cells, early apoptosis also indicated the inhibition of cell growth in early phase. Real-Time PCR assay showed an increased mRNA of BAX, Noxa and p21 during the time with decreased Bcl-2. The expression of p53 mutant decreased in SKBR3/SW480, and the expression of p53 wild-type increased in MCF7/HCT116. Consequently, p53 plays an important role in mediating the survival by DNC, which can prevent tumor cell growth by modulating the expression of genes involved in apoptosis and proliferation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
Low dose arsenite confers resistance to UV induced apoptosis via p53-MDM2 pathway in ketatinocytes

PubMed Central

Zhou, Y; Zeng, W; Qi, M; Duan, Y; Su, J; Zhao, S; Zhong, W; Gao, M; Li, F; He, Y; Hu, X; Xu, X; Chen, X; Peng, C; Zhang, J

2017-01-01

Chronic arsenite and ultraviolet (UV) exposure are associated with skin tumor. To investigate the details by low concentrations of arsenite and UV induced carcinogenesis in skin, hTERT-immortalized human keratinocytes were used as a cellular model with exposure to low concentrations of sodium arsenite and UV. The effect of NaAsO2 on UV treatment-induced apoptosis was measured by flow cytometry and Hoechst staining. We found that the cell apoptosis induced by UV exposure was significantly attenuated after exposure to low-dose arsenite, and knockdown of p53 could block UV-induced apoptosis indicating that this phenomenon depended on p53. Interestingly, the expression of murine double minute 2 (MDM2), including its protein and transcriptional levels, was remarkably high after exposure to low-dose arsenite. Moreover, low-dose arsenite treatment dramatically decreased the MDM2 gene promoter activity, suggesting that this effect has been mediated through transcription. In addition, treatment of PD98059 reversed low-dose arsenite-induced MDM2 expression, and the inhibition of ERK2 expression could significantly block MDM2 expression as a consequence, and p53 expression automatically was increased. To validate the role of p53 in exposure to low-dose arsenite, the expression of p53 was examined by immunohistochemistry in the skin of Sprague−Dawley rats model by chronic arsenite exposure for 6 months and in patients with arsenic keratosis, and the results showed that the expression of p53 was decreased in those samples. Taken together, our results demonstrated that low-dose arsenite-induced resistance to apoptosis through p53 mediated by MDM2 in keratinocytes. PMID:28785074
Integration of Genomic, Biologic, and Chemical Approaches to Target p53 Loss and Gain-of-Function in Triple Negative Breast Cancer

DTIC Science & Technology

2014-09-01

in this renewal: p53 triple negative breast cancer subtypes gene expression somatic cell genetics CRISPR /Cas 3. OVERALL PROJECT SUMMARY...to the efficacy of the synthetic lethality screen. In addition, we have optimized the use of CRISPR /Cas, a novel somatic cell recombination...completing this stage of the research within the upcoming Year 2 of the award period. Figure 1. CRISPR /Cas-mediated in vitro somatic cell
P53 Mutation Analysis to Predict Tumor Response in Patients Undergoing Neoadjuvant Treatment for Locally Advanced Breast Cancer

DTIC Science & Technology

2006-10-01

then sequenced (for GeneChip- positiv SSCP (for GeneChip-negative). We have received a total of 43 core breast biopsy DNA samples from the UNC... quantitative luciferase reporter. Both reporters exploit a “rheostatable” promoter for p53 expression and utilize the “delitto perfetto” in vivo... quantitative luciferase-based assay is also being used to characterize the altered function sistent an tion T mutants in greater detail. Preliminary
Effects of p53 on aldosterone-induced mesangial cell apoptosis in vivo and in vitro.

PubMed

Shi, Huimin; Zhang, Aiqing; He, Yanfang; Yang, Min; Gan, Weihua

2016-06-01

Aldosterone (ALD) is a well‑known hormone, which may initiate renal injury by inducing mesangial cell (MC) injury in chronic kidney disease (CKD); however, the molecular mechanism remains unknown. The aim of the present study was to investigate the effects of p53 on ALD‑induced MC apoptosis and elucidate the underlying molecular mechanism. For the in vivo studies, rats were randomly assigned to receive normal saline or ALD for 4 weeks. The ratio of MC apoptosis was analysed by terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay. In addition, the expression level and localisation of p53, a well-known cell apoptosis-associated key protein, were detected by immunofluorescence. For the in vitro studies, rat MCs were incubated in medium containing either buffer (control) or ALD (10‑6 M) for 24 h. The cell apoptosis ratio was assessed by flow cytometry, and the expression level of p53 was assessed by reverse transcription quantitative polymerase chain reaction and western blotting. In order to confirm the role of p53 in ALD‑regulated cell apoptosis, a rescue experiment was performed using targeted small interfering (si)RNA to downregulate the expression of p53. The ALD‑treated rats exhibited greater numbers of TUNEL‑positive MCs and higher expression levels of p53 when compared with the control group. Furthermore, the ratio of MC apoptosis and the p53 expression level were significantly increased following ALD exposure, compared with the control group. Additionally, in the rescue experiment, the effects of ALD on MC were blocked by downregulating the expression level of p53 in MCs. The present study hypothesized that ALD may directly contribute to the occurrence of MC apoptosis via p53, which may participate in ALD-induced renal injury.
Concordant p53 and mdm-2 protein expression in vulvar squamous cell carcinoma and adjacent lichen sclerosus.

PubMed

Carlson, J A; Amin, S; Malfetano, J; Tien, A T; Selkin, B; Hou, J; Goncharuk, V; Wilson, V L; Rohwedder, A; Ambros, R; Ross, J S

2001-06-01

To determine if carcinogenic events in vulvar skin precede the onset of morphologic atypia, the authors investigated for derangements in DNA content, cell proliferation, and cell death in vulvar carcinomas and surrounding skin in 140 samples of tumor and surrounding skin collected from 35 consecutive vulvectomy specimen for squamous cell carcinoma (SCC) or vulvar intraepithelial neoplasia (VIN) 3. Vulvar non-cancer excisions were used as controls. Investigations consisted of histologic classification and measurement of 9 variables--epidermal thickness (acanthosis and rete ridge length), immunolabeling index (LI) for 3 proteins (p53 protein, Ki-67, and mdm-2), pattern of p53 expression (dispersed vs. compact), DNA content index, and presence of aneuploidy by image analysis and apoptotic rate by Apotag labeling. Significant positive correlations were found for all nine variables studied versus increasing histologic severity in two proposed histologic stepwise models of vulvar carcinogenesis (lichen sclerosus (LS) and VIN 3 undifferentiated associated SCC groups). High p53 LI (>25) and the compact pattern of p53 expression (suspected oncoprotein) significantly correlated with LS and its associated vulvar samples compared with samples not associated with LS (P < or = 0.001). Furthermore, p53 LI, mdm-2 LI, and pattern of p53 expression were concordant between patient matched samples of LS and SCC. In addition, mdm-2 LI significantly correlated with dispersed pattern p53 LI suggesting a response to wild-type p53 protein accumulation. These findings support the hypothesis that neoplastic transformation occurs in sequential steps and compromises proteins involved in the cell cycle control. Concordance of p53 and mdm-2 protein expression in LS and adjacent SCC provides evidence that LS can act as a precursor lesion in the absence of morphologic atypia. Overexpression of mdm-2 with stabilization and inactivation of p53 protein may provide an alternate pathway for vulvar carcinogenesis.
Dihydroptychantol A, a macrocyclic bisbibenzyl derivative, induces autophagy and following apoptosis associated with p53 pathway in human osteosarcoma U2OS cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Xia; School of Ocean, Shandong University, Weihai 264209; Wu, William K.K.

2011-03-01

Dihydroptychantol A (DHA), a novel macrocyclic bisbibenzyl compound extracted from liverwort Asterella angusta, has antifungal and multi-drug resistance reversal properties. Here, the chemically synthesized DHA was employed to test its anti-cancer activities in human osteosarcoma U2OS cells. Our results demonstrated that DHA induced autophagy followed by apoptotic cell death accompanied with G{sub 2}/M-phase cell cycle arrest in U2OS cells. DHA-induced autophagy was morphologically characterized by the formation of double membrane-bound autophagic vacuoles recognizable at the ultrastructural level. DHA also increased the levels of LC3-II, a marker of autophagy. Surprisingly, DHA-mediated apoptotic cell death was potentiated by the autophagy inhibitor 3-methyladenine,more » suggesting that autophagy may play a protective role that impedes the eventual cell death. Furthermore, p53 was shown to be involved in DHA-meditated autophagy and apoptosis. In this connection, DHA increased nuclear expression of p53, induced p53 phosphorylation, and upregulated p53 target gene p21{sup Waf1/Cip1}. In contrast, cytoplasmic p53 was reduced by DHA, which contributed to the stimulation of autophagy. In relation to the cell cycle, DHA decreased the expression of cyclin B{sub 1}, a cyclin required for progression through the G{sub 2}/M phase. Taken together, DHA induces G{sub 2}/M-phase cell cycle arrest and apoptosis in U2OS cells. DHA-induced apoptosis was preceded by the induction of protective autophagy. DHA-mediated autophagy and apoptosis are associated with the cytoplasmic and nuclear functions of p53.« less
Heterozygous inactivation of tsc2 enhances tumorigenesis in p53 mutant zebrafish

PubMed Central

Kim, Seok-Hyung; Kowalski, Marie L.; Carson, Robert P.; Bridges, L. Richard; Ess, Kevin C.

2013-01-01

SUMMARY Tuberous sclerosis complex (TSC) is a multi-organ disorder caused by mutations of the TSC1 or TSC2 genes. A key function of these genes is to inhibit mTORC1 (mechanistic target of rapamycin complex 1) kinase signaling. Cells deficient for TSC1 or TSC2 have increased mTORC1 signaling and give rise to benign tumors, although, as a rule, true malignancies are rarely seen. In contrast, other disorders with increased mTOR signaling typically have overt malignancies. A better understanding of genetic mechanisms that govern the transformation of benign cells to malignant ones is crucial to understand cancer pathogenesis. We generated a zebrafish model of TSC and cancer progression by placing a heterozygous mutation of the tsc2 gene in a p53 mutant background. Unlike tsc2 heterozygous mutant zebrafish, which never exhibited cancers, compound tsc2;p53 mutants had malignant tumors in multiple organs. Tumorigenesis was enhanced compared with p53 mutant zebrafish. p53 mutants also had increased mTORC1 signaling that was further enhanced in tsc2;p53 compound mutants. We found increased expression of Hif1-α, Hif2-α and Vegf-c in tsc2;p53 compound mutant zebrafish compared with p53 mutant zebrafish. Expression of these proteins probably underlies the increased angiogenesis seen in compound mutant zebrafish compared with p53 mutants and might further drive cancer progression. Treatment of p53 and compound mutant zebrafish with the mTORC1 inhibitor rapamycin caused rapid shrinkage of tumor size and decreased caliber of tumor-associated blood vessels. This is the first report using an animal model to show interactions between tsc2, mTORC1 and p53 during tumorigenesis. These results might explain why individuals with TSC rarely have malignant tumors, but also suggest that cancer arising in individuals without TSC might be influenced by the status of TSC1 and/or TSC2 mutations and be potentially treatable with mTORC1 inhibitors. PMID:23580196
Mutant p53-Expressing Cells Undergo Necroptosis via Cell Competition with the Neighboring Normal Epithelial Cells.

PubMed

Watanabe, Hirotaka; Ishibashi, Kojiro; Mano, Hiroki; Kitamoto, Sho; Sato, Nanami; Hoshiba, Kazuya; Kato, Mugihiko; Matsuzawa, Fumihiko; Takeuchi, Yasuto; Shirai, Takanobu; Ishikawa, Susumu; Morioka, Yuka; Imagawa, Toshiaki; Sakaguchi, Kazuyasu; Yonezawa, Suguru; Kon, Shunsuke; Fujita, Yasuyuki

2018-06-26

p53 is a tumor suppressor protein, and its missense mutations are frequently found in human cancers. During the multi-step progression of cancer, p53 mutations generally accumulate at the mid or late stage, but not in the early stage, and the underlying mechanism is still unclear. In this study, using mammalian cell culture and mouse ex vivo systems, we demonstrate that when p53R273H- or p53R175H-expressing cells are surrounded by normal epithelial cells, mutant p53 cells undergo necroptosis and are basally extruded from the epithelial monolayer. When mutant p53 cells alone are present, cell death does not occur, indicating that necroptosis results from cell competition with the surrounding normal cells. Furthermore, when p53R273H mutation occurs within RasV12-transformed epithelia, cell death is strongly suppressed and most of the p53R273H-expressing cells remain intact. These results suggest that the order of oncogenic mutations in cancer development could be dictated by cell competition. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
Both germ line and somatic genetics of the p53 pathway affect ovarian cancer incidence and survival.

PubMed

Bartel, Frank; Jung, Juliane; Böhnke, Anja; Gradhand, Elise; Zeng, Katharina; Thomssen, Christoph; Hauptmann, Steffen

2008-01-01

Although p53 is one of the most studied genes/proteins in ovarian carcinomas, the predictive value of p53 alterations is still ambiguous. We performed analyses of the TP53 mutational status and its protein expression using immunohistochemistry. Moreover, the single nucleotide polymorphism SNP309 in the P2 promoter of the MDM2 gene was investigated. We correlated the results with age of onset and outcome from 107 patients with ovarian carcinoma. In our study, we identified a large group of patients with p53 overexpression despite having a wild-type gene (49% of all patients with wild-type TP53). This was associated with a significantly shortened overall survival time (P = 0.019). Patients with p53 alterations (especially those with overexpression of wild-type TP53) were also more refractory to chemotherapy compared with patients with normal p53 (P = 0.027). The G-allele of SNP309 is associated with an earlier age of onset in patients with estrogen receptor-overexpressing FIGO stage III disease (P = 0.048). In contrast, in patients with FIGO stage III disease, a weakened p53 pathway (either the G-allele of SNP309 or a TP53 mutation) was correlated with increased overall survival compared with patients whose tumors were wild-type for both TP53 and SNP309 (P = 0.0035). Our study provides evidence that both germ line and somatic alterations of the p53 pathway influence the incidence and survival of ovarian carcinoma, and it underscores the importance of assessing the functionality of p53 in order to predict the sensitivity of platinum-based chemotherapies and patient outcome.
Regulation of p53 Target Gene Expression by Peptidylarginine Deiminase 4 ▿ †

PubMed Central

Li, Pingxin; Yao, Hongjie; Zhang, Zhiqiang; Li, Ming; Luo, Yuan; Thompson, Paul R.; Gilmour, David S.; Wang, Yanming

2008-01-01

Histone Arg methylation has been correlated with transcriptional activation of p53 target genes. However, whether this modification is reversed to repress the expression of p53 target genes is unclear. Here, we report that peptidylarginine deiminase 4, a histone citrullination enzyme, is involved in the repression of p53 target genes. Inhibition or depletion of PAD4 elevated the expression of a subset of p53 target genes, including p21/CIP1/WAF1, leading to cell cycle arrest and apoptosis. Moreover, the induction of p21, cell cycle arrest, and apoptosis by PAD4 depletion is p53 dependent. Protein-protein interaction studies showed an interaction between p53 and PAD4. Chromatin immunoprecipitation assays showed that PAD4 is recruited to the p21 promoter in a p53-dependent manner. RNA polymerase II (Pol II) activities and the association of PAD4 are dynamically regulated at the p21 promoter during UV irradiation. Paused RNA Pol II and high levels of PAD4 were detected before UV treatment. At early time points after UV treatment, an increase of histone Arg methylation and a decrease of citrullination were correlated with a transient activation of p21. At later times after UV irradiation, a loss of RNA Pol II and an increase of PAD4 were detected at the p21 promoter. The dynamics of RNA Pol II activities after UV treatment were further corroborated by permanganate footprinting. Together, these results suggest a role of PAD4 in the regulation of p53 target gene expression. PMID:18505818
Heterogeneity of p53 dependent genomic responses following ethanol exposure in a developmental mouse model of fetal alcohol spectrum disorder.

PubMed

Camargo Moreno, Maria; Mooney, Sandra M; Middleton, Frank A

2017-01-01

Prenatal ethanol exposure can produce structural and functional deficits in the brain and result in Fetal Alcohol Spectrum Disorder (FASD). In rodent models acute exposure to a high concentration of alcohol causes increased apoptosis in the developing brain. A single causal molecular switch that signals for this increase in apoptosis has yet to be identified. The protein p53 has been suggested to play a pivotal role in enabling cells to engage in pro-apoptotic processes, and thus figures prominently as a hub molecule in the intracellular cascade of responses elicited by alcohol exposure. In the present study we examined the effect of ethanol-induced cellular and molecular responses in primary somatosensory cortex (SI) and hippocampus of 7-day-old wild-type (WT) and p53-knockout (KO) mice. We quantified apoptosis by active caspase-3 immunohistochemistry and ApopTag™ labeling, then determined total RNA expression levels in laminae of SI and hippocampal subregions. Immunohistochemical results confirmed increased incidence of apoptotic cells in both regions in WT and KO mice following ethanol exposure. The lack of p53 was not protective in these brain regions. Molecular analyses revealed a heterogeneous response to ethanol exposure that varied depending on the subregion, and which may go undetected using a global approach. Gene network analyses suggest that the presence or absence of p53 alters neuronal function and synaptic modifications following ethanol exposure, in addition to playing a classic role in cell cycle signaling. Thus, p53 may function in a way that underlies the intellectual and behavioral deficits observed in FASD.
Survivin safeguards chromosome numbers and protects from aneuploidy independently from p53

PubMed Central

2014-01-01

Background Survivin, a member of the inhibitor of apoptosis (IAP) gene family, has a dual role in mitosis and in apoptosis. It is abundantly expressed in every human tumor, compared with normal tissues. During mitosis Survivin assembles with the chromosomal passenger complex and regulates chromosomal segregation. Here, we aim to explore whether interference with the mitotic function of Survivin is linked to p53-mediated G1 cell cycle arrest and affects chromosomal stability. Methods In this study, we used HCT116, SBC-2, and U87-MG and generated corresponding isogenic p53-deficient cells. Retroviral vectors were used to stably knockdown Survivin. The resulting phenotype, in particular the mechanisms of cell cycle arrest and of initiation of aneuploidy, were investigated by Western Blot analysis, confocal laser scan microscopy, proliferation assays, spectral karyotyping and RNAi. Results In all cell lines Survivin-RNAi did not induce instant apoptosis but caused polyplodization irrespective of p53 status. Strikingly, polyploidization after knockdown of Survivin resulted in merotelic kinetochore spindle assemblies, γH2AX-foci, and DNA damage response (DDR), which was accompanied by a transient p53-mediated G1-arrest. That p53 wild type cells specifically arrest due to DNA damage was shown by simultaneous inhibition of ATM and DNA-PK, which abolished induction of p21waf/cip. Cytogenetic analysis revealed chromosomal aberrations indicative for DNA double strand break repair by the mechanism of non-homologous end joining (NHEJ), only in Survivin-depleted cells. Conclusion Our findings suggest that Survivin plays an essential role in proper amphitelic kinetochore-spindle assembly and that constraining Survivin’s mitotic function results in polyploidy and aneuploidy which cannot be controlled by p53. Therefore, Survivin critically safeguards chromosomal stability independently from p53. PMID:24886358
Human rpL3 induces G₁/S arrest or apoptosis by modulating p21waf1/cip1 levels in a p53-independent manner

PubMed Central

Russo, Annapina; Esposito, Davide; Catillo, Morena; Pietropaolo, Concetta; Crescenzi, Elvira; Russo, Giulia

2013-01-01

It is now largely accepted that ribosomal proteins may be implicated in a variety of biological functions besides that of components of the translation machinery. Many evidences show that a subset of ribosomal proteins are involved in the regulation of the cell cycle and apoptosis through modulation of p53 activity. In addition, p53-independent mechanisms of cell cycle arrest in response to alterations of ribosomal proteins availability have been described. Here, we identify human rpL3 as a new regulator of cell cycle and apoptosis through positive regulation of p21 expression in a p53-independent system. We demonstrate that the rpL3-mediated p21 upregulation requires the specific interaction between rpL3 and Sp1. Furthermore, in our experimental system, p21 overexpression leads to a dual outcome, activating the G₁/S arrest of the cell cycle or the apoptotic pathway through mitochondria, depending on its intracellular levels. It is noteworthy that depletion of p21 abrogates both effects. Taken together, our findings unravel a novel extraribosomal function of rpL3 and reinforce the proapoptotic role of p21 in addition to its widely reported ability as an inhibitor of cell proliferation. PMID:23255119

Identification of Akt Interaction Protein PHF20/TZP That Transcriptionally Regulates p53*

PubMed Central

Park, Sungman; Kim, Donghwa; Dan, Han C.; Chen, Huihua; Testa, Joseph R.; Cheng, Jin Q.

2012-01-01

Akt regulates a diverse array of cellular functions, including cell survival, proliferation, differentiation, and metabolism. Although a number of molecules have been identified as upstream regulators and downstream targets of Akt, the mechanisms by which Akt regulates these cellular processes remain elusive. Here, we demonstrate that a novel transcription factor, PHF20/TZP (referring to Tudor and zinc finger domain containing protein), binds to Akt and induces p53 expression at the transcription level. Knockdown of PHF20 significantly reduces p53. PHF20 inhibits cell growth, DNA synthesis, and cell survival. Akt phosphorylates PHF20 at Ser291 in vitro and in vivo, which results in its translocation from the nucleus to the cytoplasm and attenuation of PHF20 function. These data indicate that PHF20 is a substrate of Akt and plays a role in Akt cell survival/growth signaling. PMID:22334668
MicroRNA-520g Confers Drug Resistance by Regulating p21 Expression in Colorectal Cancer*

PubMed Central

Zhang, Yang; Geng, Liying; Talmon, Geoffrey; Wang, Jing

2015-01-01

Development of drug resistance is one of the major causes of colorectal cancer recurrence, yet mechanistic understanding and therapeutic options remain limited. Here, we show that expression of microRNA (miR)-520g is correlated with drug resistance of colon cancer cells. Ectopic expression of miR-520g conferred resistance to 5-fluorouracil (5-FU)- or oxaliplatin-induced apoptosis in vitro and reduced the effectiveness of 5-FU in the inhibition of tumor growth in a mouse xenograft model in vivo. Further studies indicated that miR-520g mediated drug resistance through down-regulation of p21 expression. Moreover, p53 suppressed miR-520g expression, and deletion of p53 up-regulated miR-520g expression. Inhibition of miR-520g in p53−/− cells increased their sensitivity to 5-FU treatment. Importantly, studies of patient samples indicated that expression of miR-520g correlated with chemoresistance in colorectal cancer. These findings indicate that the p53/miR-520g/p21 signaling axis plays an important role in the response of colorectal cancer to chemotherapy. A major implication of our studies is that inhibition of miR-520g or restoration of p21 expression may have considerable therapeutic potential to overcome drug resistance in colorectal cancer patients, especially in those with mutant p53. PMID:25616665
The PTTG1-targeting miRNAs miR-329, miR-300, miR-381, and miR-655 inhibit pituitary tumor cell tumorigenesis and are involved in a p53/PTTG1 regulation feedback loop

PubMed Central

Diao, Cai-feng; Li, Jian-wei; Su, Jing-liang; Zhang, Sai

2015-01-01

Deregulation of the pituitary tumor transforming gene (PTTG1), a newly discovered oncogene, is a hallmark of various malignancies, including pituitary tumors. However, the mechanisms regulating PTTG1 expression are still needed to be explored. MicroRNAs (miRNAs) are a novel class of small RNA molecules that act as posttranscriptional regulators of gene expression and can play a significant role in tumor development. Here, we identified a series of miRNAs, namely, miR-329, miR-300, miR-381 and miR-655, which could target PTTG1 messenger RNA and inhibit its expression. Interestingly, all four miRNAs significantly that are downregulated in pituitary tumors were mapped to the 14q32.31 locus, which acts as a tumor suppressor in several cancers. Functional studies show that the PTTG1-targeting miRNAs inhibit proliferation, migration and invasion but induce apoptosis in GH3 and MMQ cells. Furthermore, overexpression of a PTTG1 expression vector lacking the 3′UTR partially reverses the tumor suppressive effects of these miRNAs. Next, we identified the promoter region of PTTG1-targeting miRNAs with binding sites for p53. In our hands, p53 transcriptionally activated the expression of these miRNAs in pituitary tumor cells. Finally, we found that PTTG1 could inhibit p53 transcriptional activity to the four miRNAs. These data indicate the existence of a feedback loop between PTTG1 targeting miRNAs, PTTG1 and p53 that promotes pituitary tumorigenesis. Together, these findings suggest that these PTTG1-targeting miRNAs are important players in the regulation of pituitary tumorigenesis and that these miRNAs may serve as valuable therapeutic targets for cancer treatment. PMID:26320179
Dehydroandrographolide, an iNOS inhibitor, extracted from Andrographis paniculata (Burm.f.) Nees, induces autophagy in human oral cancer cells.

PubMed

Hsieh, Ming-Ju; Lin, Chiao-Wen; Chiou, Hui-Ling; Yang, Shun-Fa; Chen, Mu-Kuan

2015-10-13

Autophagy, which is constitutively executed at the basal level in all cells, promotes cellular homeostasis by regulating the turnover of organelles and proteins. Andrographolide and dehydroandrographolide (DA) are the two principle components of Andrographis paniculata (Burm.f.) Nees. and are the main contributors to its therapeutic properties. However, the pharmacological activities of dehydroandrographolide (DA) remain unclear. In this study, DA induces oral cancer cell death by activating autophagy. Treatment with autophagy inhibitors inhibited DA-induced human oral cancer cell death. In addition, DA increased LC3-II expression and reduced p53 expression in a time- and concentration-dependent manner. Furthermore, DA induced autophagy and decreased cell viability through modulation of p53 expression. DA-induced autophagy was triggered by an activation of JNK1/2 and an inhibition of Akt and p38. In conclusion, this study demonstrated that DA induced autophagy in human oral cancer cells by modulating p53 expression, activating JNK1/2, and inhibiting Akt and p38. Finally, an administration of DA effectively suppressed the tumor formation in the oral carcinoma xenograft model in vivo. This is the first study to reveal the novel function of DA in activating autophagy, suggesting that DA could serve as a new and potential chemopreventive agent for treating human oral cancer.
Dehydroandrographolide, an iNOS inhibitor, extracted from from Andrographis paniculata (Burm.f.) Nees, induces autophagy in human oral cancer cells

PubMed Central

Hsieh, Ming-Ju; Lin, Chiao-Wen; Chiou, Hui-Ling; Yang, Shun-Fa; Chen, Mu-Kuan

2015-01-01

Autophagy, which is constitutively executed at the basal level in all cells, promotes cellular homeostasis by regulating the turnover of organelles and proteins. Andrographolide and dehydroandrographolide (DA) are the two principle components of Andrographis paniculata (Burm.f.) Nees. and are the main contributors to its therapeutic properties. However, the pharmacological activities of dehydroandrographolide (DA) remain unclear. In this study, DA induces oral cancer cell death by activating autophagy. Treatment with autophagy inhibitors inhibited DA-induced human oral cancer cell death. In addition, DA increased LC3-II expression and reduced p53 expression in a time- and concentration-dependent manner. Furthermore, DA induced autophagy and decreased cell viability through modulation of p53 expression. DA-induced autophagy was triggered by an activation of JNK1/2 and an inhibition of Akt and p38. In conclusion, this study demonstrated that DA induced autophagy in human oral cancer cells by modulating p53 expression, activating JNK1/2, and inhibiting Akt and p38. Finally, an administration of DA effectively suppressed the tumor formation in the oral carcinoma xenograft model in vivo. This is the first study to reveal the novel function of DA in activating autophagy, suggesting that DA could serve as a new and potential chemopreventive agent for treating human oral cancer. PMID:26356821
Correlation of MET gene amplification and TP53 mutation with PD-L1 expression in non-small cell lung cancer

PubMed Central

Albitar, Maher; Sudarsanam, Sucha; Ma, Wanlong; Jiang, Shiping; Chen, Wayne; Funari, Vincent; Blocker, Forrest; Agersborg, Sally

2018-01-01

Background The role of MET amplification in lung cancer, particularly in relation to checkpoint inhibition and EGFR WT, has not been fully explored. In this study, we correlated PD-L1 expression with MET amplification and EGFR, KRAS, or TP53 mutation in primary lung cancer. Methods In this retrospective study, tissue collected from 471 various tumors, including 397 lung cancers, was tested for MET amplification by FISH with a MET/centromere probe. PD-L1 expression was evaluated using clone SP142 and standard immunohistochemistry, and TP53, KRAS, and EGFR mutations were tested using next generation sequencing. Results Our results revealed that PD-L1 expression in non-small cell lung cancer is inversely correlated with EGFR mutation (P=0.0003), and positively correlated with TP53 mutation (P=0.0001) and MET amplification (P=0.004). Patients with TP53 mutations had significantly higher MET amplification (P=0.007), and were more likely (P=0.0002) to be EGFR wild type. There was no correlation between KRAS mutation and overall PD-L1 expression, but significant positive correlation between PD-L1 expression and KRAS with TP53 co-mutation (P=0.0002). A cut-off for the ratio of MET: centromere signal was determined as 1.5%, and 4% of lung cancer patients were identified as MET amplified. Conclusions This data suggests that in lung cancer both MET and TP53 play direct roles in regulating PD-L1 opposing EGFR. Moreover, KRAS and TP53 co-mutation may cooperate to drive PD-L1 expression in lung cancer. Adding MET or TP53 inhibitors to checkpoint inhibitors may be an attractive combination therapy in patients with lung cancer and MET amplification. PMID:29568386
Hepatitis C virus Core overcomes all-trans retinoic acid-induced apoptosis in human hepatoma cells by inhibiting p14 expression via DNA methylation

PubMed Central

Kwak, Juri; Choi, Jung-Hye; Jang, Kyung Lib

2017-01-01

All-trans retinoic acid (ATRA), the most biologically active metabolite of vitamin A, is known to induce p14 expression via promoter hypomethylation to activate the p14-MDM2-p53 pathway, which leads to activation of the p53-dependent apoptotic pathway and subsequent induction of apoptosis in human hepatoma cells. In the present study, we found that hepatitis C virus (HCV) Core derived from ectopic expression or HCV infection overcomes ATRA-induced apoptosis in p53-positive hepatoma cells. For this effect, HCV Core upregulated both protein levels and enzyme activities of DNA methyltransferase 1 (DNMT1), DNMT3a, and DNMT3b and thereby repressed p14 expression via promoter hypermethylation, resulting in inactivation of the pathway leading to p53 accumulation in the presence of ATRA. As a result, HCV Core prevented ATRA from activating several apoptosis-related molecules, including Bax, p53 upregulated modulator of apoptosis, caspase-9, caspase-3, and poly (ADP-ribose) polymerase. In addition, complementation of p14 in the Core-expressing cells by either ectopic expression or treatment with 5-Aza-2′dC almost completely abolished the potential of HCV Core to suppress ATRA-induced apoptosis. Based on these observations, we conclude that HCV Core executes its oncogenic potential by suppressing the p53-dependent apoptosis induced by ATRA in human hepatoma cells. PMID:29156743
The Neuronal Ischemic Tolerance Is Conditioned by the Tp53 Arg72Pro Polymorphism.

PubMed

Ramos-Araque, Maria E; Rodriguez, Cristina; Vecino, Rebeca; Cortijo Garcia, Elisa; de Lera Alfonso, Mercedes; Sanchez Barba, Mercedes; Colàs-Campàs, Laura; Purroy, Francisco; Arenillas, Juan F; Almeida, Angeles; Delgado-Esteban, Maria

2018-04-23

Cerebral preconditioning (PC) confers endogenous brain protection after stroke. Ischemic stroke patients with a prior transient ischemic attack (TIA) may potentially be in a preconditioned state. Although PC has been associated with the activation of pro-survival signals, the mechanism by which preconditioning confers neuroprotection is not yet fully clarified. Recently, we have described that PC-mediated neuroprotection against ischemic insult is promoted by p53 destabilization, which is mediated by its main regulator MDM2. Moreover, we have previously described that the human Tp53 Arg72Pro single nucleotide polymorphism (SNP) controls susceptibility to ischemia-induced neuronal apoptosis and governs the functional outcome of patients after stroke. Here, we studied the contribution of the human Tp53 Arg72Pro SNP on PC-induced neuroprotection after ischemia. Our results showed that cortical neurons expressing the Pro72-p53 variant exhibited higher PC-mediated neuroprotection as compared with Arg72-p53 neurons. PC prevented ischemia-induced nuclear and cytosolic p53 stabilization in Pro72-p53 neurons. However, PC failed to prevent mitochondrial p53 stabilization, which occurs in Arg72-p53 neurons after ischemia. Furthermore, PC promoted neuroprotection against ischemia by controlling the p53/active caspase-3 pathway in Pro72-p53, but not in Arg72-p53 neurons. Finally, we found that good prognosis associated to TIA within 1 month prior to ischemic stroke was restricted to patients harboring the Pro72 allele. Our findings demonstrate that the Tp53 Arg72Pro SNP controls PC-promoted neuroprotection against a subsequent ischemic insult by modulating mitochondrial p53 stabilization and then modulates TIA-induced ischemic tolerance.
p53 expression and mutation analysis of odontogenic cysts with and without dysplasia.

PubMed

Cox, Darren P

2012-01-01

Overexpression of p53 protein is well described in odontogenic cystic lesions (OCLs), including those with epithelial dysplasia; however, most p53 antibodies stain both wild-type and mutated p53 protein and may not reflect genotype. Direct sequencing of the p53 gene has not identified mutations in OCLs with dysplasia. The purpose of this study was to determine the molecular basis of p53 expression in several types of OCLs with and without dysplasia. The study material comprised 13 OCLs: odontogenic keratocyst (n = 5), orthokeratinized odontogenic cyst (n = 5), dentigerous cyst (n = 2), lateral periodontal cyst (n = 1), and unspecified developmental odontogenic cyst (UDOC) (n = 1). Five of these had features of mild or moderate epithelial dysplasia. One intraosseous squamous cell carcinoma (SCC) that was believed to have arisen from an antecedent dysplastic orthokeratinized OC was also included. Immunohistochemistry was performed using the DO7 monoclonal antibody that recognizes wild-type and mutated p53. DNA was extracted from microdissected tissue for all samples and exons 4 to 8 of the p53 gene direct sequenced. In 4 of 5 OCLs with dysplasia there was strong nuclear staining of basal and suprabasal cells. In all cases without dysplasia, nuclear expression in basal cells was either negative or weak and was absent in suprabasal cell nuclei. A mutation in exon 6 of the p53 gene (E224D) was identified in both the dysplastic orthokeratinized OC and the subsequent intraosseous SCC. OCLs with features of dysplasia show increased expression of p53 protein that does not reflect p53 mutational status. One dysplastic OC shared the same p53 mutation with a subsequent intraosseous SCC, indicating that p53 mutation may be associated with malignant transformation in this case. Copyright © 2012 Elsevier Inc. All rights reserved.
Regulators of apoptosis in cholangiocarcinoma.

PubMed

Jhala, Nirag C; Vickers, Selwyn M; Argani, Pedram; McDonald, Jay M

2005-04-01

Dysregulation of mediators of apoptosis is associated with carcinogenesis. For biliary duct cancers, p53 gene mutation is an important contributor to carcinogenesis. Mutations in the p53 gene affect transcription of the Fas gene, resulting in lack of Fas expression on cell membrane. It has been previously shown that cloned Fas-negative but not Fas-positive human cholangiocarcinoma cells are resistant to anti-Fas-mediated apoptosis and develop tumors in nude mice. In addition, interferon gamma induces Fas expression in Fas-negative cholangiocarcinoma cells and makes them susceptible to apoptosis. Therefore, it becomes important to characterize immunophenotypic expression of p53 and Fas in normal and neoplastic human tissues of the biliary tract to further understand the pathogenesis of the disease. To date, human studies to characterize differences in immunophenotypic expression of the Fas protein between intrahepatic and extrahepatic biliary duct cancers and in their precursor lesions have not been performed. To report the immunophenotypic expression of p53 and Fas expression in various stages in the development of bile duct cancers (intrahepatic and extrahepatic tumor location) and their association with tumor differentiation. Thirty bile duct cancer samples (13 intrahepatic and 17 extrahepatic) from 18 men and 12 women who ranged in age from 44 to 77 years (mean age, 65.6 years) were retrieved from the surgical pathology files. Hematoxylin-eosin-stained slides were evaluated for the type and grade of tumor and dysplastic changes in the biliary tract epithelium. Additional slides were immunohistochemically stained with p53 and anti-Fas mouse monoclonal antibody. The pattern of Fas distribution and percentage of cells positive for p53 and Fas expression were determined. The percentage of Fas-expressing cells is significantly (P = .01) more frequently noted in extrahepatic tumors compared with intrahepatic tumors. Furthermore, Fas expression decreased from dysplastic epithelium to cholangiocarcinoma (P = .01), and this decreasing trend continued from well to poorly differentiated tumors. Nuclear p53 expression was not identified in normal and dysplastic epithelium but was noted in 30% of carcinomas (P = .02). Fas expression is an early event in pathogenesis of bile duct cancers. Immunophenotypic expression of Fas is associated with well to moderately differentiated tumors but not with poor tumor differentiation.
Human T-Cell Leukemia Virus I Tax Protein Sensitizes p53-Mutant Cells to DNA Damage

PubMed Central

Mihaylova, Valia T.; Green, Allison M.; Khurgel, Moshe; Semmes, Oliver J.; Kupfer, Gary M.

2018-01-01

Mutations in p53 are a common cause of resistance of cancers to standard chemotherapy and, thus, treatment failure. Reports have shown that Tax, a human T-cell leukemia virus type I encoded protein that has been associated with genomic instability and perturbation of transcription and cell cycle, sensitizes HeLa cells to UV treatment. The extent to which Tax can sensitize cells and the mechanism by which it exerts its effect are unknown. In this study, we show that Tax sensitizes p53-mutant cells to a broad range of DNA-damaging agents, including mitomycin C, a bifunctional alkylator, etoposide, a topoisomerase II drug, and UV light, but not ionizing radiation, a double-strand break agent, or vinblastine, a tubulin poison. Tax caused hypersensitivity in all p53-deleted cell lines and several, but not all, mutant-expressed p53–containing cell lines, while unexpectedly being protective in p53 wild-type (wt) cells. The effect observed in p53-deleted lines could be reversed for this by transfection of wt p53. We also show that Tax activates a p53-independent proapoptotic program through decreased expression of the retinoblastoma protein and subsequent increased E2F1 expression. The expression of several proapoptotic proteins was also induced by Tax, including Puma and Noxa, culminating in a substantial increase in Bax dimerization. Our results show that Tax can sensitize p53-mutant cells to DNA damage while protecting p53 wt cells, a side benefit that might result in reduced toxicity in normal cells. Such studies hold the promise of a novel adjunctive therapy that could make cancer chemotherapy more effective. PMID:18559532
High-Affinity Rb Binding, p53 Inhibition, Subcellular Localization, and Transformation by Wild-Type or Tumor-Derived Shortened Merkel Cell Polyomavirus Large T Antigens

PubMed Central

Borchert, Sophie; Czech-Sioli, Manja; Neumann, Friederike; Schmidt, Claudia; Wimmer, Peter; Dobner, Thomas

2014-01-01

ABSTRACT Interference with tumor suppressor pathways by polyomavirus-encoded tumor antigens (T-Ags) can result in transformation. Consequently, it is thought that T-Ags encoded by Merkel cell polyomavirus (MCPyV), a virus integrated in ∼90% of all Merkel cell carcinoma (MCC) cases, are major contributors to tumorigenesis. The MCPyV large T-Ag (LT-Ag) has preserved the key functional domains present in all family members but has also acquired unique regions that flank the LxCxE motif. As these regions may mediate unique functions, or may modulate those shared with T-Ags of other polyomaviruses, functional studies of MCPyV T-Ags are required. Here, we have performed a comparative study of full-length or MCC-derived truncated LT-Ags with regard to their biochemical characteristics, their ability to bind to retinoblastoma (Rb) and p53 proteins, and their transforming potential. We provide evidence that full-length MCPyV LT-Ag may not directly bind to p53 but nevertheless can significantly reduce p53-dependent transcription in reporter assays. Although early region expression constructs harboring either full-length or MCC-derived truncated LT-Ag genes can transform primary baby rat kidney cells, truncated LT-Ags do not bind to p53 or reduce p53-dependent transcription. Interestingly, shortened LT-Ags exhibit a very high binding affinity for Rb, as shown by coimmunoprecipitation and in vitro binding studies. Additionally, we show that truncated MCPyV LT-Ag proteins are expressed at higher levels than those for the wild-type protein and are able to partially relocalize Rb to the cytoplasm, indicating that truncated LT proteins may have gained additional features that distinguish them from the full-length protein. IMPORTANCE MCPyV is one of the 12 known polyomaviruses that naturally infect humans. Among these, it is of particular interest since it is the only human polyomavirus known to be involved in tumorigenesis. MCPyV is thought to be causally linked to MCC, a rare skin tumor. In these tumors, viral DNA is monoclonally integrated into the genome of the tumor cells in up to 90% of all MCC cases, and the integrated MCV genomes, furthermore, harbor signature mutations in the so-called early region that selectively abrogate viral replication while preserving cell cycle deregulating functions of the virus. This study describes comparative studies of early region T-Ag protein characteristics, their ability to bind to Rb and p53, and their transforming potential. PMID:24371076
Minnelide/Triptolide Impairs Mitochondrial Function by Regulating SIRT3 in P53-Dependent Manner in Non-Small Cell Lung Cancer.

PubMed

Kumar, Ajay; Corey, Catherine; Scott, Iain; Shiva, Sruti; D'Cunha, Jonathan

2016-01-01

Minnelide/Triptolide (TL) has recently emerged as a potent anticancer drug in non-small cell lung cancer (NSCLC). However, the precise mechanism of its action remains ambiguous. In this study, we elucidated the molecular basis for TL-induced cell death in context to p53 status. Cell death was attributed to dysfunction of mitochondrial bioenergetics in p53-deficient cells, which was characterized by decreased mitochondrial respiration, steady-state ATP level and membrane potential, but augmented reactive oxygen species (ROS). Increased ROS production resulted in oxidative stress in TL-treated cells. This was exhibited by elevated nuclear levels of a redox-sensitive transcriptional factor, NF-E2-related factor-2 (NRF2), along with diminished cellular glutathione (GSH) content. We further demonstrated that in the absence of p53, TL blunted the expression of mitochondrial SIRT3 triggering increased acetylation of NDUAF9 and succinate dehydrogenase, components of complexes I and II of the electron transport chain (ETC). TL-mediated hyperacetylation of complexes I and II proteins and these complexes displayed decreased enzymatic activities. We also provide the evidence that P53 regulate steady-state level of SIRT3 through Proteasome-Pathway. Finally, forced overexpression of Sirt3, but not deacetylase-deficient mutant of Sirt3 (H243Y), restored the deleterious effect of TL on p53-deficient cells by rescuing mitochondrial bioenergetics. On contrary, Sirt3 deficiency in the background of wild-type p53 triggered TL-induced mitochondrial impairment that echoed TL effect in p53-deficeint cells. These findings illustrate a novel mechanism by which TL exerts its potent effects on mitochondrial function and ultimately the viability of NSCLC tumor.
Suppression of HPV E6 and E7 expression by BAF53 depletion in cervical cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Kiwon; Lee, Ah-Young; Kwon, Yunhee Kim

Highlights: {yields} Integration of HPV into host genome critical for activation of E6 and E7 oncogenes. {yields} BAF53 is essential for higher-order chromatin structure. {yields} BAF53 knockdown suppresses E6 and E7 from HPV integrants, but not from episomal HPVs. {yields} BAF53 knockdown decreases H3K9Ac and H4K12Ac on P105 promoter of integrated HPV 18. {yields} BAF53 knockdown restores the p53-dependent signaling pathway in HeLa and SiHa cells. -- Abstract: Deregulation of the expression of human papillomavirus (HPV) oncogenes E6 and E7 plays a pivotal role in cervical carcinogenesis because the E6 and E7 proteins neutralize p53 and Rb tumor suppressor pathways,more » respectively. In approximately 90% of all cervical carcinomas, HPVs are found to be integrated into the host genome. Following integration, the core-enhancer element and P105 promoter that control expression of E6 and E7 adopt a chromatin structure that is different from that of episomal HPV, and this has been proposed to contribute to activation of E6 and E7 expression. However, the molecular basis underlying this chromatin structural change remains unknown. Previously, BAF53 has been shown to be essential for the integrity of higher-order chromatin structure and interchromosomal interactions. Here, we examined whether BAF53 is required for activated expression of E6 and E7 genes. We found that BAF53 knockdown led to suppression of expression of E6 and E7 genes from HPV integrants in cervical carcinoma cell lines HeLa and SiHa. Conversely, expression of transiently transfected HPV18-LCR-Luciferase was not suppressed by BAF53 knockdown. The level of the active histone marks H3K9Ac and H4K12Ac on the P105 promoter of integrated HPV 18 was decreased in BAF53 knockdown cells. BAF53 knockdown restored the p53-dependent signaling pathway in HeLa and SiHa cells. These results suggest that activated expression of the E6 and E7 genes of integrated HPV is dependent on BAF53-dependent higher-order chromatin structure or nuclear motor activity.« less
Monitoring p53 by MDM2 and MDMX is required for endocrine pancreas development and function in a spatio-temporal manner.

PubMed

Zhang, Yiwei; Zeng, Shelya X; Hao, Qian; Lu, Hua

2017-03-01

Although p53 is not essential for normal embryonic development, it plays a pivotal role in many biological and pathological processes, including cell fate determination-dependent and independent events and diseases. The expression and activity of p53 largely depend on its two biological inhibitors, MDM2 and MDMX, which have been shown to form a complex in order to tightly control p53 to an undetectable level during early stages of embryonic development. However, more delicate studies using conditional gene-modification mouse models show that MDM2 and MDMX may function separately or synergistically on p53 regulation during later stages of embryonic development and adulthood in a cell and tissue-specific manner. Here, we report the role of the MDM2/MDMX-p53 pathway in pancreatic islet morphogenesis and functional maintenance, using mouse lines with specific deletion of MDM2 or MDMX in pancreatic endocrine progenitor cells. Interestingly, deletion of MDM2 results in defects of embryonic endocrine pancreas development, followed by neonatal hyperglycemia and lethality, by inducing pancreatic progenitor cell apoptosis and inhibiting cell proliferation. However, unlike MDM2-knockout animals, mice lacking MDMX in endocrine progenitor cells develop normally. But, surprisingly, the survival rate of adult MDMX-knockout mice drastically declines compared to control mice, as blockage of neonatal development of endocrine pancreas by inhibition of cell proliferation and subsequent islet dysfunction and hyperglycemia eventually lead to type 1 diabetes-like disease with advanced diabetic nephropathy. As expected, both MDM2 and MDMX deletion-caused pancreatic defects are completely rescued by loss of p53, verifying the crucial role of the MDM2 and/or MDMX in regulating p53 in a spatio-temporal manner during the development, functional maintenance, and related disease progress of endocrine pancreas. Also, our study suggests a possible mouse model of advanced diabetic nephropathy, which is complementary to other established diabetic models and perhaps useful for the development of anti-diabetes therapies. Copyright © 2017 Elsevier Inc. All rights reserved.
ATM and p53 combined analysis predicts survival in glioblastoma multiforme patients: A clinicopathologic study.

PubMed

Romano, Francesco Jacopo; Guadagno, Elia; Solari, Domenico; Borrelli, Giorgio; Pignatiello, Sara; Cappabianca, Paolo; Del Basso De Caro, Marialaura

2018-06-01

Glioblastoma is one of the most malignant cancers, with a distinguishing dismal prognosis: surgery followed by chemo- and radiotherapy represents the current standard of care, and chemo- and radioresistance underlie disease recurrence and short overall survival of patients suffering from this malignancy. ATM is a kinase activated by autophosphorylation upon DNA doublestrand breaks arising from errors during replication, byproducts of metabolism, chemotherapy or ionizing radiations; TP53 is one of the most popular tumor suppressor, with a preeminent role in DNA damage response and repair. To study the effects of the immunohistochemical expression of p-ATM and p53 in glioblastoma patients, 21 cases were retrospectively examined. In normal brain tissue, p-ATM was expressed only in neurons; conversely, in tumors cells, the protein showed a variable cytoplasmic expression (score: +,++,+++), with being completely undetectable in three cases. Statistical analysis revealed that high p-ATM score (++/+++) strongly correlated to shorter survival (P = 0.022). No difference in overall survival was registered between p53 normally expressed (NE) and overexpressed (OE) glioblastoma patients (P = 0.669). Survival analysis performed on the results from combined assessment of the two proteins showed that patients with NE p53 /low pATM score had longer overall survival than the NE p53/ high pATM score counterpart. Cox-regression analysis confirmed this finding (HR = 0.025; CI 95% = 0.002-0.284; P = 0.003). Our study outlined the immunohistochemical expression of p-ATM/p53 in glioblastomas and provided data on their possible prognostic/predictive of response role. A "non-oncogene addiction" to ATM for NEp53 glioblastoma could be postulated, strengthening the rationale for development of ATM inhibiting drugs. © 2018 Wiley Periodicals, Inc.
Opposite regulation of MDM2 and MDMX expression in acquisition of mesenchymal phenotype in benign and cancer cells.

PubMed

Slabáková, Eva; Kharaishvili, Gvantsa; Smějová, Monika; Pernicová, Zuzana; Suchánková, Tereza; Remšík, Ján; Lerch, Stanislav; Straková, Nicol; Bouchal, Jan; Král, Milan; Culig, Zoran; Kozubík, Alois; Souček, Karel

2015-11-03

Plasticity of cancer cells, manifested by transitions between epithelial and mesenchymal phenotypes, represents a challenging issue in the treatment of neoplasias. Both epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are implicated in the processes of metastasis formation and acquisition of stem cell-like properties. Mouse double minute (MDM) 2 and MDMX are important players in cancer progression, as they act as regulators of p53, but their function in EMT and metastasis may be contradictory. Here, we show that the EMT phenotype in multiple cellular models and in clinical prostate and breast cancer samples is associated with a decrease in MDM2 and increase in MDMX expression. Modulation of EMT-accompanying changes in MDM2 expression in benign and transformed prostate epithelial cells influences their migration capacity and sensitivity to docetaxel. Analysis of putative mechanisms of MDM2 expression control demonstrates that in the context of defective p53 function, MDM2 expression is regulated by EMT-inducing transcription factors Slug and Twist. These results provide an alternative context-specific role of MDM2 in EMT, cell migration, metastasis, and therapy resistance.
Mutant p53 expression in fallopian tube epithelium drives cell migration.

PubMed

Quartuccio, Suzanne M; Karthikeyan, Subbulakshmi; Eddie, Sharon L; Lantvit, Daniel D; Ó hAinmhire, Eoghainín; Modi, Dimple A; Wei, Jian-Jun; Burdette, Joanna E

2015-10-01

Ovarian cancer is the fifth leading cause of cancer death among US women. Evidence supports the hypothesis that high-grade serous ovarian cancers (HGSC) may originate in the distal end of the fallopian tube. Although a heterogeneous disease, 96% of HGSC contain mutations in p53. In addition, the "p53 signature," or overexpression of p53 protein (usually associated with mutation), is a potential precursor lesion of fallopian tube derived HGSC suggesting an essential role for p53 mutation in early serous tumorigenesis. To further clarify p53-mutation dependent effects on cells, murine oviductal epithelial cells (MOE) were stably transfected with a construct encoding for the R273H DNA binding domain mutation in p53, the most common mutation in HGSC. Mutation in p53 was not sufficient to transform MOE cells but did significantly increase cell migration. A similar p53 mutation in murine ovarian surface epithelium (MOSE), another potential progenitor cell for serous cancer, was not sufficient to transform the cells nor change migration suggesting tissue specific effects of p53 mutation. Microarray data confirmed expression changes of pro-migratory genes in p53(R273H) MOE compared to parental cells, which could be reversed by suppressing Slug expression. Combining p53(R273H) with KRAS(G12V) activation caused transformation of MOE into high-grade sarcomatoid carcinoma when xenografted into nude mice. Elucidating the specific role of p53(R273H) in the fallopian tube will improve understanding of changes at the earliest stage of transformation. This information can help develop chemopreventative strategies to prevent the accumulation of additional mutations and reverse progression of the "p53 signature" thereby, improving survival rates. © 2015 UICC.
Cytoplasmic ASPP1 inhibits apoptosis through the control of YAP

PubMed Central

Vigneron, Arnaud M.; Ludwig, Robert L.; Vousden, Karen H.

2010-01-01

The ASPP (apoptosis-stimulating protein of p53) family of proteins can function in the nucleus to modulate the transcriptional activity of p53, with ASPP1 and ASPP2 contributing to the expression of apoptotic target genes. In this study, we describe a new function for cytoplasmic ASPP1 in controlling YAP (Yes-associated protein)/TAZ. ASPP1 can inhibit the interaction of YAP with LATS1 (large tumor suppressor 1), a kinase that phosphorylates YAP/TAZ and promotes cytoplasmic sequestration and protein degradation. This function of ASPP1 therefore enhances nuclear accumulation of YAP/TAZ and YAP/TAZ-dependent transcriptional regulation. The consequence of YAP/TAZ activation by ASPP1 is to inhibit apoptosis, in part through the down-regulation of Bim expression, leading to resistance to anoikis and enhanced cell migration. These results reveal a potential oncogenic role for cytoplasmic ASPP1, in contrast to the tumor-suppressive activity described previously for nuclear ASPP1. PMID:21041411
Development of Novel Nonagonist PPAR-Gamma Ligands for Lung Cancer Treatment

DTIC Science & Technology

2016-08-01

Affymetrix gene expression profiling. To get the purest representation of this gene set, we generated fibroblasts from the brown adipose tissue of mice... tissues . It has been shown that p53 plays an important role in metabolism and adipose tissue function, and this may be modulated by PPARγ expression as...presentations. Poster Presentation: Melin J. Khandekar, Alex S. Banks , Dina Laznik- Bogoslavski, James P. White, Jang H. Choi, Kwok-kin Wong, Ted

Long noncoding RNA MEG3 mediated angiogenesis after cerebral infarction through regulating p53/NOX4 axis.

PubMed

Zhan, Renya; Xu, Kangli; Pan, Jianwei; Xu, Qingsheng; Xu, Shengjie; Shen, Jian

2017-08-26

This study aimed to explore the mechanism of lncRNA MEG3 on angiogenesis after cerebral infarction (CI). The rat brain microvascular endothelial cells (RBMVECs) isolated from rat was used to establish CI model, which were treated with oxygen-glucose deprivation/reoxygenation (OGD/R). The genes mRNA and protein expression levels in RBMVECs were determined by the quantitative real-time polymerase chain reaction (RT-qPCR) and western blot, respectively. The flow cytometry was used to measured cell apoptosis and intracellular reactive oxygen species (ROS) generation. The RBMVECs activities was detected by MTT method. The RNA-immunoprecipitation (RIP) assay was used to detect the interaction between MEG3 and p53, and the relationship between p53 and NOX4 was proved by chromatin co-immunoprecipitation (chip) assay. The results showed that OGD or OGD/R increased MEG3 and NOX4 expression, and there was positive correlation between MEG3 and NOX4 expression in RBMVECs. Next, knockdown of MEG3 indicated that inhibition of MEG3 was conducive to protect RBMVECs against OGD/R-induced apoptosis, with decreased NOX4 and p53 expression, further enhanced pro-angiogenic factors (HIF-1α and VEGF) expression, and reduced intracellular ROS generation. And then the RIP and CHIP assay demonstrated that MEG3 could interacted with p53 and regulated its expression, and p53 exerted significant binding in the promoters for NOX4, suggesting that MEG3 regulated NOX4 expression via p53. At last, knockdown of NOX4 indicated that inhibition of NOX4 protected RBMVECs against OGD/R-induced apoptosis, with increased cell viability and pro-angiogenic factors expression, and reduced ROS generation. LncRNA MEG3 was an important regulator in OGD/R induced-RBMVECs apoptosis and the mechanism of MEG3 on angiogenesis after CI was reduced ROS by p53/NOX4 axis. Copyright © 2017 Elsevier Inc. All rights reserved.
Preliminary report on the effect of brachytherapy on expression of p53, bc1-2 and apoptosis in squamous cell carcinoma of the oesophagus.

PubMed

Sur, Monalisa; Sur, Ranjan K; Cooper, Kum; Bizos, Damon

2003-02-01

Pre-brachytherapy biopsies and post-brachytherapy oesophagectomy specimens of 10 patients with early squamous cell carcinoma of the middle third of the oesophagus were examined for the expression of p53, bcl-2 and apoptosis using immunohistochemical markers. There was no expression of p53 in one patient in both pre- and post-brachytherapy specimens. In 8 patients, p53 staining was strongly positive (3+) with approximately 50% or more cells, and with diffuse and no specific pattern in the pre-brachytherapy biopsies. The tumour areas of the post-brachytherapy specimens of this group showed strong 3+ positivity with p53 (10-50% positive cell count), with the pattern being focal and peripheral in the tumour islands. The centre of the tumour islands showed necrosis and/or keratinisation. In one patient, the pre-brachytherapy biopsy showed expression of p53 while the post-brachytherapy specimen was negative. bcl-2 expression in both pre- and post-brachytherapy was equivocal and inconclusive in both the pre- and post-brachytherapy specimens. Apoptosis was negative in all the pre- and post-brachytherapy tissue sections in the presence of positive controls. Brachytherapy does not cause cell death by apoptosis but by necrosis and maturation of the cells into better differentiated cells, which is caused by OH free radical, and induction of the keratin gene respectively. It is possible that brachytherapy may cause destruction of cells containing wild-type p53, while mutant p53 in cells located at the tumour periphery escape the effect of brachytherapy. This may be responsible for the high incidence of local recurrence and distant metastasis in oesophageal cancer treated with radiotherapy. There is no effect of brachytherapy on bcl-2 expression in oesophageal cancer.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Youn-hee; Kim, Donghern; Dai, Jin

Occupational and environmental exposure to arsenic (III) and chromium VI (Cr(VI)) have been confirmed to cause lung cancer. Mechanisms of these metals carcinogenesis are still under investigation. Selection of cell lines to be used is essential for the studies. Human bronchial epithelial BEAS-2B cells are the cells to be utilized by most of scientists. However, due to p53 missense mutation (CCG → TCG) at codon 47 and the codon 72 polymorphism (CGC → CCC) in BEAS-2B cells, its usage has frequently been questioned. The present study has examined activity and expression of 53 and its downstream target protein p21 uponmore » acute or chronic exposure of BEAS-2B cells to arsenic and Cr(VI). The results show that short-term exposure of BEAS-2B cells to arsenic or Cr(VI) was able to activate both p53 and p21. Chronic exposure of BEAS-2B cells to these two metals caused malignant cell transformation and tumorigenesis. In arsenic-transformed BEAS-2B cells reductions in p53 promoter activity, mRNA expression, and phosphorylation of p53 at Ser392 were observed, while the total p53 protein level remained the same compared to those in passage-matched parent ones. p21 promoter activity and expression were decreased in arsenic-transformed cells. Cr(VI)-transformed cells exhibit elevated p53 promoter activity, mRNA expression, and phosphorylation at Ser15, but reduced phosphorylation at Ser392 and total p53 protein level compared to passage-matched parent ones. p21 promoter activity and expression were elevated in Cr(VI)-transformed cells. These results demonstrate that p53 is able to respond to exposure of arsenic or Cr(VI), suggesting that BEAS-2B cells are an appropriate in vitro model to investigate arsenic or Cr(VI) induced lung cancer. - Highlights: • Short-term exposure of BEAS-2B cells to arsenic or Cr(VI) activates p53 and p21. • Chronic exposure of BEAS-2B cells to arsenic or Cr(VI) causes cell transformation and tumorigenesis. • Arsenic-transformed cells exhibit reduced activities of p53 and p21. • Cr(VI)-transformed cells exhibit increased activities of p53 and p21.« less
Chaperone-mediated autophagy degrades mutant p53

PubMed Central

Vakifahmetoglu-Norberg, Helin; Kim, Minsu; Xia, Hong-guang; Iwanicki, Marcin P.; Ofengeim, Dimitry; Coloff, Jonathan L.; Pan, Lifeng; Ince, Tan A.; Kroemer, Guido; Brugge, Joan S.; Yuan, Junying

2013-01-01

Missense mutations in the gene TP53, which encodes p53, one of the most important tumor suppressors, are common in human cancers. Accumulated mutant p53 proteins are known to actively contribute to tumor development and metastasis. Thus, promoting the removal of mutant p53 proteins in cancer cells may have therapeutic significance. Here we investigated the mechanisms that govern the turnover of mutant p53 in nonproliferating tumor cells using a combination of pharmacological and genetic approaches. We show that suppression of macroautophagy by multiple means promotes the degradation of mutant p53 through chaperone-mediated autophagy in a lysosome-dependent fashion. In addition, depletion of mutant p53 expression due to macroautophagy inhibition sensitizes the death of dormant cancer cells under nonproliferating conditions. Taken together, our results delineate a novel strategy for killing tumor cells that depend on mutant p53 expression by the activation of chaperone-mediated autophagy and potential pharmacological means to reduce the levels of accumulated mutant p53 without the restriction of mutant p53 conformation in quiescent tumor cells. PMID:23913924
Expression of regulatory proteins and proliferative activity in relation to phenotypic characteristics of upper urothelial carcinoma.

PubMed

Dolićanin, Zana; Velicković, Ljubinka Janković; Djordjević, Biljana; Visnjić, Milan; Pesić, Ivana; Ristić, Ana; Marjanović, Vesna

2011-07-01

Deregulation of the normal cell cycle is common in upper urothelial carcinoma (UUC). The aim of this study was to investigate the expression of regulatory proteins of the cell cycle (p53, p16, cyclin D1, HER-2) and proliferative Ki-67 activity in UUC, and to determine their interaction and influence on the phenotypic characteristics of UUC. In 44 patients with UUC, histopathological and immunohistochemical analyses (p53, p16, cyclin D1, HER-2, and Ki-67) of tumors were done. Overexpression/altered expression of p53, p16, cyclin D1 or HER-2 was detected in 20%, 57%, 64%, and 57% of tumors, respectively. Eleven (25%) UUC had a high proliferative Ki-67 index. Forty patients (91%) had at least one marker altered, while four (9%) tumors had a wild-type status. Analysis of relationship between expressions of molecular markers showed that only high expression of p53 was significantly associated with altered p16 activity (p < 0.05). High Ki-67 index was associated with the high stage (p < 0.005), solid growth (p < 0.01), high grade (p < 0.05), and multifocality p < 0.05) of UUC, while high expression of p53 was associated with the solid growth (p < 0.05). In regression models that included all molecular markers and phenotypic characteristics, only Ki-67 correlated with the growth (p < 0.0001), stage (p < 0.01), grade (p < 0.05) and multifocality (p < 0.05) of UCC; (Ki-67 and HER-2 expression correlated with the lymphovascular invasion (p < 0.05). This investigation showed that only negative regulatory proteins of the cell cycle, p53 and p16, were significantly associated in UUC, while proliferative marker Ki-67 was in relation to the key phenotypic characteristics of UUC in the best way.
Molecular markers in dysplasia of the larynx: expression of cyclin-dependent kinase inhibitors p21, p27 and p53 tumour suppressor gene in predicting cancer risk.

PubMed

Jeannon, J-P; Soames, J V; Aston, V; Stafford, F W; Wilson, J A

2004-12-01

Premalignant conditions affect the larynx. Dysplasia can progress in severity resulting in cancer depending on many clinical, pathological and molecular factors. The purpose of this study was to examine the expression of the p21 and p27 cyclin-dependent kinase inhibitors and p53 tumour suppressor gene in dysplasia of the larynx. A total of 114 cases of untreated dysplasia were selected from the archives of the University of Newcastle. p21, p27 and p53 immunohistochemistry was performed and the cases followed up. Twenty-eight dysplasias (24%) subsequently developed into cancers. Expression of the molecular factors studied was not associated with cancer progression. p53 expression was associated with smoking (P = 0.005). In contrast, grade of dysplasia was significantly associated with cancer risk (odds ratio 6.7; P = 0.0001). The majority (75%) of cancers were detected within 12 months of dysplasia being diagnosed.
Expression profiling of cell cycle regulatory proteins in oropharyngeal carcinomas using tissue microarrays.

PubMed

Ribeiro, Daniel A; Nascimento, Fabio D; Fracalossi, Ana Carolina C; Gomes, Thiago S; Oshima, Celina T F; Franco, Marcello F

2010-01-01

The aim of this study was to investigate the expressions of cell cycle regulatory proteins such as p53, p16, p21, and Rb in squamous cell carcinoma of the oropharynx and their relation to histological differentiation, staging of disease, and prognosis. Paraffin blocks from 21 primary tumors were obtained from archives of the Department of Pathology, Paulista Medical School, Federal University of Sao Paulo, UNIFESP/EPM. Immunohistochemistry was used to detect the expression of p53, p16, p21, and Rb by means of tissue microarrays. Expression of p53, p21, p16 and Rb was not correlated with the stage of disease, histopathological grading or recurrence in squamous cell carcinoma of the oropharynx. Taken together, our results suggest that p53, p16, p21 and Rb are not reliable biomarkers for prognosis of the tumor severity or recurrence in squamous cell carcinoma of the oropharynx as depicted by tissue microarrays and immunohistochemistry.
Expression of autophagy-related protein LC3B, p62, and cytoplasmic p53 in human retinoblastoma tissues.

PubMed

Zhang, M; Zhou, Y-F; Gong, J-Y; Gao, C-B; Li, S-L

2016-07-01

Dysfunction of autophagy has been implicated in development and progression of diverse human cancers. However, the exact role and mechanism of autophagy have not been fully understood in human cancers, especially in retinoblastoma (Rb). We determined the autophagy activity in human Rb tissues by assessing the autophagy markers microtubule-associated protein light chain 3B (LC3) and p62 (SQSTM1) in formalin fixed and paraffin embedded human tissue by immunohistochemistry and then associated their expression with patient clinicopathological features. We further explored the correlation between the expression of LC3B and p62 and the expression of cytoplasmic p53, a newly identified autophagy suppressor, in Rb tissues. Our data revealed that the expression of LC3B and p62, was significantly associated with disease progression and tumor invasion of Rb. Furthermore, we also revealed that cytoplasmic expression of p53 was inversely associated with the behavior of tumor invasion. Finally, Spearman correlation analysis demonstrated that cytoplasmic expression of p53 was significantly and inversely correlated to the expression of both LC3B and p62. Autophagy might play an important role in human Rb progression, and LC3B and p62 may be useful predictors of disease progression in patients with Rb.
Combined RAF1 protein expression and p53 mutational status provides a strong predictor of cellular radiosensitivity

PubMed Central

Warenius, H M; Jones, M; Gorman, T; McLeish, R; Seabra, L; Barraclough, R; Rudland, P

2000-01-01

The tumour suppressor gene, p53, and genes coding for positive signal transduction factors can influence transit through cell-cycle checkpoints and modulate radiosensitivity. Here we examine the effects of RAF1 protein on the rate of exit from a G2/M block induced by γ-irradiation in relation to intrinsic cellular radiosensitivity in human cell lines expressing wild-type p53 (wtp53) protein as compared to mutant p53 (mutp53) protein. Cell lines which expressed mutp53 protein were all relatively radioresistant and exhibited no relationship between RAF1 protein and cellular radiosensitivity. Cell lines expressing wtp53 protein, however, showed a strong relationship between RAF1 protein levels and the radiosensitivity parameter SF2. In addition, when post-irradiation perturbation of G2/M transit was compared using the parameter T50 (time after the peak of G2/M delay at which 50% of the cells had exited from a block induced by 2 Gy of irradiation), RAF1 was related to T50 in wtp53, but not mutp53, cell lines. Cell lines which expressed wtp53 protein and high levels of RAF1 had shorter T50s and were also more radiosensitive. These results suggest a cooperative role for wtp53 and RAF1 protein in determining cellular radiosensitivity in human cells, which involves control of the G2/M checkpoint. © 2000 Cancer Research Campaign PMID:10993658
Downregulation of VRK1 by p53 in Response to DNA Damage Is Mediated by the Autophagic Pathway

PubMed Central

Valbuena, Alberto; Castro-Obregón, Susana; Lazo, Pedro A.

2011-01-01

Human VRK1 induces a stabilization and accumulation of p53 by specific phosphorylation in Thr18. This p53 accumulation is reversed by its downregulation mediated by Hdm2, requiring a dephosphorylated p53 and therefore also needs the removal of VRK1 as stabilizer. This process requires export of VRK1 to the cytosol and is inhibited by leptomycin B. We have identified that downregulation of VRK1 protein levels requires DRAM expression, a p53-induced gene. DRAM is located in the endosomal-lysosomal compartment. Induction of DNA damage by UV, IR, etoposide and doxorubicin stabilizes p53 and induces DRAM expression, followed by VRK1 downregulation and a reduction in p53 Thr18 phosphorylation. DRAM expression is induced by wild-type p53, but not by common human p53 mutants, R175H, R248W and R273H. Overexpression of DRAM induces VRK1 downregulation and the opposite effect was observed by its knockdown. LC3 and p62 were also downregulated, like VRK1, in response to UV-induced DNA damage. The implication of the autophagic pathway was confirmed by its requirement for Beclin1. We propose a model with a double regulatory loop in response to DNA damage, the accumulated p53 is removed by induction of Hdm2 and degradation in the proteasome, and the p53-stabilizer VRK1 is eliminated by the induction of DRAM that leads to its lysosomal degradation in the autophagic pathway, and thus permitting p53 degradation by Hdm2. This VRK1 downregulation is necessary to modulate the block in cell cycle progression induced by p53 as part of its DNA damage response. PMID:21386980
Astrocytes Can Adopt Endothelial Cell Fates in a p53-Dependent Manner.

PubMed

Brumm, Andrew J; Nunez, Stefanie; Doroudchi, Mehdi M; Kawaguchi, Riki; Duan, Jinhzu; Pellegrini, Matteo; Lam, Larry; Carmichael, S Thomas; Deb, Arjun; Hinman, Jason D

2017-08-01

Astrocytes respond to a variety of CNS injuries by cellular enlargement, process outgrowth, and upregulation of extracellular matrix proteins that function to prevent expansion of the injured region. This astrocytic response, though critical to the acute injury response, results in the formation of a glial scar that inhibits neural repair. Scar-forming cells (fibroblasts) in the heart can undergo mesenchymal-endothelial transition into endothelial cell fates following cardiac injury in a process dependent on p53 that can be modulated to augment cardiac repair. Here, we sought to determine whether astrocytes, as the primary scar-forming cell of the CNS, are able to undergo a similar cellular phenotypic transition and adopt endothelial cell fates. Serum deprivation of differentiated astrocytes resulted in a change in cellular morphology and upregulation of endothelial cell marker genes. In a tube formation assay, serum-deprived astrocytes showed a substantial increase in vessel-like morphology that was comparable to human umbilical vein endothelial cells and dependent on p53. RNA sequencing of serum-deprived astrocytes demonstrated an expression profile that mimicked an endothelial rather than astrocyte transcriptome and identified p53 and angiogenic pathways as specifically upregulated. Inhibition of p53 with genetic or pharmacologic strategies inhibited astrocyte-endothelial transition. Astrocyte-endothelial cell transition could also be modulated by miR-194, a microRNA downstream of p53 that affects expression of genes regulating angiogenesis. Together, these studies demonstrate that differentiated astrocytes retain a stimulus-dependent mechanism for cellular transition into an endothelial phenotype that may modulate formation of the glial scar and promote injury-induced angiogenesis.
Depletion of hepatoma-derived growth factor-related protein-3 induces apoptotic sensitization of radioresistant A549 cells via reactive oxygen species-dependent p53 activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yun, Hong Shik; Hong, Eun-Hee; Department of Chemistry, College of Natural Sciences, Hanyang University, Seoul 133-791

2013-09-27

Highlights: •HRP-3 is a radiation- and anticancer drug-responsive protein in A549 cells. •Depletion of HRP-3 induces apoptosis of radio- and chemoresistant A549 cells. •Depletion of HRP-3 promotes ROS generation via inhibition of the Nrf2/HO-1 pathway. •Depletion of HRP-3 enhances ROS-dependent p53 activation and PUMA expression. -- Abstract: Biomarkers based on functional signaling have the potential to provide greater insight into the pathogenesis of cancer and may offer additional targets for anticancer therapeutics. Here, we identified hepatoma-derived growth factor-related protein-3 (HRP-3) as a radioresistance-related gene and characterized the molecular mechanism by which its encoded protein regulates the radio- and chemoresistant phenotypemore » of lung cancer-derived A549 cells. Knockdown of HRP-3 promoted apoptosis of A549 cells and potentiated the apoptosis-inducing action of radio- and chemotherapy. This increase in apoptosis was associated with a substantial generation of reactive oxygen species (ROS) that was attributable to inhibition of the Nrf2/HO-1 antioxidant pathway and resulted in enhanced ROS-dependent p53 activation and p53-dependent expression of PUMA (p53 upregulated modulator of apoptosis). Therefore, the HRP-3/Nrf2/HO-1/ROS/p53/PUMA cascade is an essential feature of the A549 cell phenotype and a potential radiotherapy target, extending the range of targets in multimodal therapies against lung cancer.« less
p53 downregulates the Fanconi anaemia DNA repair pathway

PubMed Central

Jaber, Sara; Toufektchan, Eléonore; Lejour, Vincent; Bardot, Boris; Toledo, Franck

2016-01-01

Germline mutations affecting telomere maintenance or DNA repair may, respectively, cause dyskeratosis congenita or Fanconi anaemia, two clinically related bone marrow failure syndromes. Mice expressing p53Δ31, a mutant p53 lacking the C terminus, model dyskeratosis congenita. Accordingly, the increased p53 activity in p53Δ31/Δ31 fibroblasts correlated with a decreased expression of 4 genes implicated in telomere syndromes. Here we show that these cells exhibit decreased mRNA levels for additional genes contributing to telomere metabolism, but also, surprisingly, for 12 genes mutated in Fanconi anaemia. Furthermore, p53Δ31/Δ31 fibroblasts exhibit a reduced capacity to repair DNA interstrand crosslinks, a typical feature of Fanconi anaemia cells. Importantly, the p53-dependent downregulation of Fanc genes is largely conserved in human cells. Defective DNA repair is known to activate p53, but our results indicate that, conversely, an increased p53 activity may attenuate the Fanconi anaemia DNA repair pathway, defining a positive regulatory feedback loop. PMID:27033104
p53 downregulates the Fanconi anaemia DNA repair pathway.

PubMed

Jaber, Sara; Toufektchan, Eléonore; Lejour, Vincent; Bardot, Boris; Toledo, Franck

2016-04-01

Germline mutations affecting telomere maintenance or DNA repair may, respectively, cause dyskeratosis congenita or Fanconi anaemia, two clinically related bone marrow failure syndromes. Mice expressing p53(Δ31), a mutant p53 lacking the C terminus, model dyskeratosis congenita. Accordingly, the increased p53 activity in p53(Δ31/Δ31) fibroblasts correlated with a decreased expression of 4 genes implicated in telomere syndromes. Here we show that these cells exhibit decreased mRNA levels for additional genes contributing to telomere metabolism, but also, surprisingly, for 12 genes mutated in Fanconi anaemia. Furthermore, p53(Δ31/Δ31) fibroblasts exhibit a reduced capacity to repair DNA interstrand crosslinks, a typical feature of Fanconi anaemia cells. Importantly, the p53-dependent downregulation of Fanc genes is largely conserved in human cells. Defective DNA repair is known to activate p53, but our results indicate that, conversely, an increased p53 activity may attenuate the Fanconi anaemia DNA repair pathway, defining a positive regulatory feedback loop.
Training Performed Above Lactate Threshold Decreases p53 and Shelterin Expression in Mice.

PubMed

de Carvalho Cunha, Verusca Najara; Dos Santos Rosa, Thiago; Sales, Marcelo Magalhães; Sousa, Caio Victor; da Silva Aguiar, Samuel; Deus, Lysleine Alves; Simoes, Herbert Gustavo; de Andrade, Rosangela Vieira

2018-06-26

Telomere shortening is associated to sarcopenia leading to functional impairment during aging. There are mechanisms associated with telomere attrition, as well to its protection and repair. Physical training is a factor that attenuates telomere shortening, but little is known about the effects of different exercise intensities on telomere biology. Thus, we evaluated the effects of exercise intensity (moderate vs. high-intensity domain) on gene expression of senescence markers Checkpoint kinase 2 and tumor suppressor ( Chk2 and p53 , respectively), shelterin telomere repeat binding 1 and 2 ( Trf1 / Trf2 ), DNA repair ( Xrcc5 ), telomerase reverse transcriptase ( mTERT ) and telomere length in middle aged mice. Three groups were studied: a control group (CTL) and two groups submitted to swimming at intensities below the lactate threshold (LI group) and above the lactate threshold (HI group) for 40 and 20 min respectively, for 12 weeks. After training, the HI group showed reduction in p53 expression in the muscle, and decreased shelterin complex expression when compared to LI group. No differences were observed between groups for mTERT expression and telomere length. Thus, exercise training in high-intensity domain was more effective on reducing markers of senescence and apoptosis. The higher intensity exercise training also diminished shelterin expression, with no differences in telomere length and mTERT expression. Such results possibly indicate a more effective DNA protection for the higher-intensity exercise training. © Georg Thieme Verlag KG Stuttgart · New York.
p53 nuclear accumulation and ERα expression in ductal hyperplasia of breast in a cohort of 215 Chinese women

PubMed Central

2010-01-01

Introduction Women with ductal hyperplasia including usual ductal hyperplasia (UDH) and atypical ductal hyperplasia (ADH) have an increased risk of developing invasive ductal carcinoma (IDC) of breast. The importance of several molecular markers in breast cancer has been of considerable interest during recent years such as p53 and estrogen receptor alpha (ERα). However, p53 nuclear accumulation and ERα expression have not been assessed in ductal hyperplasia co-existing with ductal carcinoma in situ (DCIS) or IDC versus pure ductal hyperplasia without DCIS or IDC. Materials and methods We investigated p53 nuclear accumulation and ERα expression in breast ductal hyperplasia in a cohort of 215 Chinese women by immunohistochemistry (IHC), which included 129 cases of pure ductal hyperplasia, 86 cases of ductal hyperplasia co-existing with DCIS (41 cases) or IDC (45 cases). Results Nuclear p53 accumulation was identified in 22.8% of ADH (31/136), 41.5% of DCIS (17/41) and 42.2% of IDC (19/45), and no case of UDH (0/79). No difference in nuclear p53 accumulation was observed between pure ADH and ADH co-existing with DCIS (ADH/DCIS) or IDC (ADH/IDC) (P > 0.05). The positive rate of ERα expression was lower in ADH (118/136, 86.8%) than that in UDH (79/79, 100%) (P < 0.001), but higher than that in DCIS (28/41, 68.3%) or IDC (26/45, 57.8%) respectively (P < 0.001). The frequency of ERα expression was lower in ADH/DCIS (23/29, 79.31%) and ADH/IDC (23/30, 76.67%) than that in pure ADH (72/77, 93.51%) respectively (P < 0.05). There was a negative weak correlation between p53 nuclear accumulation and ERα expression as for ADH (coefficient correlation -0.51; P < 0.001). Conclusions Different pathological types of ductal hyperplasia of breast are accompanied by diversity in patterns of nuclear p53 accumulation and ERα expression. At least some pure ADH is molecularly distinct from ADH/CIS or ADH/IDC which indicated the two types of ADH are molecularly distinct entities although they have the same morphological appearance. PMID:20712900
Maspin, p53, p63, and Ki-67 in epithelial lesions of the tongue: from hyperplasia through dysplasia to carcinoma.

PubMed

Vered, Marilena; Allon, Irit; Dayan, Dan

2009-03-01

The pattern of changes in the expression of mammary serine protease inhibitor (maspin) tumor suppressor protein in tongue epithelial lesions [hyperplasia (HP), mild dysplasia (MD), moderate-to-severe dysplasia (MSD) and squamous cell carcinoma (SCC)] was investigated and correlated to the expression of maspin-regulating factors p53 and p63, and the proliferation marker Ki-67. Cases of HP (n = 16), MD (n = 12), MSD (n = 11), and SCC (n = 22) were immunostained for maspin, p53, p63, and Ki-67. Maspin expression was scored separately for the basal, middle, and upper thirds of the epithelial width, and as the total sum of all 'thirds' (maspin-total). p53, p63, and Ki-67 were immuno-morphometrically assessed for the entire epithelial width. Maspin expression was differential and progressive extending to higher epithelial layers as dysplastic changes aggravated and culminated in carcinoma. Strong expression was related to MSD in the middle third and to carcinoma in the upper third. It was frequently lost at the invasion front, where the tumor was less differentiated. The changes in mean scores of maspin-total in the different study groups were positively correlated to the mean scores of p63 (r = 0.5, P < 0.001), p53 (r = 0.4, P = 0.004), and Ki-67 (r = 0.5, P < 0.001). Strong expression of maspin in the middle third of the epithelium may be considered a diagnostic sign of mild-to-moderate dysplasia and an indication of carcinoma in the upper third. The correlations between maspin and controlling factors (e.g. p63 and p53) may be events with key roles in the development of tongue carcinoma.
A global analysis of the complex landscape of isoforms and regulatory networks of p63 in human cells and tissues.

PubMed

Sethi, Isha; Romano, Rose-Anne; Gluck, Christian; Smalley, Kirsten; Vojtesek, Borivoj; Buck, Michael J; Sinha, Satrajit

2015-08-07

The transcription factor p63 belongs to the p53/p63/p73 family and plays key functional roles during normal epithelial development and differentiation and in pathological states such as squamous cell carcinomas. The human TP63 gene, located on chromosome 3q28 is driven by two promoters that generate the full-length transactivating (TA) and N-terminal truncated (ΔN) isoforms. Furthermore alternative splicing at the C-terminus gives rise to additional α, β, γ and likely several other minor variants. Teasing out the expression and biological function of each p63 variant has been both the focus of, and a cause for contention in the p63 field. Here we have taken advantage of a burgeoning RNA-Seq based genomic data-sets to examine the global expression profiles of p63 isoforms across commonly utilized human cell-lines and major tissues and organs. Consistent with earlier studies, we find ΔNp63 transcripts, primarily that of the ΔNp63α isoforms, to be expressed in most cells of epithelial origin such as those of skin and oral tissues, mammary glands and squamous cell carcinomas. In contrast, TAp63 is not expressed in the majority of normal cell-types and tissues; rather it is selectively expressed at moderate to high levels in a subset of Burkitt's and diffuse large B-cell lymphoma cell lines. We verify this differential expression pattern of p63 isoforms by Western blot analysis, using newly developed ΔN and TA specific antibodies. Furthermore using unsupervised clustering of human cell lines, tissues and organs, we show that ΔNp63 and TAp63 driven transcriptional networks involve very distinct sets of molecular players, which may underlie their different biological functions. In this study we report comprehensive and global expression profiles of p63 isoforms and their relationship to p53/p73 and other potential transcriptional co-regulators. We curate publicly available data generated in part by consortiums such as ENCODE, FANTOM and Human Protein Atlas to delineate the vastly different transcriptomic landscapes of ΔNp63 and TAp63. Our studies help not only in dispelling prevailing myths and controversies on p63 expression in commonly used human cell lines but also augur new isoform- and cell type-specific activities of p63.
The Parkinson disease-related protein DJ-1 counteracts mitochondrial impairment induced by the tumour suppressor protein p53 by enhancing endoplasmic reticulum-mitochondria tethering.

PubMed

Ottolini, Denis; Calì, Tito; Negro, Alessandro; Brini, Marisa

2013-06-01

DJ-1 was first identified as an oncogene. More recently, mutations in its gene have been found causative for autosomal recessive familial Parkinson disease. Numerous studies support the DJ-1 role in the protection against oxidative stress and maintenance of mitochondria structure; however, the mechanism of its protective function remains largely unknown. We investigated whether mitochondrial Ca(2+) homeostasis, a key parameter in cell physiology, could be a target for DJ-1 action. Here, we show that DJ-1 modulates mitochondrial Ca(2+) transients induced upon cell stimulation with an 1,4,5-inositol-tris-phosphate agonist by favouring the endoplasmic reticulum (ER)-mitochondria tethering. A reduction of DJ-1 levels results in mitochondria fragmentation and decreased mitochondrial Ca(2+) uptake in stimulated cells. To functionally couple these effects with the well-recognized cytoprotective role of DJ-1, we investigated its action in respect to the tumour suppressor p53. p53 overexpression in HeLa cells impairs their ability to accumulate Ca(2+) in the mitochondrial matrix, causes alteration of the mitochondrial morphology and reduces ER-mitochondria contact sites. Mitochondrial impairments are independent from Drp1 activation, since the co-expression of the dominant negative mutant of Drp1 failed to abolish them. DJ-1 overexpression prevents these alterations by re-establishing the ER-mitochondria tethering. Similarly, the co-expression of the pro-fusion protein Mitofusin 2 blocks the effects induced by p53 on mitochondria, confirming that the modulation of the ER-mitochondria contact sites is critical to mitochondria integrity. Thus, the impairment of ER-mitochondria communication, as a consequence of DJ-1 loss-of-function, may be detrimental for mitochondria-related processes and be at the basis of mitochondrial dysfunction observed in Parkinson disease.
Dual targeting of wild-type and mutant p53 by small molecule RITA results in the inhibition of N-Myc and key survival oncogenes and kills neuroblastoma cells in vivo and in vitro.

PubMed

Burmakin, Mikhail; Shi, Yao; Hedström, Elisabeth; Kogner, Per; Selivanova, Galina

2013-09-15

Restoration of the p53 function in tumors is a promising therapeutic strategy due to the high potential of p53 as tumor suppressor and the fact that established tumors depend on p53 inactivation for their survival. Here, we addressed the question whether small molecule RITA can reactivate p53 in neuroblastoma and suppress the growth of neuroblastoma cells in vitro and in vivo. The ability of RITA to inhibit growth and to induce apoptosis was shown in seven neuroblastoma cell lines. Mechanistic studies were carried out to determine the p53 dependence and the molecular mechanism of RITA-induced apoptosis in neuroblastoma, using cell viability assays, RNAi silencing, co-immunoprecipitation, qPCR, and Western blotting analysis. In vivo experiments were conducted to study the effect of RITA on human neuroblastoma xenografts in mice. RITA induced p53-dependent apoptosis in a set of seven neuroblastoma cell lines, carrying wild-type or mutant p53; it activated p53 and triggered the expression of proapoptotic p53 target genes. Importantly, p53 activated by RITA inhibited several key oncogenes that are high-priority targets for pharmacologic anticancer strategies in neuroblastoma, including N-Myc, Aurora kinase, Mcl-1, Bcl-2, Wip-1, MDM2, and MDMX. Moreover, RITA had a strong antitumor effect in vivo. Reactivation of wild-type and mutant p53 resulting in the induction of proapoptotic factors along with ablation of key oncogenes by compounds such as RITA may be a highly effective strategy to treat neuroblastoma. ©2013 AACR.

p53 Restoration in Induction and Maintenance of Senescence: Differential Effects in Premalignant and Malignant Tumor Cells

PubMed Central

Harajly, Mohamad; Zalzali, Hasan; Nawaz, Zafar; Ghayad, Sandra E.; Ghamloush, Farah; Basma, Hussein; Zainedin, Samiha; Rabeh, Wissam; Jabbour, Mark; Tawil, Ayman; Badro, Danielle A.; Evan, Gerard I.

2015-01-01

The restoration of p53 has been suggested as a therapeutic approach in tumors. However, the timing of p53 restoration in relation to its efficacy during tumor progression still is unclear. We now show that the restoration of p53 in murine premalignant proliferating pineal lesions resulted in cellular senescence, while p53 restoration in invasive pineal tumors did not. The effectiveness of p53 restoration was not dependent on p19Arf expression but showed an inverse correlation with Mdm2 expression. In tumor cells, p53 restoration became effective when paired with either DNA-damaging therapy or with nutlin, an inhibitor of p53-Mdm2 interaction. Interestingly, the inactivation of p53 after senescence resulted in reentry into the cell cycle and rapid tumor progression. The evaluation of a panel of human supratentorial primitive neuroectodermal tumors (sPNET) showed low activity of the p53 pathway. Together, these data suggest that the restoration of the p53 pathway has different effects in premalignant versus invasive pineal tumors, and that p53 activation needs to be continually sustained, as reversion from senescence occurs rapidly with aggressive tumor growth when p53 is lost again. Finally, p53 restoration approaches may be worth exploring in sPNET, where the p53 gene is intact but the pathway is inactive in the majority of examined tumors. PMID:26598601
p53 elevation in human cells halt SV40 infection by inhibiting T-ag expression

PubMed Central

Drayman, Nir; Ben-nun-Shaul, Orly; Butin-Israeli, Veronika; Srivastava, Rohit; Rubinstein, Ariel M.; Mock, Caroline S.; Elyada, Ela; Ben-Neriah, Yinon; Lahav, Galit; Oppenheim, Ariella

2016-01-01

SV40 large T-antigen (T-ag) has been known for decades to inactivate the tumor suppressor p53 by sequestration and additional mechanisms. Our present study revealed that the struggle between p53 and T-ag begins very early in the infection cycle. We found that p53 is activated early after SV40 infection and defends the host against the infection. Using live cell imaging and single cell analyses we found that p53 dynamics are variable among individual cells, with only a subset of cells activating p53 immediately after SV40 infection. This cell-to-cell variabilty had clear consequences on the outcome of the infection. None of the cells with elevated p53 at the beginning of the infection proceeded to express T-ag, suggesting a p53-dependent decision between abortive and productive infection. In addition, we show that artificial elevation of p53 levels prior to the infection reduces infection efficiency, supporting a role for p53 in defending against SV40. We further found that the p53-mediated host defense mechanism against SV40 is not facilitated by apoptosis nor via interferon-stimulated genes. Instead p53 binds to the viral DNA at the T-ag promoter region, prevents its transcriptional activation by Sp1, and halts the progress of the infection. These findings shed new light on the long studied struggle between SV40 T-ag and p53, as developed during virus-host coevolution. Our studies indicate that the fate of SV40 infection is determined as soon as the viral DNA enters the nucleus, before the onset of viral gene expression. PMID:27462916
PML is a ROS sensor activating p53 upon oxidative stress

PubMed Central

Soilihi, Hassane

2017-01-01

Promyelocytic leukemia (PML) nuclear bodies (NBs) recruit partner proteins, including p53 and its regulators, thereby controlling their abundance or function. Investigating arsenic sensitivity of acute promyelocytic leukemia, we proposed that PML oxidation promotes NB biogenesis. However, physiological links between PML and oxidative stress response in vivo remain unexplored. Here, we identify PML as a reactive oxygen species (ROS) sensor. Pml−/− cells accumulate ROS, whereas PML expression decreases ROS levels. Unexpectedly, Pml−/− embryos survive acute glutathione depletion. Moreover, Pml−/− animals are resistant to acetaminophen hepatotoxicity or fasting-induced steatosis. Molecularly, Pml−/− animals fail to properly activate oxidative stress–responsive p53 targets, whereas the NRF2 response is amplified and accelerated. Finally, in an oxidative stress–prone background, Pml−/− animals display a longevity phenotype, likely reflecting decreased basal p53 activation. Thus, similar to p53, PML exerts basal antioxidant properties but also drives oxidative stress–induced changes in cell survival/proliferation or metabolism in vivo. Through NB biogenesis, PML therefore couples ROS sensing to p53 responses, shedding a new light on the role of PML in senescence or stem cell biology. PMID:28931625
PML is a ROS sensor activating p53 upon oxidative stress.

PubMed

Niwa-Kawakita, Michiko; Ferhi, Omar; Soilihi, Hassane; Le Bras, Morgane; Lallemand-Breitenbach, Valérie; de Thé, Hugues

2017-11-06

Promyelocytic leukemia (PML) nuclear bodies (NBs) recruit partner proteins, including p53 and its regulators, thereby controlling their abundance or function. Investigating arsenic sensitivity of acute promyelocytic leukemia, we proposed that PML oxidation promotes NB biogenesis. However, physiological links between PML and oxidative stress response in vivo remain unexplored. Here, we identify PML as a reactive oxygen species (ROS) sensor. Pml -/- cells accumulate ROS, whereas PML expression decreases ROS levels. Unexpectedly, Pml -/- embryos survive acute glutathione depletion. Moreover, Pml -/- animals are resistant to acetaminophen hepatotoxicity or fasting-induced steatosis. Molecularly, Pml -/- animals fail to properly activate oxidative stress-responsive p53 targets, whereas the NRF2 response is amplified and accelerated. Finally, in an oxidative stress-prone background, Pml -/- animals display a longevity phenotype, likely reflecting decreased basal p53 activation. Thus, similar to p53, PML exerts basal antioxidant properties but also drives oxidative stress-induced changes in cell survival/proliferation or metabolism in vivo. Through NB biogenesis, PML therefore couples ROS sensing to p53 responses, shedding a new light on the role of PML in senescence or stem cell biology. © 2017 Niwa-Kawakita et al.
Characterization of the cellular and antitumor effects of MPI-0479605, a small-molecule inhibitor of the mitotic kinase Mps1.

PubMed

Tardif, Keith D; Rogers, Aaron; Cassiano, Jared; Roth, Bruce L; Cimbora, Daniel M; McKinnon, Rena; Peterson, Ashley; Douce, Thomas B; Robinson, Rosann; Dorweiler, Irene; Davis, Thaylon; Hess, Mark A; Ostanin, Kirill; Papac, Damon I; Baichwal, Vijay; McAlexander, Ian; Willardsen, J Adam; Saunders, Michael; Christophe, Hoarau; Kumar, D Vijay; Wettstein, Daniel A; Carlson, Robert O; Williams, Brandi L

2011-12-01

Mps1 is a dual specificity protein kinase that is essential for the bipolar attachment of chromosomes to the mitotic spindle and for maintaining the spindle assembly checkpoint until all chromosomes are properly attached. Mps1 is expressed at high levels during mitosis and is abundantly expressed in cancer cells. Disruption of Mps1 function induces aneuploidy and cell death. We report the identification of MPI-0479605, a potent and selective ATP competitive inhibitor of Mps1. Cells treated with MPI-0479605 undergo aberrant mitosis, resulting in aneuploidy and formation of micronuclei. In cells with wild-type p53, this promotes the induction of a postmitotic checkpoint characterized by the ATM- and RAD3-related-dependent activation of the p53-p21 pathway. In both wild-type and p53 mutant cells lines, there is a growth arrest and inhibition of DNA synthesis. Subsequently, cells undergo mitotic catastrophe and/or an apoptotic response. In xenograft models, MPI-0479605 inhibits tumor growth, suggesting that drugs targeting Mps1 may have utility as novel cancer therapeutics.
Heterogeneity of p53 dependent genomic responses following ethanol exposure in a developmental mouse model of fetal alcohol spectrum disorder

PubMed Central

Mooney, Sandra M.; Middleton, Frank A.

2017-01-01

Prenatal ethanol exposure can produce structural and functional deficits in the brain and result in Fetal Alcohol Spectrum Disorder (FASD). In rodent models acute exposure to a high concentration of alcohol causes increased apoptosis in the developing brain. A single causal molecular switch that signals for this increase in apoptosis has yet to be identified. The protein p53 has been suggested to play a pivotal role in enabling cells to engage in pro-apoptotic processes, and thus figures prominently as a hub molecule in the intracellular cascade of responses elicited by alcohol exposure. In the present study we examined the effect of ethanol-induced cellular and molecular responses in primary somatosensory cortex (SI) and hippocampus of 7-day-old wild-type (WT) and p53-knockout (KO) mice. We quantified apoptosis by active caspase-3 immunohistochemistry and ApopTag™ labeling, then determined total RNA expression levels in laminae of SI and hippocampal subregions. Immunohistochemical results confirmed increased incidence of apoptotic cells in both regions in WT and KO mice following ethanol exposure. The lack of p53 was not protective in these brain regions. Molecular analyses revealed a heterogeneous response to ethanol exposure that varied depending on the subregion, and which may go undetected using a global approach. Gene network analyses suggest that the presence or absence of p53 alters neuronal function and synaptic modifications following ethanol exposure, in addition to playing a classic role in cell cycle signaling. Thus, p53 may function in a way that underlies the intellectual and behavioral deficits observed in FASD. PMID:28723918
Expression of survivin and p53 in oral lichen planus, lichenoid reaction and lichenoid dysplasia: An immunohistochemical study

PubMed Central

Basheer, Shaini; Shameena, PM; Sudha, S; Varma, Sujatha; Vidyanath, S; Varekar, Aniruddha

2017-01-01

Context: The malignant transformation potential of oral lichen planus (OLP) and related lesions is a subject of great controversy. Aim: The aim of this study was to compare the expression of proteins related to apoptosis and tumour suppressor gene processes in OLP, oral lichenoid reaction (OLR) and oral lichenoid dysplasia (OLD). Materials and Methods The immunohistochemical study was carried out to investigate the expressions of survivin and p53 in a total of 30 lesional biopsy specimens - 10 cases each of OLP, OLR and OLD. The expression rates were further compared with 10 control specimens of normal oral mucosa (NORM). Results: Immunoreactivity for p53 was seen in 7 cases (70%) of OLD, 4 cases (40%) of OLP and 2 cases (20%) of OLR and none of NORM. We obtained a significant difference (P = 0.01) in mean p53 expression between the different entities. The positive staining rate of survivin was found to be significantly different between OLD (50%), OLP (10%), OLR (0%), and normal mucosa (0%) (P = 0.004). There was a positive correlation between p53 and survivin expression in OLP and OLD using Pearson's correlation coefficient. Conclusion: Lichenoid dysplasia has shown p53 and survivin expression in the range of not OLP, but leukoplakia. On the other hand, OLR seems to be an innocuous lesion. The study results with OLP are inconclusive but points toward a small but important malignant potential in OLP. This kind of comparative study highlights the importance of biopsying OLP and related lesions for proper diagnosis and appropriate management. PMID:29391729
p53-mediated inhibition of angiogenesis through up-regulation of a collagen prolyl hydroxylase.

PubMed

Teodoro, Jose G; Parker, Albert E; Zhu, Xiaochun; Green, Michael R

2006-08-18

Recent evidence suggests that antiangiogenic therapy is sensitive to p53 status in tumors, implicating a role for p53 in the regulation of angiogenesis. Here we show that p53 transcriptionally activates the alpha(II) collagen prolyl-4-hydroxylase [alpha(II)PH] gene, resulting in the extracellular release of antiangiogenic fragments of collagen type 4 and 18. Conditioned media from cells ectopically expressing either p53 or alpha(II)PH selectively inhibited growth of primary human endothelial cells. When expressed intracellularly or exogenously delivered, alpha(II)PH significantly inhibited tumor growth in mice. Our results reveal a genetic and biochemical linkage between the p53 tumor suppressor pathway and the synthesis of antiangiogenic collagen fragments.
Improved bioavailability of targeted Curcumin delivery efficiently regressed cardiac hypertrophy by modulating apoptotic load within cardiac microenvironment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, Aramita, E-mail: aramitaray@yahoo.co.in; Rana, Santanu, E-mail: rana.santanu@gmail.com; Banerjee, Durba, E-mail: durba.research@gmail.com

Cardiomyocyte apoptosis acts as a prime modulator of cardiac hypertrophy leading to heart failure, a major cause of human mortality worldwide. Recent therapeutic interventions have focussed on translational applications of diverse pharmaceutical regimes among which, Curcumin (from Curcuma longa) is known to have an anti-hypertrophic potential but with limited pharmacological efficacies due to low aqueous solubility and poor bioavailability. In this study, Curcumin encapsulated by carboxymethyl chitosan (CMC) nanoparticle conjugated to a myocyte specific homing peptide was successfully delivered in bioactive form to pathological myocardium for effective regression of cardiac hypertrophy in a rat (Rattus norvegicus) model. Targeted nanotization showedmore » higher cardiac bioavailability of Curcumin at a low dose of 5 mg/kg body weight compared to free Curcumin at 35 mg/kg body weight. Moreover, Curcumin/CMC-peptide treatment during hypertrophy significantly improved cardiac function by downregulating expression of hypertrophy marker genes (ANF, β-MHC), apoptotic mediators (Bax, Cytochrome-c) and activity of apoptotic markers (Caspase 3 and PARP); whereas free Curcumin in much higher dose showed minimal improvement during compromised cardiac function. Targeted Curcumin treatment significantly lowered p53 expression and activation in diseased myocardium via inhibited interaction of p53 with p300-HAT. Thus attenuated acetylation of p53 facilitated p53 ubiquitination and reduced the apoptotic load in hypertrophied cardiomyocytes; thereby limiting cardiomyocytes' need to enter the regeneration cycle during hypertrophy. This study elucidates for the first time an efficient targeted delivery regimen for Curcumin and also attributes towards probable mechanistic insight into its therapeutic potential as a cardio-protective agent for regression of cardiac hypertrophy. - Highlights: • Cardiomyocyte targeted Curcumin/CMC-peptide increases bioavailability of the drug. • Curcumin nanoparticle regresses cardiac hypertrophy by reducing myocyte apoptosis. • Targeted Curcumin shows higher efficacy over free Curcumin to regress hypertrophy. • Curcumin modulates p300-HAT axis to facilitate p53 degradation.« less
H2O2 accelerates cellular senescence by accumulation of acetylated p53 via decrease in the function of SIRT1 by NAD+ depletion.

PubMed

Furukawa, Ayako; Tada-Oikawa, Saeko; Kawanishi, Shosuke; Oikawa, Shinji

2007-01-01

It has been reported that p53 acetylation, which promotes cellular senescence, can be regulated by the NAD(+)-dependent deacetylase SIRT1, the human homolog of yeast Sir2, a protein that modulates lifespan. To clarify the role of SIRT1 in cellular senescence induced by oxidative stress, we treated normal human diploid fibroblast TIG-3 cells with H(2)O(2) and examined DNA cleavage, depletion of intracellular NAD(+), expression of p21, SIRT1, and acetylated p53, cell cycle arrest, and senescence-associated beta-galactosidase (SA-beta-gal) activity. DNA cleavage was observed immediately in TIG-3 cells treated with H(2)O(2), though no cell death was observed. NAD(+) levels in TIG-3 cells treated with H(2)O(2) were also decreased significantly. Pre-incubation with the poly (ADP-ribose) polymerase (PARP) inhibitor resulted in preservation of intracellular NAD(+) levels. The amount of acetylated p53 was increased in TIG-3 cells at 4h after H(2)O(2) treatment, while there was little to no decrease in SIRT1 protein expression. The expression level of p21 was increased at 12h and continued to increase for up to 24h. Additionally, exposure of TIG-3 cells to H(2)O(2) induced cell cycle arrest at 24h and increased SA-beta-gal activity at 48h. This pathway likely plays an important role in the acceleration of cellular senescence by oxidative stress.
Human papillomavirus oncogenic E6 protein regulates human β-defensin 3 (hBD3) expression via the tumor suppressor protein p53

PubMed Central

Yue, Hong; Wang, Liming; Jin, Jessica; Ghosh, Santosh K.; Kawsar, Hameem I.; Zender, Chad; Androphy, Elliot J.; Weinberg, Aaron; McCormick, Thomas S.; Jin, Ge

2016-01-01

Human β-defensin-3 (hBD3) is an epithelial cell-derived innate immune regulatory molecule overexpressed in oral dysplastic lesions and fosters a tumor-promoting microenvironment. Expression of hBD3 is induced by the epidermal growth factor receptor signaling pathway. Here we describe a novel pathway through which the high-risk human papillomavirus type-16 (HPV-16) oncoprotein E6 induces hBD3 expression in mucosal keratinocytes. Ablation of E6 by siRNA induces the tumor suppressor p53 and diminishes hBD3 in HPV-16 positive CaSki cervical cancer cells and UM-SCC-104 head and neck cancer cells. Malignant cells in HPV-16-associated oropharyngeal cancer overexpress hBD3. HPV-16 E6 induces hBD3 mRNA expression, peptide production and gene promoter activity in mucosal keratinocytes. Reduction of cellular levels of p53 stimulates hBD3 expression, while activation of p53 by doxorubicin inhibits its expression in primary oral keratinocytes and CaSki cells, suggesting that p53 represses hBD3 expression. A p53 binding site in the hBD3 gene promoter has been identified by using electrophoretic mobility shift assays and chromatin immunoprecipitation (ChIP). In addition, the p63 protein isoform ΔNp63α, but not TAp63, stimulated transactivation of the hBD3 gene and was co-expressed with hBD3 in head and neck cancer specimens. Therefore, high-risk HPV E6 oncoproteins may stimulate hBD3 expression in tumor cells to facilitate tumorigenesis of HPV-associated head and neck cancer. PMID:27034006
Inhibition of maternal embryonic leucine zipper kinase with OTSSP167 displays potent anti-leukemic effects in chronic lymphocytic leukemia.

PubMed

Zhang, Ya; Zhou, Xiangxiang; Li, Ying; Xu, Yangyang; Lu, Kang; Li, Peipei; Wang, Xin

2018-06-12

TP53 pathway defects contributed to therapy resistance and adverse clinical outcome in chronic lymphocytic leukemia (CLL), which represents an unmet clinical need with few therapeutic options. Maternal embryonic leucine zipper kinase (MELK) is a novel oncogene, which plays crucial roles in mitotic progression and stem cell maintenance. OTSSP167, an orally administrated inhibitor targeting MELK, is currently in a phase I/II clinical trial in patients with advanced breast cancer and acute myeloid leukemia. Yet, no investigation has been elucidated to date regarding the oncogenic role of MELK and effects of OTSSP167 in chronic lymphocytic leukemia (CLL). Previous studies confirmed MELK inhibition abrogated cancer cell survival via p53 signaling pathway. Thus, we aimed to determine the biological function of MELK and therapeutic potential of OTSSP167 in CLL. Herein, MELK over-expression was observed in CLL cells, and correlated with higher WBC count, advanced stage, elevated LDH, increased β2-MG level, unmutated IGHV, positive ZAP-70, deletion of 17p13 and inferior prognosis of CLL patients. In accordance with functional enrichment analyses in gene expression profiling, CLL cells with depletion or inhibition of MELK exhibited impaired cell proliferation, enhanced fast-onset apoptosis, induced G2/M arrest, attenuated cell chemotaxis and promoted sensitivity to fludarabine and ibrutinib. However, gain-of-function assay showed increased cell proliferation and cell chemotaxis. In addition, OTSSP167 treatment reduced phosphorylation of AKT and ERK1/2. It decreased FoxM1 phosphorylation, expression of FoxM1, cyclin B1 and CDK1, while up-regulating p53 and p21 expression. Taken together, MELK served as a candidate of therapeutic target in CLL. OTSSP167 exhibits potent anti-tumor activities in CLL cells, highlighting a novel molecule-based strategy for leukemic interventions.
Glucocorticoid regulation of a novel HPV-E6-p53-miR-145 pathway modulates invasion and therapy resistance of cervical cancer cells.

PubMed

Shi, Ming; Du, Libin; Liu, Dan; Qian, Lu; Hu, Meiru; Yu, Ming; Yang, Zhengyan; Zhao, Mingzhen; Chen, Changguo; Guo, Liang; Wang, Lina; Song, Lun; Ma, Yuanfang; Guo, Ning

2012-10-01

Glucocorticoids are stress-responsive neuroendocrine mediators and play an important role in malignant progression, especially in solid tumours. We demonstrate a novel mechanism by which glucocorticoids modulate p53-dependent miR-145 expression in HPV-positive cervical cancer cells through induction of E6 proteins. We found that expression of miR-145 was reduced in cervical cancer tissues. Cortisol induced HPV-E6 expression and suppressed p53 and miR-145 in cervical cancer cells. MiR-145 expression in cervical cancer cells was wild-type p53-dependent, and cortisol-induced down-regulation of miR-145 expression prevented chemotherapy-induced apoptosis, whereas over-expression of miR-145 enhanced sensitivity to mitomycin and reversed the chemoresistance induced by glucocorticoids. We also show that miR-145 augments the effects of p53 by suppressing the inhibitors of p53 in cervical cancer cells, suggesting that miR-145 plays a role in p53 tumour suppression. Finally, we demonstrate that miR-145 inhibits both the motility and invasion of cervical cancer cells. Our findings identify a novel pathway through which the neuroendocrine macroenvironment affects cervical tumour growth, invasion and therapy resistance and show that miR-145 may serve as a target for cervical cancer therapy. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Graphene Functionalized with Arginine Decreases the Development of Glioblastoma Multiforme Tumor in a Gene-Dependent Manner

PubMed Central

Sawosz, Ewa; Jaworski, Sławomir; Kutwin, Marta; Vadalasetty, Krishna Prasad; Grodzik, Marta; Wierzbicki, Mateusz; Kurantowicz, Natalia; Strojny, Barbara; Hotowy, Anna; Lipińska, Ludwika; Jagiełło, Joanna; Chwalibog, André

2015-01-01

Our previous studies revealed that graphene had anticancer properties in experiments in vitro with glioblastoma multiforme (GBM) cells and in tumors cultured in vivo. We hypothesized that the addition of arginine or proline to graphene solutions might counteract graphene agglomeration and increase the activity of graphene. Experiments were performed in vitro with GBM U87 cells and in vivo with GBM tumors cultured on chicken embryo chorioallantoic membranes. The measurements included cell morphology, mortality, viability, tumor morphology, histology, and gene expression. The cells and tumors were treated with reduced graphene oxide (rGO) and rGO functionalized with arginine (rGO + Arg) or proline (rGO + Pro). The results confirmed the anticancer effect of graphene on GBM cells and tumor tissue. After functionalization with amino acids, nanoparticles were distributed more specifically, and the flakes of graphene were less agglomerated. The molecule of rGO + Arg did not increase the expression of TP53 in comparison to rGO, but did not increase the expression of MDM2 or the MDM2/TP53 ratio in the tumor, suggesting that arginine may block MDM2 expression. The expression of NQO1, known to be a strong protector of p53 protein in tumor tissue, was greatly increased. The results indicate that the complex of rGO + Arg has potential in GBM therapy. PMID:26512645
Mechanism of p53-Dependent Apoptosis and its Role in Breast Cancer Therapy

DTIC Science & Technology

1999-07-01

inducibly express p53 as previously described (Chen et a!., 1996). ( a ) Levels of p53, p21, and actin in p53-3, and p53(A62-91)-l, -5, and -6 cells...1994) was used as template, ( a ) Levels of p53, p21 and actin in p53-3 and p53(gln22-ser23/A62-91)-2 and -14 cells were assayed by Western blot...CGG TAC CCC TGT CAT CTT CTG TC; and reverse primer C393 as used for generating p53(A62-91). ( a ) Levels of p53, p21, and actin in p53-3, and p53(A74
MicroRNA-145 is regulated by DNA methylation and p53 gene mutation in prostate cancer

PubMed Central

Suh, Seong O.; Chen, Yi; Zaman, Mohd Saif; Hirata, Hiroshi; Yamamura, Soichiro; Shahryari, Varahram; Liu, Jan; Tabatabai, Z.Laura; Kakar, Sanjay; Deng, Guoren; Tanaka, Yuichiro; Dahiya, Rajvir

2011-01-01

MiR-145 is downregulated in various cancers including prostate cancer. However, the underlying mechanisms of miR-145 downregulation are not fully understood. Here, we reported that miR-145 was silenced through DNA hypermethylation and p53 mutation status in laser capture microdissected (LCM) prostate cancer and matched adjacent normal tissues. In 22 of 27 (81%) prostate tissues, miR-145 was significantly downregulated in the cancer compared with the normal tissues. Further studies on miR-145 downregulation mechanism showed that miR-145 is methylated at the promoter region in both prostate cancer tissues and 50 different types of cancer cell lines. In seven cancer cell lines with miR-145 hypermethylation, 5-aza-2′-deoxycytidine treatment dramatically induced miR-145 expression. Interestingly, we also found a significant correlation between miR-145 expression and the status of p53 gene in both LCM prostate tissues and 47 cancer cell lines. In 29 cell lines with mutant p53, miR-145 levels were downregulated in 28 lines (97%), whereas in 18 cell lines with wild-type p53 (WT p53), miR-145 levels were downregulated in only 6 lines (33%, P < 0.001). Electrophoretic mobility shift assay showed that p53 binds to the p53 response element upstream of miR-145, but the binding was inhibited by hypermethylation. To further confirm that p53 binding to miR-145 could regulate miR-145 expression, we transfected WT p53 and MUT p53 into PC-3 cells and found that miR-145 is upregulated by WT p53 but not with MUTp53. The apoptotic cells are increased after WT p53 transfection. In summary, this is the first report documenting that downregulation of miR-145 is through DNA methylation and p53 mutation pathways in prostate cancer. PMID:21349819
Expression of AID, P53, and Mlh1 proteins in endoscopically resected differentiated-type early gastric cancer

PubMed Central

Takeda, Yohei; Yashima, Kazuo; Hayashi, Akihiro; Sasaki, Shuji; Kawaguchi, Koichiro; Harada, Kenichi; Murawaki, Yoshikazu; Ito, Hisao

2012-01-01

AIM: To analyze the expression of the tumor-related proteins in differentiated-type early gastric carcinoma (DEGC) samples. METHODS: Tumor specimens were obtained from 102 patients (75 males and 27 females) who had received an endoscopic tumor resection at Tottori University Hospital between 2007 and 2009. Ninety-one cancer samples corresponded to noninvasive or intramucosal carcinoma according to the Vienna classification system, and 11 samples were submucosal invasive carcinomas. All of the EGCs were histologically differentiated carcinomas. All patients were classified as having Helicobacter pylori (H. pylori) infections by endoscopic atrophic changes or by testing seropositive for H. pylori IgG. All of the samples were histopathologically classified as either tubular or papillary adenocarcinoma according to their structure. The immunohistochemical staining was performed in a blinded manner with respect to the clinical information. Two independent observers evaluated protein expression. All data were statistically analyzed then. RESULTS: The rates of aberrant activation-induced cytidine deaminase (AID) expression and P53 overexpression were both 34.3% in DEGCs. The expression of Mlh1 was lost in 18.6% of DEGCs. Aberrant AID expression was not significantly associated with P53 overexpression in DEGCs. However, AID expression was associated with the severity of mononuclear cell activity in the non-cancerous mucosa adjacent to the tumor (P = 0.064). The rate of P53 expression was significantly greater in flat or depressed tumors than in elevated tumors. The frequency of Mlh1 loss was significantly increased in distal tumors, elevated gross-type tumors, papillary histological-type tumors, and tumors with a severe degree of endoscopic atrophic gastritis (P < 0.05). CONCLUSION: Aberrant AID expression, P53 overexpression, and the loss of Mlh1 were all associated with clinicopathological features and gastric mucosal alterations in DEGCs. The aberrant expression of AID protein may partly contribute to the induction of nuclear P53 expression. PMID:22737274
Inhibitory effect of Survivin promoter-regulated oncolytic adenovirus carrying P53 gene against gallbladder cancer.

PubMed

Liu, Chen; Sun, Bin; An, Ni; Tan, Weifeng; Cao, Lu; Luo, Xiangji; Yu, Yong; Feng, Feiling; Li, Bin; Wu, Mengchao; Su, Changqing; Jiang, Xiaoqing

2011-12-01

Gene therapy has become an important strategy for treatment of malignancies, but problems remains concerning the low gene transferring efficiency, poor transgene expression and limited targeting specific tumors, which have greatly hampered the clinical application of tumor gene therapy. Gallbladder cancer is characterized by rapid progress, poor prognosis, and aberrantly high expression of Survivin. In the present study, we used a human tumor-specific Survivin promoter-regulated oncolytic adenovirus vector carrying P53 gene, whose anti-cancer effect has been widely confirmed, to construct a wide spectrum, specific, safe, effective gene-viral therapy system, AdSurp-P53. Examining expression of enhanced green fluorecent protein (EGFP), E1A and the target gene P53 in the oncolytic adenovirus system validated that Survivin promoter-regulated oncolytic adenovirus had high proliferation activity and high P53 expression in Survivin-positive gallbladder cancer cells. Our in vitro cytotoxicity experiment demonstrated that AdSurp-P53 possessed a stronger cytotoxic effect against gallbladder cancer cells and hepatic cancer cells. The survival rate of EH-GB1 cells was lower than 40% after infection of AdSurp-P53 at multiplicity of infection (MOI) = 1 pfu/cell, while the rate was higher than 90% after infection of Ad-P53 at the same MOI, demonstrating that AdSurp-P53 has a potent cytotoxicity against EH-GB1 cells. The tumor growth was greatly inhibited in nude mice bearing EH-GB1 xenografts when the total dose of AdSurp-P53 was 1 × 10(9) pfu, and terminal dUTP nick end-labeling (TUNEL) revealed that the apoptotic rate of cancer cells was (33.4 ± 8.4)%. This oncolytic adenovirus system overcomes the long-standing shortcomings of gene therapy: poor transgene expression and targeting of only specific tumors, with its therapeutic effect better than the traditional Ad-P53 therapy regimen already on market; our system might be used for patients with advanced gallbladder cancer and other cancers, who are not sensitive to chemotherapy, radiotherapy, or who lost their chance for surgical treatment. Copyright © 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Using a preclinical mouse model of high-grade astrocytoma to optimize p53 restoration therapy.

PubMed

Shchors, Ksenya; Persson, Anders I; Rostker, Fanya; Tihan, Tarik; Lyubynska, Natalya; Li, Nan; Swigart, Lamorna Brown; Berger, Mitchel S; Hanahan, Douglas; Weiss, William A; Evan, Gerard I

2013-04-16

Based on clinical presentation, glioblastoma (GBM) is stratified into primary and secondary types. The protein 53 (p53) pathway is functionally incapacitated in most GBMs by distinctive type-specific mechanisms. To model human gliomagenesis, we used a GFAP-HRas(V12) mouse model crossed into the p53ER(TAM) background, such that either one or both copies of endogenous p53 is replaced by a conditional p53ER(TAM) allele. The p53ER(TAM) protein can be toggled reversibly in vivo between wild-type and inactive conformations by administration or withdrawal of 4-hydroxytamoxifen (4-OHT), respectively. Surprisingly, gliomas that develop in GFAP-HRas(V12);p53(+/KI) mice abrogate the p53 pathway by mutating p19(ARF)/MDM2 while retaining wild-type p53 allele. Consequently, such tumors are unaffected by restoration of their p53ER(TAM) allele. By contrast, gliomas arising in GFAP-HRas(V12);p53(KI/KI) mice develop in the absence of functional p53. Such tumors retain a functional p19(ARF)/MDM2-signaling pathway, and restoration of p53ER(TAM) allele triggers p53-tumor-suppressor activity. Congruently, growth inhibition upon normalization of mutant p53 by a small molecule, Prima-1, in human GBM cultures also requires p14(ARF)/MDM2 functionality. Notably, the antitumoral efficacy of p53 restoration in tumor-bearing GFAP-HRas(V12);p53(KI/KI) animals depends on the duration and frequency of p53 restoration. Thus, intermittent exposure to p53ER(TAM) activity mitigated the selective pressure to inactivate the p19(ARF)/MDM2/p53 pathway as a means of resistance, extending progression-free survival. Our results suggest that intermittent dosing regimes of drugs that restore wild-type tumor-suppressor function onto mutant, inactive p53 proteins will prove to be more efficacious than traditional chronic dosing by similarly reducing adaptive resistance.
Using a preclinical mouse model of high-grade astrocytoma to optimize p53 restoration therapy

PubMed Central

Shchors, Ksenya; Persson, Anders I.; Rostker, Fanya; Tihan, Tarik; Lyubynska, Natalya; Li, Nan; Swigart, Lamorna Brown; Berger, Mitchel S.; Hanahan, Douglas; Weiss, William A.; Evan, Gerard I.

2013-01-01

Based on clinical presentation, glioblastoma (GBM) is stratified into primary and secondary types. The protein 53 (p53) pathway is functionally incapacitated in most GBMs by distinctive type-specific mechanisms. To model human gliomagenesis, we used a GFAP-HRasV12 mouse model crossed into the p53ERTAM background, such that either one or both copies of endogenous p53 is replaced by a conditional p53ERTAM allele. The p53ERTAM protein can be toggled reversibly in vivo between wild-type and inactive conformations by administration or withdrawal of 4-hydroxytamoxifen (4-OHT), respectively. Surprisingly, gliomas that develop in GFAP-HRasV12;p53+/KI mice abrogate the p53 pathway by mutating p19ARF/MDM2 while retaining wild-type p53 allele. Consequently, such tumors are unaffected by restoration of their p53ERTAM allele. By contrast, gliomas arising in GFAP-HRasV12;p53KI/KI mice develop in the absence of functional p53. Such tumors retain a functional p19ARF/MDM2-signaling pathway, and restoration of p53ERTAM allele triggers p53-tumor–suppressor activity. Congruently, growth inhibition upon normalization of mutant p53 by a small molecule, Prima-1, in human GBM cultures also requires p14ARF/MDM2 functionality. Notably, the antitumoral efficacy of p53 restoration in tumor-bearing GFAP-HRasV12;p53KI/KI animals depends on the duration and frequency of p53 restoration. Thus, intermittent exposure to p53ERTAM activity mitigated the selective pressure to inactivate the p19ARF/MDM2/p53 pathway as a means of resistance, extending progression-free survival. Our results suggest that intermittent dosing regimes of drugs that restore wild-type tumor-suppressor function onto mutant, inactive p53 proteins will prove to be more efficacious than traditional chronic dosing by similarly reducing adaptive resistance. PMID:23542378

Histone demethylase JMJD2B is required for tumor cell proliferation and survival and is overexpressed in gastric cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wenjuan; Zhao, Li; Zang, Wen

2011-12-16

Highlights: Black-Right-Pointing-Pointer JMJD2B is required for cell proliferation and in vivo tumorigenesis. Black-Right-Pointing-Pointer JMJD2B depletion induces apoptosis and/or cell cycle arrest. Black-Right-Pointing-Pointer JMJD2B depletion activates DNA damage response and enhances p53 stabilization. Black-Right-Pointing-Pointer JMJD2B is overexpressed in human primary gastric cancer. -- Abstract: Epigenetic alterations such as aberrant expression of histone-modifying enzymes have been implicated in tumorigenesis. Jumonji domain containing 2B (JMJD2B) is a newly identified histone demethylase that regulates chromatin structure or gene expression by removing methyl residues from trimethylated lysine 9 on histone H3. Recent observations have shown oncogenic activity of JMJD2B. We explored the functional role ofmore » JMJD2B in cancer cell proliferation, survival and tumorigenesis, and determined its expression profile in gastric cancer. Knocking down JMJD2B expression by small interfering RNA (siRNA) in gastric and other cancer cells inhibited cell proliferation and/or induced apoptosis and elevated the expression of p53 and p21{sup CIP1} proteins. The enhanced p53 expression resulted from activation of the DNA damage response pathway. JMJD2B knockdown markedly suppressed xenograft tumor growth in vivo in mice. Moreover, JMJD2B expression was increased in primary gastric-cancer tissues of humans. Thus, JMJD2B is required for sustained proliferation and survival of tumor cells in vitro and in vivo, and its aberrant expression may contribute to the pathogenesis of gastric cancer.« less
Apoptosis and cell proliferation in the development of gastric carcinomas: associations with c-myc and p53 protein expression.

PubMed

Ishii, Hideaki H; Gobé, Glenda C; Pan, Wenshen; Yoneyama, Juichi; Ebihara, Yoshiro

2002-09-01

Patients with gastric carcinomas have a poor prognosis and low survival rates. The aim of the present paper was to characterize cellular and molecular properties to provide insight into aspects of tumor progression in early compared with advanced gastric cancers. One hundred and nine graded gastric carcinomas (early or advanced stage, undifferentiated or differentiated type) with paired non-cancer tissue were studied to define the correlation between apoptosis (morphology, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling), cell proliferation (Ki-67 expression, morphology) and expression and localization of two proteins frequently having altered expression in cancers, namely p53 and c-myc. Overall, apoptosis was lower in early stage, differentiated and undifferentiated gastric carcinomas compared with advanced-stage cancers. Cell proliferation was comparatively high in all stages. There was a high level of p53 positivity in all stages. Only the early- and advanced-stage undifferentiated cancers that were p53 positive had a significantly higher level of apoptosis (P < 0.05). Cell proliferation was significantly greater (P < 0.05) only in the early undifferentiated cancers that had either c-myc or p53-positivity. The results indicate that low apoptosis and high cell proliferation combine to drive gastric cancer development. The molecular controls for high cell proliferation of the early stage undifferentiated gastric cancers involve overexpression of both p53 and c-myc. Overexpression of p53 may also control cancer development in that its expression is associated with higher levels of apoptosis in early and late-stage undifferentiated, cancers. Copyright 2002 Blackwell Publishing Asia Pty Ltd
Chronic centrosome amplification without tumorigenesis

PubMed Central

Vitre, Benjamin; Holland, Andrew J.; Kulukian, Anita; Shoshani, Ofer; Hirai, Maretoshi; Wang, Yin; Maldonado, Marcus; Cho, Thomas; Boubaker, Jihane; Swing, Deborah A.; Tessarollo, Lino; Evans, Sylvia M.; Fuchs, Elaine; Cleveland, Don W.

2015-01-01

Centrosomes are microtubule-organizing centers that facilitate bipolar mitotic spindle assembly and chromosome segregation. Recognizing that centrosome amplification is a common feature of aneuploid cancer cells, we tested whether supernumerary centrosomes are sufficient to drive tumor development. To do this, we constructed and analyzed mice in which centrosome amplification can be induced by a Cre-recombinase–mediated increase in expression of Polo-like kinase 4 (Plk4). Elevated Plk4 in mouse fibroblasts produced supernumerary centrosomes and enhanced the expected mitotic errors, but proliferation continued only after inactivation of the p53 tumor suppressor. Increasing Plk4 levels in mice with functional p53 produced centrosome amplification in liver and skin, but this did not promote spontaneous tumor development in these tissues or enhance the growth of chemically induced skin tumors. In the absence of p53, Plk4 overexpression generated widespread centrosome amplification, but did not drive additional tumors or affect development of the fatal thymic lymphomas that arise in animals lacking p53. We conclude that, independent of p53 status, supernumerary centrosomes are not sufficient to drive tumor formation. PMID:26578792
Genetic networks lead and follow tumor development: microRNA regulation of cell cycle and apoptosis in the p53 pathways.

PubMed

Otsuka, Kurataka; Ochiya, Takahiro

2014-01-01

During the past ten years, microRNAs (miRNAs) have been shown to play a more significant role in the formation and progression of cancer diseases than previously thought. With an increase in reports about the dysregulation of miRNAs in diverse tumor types, it becomes more obvious that classic tumor-suppressive molecules enter deep into the world of miRNAs. Recently, it has been demonstrated that a typical tumor suppressor p53, known as the guardian of the genome, regulates some kinds of miRNAs to contribute to tumor suppression by the induction of cell-cycle arrest and apoptosis. Meanwhile, miRNAs directly/indirectly control the expression level and activity of p53 to fine-tune its functions or to render p53 inactive, indicating that the interplay between p53 and miRNA is overly complicated. The findings, along with current studies, will underline the continuing importance of understanding this interlocking control system for future therapeutic strategies in cancer treatment and prevention.
Genetic Networks Lead and Follow Tumor Development: MicroRNA Regulation of Cell Cycle and Apoptosis in the p53 Pathways

PubMed Central

Otsuka, Kurataka; Ochiya, Takahiro

2014-01-01

During the past ten years, microRNAs (miRNAs) have been shown to play a more significant role in the formation and progression of cancer diseases than previously thought. With an increase in reports about the dysregulation of miRNAs in diverse tumor types, it becomes more obvious that classic tumor-suppressive molecules enter deep into the world of miRNAs. Recently, it has been demonstrated that a typical tumor suppressor p53, known as the guardian of the genome, regulates some kinds of miRNAs to contribute to tumor suppression by the induction of cell-cycle arrest and apoptosis. Meanwhile, miRNAs directly/indirectly control the expression level and activity of p53 to fine-tune its functions or to render p53 inactive, indicating that the interplay between p53 and miRNA is overly complicated. The findings, along with current studies, will underline the continuing importance of understanding this interlocking control system for future therapeutic strategies in cancer treatment and prevention. PMID:25302307
Negative feedback regulation of wild-type p53 biosynthesis.

PubMed Central

Mosner, J; Mummenbrauer, T; Bauer, C; Sczakiel, G; Grosse, F; Deppert, W

1995-01-01

When growth-arrested mouse fibroblasts re-entered the cell-cycle, the rise in tumour suppressor p53 mRNA level markedly preceded the rise in expression of the p53 protein. Furthermore, gamma-irradiation of such cells led to a rapid increase in p53 protein biosynthesis even in the presence of the transcription inhibitor actinomycin D. Both findings strongly suggest that p53 biosynthesis in these cells is regulated at the translational level. We present evidence for an autoregulatory control of p53 expression by a negative feed-back loop: p53 mRNA has a predicted tendency to form a stable stem-loop structure that involves the 5'-untranslated region (5'-UTR) plus some 280 nucleotides of the coding sequence. p53 binds tightly to the 5'-UTR region and inhibits the translation of its own mRNA, most likely mediated by the p53-intrinsic RNA re-annealing activity. The inhibition of p53 biosynthesis requires wild-type p53, as it is not observed with MethA mutant p53, p53-catalysed translational inhibition is selective; it might be restricted to p53 mRNA and a few other mRNAs that are able to form extensive stem-loop structures. Release from negative feed-back regulation of p53 biosynthesis, e.g. after damage-induced nuclear transport of p53, might provide a means for rapidly increasing p53 protein levels when p53 is required to act as a cell-cycle checkpoint determinant after DNA damage. Images PMID:7556087
P53 Protein Expression in Dental Follicle, Dentigerous Cyst, Odontogenic Keratocyst, and Inflammatory Subtypes of Cysts: An Immunohistochemical Study

PubMed Central

Fatemeh, Mashhadiabbas; Sepideh, Arab; Sara, Bagheri Seyedeh; Nazanin, Mahdavi

2017-01-01

Objectives An odontogenic keratocyst (OKC) is a developmental odontogenic cyst with aggressive clinical behavior. This cyst shows a different growth mechanism from the more common dentigerous cyst and now has been renamed as a keratocystic odontogenic tumor (KCOT). Inflammation can assist tumor growth via different mechanisms including dysregulation of the p53 gene. This study aims to assess and compare the expression of tumor suppressor gene p53 in inflamed and non-inflamed types of OKC and dentigerous cyst. Methods Immunohistochemical expression of p53 was assessed in 14 cases of dental follicle, 34 cases of OKC (including 18 inflamed OKCs), and 31 cases of dentigerous cyst (including 16 inflamed cysts). Results The mean percentage of p53 positive cells was 0.7% in dental follicles, 5.4% in non-inflamed OKCs, 17.3% in inflamed OKCs, 1.2% in non-inflamed dentigerous cysts, and 2.2% in inflamed dentigerous cysts. The differences between the groups were statistically significant (p < 0.050) except for the difference between inflamed and non-inflamed dentigerous cysts, and between dental follicle and non-inflamed dentigerous cyst. Conclusions The difference in p53 expression in OKC and dentigerous cyst can explain their different growth mechanism and clinical behavior. Inflammation is responsible for the change in behavior of neoplastic epithelium of OKC via p53 overexpression. PMID:28584604
P53 Protein Expression in Dental Follicle, Dentigerous Cyst, Odontogenic Keratocyst, and Inflammatory Subtypes of Cysts: An Immunohistochemical Study.

PubMed

Fatemeh, Mashhadiabbas; Sepideh, Arab; Sara, Bagheri Seyedeh; Nazanin, Mahdavi

2017-05-01

An odontogenic keratocyst (OKC) is a developmental odontogenic cyst with aggressive clinical behavior. This cyst shows a different growth mechanism from the more common dentigerous cyst and now has been renamed as a keratocystic odontogenic tumor (KCOT). Inflammation can assist tumor growth via different mechanisms including dysregulation of the p53 gene. This study aims to assess and compare the expression of tumor suppressor gene p53 in inflamed and non-inflamed types of OKC and dentigerous cyst. Immunohistochemical expression of p53 was assessed in 14 cases of dental follicle, 34 cases of OKC (including 18 inflamed OKCs), and 31 cases of dentigerous cyst (including 16 inflamed cysts). The mean percentage of p53 positive cells was 0.7% in dental follicles, 5.4% in non-inflamed OKCs, 17.3% in inflamed OKCs, 1.2% in non-inflamed dentigerous cysts, and 2.2% in inflamed dentigerous cysts. The differences between the groups were statistically significant ( p < 0.050) except for the difference between inflamed and non-inflamed dentigerous cysts, and between dental follicle and non-inflamed dentigerous cyst. The difference in p53 expression in OKC and dentigerous cyst can explain their different growth mechanism and clinical behavior. Inflammation is responsible for the change in behavior of neoplastic epithelium of OKC via p53 overexpression.
Pathobiological implications of MUC4 in non-small-cell lung cancer.

PubMed

Majhi, Prabin Dhangada; Lakshmanan, Imayavaramban; Ponnusamy, Moorthy P; Jain, Maneesh; Das, Srustidhar; Kaur, Sukhwinder; Shimizu, Su Tomohiro; West, William W; Johansson, Sonny L; Smith, Lynette M; Yu, Fang; Rolle, Cleo E; Sharma, Poonam; Carey, George B; Batra, Surinder K; Ganti, Apar Kishor

2013-04-01

Altered expression of MUC4 plays an oncogenic role in various cancers, including pancreatic, ovarian, and breast. This study evaluates the expression and role of MUC4 in non-small-cell lung cancer (NSCLC). We used a paired system of MUC4-expressing (H292) and MUC4-nonexpressing (A549) NSCLC cell lines to analyze MUC4-dependent changes in growth rate, migration, and invasion using these sublines. We also evaluated the alterations of several tumor suppressor, proliferation, and metastasis markers with altered MUC4 expression. Furthermore, the association of MUC4 expression (by immunohistochemistry) in lung cancer samples with patient survival was evaluated. MUC4-expressing lung cancer cells demonstrated a less proliferative and metastatic phenotype. Up-regulation of p53 in MUC4-expressing lung cancer cells led to the accumulation of cells at the G2/M phase of cell cycle progression. MUC4 expression attenuated Akt activation and decreased the expression of Cyclins D1 and E, but increased the expression of p21 and p27. MUC4 expression abrogated cancer cell migration and invasion by altering N- & E-cadherin expression and FAK phosphorylation. A decrease in MUC4 expression was observed with increasing tumor stage (mean composite score: stage I, 2.4; stage II, 1.8; stage III, 1.4; and metastatic, 1.2; p = 0.0093). Maximal MUC4 expression was associated with a better overall survival (p = 0.042). MUC4 plays a tumor-suppressor role in NSCLC by altering p53 expression in NSCLC. Decrease in MUC4 expression in advanced tumor stages also seems to confirm the novel protective function of MUC4 in NSCLC.
MDM2 is an important prognostic and predictive factor for platin-pemetrexed therapy in malignant pleural mesotheliomas and deregulation of P14/ARF (encoded by CDKN2A) seems to contribute to an MDM2-driven inactivation of P53.

PubMed

Walter, R F H; Mairinger, F D; Ting, S; Vollbrecht, C; Mairinger, T; Theegarten, D; Christoph, D C; Schmid, K W; Wohlschlaeger, J

2015-03-03

Malignant pleural mesothelioma (MPM) is a highly aggressive tumour that is first-line treated with a combination of cisplatin and pemetrexed. Until now, predictive and prognostic biomarkers are lacking, making it a non-tailored therapy regimen with unknown outcome. P53 is frequently inactivated in MPM, but mutations are extremely rare. MDM2 and P14/ARF are upstream regulators of P53 that may contribute to P53 inactivation. A total of 72 MPM patients were investigated. MDM2 immunoexpression was assessed in 65 patients. MDM2 and P14/ARF mRNA expression was analysed in 48 patients of the overall collective. The expression results were correlated to overall survival (OS) and progression-free survival (PFS). OS and PFS correlated highly significantly with MDM2 mRNA and protein expression, showing a dismal prognosis for patients with elevated MDM2 expression (for OS: Score (logrank) test: P⩽0.002, and for PFS: Score (logrank) test; P<0.007). MDM2 was identified as robust prognostic and predictive biomarker for MPM on the mRNA and protein level. P14/ARF mRNA expression reached no statistical significance, but Kaplan-Meier curves distinguished patients with low P14/ARF expression and hence shorter survival from patients with higher expression and prolonged survival. MDM2 is a prognostic and predictive marker for a platin-pemetrexed therapy of patients with MPMs. Downregulation of P14/ARF expression seems to contribute to MDM2-overexpression-mediated P53 inactivation in MPM patients.
Wt-p53 action in human leukaemia cell lines corresponding to different stages of differentiation.

PubMed

Rizzo, M G; Zepparoni, A; Cristofanelli, B; Scardigli, R; Crescenzi, M; Blandino, G; Giuliacci, S; Ferrari, S; Soddu, S; Sacchi, A

1998-05-01

Recent studies support the potential application of the wt-p53 gene in cancer therapy. Expression of exogenous wt-p53 suppresses a variety of leukaemia phenotypes by acting on cell survival, proliferation and/or differentiation. As for tumour gene therapy, the final fate of the neoplastic cells is one of the most relevant points. We examined the effects of exogenous wt-p53 gene expression in several leukaemia cell lines to identify p53-responsive leukaemia. The temperature-sensitive p53Val135 mutant or the human wt-p53 cDNA was transduced in leukaemia cell lines representative of different acute leukaemia FAB subtypes, including M1 (KG1), M2 (HL-60), M3 (NB4), M5 (U937) and M6 (HEL 92.1.7), as well as blast crisis of chronic myelogenous leukaemia (BC-CML: K562, BV173) showing diverse differentiation features. By morphological, molecular and biochemical analyses, we have shown that exogenous wt-p53 gene expression induces apoptosis only in cells corresponding to M1, M2 and M3 of the FAB classification and in BC-CML showing morphological and cytochemical features of undifferentiated blast cells. In contrast, it promotes differentiation in the others. Interestingly, cell responsiveness was independent of the vector used and the status of the endogenous p53 gene.
Repression of the interleukin 6 gene promoter by p53 and the retinoblastoma susceptibility gene product

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santhanam, U.; Ray, A.; Sehgal, P.B.

1991-09-01

The aberrant overexpression of interleukin 6 (IL-6) is implicated as an autocrine mechanism in the enhanced proliferation of the neoplastic cell elements in various B- and T-cell malignancies and in some carcinomas and sarcomas; many of these neoplasms have been shown to be associated with a mutated p53 gene. The possibility that wild-type (wt) p53, a nuclear tumor-suppressor protein, but not its transforming mutants might serve to repress IL-6 gene expression was investigated in HeLa cells. The authors transiently cotransfected these cells with constitutive cytomegalovirus (CMV) enhancer/promoter expression plasmids overproducing wt or mutant human or murine p53 and with appropriatemore » chloramphenicol acetyltransferase (CAT) reporter plasmids containing the promoter elements of human IL-6, c-fos, or {beta}-actin genes or of porcine major histocompatibility complex (MHC) class I gene in pN-38 to evaluate the effect of the various p53 species on these promoters. These observations identify transcriptional repression as a property of p53 and suggest that p53 and RB may be involved as transcriptional repressors in modulating IL-6 gene expression during cellular differentiation and oncogenesis.« less
Overexpression of microRNA‑125a‑3p effectively inhibits the cell growth and invasion of lung cancer cells by regulating the mouse double minute 2 homolog/p53 signaling pathway.

PubMed

Li, Shenglei; Li, Xin; Zhao, Huasi; Gao, Ming; Wang, Feng; Li, Wencai

2015-10-01

MicroRNAs (miRs) are a family of small non-coding RNAs that are 21‑24 nucleotides in length. Decreased expression of hsa‑miR‑125a‑3p is observed in a number of patients with non‑small cell lung cancer; however, it is not clear how this miRNA regulates the growth and invasion of lung tumor cells. The aim of the present study was to identify the function of hsa‑miR‑125a‑3p in the growth and invasion of lung cancer cells. The expression of hsa‑miR‑125a‑3p in the A549, NCI‑H460 and SPCA‑1 lung cancer cell lines was analyzed by reverse transcription‑quantitative polymerase chain reaction and the human bronchiolar epithelium cell line (HBE) was used as a control. The results demonstrated that the expression of hsa‑miR‑125a‑3p was significantly lower in NCI‑H460, A549 and SPCA‑1 cells, compared with that in HBE cells. Overexpression of sense miR‑125a‑3p in the A549 lung cancer cell line inhibited cell proliferation for 5‑7 days (P<0.01), and transfection of antisense miR‑125a‑3p did not suppress the cell growth of the lung cancer cells. In addition, overexpression of miR‑125a‑3p in the NCI‑H460 lung cancer cell line markedly induced cell apoptosis, which was detected by fluorescence‑activated cell sorting with annexin V‑fluorescein isothiocyanate/propidium iodide staining. The results of the Transwell migration assay also revealed that transfection of miR‑125a‑3p resulted in decreased migration of lung cancer tumor cells. The pro‑apoptotic gene p53 expression was detected by western blot analysis. The results revealed that the expression of mouse double minute (MDM)‑2 homolog, the principal cellular antagonist of p53, was decreased and p53 expression was upregulated in sense has‑miR‑125a‑3p transfected A549 cells. This was consistent with that observed in NCI‑H460 cells, suggesting that hsa‑miR‑125a‑3p may be involved in the regulation of the MDM2/p53 signaling pathway in lung cancer cells. In conclusion, overexpression of hsa‑miR‑125a‑3p significantly inhibited the proliferation and invasion of lung cancer cells, which may aid in determining the mechanisms underlying the development of lung cancer.
Modulation of the intestinal environment, innate immune response, and barrier function by dietary threonine and purified fiber during a coccidiosis challenge in broiler chicks.

PubMed

Wils-Plotz, E L; Jenkins, M C; Dilger, R N

2013-03-01

Coccidiosis is a major contributor to economic losses in the poultry industry due to its detrimental effects on growth performance and nutrient utilization. We hypothesized that the combined effects of supplemental dietary Thr and purified fiber may modulate the intestinal environment and positively affect intestinal immune responses and barrier function in broiler chicks infected with Eimeria maxima. A Thr-deficient basal diet (3.1 g of Thr/kg of diet) was supplemented with 70 g/kg of silica sand (control) or high-methoxy pectin and 1 of 2 concentrations of Thr (1.8 or 5.3 g/kg of diet; 4 diets total), and fed to chicks from hatch to d 16 posthatch. On d 10 posthatch, chicks received 0.5 mL of distilled water or an acute dose of Eimeria maxima (1.5 × 10(3) sporulated oocytes) with 6 replicate pens of 6 chicks per each of 8 treatment combinations (4 diets and 2 inoculation states). Body weight gain, feed intake, and G:F increased (P < 0.01) with addition of 5.3 g of Thr/kg of diet. Eimeria maxima schizonts were present only in intestinal tissue sampled from infected birds (P < 0.01). Weights of cecal digesta were highest (P < 0.01) in pectin-fed birds, and ceca with the heaviest weights also had the highest concentrations of total short-chain fatty acids. Expression of interleukin-12 in ileal mucosa was highest (P < 0.01) in infected birds receiving the control diet with 5.3 g of supplemental Thr/kg. In cecal tonsils, interferon-γ expression was highest in infected birds receiving the control diet (fiber × infection, P < 0.05); interferon-γ expression was lowest in infected birds fed the high Thr diet (Thr × infection, P < 0.05). There were no differences due to infection or Thr supplementation for cytokine expression in birds fed pectin-containing treatments. Overall, we conclude that although pectin has some protective function against coccidiosis, Thr supplementation had the greatest effect on intestinal immune response and maintenance of near normal growth in young broiler chicks infected with E. maxima.
Study of the biologic behavior of odontogenic keratocyst and orthokeratinaized odontogenic cyst using TGF-alpha and P53 markers.

PubMed

Deyhimi, Parviz; Hashemzadeh, Zahra

2014-04-01

Odontogenic keratocyst (OKC) is an aggressive cyst, and its recurrence rate is higher than that of other odontogenic cysts. Orthokeratinized odontogenic cyst (OOC) is less aggressive than OKC, but bears the probability of carcinomatous changes. In this study, we evaluated the expression and intensity of P53 and TGF-alpha in order to compare the biologic behavior or probable carcinomatous changes of these two cysts. In this cross-sectional study, 15 OKC and 15 OOC were stained immunohistochemically for P53 and TGF-alpha using the Novolink polymer method. Then, all slides were examined by an optical microscope with 400× magnification, and the stained cells in the basal and parabasal layers were counted. Finally, the results were analyzed by the Mann-Whitney and Wilcoxon tests (P-value<0.05). The difference between the expression of P53 and TGF alpha in the basal layer of OKC and OOC was not statistically significant (P-value>0.05), but the expression of P53 and TGF-alpha in the parabasal layer in OKC was statistically higher compared to OOC (P<0.05). Considering the known role of P53 and TGF-alpha in malignant changes and the higher expression of P53 and TGF-alpha in OKC compared to those in OOC, the probability of carcinomatous changes was higher in OKC than in OOC. Copyright © 2013 Elsevier GmbH. All rights reserved.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasper, Jocelyn S.; Harvard Medical School, Boston, MA; Arai, Takehiro

CUL7 is a member of the cullin RING ligase family and forms an SCF-like complex with SKP1 and FBXW8. CUL7 is required for normal mouse embryonic development and cellular proliferation, and is highly homologous to PARC, a p53-associated, parkin-like cytoplasmic protein. We determined that CUL7, in a manner similar to PARC, can bind directly to p53 but does not affect p53 expression. We identified a discrete, co-linear domain in CUL7 that is conserved in PARC and HERC2, and is necessary and sufficient for p53-binding. The presence of p53 stabilized expression of this domain and we demonstrate that this p53-binding domainmore » of CUL7 contributes to the cytoplasmic localization of CUL7. The results support the model that p53 plays a role in regulation of CUL7 activity.« less
Pontin is required for pre-TCR signaling at the β-selection checkpoint in T cell development.

PubMed

Boo, Kyungjin; Baek, Sung Hee; Lee, Ho

2014-04-25

Pontin is a chromatin remodeling factor that possesses both ATPase and DNA helicase activities. Based on high expression in lymphoid tissues, we examined whether Pontin has a T cell-specific function. We generated Pontin(f/f);Lck-Cre mice, in which Pontin can be conditionally deleted in T cells and then explored T cell-specific function of Pontin in vivo. Here, we show that specific abrogation of Pontin expression in T cells almost completely blocked development of αβ T cells at the β-selection checkpoint by inducing cell apoptosis indicating that Pontin is essential for early T cell development. Pontin-deficient thymocytes show a comparable expression level of T cell receptor (TCR)β chain, but have enhanced activation of p53 and Notch signaling compared to wild-type thymocytes. Intriguingly, the developmental block of αβ T cells can be partially rescued by loss of p53. Together, our data demonstrate a novel role of Pontin as a crucial regulator in pre-TCR signaling during T cell development. Copyright © 2014 Elsevier Inc. All rights reserved.
Phosphorylated Hsp27 activates ATM-dependent p53 signaling and mediates the resistance of MCF-7 cells to doxorubicin-induced apoptosis.

PubMed

Xu, Yimiao; Diao, Ying; Qi, Shimei; Pan, Xiaolong; Wang, Qi; Xin, Yinqiang; Cao, Xiang; Ruan, Jie; Zhao, Zhihui; Luo, Lan; Liu, Chang; Yin, Zhimin

2013-05-01

DNA damage activates p53 and its downstream target genes, which further leads to apoptosis or survival either by the cell cycle arrest or by DNA repair. In many tumors, the heat shock protein 27 (Hsp27) is expressed at high levels to provide protection against anticancer drugs. However, the roles of Hsp27 in p53-mediated cellular responses to DNA damage are controversial. Here, we investigated the interplay between the phosphorylation status of Hsp27 and p53 in kidney 293A (HEK293A) cells and found that over-expressing phosphorylated Hsp27 mimics (Hsp27-3D) activated p53/p21 in an ATM-dependent manner. In addition, incubation with doxorubicin (Dox), an anticancer drug, induced Hsp27 phosphorylation in human adenocarcinoma cells (MCF-7). In contrast, inhibition of Hsp27 phosphorylation retarded both p53 induction and p21 accumulation, and led to cell apoptosis. Furthermore, phosphorylated Hsp27 increased p53 nuclear importing and its downstream target gene expression such as p21 and MDM2, while de-phosphorylated Hsp27 impeded this procession. Taken together, our data suggest that Hsp27, in its phosphorylated or de-phosphorylated status, plays different roles in regulating p53 pathway and cell survival. Copyright © 2013 Elsevier Inc. All rights reserved.
Atmospheric Oxygen Inhibits Growth and Differentiation of Marrow-Derived Mouse Mesenchymal Stem Cells via a p53 Dependent Mechanism: Implications for Long-Term Culture Expansion

PubMed Central

Boregowda, Siddaraju; Krishnappa, Veena; Chambers, Jeremy; LoGrasso, Phillip V.; Lai, Wen-Tzu; Ortiz, Luis A.; Phinney, Donald G.

2013-01-01

Large scale expansion of human mesenchymal stem cells (MSCs) is routinely performed for clinical therapy. In contrast, developing protocols for large scale expansion of primary mouse MSCs has been more difficult due to unique aspects of rodent biology. Currently, established methods to isolate mouse MSCs select for rapidly dividing subpopulations that emerge from bone marrow cultures following long-term (months) expansion in atmospheric oxygen. Herein, we demonstrate that exposure to atmospheric oxygen rapidly induced p53, TOP2A and BAX expression and mitochondrial ROS generation in primary mouse MSCs resulting in oxidative stress, reduced cell viability and inhibition of cell proliferation. Alternatively, procurement and culture in 5% oxygen supported more prolific expansion of the CD45−ve/CD44+ve cell fraction in marrow, produced increased MSC yields following immuno-depletion, and supported sustained MSC growth resulting in a 2300-fold increase in cumulative cell yield by 4th passage. MSCs cultured in 5% oxygen also exhibited enhanced tri-lineage differentiation. The oxygen-induced stress response was dependent upon p53 since siRNA mediated knockdown of p53 in wild type cells or exposure of p53−/− MSCs to atmospheric oxygen failed to induce ROS generation, reduce viability, or arrest cell growth. These data indicate that long-term culture expansion of mouse MSCs in atmospheric oxygen selects for clones with absent or impaired p53 function, which allows cells to escape oxygen-induced growth inhibition. In contrast, expansion in 5% oxygen generates large numbers of primary mouse MSCs that retain sensitivity to atmospheric oxygen, and therefore a functional p53 protein, even after long-term expansion in vitro. PMID:22367737
Involvements of Estrogen Receptor, Proliferating Cell Nuclear Antigen and p53 in Endometrial Adenocarcinoma Development in Donryu Rats

PubMed Central

Yoshida, Midori; Katsuda, Shin-ichi; Maekawa, Akihiko

2012-01-01

Involvements of estrogen receptor (ER)α, proliferating cell nuclear antigen (PCNA) and p53 in the uterine carcinogenesis process in Donryu rats, a high yield strain of the uterine cancer were investigated immunohistochemically. ERα was expressed in atypical endometrial hyperplasia, accepted as a precancerous lesion of the uterine tumors, as well as well- and in moderately-differentiated endometrial adenocarcinomas, and the intensities of expression were similar to those in the luminal epithelial cells of the atrophic uterus at 15 months of age. The expression, however, was negative in the tumor cells of poorly differentiated type. Good growth of implanted grafts of the poorly-differentiated adenocarcinomas in both sexes with or without gonadectomy supported the estrogen independency of tumor progression to malignancy. PCNA labeling indices were increased with tumor development from atypical hyperplasia to adenocarcinoma. The tumor cells in poorly-differentiated adenocarcinomas were positive for p53 positive but negative for p21 expression, suggesting accumulation of mutated p53. These results indicate that the consistent ERα expression is involved in initiation and promotion steps of uterine carcinogenesis, but not progression. In addition, PCNA is related to tumor development and the expression of mutated p53 might be a late event during endometrial carcinogenesis. PMID:23345926

Increased expression of p53 and p21 (Waf1/Cip1) in the lesional skin of bleomycin-induced scleroderma.

PubMed

Yamamoto, Toshiyuki; Nishioka, Kiyoshi

2005-05-01

Systemic sclerosis (SSc) is a connective tissue disorder characterized by excessive deposition of extracellular matrix in the affected skin as well as various internal organs, vascular injury and immune abnormality; however, the etiology of SSc remains still unknown. We previously established an experimental mouse model for scleroderma by repeated local injections of bleomycin, a DNA damaging agent. In this study, we examined the induction of apoptosis and the expression of p53, p21 (Waf1/Cip1), and proliferating cell nuclear antigen (PCNA) in the lesional skin following bleomycin exposure in this model. Dermal sclerosis was induced by alternate day's injections of bleomycin for 4 weeks. TUNEL assay showed that apoptotic cells began to appear at 1 week after bleomycin exposure, and were prominently detected at 3-4 weeks. Immunohistochemical examination showed increased expression of p53 and p21 mainly in the infiltrating mononuclear cells at 2 weeks after bleomycin treatment. Bleomycin treatment markedly enhanced PCNA expression at 1-2 weeks, mainly in mesenchyme, as compared with control phosphate buffered saline treatment. Reverse transcriptase-polymerase chain reaction analysis showed that the expression of p53 and p21 mRNA was concurrently upregulated at 1-2 weeks after bleomycin treatment. Taken together, coordinate increased levels of p53 and p21 preceded the maximal induction of apoptosis and dermal sclerosis. Our findings suggest that apoptotic processes are involved in the pathophysiology of bleomycin-induced scleroderma, which may be mediated, in part, by the upregulation of p53 and p21.
Protosappanin B protects PC12 cells against oxygen-glucose deprivation-induced neuronal death by maintaining mitochondrial homeostasis via induction of ubiquitin-dependent p53 protein degradation.

PubMed

Zeng, Ke-Wu; Liao, Li-Xi; Zhao, Ming-Bo; Song, Fang-Jiao; Yu, Qian; Jiang, Yong; Tu, Peng-Fei

2015-03-15

Protosappanin B (PTB) is a bioactive dibenzoxocin derivative isolated from Caesalpinia sappan L. Here, we investigated the neuroprotective effects and the potential mechanisms of PTB on oxygen-glucose deprivation (OGD)-injured PC12 cells. Results showed that PTB significantly increased cell viability, inhibited cell apoptosis and up-regulated the expression of growth-associated protein 43 (a marker of neural outgrowth). Moreover, our study revealed that PTB effectively maintained mitochondrial homeostasis by up-regulation of mitochondrial membrane potential (MMP), inhibition of cytochrome c release from mitochondria and inactivation of mitochondrial caspase-9/3 apoptosis pathway. Further study showed that PTB significantly promoted cytoplasmic component degradation of p53 protein, a key negative regulator for mitochondrial function, resulting in a release of Bcl-2 from p53-Bcl-2 complex and an enhancing translocation of Bcl-2 to mitochondrial outer membrane. Finally, we found the degradation of p53 protein was induced by PTB via activation of a MDM2-dependent ubiquitination process. Taken together, our findings provided a new viewpoint of neuronal protection strategy for anoxia and ischemic injury with natural small molecular dibenzoxocin derivative by activating ubiquitin-dependent p53 protein degradation as well as increasing mitochondrial function. Copyright © 2015 Elsevier B.V. All rights reserved.
SIRT1 inhibition restores apoptotic sensitivity in p53-mutated human keratinocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herbert, Katharine J.; Cook, Anthony L., E-mail: Anthony.Cook@utas.edu.au; Snow, Elizabeth T., E-mail: elizabeth.snow@utas.edu.au

2014-06-15

Mutations to the p53 gene are common in UV-exposed keratinocytes and contribute to apoptotic resistance in skin cancer. P53-dependent activity is modulated, in part, by a complex, self-limiting feedback loop imposed by miR-34a-mediated regulation of the lysine deacetylase, SIRT1. Expression of numerous microRNAs is dysregulated in squamous and basal cell carcinomas; however the contribution of specific microRNAs to the pathogenesis of skin cancer remains untested. Through use of RNAi, miRNA target site blocking oligonucleotides and small molecule inhibitors, this study explored the influence of p53 mutational status, SIRT1 activity and miR-34a levels on apoptotic sensitivity in primary (NHEK) and p53-mutatedmore » (HaCaT) keratinocyte cell lines. SIRT1 and p53 are overexpressed in p53-mutated keratinocytes, whilst miR-34a levels are 90% less in HaCaT cells. HaCaTs have impaired responses to p53/SIRT1/miR-34a axis manipulation which enhanced survival during exposure to the chemotherapeutic agent, camptothecin. Inhibition of SIRT1 activity in this cell line increased p53 acetylation and doubled camptothecin-induced cell death. Our results demonstrate that p53 mutations increase apoptotic resistance in keratinocytes by interfering with miR-34a-mediated regulation of SIRT1 expression. Thus, SIRT1 inhibitors may have a therapeutic potential for overcoming apoptotic resistance during skin cancer treatment. - Highlights: • Impaired microRNA biogenesis promotes apoptotic resistance in HaCaT keratinocytes. • TP53 mutations suppress miR-34a-mediated regulation of SIRT1 expression. • SIRT1 inhibition increases p53 acetylation in HaCaTs, restoring apoptosis.« less
SOX14 activates the p53 signaling pathway and induces apoptosis in a cervical carcinoma cell line

PubMed Central

Stanisavljevic, Danijela; Petrovic, Isidora; Vukovic, Vladanka; Schwirtlich, Marija; Gredic, Marija; Stevanovic, Milena

2017-01-01

SOX14 is a member of the SOX family of transcription factors mainly involved in the regulation of neural development. Recently, it became evident that SOX14 is one of four hypermethylated genes in cervical carcinoma, considered as a tumor suppressor candidate in this type of malignancy. In this paper we elucidated the role of SOX14 in the regulation of malignant properties of cervical carcinoma cells in vitro. Functional analysis performed in HeLa cells revealed that SOX14 overexpression decreased viability and promoted apoptosis through altering the expression of apoptosis related genes. Our results demonstrated that overexpression of SOX14 initiated accumulation of p53, demonstrating potential cross-talk between SOX14 and the p53 signaling pathway. Further analysis unambiguously showed that SOX14 triggered posttranslational modification of p53 protein, as detected by the significantly increased level of phospho-p53 (Ser-15) in SOX14-overexpressing HeLa cells. Moreover, the obtained results revealed that SOX14 activated p53 protein, which was confirmed by elevated p21Waf1/Cip1, a well known target gene of p53. This study advances our understanding about the role of SOX14 and might explain the molecular mechanism by which this transcription factor could exert tumor suppressor properties in cervical carcinoma. PMID:28926586
MicroRNA501-5p induces p53 proteasome degradation through the activation of the mTOR/MDM2 pathway in ADPKD cells.

PubMed

de Stephanis, Lucia; Mangolini, Alessandra; Servello, Miriam; Harris, Peter C; Dell'Atti, Lucio; Pinton, Paolo; Aguiari, Gianluca

2018-09-01

Cell proliferation and apoptosis are typical hallmarks of autosomal dominant polycystic kidney disease (ADPKD) and cause the development of kidney cysts that lead to end-stage renal disease (ESRD). Many factors, impaired by polycystin complex loss of function, may promote these biological processes, including cAMP, mTOR, and EGFR signaling pathways. In addition, microRNAs (miRs) may also regulate the ADPKD related signaling network and their dysregulation contributes to disease progression. However, the role of miRs in ADPKD pathogenesis has not been fully understood, but also the function of p53 is quite obscure, especially its regulatory contribution on cell proliferation and apoptosis. Here, we describe for the first time that miR501-5p, upregulated in ADPKD cells and tissues, induces the activation of mTOR kinase by PTEN and TSC1 gene repression. The increased activity of mTOR kinase enhances the expression of E3 ubiquitin ligase MDM2 that in turn promotes p53 ubiquitination, leading to its degradation by proteasome machinery in a network involving p70S6K. Moreover, the overexpression of miR501-5p stimulates cell proliferation in kidney cells by the inhibition of p53 function in a mechanism driven by mTOR signaling. In fact, the downregulation of this miR as well as the pharmacological treatment with proteasome and mTOR inhibitors in ADPKD cells reduces cell growth by the activation of apoptosis. Consequently, the stimulation of cell death in ADPKD cells may occur through the inhibition of mTOR/MDM2 signaling and the restoring of p53 function. The data presented here confirm that the impaired mTOR signaling plays an important role in ADPKD. © 2018 Wiley Periodicals, Inc.
Adenovirally mediated p53 overexpression diversely influence the cell cycle of HEp-2 and CAL 27 cell lines upon cisplatin and methotrexate treatment.

PubMed

Kraljević Pavelić, Sandra; Marjanović, Marko; Poznić, Miroslav; Kralj, Marijeta

2009-12-01

p53 gene plays a crucial role in the response to therapy. Since it is inactivated in the majority of human cancers, it is strongly believed that the p53 mutations confer resistance to therapeutics. In this paper we analyzed the influence of two mechanistically diverse antitumor agents--cisplatin and methotrexate on the proliferation and cell cycle of two head and neck squamous cancer cell lines HEp-2 (wild type p53 gene, but HPV 18/E6-inactivated protein) and CAL 27 (mutated p53 gene), along with the influence of adenovirally mediated p53 overexpression in modulation of cisplatin and methoterexate effects, whereby subtoxic vector/compound concentrations were employed. p53 gene was introduced into tumor cells using adenoviral vector (AdCMV-p53). The cell cycle perturbations were measured by two parameter flow cytometry. The expression of p53, p21(WAF1/CIP1) and cyclin B1 proteins was examined using immunocytochemistry and western blot methods. In CAL 27 cells overexpression of p53 completely abrogated high S phase content observed in methotrexate-treated cells into a G1 and slight G2 arrest, while it sustained G2 arrest of the cells treated with cisplatin, along with the reduction of DNA synthesis and cyclin B1 expression. On the other hand, in HEp-2 cell line p53 overexpression slightly slowed down the progression through S phase in cells treated with methotrexate, decreased the cyclin B1 expression only after 24 h, and failed to sustain the G2 arrest after treatment with cisplatin alone. Instead, it increased the population of S phase cells that were not actively synthesizing DNA, sustained cyclin B1 expression and allowed the G2 cells to progress through mitosis. This study demonstrates that adenovirally mediated p53 overexpression at sub-cytotoxic levels enhanced the activity of low doses of cisplatin and methotrexate in HEp-2 and CAL 27 cells through changes in the cell cycle. However, the mechanisms of these effects differ depending on the genetic context and on the chemotherapeutics' modality of action.
Expression of P53 protein after exposure to ionizing radiation

NASA Astrophysics Data System (ADS)

Salazar, A. M.; Salvador, C.; Ruiz-Trejo, C.; Ostrosky, P.; Brandan, M. E.

2001-10-01

One of the most important tumor suppressor genes is p53 gene, which is involved in apoptotic cell death, cell differentiation and cell cycle arrest. The expression of p53 gene can be evaluated by determining the presence of P53 protein in cells using Western Blot assay with a chemiluminescent method. This technique has shown variabilities that are due to biological factors. Film developing process can influence the quality of the p53 bands obtained. We irradiated tumor cell lines and human peripheral lymphocytes with 137Cs and 60Co gamma rays to standardize irradiation conditions, to compare ionizing radiation with actinomycin D and to reduce the observed variability of P53 protein induction levels. We found that increasing radiation doses increase P53 protein induction while it decreases viability. We also conclude that ionizing radiation could serve as a positive control for Western Blot analysis of protein P53. In addition, our results show that the developing process may play an important role in the quality of P53 protein bands and data interpretation.
Mdm-2 binding and TAF(II)31 recruitment is regulated by hydrogen bond disruption between the p53 residues Thr18 and Asp21.

PubMed

Jabbur, James R; Tabor, Amy D; Cheng, Xiaodong; Wang, Hua; Uesugi, Motonari; Lozano, Guillermina; Zhang, Wei

2002-10-10

Analyses of five wild-type p53 containing cell lines revealed lineage specific differences in phosphorylation of Thr18 after treatment with ionizing (IR) or ultraviolet (UV) radiation. Importantly, Thr18 phosphorylation correlated with induction of the p53 downstream targets p21(Waf1/Cip1) (p21) and Mdm-2, suggesting a transactivation enhancing role. Thr18 phosphorylation has been shown to abolish side-chain hydrogen bonding between Thr18 and Asp21, an interaction necessary for stabilizing alpha-helical conformation within the transactivation domain. Mutagenesis-derived hydrogen bond disruption attenuated the interaction of p53 with the transactivation repressor Mdm-2 but had no direct effect on the interaction of p53 with the basal transcription factor TAF(II)31. However, prior incubation of p53 mutants with Mdm-2 modulated TAF(II)31 interaction with p53, suggesting Mdm-2 blocks the accessibility of p53 to TAF(II)31. Consistently, p53-null cells transfected with hydrogen bond disrupting p53 mutants demonstrated enhanced endogenous p21 expression, whereas p53/Mdm-2-double null cells exhibited no discernible differences in p21 expression. We conclude disruption of intramolecular hydrogen bonding between Thr18 and Asp21 enhances p53 transactivation by modulating Mdm-2 binding, facilitating TAF(II)31 recruitment.
[Circadian rhythm variation of the clock genes Per1 and cell cycle related genes in different stages of carcinogenesis of buccal mucosa in animal model].

PubMed

Tan, Xuemei; Ye, Hua; Yang, Kai; Chen, Dan; Tang, Hong

2015-07-01

To investigate the expression and circadian rhythm variation of biological clock gene Per1 and cell cycle genes p53, CyclinD1, cyclin-dependent kinases (CDK1), CyclinB1 in different stages of carcinogenesis in buccal mucosa and its relationship with the development of buccal mucosa carcinoma. Ninety golden hamsters were housed under 12 hours light-12 hours dark cycles, and the model of buccal squamous cell carcinoma was established by using the dimethylbenzanthracene (DMBA) to smear the golden hamster buccal mucosa. Before the DMBA was used and after DMBA was used 6 weeks and 14 weeks respectively, the golden hamsters were sacrificed at 6 different time points (5 rats per time point) within 24 hour, including 4, 8, 12, 16, 20 and 24 hour after lights onset (HALO), and the normal buccal mucosa, precancerous lesions and cancer tissue were obtained, respectively. HE stained sections were prepared to observe the canceration of each tissue. Real time RT-PCR was used to detect the mRNA expression of Per1, p53, CyclinD1, CDK1 and CyclinB1, and a cosine analysis method was applied to determine the circadian rhythm variation of Per1, p53, CyclinD1, CDK1 and CyclinB1 mRNA expression, which were characterized by median, amplitude and acrophase. The expression of Per1, p53, CDK1 and CyclinD1 mRNA in 6 different time points within 24 hours in the tissues of three different stages of carcinogenesis had circadian rhythm, respectively. However, the CyclinB1 mRNA was expressed with circadian rhythm just in normal and cancer tissue (P < 0.05), while in precancerous lesions the circadian rhythm was in disorder (P > 0.05). As the development of carcinoma, the median of Per1 and p53 mRNA expression were significantly decreased (P < 0.05), yet the median of CDK1, CyclinB1 and CyclinD1 mRNA expression were significantly increased (P < 0.05). The amplitude of Per1, p53 and CyclinD1 mRNA expression was significantly decreased as the development of carcinoma (P < 0.05), however the amplitude of CDK1 mRNA expression was significantly increased (P < 0.05). In addition, there was no significant difference in the amplitude of CyclinB1 mRNA expression. The time that the peak expression value of Per1 and CDK1 mRNA appeared (Acrophase) in precancerous lesions was remarkably earlier than that in normal tissues, but the acrophase of p53 and CyclinD1 mRNA expression was remarkably delayed. Moreover, the acrophase of CDK1 and CyclinB1 mRNA expression in cancer tissues was obviously earlier than that in normal tissues, yet there was no significant variation in acrophase of Per1, p53, CyclinD1 mRNA expression between normal tissues and cancer tissues. The circadian rhythm of clock gene Per1 and cell cycle genes p53, CyclinD1, CDK1, CyclinB1 expression remarkably varied with the occurrence and development of carcinoma. Further research into the interaction between circadian and cell cycle of two cycle activity and relationship with the carcinogenesis may providenew ideas and methods of individual treatment and the mechanism of carcinogenesis.
Nardilysin controls intestinal tumorigenesis through HDAC1/p53-dependent transcriptional regulation.

PubMed

Kanda, Keitaro; Sakamoto, Jiro; Matsumoto, Yoshihide; Ikuta, Kozo; Goto, Norihiro; Morita, Yusuke; Ohno, Mikiko; Nishi, Kiyoto; Eto, Koji; Kimura, Yuto; Nakanishi, Yuki; Ikegami, Kanako; Yoshikawa, Takaaki; Fukuda, Akihisa; Kawada, Kenji; Sakai, Yoshiharu; Ito, Akihiro; Yoshida, Minoru; Kimura, Takeshi; Chiba, Tsutomu; Nishi, Eiichiro; Seno, Hiroshi

2018-04-19

Colon cancer is a complex disease affected by a combination of genetic and epigenetic factors. Here we demonstrate that nardilysin (N-arginine dibasic convertase; NRDC), a metalloendopeptidase of the M16 family, regulates intestinal tumorigenesis via its nuclear functions. NRDC is highly expressed in human colorectal cancers. Deletion of the Nrdc gene in ApcMin mice crucially suppressed intestinal tumor development. In ApcMin mice, epithelial cell-specific deletion of Nrdc recapitulated the tumor suppression observed in Nrdc-null mice. Moreover, epithelial cell-specific overexpression of Nrdc significantly enhanced tumor formation in ApcMin mice. Notably, epithelial NRDC controlled cell apoptosis in a gene dosage-dependent manner. In human colon cancer cells, nuclear NRDC directly associated with HDAC1, and controlled both acetylation and stabilization of p53, with alterations of p53 target apoptotic factors. These findings demonstrate that NRDC is critically involved in intestinal tumorigenesis through its epigenetic regulatory function, and targeting NRDC may lead to a novel prevention or therapeutic strategy against colon cancer.
Functional consequences of inducible genetic elements from the p53 SOS response in a mammalian organ system.

PubMed

Guthrie, O'neil W

2017-10-01

In response to DNA damage from ultraviolet (UV) radiation, bacteria deploy the SOS response in order to limit cell death. This bacterial SOS response is characterized by an increase in the recA gene that transactivates expression of multiple DNA repair genes. The current series of experiments demonstrate that a mammalian organ system (the cochlea) that is not evolutionarily conditioned to UV radiation can elicit SOS responses that are reminiscent of that of bacteria. This mammalian SOS response is characterized by an increase in the p53 gene with activation of multiple DNA repair genes that harbor p53 response elements in their promoters. Furthermore, the experimental results provide support for the notion of a convergent trigger paradox, where independent SOS triggers facilitate disparate physiologic sequelae (loss vs. recovery of function). Therefore, it is proposed that the mammalian SOS response is multifunctional and manipulation of this endogenous response could be exploited in future biomedical interventions. Copyright © 2017 Elsevier Inc. All rights reserved.
BRCA1/2 and TP53 mutation status associates with PD-1 and PD-L1 expression in ovarian cancer.

PubMed

Wieser, Verena; Gaugg, Inge; Fleischer, Martina; Shivalingaiah, Giridhar; Wenzel, Soeren; Sprung, Susanne; Lax, Sigurd F; Zeimet, Alain G; Fiegl, Heidelinde; Marth, Christian

2018-04-03

Checkpoint molecules such as programmed cell death protein-1 (PD-1) and its ligand PD-L1 are critically required for tumor immune escape. The objective of this study was to investigate tumoral PD-1 and PD-L1 mRNA-expression in a cohort of ovarian cancer (OC) patients in relation to tumor mutations. We analyzed mRNA expression of PD-1 , PD-L1 and IFNG by quantitative real-time PCR in tissue of 170 patients with low grade-serous (LGSOC), high-grade serous (HGSOC), endometrioid and clear cell OC compared to 28 non-diseased tissues (ovaries and fallopian tubes) in relation to tumor protein 53 ( TP53 ) and breast cancer gene 1/2 ( BRCA1/2 ) mutation status. TP53 -mutated OC strongly expressed PD-L1 compared to TP53 wild-type OC ( p = 0.028) and BRCA1/2 -mutated OC increasingly expressed PD-1 ( p = 0.024) and PD-L1 ( p = 0.012) compared to BRCA1/2 wild-type OC. For the first time in human, we noted a strong correlation between tumoral IFNG and PD-1 or PD-L1 mRNA-expression, respectively ( p < 0.001). OC tissue increasingly expressed PD-1 compared to healthy controls (vs. ovaries: p < 0.001; vs. tubes: p = 0.018). PD-1 and PD-L1 mRNA-expression increased with higher tumor grade ( p = 0.008 and p = 0.027, respectively) and younger age (< median age, p = 0.001). Finally, in the major subgroup of our cohort, FIGO stage III/IV HGSOC, high PD-1 and PD-L1 mRNA-expression was associated with reduced progression-free ( p = 0.024) and overall survival ( p = 0.049) but only in the univariate analysis. Our study suggests that in OC PD-1 / PD-L1 mRNA-expression is controlled by IFNγ and affected by TP53 and BRCA1/2 mutations. We suggest that these mutations might serve as potential predictive factors that guide anti- PD1 / PD-L1 immunotherapy.
Actual Proliferating Index and p53 protein expression as prognostic marker in odontogenic cysts.

PubMed

Gadbail, A R; Chaudhary, M; Patil, S; Gawande, M

2009-10-01

The purpose of this study was to evaluate the biological aggressiveness of odontogenic keratocyst/keratocystic odontogenic tumour (KCOT), radicular cyst (RC) and dentigerous cyst (DC) by observing the actual proliferative activity of epithelium, and p53 protein expression. The actual proliferative activity was measured by Ki-67 Labelling Index and argyrophilic nucleolar organizing regions (AgNOR) count per nucleus. The p53 protein expression was also evaluated. Ki-67 positive cells were observed higher in suprabasal cell layers of KCOT with uniform distribution, a few of them were predominantly observed in basal cell layer in RC and DC. The AgNOR count was significantly higher in suprabasal cell layers of KCOT. The actual proliferative activity was noted to be higher in suprabasal cell layers of KCOT. The p53 immunolabelling was dense and scattered in basal and suprabasal cell layers in KCOT. The weakly stained p53 positive cells were observed diffusely distributed in KCOT, whereas they were mainly seen in basal cell layer of RC and DC. The quantitative and qualitative differences of the proliferative activity and the p53 protein expression in sporadic KCOT may be associated with intrinsic growth potential that could play a role in its development and explain locally aggressive biological behaviour. AgNOR count and p53 protein detection in odontogenic lesions can be of great consequence to predict the biological behaviour and prognosis.
Transient Protection from Heat-Stress Induced Apoptotic Stimulation by Metastasis-Associated Protein 1 in Pachytene Spermatocytes

PubMed Central

Guo, Sheng-jie; Li, Zhen; Feng, Xiao; Ma, Li; Zhang, Jin-shan; Liu, Xin-ping; Zhang, Yuan-qiang

2011-01-01

Background Deregulated thermal factors have been frequently implicated in the pathogenesis of male infertility, but the molecular basis through which certain responses are directed remain largely unknown. We previously reported that overexpression of exogenous Metastasis-associated protein 1 (MTA1) protects spermatogenic tumor cells GC-2spd (ts) against heat-induced apoptosis. To further dissect the underlying mechanism, we addressed here the fine coordination between MTA1 and p53 in pachytene spermatocytes upon hyperthermal stimulation. Methodology/Principal Findings High level of MTA1 expression sustained for 1.5 h in primary spermatocytes after heat stress before a notable decrease was detected conversely correlated to the gradual increase of acetylation status of p53 and of p21 level. Knockdown of the endogenous MTA1 in GC-2spd (ts) elevated the acetylation of p53 by diminishing the recruitment of HDAC2 and thereafter led to a dramatic increase of apoptosis after heat treatment. Consistent with this, in vivo interference of MTA1 expression in the testes of C57BL/6 mice also urged an impairment of the differentiation of spermatocytes and a disruption of Sertoli cell function due to the elevated apoptotic rate after heat stress. Finally, attenuated expression of MTA1 of pachytene spermatocytes was observed in arrested testes (at the round spermatid level) of human varicocele patients. Conclusions These data underscore a transient protective effect of this histone modifier in primary spermatocytes against heat-stress, which may operate as a negative coregulator of p53 in maintenance of apoptotic balance during early phase after hyperthermal stress. PMID:22022494
Impact of the Ki-67 labeling index and p53 expression status on disease-free survival in pT1 urothelial carcinoma of the bladder.

PubMed

Vetterlein, Malte W; Roschinski, Julia; Gild, Philipp; Marks, Phillip; Soave, Armin; Doh, Ousman; Isbarn, Hendrik; Höppner, Wolfgang; Wagner, Walter; Shariat, Shahrokh F; Brausi, Maurizio; Büscheck, Franziska; Sauter, Guido; Fisch, Margit; Rink, Michael

2017-12-01

The identification of protein biomarkers to guide treatment decisions regarding adjuvant therapies for high-risk non-muscle-invasive bladder cancer (NMIBC) has been of increasing interest. Evidence of the impact of tumor suppressor gene product p53 and cell proliferation marker Ki-67 on oncologic outcomes in bladder cancer patients at highest risk of recurrence and progression is partially contradictory. We sought to mirror contemporary expression patterns of p53 and Ki-67 in a select cohort of patients with pT1 bladder cancer. Patients from four Northern German institutions with a primary diagnosis of pT1 bladder cancer between 2009 and 2016 and complete data regarding p53 or Ki-67 expression status were included for final analyses. Baseline patient characteristics (age, gender, age-adjusted Charlson comorbidity index) and tumor characteristics [diagnostic sequence, tumor focality, concomitant carcinoma in situ, 1973 World Health Organization (WHO) grading, lymphovascular invasion, adjuvant instillation therapy] were abstracted by retrospective chart review. Immunohistochemistry for detection of p53 and Ki-67 expression was performed according to standardized protocols. Microscopic analyses were performed by central pathologic review. First, we compared patients with positive vs. negative p53 expression and Ki-67 labeling index [>40% vs. ≤40%; cutoffs based on best discriminative ability in univariable Cox regression analysis with disease-free survival (DFS) as endpoint] with regard to baseline and tumor characteristics. Second, we evaluated the effect of biomarker positivity on DFS by plotting univariable Kaplan-Meier curves and performing uni- and multivariable Cox regression analyses. Of 102 patients with complete information on p53 status, 44 (43.1%) were p53 positive, and they more often harbored concomitant carcinoma in situ (50.0% vs. 27.6%; P=0.032) and 1973 WHO grade 3 (97.7% vs. 69.0%; P=0.001) compared to their p53 negative counterparts. Of 79 patients with complete information on Ki-67 expression status, 30 (38.0%) had a labeling index >40%. Mean Ki-67 labeling index was higher in WHO grade 3 vs. grade 2 tumors (45.8 vs. 29.7; P=0.004). At a median follow-up of 51.0 months, 31/91 patients with complete follow-up information (34.1%) suffered from disease recurrence or progression. In univariable Kaplan-Meier analyses, no difference regarding DFS was found in p53 positive vs. negative (P=0.8) or Ki-67 labeling index >40% vs. ≤40% (P=0.078) patients. In multivariable analyses, Ki-67 labeling index >40% remained an independent predictor of DFS [hazard ratio (HR), 2.66; 95% confidence interval (CI), 1.02-6.95; P=0.046], after adjusting for p53 expression and lymphovascular invasion. However, p53 status was not associated with our endpoint (P=0.8). While we found an association of a Ki-67 labeling index >40% and shorter DFS in pT1 bladder cancer patients, this did not hold true for p53 positivity. Future research is needed to identify additional microscopic and molecular risk factors and biomarker panels to improve risk stratification and guide adjuvant therapies in those patients.
Crosstalk between the IGF-1R/AKT/mTORC1 pathway and the tumor suppressors p53 and p27 determines cisplatin sensitivity and limits the effectiveness of an IGF-1R pathway inhibitor

PubMed Central

Davaadelger, Batzaya; Duan, Lei; Perez, Ricardo E.; Gitelis, Steven; Maki, Carl G.

2016-01-01

The insulin-like growth factor-1 receptor (IGF-1R) signaling pathway is aberrantly activated in multiple cancers and can promote proliferation and chemotherapy resistance. Multiple IGF-1R inhibitors have been developed as potential therapeutics. However, these inhibitors have failed to increase patient survival when given alone or in combination with chemotherapy agents. The reason(s) for the disappointing clinical effect of these inhibitors is not fully understood. Cisplatin (CP) activated the IGF-1R/AKT/mTORC1 pathway and stabilized p53 in osteosarcoma (OS) cells. p53 knockdown reduced IGF-1R/AKT/mTORC1 activation by CP, and IGF-1R inhibition reduced the accumulation of p53. These data demonstrate positive crosstalk between p53 and the IGF-1R/AKT/mTORC1 pathway in response to CP. Further studies showed the effect of IGF-1R inhibition on CP response is dependent on p53 status. In p53 wild-type cells treated with CP, IGF-1R inhibition increased p53s apoptotic function but reduced p53-dependent senescence, and had no effect on long term survival. In contrast, in p53-null/knockdown cells, IGF-1R inhibition reduced apoptosis in response to CP and increased long term survival. These effects were due to p27 since IGF-1R inhibition stabilized p27 in CP-treated cells, and p27 depletion restored apoptosis and reduced long term survival. Together, the results demonstrate 1) p53 expression determines the effect of IGF-1R inhibition on cancer cell CP response, and 2) crosstalk between the IGF-1R/AKT/mTORC1 pathway and p53 and p27 can reduce cancer cell responsiveness to chemotherapy and may ultimately limit the effectiveness of IGF-1R pathway inhibitors in the clinic. PMID:27050276
Protein expression patterns of cell cycle regulators in operable breast cancer.

PubMed

Zagouri, Flora; Kotoula, Vassiliki; Kouvatseas, George; Sotiropoulou, Maria; Koletsa, Triantafyllia; Gavressea, Theofani; Valavanis, Christos; Trihia, Helen; Bobos, Mattheos; Lazaridis, Georgios; Koutras, Angelos; Pentheroudakis, George; Skarlos, Pantelis; Bafaloukos, Dimitrios; Arnogiannaki, Niki; Chrisafi, Sofia; Christodoulou, Christos; Papakostas, Pavlos; Aravantinos, Gerasimos; Kosmidis, Paris; Karanikiotis, Charisios; Zografos, George; Papadimitriou, Christos; Fountzilas, George

2017-01-01

To evaluate the prognostic role of elaborate molecular clusters encompassing cyclin D1, cyclin E1, p21, p27 and p53 in the context of various breast cancer subtypes. Cyclin E1, cyclin D1, p53, p21 and p27 were evaluated with immunohistochemistry in 1077 formalin-fixed paraffin-embedded tissues from breast cancer patients who had been treated within clinical trials. Jaccard distances were computed for the markers and the resulted matrix was used for conducting unsupervised hierarchical clustering, in order to identify distinct groups correlating with prognosis. Luminal B and triple-negative (TNBC) tumors presented with the highest and lowest levels of cyclin D1 expression, respectively. By contrast, TNBC frequently expressed Cyclin E1, whereas ER-positive tumors did not. Absence of Cyclin D1 predicted for worse OS, while absence of Cyclin E1 for poorer DFS. The expression patterns of all examined proteins yielded 3 distinct clusters; (1) Cyclin D1 and/or E1 positive with moderate p21 expression; (2) Cyclin D1 and/or E1, and p27 positive, p53 protein negative; and, (3) Cyclin D1 or E1 positive, p53 positive, p21 and p27 negative or moderately positive. The 5-year DFS rates for clusters 1, 2 and 3 were 70.0%, 79.1%, 67.4% and OS 88.4%, 90.4%, 78.9%, respectively. It seems that the expression of cell cycle regulators in the absence of p53 protein is associated with favorable prognosis in operable breast cancer.
Interleukin 6 downregulates p53 expression and activity by stimulating ribosome biogenesis: a new pathway connecting inflammation to cancer

PubMed Central

Brighenti, E; Calabrese, C; Liguori, G; Giannone, F A; Trerè, D; Montanaro, L; Derenzini, M

2014-01-01

Chronic inflammation is an established risk factor for the onset of cancer, and the inflammatory cytokine IL-6 has a role in tumorigenesis by enhancing proliferation and hindering apoptosis. As factors stimulating proliferation also downregulate p53 expression by enhancing ribosome biogenesis, we hypothesized that IL-6 may cause similar changes in inflamed tissues, thus activating a mechanism that favors neoplastic transformation. Here, we showed that IL-6 downregulated the expression and activity of p53 in transformed and untransformed human cell lines. This was the consequence of IL-6-dependent stimulation of c-MYC mRNA translation, which was responsible for the upregulation of rRNA transcription. The enhanced rRNA transcription stimulated the MDM2-mediated proteasomal degradation of p53, by reducing the availability of ribosome proteins for MDM2 binding. The p53 downregulation induced the acquisition of cellular phenotypic changes characteristic of epithelial–mesenchymal transition, such as a reduced level of E-cadherin expression, increased cell invasiveness and a decreased response to cytotoxic stresses. We found that these changes also occurred in colon epithelial cells of patients with ulcerative colitis, a very representative example of chronic inflammation at high risk for tumor development. Histochemical and immunohistochemical analysis of colon biopsy samples showed an upregulation of ribosome biogenesis, a reduced expression of p53, together with a focal reduction or absence of E-cadherin expression in chronic colitis in comparison with normal mucosa samples. These changes disappeared after treatment with anti-inflammatory drugs. Taken together, the present results highlight a new mechanism that may link chronic inflammation to cancer, based on p53 downregulation, which is activated by the enhancement of rRNA transcription upon IL-6 exposure. PMID:24531714
Gene mutations and increased levels of p53 protein in human squamous cell carcinomas and their cell lines.

PubMed Central

Burns, J. E.; Baird, M. C.; Clark, L. J.; Burns, P. A.; Edington, K.; Chapman, C.; Mitchell, R.; Robertson, G.; Soutar, D.; Parkinson, E. K.

1993-01-01

Using immunocytochemical and Western blotting techniques we have demonstrated the presence of abnormally high levels of p53 protein in 8/24 (33%) of human squamous cell carcinomas (SCC) and 9/18 (50%) of SCC cell lines. There was a correlation between the immunocytochemical results obtained with eight SCC samples and their corresponding cell lines. Direct sequencing of PCR-amplified, reverse transcribed, p53 mRNA confirmed the expression of point mutations in six of the positive cell lines and detected in-frame deletions in two others. We also detected two stop mutations and three out-of-frame deletions in five lines which did not express elevated levels of p53 protein. Several of the mutations found in SCC of the tongue (3/7) were in a region (codons 144-166) previously identified as being a p53 mutational hot spot in non-small cell lung tumours (Mitsudomi et al., 1992). In 11/13 cases only the mutant alleles were expressed suggesting loss or reduced expression of the wild type alleles in these cases. Six of the mutations were also detected in the SCCs from which the lines were derived, strongly suggesting that the mutations occurred, and were selected, in vivo. The 12th mutation GTG-->GGG (valine-->glycine) at codon 216 was expressed in line SCC-12 clone B along with an apparently normal p53 allele and is to our knowledge a novel mutation. Line BICR-19 also expressed a normal p53 allele in addition to one where exon 10 was deleted. Additionally 15 of the SCC lines (including all of those which did not show elevated p53 protein levels) were screened for the presence of human papillomavirus types 16 and 18 and were found to be negative. These results are discussed in relation to the pathogenesis of SCC and the immortalisation of human keratinocytes in vitro. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:8390283
Distinguishing Low-Risk Luminal A Breast Cancer Subtypes with Ki-67 and p53 Is More Predictive of Long-Term Survival

PubMed Central

Lee, Se Kyung; Bae, Soo Youn; Lee, Jun Ho; Lee, Hyun-Chul; Yi, Hawoo; Kil, Won Ho; Lee, Jeong Eon; Kim, Seok Won; Nam, Seok Jin

2015-01-01

Overexpression of p53 is the most frequent genetic alteration in breast cancer. Recently, many studies have shown that the expression of mutant p53 differs for each subtype of breast cancer and is associated with different prognoses. In this study, we aimed to determine the suitable cut-off value to predict the clinical outcome of p53 overexpression and its usefulness as a prognostic factor in each subtype of breast cancer, especially in luminal A breast cancer. Approval was granted by the Institutional Review Board of Samsung Medical Center. We analyzed a total of 7,739 patients who were surgically treated for invasive breast cancer at Samsung Medical Center between Dec 1995 and Apr 2013. Luminal A subtype was defined as ER&PR + and HER2- and was further subclassified according to Ki-67 and p53 expression as follows: luminal A (Ki-67-,p53-), luminal A (Ki-67+, p53-), luminal A (Ki-67 -, p53+) and luminal A (Ki-67+, p53+). Low-risk luminal A subtype was defined as negative for both Ki-67 and p53 (luminal A [ki-67-, p53-]), and others subtypes were considered to be high-risk luminal A breast cancer. A cut-off value of 10% for p53 was a good predictor of clinical outcome in all patients and luminal A breast cancer patients. The prognostic role of p53 overexpression for OS and DFS was only significant in luminal A subtype. The combination of p53 and Ki-67 has been shown to have the best predictive power as calculated by the area under curve (AUC), especially for long-term overall survival. In this study, we have shown that overexpression of p53 and Ki-67 could be used to discriminate low-risk luminal A subtype in breast cancer. Therefore, using the combination of p53 and Ki-67 expression in discriminating low-risk luminal A breast cancer may improve the prognostic power and provide the greatest clinical utility. PMID:26241661

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