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Sample records for p53 dependent apoptosis

  1. Interferons alpha and gamma induce p53-dependent and p53-independent apoptosis, respectively.

    PubMed

    Porta, Chiara; Hadj-Slimane, Reda; Nejmeddine, Mohamed; Pampin, Mathieu; Tovey, Michael G; Espert, Lucile; Alvarez, Sandra; Chelbi-Alix, Mounira K

    2005-01-20

    Type I interferon (IFN) enhances the transcription of the tumor suppressor gene p53. To elucidate the molecular mechanism mediating IFN-induced apoptosis, we analysed programmed cell death in response to type I (IFNalpha) or type II (IFNgamma) treatment in relation to p53 status. In two cell lines (MCF-7, SKNSH), IFNalpha, but not IFNgamma, enhanced apoptosis in a p53-dependent manner. Furthermore, only IFNalpha upregulated p53 as well as p53 target genes (Noxa, Mdm2 and CD95). The apoptotic response to IFNalpha decreased in the presence of ZB4, an anti-CD95 antibody, suggesting that CD95 is involved in this process. When p53 was inactivated by the E6 viral protein or the expression of a p53 mutant, IFNalpha-induced apoptosis and p53 target genes upregulation were abrogated. Altogether these results demonstrate that p53 plays a pivotal role in the IFNalpha-induced apoptotic response. IFNalpha-induced PML was unable to recruit p53 into nuclear bodies and its downregulation by siRNA did not alter CD95 expression. In contrast, IFNgamma-induced apoptosis is p53-independent. CD95 and IFN-regulatory factor 1 (IRF1) are directly upregulated by this cytokine. Apoptotic response to IFNgamma is decreased in the presence of ZB4 and strongly diminished by IRF1 siRNA, implicating both CD95 and IRF1 in IFNgamma-induced apoptotic response. Taken together, these results show that in two different cell lines, IFNalpha and IFNgamma, induce p53-dependent -independent apoptosis, respectively.

  2. Roscovitine-induced apoptosis of H1299 cells depends on functional status of p53.

    PubMed

    Slovackova, J; Smarda, J; Smardova, J

    2012-01-01

    Roscovitine, an inhibitor of cyclin-dependent kinases, is promising anticancer agent. Its antiproliferative and cytotoxic effects can be mediated by the p53 signaling pathway. To define the role of p53 in roscovitine-induced cell response, we prepared H1299/p53 cell lines inducibly expressing specific variants of p53 (p53wt and hotspot R175H, temperature-dependent P98A, A159V, S215G, Y220C, Y234C mutants). In the presence of roscovitine, each cell line variant behaved in specific way reflecting activity of the p53 protein. Roscovitine decreased production of the cell cycle inhibitor p21 and induced apoptosis. This effect was the most efficient in cells expressing p53wt protein with full activity. The cell expressing partially and conditionally active p53 mutants responded to roscovitine less efficiently. The cells expressing p53 mutants A159V and Y234C were very sensitive to roscovitine but their response was clearly temperature-dependent. The cells expressing P98A, S215G and Y220C p53 mutants exhibited only weak sensitivity to roscovitine and underwent apoptosis in low frequency. In principle, each td p53 mutant responded to roscovitine in distinct way. We showed clearly that the impact of roscovitine on H1299 cells depends on functional status of p53 they produce. This suggests that patients with tumors exhibiting specific p53 variants can benefit from the roscovitine therapy.

  3. Green Tea Polyphenols Induce p53-Dependent and p53-Independent Apoptosis in Prostate Cancer Cells through Two Distinct Mechanisms

    PubMed Central

    Gupta, Karishma; Thakur, Vijay S.; Bhaskaran, Natarajan; Nawab, Akbar; Babcook, Melissa A.; Jackson, Mark W.; Gupta, Sanjay

    2012-01-01

    Inactivation of the tumor suppressor gene p53 is commonly observed in human prostate cancer and is associated with therapeutic resistance. We have previously demonstrated that green tea polyphenols (GTP) induce apoptosis in prostate cancer cells irrespective of p53 status. However, the molecular mechanisms underlying these observations remain elusive. Here we investigated the mechanisms of GTP-induced apoptosis in human prostate cancer LNCaP cells stably-transfected with short hairpin-RNA against p53 (LNCaPshp53) and control vector (LNCaPshV). GTP treatment induced p53 stabilization and activation of downstream targets p21/waf1 and Bax in a dose-dependent manner specifically in LNCaPshV cells. However, GTP-induced FAS upregulation through activation of c-jun-N-terminal kinase resulted in FADD phosphorylation, caspase-8 activation and truncation of BID, leading to apoptosis in both LNCaPshV and LNCaPshp53 cells. In parallel, treatment of cells with GTP resulted in inhibition of survival pathway, mediated by Akt deactivation and loss of BAD phosphorylation more prominently in LNCaPshp53 cells. These distinct routes of cell death converged to a common pathway, leading to loss of mitochondrial transmembrane potential, cytochrome c release and activation of terminal caspases, resulting in PARP-cleavage. GTP-induced apoptosis was attenuated with JNK inhibitor, SP600125 in both cell lines; whereas PI3K-Akt inhibitor, LY294002 resulted in increased cell death prominently in LNCaPshp53 cells, establishing the role of two distinct pathways of GTP-mediated apoptosis. Furthermore, GTP exposure resulted in inhibition of class I HDAC protein, accumulation of acetylated histone-H3 in total cellular chromatin, resulting in increased accessibility of transcription factors to bind with the promoter sequences of p21/waf1 and Bax, regardless of the p53 status of cells, consistent with effects elicited by an HDAC inhibitor, trichostatin A. These results demonstrate that GTP induces

  4. BRCA1 regulates PIG3-mediated apoptosis in a p53-dependent manner.

    PubMed

    Zhang, Wenwen; Luo, Jiayan; Chen, Fengxia; Yang, Fang; Song, Wei; Zhu, Aiyu; Guan, Xiaoxiang

    2015-04-10

    BRCA1 plays a key role in the regulation of p53-dependent target gene transcription activation. Meanwhile, the p53 inducible gene 3 (PIG3) is a downstream target of p53 and is involved in p53-initiated apoptosis. However, little is known about whether BRCA1 can regulate PIG3-mediated apoptosis. Using a tissue microarray containing 149 breast cancer patient samples, we found that BRCA1 and PIG3 expression status were significantly positively correlated (r = 0.678, P < 0.001) and identified a significant positive correlation between high expression of BRCA1 and/or PIG3 and overall survival (OS). Moreover, we reveal that overexpression of BRCA1 significantly increased expression of PIG3 in cells with intact p53, whereas no increase in PIG3 was observed in p53-null MDA-MB-157 cells and p53-depleted HCT116p53-/- cells. Meanwhile, ectopic expression of BRCA1 could not lead to an increase expression level of prohibitin (PHB), which we have previously identified to induce PIG3-mediated apoptosis. Finally, ChIP analysis revealed that PHB can bind to the PIG3 promoter and activate PIG3 transcription independent of p53, although p53 presence did enhance this process. Taken together, our findings suggest that BRCA1 regulates PIG3-mediated apoptosis in a p53-dependent manner, and that PIG3 expression is associated with a better OS in breast cancer patients.

  5. The p53 isoform delta133p53ß regulates cancer cell apoptosis in a RhoB-dependent manner

    PubMed Central

    Arsic, Nikola; Ho-Pun-Cheung, Alexandre; Evelyne, Crapez; Assenat, Eric; Jarlier, Marta; Anguille, Christelle; Colard, Manon; Pezet, Mikaël

    2017-01-01

    The TP53 gene plays essential roles in cancer. Conventionally, wild type (WT) p53 is thought to prevent cancer development and metastasis formation, while mutant p53 has transforming abilities. However, clinical studies failed to establish p53 mutation status as an unequivocal predictive or prognostic factor of cancer progression. The recent discovery of p53 isoforms that can differentially regulate cell cycle arrest and apoptosis suggests that their expression, rather than p53 mutations, could be a more clinically relevant biomarker in patients with cancer. In this study, we show that the p53 isoform delta133p53ß is involved in regulating the apoptotic response in colorectal cancer cell lines. We first demonstrate delta133p53ß association with the small GTPase RhoB, a well-described anti-apoptotic protein. We then show that, by inhibiting RhoB activity, delta133p53ß protects cells from camptothecin-induced apoptosis. Moreover, we found that high delta133p53 mRNA expression levels are correlated with higher risk of recurrence in a series of patients with locally advanced rectal cancer (n = 36). Our findings describe how a WT TP53 isoform can act as an oncogene and add a new layer to the already complex p53 signaling network. PMID:28212429

  6. Radiation-Induced Salivary Gland Dysfunction Results From p53-Dependent Apoptosis

    SciTech Connect

    Avila, Jennifer L.; Grundmann, Oliver; Burd, Randy; Limesand, Kirsten H.

    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 glands 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.

  7. Calcium and S100B Regulation of p53-Dependent Cell Growth Arrest and Apoptosis

    PubMed Central

    Scotto, Christian; Deloulme, Jean Christophe; Rousseau, Denis; Chambaz, Edmond; Baudier, Jacques

    1998-01-01

    In glial C6 cells constitutively expressing wild-type p53, synthesis of the calcium-binding protein S100B is associated with cell density-dependent inhibition of growth and apoptosis in response to UV irradiation. A functional interaction between S100B and p53 was first demonstrated in p53-negative mouse embryo fibroblasts (MEF cells) by sequential transfection with the S100B and the temperature-sensitive p53Val135 genes. We show that in MEF cells expressing a low level of p53Val135, S100B cooperates with p53Val135 in triggering calcium-dependent cell growth arrest and cell death in response to UV irradiation at the nonpermissive temperature (37.5°C). Calcium-dependent growth arrest of MEF cells expressing S100B correlates with specific nuclear accumulation of the wild-type p53Val135 conformational species. S100B modulation of wild-type p53Val135 nuclear translocation and functions was confirmed with the rat embryo fibroblast (REF) cell line clone 6, which is transformed by oncogenic Ha-ras and overexpression of p53Val135. Ectopic expression of S100B in clone 6 cells restores contact inhibition of growth at 37.5°C, which also correlates with nuclear accumulation of the wild-type p53Val135 conformational species. Moreover, a calcium ionophore mediates a reversible G1 arrest in S100B-expressing REF (S100B-REF) cells at 37.5°C that is phenotypically indistinguishable from p53-mediated G1 arrest at the permissive temperature (32°C). S100B-REF cells proceeding from G1 underwent apoptosis in response to UV irradiation. Our data support a model in which calcium signaling and S100B cooperate with the p53 pathways of cell growth inhibition and apoptosis. PMID:9632811

  8. Imiquimod activates p53-dependent apoptosis in a human basal cell carcinoma cell line.

    PubMed

    Huang, Shi-Wei; Chang, Shu-Hao; Mu, Szu-Wei; Jiang, Hsin-Yi; Wang, Sin-Ting; Kao, Jun-Kai; Huang, Jau-Ling; Wu, Chun-Ying; Chen, Yi-Ju; Shieh, Jeng-Jer

    2016-03-01

    The tumor suppressor p53 controls DNA repair, cell cycle, apoptosis, autophagy and numerous other cellular processes. Imiquimod (IMQ), a synthetic toll-like receptor (TLR) 7 ligand for the treatment of superficial basal cell carcinoma (BCC), eliminates cancer cells by activating cell-mediated immunity and directly inducing apoptosis and autophagy in cancer cells. To evaluate the role of p53 in IMQ-induced cell death in skin cancer cells. The expression, phosphorylation and subcellular localization of p53 were detected by real-time PCR, luciferase reporter assay, cycloheximide chase analysis, immunoblotting and immunocytochemistry. Using BCC/KMC1 cell line as a model, the upstream signaling of p53 activation was dissected by over-expression of TLR7/8, the addition of ROS scavenger, ATM/ATR inhibitors and pan-caspase inhibitor. The role of p53 in IMQ-induced apoptosis and autophagy was assessed by genetically silencing p53 and evaluated by a DNA content assay, immunoblotting, LC3 puncta detection and acridine orange staining. IMQ induced p53 mRNA expression and protein accumulation, increased Ser15 phosphorylation, promoted nuclear translocation and up-regulated its target genes in skin cancer cells in a TLR7/8-independent manner. In BCC/KMC1 cells, the induction of p53 by IMQ was achieved through increased ROS production to stimulate the ATM/ATR-Chk1/Chk2 axis but was not mediated by inducing DNA damage. The pharmacological inhibition of ATM/ATR significantly suppressed IMQ-induced p53 activation and apoptosis. Silencing of p53 significantly decreased the IMQ-induced caspase cascade activation and apoptosis but enhanced autophagy. Mutant p53 skin cancer cell lines were more resistant to IMQ-induced apoptosis than wildtype p53 skin cancer cell lines. IMQ induced ROS production to stimulate ATM/ATR pathways and contributed to p53-dependent apoptosis in a skin basal cell carcinoma cell line BCC/KMC1. Copyright © 2015 Japanese Society for Investigative Dermatology

  9. Cadmium induces p53-dependent apoptosis in human prostate epithelial cells.

    PubMed

    Aimola, Pierpaolo; Carmignani, Marco; Volpe, Anna Rita; Di Benedetto, Altomare; Claudio, Luigi; Waalkes, Michael P; van Bokhoven, Adrie; Tokar, Erik J; Claudio, Pier Paolo

    2012-01-01

    Cadmium, a widespread toxic pollutant of occupational and environmental concern, is a known human carcinogen. The prostate is a potential target for cadmium carcinogenesis, although the underlying mechanisms are still unclear. Furthermore, cadmium may induce cell death by apoptosis in various cell types, and it has been hypothesized that a key factor in cadmium-induced malignant transformation is acquisition of apoptotic resistance. We investigated the in vitro effects produced by cadmium exposure in normal or tumor cells derived from human prostate epithelium, including RWPE-1 and its cadmium-transformed derivative CTPE, the primary adenocarcinoma 22Rv1 and CWR-R1 cells and LNCaP, PC-3 and DU145 metastatic cancer cell lines. Cells were treated for 24 hours with different concentrations of CdCl(2) and apoptosis, cell cycle distribution and expression of tumor suppressor proteins were analyzed. Subsequently, cellular response to cadmium was evaluated after siRNA-mediated p53 silencing in wild type p53-expressing RWPE-1 and LNCaP cells, and after adenoviral p53 overexpression in p53-deficient DU145 and PC-3 cell lines. The cell lines exhibited different sensitivity to cadmium, and 24-hour exposure to different CdCl(2) concentrations induced dose- and cell type-dependent apoptotic response and inhibition of cell proliferation that correlated with accumulation of functional p53 and overexpression of p21 in wild type p53-expressing cell lines. On the other hand, p53 silencing was able to suppress cadmium-induced apoptosis. Our results demonstrate that cadmium can induce p53-dependent apoptosis in human prostate epithelial cells and suggest p53 mutation as a possible contributing factor for the acquisition of apoptotic resistance in cadmium prostatic carcinogenesis.

  10. Cadmium Induces p53-Dependent Apoptosis in Human Prostate Epithelial Cells

    PubMed Central

    Aimola, Pierpaolo; Carmignani, Marco; Volpe, Anna Rita; Di Benedetto, Altomare; Claudio, Luigi; Waalkes, Michael P.; van Bokhoven, Adrie; Tokar, Erik J.; Claudio, Pier Paolo

    2012-01-01

    Cadmium, a widespread toxic pollutant of occupational and environmental concern, is a known human carcinogen. The prostate is a potential target for cadmium carcinogenesis, although the underlying mechanisms are still unclear. Furthermore, cadmium may induce cell death by apoptosis in various cell types, and it has been hypothesized that a key factor in cadmium-induced malignant transformation is acquisition of apoptotic resistance. We investigated the in vitro effects produced by cadmium exposure in normal or tumor cells derived from human prostate epithelium, including RWPE-1 and its cadmium-transformed derivative CTPE, the primary adenocarcinoma 22Rv1 and CWR-R1 cells and LNCaP, PC-3 and DU145 metastatic cancer cell lines. Cells were treated for 24 hours with different concentrations of CdCl2 and apoptosis, cell cycle distribution and expression of tumor suppressor proteins were analyzed. Subsequently, cellular response to cadmium was evaluated after siRNA-mediated p53 silencing in wild type p53-expressing RWPE-1 and LNCaP cells, and after adenoviral p53 overexpression in p53-deficient DU145 and PC-3 cell lines. The cell lines exhibited different sensitivity to cadmium, and 24-hour exposure to different CdCl2 concentrations induced dose- and cell type-dependent apoptotic response and inhibition of cell proliferation that correlated with accumulation of functional p53 and overexpression of p21 in wild type p53-expressing cell lines. On the other hand, p53 silencing was able to suppress cadmium-induced apoptosis. Our results demonstrate that cadmium can induce p53-dependent apoptosis in human prostate epithelial cells and suggest p53 mutation as a possible contributing factor for the acquisition of apoptotic resistance in cadmium prostatic carcinogenesis. PMID:22448262

  11. p53 at the endoplasmic reticulum regulates apoptosis in a Ca2+-dependent manner

    PubMed Central

    Giorgi, Carlotta; Bonora, Massimo; Sorrentino, Giovanni; Missiroli, Sonia; Poletti, Federica; Suski, Jan M.; Galindo Ramirez, Fabian; Rizzuto, Rosario; Di Virgilio, Francesco; Zito, Ester; Pandolfi, Pier Paolo; Wieckowski, Mariusz R.; Mammano, Fabio; Del Sal, Giannino; Pinton, Paolo

    2015-01-01

    The tumor suppressor p53 is a key protein in preventing cell transformation and tumor progression. Activated by a variety of stimuli, p53 regulates cell-cycle arrest and apoptosis. Along with its well-documented transcriptional control over cell-death programs within the nucleus, p53 exerts crucial although still poorly understood functions in the cytoplasm, directly modulating the apoptotic response at the mitochondrial level. Calcium (Ca2+) transfer between the endoplasmic reticulum (ER) and mitochondria represents a critical signal in the induction of apoptosis. However, the mechanism controlling this flux in response to stress stimuli remains largely unknown. Here we show that, in the cytoplasm, WT p53 localizes at the ER and at specialized contact domains between the ER and mitochondria (mitochondria-associated membranes). We demonstrate that, upon stress stimuli, WT p53 accumulates at these sites and modulates Ca2+ homeostasis. Mechanistically, upon activation, WT p53 directly binds to the sarco/ER Ca2+-ATPase (SERCA) pump at the ER, changing its oxidative state and thus leading to an increased Ca2+ load, followed by an enhanced transfer to mitochondria. The consequent mitochondrial Ca2+ overload causes in turn alterations in the morphology of this organelle and induction of apoptosis. Pharmacological inactivation of WT p53 or naturally occurring p53 missense mutants inhibits SERCA pump activity at the ER, leading to a reduction of the Ca2+ signaling from the ER to mitochondria. These findings define a critical nonnuclear function of p53 in regulating Ca2+ signal-dependent apoptosis. PMID:25624484

  12. A p53/ARF-dependent anticancer barrier activates senescence and blocks tumorigenesis without impacting apoptosis.

    PubMed

    Sinha, Vidya C; Qin, Lan; Li, Yi

    2015-02-01

    In response to oncogene activation and oncogene-induced aberrant proliferation, mammalian cells activate apoptosis and senescence, usually via the p53-ARF tumor-suppressor pathway. Apoptosis is a known barrier to cancer and is usually downregulated before full malignancy, but senescence as an anticancer barrier is controversial due to its presence in the tumor environment. In addition, senescence may aid cancer progression via releasing senescence-associated factors that instigate neighboring tumor cells. Here, it is demonstrated that apoptosis unexpectedly remains robust in ErbB2 (ERBB2/HER2)-initiated mammary early lesions arising in adult mice null for either p53 or ARF. These early lesions, however, downregulate senescence significantly. This diminished senescence response is associated with accelerated progression to cancer in ARF-null mice compared with ARF-wild-type mice. Thus, the ARF-p53 pathway is dispensable for the apoptosis anticancer barrier in the initiation of ErbB2 breast cancer, the apoptosis barrier alone cannot halt mammary tumorigenesis, and senescence is a key barrier against carcinogenesis. Findings in this relevant mouse model of HER2-driven breast cancer suggest that effective prevention relies upon preserving both ARF/p53-independent apoptosis and ARF/p53-dependent senescence. ©2014 American Association for Cancer Research.

  13. Zinc induces apoptosis on cervical carcinoma cells by p53-dependent and -independent pathway.

    PubMed

    Bae, Seog Nyeon; Lee, Keun Ho; Kim, Jin Hwi; Lee, Sung Jong; Park, Lae Ok

    2017-02-26

    There is evidence that the mineral zinc is involved in the apoptotic cell death of various carcinoma cells. In this study, we aim to determine whether zinc in the form of CIZAR induces apoptosis in cervical carcinoma cells by increasing intracellular zinc concentration. CaSki and HeLa cervical carcinoma cells and HPV-16 DNA-transformed keratinocyte (CRL2404) were treated with different concentrations of CIZAR. The cell viability test was carried out, the intracellular level of zinc was determined, and apoptosis was confirmed by flow cytometry after propidium iodide (PI) staining and fluorescence microscopy under DAPI staining. The expression of cell-cycle regulators was analyzed by Western blot, including the knock down of p53 and expression of HPV E6 and E7 genes by RT-PCR. Intracellular zinc accumulation induced the down-regulation of E6/E7 proteins through targeting of the specific transcriptional factors in the upstream regulatory region. p53 was induced after CIZAR treatment and p53-dependent apoptosis did not occur after knock down by p53 siRNA. In cervical carcinoma cells, regardless of HPV-infection, CIZAR induces apoptosis by the activation of the p53-independent pathways through the up-regulation of p21waf1, the down-regulation of c-Myc, and by decreasing the Bcl-2/Bax ratio. CIZAR induces apoptosis not only through the restoration of p53/Rb-dependent pathways in HPV-positive cells, but also through the activation of p53/Rb-independent pathways and the mitochondrial death-signal pathway in cervical carcinoma cells regardless of HPV-infection. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Non-thermal Plasma Causes p53-Dependent Apoptosis in Human Colon Carcinoma Cells

    PubMed Central

    Tuhvatulin, A.I.; Sysolyatina, E.V.; Scheblyakov, D.V.; Logunov, D.Yu.; Vasiliev, M.M.; Yurova, M.A.; Danilova, M.A.; Petrov, O.F.; Naroditsky, B.S.; Morfill, G.E.; Grigoriev, A.I.; Fortov, V.E.; Gintsburg, A.L.; Ermolaeva, S.A.

    2012-01-01

    Non-thermal plasma (NTP) consists of a huge amount of biologically active particles, whereas its temperature is close to ambient. This combination allows one to use NTP as a perspective tool for solving different biomedical tasks, including antitumor therapy. The treatment of tumor cells with NTP caused dose-dependent effects, such as growth arrest and apoptosis. However, while the outcome of NTP treatment has been established, the molecular mechanisms of the interaction between NTP and eukaryotic cells have not been thoroughly studied thus far. In this work, the mechanisms and the type of death of human colon carcinoma HCT 116 cells upon application of non-thermal argon plasma were studied. The effect of NTP on the major stress-activated protein p53 was investigated. The results demonstrate that the viability of HCT116 cells upon plasma treatment is dependent on the functional p53 protein. NTP treatment caused an increase in the intracellular concentration of p53 and the induction of the p53-controlled regulon. The p53-dependent accumulation of active proapoptotic caspase-3 was shown in NTP-treated cells. The study was the first to demonstrate that treatment of human colon carcinoma cells with NTP results in p53-dependent apoptosis. The results obtained contribute to our understanding of the applicability of NTP in antitumor therapy. PMID:23150806

  15. Novel small molecule induces p53-dependent apoptosis in human colon cancer cells

    SciTech Connect

    Park, Sang Eun; Min, Yong Ki; Ha, Jae Du; Kim, Bum Tae; Lee, Woo Ghil . E-mail: bigguy@krict.re.kr

    2007-07-06

    Using high-throughput screening with small-molecule libraries, we identified a compound, KCG165 [(2-(3-(2-(pyrrolidin-1-yl)ethoxy)-1,10b-dihydro-[1,2,4]triazolo[1,5-c] quinazolin-5(6H)-one)], which strongly activated p53-mediated transcriptional activity. KCG165-induced phosphorylations of p53 at Ser{sup 6}, Ser{sup 15}, and Ser{sup 20}, which are all key residues involved in the activation and stabilization of p53. Consistent with these findings, KCG165 increased level of p53 protein and led to the accumulation of transcriptionally active p53 in the nucleus with the increased occupancy of p53 in the endogenous promoter region of its downstream target gene, p21{sup WAF1/CIP}. Notably, KCG165-induced p53-dependent apoptosis in cancer cells. Furthermore, we suggested topoisomerase II as the molecular target of KCG165. Together, these results indicate that KCG165 may have potential applications as an antitumor agent.

  16. Viral Single-Strand DNA Induces p53-Dependent Apoptosis in Human Embryonic Stem Cells

    PubMed Central

    Hirsch, Matthew L.; Fagan, B. Matthew; Dumitru, Raluca; Bower, Jacquelyn J.; Yadav, Swati; Porteus, Matthew H.; Pevny, Larysa H.; Samulski, R. Jude

    2011-01-01

    Human embryonic stem cells (hESCs) are primed for rapid apoptosis following mild forms of genotoxic stress. A natural form of such cellular stress occurs in response to recombinant adeno-associated virus (rAAV) single-strand DNA genomes, which exploit the host DNA damage response for replication and genome persistence. Herein, we discovered a unique DNA damage response induced by rAAV transduction specific to pluripotent hESCs. Within hours following rAAV transduction, host DNA damage signaling was elicited as measured by increased gamma-H2AX, ser15-p53 phosphorylation, and subsequent p53-dependent transcriptional activation. Nucleotide incorporation assays demonstrated that rAAV transduced cells accumulated in early S-phase followed by the induction of apoptosis. This lethal signaling sequalae required p53 in a manner independent of transcriptional induction of Puma, Bax and Bcl-2 and was not evident in cells differentiated towards a neural lineage. Consistent with a lethal DNA damage response induced upon rAAV transduction of hESCs, empty AAV protein capsids demonstrated no toxicity. In contrast, DNA microinjections demonstrated that the minimal AAV origin of replication and, in particular, a 40 nucleotide G-rich tetrad repeat sequence, was sufficient for hESC apoptosis. Our data support a model in which rAAV transduction of hESCs induces a p53-dependent lethal response that is elicited by a telomeric sequence within the AAV origin of replication. PMID:22114676

  17. TEL/ETV6 induces apoptosis in 32D cells through p53-dependent pathways

    SciTech Connect

    Yamagata, Tetsuya; Maki, Kazuhiro; Waga, Kazuo; Mitani, Kinuko . E-mail: kinukom-tky@umin.ac.jp

    2006-08-25

    TEL is an ETS family transcription factor that is critical for maintaining hematopoietic stem cells in adult bone marrow. To investigate the roles of TEL in myeloid proliferation and differentiation, we introduced TEL cDNA into mouse myeloid 32Dcl3 cells. Overexpression of TEL repressed interleukin-3-dependent proliferation through blocking cell cycle progression. Also, the presence of TEL triggered apoptosis through the mitochondrial intrinsic pathway on exposure to granulocyte colony-stimulating factor. We found an increase in p53 protein and its DNA binding in the TEL-overexpressing cells. Forced expression of TEL stimulated transcription via the p53-responsive element and increased the expression of cellular target genes for p53 such as cell cycle regulator p21 and apoptosis inducer Puma. Consistently, induction of apoptosis was delayed by pifithrin-{alpha} treatment and completely blocked by increased expression of Bcl-2 in the TEL-overexpressing cells. These data collectively suggest that TEL exerts a tumor suppressive function through augmenting the p53 pathway and facilitates normal development of myelopoiesis.

  18. Knockdown of FAM3B triggers cell apoptosis through p53-dependent pathway.

    PubMed

    Mou, Haiwei; Li, Zongmeng; Yao, Pengle; Zhuo, Shu; Luan, Wei; Deng, Bo; Qian, Lihua; Yang, Mengmei; Mei, Hong; Le, Yingying

    2013-03-01

    FAM3B, also named PANDER, is a cytokine-like protein identified in 2002. Previous studies showed that FAM3B regulates glucose and lipid metabolism through interaction with liver and endocrine pancreas. FAM3B is also expressed by other tissues but its basic function is unclear. In this study, we found that FAM3B was expressed in mouse colon, intestine, liver and lung tissues and multiple types of cell lines, including murine pancreatic β-cell (Min6), microglia (N9) and muscle cell (C2C12); human colon cancer cells (HCT8, HCT116, HT29), hepatocyte (HL-7702), hepatocellular carcinoma cell (SMMC-7721) and lung carcinoma cell (A549). Inhibition of FAM3B expression by RNA interference induced apoptotic cell death of HCT8, HCT116, A549, N9, C2C12 and Min6 cells and decreased cell viability of HL-7702 and murine primary hepatocytes. Further studies with HCT8 cells showed that knockdown of FAM3B increased the protein levels of membrane-bound Fas and Bax, reduced the expression of Bcl-2, promoted the cleavage of caspases-8, -3, -9 and PARP, and the nuclear translocation of cleaved PARP. These results suggest that FAM3B silencing activates both extrinsic and intrinsic apoptotic pathways. Mechanistic studies showed that neutralizing antibody against Fas or silencing Fas-associated death domain had no effect on, while caspase inhibitors could significantly reverse FAM3B knockdown induced apoptosis, suggesting Fas and death receptor mediated extrinsic apoptotic pathway is not involved in FAM3B silencing induced apoptosis. Further studies showed that p53 was significantly upregulated after FAM3B knockdown. Silencing p53 could almost completely reverse FAM3B knockdown induced upregulation of Bax, downregulation of Bcl-2, cleavage of caspases-8, -9, -3, and apoptotic cell death, suggesting p53-dependent pathway plays critical roles in FAM3B silencing induced apoptosis. Studies with HCT116 cells confirmed that inhibition of FAM3B expression induced apoptosis through p53-dependent

  19. Gallium compound GaQ3-induced Ca2+ signalling triggers p53-dependent and -independent apoptosis in cancer cells

    PubMed Central

    Gogna, Rajan; Madan, Esha; Keppler, Bernhard; Pati, Uttam

    2012-01-01

    BACKGROUND AND PURPOSE A novel anti-neoplastic gallium complex GaQ3 (KP46), earlier developed by us, is currently in phase I clinical trial. GaQ3 induced S-phase arrest and apoptosis via caspase/PARP cleavage in a variety of cancers. However, the underlying mechanism of apoptosis is unknown. Here, we have explored the mechanism(s) of GaQ3-induced apoptosis in cancer cells, focusing on p53 and intracellular Ca2+ signalling. EXPERIMENTAL APPROACH GaQ3-induced cytotoxicity and apoptosis were determined in cancer cell lines, with different p53 status (p53+/+, p53−/− and p53 mutant). Time course analysis of intracellular Ca2+ calcium release, p53 promoter activation, p53-nuclear/cytoplasmic movements and reactive oxygen species (ROS) were conducted. Ca2+-dependent formation of the p53–p300 transcriptional complex was analysed by co-immunoprecipitation and chromatin immunoprecipitation. Ca2+ signalling, p53, p300 and ROS were serially knocked down to study Ca2+–p53–ROS ineractions in GaQ3-induced apoptosis. KEY RESULTS GaQ3 triggered intracellular Ca2+ release stabilizing p53–p300 complex and recruited p53 to p53 promoter, leading to p53 mRNA and protein synthesis. p53 induced higher intracellular Ca2+ release and ROS followed by activation of p53 downstream genes including those for the micro RNA mir34a. In p53−/− and p53 mutant cells, GaQ3-induced Ca2+-signalling generated ROS. ROS further increased membrane translocation of FAS and FAS-mediated extrinsic apoptosis. CONCLUSIONS AND IMPLICATIONS This study disclosed a novel mechanism of Ca2+-signalling-mediated p53 activation and ROS up-regulation. Understanding the mechanism of GaQ3-induced apoptosis will help establish this gallium-based organic compound as a potent anti-cancer drug. PMID:22074401

  20. Loss of CDKN2B promotes p53-dependent smooth muscle cell apoptosis and aneurysm formation

    PubMed Central

    Leeper, Nicholas J.; Raiesdana, Azad; Kojima, Yoko; Kundu, Ramendra K.; Cheng, Henry; Maegdefessel, Lars; Toh, Ryuji; Ahn, G-One; Ali, Ziad A.; Anderson, D. Ryan; Miller, Clint L.; Roberts, Scott C.; Spin, Joshua M.; de Almeida, Patricia E.; Wu, Joseph C.; Xu, Baohui; Cheng, Karen; Quertermous, Maximilian; Kundu, Soumajit; Kortekaas, Kim E.; Berzin, Erica; Downing, Kelly P.; Dalman, Ronald L.; Tsao, Philip S.; Schadt, Eric E.; Owens, Gary K.; Quertermous, Thomas

    2013-01-01

    Objective Genome wide association studies have implicated allelic variation at 9p21.3 in multiple forms of vascular disease, including atherosclerotic coronary heart disease and abdominal aortic aneurysm. As for other genes at 9p21.3, human eQTL studies have associated expression of the tumor suppressor gene CDKN2B with the risk haplotype, but its potential role in vascular pathobiology remains unclear. Methods and Results Here we employed vascular injury models and found that Cdkn2b knockout mice displayed the expected increase in proliferation after injury, but developed reduced neointimal lesions and larger aortic aneurysms. In situ and in vitro studies suggested that these effects were due to increased smooth muscle cell apoptosis. Adoptive bone marrow transplant studies confirmed that the observed effects of Cdkn2b were mediated through intrinsic vascular cells and were not dependent on bone marrow-derived inflammatory cells. Mechanistic studies suggested that the observed increase in apoptosis was due to a reduction in MDM2 and an increase in p53 signaling, possibly due in part to compensation by other genes at the 9p21.3 locus. Dual inhibition of both Cdkn2b and p53 led to a reversal of the vascular phenotype in each model. Conclusions These results suggest that reduced CDKN2B expression and increased SMC apoptosis may be one mechanism underlying the 9p21.3 association with aneurysmal disease. PMID:23162013

  1. Low Dose Radiation Hypersensitivity is Caused by p53-dependent Apoptosis

    SciTech Connect

    Enns, L; Bogen, K; Wizniak, J; Murtha, A; Weinfeld, M

    2004-04-08

    Exposure to environmental radiation and the application of new clinical modalities, such as radioimmunotherapy, have heightened the need to understand cellular responses to low dose and low-dose rate ionizing radiation. Many tumor cell lines have been observed to exhibit a hypersensitivity to radiation doses below 50 cGy, which manifests as a significant deviation from the clonogenic survival response predicted by a linear-quadratic fit to higher doses. However, the underlying processes for this phenomenon remain unclear. Using a gel microdrop/flow cytometry assay to monitor single cell proliferation at early times post irradiation, we examined the response of human A549 lung carcinoma, T98G glioma and MCF7 breast carcinoma cell lines exposed to gamma radiation doses from 0 to 200 cGy delivered at 0.18 and 22 cGy/min. The A549 and T98G cells, but not MCF7 cells, showed the marked hypersensitivity at doses <50 cGy. To further characterize the low-dose hypersensitivity, we examined the influence of low-dose radiation on cell cycle status and apoptosis by assays for active caspase-3 and phosphatidylserine translocation (annexin-V binding). We observed that caspase-3 activation and annexin-V binding mirrored the proliferation curves for the cell lines. Furthermore, the low-dose hypersensitivity and annexin-V binding to irradiated A549 and T98G cells were eliminated by treating the cells with pifithrin, an inhibitor of p53. When p53-inactive cell lines (2800T skin fibroblasts and HCT116 colorectal carcinoma cells) were examined for similar patterns, we found that there was no HRS and apoptosis was not detectable by annexin-V or caspase-3 assays. Our data therefore suggest that low-dose hypersensitivity is associated with p53-dependent apoptosis.

  2. Pivotal roles of p53 transcription-dependent and -independent pathways in manganese-induced mitochondrial dysfunction and neuronal apoptosis.

    PubMed

    Wan, Chunhua; Ma, Xa; Shi, Shangshi; Zhao, Jianya; Nie, Xiaoke; Han, Jingling; Xiao, Jing; Wang, Xiaoke; Jiang, Shengyang; Jiang, Junkang

    2014-12-15

    Chronic exposure to excessive manganese (Mn) has been known to lead to neuronal loss and a clinical syndrome resembling idiopathic Parkinson's disease (IPD). p53 plays an integral role in the development of various human diseases, including neurodegenerative disorders. However, the role of p53 in Mn-induced neuronal apoptosis and neurological deficits remains obscure. In the present study, we showed that p53 was critically involved in Mn-induced neuronal apoptosis in rat striatum through both transcription-dependent and -independent mechanisms. Western blot and immunohistochemistrical analyses revealed that p53 was remarkably upregulated in the striatum of rats following Mn exposure. Coincidentally, increased level of cleaved PARP, a hallmark of apoptosis, was observed. Furthermore, using nerve growth factor (NGF)-differentiated PC12 cells as a neuronal cell model, we showed that Mn exposure decreased cell viability and induced apparent apoptosis. Importantly, p53 was progressively upregulated, and accumulated in both the nucleus and the cytoplasm. The cytoplasmic p53 had a remarkable distribution in mitochondria, suggesting an involvement of p53 mitochondrial translocation in Mn-induced neuronal apoptosis. In addition, Mn-induced impairment of mitochondrial membrane potential (ΔΨm) could be partially rescued by pretreatment with inhibitors of p53 transcriptional activity and p53 mitochondrial translocation, Pifithrin-α (PFT-α) and Pifithrin-μ (PFT-μ), respectively. Moreover, blockage of p53 activities with PFT-α and PFT-μ significantly attenuated Mn-induced reactive oxidative stress (ROS) generation and mitochondrial H₂O₂ production. Finally, we observed that pretreatment with PFT-α and PFT-μ ameliorated Mn-induced apoptosis in PC12 cells. Collectively, these findings implicate that p53 transcription-dependent and -independent pathways may play crucial roles in the regulation of Mn-induced neuronal death.

  3. Nitric Oxide–Dependent Activation of P53 Suppresses Bleomycin-Induced Apoptosis in the Lung

    PubMed Central

    Davis, Darren W.; Weidner, Douglas A.; Holian, Andrij; McConkey, David J.

    2000-01-01

    Chronic inflammation leading to pulmonary fibrosis develops in response to environmental pollutants, radiotherapy, or certain cancer chemotherapeutic agents. We speculated that lung injury might be mediated by p53, a proapoptotic transcription factor widely implicated in the response of cells to DNA damage. Intratracheal administration of bleomycin led to caspase-mediated DNA fragmentation characteristic of apoptosis. The effects of bleomycin were associated with translocation of p53 from the cytosol to the nucleus only in alveolar macrophages that had been exposed to the drug in vivo, suggesting that the lung microenvironment regulated p53 activation. Experiments with a thiol antioxidant (N-acetylcysteine) in vivo and nitric oxide (NO) donors in vitro confirmed that reactive oxygen species were required for p53 activation. A specific role for NO was demonstrated in experiments with inducible nitric oxide synthase (iNOS)−/− macrophages, which failed to demonstrate nuclear p53 localization after in vivo bleomycin exposure. Strikingly, rates of bleomycin-induced apoptosis were at least twofold higher in p53−/− C57BL/6 mice compared with heterozygous or wild-type littermates. Similarly, levels of apoptosis were also twofold higher in the lungs of iNOS−/− mice than were observed in wild-type controls. Consistent with a role for apoptosis in chronic lung injury, levels of bleomycin-induced inflammation were substantially higher in iNOS−/− and p53−/− mice compared with wild-type controls. Together, our results demonstrate that iNOS and p53 mediate a novel apoptosis-suppressing pathway in the lung. PMID:10993916

  4. Pharmacologically blocking p53-dependent apoptosis protects intestinal stem cells and mice from radiation

    PubMed Central

    Wang, Xinwei; Wei, Liang; Cramer, Julie M.; Leibowitz, Brian J.; Judge, Colleen; Epperly, Michael; Greenberger, Joel; Wang, Fengchao; Li, Linheng; Stelzner, Matthias G.; Dunn, James C. Y.; Martin, Martin G.; Lagasse, Eric; Zhang, Lin; Yu, Jian

    2015-01-01

    Exposure to high levels of ionizing radiation (IR) leads to debilitating and dose-limiting gastrointestinal (GI) toxicity. Using three-dimensional mouse crypt culture, we demonstrated that p53 target PUMA mediates radiation-induced apoptosis via a cell-intrinsic mechanism, and identified the GSK-3 inhibitor CHIR99021 as a potent radioprotector. CHIR99021 treatment improved Lgr5+ cell survival and crypt regeneration after radiation in culture and mice. CHIR99021 treatment specifically blocked apoptosis and PUMA induction and K120 acetylation of p53 mediated by acetyl-transferase Tip60, while it had no effect on p53 stabilization, phosphorylation or p21 induction. CHIR99021 also protected human intestinal cultures from radiation by PUMA but not p21 suppression. These results demonstrate that p53 posttranslational modifications play a key role in the pathological and apoptotic response of the intestinal stem cells to radiation and can be targeted pharmacologically. PMID:25858503

  5. Pivotal roles of p53 transcription-dependent and -independent pathways in manganese-induced mitochondrial dysfunction and neuronal apoptosis

    SciTech Connect

    Wan, Chunhua; Ma, Xa; Shi, Shangshi; Zhao, Jianya; Nie, Xiaoke; Han, Jingling; Xiao, Jing; Wang, Xiaoke; Jiang, Shengyang; Jiang, Junkang

    2014-12-15

    Chronic exposure to excessive manganese (Mn) has been known to lead to neuronal loss and a clinical syndrome resembling idiopathic Parkinson's disease (IPD). p53 plays an integral role in the development of various human diseases, including neurodegenerative disorders. However, the role of p53 in Mn-induced neuronal apoptosis and neurological deficits remains obscure. In the present study, we showed that p53 was critically involved in Mn-induced neuronal apoptosis in rat striatum through both transcription-dependent and -independent mechanisms. Western blot and immunohistochemistrical analyses revealed that p53 was remarkably upregulated in the striatum of rats following Mn exposure. Coincidentally, increased level of cleaved PARP, a hallmark of apoptosis, was observed. Furthermore, using nerve growth factor (NGF)-differentiated PC12 cells as a neuronal cell model, we showed that Mn exposure decreased cell viability and induced apparent apoptosis. Importantly, p53 was progressively upregulated, and accumulated in both the nucleus and the cytoplasm. The cytoplasmic p53 had a remarkable distribution in mitochondria, suggesting an involvement of p53 mitochondrial translocation in Mn-induced neuronal apoptosis. In addition, Mn-induced impairment of mitochondrial membrane potential (ΔΨm) could be partially rescued by pretreatment with inhibitors of p53 transcriptional activity and p53 mitochondrial translocation, Pifithrin-α (PFT-α) and Pifithrin-μ (PFT-μ), respectively. Moreover, blockage of p53 activities with PFT-α and PFT-μ significantly attenuated Mn-induced reactive oxidative stress (ROS) generation and mitochondrial H{sub 2}O{sub 2} production. Finally, we observed that pretreatment with PFT-α and PFT-μ ameliorated Mn-induced apoptosis in PC12 cells. Collectively, these findings implicate that p53 transcription-dependent and -independent pathways may play crucial roles in the regulation of Mn-induced neuronal death. - Highlights: • p53 is robustly

  6. Sensitization of osteosarcoma cells to apoptosis by oncostatin M depends on STAT5 and p53.

    PubMed

    Chipoy, C; Brounais, B; Trichet, V; Battaglia, S; Berreur, M; Oliver, L; Juin, P; Rédini, F; Heymann, D; Blanchard, F

    2007-10-11

    Oncostatin M (OSM), a cytokine of the interleukin-6 family, induces growth arrest and differentiation of osteoblastic cells into glial-like/osteocytic cells. Here, we asked whether OSM regulates apoptosis of normal or transformed (osteosarcoma) osteoblasts. We show that OSM sensitizes cells to apoptosis induced by various death inducers such as staurosporine, ultraviolet or tumor necrosis factor-alpha. Apoptosis is mediated by the mitochondrial pathway, with release of cytochrome c from the mitochondria to the cytosol and activation of caspases-9 and -3. DNA micro-arrays revealed that OSM modulates the expression of Bax, Bad, Bnip3, Bcl-2 and Mcl-1. Pharmacological inhibitors, dominant-negative signal transducer and activator of transcriptions (STATs), stable RNA interference and knockout cells indicated that the transcription factors p53 and STAT5, which are activated by OSM, are implicated in the sensitization to apoptosis, being responsible for Bax induction and Bcl-2 reduction, respectively. These results indicate that, in addition to growth arrest and induced differentiation, OSM also sensitizes normal and transformed osteoblasts to apoptosis by a mechanism implicating (i) activation and nuclear translocation of STAT5 and p53 and (ii) an increased Bax/Bcl-2 ratio. Therefore, association of OSM with kinase inhibitors such as Sts represents new therapeutic opportunities for wild-type p53 osteosarcoma.

  7. Ubiquitin-specific protease 2 decreases p53-dependent apoptosis in cutaneous T-cell lymphoma.

    PubMed

    Wei, Tianling; Biskup, Edyta; Gjerdrum, Lise Mette Rahbek; Niazi, Omid; Ødum, Niels; Gniadecki, Robert

    2016-07-26

    Treatment of advanced cutaneous T-cell lymphomas (CTCL) is challenging because they are resistant to conventional chemotherapy. USP2 has been shown to promote resistance to chemotherapeutic agents in several cancer models.We show here USP2 is expressed in quiescent and activated T-cells and its expression is 50% lower in CTCL cell lines (MyLa2000, SeAx and Hut-78) than in normal T-cells. USP2 is expressed in neoplastic cells in early, plaque-stage mycosis fungoides (MF) and is downregulated in advanced tumor stages. Upon treatment with psoralen with UVA (PUVA) or a p53 activator, nutlin3a, USP2 expression is significantly increased in MyLa2000 (p53wt/wt), but not in SeAx (p53mut) or Hut-78 (p53-/-). USP2 knockdown decreases MyLa2000 cell viability after PUVA by 50% but not Hut-78, suggesting that the function of USP2 in CTCL cells is p53-dependent. Furthermore, USP2 knockdown results in a decreased Mdm2 expression and upregulation of p53. Taken together, our findings suggest that USP2 stabilizes Mdm2 which antagonizes pro-apoptotic activity of p53 and possibly contributes to therapeutic resistance in CTCL.

  8. Ubiquitin-specific protease 2 decreases p53-dependent apoptosis in cutaneous T-cell lymphoma

    PubMed Central

    Wei, Tianling; Biskup, Edyta; Rahbek Gjerdrum, Lise Mette; Niazi, Omid; Ødum, Niels; Gniadecki, Robert

    2016-01-01

    Treatment of advanced cutaneous T-cell lymphomas (CTCL) is challenging because they are resistant to conventional chemotherapy. USP2 has been shown to promote resistance to chemotherapeutic agents in several cancer models. We show here USP2 is expressed in quiescent and activated T-cells and its expression is 50% lower in CTCL cell lines (MyLa2000, SeAx and Hut-78) than in normal T-cells. USP2 is expressed in neoplastic cells in early, plaque-stage mycosis fungoides (MF) and is downregulated in advanced tumor stages. Upon treatment with psoralen with UVA (PUVA) or a p53 activator, nutlin3a, USP2 expression is significantly increased in MyLa2000 (p53wt/wt), but not in SeAx (p53mut) or Hut-78 (p53−/−). USP2 knockdown decreases MyLa2000 cell viability after PUVA by 50% but not Hut-78, suggesting that the function of USP2 in CTCL cells is p53-dependent. Furthermore, USP2 knockdown results in a decreased Mdm2 expression and upregulation of p53. Taken together, our findings suggest that USP2 stabilizes Mdm2 which antagonizes pro-apoptotic activity of p53 and possibly contributes to therapeutic resistance in CTCL. PMID:27351221

  9. p53-dependent NDRG1 expression induces inhibition of intestinal epithelial cell proliferation but not apoptosis after polyamine depletion.

    PubMed

    Zhang, Ai-Hong; Rao, Jaladanki N; Zou, Tongtong; Liu, Lan; Marasa, Bernard S; Xiao, Lan; Chen, Jie; Turner, Douglas J; Wang, Jian-Ying

    2007-07-01

    Normal intestinal mucosal growth requires polyamines that regulate expression of various genes involved in cell proliferation, growth arrest, and apoptosis. Our previous studies have shown that polyamine depletion stabilizes p53, resulting in inhibition of intestinal epithelial cell (IEC) proliferation, but the exact downstream targets of induced p53 are still unclear. The NDRG1 (N-myc downregulated gene-1) gene encodes a growth-related protein, and its transcription can be induced in response to stress. The current study tests the hypothesis that induced p53 inhibits IEC proliferation by upregulating NDRG1 expression following polyamine depletion. Depletion of cellular polyamines by inhibiting ornithine decarboxylase (ODC) with alpha-difluoromethylornithine not only induced p53 but also increased NDRG1 transcription as indicated by induction of the NDRG1 promoter activity and increased levels of NDRG1 mRNA and protein, all of which were prevented by using specific p53 siRNA and in cells with a targeted deletion of p53. In contrast, increased levels of cellular polyamines by ectopic expression of the ODC gene decreased p53 and repressed expression of NDRG1. Consistently, polyamine depletion-induced activation of the NDRG1-promoter was decreased when p53-binding sites within the NDRG1 proximal promoter region were deleted. Ectopic expression of the wild-type NDRG1 gene inhibited DNA synthesis and decreased final cell numbers regardless of the presence or absence of endogenous p53, whereas silencing NDRG1 promoted cell growth. However, overexpression of NDRG1 failed to directly induce cell death and to alter susceptibility to apoptosis induced by tumor necrosis factor-alpha/cycloheximide. These results indicate that NDRG1 is one of the direct mediators of induced p53 following polyamine depletion and that p53-dependent NDRG1 expression plays a critical role in the negative control of IEC proliferation.

  10. Mesothelin regulates growth and apoptosis in pancreatic cancer cells through p53-dependent and -independent signal pathway.

    PubMed

    Zheng, Chunning; Jia, Wei; Tang, Yong; Zhao, HuiLiang; Jiang, Yingsheng; Sun, Shaochuan

    2012-10-03

    of tumor growth under in vivo conditions. However, mesothelin-transfected cells exhibited a increased rate of tumor growth under in vivo conditions. Our data demonstrated that mesothelin promotes proliferation and inhibited apoptosis through p53-dependent pathway in pancreatic cancer cells with wt-p53, and p53-independent pathway in pancreatic cancer cells with mt-p53. Targeting mesothelin by shRNA is the important method for pancreatic cancer therapy.

  11. Down-regulation of wild-type p53 activity interferes with apoptosis of IL-3-dependent hematopoietic cells following IL-3 withdrawal.

    PubMed Central

    Gottlieb, E; Haffner, R; von Rüden, T; Wagner, E F; Oren, M

    1994-01-01

    Overexpression of wild-type p53 in p53-deficient leukemic cells induces apoptosis, which can be inhibited by hematopoietic survival factors. This suggests that p53 may contribute to survival factor dependence. To assess the role of wild-type p53 in mediating apoptosis following survival factor withdrawal, we interfered with endogenous p53 activity in interleukin-3 (IL-3)-dependent cells. Extended survival without IL-3 was conferred by recombinant retroviruses encoding either a full-length p53 mutant or a C-terminal p53 miniprotein, both of which can act as negative-dominant inhibitors of wild-type p53. On the other hand, excess wild-type p53 activity failed to elicit apoptosis as long as IL-3 was present. We propose that p53 is a positive, though not exclusive, mediator of survival factor dependence in hematopoietic cells. Images PMID:8137820

  12. Apoptosis induced by selenomethionine and methioninase is superoxide-mediated and p53-dependent in human prostate cancer cells

    PubMed Central

    Zhao, Rui; Domann, Frederick E.

    2006-01-01

    Selenomethionine (SeMet) is the chemical form or major component of selenium used for cancer chemoprevention in several clinical trials. However, evidence from experimental studies indicates that SeMet has weaker anticancer effects than most other forms of selenium. Recent studies showed that the anticancer activity of SeMet can be enhanced by methioninase (METase), indicating that SeMet metabolites are responsible for its anticancer activity. In the present study, we demonstrated that wild-type p53-expressing LNCaP human prostate cancer cells were more sensitive to co-treatment with SeMet and METase than p53-null PC3 human prostate cancer cells. SeMet and METase co-treatment significantly increased levels of superoxide and apoptosis in LNCaP cells. Co-treatment with SeMet and METase resulted in increased levels of phosphorylated p53 (serine15), total p53, Bax, and p21Waf1 proteins. LNCaP cells treated with SeMet and METase also showed p53 translocation to mitochondria, decreased mitochondrial membrane potential, cytochrome c release into the cytosol, and activation of caspase 9. The effects of SeMet and METase were suppressed by pre-treatment with a synthetic superoxide dismutase mimic or by knockdown of p53 via RNA interference. Reexpression of wild-type p53 in PC3 cells resulted in increases in superoxide production, apoptosis, and caspase 9 activity, and a decrease in mitochondrial membrane potential following co-treatment with SeMet and METase. Our study demonstrates that apoptosis induced by SeMet plus METase is superoxide-mediated and p53-dependent via mitochondrial pathway(s). These results suggest that superoxide and p53 may play a role in cancer chemoprevention by selenium. PMID:17172431

  13. Caspase-dependent Proteolysis of Human Ribonucleotide Reductase Small Subunits R2 and p53R2 during Apoptosis*

    PubMed Central

    Tebbi, Ali; Guittet, Olivier; Tuphile, Karine; Cabrié, Aimeric; Lepoivre, Michel

    2015-01-01

    Ribonucleotide reductase (RnR) is a key enzyme synthesizing deoxyribonucleotides for DNA replication and repair. In mammals, the R1 catalytic subunit forms an active complex with either one of the two small subunits R2 and p53R2. Expression of R2 is S phase-specific and required for DNA replication. The p53R2 protein is expressed throughout the cell cycle and in quiescent cells where it provides dNTPs for mitochondrial DNA synthesis. Participation of R2 and p53R2 in DNA repair has also been suggested. In this study, we investigated the fate of the RnR subunits during apoptosis. The p53R2 protein was cleaved in a caspase-dependent manner in K-562 cells treated with inhibitors of the Bcr-Abl oncogenic kinase and in HeLa 229 cells incubated with TNF-α and cycloheximide. The cleavage site was mapped between Asp342 and Asn343. Caspase attack released a C-terminal p53R2 peptide of nine residues containing the conserved heptapeptide essential for R1 binding. As a consequence, the cleaved p53R2 protein was inactive. In vitro, purified caspase-3 and -8 could release the C-terminal tail of p53R2. Knocking down these caspases, but not caspase-2, -7, and -10, also inhibited p53R2 cleavage in cells committed to die via the extrinsic death receptor pathway. The R2 subunit was subjected to caspase- and proteasome-dependent proteolysis, which was prevented by siRNA targeting caspase-8. Knocking down caspase-3 was ineffective. Protein R1 was not subjected to degradation. Adding deoxyribonucleosides to restore dNTP pools transiently protected cells from apoptosis. These data identify RnR activity as a prosurvival function inactivated by proteolysis during apoptosis. PMID:25878246

  14. Histone deacetylase inhibitors prime medulloblastoma cells for chemotherapy-induced apoptosis by enhancing p53-dependent Bax activation.

    PubMed

    Häcker, S; Karl, S; Mader, I; Cristofanon, S; Schweitzer, T; Krauss, J; Rutkowski, S; Debatin, K-M; Fulda, S

    2011-05-12

    Despite aggressive therapies, the prognosis of children with high-risk medulloblastoma is still poor, thus underscoring the need to develop novel treatment strategies. Here, we report that histone deacetylase inhibitors (HDACI), that is, MS-275, valproic acid or SAHA, provide a novel strategy for sensitization of medulloblastoma to DNA-damaging drugs such as Doxorubicin, VP16 and Cisplatin by promoting p53-dependent, mitochondrial apoptosis. Mechanistic studies reveal that single-agent treatment with MS-275 causes acetylation of the non-histone protein Ku70, an event reported to release Bax from Ku70, whereas DNA-damaging drugs trigger p53 acetylation and accumulation. Combined treatment with MS-275 and Doxorubicin or VP16 cooperates to promote binding of p53 to Bax and p53-dependent Bax activation, resulting in enhanced loss of mitochondrial membrane potential, cytochrome c release and caspase-dependent apoptosis. Overexpression of Bcl-2 almost completely abolishes the MS-275-mediated chemosensitization, underlining the importance of the mitochondrial pathway for inducing apoptosis. Also, MS-275 cooperates with chemotherapeutics to inhibit long-term clonogenic survival. Most importantly, MS-275 increases chemotherapeutic drug-induced apoptosis in primary medulloblastoma samples, and cooperates with Doxorubicin to suppress medulloblastoma growth in an in vivo model, which underscores the clinical relevance of the findings. Thus, HDACI such as MS-275 present a promising approach for chemosensitization of medulloblastoma by enhancing mitochondrial apoptosis in a p53-dependent manner. These findings have important clinical implications for the design of experimental treatment protocols for medulloblastoma.

  15. Folate stress induces apoptosis via p53-dependent de novo ceramide synthesis and up-regulation of ceramide synthase 6.

    PubMed

    Hoeferlin, L Alexis; Fekry, Baharan; Ogretmen, Besim; Krupenko, Sergey A; Krupenko, Natalia I

    2013-05-03

    We have investigated the role of ceramide in the cellular adaptation to folate stress induced by Aldh1l1, the enzyme involved in the regulation of folate metabolism. Our previous studies demonstrated that Aldh1l1, similar to folate deficiency, evokes metabolic stress and causes apoptosis in cancer cells. Here we report that the expression of Aldh1l1 in A549 or HCT116 cells results in the elevation of C16-ceramide and a transient up-regulation of ceramide synthase 6 (CerS6) mRNA and protein. Pretreatment with ceramide synthesis inhibitors myriocin and fumonisin B1 or siRNA silencing of CerS6 prevented C16-ceramide accumulation and rescued cells supporting the role of CerS6/C16-ceramide as effectors of Aldh1l1-induced apoptosis. The CerS6 activation by Aldh1l1 and increased ceramide generation were p53-dependent; this effect was ablated in p53-null cells. Furthermore, the expression of wild type p53 but not transcriptionally inactive R175H p53 mutant strongly elevated CerS6. Also, this dominant negative mutant prevented accumulation of CerS6 in response to Aldh1l1, indicating that CerS6 is a transcriptional target of p53. In support of this mechanism, bioinformatics analysis revealed the p53 binding site 3 kb downstream of the CerS6 transcription start. Interestingly, ceramide elevation in response to Aldh1l1 was inhibited by silencing of PUMA, a proapoptotic downstream effector of p53 whereas the transient expression of CerS6 elevated PUMA in a p53-dependent manner indicating reciprocal relationships between ceramide and p53/PUMA pathways. Importantly, folate withdrawal also induced CerS6/C16-ceramide elevation accompanied by p53 accumulation. Overall, these novel findings link folate and de novo ceramide pathways in cellular stress response.

  16. Zinc Deficiency Induces Apoptosis via Mitochondrial p53- and Caspase-Dependent Pathways in Human Neuronal Precursor Cells

    ERIC Educational Resources Information Center

    Seth, Rohit; Corniola, Rikki S.; Gower-Winter, Shannon D.; Morgan, Thomas J., Jr.; Bishop, Brian; Levenson, Cathy W.

    2015-01-01

    Previous studies have shown that zinc deficiency leads to apoptosis of neuronal precursor cells in vivo and in vitro. In addition to the role of p53 as a nuclear transcription factor in zinc deficient cultured human neuronal precursors (NT-2), we have now identified the translocation of phosphorylated p53 to the mitochondria and p53-dependent…

  17. Aciculatin Induces p53-Dependent Apoptosis via MDM2 Depletion in Human Cancer Cells In Vitro and In Vivo

    PubMed Central

    Lai, Chin-Yu; Tsai, An-Chi; Chen, Mei-Chuan; Chang, Li-Hsun; Sun, Hui-Lung; Chang, Ya-Ling; Chen, Chien-Chih

    2012-01-01

    Aciculatin, a natural compound extracted from the medicinal herb Chrysopogon aciculatus, shows potent anti-cancer potency. This study is the first to prove that aciculatin induces cell death in human cancer cells and HCT116 mouse xenografts due to G1 arrest and subsequent apoptosis. The primary reason for cell cycle arrest and cell death was p53 accumulation followed by increased p21 level, dephosphorylation of Rb protein, PUMA expression, and induction of apoptotic signals such as cleavage of caspase-9, caspase-3, and PARP. We demonstrated that p53 allele-null (−/−) (p53-KO) HCT116 cells were more resistant to aciculatin than cells with wild-type p53 (+/+). The same result was achieved by knocking down p53 with siRNA in p53 wild-type cells, indicating that p53 plays a crucial role in aciculatin-induced apoptosis. Although DNA damage is the most common event leading to p53 activation, we found only weak evidence of DNA damage after aciculatin treatment. Interestingly, the aciculatin-induced downregulation of MDM2, an important negative regulator of p53, contributed to p53 accumulation. The anti-cancer activity and importance of p53 after aciculatin treatment were also confirmed in the HCT116 xenograft models. Collectively, these results indicate that aciculatin treatment induces cell cycle arrest and apoptosis via inhibition of MDM2 expression, thereby inducing p53 accumulation without significant DNA damage and genome toxicity. PMID:22912688

  18. Regulation of Caenorhabditis elegans p53/CEP-1–Dependent Germ Cell Apoptosis by Ras/MAPK Signaling

    PubMed Central

    Rutkowski, Rachael; Dickinson, Robin; Stewart, Graeme; Craig, Ashley; Schimpl, Marianne; Keyse, Stephen M.; Gartner, Anton

    2011-01-01

    Maintaining genome stability in the germline is thought to be an evolutionarily ancient role of the p53 family. The sole Caenorhabditis elegans p53 family member CEP-1 is required for apoptosis induction in meiotic, late-stage pachytene germ cells in response to DNA damage and meiotic recombination failure. In an unbiased genetic screen for negative regulators of CEP-1, we found that increased activation of the C. elegans ERK orthologue MPK-1, resulting from either loss of the lip-1 phosphatase or activation of let-60 Ras, results in enhanced cep-1–dependent DNA damage induced apoptosis. We further show that MPK-1 is required for DNA damage–induced germ cell apoptosis. We provide evidence that MPK-1 signaling regulates the apoptotic competency of germ cells by restricting CEP-1 protein expression to cells in late pachytene. Restricting CEP-1 expression to cells in late pachytene is thought to ensure that apoptosis doesn't occur in earlier-stage cells where meiotic recombination occurs. MPK-1 signaling regulates CEP-1 expression in part by regulating the levels of GLD-1, a translational repressor of CEP-1, but also via a GLD-1–independent mechanism. In addition, we show that MPK-1 is phosphorylated and activated upon ionising radiation (IR) in late pachytene germ cells and that MPK-1–dependent CEP-1 activation may be in part direct, as these two proteins interact in a yeast two-hybrid assay. In summary, we report our novel finding that MAP kinase signaling controls CEP-1–dependent apoptosis by several different pathways that converge on CEP-1. Since apoptosis is also restricted to pachytene stage cells in mammalian germlines, analogous mechanisms regulating p53 family members are likely to be conserved throughout evolution. PMID:21901106

  19. Regulation of Caenorhabditis elegans p53/CEP-1-dependent germ cell apoptosis by Ras/MAPK signaling.

    PubMed

    Rutkowski, Rachael; Dickinson, Robin; Stewart, Graeme; Craig, Ashley; Schimpl, Marianne; Keyse, Stephen M; Gartner, Anton

    2011-08-01

    Maintaining genome stability in the germline is thought to be an evolutionarily ancient role of the p53 family. The sole Caenorhabditis elegans p53 family member CEP-1 is required for apoptosis induction in meiotic, late-stage pachytene germ cells in response to DNA damage and meiotic recombination failure. In an unbiased genetic screen for negative regulators of CEP-1, we found that increased activation of the C. elegans ERK orthologue MPK-1, resulting from either loss of the lip-1 phosphatase or activation of let-60 Ras, results in enhanced cep-1-dependent DNA damage induced apoptosis. We further show that MPK-1 is required for DNA damage-induced germ cell apoptosis. We provide evidence that MPK-1 signaling regulates the apoptotic competency of germ cells by restricting CEP-1 protein expression to cells in late pachytene. Restricting CEP-1 expression to cells in late pachytene is thought to ensure that apoptosis doesn't occur in earlier-stage cells where meiotic recombination occurs. MPK-1 signaling regulates CEP-1 expression in part by regulating the levels of GLD-1, a translational repressor of CEP-1, but also via a GLD-1-independent mechanism. In addition, we show that MPK-1 is phosphorylated and activated upon ionising radiation (IR) in late pachytene germ cells and that MPK-1-dependent CEP-1 activation may be in part direct, as these two proteins interact in a yeast two-hybrid assay. In summary, we report our novel finding that MAP kinase signaling controls CEP-1-dependent apoptosis by several different pathways that converge on CEP-1. Since apoptosis is also restricted to pachytene stage cells in mammalian germlines, analogous mechanisms regulating p53 family members are likely to be conserved throughout evolution.

  20. Hyaluronan suppresses lidocaine-induced apoptosis of human chondrocytes in vitro by inhibiting the p53-dependent mitochondrial apoptotic pathway

    PubMed Central

    Lee, Yoon-Jin; Kim, Soo A; Lee, Sang-Han

    2016-01-01

    Aim: Intra-articular injection of local anesthetics (LAs) is a common procedure for therapeutic purposes. However, LAs have been found toxic to articular cartilage, and hyaluronan may attenuate this toxicity. In this study we investigated whether hyaluronan attenuated lidocaine-induced chondrotoxicity, and if so, to elucidate the underlying mechanisms. Methods: Human chondrocyte cell line SW1353 and newly isolated murine chondrocytes were incubated in culture medium containing hyaluronan and/or lidocaine for 72 h. Cell viability was evaluated using MTT assay. Cell apoptosis was detected with DAPI staining, caspase 3/7 activity assay and flow cytometry. Cell cycle distributions, ROS levels and mitochondrial membrane potential (ΔΨm) were determined using flow cytometry. The expression of p53 and p53-regulated gene products was measured with Western blotting. Results: Lidocaine (0.005%−0.03%) dose-dependently decreased the viability of SW1353 cells. This local anesthetic (0.015%, 0.025%) induced apoptosis, G2/M phase arrest and loss of ΔΨm, and markedly increased ROS production in SW1353 cells. Hyaluronan (50−800 μg/mL) alone did not affect the cell viability, but co-treatment with hyaluronan (200 μg/mL) significantly attenuated lidocaine-induced apoptosis and other abnormalities in SW1353 cells. Furthermore, co-treatment with lidocaine and hyaluronan significantly decreased the levels of p53 and its transcription targets Bax and p21 in SW1353 cells, although treatment with lidocaine alone did not significantly change these proteins. Similar results were obtained in ex vivo cultured murine chondrocytes. Conclusion: Hyaluronan suppresses lidocaine-induced apoptosis of human chondrocytes in vitro through inhibiting the p53-dependent mitochondrial apoptotic pathway. PMID:27041463

  1. FGF1 nuclear translocation is required for both its neurotrophic activity and its p53-dependent apoptosis protection.

    PubMed

    Rodriguez-Enfedaque, Aida; Bouleau, Sylvina; Laurent, Maryvonne; Courtois, Yves; Mignotte, Bernard; Vayssière, Jean-Luc; Renaud, Flore

    2009-11-01

    Fibroblast growth factor 1 (FGF1) is a differentiation and survival factor for neuronal cells both in vitro and in vivo. FGF1 activities can be mediated not only by paracrine and autocrine pathways involving FGF receptors but also by an intracrine pathway, which is an underestimated mode of action. Indeed, FGF1 lacks a secretion signal peptide and contains a nuclear localization sequence (NLS), which is consistent with its usual intracellular and nuclear localization. To progress in the comprehension of the FGF1 intracrine pathway in neuronal cells, we examined the role of the nuclear translocation of FGF1 for its neurotrophic activity as well as for its protective activity against p53-dependent apoptosis. Thus, we have transfected PC12 cells with different FGF1 expression vectors encoding wild type or mutant (Delta NLS) FGF1. This deletion inhibited both FGF1 nuclear translocation and FGF1 neurotrophic activity (including differentiation and serum-free cell survival). We also show that endogenous FGF1 protection of PC12 cells against p53-dependent cell death requires FGF1 nuclear translocation. Strikingly, wild type FGF1 is found interacting with p53, in contrast to the mutant FGF1 deleted of its NLS, suggesting the presence of direct and/or indirect interactions between FGF1 and p53 pathways. Thus, we present evidences that FGF1 may act by a nuclear pathway to induce neuronal differentiation and to protect the cells from apoptosis whether cell death is induced by serum depletion or p53 activation.

  2. p53 dependent apoptosis and cell cycle delay induced by heteroleptic complexes in human cervical cancer cells.

    PubMed

    Sharma, Gunjan; Rana, Nishant Kumar; Singh, Priya; Dubey, Pradeep; Pandey, Daya Shankar; Koch, Biplob

    2017-04-01

    We previously reported synthesis of novel arene ruthenium (Ru) complexes and evaluated their antitumor activity in murine lymphoma (DL) cells. In this present study we further investigated the mechanism of action of two ruthenium complexes [complex 1 (η6-arene)RuCl(2-pcdpm)] and complex 2 (η6-arene)RuCl(4-mtdpm)] in cervical cancer cell line (HeLa). Our studies demonstrate that anticancer property of these two complexes was due to induction of apoptosis through p53 mediated pathway as well as arrest of cells in G2/M phase of cell cycle. It is worth to note that the complexes did not cause any substantial cytotoxic effect on normal cells. Further in comprehensive studies, apoptosis inducing property of both complexes were established in accordance with array of morphological changes ranging from membrane blebbing to formation of apoptotic bodies and followed by DNA fragmentation assay. Furthermore, Flow cytometry by Annexin V/PI staining delineate that complex 1 and 2 have strident impact to induce apoptosis in HeLa cells. The complex 1 and 2 treated cells show increased level of intracellular ROS generation which was preceded by p53 activation. Apoptosis induced by 1 and 2 was preceded by mitochondrial aggregations which were monitored by mitotracker. In addition flow cytometry analysis showed that both complexes also effectively arrest cells at G2/M phase of cell cycle. Western blot, RT-PCR as well as Real Time analysis were used to further confirm that the complexes induced apoptosis in p53 dependent pathway. Thus, our promising results can contribute to the rational design of novel potential anticancer agents. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Bcl6a function is required during optic cup formation to prevent p53-dependent apoptosis and colobomata.

    PubMed

    Lee, Jiwoon; Lee, Bum-Kyu; Gross, Jeffrey M

    2013-09-01

    Mutations in BCOR (Bcl6 corepressor) are found in patients with oculo-facio-cardio-dental (OFCD) syndrome, a congenital disorder affecting visual system development, and loss-of-function studies in zebrafish and Xenopus demonstrate a role for Bcor during normal optic cup development in preventing colobomata. The mechanism whereby BCOR functions during eye development to prevent colobomata is not known, but in other contexts it serves as a transcriptional corepressor that potentiates transcriptional repression by B cell leukemia/lymphoma 6 (BCL6). Here, we have explored the function of the zebrafish ortholog of Bcl6, Bcl6a, during eye development, and our results demonstrate that Bcl6a, like Bcor, is required to prevent colobomata during optic cup formation. Our data demonstrate that Bcl6a acts downstream of Vax1 and Vax2, known regulators of ventral optic cup formation and choroid fissure closure, and that bcl6a is a direct target of Vax2. Together, this regulatory network functions to repress p53 expression and thereby suppress apoptosis in the developing optic cup. Furthermore, our data demonstrate that Bcl6a functions cooperatively with Bcor, Rnf2 and Hdac1 in a common gene regulatory network that acts to repress p53 and prevent colobomata. Together, these data support a model in which p53-dependent apoptosis needs to be tightly regulated for normal optic cup formation and that Bcl6a, Bcor, Rnf2 and Hdac1 activities mediate this regulation.

  4. Calcarea carbonica induces apoptosis in cancer cells in p53-dependent manner via an immuno-modulatory circuit

    PubMed Central

    2013-01-01

    Background Complementary medicines, including homeopathy, are used by many patients with cancer, usually alongside with conventional treatment. However, the molecular mechanisms underneath the anti-cancer effect, if any, of these medicines have still remained unexplored. To this end we attempted to evaluate the efficacy of calcarea carbonica, a homeopathic medicine, as an anti-cancer agent and to delineate the detail molecular mechanism(s) underlying calcerea carbonica-induced tumor regression. Methods To investigate and delineate the underlying mechanisms of calcarea carbonica-induced tumor regression, Trypan blue dye-exclusion test, flow cytometric, Western blot and reverse transcriptase-PCR techniques were employed. Further, siRNA transfections and inhibitor studies were used to validate the involvement of p53 pathway in calcarea carbonica-induced apoptosis in cancer cells. Results Interestingly, although calcarea carbonica administration to Ehrlich’s ascites carcinoma (EAC)- and Sarcoma-180 (S-180)-bearing Swiss albino mice resulted in 30-35% tumor cell apoptosis, it failed to induce any significant cell death in ex vivo conditions. These results prompted us to examine whether calcarea carbonica employs the immuno-modulatory circuit in asserting its anti-tumor effects. Calcarea carbonica prevented tumor-induced loss of effector T cell repertoire, reversed type-2 cytokine bias and attenuated tumor-induced inhibition of T cell proliferation in tumor-bearing host. To confirm the role of immune system in calcarea carbonica-induced cancer cell death, a battery of cancer cells were co-cultured with calcarea carbonica-primed T cells. Our results indicated a "two-step" mechanism of the induction of apoptosis in tumor cells by calcarea carbonica i.e., (1) activation of the immune system of the host; and (2) induction of cancer cell apoptosis via immuno-modulatory circuit in p53-dependent manner by down-regulating Bcl-2:Bax ratio. Bax up-regulation resulted in

  5. The p53-dependent radioadaptive response

    NASA Astrophysics Data System (ADS)

    Ohnishi, Takeo

    We already reported that conditioning exposures at low doses, or at low dose-rates, lowered radiation-induced p53-dependent apoptosis in cultured cells in vitro and in the spleens of mice in vivo. In this study, the aim was to characterize the p53-dependent radioadaptive response at the molecular level. We used wild-type (wt) p53 and mutated (m) p53 containing cells derived from the human lung cancer H1299 cell line, which is p53-null. Cellular radiation sensitivities were determined with a colony-forming assay. The accumulation of p53, Hdm2, and iNOS was analyzed with Western blotting. The quantification of chromosomal aberrations was estimated by scoring dicentrics per cell. In wtp53 cells, it was demonstrated that the lack of p53 accumulation was coupled with the activation of Hdm2 after low dose irradiation (0.02 Gy). Although NO radicals were only minimally induced in wtp53 cells irradiated with a challenging irradiation (6 Gy) alone, NO radicals were seen to increase about 2-4 fold after challenging irradiation following a priming irradiation (0.02 Gy). Under similar irradiation conditions with a priming and challenging irradiation in wtp53 cells, induction of radioresistance and a depression of chromosomal aberrations were observed only in the absence of Pifithrin-α (a p53 inhibitor), RITA or Nutlin-3 (p53-Hdm2 interaction inhibitors), aminoguanidine (an iNOS inhibitor) and c-PTIO (an NO radical scavenger). On the other hand, in p53 dysfunctional cells, a radioadaptive response was not observed in the presence or absence of those inhibitors. Moreover, radioresistance developed when wtp53 cells were treated with ISDN (an NO generating agent) alone. These findings suggest that NO radicals are an initiator of the radioadaptive response acting through the activation of Hdm2 and the depression of p53 accumulations.

  6. Inhibition of Casein kinase-2 induces p53-dependent cell cycle arrest and sensitizes glioblastoma cells to tumor necrosis factor (TNFα)-induced apoptosis through SIRT1 inhibition.

    PubMed

    Dixit, D; Sharma, V; Ghosh, S; Mehta, V S; Sen, E

    2012-02-09

    Glioblastoma multiforme (GBM) are resistant to TNFα-induced apoptosis and blockade of TNFα-induced NF-κB activation sensitizes glioma cells to apoptosis. As Casein kinase-2 (CK2) induces aberrant NF-κB activation and as we observed elevated CK2 levels in GBM tumors, we investigated the potential of CK2 inhibitors (CK2-Is) - DRB and Apigenin in sensitizing glioma cells to TNFα-induced apoptosis. CK2-Is and CK2 small interfering RNA (siRNA) reduced glioma cell viability, inhibited TNFα-mediated NF-κB activation, and sensitized cell to TNFα-induced apoptosis. Importantly, CK2-Is activated p53 function in wild-type but not in p53 mutant cells. Activation of p53 function involved its increased transcriptional activation, DNA-binding ability, increased expression of p53 target genes associated with cell cycle progression and apoptosis. Moreover, CK2-Is decreased telomerase activity and increased senescence in a p53-dependent manner. Apoptotic gene profiling indicated that CK2-Is differentially affect p53 and TNFα targets in p53 wild-type and mutant glioma cells. CK2-I decreased MDM2-p53 association and p53 ubiquitination to enhance p53 levels. Interestingly, CK2-Is downregulated SIRT1 activity and over-expression of SIRT1 decreased p53 transcriptional activity and rescued cells from CK2-I-induced apoptosis. This ability of CK2-Is to sensitize glioma to TNFα-induced death via multiple mechanisms involving abrogation of NF-κB activation, reactivation of wild-type p53 function and SIRT1 inhibition warrants investigation.

  7. Perfluorooctanoic acid induces apoptosis through the p53-dependent mitochondrial pathway in human hepatic cells: a proteomic study.

    PubMed

    Huang, Qingyu; Zhang, Jie; Martin, Francis L; Peng, Siyuan; Tian, Meiping; Mu, Xiaoli; Shen, Heqing

    2013-11-25

    Perfluorooctanoic acid (PFOA) is one of the most commonly used perfluorinated compounds, and exposure to it has been associated with a number of adverse health effects. However, the molecular mechanisms involved in PFOA toxicity are still not well characterized. In the present study, flow cytometry analysis revealed that PFOA induced oxidative stress, cell cycle arrest and apoptosis in human non-tumor hepatic cells (L-02). Furthermore, we investigated the alterations in protein profile within L-02 cells exposed to PFOA, aiming to explore the mechanisms underlying PFOA hepatotoxicity on the proteome level. Of the 28 proteins showing significant differential expression in response to PFOA, 24 were down-regulated and 4 were up-regulated. This proteomic study proposed that the inhibition of some proteins, including GRP78, HSP27, CTSD and hnRNPC may be involved in the activation of p53, which consequently triggered the apoptotic process in L-02 cells. Induction of apoptosis via the p53-dependent mitochondrial pathway is further suggested as one of the key toxicological events occurring in L-02 cells under PFOA stress. We hope these data will shed new light on the molecular mechanisms responsible for PFOA-mediated toxicity in human liver cells, and from such studies useful biomarkers indicative of PFOA exposure could be developed. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Pomegranate protects against arsenic-induced p53-dependent ROS-mediated inflammation and apoptosis in liver cells.

    PubMed

    Choudhury, Sreetama; Ghosh, Sayan; Mukherjee, Sudeshna; Gupta, Payal; Bhattacharya, Saurav; Adhikary, Arghya; Chattopadhyay, Sreya

    2016-12-01

    Molecular mechanisms involved in arsenic-induced toxicity are complex and elusive. Liver is one of the most favored organs for arsenic toxicity as methylation of arsenic occurs mostly in the liver. In this study, we have selected a range of environmentally relevant doses of arsenic to examine the basis of arsenic toxicity and the role of pomegranate fruit extract (PFE) in combating it. Male Swiss albino mice exposed to different doses of arsenic presented marked hepatic injury as evident from histological and electron microscopic studies. Increased activities of enzymes alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and alkaline phosphatase corroborated extensive liver damage. It was further noted that arsenic exposure initiated reactive oxygen species (ROS)-dependent apoptosis in the hepatocytes involving loss of mitochondrial membrane potential. Arsenic significantly increased nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB), coupled with increase in phosphorylated Iκ-B, possibly as adaptive cellular survival strategies. Arsenic-induced oxidative DNA damage to liver cells culminated in p53 activation and increased expression of p53 targets like miR-34a and Bax. Pomegranate polyphenols are known to possess remarkable antioxidant properties and are capable of protecting normal cells from various stimuli-induced oxidative stress and toxicities. We explored the protective role of PFE in ameliorating arsenic-induced hepatic damage. PFE was shown to reduce ROS generation in hepatocytes, thereby reducing arsenic-induced Nrf2 activation. PFE also inhibited arsenic-induced NF-κB-inflammatory pathway. Data revealed that PFE reversed arsenic-induced hepatotoxicity and apoptosis by modulating the ROS/Nrf2/p53-miR-34a axis. For the first time, we have mapped the possible signaling pathways associated with arsenic-induced hepatotoxicity and its rescue by pomegranate polyphenols.

  9. Phenylhydroquinone induces loss of thymocytes through cell cycle arrest and apoptosis elevation in p53-dependent pathway.

    PubMed

    Nakata, Yuichiro; Nishi, Kosuke; Nishimoto, Sogo; Sugahara, Takuya

    2013-01-01

    ortho-Phenylphenol has been employed in post-harvest treatment of citrus fruits. Although o-phenylphenol has been reported to cause carcinomas in the urinary tract in rats, toxicity to the immune organs is still unknown. Herein, we report that administration of o-phenylphenol induces thymic atrophy and loss of thymocytes in female BALB/c mice. The influence seems to result from inhibition of the thymocyte development, because increased and decreased populations of the CD4⁻ CD8⁻ double-negative and CD4⁺ CD8⁺ double-positive thymocytes were observed in the o-phenylphenol-administered mice, respectively. ortho-Phenylphenol is metabolized to phenylhydroquinone by cytochrome P450 monooxygenases. Phenylhydroquinone made cell cycle of thymocytes to be arrested through reduced expression of the genes associated with G₂/M phase and through phosphorylation of p53 at Ser15. Phosphorylation of p53 at Ser15 was upregulated by activation of not only ATR but also Erk1/2 and p38, leading to increase of apoptosis. Gene expression of cytochrome P450 1A1 (CYP1A1) was promoted in thymocytes from the o-phenylphenol-administered mice. Overall, our results suggest that o-phenylphenol induces CYP1A1 expression and is metabolized into phenylhydroquinone by the expressed CYP1A1 in thymocytes. The produced phenylhydroquinone in turn induces inhibition of thymocyte development through cell cycle arrest and apoptosis in the p53-dependent pathway.

  10. PEG-b-PCL polymeric nano-micelle inhibits vascular angiogenesis by activating p53-dependent apoptosis in zebrafish.

    PubMed

    Zhou, Tian; Dong, Qinglei; Shen, Yang; Wu, Wei; Wu, Haide; Luo, Xianglin; Liao, Xiaoling; Wang, Guixue

    Micro/nanoparticles could cause adverse effects on cardiovascular system and increase the risk for cardiovascular disease-related events. Nanoparticles prepared from poly(ethylene glycol) (PEG)-b-poly(ε-caprolactone) (PCL), namely PEG-b-PCL, a widely studied biodegradable copolymer, are promising carriers for the drug delivery systems. However, it is unknown whether polymeric PEG-b-PCL nano-micelles give rise to potential complications of the cardiovascular system. Zebrafish were used as an in vivo model to evaluate the effects of PEG-b-PCL nano-micelle on cardiovascular development. The results showed that PEG-b-PCL nano-micelle caused embryo mortality as well as embryonic and larval malformations in a dose-dependent manner. To determine PEG-b-PCL nano-micelle effects on embryonic angiogenesis, a critical process in zebrafish cardiovascular development, growth of intersegmental vessels (ISVs) and caudal vessels (CVs) in flk1-GFP transgenic zebrafish embryos using fluorescent stereomicroscopy were examined. The expression of fetal liver kinase 1 (flk1), an angiogenic factor, by real-time quantitative polymerase chain reaction (qPCR) and in situ whole-mount hybridization were also analyzed. PEG-b-PCL nano-micelle decreased growth of ISVs and CVs, as well as reduced flk1 expression in a concentration-dependent manner. Parallel to the inhibitory effects on angiogenesis, PEG-b-PCL nano-micelle exposure upregulated p53 pro-apoptotic pathway and induced cellular apoptosis in angiogenic regions by qPCR and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay. This study further showed that inhibiting p53 activity, either by pharmacological inhibitor or RNA interference, could abrogate the apoptosis and angiogenic defects caused by PEG-b-PCL nano-micelles, indicating that PEG-b-PCL nano-micelle inhibits angiogenesis by activating p53-mediated apoptosis. This study indicates that polymeric PEG-b-PCL nano-micelle could pose potential hazards

  11. PEG-b-PCL polymeric nano-micelle inhibits vascular angiogenesis by activating p53-dependent apoptosis in zebrafish

    PubMed Central

    Zhou, Tian; Dong, Qinglei; Shen, Yang; Wu, Wei; Wu, Haide; Luo, Xianglin; Liao, Xiaoling; Wang, Guixue

    2016-01-01

    Micro/nanoparticles could cause adverse effects on cardiovascular system and increase the risk for cardiovascular disease-related events. Nanoparticles prepared from poly(ethylene glycol) (PEG)-b-poly(ε-caprolactone) (PCL), namely PEG-b-PCL, a widely studied biodegradable copolymer, are promising carriers for the drug delivery systems. However, it is unknown whether polymeric PEG-b-PCL nano-micelles give rise to potential complications of the cardiovascular system. Zebrafish were used as an in vivo model to evaluate the effects of PEG-b-PCL nano-micelle on cardiovascular development. The results showed that PEG-b-PCL nano-micelle caused embryo mortality as well as embryonic and larval malformations in a dose-dependent manner. To determine PEG-b-PCL nano-micelle effects on embryonic angiogenesis, a critical process in zebrafish cardiovascular development, growth of intersegmental vessels (ISVs) and caudal vessels (CVs) in flk1-GFP transgenic zebrafish embryos using fluorescent stereomicroscopy were examined. The expression of fetal liver kinase 1 (flk1), an angiogenic factor, by real-time quantitative polymerase chain reaction (qPCR) and in situ whole-mount hybridization were also analyzed. PEG-b-PCL nano-micelle decreased growth of ISVs and CVs, as well as reduced flk1 expression in a concentration-dependent manner. Parallel to the inhibitory effects on angiogenesis, PEG-b-PCL nano-micelle exposure upregulated p53 pro-apoptotic pathway and induced cellular apoptosis in angiogenic regions by qPCR and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay. This study further showed that inhibiting p53 activity, either by pharmacological inhibitor or RNA interference, could abrogate the apoptosis and angiogenic defects caused by PEG-b-PCL nano-micelles, indicating that PEG-b-PCL nano-micelle inhibits angiogenesis by activating p53-mediated apoptosis. This study indicates that polymeric PEG-b-PCL nano-micelle could pose potential hazards

  12. Eriocalyxin B induces apoptosis and cell cycle arrest in pancreatic adenocarcinoma cells through caspase- and p53-dependent pathways

    SciTech Connect

    Li, Lin; Yue, Grace G.L.; Lau, Clara B.S.; Sun, Handong; Fung, Kwok Pui; Leung, Ping Chung; Han, Quanbin; Leung, Po Sing

    2012-07-01

    Pancreatic cancer is difficult to detect early and responds poorly to chemotherapy. A breakthrough in the development of new therapeutic agents is urgently needed. Eriocalyxin B (EriB), isolated from the Isodon eriocalyx plant, is an ent-kaurane diterpenoid with promise as a broad-spectrum anti-cancer agent. The anti-leukemic activity of EriB, including the underlying mechanisms involved, has been particularly well documented. In this study, we demonstrated for the first time EriB's potent cytotoxicity against four pancreatic adenocarcinoma cell lines, namely PANC-1, SW1990, CAPAN-1, and CAPAN-2. The effects were comparable to that of the chemotherapeutic camptothecin (CAM), but with much lower toxicity against normal human liver WRL68 cells. EriB's cytoxicity against CAPAN-2 cells was found to involve caspase-dependent apoptosis and cell cycle arrest at the G2/M phase. Moreover, the p53 pathway was found to be activated by EriB in these cells. Furthermore, in vivo studies showed that EriB inhibited the growth of human pancreatic tumor xenografts in BALB/c nude mice without significant secondary adverse effects. These results suggest that EriB should be considered a candidate for pancreatic cancer treatment. -- Highlights: ► We study Eriocalyxin B (EriB)'s cytotoxic effects on pancreatic cancer cell lines. ► EriB inhibits cell proliferation via mediation of apoptosis and cell cycle arrest. ► The effects are involved in caspase-dependent apoptosis and p53 pathway. ► In vivo study also shows EriB inhibits the growth of human pancreatic tumor. ► EriB can be a good candidate for chemotherapy in pancreatic cancer.

  13. AATF/Che-1 acts as a phosphorylation-dependent molecular modulator to repress p53-driven apoptosis

    PubMed Central

    Höpker, Katja; Hagmann, Henning; Khurshid, Safiya; Chen, Shuhua; Hasskamp, Pia; Seeger-Nukpezah, Tamina; Schilberg, Katharina; Heukamp, Lukas; Lamkemeyer, Tobias; Sos, Martin L; Thomas, Roman K; Lowery, Drew; Roels, Frederik; Fischer, Matthias; Liebau, Max C; Resch, Ulrike; Kisner, Tülay; Röther, Fabian; Bartram, Malte P; Müller, Roman Ulrich; Fabretti, Francesca; Kurschat, Peter; Schumacher, Björn; Gaestel, Matthias; Medema, René H; Yaffe, Michael B; Schermer, Bernhard; Reinhardt, H Christian; Benzing, Thomas

    2012-01-01

    Following genotoxic stress, cells activate a complex signalling network to arrest the cell cycle and initiate DNA repair or apoptosis. The tumour suppressor p53 lies at the heart of this DNA damage response. However, it remains incompletely understood, which signalling molecules dictate the choice between these different cellular outcomes. Here, we identify the transcriptional regulator apoptosis-antagonizing transcription factor (AATF)/Che-1 as a critical regulator of the cellular outcome of the p53 response. Upon genotoxic stress, AATF is phosphorylated by the checkpoint kinase MK2. Phosphorylation results in the release of AATF from cytoplasmic MRLC3 and subsequent nuclear translocation where AATF binds to the PUMA, BAX and BAK promoter regions to repress p53-driven expression of these pro-apoptotic genes. In xenograft experiments, mice exhibit a dramatically enhanced response of AATF-depleted tumours following genotoxic chemotherapy with adriamycin. The exogenous expression of a phospho-mimicking AATF point mutant results in marked adriamycin resistance in vivo. Nuclear AATF enrichment appears to be selected for in p53-proficient endometrial cancers. Furthermore, focal copy number gains at the AATF locus in neuroblastoma, which is known to be almost exclusively p53-proficient, correlate with an adverse prognosis and reduced overall survival. These data identify the p38/MK2/AATF signalling module as a critical repressor of p53-driven apoptosis and commend this pathway as a target for DNA damage-sensitizing therapeutic regimens. PMID:22909821

  14. Neuropeptide Y protects kidney against cisplatin-induced nephrotoxicity by regulating p53-dependent apoptosis pathway.

    PubMed

    Kim, Namoh; Min, Woo-Kie; Park, Min Hee; Lee, Jong Kil; Jin, Hee Kyung; Bae, Jae-Sung

    2016-05-01

    Cisplatin is a platinum-based chemotherapeutic drug for treating various types of cancers. However, the use of cisplatin is limited by its negative effect on normal tissues, particularly nephrotoxicity. Various mechanisms such as DNA adduct formation, mitochondrial dysfunction, oxidative stress, and apoptosis are involved in the adverse effect induced by cisplatin treatment. Several studies have suggested that neuropeptide Y (NPY) is involved in neuroprotection as well as restoration of bone marrow dysfunction from chemotherapy induced nerve injury. However, the role of NPY in chemotherapy- induced nephrotoxicity has not been studied. Here, we show that NPY rescues renal dysfunction by reducing the expression of pro-apoptotic proteins in cisplatin induced nephrotoxicity through Y1 receptor, suggesting that NPY can protect kidney against cisplatin nephrotoxicity as a possible useful agent to prevent and treat cisplatin-induced nephrotoxicity. [BMB Reports 2016; 49(5): 288-292].

  15. Essential role of caspase-8 in p53/p73-dependent apoptosis induced by etoposide in head and neck carcinoma cells

    PubMed Central

    2011-01-01

    Background Caspase-8 is a key upstream mediator in death receptor-mediated apoptosis and also participates in mitochondria-mediated apoptosis via cleavage of proapoptotic Bid. However, the role of caspase-8 in p53- and p73-dependent apoptosis induced by genotoxic drugs remains unclear. We recently reported that the reconstitution of procaspase-8 is sufficient for sensitizing cisplatin- but not etoposide-induced apoptosis, in chemoresistant and caspase-8 deficient HOC313 head and neck squamous cell carcinoma (HNSCC) cells. Results We show that p53/p73-dependent caspase-8 activation is required for sensitizing etoposide-induced apoptosis by utilizing HOC313 cells carrying a temperature-sensitive p53G285K mutant. Restoration of wild-type p53 function under the permissive conditions, together with etoposide treatment, led to substantial transcriptional activation of proapoptotic Noxa and PUMA, but failed to induce apoptosis. In addition to p53 restoration, caspase-8 reconstitution was needed for sensitization to etoposide-induced apoptosis, mitochondria depolarization, and cleavage of the procaspases-3, and -9. In etoposide-sensitive Ca9-22 cells carrying a temperature-insensitive mutant p53, siRNA-based p73 knockdown blocked etoposide-induced apoptosis and procaspase-8 cleavage. However, induction of p73 protein and up-regulation of Noxa and PUMA, although observed in Ca9-22 cells, were hardly detected in etoposide-treated HOC313 cells under non-permissive conditions, suggesting a contribution of p73 reduction to etoposide resistance in HOC313 cells. Finally, the caspase-9 inhibitor Ac-LEHD-CHO or caspase-9 siRNA blocked etoposide-induced caspase-8 activation, Bid cleavage, and apoptosis in both cell lines, indicating that p53/p73-dependent caspase-8 activation lies downstream of mitochondria. Conclusions we conclude that p53 and p73 can act as upstream regulators of caspase-8, and that caspase-8 is an essential mediator of the p53/p73-dependent apoptosis induced by

  16. Induction of apoptosis by cytoplasmically localized wild-type p53 and the S121F mutant super p53

    PubMed Central

    YASUDA, KATSUHIRO; KATO, SHUNSUKE; SAKAMOTO, YASUHIRO; WATANABE, GOU; MASHIKO, SATSUKI; SATO, ATSUKO; KAKUDO, YUICHI; ISHIOKA, CHIKASHI

    2012-01-01

    After DNA damage, p53 is accumulated in the nucleus and transactivates downstream genes and induces apoptosis. There are two pathways in p53-dependent apoptosis, the transactivation-dependent and -independent pathway. In this study, we constructed p53-inducible glioblastoma cell lines and analyzed them for the induction of apoptosis and transactivation of p53-downstream genes after the nuclear or cytoplasmic expression of p53. To sequester p53 in the cytoplasm, we used p53 mutant with arginine to glycine substitution at residue 306 (R306G). Wild-type p53 retained the ability to arrest the cell cycle, and a p53 mutant with serine to phenylalanine substitution at residue 121 (S121F), which has a strong ability to induce apoptosis, retained this ability even when both the wild-type and p53 and S121F mutant were exclusively sequestered from the nucleus into the cytoplasm. Notably, cytoplasmically sequestered wild-type p53 and S121F mutant transactivated the downstream genes with distinct expression profiles, and the strong apoptotic ability of S121F was not associated with its transactivation activity. These results underscore the existence of transactivation-independent apoptosis and cytoplasmic function of p53. PMID:22783376

  17. MG132 plus apoptosis antigen-1 (APO-1) antibody cooperate to restore p53 activity inducing autophagy and p53-dependent apoptosis in HPV16 E6-expressing keratinocytes.

    PubMed

    Lagunas-Martínez, Alfredo; García-Villa, Enrique; Arellano-Gaytán, Magaly; Contreras-Ochoa, Carla O; Dimas-González, Jisela; López-Arellano, María E; Madrid-Marina, Vicente; Gariglio, Patricio

    2017-01-01

    The E6 oncoprotein can interfere with the ability of infected cells to undergo programmed cell death through the proteolytic degradation of proapoptotic proteins such as p53, employing the proteasome pathway. Therefore, inactivation of the proteasome through MG132 should restore the activity of several proapoptotic proteins. We investigated whether in HPV16 E6-expressing keratinocytes (KE6 cells), the restoration of p53 levels mediated by MG132 and/or activation of the CD95 pathway through apoptosis antigen-1 (APO-1) antibody are responsible for the induction of apoptosis. We found that KE6 cells underwent apoptosis mainly after incubation for 24 h with MG132 alone or APO-1 plus MG132. Both treatments activated the extrinsic and intrinsic apoptosis pathways. Autophagy was also activated, principally by APO-1 plus MG132. Inhibition of E6-mediated p53 proteasomal degradation by MG132 resulted in the elevation of p53 protein levels and its phosphorylation in Ser46 and Ser20; the p53 protein was localized mainly at nucleus after treatment with MG132 or APO-1 plus MG132. In addition, induction of its transcriptional target genes such as p21, Bax and TP53INP was observed 3 and 6 h after treatment. Also, LC3 mRNA was induced after 3 and 6 h, which correlates with lipidation of LC3B protein and induction of autophagy. Finally, using pifithrin alpha we observed a decrease in apoptosis induced by MG132, and by APO-1 plus MG132, suggesting that restoration of APO-1 sensitivity occurs in part through an increase in both the levels and the activity of p53. The use of small molecules to inhibit the proteasome pathway might permit the activation of cell death, providing new opportunities for CC treatment.

  18. Long noncoding RNA lincRNA-p21 is the major mediator of UVB-induced and p53-dependent apoptosis in keratinocytes

    PubMed Central

    Hall, J R; Messenger, Z J; Tam, H W; Phillips, S L; Recio, L; Smart, R C

    2015-01-01

    LincRNA-p21 is a long noncoding RNA and a transcriptional target of p53 and HIF-1α. LincRNA-p21 regulates gene expression in cis and trans, mRNA translation, protein stability, the Warburg effect, and p53-dependent apoptosis and cell cycle arrest in doxorubicin-treated mouse embryo fibroblasts. p53 plays a key role in the response of skin keratinocytes to UVB-induced DNA damage by inducing cell cycle arrest and apoptosis. In skin cancer development, UVB-induced mutation of p53 allows keratinocytes upon successive UVB exposures to evade apoptosis and cell cycle arrest. We hypothesized that lincRNA-p21 has a key functional role in UVB-induced apoptosis and/or cell cycle arrest in keratinocytes and loss of lincRNA-p21 function results in the evasion of apoptosis and/or cell cycle arrest. We observed that lincRNA-p21 transcripts are highly inducible by UVB in mouse and human keratinocytes in culture and in mouse skin in vivo. LincRNA-p21 is regulated at the transcriptional level in response to UVB, and the UVB induction of lincRNA-p21 in keratinocytes and in vivo in mouse epidermis is primarily through a p53-dependent pathway. Knockdown of lincRNA-p21 blocked UVB-induced apoptosis in mouse and human keratinocytes, and lincRNA-p21 was responsible for the majority of UVB-induced and p53-mediated apoptosis in keratinocytes. Knockdown of lincRNA-p21 had no effect on cell proliferation in untreated or UVB-treated keratinocytes. An early event in skin cancer is the mutation of a single p53 allele. We observed that a mutant p53+/R172H allele expressed in mouse epidermis (K5Cre+/tg;LSLp53+/R172H) showed a significant dominant-negative inhibitory effect on UVB-induced lincRNA-p21 transcription and apoptosis in epidermis. We conclude lincRNA-p21 is highly inducible by UVB and has a key role in triggering UVB-induced apoptotic death. We propose that the mutation of a single p53 allele provides a pro-oncogenic function early in skin cancer development through a dominant

  19. Identification of epigallocatechin-3-gallate in green tea polyphenols as a potent inducer of p53-dependent apoptosis in the human lung cancer cell line A549.

    PubMed

    Yamauchi, Rieko; Sasaki, Kaori; Yoshida, Kenichi

    2009-08-01

    The effects of green tea polyphenols on cultured cancer cells have been well characterized, especially the effects of epigallocatechin-3-gallate (EGCg), since EGCg suppresses oncogenic signaling pathways and induces cell cycle arrest or apoptosis by regulating cell cycle-associated proteins. In the present study, we attempted to identify signaling pathways or target molecules regulated by each of or a mixture of green tea polyphenols, including epicatechin (EC), epicatechin-3-gallate (ECg), epigallocatechin (EGC), and EGCg, in the human lung cancer cell line A549. ECg, EGC, and a catechin mixture, in addition to EGCg, significantly decreased cell viability. In contrast, caspase 3/7 activity, an apoptosis indicator, was specifically induced by EGCg. By conducting a series of luciferase-based reporter assays, we revealed that the catechin mixture only up-regulates the p53 reporter. EGCg was a more potent inducer of p53-dependent transcription, and this induction was further supported by the induced level of p53 protein. RNA interference (RNAi)-mediated p53 knockdown completely abolished EGCg-induced apoptosis. Finally, a proteome and western blot analysis using approximately 70 different antibodies failed to detect up-regulated proteins in catechin mixture-treated A549 cells. Taken together, these results indicate that EGCg, among several green tea polyphenols, is a potent apoptosis inducer that functions exclusively through a p53-dependent pathway in A549 cells.

  20. p53-dependent ceramide response to genotoxic stress.

    PubMed Central

    Dbaibo, G S; Pushkareva, M Y; Rachid, R A; Alter, N; Smyth, M J; Obeid, L M; Hannun, Y A

    1998-01-01

    Both p53 and ceramide have been implicated in the regulation of growth suppression. p53 has been proposed as the "guardian of the genome" and ceramide has been suggested as a "tumor suppressor lipid. " Both molecules appear to regulate cell cycle arrest, senescence, and apoptosis. In this study, we investigated the relationship between p53 and ceramide. We found that treatment of Molt-4 cells with low concentrations of actinomycin D or gamma-irradiation, which activate p53-dependent apoptosis, induces apoptosis only in cells expressing normal levels of p53. In these cells, p53 activation was followed by a dose- and time-dependent increase in endogenous ceramide levels which was not seen in cells lacking functional p53 and treated similarly. Similar results were seen in irradiated L929 cells whereby the p53-deficient clone was significantly more resistant to irradiation and exhibited no ceramide response. However, in p53-independent systems, such as growth suppression induced by TNF-alpha or serum deprivation, ceramide accumulated irrespective of the upregulation of p53, indicating that p53 regulates ceramide accumulation in only a subset of growth-suppressive pathways. Finally, ceramide did not increase p53 levels when used at growth-suppressive concentrations. Also, when cells lacking functional p53, either due to mutation or the expression of the E6 protein of human papilloma virus, were treated with exogenous ceramide, there was equal growth suppression, cell cycle arrest, and apoptosis as compared with cells expressing normal p53. These results indicate that p53 is unlikely to function "downstream" of ceramide. Instead, they suggest that, in situations where p53 performs a critical regulatory role, such as the response to genotoxic stress, it functions "upstream" of ceramide. These studies begin to define a relationship between these two pathways of growth inhibition. PMID:9664074

  1. The dependence receptor Ret induces apoptosis in somatotrophs through a Pit-1/p53 pathway, preventing tumor growth

    PubMed Central

    Cañibano, Carmen; Rodriguez, Noela L; Saez, Carmen; Tovar, Sulay; Garcia-Lavandeira, Montse; Borrello, Maria Grazia; Vidal, Anxo; Costantini, Frank; Japon, Miguel; Dieguez, Carlos; Alvarez, Clara V

    2007-01-01

    Somatotrophs are the only pituitary cells that express Ret, GFRα1 and GDNF. This study investigated the effects of Ret in a somatotroph cell line, in primary pituitary cultures and in Ret KO mice. Ret regulates somatotroph numbers by inducing Pit-1 overexpression, leading to increased p53 expression and apoptosis, both of which can be prevented with Ret or Pit-1 siRNA. The Pit-1 overexpression is mediated by sustained activation of PKCδ, JNK, c/EBPα and CREB induced by a complex of Ret, caspase 3 and PKCδ. In the presence of GDNF, Akt is activated, and the Pit-1 overexpression and resulting apoptosis are blocked. The adenopituitary of Ret KO mice is larger than normal, showing Pit-1 and somatotroph hyperplasia. In normal animals, activation of the Ret/Pit-1/p53 pathway by retroviral introduction of Ret blocked tumor growth in vivo. Thus, somatotrophs have an intrinsic mechanism for controlling Pit-1/GH production through an apoptotic/survival pathway. Ret might be of value for treatment of pituitary adenomas. PMID:17380130

  2. The dependence receptor Ret induces apoptosis in somatotrophs through a Pit-1/p53 pathway, preventing tumor growth.

    PubMed

    Cañibano, Carmen; Rodriguez, Noela L; Saez, Carmen; Tovar, Sulay; Garcia-Lavandeira, Montse; Borrello, Maria Grazia; Vidal, Anxo; Costantini, Frank; Japon, Miguel; Dieguez, Carlos; Alvarez, Clara V

    2007-04-18

    Somatotrophs are the only pituitary cells that express Ret, GFRalpha1 and GDNF. This study investigated the effects of Ret in a somatotroph cell line, in primary pituitary cultures and in Ret KO mice. Ret regulates somatotroph numbers by inducing Pit-1 overexpression, leading to increased p53 expression and apoptosis, both of which can be prevented with Ret or Pit-1 siRNA. The Pit-1 overexpression is mediated by sustained activation of PKCdelta, JNK, c/EBPalpha and CREB induced by a complex of Ret, caspase 3 and PKCdelta. In the presence of GDNF, Akt is activated, and the Pit-1 overexpression and resulting apoptosis are blocked. The adenopituitary of Ret KO mice is larger than normal, showing Pit-1 and somatotroph hyperplasia. In normal animals, activation of the Ret/Pit-1/p53 pathway by retroviral introduction of Ret blocked tumor growth in vivo. Thus, somatotrophs have an intrinsic mechanism for controlling Pit-1/GH production through an apoptotic/survival pathway. Ret might be of value for treatment of pituitary adenomas.

  3. New orally active DNA minor groove binding small molecule CT-1 acts against breast cancer by targeting tumor DNA damage leading to p53-dependent apoptosis.

    PubMed

    Saini, Karan Singh; Hamidullah; Ashraf, Raghib; Mandalapu, Dhanaraju; Das, Sharmistha; Siddiqui, Mohd Quadir; Dwivedi, Sonam; Sarkar, Jayanta; Sharma, Vishnu Lal; Konwar, Rituraj

    2017-04-01

    Targeting tumor DNA damage and p53 pathway is a clinically established strategy in the development of cancer chemotherapeutics. Majority of anti-cancer drugs are delivered through parenteral route for reasons like severe toxicity, lack of stability, and poor enteral absorption. Current DNA targeting drugs in clinical like anthracycline suffers from major drawbacks like cardiotoxicity. Here, we report identification of a new orally active small molecule curcumin-triazole conjugate (CT-1) with significant anti-breast cancer activity in vitro and in vivo. CT-1 selectively and significantly inhibits viability of breast cancer cell lines; retards cells cycle progression at S phase and induce mitochondrial-mediated cell apoptosis. CT-1 selectively binds to minor groove of DNA and induces DNA damage leading to increase in p53 along with decrease in its ubiquitination. Inhibition of p53 with pharmacological inhibitor as well as siRNA revealed the necessity of p53 in CT-1-mediated anti-cancer effects in breast cancer cells. Studies using several other intact p53 and deficient p53 cancer cell lines further confirmed necessity of p53 in CT-1-mediated anti-cancer response. Pharmacological inhibition of pan-caspase showed CT-1 induces caspase-dependent cell death in breast cancer cells. Most interestingly, oral administration of CT-1 induces significant inhibition of tumor growth in LA-7 syngeneic orthotropic rat mammary tumor model. CT-1 treated mammary tumor shows enhancement in DNA damage, p53 upregulation, and apoptosis. Collectively, CT-1 exhibits potent anti-cancer effect both in vitro and in vivo and could serve as a safe orally active lead for anti-cancer drug development. © 2016 Wiley Periodicals, Inc.

  4. miRNA‑504 inhibits p53dependent vascular smooth muscle cell apoptosis and may prevent aneurysm formation.

    PubMed

    Cao, Xue; Cai, Zhenguo; Liu, Junyan; Zhao, Yanru; Wang, Xin; Li, Xueqi; Xia, Hongyuan

    2017-09-01

    Abdominal aortic aneurysm (AAA) is a common disease that is associated with the proliferation and apoptosis of vascular smooth muscle cells (VSMCs). VSMCs are regulated by microRNAs (miRNA). The aim of the present study was to identify miRNA sequences that regulate aortic SMCs during AAA. miRNA‑504 was identified using a miRNA PCR array and by reverse transcription‑quantitative polymerase chain reaction analysis, and its expression levels were observed to be downregulated in the aortic cells derived from patients with AAA when compared with controls. Transfection of SMCs with pMSCV‑miRNA‑504 vector was performed, and cell proliferation and the expression levels of proliferating cell nuclear antigen (PCNA), replication factor C subunit 4 (RFC4), B‑cell lymphoma‑2 (Bcl‑2) and caspase‑3/9 were measured by western blotting. The mechanisms underlying the effects of miRNA‑504 was then analyzed. The results demonstrated that overexpression of miRNA‑504 significantly upregulated the expression levels of PCNA, RFC4 and Bcl‑2, while caspase‑3/9 expression was significantly inhibited when compared with non‑targeting controls. In addition, miRNA‑504 overexpression was observed to promote the proliferation of SMCs. The expression level of the tumor suppressor, p53, which is known to be a direct target of miRNA‑504, was inhibited following transfection of SMCs with pMSCV‑miRNA‑504. In addition, the expression of the downstream targets of p53, p21 and Bcl‑like protein‑4, were significantly reduced following overexpression of miRNA‑504. These results revealed the anti‑apoptotic role of miRNA‑504 in SMCs derived from patients with AAA via direct targeting of p53.

  5. Methotrexate induces apoptosis through p53/p21-dependent pathway and increases E-cadherin expression through downregulation of HDAC/EZH2.

    PubMed

    Huang, Wen-Yu; Yang, Pei-Ming; Chang, Yu-Fan; Marquez, Victor E; Chen, Ching-Chow

    2011-02-15

    Methotrexate (MTX) is a dihydrofolate reductase (DHFR) inhibitor widely used as an anticancer drug in different kinds of human cancers. Here we investigated the anti-tumor mechanism of MTX against non-small cell lung cancer (NSCLC) A549 cells. MTX not only inhibited in vitro cell growth via induction of apoptosis, but also inhibited tumor formation in animal xenograft model. RNase protection assay (RPA) and RT-PCR demonstrated its induction of p53 target genes including DR5, p21, Puma and Noxa. Moreover, MTX promoted p53 phosphorylation at Ser15 and acetylaion at Lys373/382, which increase its stability and expression. The apoptosis and inhibition of cell viability induced by MTX were dependent on p53 and, partially, on p21. In addition, MTX also increased E-cadherin expression through inhibition of histone deacetylase (HDAC) activity and downregulation of polycomb group protein enhancer of zeste homologue 2 (EZH2). Therefore, the anticancer mechanism of MTX acts through initiation of p53-dependent apoptosis and restoration of E-cadherin expression by downregulation of HDAC/EZH2.

  6. An anthraquinone derivative from Luffa acutangula induces apoptosis in human lung cancer cell line NCI-H460 through p53-dependent pathway.

    PubMed

    Vanajothi, Ramar; Srinivasan, Pappu

    2016-01-01

    The current study was designed to evaluate the in vitro antiproliferative activity of 1,8-dihydroxy-4-methylanthracene-9,10-dione (DHMA) isolated from the Luffa acutangula against human non-small cell lung cancer cell line (NCI-H460). Induction of apoptosis and reactive oxygen species (ROS) generation was determined through fluorescence microscopic technique. Quantitative real-time PCR and western blotting analysis was carried out to detect the expression of pro-apoptotic (p53, p21, caspase-3, Bax, GADD45A, and ATM) and anti-apoptotic (NF-κB) proteins in NCI-H460 cell line. In silico studies also performed to predict the binding mechanism of DHMA with MDM2-p53 protein. The DHMA inhibited the cell viability of NCI-H460 cells in a dose-dependent manner with an IC(50) of about 50 µg/ml. It significantly reduced cell viability correlated with induction of apoptosis, which was associated with ROS generation. The apoptotic cell death was further confirmed through dual staining and DNA fragmentation assay. DHMA significantly increased the expression of anti-apoptotic protein such as p53, p21, Bax, and caspase-3 but downregulated the expression of NF-κB in NCI-H460 cell line. In silico studies demonstrate that DHMA formed hydrogen bond interaction with key residues Trp26, Phe55 and Lys24 by which it disrupt the binding of p53 with MDM2 receptor. These findings suggested that DHMA induces apoptosis in NCI-H460 via a p53-dependent pathway. This the first study on cytotoxic and apoptosis inducing activity of DHMA from L. acutangula against NCI-H460 cell line. Therefore, DHMA has therapeutic potential for lung cancer treatment.

  7. p53-independent death and p53-induced protection against apoptosis in fibroblasts treated with chemotherapeutic drugs.

    PubMed Central

    Malcomson, R. D.; Oren, M.; Wyllie, A. H.; Harrison, D. J.

    1995-01-01

    Many recent studies have implicated p53 in the cellular response to injury and induction of cell death by apoptosis. In a rat embryonal fibroblast cell line transformed with c-Ha-ras and a mutant temperature-sensitive p53 (val135), cells were G1 arrested at the permissive temperature of 32 degrees C when overexpressed p53 was in wild-type conformation. In this state cells were resistant to apoptosis induced by etoposide (at up to 50 microM) or bleomycin (15 microU ml-1). Cells at 37 degrees C with overexpressed p53 in mutant conformation were freed from this growth arrest, continued proliferating and showed dose-dependent increases in apoptosis. This death is independent of wild-type p53 function. Control cells containing a non-temperature-sensitive mutant p53 (phe132) were sensitive to both etoposide and bleomycin after 24 h at 32 degrees C and 37 degrees C, indicating that the results are not simply due to temperature effects on pharmacokinetics or DNA damage. Our data show that induction of a stable p53-mediated growth arrest renders these cells much less likely to undergo apoptosis in response to certain anti-cancer drugs, and we conclude that the regulatory role of p53 in apoptosis is influenced by the particular cellular context in which this gene is expressed. PMID:7547247

  8. Apoptosis of Sertoli cells after conditional ablation of murine double minute 2 (Mdm2) gene is p53-dependent and results in male sterility

    PubMed Central

    Fouchécourt, S; Livera, G; Messiaen, S; Fumel, B; Parent, A-S; Marine, J-C; Monget, P

    2016-01-01

    Beside its well-documented role in carcinogenesis, the function of p53 family has been more recently revealed in development and female reproduction, but it is still poorly documented in male reproduction. We specifically tested this possibility by ablating Mdm2, an E3 ligase that regulates p53 protein stability and transactivation function, specifically in Sertoli cells (SCs) using the AMH-Cre line and created the new SC-Mdm2−/− line. Heterozygous SC-Mdm2−/+ adult males were fertile, but SC-Mdm2−/− males were infertile and exhibited: a shorter ano-genital distance, an extra duct along the vas deferens that presents a uterus-like morphology, degenerated testes with no organized seminiferous tubules and a complete loss of differentiated germ cells. In adults, testosterone levels as well as StAR, P450c17 (Cyp17a1) and P450scc (Cyp11a1) mRNA levels decreased significantly, and both plasma LH and FSH levels increased. A detailed investigation of testicular development indicated that the phenotype arose during fetal life, with SC-Mdm2−/− testes being much smaller at birth. Interestingly, Leydig cells remained present until adulthood and fetal germ cells abnormally initiated meiosis. Inactivation of Mdm2 in SCs triggered p53 activation and apoptosis as early as 15.5 days post conception with significant increase in apoptotic SCs. Importantly, testis development occurred normally in SC-Mdm2−/− lacking p53 mice (SC-Mdm2−/−p53−/−) and accordingly, these mice were fertile indicating that the aforementioned phenotypes are entirely p53-dependent. These data not only highlight the importance of keeping p53 in check for proper testicular development and male fertility but also certify the critical role of SCs in the maintenance of meiotic repression. PMID:26470726

  9. Brahma-related gene 1 induces apoptosis in a p53-dependent manner in human rheumatoid fibroblast-like synoviocyte MH7A

    PubMed Central

    Hou, Hongli; Xing, Weipeng; Li, Wuyin

    2016-01-01

    Abstract Blocked apoptosis and aggressive inflammatory responses occur in fibroblast-like synoviocyte (FLS) of rheumatoid arthritis (RA) patients. Although Brahma-related gene 1 (BRG1) is considered as a tumor suppressor, few research covers its role in RA. This study aims to reveal effects and potential mechanisms of BRG1 in human FLS cell line MH7A. BRG1 expression in MH7A cells was altered by transfection of overexpression vectors or short hairpin RNAs (shRNAs). Cell viability and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry after transfection. Factors involved in inflammation and apoptosis were quantified by qPCR and Western blot. The interaction between BRG1 and p53 was assessed by immunoprecipitation (IP). Results showed that BRG1 overexpression significantly suppressed MH7A cell viability and induced apoptosis (P < 0.01), and its knockdown had opposite effects. BRG1 reduced mRNA levels of matrix metallopeptidase 3, TIMP metallopeptidase inhibitor 2, cyclooxygenase 2, and interleukin 6, implying its suppressive effects on inflammation. BRG1 interacted with and promoted p53 (P < 0.05). B-cell chronic lymphocytic leukemia/lymphoma 2 was suppressed (P < 0.05), while cytochrome c, caspase 3 (CASP3) and CASP9 were activated (P < 0.01) by BRG1. However, the regulation on these factors was abrogated by p53 knockdown (P < 0.01). These findings suggest that BRG1 may induce apoptosis and suppress inflammation in MH7A cells. Potential functional mechanisms involve the regulation of apoptotic factors by BRG1, which may depend on the recruitment and promotion of p53. This study provides the essential proof for applying BRG1 to the molecular therapy of RA. PMID:28002318

  10. Exogenous IL-1Ra attenuates intestinal mucositis induced by oxaliplatin and 5-fluorouracil through suppression of p53-dependent apoptosis.

    PubMed

    Wang, Xia; Gao, Jin; Qian, Lan; Gao, Jing; Zhu, Shunying; Wu, Mingyuan; Zhang, Yang; Guan, Wen; Ye, Hao; Yu, Yan; Han, Wei

    2015-01-01

    Chemotherapy-induced intestinal mucositis (CIM) is a major dose-limiting side effect of many chemoagents, resulting in weight loss, diarrhea, and even death. The current treatments for CIM are palliative and have limited benefit. Interleukin-1 receptor antagonist is a natural antagonist of interleukin-1. Our previous studies showed the protective effect of recombinant human interleukin-1 receptor antagonist (rhIL-1Ra) on the intestine in mice after 5-fluorouracil chemotherapy. In this study, we further evaluated rhIL-1Ra in the treatment of CIM induced by different chemoagents and their combination. Normal as well as tumor-bearing mice were administered oxaliplatin (L-OHP), 5-fluorouracil, or their combination to induce intestinal mucositis and mortality. rhIL-1Ra administered after the chemotherapy, but not after the onset of diarrhea, significantly improved mouse survival, attenuated body weight loss, and reduced the incidence, severity, and duration of diarrhea. Histological examination showed that rhIL-1Ra-treated mice had a relatively intact mucosa structure, more proliferating crypt cells, and higher acid mucin content than the vehicle-treated mice. rhIL-1Ra suppressed crypt apoptosis by reducing the levels of proapoptotic proteins in wild-type, but not in IL-1RI or p53 mice. In addition, rhIL-1Ra was as effective as octreotide acetate in the treatment of chemotherapy-induced diarrhea, but with the advantage of reducing the epithelial apoptosis, the major cause of CIM. Importantly, the tumor sensitivity to chemotherapy was not affected by rhIL-1Ra. Thus, our data strongly suggest that rhIL-1Ra may be useful for the treatment of intestinal mucositis and improving the quality of life for cancer patients on chemotherapy.

  11. Cell cycle arrest and apoptosis induced by aspidin PB through the p53/p21 and mitochondria-dependent pathways in human osteosarcoma cells.

    PubMed

    Wan, Daqian; Jiang, Chaoyin; Hua, Xin; Wang, Ting; Chai, Yimin

    2015-10-01

    Aspidin PB is a natural product extracted from Dryopteris fragrans (L.) Schott, which has been characterized for its various biological activities. We reported that aspidin PB induced cell cycle arrest and apoptosis through the p53/p21 and mitochondria-dependent pathways in human osteosarcoma cells. Aspidin PB inhibited the proliferation of Saos-2, U2OS, and HOS cells in a dose-dependent and time-dependent manner. Aspidin PB induced changes in the cell cycle regulators (cyclin A, pRb, CDK2, p53, and p21), which caused cell cycle arrest in the S phase. We also explored the role of siRNA targeted to p53; it led to a dose-dependent attenuation of aspidin PB-induced apoptosis signaling. Moreover, after treatment with aspidin PB, the p21-silenced cells decreased significantly at the S phase. Aspidin PB increased the percentage of cells with mitochondrial membrane potential disruption. Western blot analysis showed that aspidin PB inhibited Bcl-2 expression and induced Bax expression to disintegrate the outer mitochondrial membrane and caused cytochrome C release. Mitochondrial cytochrome C release was associated with the activation of caspase-9 and caspase-3 cascades. Furthermore, the double-stranded DNA breaks and reactive oxygen species signaling were both involved in aspidin PB-induced DNA damage. In addition, aspidin PB inhibited tumor growth significantly in U2OS xenografts. Above all, we conclude that aspidin PB represents a valuable natural source and may potentially be applicable in osteosarcoma therapy.

  12. Epothilones Suppress Neointimal Thickening in the Rat Carotid Balloon-Injury Model by Inducing Vascular Smooth Muscle Cell Apoptosis through p53-Dependent Signaling Pathway

    PubMed Central

    Son, Dong Ju; Jung, Jae Chul; Hong, Jin Tae

    2016-01-01

    Microtubule stabilizing agents (MTSA) are known to inhibit vascular smooth muscle cell (VSMC) proliferation and migration, and effectively reduce neointimal hyperplasia and restenosis. Epothilones (EPOs), non-taxane MTSA, have been found to be effective in the inhibition of VSMC proliferation and neointimal formation by cell cycle arrest. However, effect of EPOs on apoptosis in hyper-proliferated VSMCs as a possible way to reduce neointimal formation and its action mechanism related to VSMC viability has not been suited yet. Thus, the purposes of the present study was to investigate whether EPOs are able to inhibit neointimal formation by inducing apoptosis within the region of neointimal hyperplasia in balloon-injured rat carotid artery, as well as underlying action mechanism. Treatment of EPO-B and EPO-D significantly induced apoptotic cell death and mitotic catastrophe in hyper-proliferated VSMCs, resulting in cell growth inhibition. Further, EPOs significantly suppressed VSMC proliferation and induced apoptosis by activation of p53-dependent apoptotic signaling pathway, Bax/cytochrome c/caspase-3. We further demonstrated that the local treatment of carotid arteries with EPOs potently inhibited neointimal lesion formation by induction of apoptosis in rat carotid injury model. Our findings demonstrate a potent anti-neointimal hyperplasia property of EPOs by inducing p53-depedent apoptosis in hyper-proliferated VSMCs. PMID:27218463

  13. Actvation of NF-kappaB by the API2/MALT1 fusions inhibits p53 dependant but not FAS induced apoptosis: a directional link between NF-kappaB and p53.

    PubMed

    Stoffel, Archontoula; Levine, Arnold J

    2004-08-01

    Interactions between survival pathways and apoptotic cascades play a determinant role in the maintenance of neoplastic clone proliferation and impaired response to apoptosis. Recently, we established a novel interplay between the NF-kappaB survival- and p53 death-pathways in a tumor model system that represents the most common extranodal lymphoid cell neoplasia, MALT (Mucosa Associated Lymphoid Tissue) lymphoma. MALTs are genetically characterized by the t(11;18)(q21;q21) chromosomal translocation that results in API2/MALT1 fusion products. It was shown that distinct API2/MALT1 chimeric proteins function as oncogenes that bilaterally confer a proliferative advantage to the neoplastic clone by activating the NF-kappaB signaling pathway and also inhibiting p53 mediated cell death. Here, we demonstrate that API2/MALT1 mediated inhibition of apoptosis is p53 specific, as distinct API2/MALT1 fusion proteins fail to protect cells from FAS induced cell death. Furthermore, we demonstrate that API2/MALT1 mediated NF-kappaB activation does not alter p53 protein levels or subcellular localization suggesting a post-translational or indirect mechanism of p53 deregulation.

  14. Over-expression of C/EBP-{alpha} induces apoptosis in cultured rat hepatic stellate cells depending on p53 and peroxisome proliferator-activated receptor-{gamma}

    SciTech Connect

    Wang Xueqing; Huang Guangcun; Mei Shuang; Qian Jin; Ji Juling; Zhang Jinsheng

    2009-03-06

    Hepatic stellate cells (HSCs) play a key role in the pathogenesis of hepatic fibrosis. In our previous studies, CCAAT enhancer binding protein-{alpha} (C/EBP-{alpha}) has been shown to be involved in the activation of HSCs and to have a repression effect on hepatic fibrosis in vivo. However, the mechanisms are largely unknown. In this study, we show that the infection of adenovirus vector expressing C/EBP-{alpha} gene (Ad-C/EBP-{alpha}) could induce HSCs apoptosis in a dose- and time-dependent manner by Annexin V/PI staining, caspase-3 activation assay, and flow cytometry. Also, over-expression of C/EBP-{alpha} resulted in the up-regulation of peroxisome proliferator-activated receptor-{gamma} (PPAR-{gamma}) and P53, while P53 expression was regulated by PPAR-{gamma}. In addition, Fas, FasL, DR4, DR5, and TRAIL were studied. The results indicated that the death receptor pathway was mainly involved and regulated by PPAR-{gamma} and p53 in the process of apoptosis triggered by C/EBP-{alpha} in HSCs.

  15. Over-expression of C/EBP-alpha induces apoptosis in cultured rat hepatic stellate cells depending on p53 and peroxisome proliferator-activated receptor-gamma.

    PubMed

    Wang, Xueqing; Huang, Guangcun; Mei, Shuang; Qian, Jin; Ji, Juling; Zhang, Jinsheng

    2009-03-06

    Hepatic stellate cells (HSCs) play a key role in the pathogenesis of hepatic fibrosis. In our previous studies, CCAAT enhancer binding protein-alpha (C/EBP-alpha) has been shown to be involved in the activation of HSCs and to have a repression effect on hepatic fibrosis in vivo. However, the mechanisms are largely unknown. In this study, we show that the infection of adenovirus vector expressing C/EBP-alpha gene (Ad-C/EBP-alpha) could induce HSCs apoptosis in a dose- and time-dependent manner by Annexin V/PI staining, caspase-3 activation assay, and flow cytometry. Also, over-expression of C/EBP-alpha resulted in the up-regulation of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and P53, while P53 expression was regulated by PPAR-gamma. In addition, Fas, FasL, DR4, DR5, and TRAIL were studied. The results indicated that the death receptor pathway was mainly involved and regulated by PPAR-gamma and p53 in the process of apoptosis triggered by C/EBP-alpha in HSCs.

  16. Mdm2 inhibitor Nutlin-3a induces p53-mediated apoptosis by transcription-dependent and transcription-independent mechanisms and may overcome Atm-mediated resistance to fludarabine in chronic lymphocytic leukemia.

    PubMed

    Kojima, Kensuke; Konopleva, Marina; McQueen, Teresa; O'Brien, Susan; Plunkett, William; Andreeff, Michael

    2006-08-01

    Although TP53 mutations are rare in B-cell chronic lymphocytic leukemia (CLL), Mdm2 overexpression has been reported as an alternative cause of p53 dysfunction. We investigated the potential therapeutic use of nongenotoxic p53 activation by a small-molecule antagonist of Mdm2, Nutlin-3a, in CLL. Nutlin-3a induced significant apoptosis in 30 (91%) of 33 samples from previously untreated patients with CLL; all resistant samples had TP53 mutations. Low levels of Atm (ataxia telangiectasia mutated) or high levels of Mdm2 (murine double minute 2) did not prevent Nutlin-3a from inducing apoptosis. Nutlin-3a used transcription-dependent and transcription-independent pathways to induce p53-mediated apoptosis. Predominant activation of the transcription-independent pathway induced more pronounced apoptosis than that of the transcription-dependent pathway, suggesting that activation of the transcription-independent pathway is sufficient to initiate p53-mediated apoptosis in CLL. Combination treatment of Nutlin-3a and fludarabine synergistically increased p53 levels, and induced conformational change of Bax and apoptosis in wild-type p53 cells but not in cells with mutant p53. The synergistic apoptotic effect was maintained in samples with low Atm that were fludarabine resistant. Results suggest that the nongenotoxic activation of p53 by targeting the Mdm2-p53 interaction provides a novel therapeutic strategy for CLL.

  17. DNA double helix unwinding triggers transcription block-dependent apoptosis: a semiquantitative probe of the response of ATM, RNAPII, and p53 to two DNA intercalators.

    PubMed

    Zhang, Zhichao; Wang, Yuanyuan; Song, Ting; Gao, Jin; Wu, Guiye; Zhang, Jing; Qian, Xuhong

    2009-03-16

    We have previously shown the binding modes of two DNA interacting analogues (1)a {3-(4-methyl-piperazin)-8-oxo-8H-acenaphtho[1,2-b]pyrrole-9-carbonitrile} and (3)a {3-(3-dimethylamino-propylamino)-8-oxo-8H-acenaphtho[1,2-b]pyrrole-9-carbonitrile} with the DNA double helix. In this study, we have determined the notably different DNA damage signal pathway elicited by (1)a and (3)a due to the different extents to which they unwind the DNA double helix. First, we have identified that ataxia-telangiectasia-mutated (ATM) protein kinase can respond to DNA double helix unwinding caused by both (1)a and (3)a. In addition, the amount of ATM activation is consistent with the degree to which the DNA double helix was unwound. Consequently, we used (1)a and (3)a to semiquantitatively probe the response of RNA polymerase II (RNAPII) and p53 toward DNA double helix unwinding in vivo. By means of flow cytometry, immunocytochemistry, ChIP, quantitative real-time polymerase chain reaction, and Western blot analyses, we measured the level of p53 and RNAPII phosphorylation, in addition to the dynamics of the RNAPII distribution along the c-Myc gene. These results provided novel evidence for the impact of subtle DNA structural changes on the activity of RNAPII and p53. Moreover, DNA double helix conformational damage-dependent apoptosis was studied for the first time. These results indicated that (1)a can induce transcriptional blockage following a shift of the unphosphorylated IIa form of RNAPII to the phosphorylated IIo form, while (3)a is unable to induce the same effect. Subsequently, p53 accumulation and phosphorylation events occur that lead to apoptosis in the case of (1)a exposure. This suggests that the transcriptional blockage is also correlated to the degree of double helix unwinding. Furthermore, we found that the degree of DNA conformational damage determines whether or not apoptosis occurs through transcriptional blockage. Under our experimental conditions, ATM does not

  18. Cr(VI) induces mitochondrial-mediated and caspase-dependent apoptosis through reactive oxygen species-mediated p53 activation in JB6 Cl41 cells

    SciTech Connect

    Son, Young-Ok; Hitron, J. Andrew; Wang Xin; Chang Qingshan; Pan Jingju; Zhang Zhuo; Liu Jiankang; Wang Shuxia; Lee, Jeong-Chae; Shi Xianglin

    2010-06-01

    Cr(VI) compounds are known to cause serious toxic and carcinogenic effects. Cr(VI) exposure can lead to a severe damage to the skin, but the mechanisms involved in the Cr(VI)-mediated toxicity in the skin are unclear. The present study examined whether Cr(VI) induces cell death by apoptosis or necrosis using mouse skin epidermal cell line, JB6 Cl41 cells. We also investigated the cellular mechanisms of Cr(VI)-induced cell death. This study showed that Cr(VI) induced apoptotic cell death in a dose-dependent manner, as demonstrated by the appearance of cell shrinkage, the migration of cells into the sub-G1 phase, the increase of Annexin V positively stained cells, and the formation of nuclear DNA ladders. Cr(VI) treatment resulted in the increases of mitochondrial membrane depolarization and caspases activation. Electron spin resonance (ESR) and fluorescence analysis revealed that Cr(VI) increased intracellular levels of reactive oxygen species (ROS) such as hydrogen peroxide and superoxide anion radical in dose-dependent manner. Blockage of p53 by si-RNA transfection suppressed mitochondrial changes of Bcl-2 family composition, mitochondrial membrane depolarization, caspase activation and PARP cleavage, leading to the inhibition of Cr(VI)-induced apoptosis. Further, catalase treatment prevented p53 phosphorylation stimulated by Cr(VI) with the concomitant inhibition of caspase activation. These results suggest that Cr(VI) induced a mitochondrial-mediated and caspase-dependent apoptosis in skin epidermal cells through activation of p53, which are mainly mediated by reactive oxidants generated by the chemical.

  19. Wild-type and mutated presenilins 2 trigger p53-dependent apoptosis and down-regulate presenilin 1 expression in HEK293 human cells and in murine neurons

    PubMed Central

    Alves da Costa, Cristine; Paitel, Erwan; Mattson, Mark P.; Amson, Robert; Telerman, Adam; Ancolio, Karine; Checler, Frédéric

    2002-01-01

    Presenilins 1 and 2 are two homologous proteins that, when mutated, account for most early onset Alzheimer's disease. Several lines of evidence suggest that, among various functions, presenilins could modulate cell apoptotic responses. Here we establish that the overexpression of presenilin 2 (PS2) and its mutated form Asn-141-Ile-PS2 alters the viability of human embryonic kidney (HEK)293 cells as established by combined trypan blue exclusion, sodium 3′-[1-(phenylamino-carbonyl)-3,4-tetrazolium]-bis(4-methoxy-6-nitro)benzene sulfonic acid hydrate assay, and propidium iodide incorporation FACS analyses. The two parent proteins increase the acetyl-DEVD-al-sensitive caspase-3-like activity in both HEK293 cells and Telencephalon specific murine neurons, modulate Bax and bcl-2 expressions, and enhance cytochrome C translocation into the cytosol. We show that overexpression of both wild-type and mutated PS2 increases p53-like immunoreactivity and transcriptional activity. We also establish that wild-type- and mutated PS2-induced caspase activation is reduced by p53 antisense approach and by pifithrin-α, a chemical inhibitor of p53. Furthermore, mouse fibroblasts in which the PS2 gene has been knocked out exhibited strongly reduced p53-transcriptional activity. Finally, we establish that the overexpression of both wild-type and mutated PS2 is accompanied by a drastic reduction of endogenous presenilin 1 (PS1) expression. Interestingly, pifithrin-α diminished endogenous PS2 immunoreactivity, whereas the inhibitor increases PS1 expression. Altogether, our data demonstrate that wild-type and familial Alzheimer's disease-linked PS2 trigger apoptosis and down-regulate PS1 expression through p53-dependent mechanisms. PMID:11904448

  20. p53 modulates the AMPK inhibitor compound C induced apoptosis in human skin cancer cells

    SciTech Connect

    Huang, Shi-Wei; Wu, Chun-Ying; Wang, Yen-Ting; Kao, Jun-Kai; Lin, Chi-Chen; Chang, Chia-Che; Mu, Szu-Wei; Chen, Yu-Yu; Chiu, Husan-Wen; Chang, Chuan-Hsun; Liang, Shu-Mei; Chen, Yi-Ju; Huang, Jau-Ling; Shieh, Jeng-Jer

    2013-02-15

    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 p53 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.

  1. Apoptosis and p53 expression in rat adjuvant arthritis

    PubMed Central

    Tak, Paul P; Klapwijk, Maartje S; Broersen, Sophie FM; van de Geest, Deliana A; Overbeek, Marieke; Firestein, Gary S

    2000-01-01

    obtained by arthroscopy of three patients with longstanding (>5 years) RA. After protein extraction in lysis buffer, equal amounts of protein samples from lysates were pooled and examined by Western bolt analysis using anti-p53 monoclonal antibody D07, which recognizes wild-type and mutant p53 from rodents and humans. For immunohistochemical analysis, six rats were sacrificed on day 23 after immunization and synovial tissue of the right ankle joints was snap frozen and evaluated by immunohistochemistry using anti-p53-pan. The sections were evaluated semi-quantitatively using a 0-4 scale. The kruskal-Wallis test for several group means was used to compare the percentage of TUNEL-positive cells at different time points. Results: The percentages of TUNEL-positive cells were strongly dependent on the stage of the disease. Very few TUNEL-positive cells were detected in normal rats or in the early phases of AA; the number of TUNEL-positive cells was 1% or less of the total cell infiltrate, including neutrophils, from days 0-17 (Table 1). On day 23, however, the percentage of TUNEL-positive cells was significantly increased [15.8±5.1% (mean ± standard error of the mean); P=0.01]. TUNEL-positive cells were observed in the intimal lining layer and synovial sublining of the invasive front, as well as in the articular cartilage (Fig. 1). Subsequently, we examined expression of the tumor suppressor gene p53, because this is a key regulator of apoptosis. Expression of p53 in pooled rat AA joint extracts gradually increased from day 0 (6 arbitrary units) to day 23 (173 arbitrary units), which was markedly higher than p53 levels in RA synovium (32 arbitrary units; Table 1). Overexpression of p53 protein on day 23 was confirmed by immunohistochemistry in a separate experiment in six rats with AA. Overexpression of p53 was observed in the intimal lining layer and synovial sublining in all rats on day 23. In all cases a semiquantitative score of 4 was assigned, indicating that 51% or more

  2. Cardiac deficiency of single cytochrome oxidase assembly factor scox induces p53-dependent apoptosis in a Drosophila cardiomyopathy model.

    PubMed

    Martínez-Morentin, Leticia; Martínez, Lidia; Piloto, Sarah; Yang, Hua; Schon, Eric A; Garesse, Rafael; Bodmer, Rolf; Ocorr, Karen; Cervera, Margarita; Arredondo, Juan J

    2015-07-01

    The heart is a muscle with high energy demands. Hence, most patients with mitochondrial disease produced by defects in the oxidative phosphorylation (OXPHOS) system are susceptible to cardiac involvement. The presentation of mitochondrial cardiomyopathy includes hypertrophic, dilated and left ventricular noncompaction, but the molecular mechanisms involved in cardiac impairment are unknown. One of the most frequent OXPHOS defects in humans frequently associated with cardiomyopathy is cytochrome c oxidase (COX) deficiency caused by mutations in COX assembly factors such as Sco1 and Sco2. To investigate the molecular mechanisms that underlie the cardiomyopathy associated with Sco deficiency, we have heart specifically interfered scox expression, the single Drosophila Sco orthologue. Cardiac-specific knockdown of scox reduces fly lifespan, and it severely compromises heart function and structure, producing dilated cardiomyopathy. Cardiomyocytes with low levels of scox have a significant reduction in COX activity and they undergo a metabolic switch from OXPHOS to glycolysis, mimicking the clinical features found in patients harbouring Sco mutations. The major cardiac defects observed are produced by a significant increase in apoptosis, which is dp53-dependent. Genetic and molecular evidence strongly suggest that dp53 is directly involved in the development of the cardiomyopathy induced by scox deficiency. Remarkably, apoptosis is enhanced in the muscle and liver of Sco2 knock-out mice, clearly suggesting that cell death is a key feature of the COX deficiencies produced by mutations in Sco genes in humans.

  3. Cardiac deficiency of single cytochrome oxidase assembly factor scox induces p53-dependent apoptosis in a Drosophila cardiomyopathy model

    PubMed Central

    Martínez-Morentin, Leticia; Martínez, Lidia; Piloto, Sarah; Yang, Hua; Schon, Eric A.; Garesse, Rafael; Bodmer, Rolf; Ocorr, Karen; Cervera, Margarita; Arredondo, Juan J.

    2015-01-01

    The heart is a muscle with high energy demands. Hence, most patients with mitochondrial disease produced by defects in the oxidative phosphorylation (OXPHOS) system are susceptible to cardiac involvement. The presentation of mitochondrial cardiomyopathy includes hypertrophic, dilated and left ventricular noncompaction, but the molecular mechanisms involved in cardiac impairment are unknown. One of the most frequent OXPHOS defects in humans frequently associated with cardiomyopathy is cytochrome c oxidase (COX) deficiency caused by mutations in COX assembly factors such as Sco1 and Sco2. To investigate the molecular mechanisms that underlie the cardiomyopathy associated with Sco deficiency, we have heart specifically interfered scox expression, the single Drosophila Sco orthologue. Cardiac-specific knockdown of scox reduces fly lifespan, and it severely compromises heart function and structure, producing dilated cardiomyopathy. Cardiomyocytes with low levels of scox have a significant reduction in COX activity and they undergo a metabolic switch from OXPHOS to glycolysis, mimicking the clinical features found in patients harbouring Sco mutations. The major cardiac defects observed are produced by a significant increase in apoptosis, which is dp53-dependent. Genetic and molecular evidence strongly suggest that dp53 is directly involved in the development of the cardiomyopathy induced by scox deficiency. Remarkably, apoptosis is enhanced in the muscle and liver of Sco2 knock-out mice, clearly suggesting that cell death is a key feature of the COX deficiencies produced by mutations in Sco genes in humans. PMID:25792727

  4. Mechanisms of p53-Mediated Apoptosis

    DTIC Science & Technology

    2005-03-01

    exclusion assay and under control of the IGFBP3 promoter and 1 pig of empty pcDNA3 or pcDNA3 vector expressing p53 and various mutants. (A) The BD found that...C. C. Harris, and P. p73-deficient mice have neurological, pheromonal and inflammatory defects Hainaut. 2002. The IARC TP53 database: new online

  5. Mechanisms of p53-Mediated Apoptosis

    DTIC Science & Technology

    2007-03-01

    BD) within residues 364 to 393. AD1 is important for transactivation; this domain contains residues that contact the basal transcriptional machinery...256 IGFBP3, a genomic fragment of the IGFBP3 promoter spanning nucleo - tides (nt) 256 to 72, with 1 being the transcriptional start site, was...BD) bind to the IGFBP3 promoter, but full-length p53 cannot recruit the basal transcriptional machinery due to its association with HDAC activity (Fig

  6. Targeting wild-type and mutant p53 with small molecule CP-31398 blocks the growth of rhabdomyosarcoma by inducing ROS-dependent apoptosis

    PubMed Central

    Xu, Jianmin; Timares, Laura; Heilpern, Clay; Weng, Zhiping; Li, Changzhao; Xu, Hui; Pressey, Joseph G.; Elmets, Craig A.; Kopelovich, Levy; Athar, Mohammad

    2010-01-01

    Rhabdomyosarcoma (RMS) is a common soft-tissue sarcoma of childhood in need of more effective therapeutic options. Expression of p53 in RMS is heterogeneous such that some tumors are wild-type whereas others are p53 mutant. The small molecule CP-31398 modulates both the wild-type and mutant p53 proteins. Here we show that CP-31398 blocks the growth of RMS cells that have either wild-type or mutant p53 status. In wild-type A204 cells, CP-31398 increased p53 expression and its downstream transcriptional targets, p21 and mdm2, enhanced expression of apoptosis-related proteins, and reduced proliferation biomarkers. Flow profiling of CP-31398-treated cells indicated an enhancement in sub-G0 and in G1 populations. CP-31398 inhibited proliferation in a manner associated with co-induction of SOX9 and p21. Apoptosis induced by CP-31398 occurred with translocation of p53 to mitochondria, leading to altered mitochondrial membrane potential, cytochrome c release and ROS release. In vivo, CP-31398 decreased the growth of tumor xenografts comprised of wild-type or mutant p53 tumor cells, increasing tumor-free host survival. Our findings indicate that the ability of CP-31398 to modulate wild-type and mutant p53 results in the inhibition of RMS growth and invasiveness. PMID:20682800

  7. The function of Drosophila p53 isoforms in apoptosis

    PubMed Central

    Zhang, B; Rotelli, M; Dixon, M; Calvi, B R

    2015-01-01

    The p53 protein is a major mediator of the cellular response to genotoxic stress and is a crucial suppressor of tumor formation. In a variety of organisms, p53 and its paralogs, p63 and p73, each encode multiple protein isoforms through alternative splicing, promoters, and translation start sites. The function of these isoforms in development and disease are still being defined. Here, we evaluate the apoptotic potential of multiple isoforms of the single p53 gene in the genetic model Drosophila melanogaster. Most previous studies have focused on the p53A isoform, but it has been recently shown that a larger p53B isoform can induce apoptosis when overexpressed. It has remained unclear, however, whether one or both isoforms are required for the apoptotic response to genotoxic stress. We show that p53B is a much more potent inducer of apoptosis than p53A when overexpressed. Overexpression of two newly identified short isoforms perturbed development and inhibited the apoptotic response to ionizing radiation. Analysis of physiological protein expression indicated that p53A is the most abundant isoform, and that both p53A and p53B can form a complex and co-localize to sub-nuclear compartments. In contrast to the overexpression results, new isoform-specific loss-of-function mutants indicated that it is the shorter p53A isoform, not full-length p53B, that is the primary mediator of pro-apoptotic gene transcription and apoptosis after ionizing radiation. Together, our data show that it is the shorter p53A isoform that mediates the apoptotic response to DNA damage, and further suggest that p53B and shorter isoforms have specialized functions. PMID:25882045

  8. Low Levels of p53 Protein and Chromatin Silencing of p53 Target Genes Repress Apoptosis in Drosophila Endocycling Cells

    PubMed Central

    Zhang, Bingqing; Mehrotra, Sonam; Ng, Wei Lun; Calvi, Brian R.

    2014-01-01

    Apoptotic cell death is an important response to genotoxic stress that prevents oncogenesis. It is known that tissues can differ in their apoptotic response, but molecular mechanisms are little understood. Here, we show that Drosophila polyploid endocycling cells (G/S cycle) repress the apoptotic response to DNA damage through at least two mechanisms. First, the expression of all the Drosophila p53 protein isoforms is strongly repressed at a post-transcriptional step. Second, p53-regulated pro-apoptotic genes are epigenetically silenced in endocycling cells, preventing activation of a paused RNA Pol II by p53-dependent or p53-independent pathways. Over-expression of the p53A isoform did not activate this paused RNA Pol II complex in endocycling cells, but over-expression of the p53B isoform with a longer transactivation domain did, suggesting that dampened p53B protein levels are crucial for apoptotic repression. We also find that the p53A protein isoform is ubiquitinated and degraded by the proteasome in endocycling cells. In mitotic cycling cells, p53A was the only isoform expressed to detectable levels, and its mRNA and protein levels increased after irradiation, but there was no evidence for an increase in protein stability. However, our data suggest that p53A protein stability is regulated in unirradiated cells, which likely ensures that apoptosis does not occur in the absence of stress. Without irradiation, both p53A protein and a paused RNA pol II were pre-bound to the promoters of pro-apoptotic genes, preparing mitotic cycling cells for a rapid apoptotic response to genotoxic stress. Together, our results define molecular mechanisms by which different cells in development modulate their apoptotic response, with broader significance for the survival of normal and cancer polyploid cells in mammals. PMID:25211335

  9. Combined treatment with vitamin C and sulindac synergistically induces p53- and ROS-dependent apoptosis in human colon cancer cells.

    PubMed

    Gong, Eun-Yeung; Shin, Yu Jin; Hwang, Ih-Yeon; Kim, Jeong Hee; Kim, Seung-Mi; Moon, Jai-Hee; Shin, Jae-Sik; Lee, Dae-Hee; Hur, Dae Young; Jin, Dong-Hoon; Hong, Seung-Woo; Lee, Won Keun; Lee, Wang-Jae

    2016-09-06

    Sulindac has anti-neoplastic properties against colorectal cancers; however, its use as a chemopreventive agent has been limited due to toxicity and efficacy concerns. Combinatorial treatment of colorectal cancers has been attempted to maximize anti-cancer efficacy with minimal side effects by administrating NSAIDs in combination with other inhibitory compounds or drugs such as l-ascorbic acid (vitamin C), which is known to exhibit cytotoxicity towards various cancer cells at high concentrations. In this study, we evaluated a combinatorial strategy utilizing sulindac and vitamin C. The death of HCT116 cells upon combination therapy occurred via a p53-mediated mechanism. The combination therapeutic resistance developed in isogenic p53 null HCT116 cells and siRNA-mediated p53 knockdown HCT116 cells, but the exogenous expression of p53 in p53 null isogenic cells resulted in the induction of cell death. In addition, we investigated an increased level of intracellular ROS (reactive oxygen species), which was preceded by p53 activation. The expression level of PUMA (p53-upregulated modulator of apoptosis), but not Bim, was significantly increased in HCT116 cells in response to the combination treatment. Taken together, our results demonstrate that combination therapy with sulindac and vitamin C could be a novel anti-cancer therapeutic strategy for p53 wild type colon cancers. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  10. 1800MHz Microwave Induces p53 and p53-Mediated Caspase-3 Activation Leading to Cell Apoptosis In Vitro

    PubMed Central

    Xing, Fuqiang; Zhan, Qiuqiang; He, Yiduo; Cui, Jiesheng; He, Sailing; Wang, Guanyu

    2016-01-01

    Recent studies have reported that exposure of mammalian cells to microwave radiation may have adverse effects such as induction of cell apoptosis. However, the molecular mechanisms underlying microwave induced mammalian cell apoptosis are not fully understood. Here, we report a novel mechanism: exposure to 1800MHz microwave radiation induces p53-dependent cell apoptosis through cytochrome c-mediated caspase-3 activation pathway. We first measured intensity of microwave radiation from several electronic devices with an irradiation detector. Mouse NIH/3T3 and human U-87 MG cells were then used as receivers of 1800MHz electromagnetic radiation (EMR) at a power density of 1209 mW/m2. Following EMR exposure, cells were analyzed for viability, intracellular reactive oxygen species (ROS) generation, DNA damage, p53 expression, and caspase-3 activity. Our analysis revealed that EMR exposure significantly decreased viability of NIH/3T3 and U-87 MG cells, and increased caspase-3 activity. ROS burst was observed at 6 h and 48 h in NIH/3T3 cells, while at 3 h in U-87 MG cells. Hoechst 33258 staining and in situ TUNEL assay detected that EMR exposure increased DNA damage, which was significantly restrained in the presence of N-acetyl-L-cysteine (NAC, an antioxidant). Moreover, EMR exposure increased the levels of p53 protein and p53 target gene expression, promoted cytochrome c release from mitochondrion, and increased caspase-3 activity. These events were inhibited by pretreatment with NAC, pifithrin-α (a p53 inhibitor) and caspase inhibitor. Collectively, our findings demonstrate, for the first time, that 1800MHz EMR induces apoptosis-related events such as ROS burst and more oxidative DNA damage, which in turn promote p53-dependent caspase-3 activation through release of cytochrome c from mitochondrion. These findings thus provide new insights into physiological mechanisms underlying microwave-induced cell apoptosis. PMID:27689798

  11. 1800MHz Microwave Induces p53 and p53-Mediated Caspase-3 Activation Leading to Cell Apoptosis In Vitro.

    PubMed

    Xing, Fuqiang; Zhan, Qiuqiang; He, Yiduo; Cui, Jiesheng; He, Sailing; Wang, Guanyu

    Recent studies have reported that exposure of mammalian cells to microwave radiation may have adverse effects such as induction of cell apoptosis. However, the molecular mechanisms underlying microwave induced mammalian cell apoptosis are not fully understood. Here, we report a novel mechanism: exposure to 1800MHz microwave radiation induces p53-dependent cell apoptosis through cytochrome c-mediated caspase-3 activation pathway. We first measured intensity of microwave radiation from several electronic devices with an irradiation detector. Mouse NIH/3T3 and human U-87 MG cells were then used as receivers of 1800MHz electromagnetic radiation (EMR) at a power density of 1209 mW/m2. Following EMR exposure, cells were analyzed for viability, intracellular reactive oxygen species (ROS) generation, DNA damage, p53 expression, and caspase-3 activity. Our analysis revealed that EMR exposure significantly decreased viability of NIH/3T3 and U-87 MG cells, and increased caspase-3 activity. ROS burst was observed at 6 h and 48 h in NIH/3T3 cells, while at 3 h in U-87 MG cells. Hoechst 33258 staining and in situ TUNEL assay detected that EMR exposure increased DNA damage, which was significantly restrained in the presence of N-acetyl-L-cysteine (NAC, an antioxidant). Moreover, EMR exposure increased the levels of p53 protein and p53 target gene expression, promoted cytochrome c release from mitochondrion, and increased caspase-3 activity. These events were inhibited by pretreatment with NAC, pifithrin-α (a p53 inhibitor) and caspase inhibitor. Collectively, our findings demonstrate, for the first time, that 1800MHz EMR induces apoptosis-related events such as ROS burst and more oxidative DNA damage, which in turn promote p53-dependent caspase-3 activation through release of cytochrome c from mitochondrion. These findings thus provide new insights into physiological mechanisms underlying microwave-induced cell apoptosis.

  12. Knockdown of hepatoma-derived growth factor-related protein-3 induces apoptosis of H1299 cells via ROS-dependent and p53-independent NF-κB activation.

    PubMed

    Yun, Hong Shik; Baek, Jeong-Hwa; Yim, Ji-Hye; Lee, Su-Jae; Lee, Chang-Woo; Song, Jie-Young; Um, Hong-Duck; Park, Jong Kuk; Park, In-Chul; Hwang, Sang-Gu

    2014-07-11

    We previously identified hepatoma-derived growth factor-related protein-3 (HRP-3) as a radioresistant biomarker in p53 wild-type A549 cells and found that p53-dependent induction of the PUMA pathway was a critical event in regulating the radioresistant phenotype. Here, we found that HRP-3 knockdown regulates the radioresistance of p53-null H1299 cells through a distinctly different molecular mechanism. HRP-3 depletion was sufficient to cause apoptosis of H1299 cells by generating substantial levels of reactive oxygen species (ROS) through inhibition of the Nrf2/HO-1 antioxidant pathway. Subsequent, ROS-dependent and p53-independent NF-κB activation stimulated expression of c-Myc and Noxa proteins, thereby inducing the apoptotic machinery. Our results thus extend the range of targets for the development of new drugs to treat both p53 wild-type or p53-null radioresistant lung cancer cells.

  13. Cisplatin-induced apoptosis in non-small-cell lung cancer cells is dependent on Bax- and Bak-induction pathway and synergistically activated by BH3-mimetic ABT-263 in p53 wild-type and mutant cells.

    PubMed

    Matsumoto, Masaru; Nakajima, Wataru; Seike, Masahiro; Gemma, Akihiko; Tanaka, Nobuyuki

    2016-04-29

    Cisplatin is a highly effective anticancer drug for treatment of various tumors including non-small-cell lung cancer (NSCLC), and is especially useful in cases nonresponsive to molecular-targeted drugs. Accumulating evidence has shown that cisplatin activates the p53-dependent apoptotic pathway, but it also induces apoptosis in p53-mutated cancer cells. Here we demonstrated that DNA-damage inducible proapoptotic BH3 (Bcl-2 homology region 3)-only Bcl-2 family members, Noxa, Puma, Bim and Bid, are not involved in cisplatin-induced apoptosis in human NSCLC cell lines. In contrast, the expression of proapoptotic multidomain Bcl-2-family members, Bak and Bax, was induced by cisplatin in p53-dependent and -independent manners, respectively. Moreover, in wild-type p53-expressing cells, cisplatin mainly used the Bak-dependent apoptotic pathway, but this apoptotic pathway shifted to the Bax-dependent pathway by loss-of-function of p53. Furthermore, both Bak- and Bax-induced apoptosis was enhanced by the antiapoptotic Bcl-2 family member, Bcl-XL knockdown, but not by Mcl-1 knockdown. From this result, we tested the effect of ABT-263 (Navitoclax), the specific inhibitor of Bcl-2 and Bcl-XL, but not Mcl-1, and found that ABT-263 synergistically enhanced cisplatin-induced apoptosis in NSCLC cells in the presence or absence of p53. These results indicate a novel regulatory system in cisplatin-induced NSCLC cell apoptosis, and a candidate efficient combination chemotherapy method against lung cancers.

  14. p53-dependent and p53-independent anticancer activity of a new indole derivative in human osteosarcoma cells

    SciTech Connect

    Cappadone, C.; Stefanelli, C.; Malucelli, E.; Zini, M.; Onofrillo, C.; Locatelli, A.; Rambaldi, M.; Sargenti, A.; Merolle, L.; Farruggia, G.; Graziadio, A.; Montanaro, L.; Iotti, S.

    2015-11-13

    Osteosarcoma (OS) is the most common primary malignant tumor of bone, occurring most frequently in children and adolescents. The mechanism of formation and development of OS have been studied for a long time. Tumor suppressor pathway governed by p53 gene are known to be involved in the pathogenesis of osteosarcoma. Moreover, loss of wild-type p53 activity is thought to be a major predictor of failure to respond to chemotherapy in various human cancers. In previous studies, we described the activity of a new indole derivative, NSC743420, belonging to the tubulin inhibitors family, capable to induce apoptosis and arrest of the cell cycle in the G2/M phase of various cancer cell lines. However, this molecule has never been tested on OS cell line. Here we address the activity of NSC743420 by examine whether differences in the p53 status could influence its effects on cell proliferation and death of OS cells. In particular, we compared the effect of the tested molecule on p53-wild type and p53-silenced U2OS cells, and on SaOS2 cell line, which is null for p53. Our results demonstrated that NSC743420 reduces OS cell proliferation by p53-dependent and p53-independent mechanisms. In particular, the molecule induces proliferative arrest that culminate to apoptosis in SaOS2 p53-null cells, while it brings a cytostatic and differentiating effect in U2OS cells, characterized by the cell cycle arrest in G0/G1 phase and increased alkaline phosphatase activity. - Highlights: • The indole derivative NSC743420 induces antitumor effects on osteosarcoma cells. • p53 status could drive the activity of antitumor agents on osteosarcoma cells. • NSC743420 induces cytostatic and differentiating effects on U2OS cells. • NSC743420 causes apoptosis on p53-null SaOS2 cells.

  15. AS-2, a novel inhibitor of p53-dependent apoptosis, prevents apoptotic mitochondrial dysfunction in a transcription-independent manner and protects mice from a lethal dose of ionizing radiation

    SciTech Connect

    Morita, Akinori; Ariyasu, Shinya; Wang, Bing; Asanuma, Tetsuo; Onoda, Takayoshi; Sawa, Akiko; Tanaka, Kaoru; Takahashi, Ippei; Togami, Shotaro; Nenoi, Mitsuru; Inaba, Toshiya; Aoki, Shin

    2014-08-08

    Highlights: • A bidentate HQ derivative, AS-2, suppresses p53-dependent apoptosis by DNA damage. • AS-2 does not significantly affect nuclear p53 response. • UV-excited blue emission of AS-2 clearly showed its extranuclear localization. • AS-2 prevents mitochondrial dysfunction despite the increase of mitochondrial p53. • AS-2 protects mice from a radiation dose that causes lethal hematopoietic syndrome. - Abstract: In a previous study, we reported that some tetradentate zinc(II) chelators inhibit p53 through the denaturation of its zinc-requiring structure but a chelator, Bispicen, a potent inhibitor of in vitro apoptosis, failed to show any efficient radioprotective effect against irradiated mice because the toxicity of the chelator to mice. The unsuitability of using tetradentate chelators as radioprotectors prompted us to undertake a more extensive search for p53-inhibiting agents that are weaker zinc(II) chelators and therefore less toxic. Here, we show that an 8-hydroxyquinoline (8HQ) derivative, AS-2, suppresses p53-dependent apoptosis through a transcription-independent mechanism. A mechanistic study using cells with different p53 characteristics revealed that the suppressive effect of AS-2 on apoptosis is specifically mediated through p53. In addition, AS-2 was less effective in preventing p53-mediated transcription-dependent events than pifithrin-μ (PFTμ), an inhibitor of transcription-independent apoptosis by p53. Fluorescence visualization of the extranuclear distribution of AS-2 also supports that it is ineffective on the transcription-dependent pathway. Further investigations revealed that AS-2 suppressed mitochondrial apoptotic events, such as the mitochondrial release of intermembrane proteins and the loss of mitochondrial membrane potential, although AS-2 resulted in an increase in the mitochondrial translocation of p53 as opposed to the decrease of cytosolic p53, and did not affect the apoptotic interaction of p53 with Bcl-2. AS-2 also

  16. Activation of p53-dependent responses in tumor cells treated with a PARC-interacting peptide

    SciTech Connect

    Vitali, Roberta; Cesi, Vincenzo; Tanno, Barbara; Ferrari-Amorotti, Giovanna; Dominici, Carlo; Calabretta, Bruno; Raschella, Giuseppe

    2008-04-04

    We tested the activity of a p53 carboxy-terminal peptide containing the PARC-interacting region in cancer cells with wild type cytoplasmic p53. Peptide delivery was achieved by fusing it to the TAT transduction domain (TAT-p53-C-ter peptide). In a two-hybrid assay, the tetramerization domain (TD) of p53 was necessary and sufficient to bind PARC. The TAT-p53-C-ter peptide disrupted the PARC-p53 complex. Peptide treatment caused p53 nuclear relocation, p53-dependent changes in gene expression and enhancement of etoposide-induced apoptosis. These studies suggest that PARC-interacting peptides are promising candidates for the enhancement of p53-dependent apoptosis in tumors with wt cytoplasmic p53.

  17. p53-dependent and -independent mechanisms are involved in (E)-1-(2-hydroxyphenyl)-3-(2-methoxynaphthalen-1-yl)prop-2-en-1-one (HMP)-induced apoptosis in HCT116 colon cancer cells.

    PubMed

    Shin, Soon Young; Ahn, Seunghyun; Koh, Dongsoo; Lim, Yoongho

    2016-10-28

    (E)-1-(2-hydroxyphenyl)-3-(2-methoxynaphthalen-1-yl)prop-2-en-1-one (HMP) is a novel synthetic naphthal chalcone derivative. The aim of this study was to investigate the mode of action underlying the antitumor activity of HMP. We found that treatment with HMP potently inhibited the clonogenicity and triggered cell death in HCT116 colon cancer cells. Flow cytometry showed that HMP induced an increase in the population of sub-G0/G1-phase cells. Annexin V binding assay revealed that HMP triggered apoptotic cell death. Furthermore, HMP stimulated the cleavages of caspase-7 and its substrate poly (ADP-ribose) polymerase (PARP). HMP promoted γ-H2AX formation and the production of reactive oxygen species (ROS), and up-regulated expression of the tumor suppressor p53. Interestingly, HMP-induced caspase-7 processing was not completely abrogated in p53-null (p53(-/-)) HCT116 cells, suggesting that p53-dependent and -independent mechanisms are involved in HMP-induced apoptosis. Egr-1, a zinc finger transcription factor, was upregulated by HMP. Silencing of Egr-1 by shRNA significantly reduced HMP-induced caspase-7 and PARP cleavages, regardless of p53 status. These results suggest that HMP triggers caspase-mediated apoptosis through two distinct mechanisms involving p53-dependent and p53-independent, Egr-1-dependent pathways. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Grape Seed Proanthocyanidins Induce Apoptosis through p53, Bax, and Caspase 3 Pathways1

    PubMed Central

    Roy, Anshu M; Baliga, Manjeshwar S; Elmets, Craig A; Katiyar, Santosh K

    2005-01-01

    Abstract Grape seed proanthocyanidins (GSP) have been shown to inhibit skin chemical carcinogenesis and photocarcinogenesis in mice. The mechanisms responsible for the anticarcinogenic effects of GSP are not clearly understood. Here, we report that treatment of JB6 C141 cells (a well-developed cell culture model for studying tumor promotion in keratinocytes) and p53+/+ fibroblasts with GSP resulted in a dose-dependent induction of apoptosis. GSP-induced (20–80 g/ml) apoptosis was observed by using immunofluorescence (27–90% apoptosis) and flow cytometry (18–87% apoptosis). The induction of apoptosis by GSP was p53-dependent because it occurred mainly in cells expressing wild-type p53 (p53+/+; 15–80%) to a much greater extent than in p53-deficient cells (p53-/-; 6–20%). GSP-induced apoptosis in JB6 C141 cells was associated with increased expression of the tumor-suppressor protein, p53, and its phosphorylation at Ser15. The antiapoptotic proteins, Bcl-2 and Bcl-xl, were downregulated by GSP, whereas the expression of the pro-apoptotic protein, Bax, and the levels of cytochrome c release, Apaf-1, caspase-9, and cleaved caspase 3 (p19 and p17) were markedly increased in JB6 C141 cells. The downregulation of Bcl-2 and upregulation of Bax were also observed in wild-type p53 (p53+/+) fibroblasts but was not observed in their p53-deficient counterparts. These data clearly demonstrate that GSP-induced apoptosis is p53-dependent and mediated through the Bcl-2, Bax, and caspase 3 pathways. PMID:15720815

  19. Cycloheximide suppresses radiation-induced apoptosis in MOLT-4 cells with Arg72 variant of p53 through translational inhibition of p53 accumulation.

    PubMed

    Ito, Azusa; Morita, Akinori; Ohya, Soichiro; Yamamoto, Shinichi; Enomoto, Atsushi; Ikekita, Masahiko

    2011-01-01

    The human T-cell leukemia cell line MOLT-4 is highly radiosensitive, and thus it is often used as a model of p53-dependent radiation-induced apoptosis. Two branches of the p53-mediated apoptotic pathway are reported: "transcription-dependent" and "transcription-independent." However, the relative contribution of each in different types of cells is not yet clearly defined. Moreover, recent studies have shown that the codon 72 polymorphic variants of p53 show different sensitivities to apoptosis signals. The Arg72 variant has a more potent apoptosis-inducing activity in mitochondria than the Pro72 variant. Here, we initially investigated the codon 72 polymorphism of p53 in MOLT-4 cells. Analysis of the p53 exon 4 genomic DNA sequence, which includes codon 72, revealed that MOLT-4 cells are homozygous for the allele encoding Arg72. We next investigated the involvement of the transcription-independent function of p53 using an RNA synthesis inhibitor, actinomycin D (ActD), and a protein synthesis inhibitor, cycloheximide (CHX), and found that the apoptosis was suppressed by CHX but not by ActD. We also revealed that the suppressive effect of CHX on apoptosis was specifically mediated by p53, using a p53-knockdown MOLT-4 transfectant. Furthermore, the suppressive effect of CHX on apoptosis was highly correlated with the suppression of p53 protein accumulation, and less correlated with the suppression of p53 target genes expression. These results indicated that p53 transactivation is not necessary to induce apoptosis, and that p53 protein accumulation itself is both necessary and sufficient to do so.

  20. P53 mediates amosite asbestos-induced alveolar epithelial cell mitochondria-regulated apoptosis.

    PubMed

    Panduri, Vijayalakshmi; Surapureddi, Sailesh; Soberanes, Saul; Weitzman, Sigmund A; Chandel, Navdeep; Kamp, David W

    2006-04-01

    Asbestos causes pulmonary toxicity in part by generating reactive oxygen species that cause DNA damage. We previously showed that the mitochondria-regulated (intrinsic) death pathway mediates alveolar epithelial cell (AEC) DNA damage and apoptosis. Because p53 regulates the DNA damage response in part by inducing intrinsic cell death, we determined whether p53-dependent transcriptional activity mediates asbestos-induced AEC mitochondrial dysfunction and apoptosis. We show that inhibitors of p53-dependent transcriptional activation (pifithrin and type 16-E6 protein) block asbestos-induced AEC mitochondrial membrane potential change (DeltaPsim), caspase 9 activation, and apoptosis. We demonstrate that asbestos activates p53 promoter activity, mRNA levels, protein expression, and Bax and p53 mitochondrial translocation. Further, pifithrin, E6, phytic acid, or rho(0)-A549 cells (cells incapable of mitochondrial reactive oxygen species production) block asbestos-induced p53 activation. Finally, we show that asbestos augments p53 expression in cells at the bronchoalveolar duct junctions of rat lungs and that phytic acid prevents this. These data suggest that p53-dependent transcription pathways mediate asbestos-induced AEC mitochondria-regulated apoptosis. This suggests an important interactive effect between p53 and the mitochondria in the pathogenesis of asbestos-induced pulmonary toxicity that may have broader implications for our understanding of pulmonary fibrosis and lung cancer.

  1. ARF and ATM/ATR cooperate in p53-mediated apoptosis upon oncogenic stress

    SciTech Connect

    Pauklin, Siim . E-mail: spauklin@ut.ee; Kristjuhan, Arnold; Maimets, Toivo; Jaks, Viljar

    2005-08-26

    Induction of apoptosis is pivotal for eliminating cells with damaged DNA or deregulated proliferation. We show that tumor suppressor ARF and ATM/ATR kinase pathways cooperate in the induction of apoptosis in response to elevated expression of c-myc, {beta}-catenin or human papilloma virus E7 oncogenes. Overexpression of oncogenes leads to the formation of phosphorylated H2AX foci, induction of Rad51 protein levels and ATM/ATR-dependent phosphorylation of p53. Inhibition of ATM/ATR kinases abolishes both induction of Rad51 and phosphorylation of p53, and remarkably reduces the level of apoptosis induced by co-expression of oncogenes and ARF. However, the induction of apoptosis is downregulated in p53-/- cells and does not depend on activities of ATM/ATR kinases, indicating that efficient induction of apoptosis by oncogene activation depends on coordinated action of ARF and ATM/ATR pathways in the regulation of p53.

  2. Wip1 inhibitor GSK2830371 inhibits neuroblastoma growth by inducing Chk2/p53-mediated apoptosis

    PubMed Central

    Chen, Zhenghu; Wang, Long; Yao, Dayong; Yang, Tianshu; Cao, Wen-Ming; Dou, Jun; Pang, Jonathan C.; Guan, Shan; Zhang, Huiyuan; Yu, Yang; Zhao, Yanling; Wang, Yongfeng; Xu, Xin; Shi, Yan; Patel, Roma; Zhang, Hong; Vasudevan, Sanjeev A.; Liu, Shangfeng; Yang, Jianhua; Nuchtern, Jed G.

    2016-01-01

    Neuroblastoma (NB) is the most common extracranial tumor in children. Unlike in most adult tumors, tumor suppressor protein 53 (p53) mutations occur with a relatively low frequency in NB and the downstream function of p53 is intact in NB cell lines. Wip1 is a negative regulator of p53 and hindrance of Wip1 activity by novel inhibitor GSK2830371 is a potential strategy to activate p53’s tumor suppressing function in NB. Yet, the in vivo efficacy and the possible mechanisms of GSK2830371 in NB have not yet been elucidated. Here we report that novel Wip1 inhibitor GSK2830371 induced Chk2/p53-mediated apoptosis in NB cells in a p53-dependent manner. In addition, GSK2830371 suppressed the colony-formation potential of p53 wild-type NB cell lines. Furthermore, GSK2830371 enhanced doxorubicin- (Dox) and etoposide- (VP-16) induced cytotoxicity in a subset of NB cell lines, including the chemoresistant LA-N-6 cell line. More importantly, GSK2830371 significantly inhibited tumor growth in an orthotopic xenograft NB mouse model by inducing Chk2/p53-mediated apoptosis in vivo. Taken together, this study suggests that GSK2830371 induces Chk2/p53-mediated apoptosis both in vitro and in vivo in a p53 dependent manner. PMID:27991505

  3. Neem oil limonoids induces p53-independent apoptosis and autophagy

    PubMed Central

    Chandra, Dhyan

    2012-01-01

    Azadirachta indica, commonly known as neem, has a wide range of medicinal properties. Neem extracts and its purified products have been examined for induction of apoptosis in multiple cancer cell types; however, its underlying mechanisms remain undefined. We show that neem oil (i.e., neem), which contains majority of neem limonoids including azadirachtin, induced apoptotic and autophagic cell death. Gene silencing demonstrated that caspase cascade was initiated by the activation of caspase-9, whereas caspase-8 was also activated late during neem-induced apoptosis. Pretreatment of cancer cells with pan caspase inhibitor, z-VAD inhibited activities of both initiator caspases (e.g., caspase-8 and -9) and executioner caspase-3. Neem induced the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria, suggesting the involvement of both caspase-dependent and AIF-mediated apoptosis. p21 deficiency caused an increase in caspase activities at lower doses of neem, whereas p53 deficiency did not modulate neem-induced caspase activation. Additionally, neem treatment resulted in the accumulation of LC3-II in cancer cells, suggesting the involvement of autophagy in neem-induced cancer cell death. Low doses of autophagy inhibitors (i.e., 3-methyladenine and LY294002) did not prevent accumulation of neem-induced LC3-II in cancer cells. Silencing of ATG5 or Beclin-1 further enhanced neem-induced cell death. Phosphoinositide 3-kinase (PI3K) or autophagy inhibitors increased neem-induced caspase-3 activation and inhibition of caspases enhanced neem-induced autophagy. Together, for the first time, we demonstrate that neem induces caspase-dependent and AIF-mediated apoptosis, and autophagy in cancer cells. PMID:22915764

  4. Neem oil limonoids induces p53-independent apoptosis and autophagy.

    PubMed

    Srivastava, Pragya; Yadav, Neelu; Lella, Ravi; Schneider, Andrea; Jones, Anthony; Marlowe, Timothy; Lovett, Gabrielle; O'Loughlin, Kieran; Minderman, Hans; Gogada, Raghu; Chandra, Dhyan

    2012-11-01

    Azadirachta indica, commonly known as neem, has a wide range of medicinal properties. Neem extracts and its purified products have been examined for induction of apoptosis in multiple cancer cell types; however, its underlying mechanisms remain undefined. We show that neem oil (i.e., neem), which contains majority of neem limonoids including azadirachtin, induced apoptotic and autophagic cell death. Gene silencing demonstrated that caspase cascade was initiated by the activation of caspase-9, whereas caspase-8 was also activated late during neem-induced apoptosis. Pretreatment of cancer cells with pan caspase inhibitor, z-VAD inhibited activities of both initiator caspases (e.g., caspase-8 and -9) and executioner caspase-3. Neem induced the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria, suggesting the involvement of both caspase-dependent and AIF-mediated apoptosis. p21 deficiency caused an increase in caspase activities at lower doses of neem, whereas p53 deficiency did not modulate neem-induced caspase activation. Additionally, neem treatment resulted in the accumulation of LC3-II in cancer cells, suggesting the involvement of autophagy in neem-induced cancer cell death. Low doses of autophagy inhibitors (i.e., 3-methyladenine and LY294002) did not prevent accumulation of neem-induced LC3-II in cancer cells. Silencing of ATG5 or Beclin-1 further enhanced neem-induced cell death. Phosphoinositide 3-kinase (PI3K) or autophagy inhibitors increased neem-induced caspase-3 activation and inhibition of caspases enhanced neem-induced autophagy. Together, for the first time, we demonstrate that neem induces caspase-dependent and AIF-mediated apoptosis, and autophagy in cancer cells.

  5. Knockdown of hepatoma-derived growth factor-related protein-3 induces apoptosis of H1299 cells via ROS-dependent and p53-independent NF-κB activation

    SciTech Connect

    Yun, Hong Shik; Baek, Jeong-Hwa; Yim, Ji-Hye; Lee, Su-Jae; Lee, Chang-Woo; Song, Jie-Young; Um, Hong-Duck; Park, Jong Kuk; Park, In-Chul; Hwang, Sang-Gu

    2014-07-11

    Highlights: • HRP-3 is a radiation- and anticancer drug-responsive protein in H1299 cells. • Depletion of HRP-3 induces apoptosis of radio- and chemoresistant H1299 cells. • Depletion of HRP-3 promotes ROS generation via inhibition of the Nrf2/HO-1 pathway. • ROS generation enhances NF-κB activity, which acts as an upstream signal in the c-Myc/Noxa apoptotic pathway. - Abstract: We previously identified hepatoma-derived growth factor-related protein-3 (HRP-3) as a radioresistant biomarker in p53 wild-type A549 cells and found that p53-dependent induction of the PUMA pathway was a critical event in regulating the radioresistant phenotype. Here, we found that HRP-3 knockdown regulates the radioresistance of p53-null H1299 cells through a distinctly different molecular mechanism. HRP-3 depletion was sufficient to cause apoptosis of H1299 cells by generating substantial levels of reactive oxygen species (ROS) through inhibition of the Nrf2/HO-1 antioxidant pathway. Subsequent, ROS-dependent and p53-independent NF-κB activation stimulated expression of c-Myc and Noxa proteins, thereby inducing the apoptotic machinery. Our results thus extend the range of targets for the development of new drugs to treat both p53 wild-type or p53-null radioresistant lung cancer cells.

  6. p53-dependent delayed effects of radiation vary according to time of irradiation of p53 + / - mice.

    PubMed

    Okazaki, Ryuji; Ootsuyama, Akira

    2014-01-01

    We previously reported that in p53 (+ / -) mice that had been given a whole-body dose of 3 Gy at 8 weeks of age, p53-dependent delayed effects of radiation, as manifested in T-cell receptor (TCR) variant fractions (VF) instability in mouse splenocytes, were biphasic, namely, induction of TCR-VF mutation reappeared at 44 weeks. The manifestation of the delayed effects and the measures of biological markers varied according to the timing of irradiation. We also reported that the decrease in function of the p53 gene was related to the effects of a delayed mutation. In the present study, we investigated the functions and mutations of the p53 gene in old age for p53 (+ / -) mice following irradiation at various ages. p53 (+ / -) mice were given a whole-body dose of 3 Gy at 8, 28 or 40 weeks of age. There were significant differences for all variables tested at 8 weeks of age. This was similarly the case for mice irradiated at 28 weeks of age, in which there were also significant differences in TCR VF and the percentage of apoptosis. In mice irradiated at 40 weeks of age, there were significant differences for all considered variables except for the p53 allele. We demonstrated that the different patterns of delayed mutation of the p53 gene at 56 weeks of age depended on the age at which mice had undergone 3-Gy whole-body irradiation. Our conclusions are limited to variation in p53-dependent delayed effects according to the time of irradiation.

  7. Andrographolide enhances 5-fluorouracil-induced apoptosis via caspase-8-dependent mitochondrial pathway involving p53 participation in hepatocellular carcinoma (SMMC-7721) cells.

    PubMed

    Yang, Lu; Wu, Dingfang; Luo, Kewang; Wu, Shihua; Wu, Ping

    2009-04-18

    Despite recent significant advances in the treatment of human carcinoma (HCC), the results of chemotherapy to date remain unsatisfactory. 5-Fluorouracil (5-FU) still represents the cornerstone of treatment of carcinoma, and resistance to the actions of 5-FU is a major obstacle to successful chemotherapy. More effective treatment strategies may involve combinations of agents with activity against HCC. Andrographolide (ANDRO), a natural bicyclic diterpenoid lactone isolated from Andrographis paniculata, has been shown to suppress the growth of HCC cells and trigger apoptosis in vitro. To assess the suitability of ANDRO as a chemotherapeutic agent in HCC, its cytotoxic effects have been evaluated both as a single agent and in combination with 5-FU. ANDRO potentiates the cytotoxic effect of 5-FU in HCC cell line SMMC-7721 through apoptosis. ANDRO alone induces SMMC-7721 apoptosis with p53 expression, Bax conformation and caspase-3,8,9 activation. Surprisingly, the addition of ANDRO to 5-FU induces synergistic apoptosis, which could be corroborated to the increased caspase-8, p53 activity and the significant changes of Bax conformation in these cells, resulting in increased losses of mitochondrial membrane potential, increased release of cytochrome c, and activation of caspase-9 and caspase-3. Suppression of caspase-8 with the specific inhibitor z-IETD-fmk abrogates largely ANDRO/5-FU biological activity by preventing mitochondrial membrane potential disappearance, caspase-3,9 activation and subsequent apoptosis. The results suggest that ANDRO may be effective in combination with 5-FU for the treatment of HCC cells SMMC-7721.

  8. Activation of p38-MAPK by CXCL4/CXCR3 axis contributes to p53-dependent intestinal apoptosis initiated by 5-fluorouracil.

    PubMed

    Gao, Jing; Gao, Jin; Qian, Lan; Wang, Xia; Wu, Mingyuan; Zhang, Yang; Ye, Hao; Zhu, Shunying; Yu, Yan; Han, Wei

    2014-08-01

    Chemotherapy-induced mucositis (CIM) is a major does limiting side-effect of chemoagents such as 5-fluorouracil (5-FU). Molecules involved in this disease process are still not fully understood. We proposed that the homeostatically regulated genes during CIM may participate in the disease. A cluster of such genes were previously identified by expression gene-array from the mouse jejunum in 5-FU-induced mucositis model. Here, we report that CXCL4 is such a homeostatically regulated gene and serves as a new target for the antibody treatment of CIM. CXCL4 and its receptor CXCR3 were confirmed at both the gene and protein levels to be homeostatically regulated during 5-FU-induced mucositis. Using of CXCL4 neutralizing monoclonal antibody (CXCL4mab) decreased the incidence, severity, and duration of the chemotherapy-induced diarrhea, the major symptom of CIM, in a 5-FU mouse CIM model. Mechanistically, CXCL4mab reduced the apoptosis of the crypt epithelia by suppression of the 5-FU-induced expression of p53 and Bax through its receptor CXCR3. The downstream signaling pathway of CXCL4 in activation of the epithelial apoptosis was identified in an intestinal epithelial cell line (IEC-6). CXCL4 activated the phosphorylation of p38 MAPK, which mediated the stimulated expression of p53 and Bax, and resulted in the ultimate activation of Caspase-8, -9, and -3. Taken together, activation of CXCL4 expression by 5-FU in mice participates in 5-FU-induced intestinal mucositis through upregulation of p53 via activation of p38-MAPK, and CXCL4mab is potentially beneficial in preventing CIM in the intestinal tract.

  9. Inhibitory effect of oleanolic acid on hepatocellular carcinoma via ERK-p53-mediated cell cycle arrest and mitochondrial-dependent apoptosis.

    PubMed

    Wang, Xin; Bai, Hua; Zhang, Xiaodi; Liu, Jiangzheng; Cao, Peipei; Liao, Nai; Zhang, Wei; Wang, Zhao; Hai, Chunxu

    2013-06-01

    Incidence of hepatocellular carcinoma (HCC) is dramatically increasing and is the third cause of cancer death worldwide. One key approach to control HCC is chemoprevention by naturally occurring agents. This study aims at investigating the antitumor effect of oleanolic acid (OA) and the molecular mechanisms. BALB/c mice were injected subcutaneously with HepG2 cells to establish transplanted tumors. Apoptosis and cell cycle arrest-related markers and signaling cascades were determined by western blot, immunofluorescence, reverse transcriptase-polymerase chain reaction and flow cytometric analysis. OA exhibited inhibitory effect on HCC through induction of apoptosis and cell cycle arrest both in transplanted tumors and in HepG2 cells. OA induced apoptosis through mitochondrial pathway, evidenced by inhibition of Akt/mammalian target of rapamycin pathway, mitochondrial dysfunction, transient increase of adenosine triphosphate, increase of Bax/Bcl-2 ratio, increased release of cytochrome c and activation of caspase/poly (ADP-ribose) polymerase. Activation of mitochondrial apoptotic pathway may be due to reactive oxygen species generated by mitochondrial fatty acid oxidation, resulted from enhancement of lipolysis regulated by cyclic adenosine 3',5'-monophosphate response element-binding protein-hormone-sensitive lipase/peroxisome proliferator-activated receptor γ signaling. OA induced G2/M cell cycle arrest through p21-mediated downregulation of cyclin B1/cdc2. Cyclooxygenase-2 (COX-2) and p53 were involved in OA-exerted effect, and extracellular signal-regulated kinase-p53 signaling played a central role in OA-activated cascades responsible for apoptosis and cell cycle arrest. OA demonstrated significant antitumor activities in HCC in vivo and in vitro models. These data provide new insights into the mechanisms underlying the antitumor effect of OA.

  10. LACE1 interacts with p53 and mediates its mitochondrial translocation and apoptosis

    PubMed Central

    Cesnekova, Jana; Spacilova, Jana; Hansikova, Hana; Houstek, Josef; Zeman, Jiri; Stiburek, Lukas

    2016-01-01

    p53 is a major cellular tumor suppressor that in addition to its nuclear, transcription-dependent activity is also known to function extranuclearly. Cellular stressors such as reactive oxygen species can promote translocation of p53 into mitochondria where it acts to protect mitochondrial genome or trigger cell death via transcription-independent manner. Here we report that the mammalian homologue of yeast mitochondrial Afg1 ATPase (LACE1) promotes translocation of p53 into mitochondria. We further show that LACE1 exhibits significant pro-apoptotic activity, which is dependent on p53, and that the protein is required for normal mitochondrial respiratory function. LACE1 physically interacts with p53 and is necessary for mitomycin c-induced translocation of p53 into mitochondria. Conversely, increased expression of LACE1 partitions p53 to mitochondria, causes reduction in nuclear p53 content and induces apoptosis. Thus, LACE1 mediates mitochondrial translocation of p53 and its transcription-independent apoptosis. PMID:27323408

  11. Trichodermin induces c-Jun N-terminal kinase-dependent apoptosis caused by mitotic arrest and DNA damage in human p53-mutated pancreatic cancer cells and xenografts.

    PubMed

    Chien, Ming-Hsien; Lee, Tzong-Huei; Lee, Wei-Jiunn; Yeh, Yen-Hsiu; Li, Tsai-Kun; Wang, Po-Chuan; Chen, Jih-Jung; Chow, Jyh-Ming; Lin, Yung-Wei; Hsiao, Michael; Wang, Shih-Wei; Hua, Kuo-Tai

    2017-03-01

    Pancreatic cancer is an aggressive malignancy, which generally responds poorly to chemotherapy. In this study, trichodermin, an endophytic fungal metabolite from Nalanthamala psidii, was identified as a potent and selective antitumor agent in human pancreatic cancer. Trichodermin exhibited antiproliferative effects against pancreatic cancer cells, especially p53-mutated cells (MIA PaCa-2 and BxPC-3) rather than normal pancreatic epithelial cells. We found that trichodermin induced caspase-dependent and mitochondrial intrinsic apoptosis. Trichodermin also increased apoptosis through mitotic arrest by activating Cdc2/cyclin B1 complex activity. Moreover, trichodermin promoted the activation of c-Jun N-terminal kinase (JNK), and inhibition of JNK by its inhibitor, shRNA, or siRNA significantly reversed trichodermin-mediated caspase-dependent apoptosis. Trichodermin triggered DNA damage stress to activate p53 function for executing apoptosis in p53-mutated cells. Importantly, we demonstrated that trichodermin with efficacy similar to gemcitabine, profoundly suppressed tumor growth through inducing intratumoral DNA damage and JNK activation in orthotopic pancreatic cancer model. Based on these findings, trichodermin is a potential therapeutic agent worthy of further development into a clinical trial candidate for treating cancer, especially the mutant p53 pancreatic cancer.

  12. Pin1-Induced Proline Isomerization in Cytosolic p53 Mediates BAX Activation and Apoptosis.

    PubMed

    Follis, Ariele Viacava; Llambi, Fabien; Merritt, Parker; Chipuk, Jerry E; Green, Douglas R; Kriwacki, Richard W

    2015-08-20

    The cytosolic fraction of the tumor suppressor p53 activates the apoptotic effector protein BAX to trigger apoptosis. Here we report that p53 activates BAX through a mechanism different from that associated with activation by BH3 only proteins (BIM and BID). We observed that cis-trans isomerization of proline 47 (Pro47) within p53, an inherently rare molecular event, was required for BAX activation. The prolyl isomerase Pin1 enhanced p53-dependent BAX activation by catalyzing cis-trans interconversion of p53 Pro47. Our results reveal a signaling mechanism whereby proline cis-trans isomerization in one protein triggers conformational and functional changes in a downstream signaling partner. Activation of BAX through the concerted action of cytosolic p53 and Pin1 may integrate cell stress signals to induce a direct apoptotic response. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Gene expression profiling analysis reveals arsenic-induced cell cycle arrest and apoptosis in p53-proficient and p53-deficient cells through differential gene pathways

    SciTech Connect

    Yu Xiaozhong Robinson, Joshua F.; Gribble, Elizabeth; Hong, Sung Woo; Sidhu, Jaspreet S.; Faustman, Elaine M.

    2008-12-15

    Arsenic (As) is a well-known environmental toxicant and carcinogen as well as an effective chemotherapeutic agent. The underlying mechanism of this dual capability, however, is not fully understood. Tumor suppressor gene p53, a pivotal cell cycle checkpoint signaling protein, has been hypothesized to play a possible role in mediating As-induced toxicity and therapeutic efficiency. In this study, we found that arsenite (As{sup 3+}) induced apoptosis and cell cycle arrest in a dose-dependent manner in both p53{sup +/+} and p53{sup -/-} mouse embryonic fibroblasts (MEFs). There was, however, a distinction between genotypes in the apoptotic response, with a more prominent induction of caspase-3 in the p53{sup -/-} cells than in the p53{sup +/+} cells. To examine this difference further, a systems-based genomic analysis was conducted comparing the critical molecular mechanisms between the p53 genotypes in response to As{sup 3+}. A significant alteration in the Nrf2-mediated oxidative stress response pathway was found in both genotypes. In p53{sup +/+} MEFs, As{sup 3+} induced p53-dependent gene expression alterations in DNA damage and cell cycle regulation genes. However, in the p53{sup -/-} MEFs, As{sup 3+} induced a significant up-regulation of pro-apoptotic genes (Noxa) and down-regulation of genes in immune modulation. Our findings demonstrate that As-induced cell death occurs through a p53-independent pathway in p53 deficient cells while apoptosis induction occurs through p53-dependent pathway in normal tissue. This difference in the mechanism of apoptotic responses between the genotypes provides important information regarding the apparent dichotomy of arsenic's dual mechanisms, and potentially leads to further advancement of its utility as a chemotherapeutic agent.

  14. Resistance of differentiating spermatogonia to radiation-induced apoptosis and loss in p53-deficient mice.

    PubMed

    Hasegawa, M; Zhang, Y; Niibe, H; Terry, N H; Meistrich, M L

    1998-03-01

    The effect of the p53 gene on the survival of mouse testicular cells was evaluated by analysis of degenerating and terminal transferase-mediated end labeling (TUNEL)-positive cells and the subsequent production of further differentiated progeny. In p53 null mice, in contrast to wild-type mice, radiation induced negligible levels of degenerating or TUNEL-positive differentiating spermatogonia within 24 h. This was correlated with higher production of differentiated progeny of the differentiating spermatogonia in p53 null mice. Contrary to the differentiating spermatogonia, the stem spermatogonia of p53 null mice produced fewer differentiated progeny after irradiation than did the stem cells of wild-type mice. We conclude that, because the degeneration and TUNEL positivity of the differentiating spermatogonia in mice of different genotypes were correlated with each other and were dependent on p53, this process is indeed apoptosis. In the differentiating spermatogonia, p53-dependent apoptosis accounted for the bulk of the loss of their progeny after irradiation. Furthermore, whereas the differentiating spermatogonia died by apoptosis that was dependent on p53, the stem spermatogonia, which are more radioresistant, did not.

  15. A Single Mutant, A276S of p53 Turns the Switch to Apoptosis

    PubMed Central

    Reaz, Shams; Mossalam, Mohanad; Okal, Abood; Lim, Carol. S.

    2013-01-01

    The tumor suppressor protein p53 induces apoptosis, cell cycle arrest, and DNA repair along with other functions in a transcription-dependent manner1. The selection of these functions depends on sequence-specific recognition of p53 to a target decameric sequence of gene promoters2. Amino acid residues in p53 that directly bind to DNA were analyzed, and the replacement of A276 in p53 with selected amino acids elucidated its importance in promoter transcription. For most apoptotic and cell cycle gene promoters, position 9 of the target decameric sequence is a cytosine while for DNA repair gene promoters, thymine is found instead. Therefore, selective binding to the cytosine at the 9th position may transcribe apoptotic gene promoters and thus can induce apoptosis and cell cycle arrest. Molecular modeling with PyMOL indicated that substitution of a hydrophilic residue, A276S, would prefer binding to cytosine at the 9th position of the target decameric sequence whereas substitution of a hydrophobic residue (A276F) would fail to do so. Correspondingly, A276S demonstrated higher transcription of PUMA, PERP, and p21WAF1/CIP1gene promoters containing a cytosine at the 9th position and lower transcription of GADD45 gene promoter containing a thymine at the 9th position compared to wild-type p53. Cell cycle analysis showed that A276S maintained similar G1/G0 phase arrest as wild-type p53. Additionally, A276S induced higher apoptosis than wild-type p53 as measured by DNA segmentation and 7-AAD assay. Since the status of endogenous p53 can influence the activity of the exogenous p53, we examined the activity of A276S in HeLa cells (wild-type endogenous p53) in addition to T47D cells (mutated and mislocalized endogenous p53). The same apoptotic trend in both cell lines suggested A276S can induce cell death regardless of endogenous p53 status. Cell proliferation assay depicted that A276S efficiently reduced the viability of T47D cells more than wild-type p53 over time. We

  16. Nanosecond pulsed electric fields induce apoptosis in p53-wildtype and p53-null HCT116 colon carcinoma cells.

    PubMed

    Hall, Emily H; Schoenbach, Karl H; Beebe, Stephen J

    2007-09-01

    Non-ionizing radiation produced by nanosecond pulsed electric fields (nsPEFs) is an alternative to ionizing radiation for cancer treatment. NsPEFs are high power, low energy (non-thermal) pulses that, unlike plasma membrane electroporation, modulate intracellular structures and functions. To determine functions for p53 in nsPEF-induced apoptosis, HCT116p53(+/+) and HCT116p53(-/-) colon carcinoma cells were exposed to multiple pulses of 60 kV/cm with either 60 ns or 300 ns durations and analyzed for apoptotic markers. Several apoptosis markers were observed including cell shrinkage and increased percentages of cells positive for cytochrome c, active caspases, fragmented DNA, and Bax, but not Bcl-2. Unlike nsPEF-induced apoptosis in Jurkat cells (Beebe et al. 2003a) active caspases were observed before increases in cytochrome c, which occurred in the presence and absence of Bax. Cell shrinkage occurred only in cells with increased levels of Bax or cytochrome c. NsPEFs induced apoptosis equally in HCT116p53(+/+) and HCT116p53(-/-) cells. These results demonstrate that non-ionizing radiation produced by nsPEFs can act as a non-ligand agonist with therapeutic potential to induce apoptosis utilizing mitochondrial-independent mechanisms in HCT116 cells that lead to caspase activation and cell death in the presence or absence of p-53 and Bax.

  17. Genotoxic stress-induced expression of p53 and apoptosis in leukemic clam hemocytes with cytoplasmically sequestered p53.

    PubMed

    Böttger, Stefanie; Jerszyk, Emily; Low, Ben; Walker, Charles

    2008-02-01

    In nature, the soft shell clam, Mya arenaria, develops a fatal blood cancer in which a highly conserved homologue for wild-type human p53 protein is rendered nonfunctional by cytoplasmic sequestration. In untreated leukemic clam hemocytes, p53 is complexed throughout the cytoplasm with overexpressed variants for both clam homologues (full-length variant, 1,200-fold and truncated variant, 620-fold above normal clam hemocytes) of human mortalin, an Hsp70 family protein. In vitro treatment with etoposide only and in vivo treatment with either etoposide or mitoxantrone induces DNA damage, elevates expression (600-fold) and promotes nuclear translocation of p53, and results in apoptosis of leukemic clam hemocytes. Pretreatment with wheat germ agglutinin followed by etoposide treatment induces DNA damage and elevates p53 expression (893-fold) but does not overcome cytoplasmic sequestration of p53 or induce apoptosis. We show that leukemic clam hemocytes have an intact p53 pathway, and that maintenance of this tumor phenotype requires nuclear absence of p53, resulting from its localization in the cytoplasm of leukemic clam hemocytes. The effects of these topoisomerase II poisons may result as mortalin-based cytoplasmic tethering is overwhelmed by de novo expression of p53 protein after DNA damage induced by genotoxic stress. Soft shell clam leukemia provides excellent in vivo and in vitro models for developing genotoxic and nongenotoxic cancer therapies for reactivating p53 transcription in human and other animal cancers displaying mortalin-based cytoplasmic sequestration of the p53 tumor suppressor, such as colorectal cancers and primary and secondary glioblastomas, though not apparently leukemias or lymphomas.

  18. Drosophila p53 isoforms differentially regulate apoptosis and apoptosis-induced proliferation.

    PubMed

    Dichtel-Danjoy, M-L; Ma, D; Dourlen, P; Chatelain, G; Napoletano, F; Robin, M; Corbet, M; Levet, C; Hafsi, H; Hainaut, P; Ryoo, H D; Bourdon, J-C; Mollereau, B

    2013-01-01

    Irradiated or injured cells enter apoptosis, and in turn, promote proliferation of surrounding unaffected cells. In Drosophila, apoptotic cells have an active role in proliferation, where the caspase Dronc and p53 induce mitogen expression and growth in the surrounding tissues. The Drosophila p53 gene structure is conserved and encodes at least two protein isoforms: a full-length isoform (Dp53) and an N-terminally truncated isoform (DΔNp53). Historically, DΔNp53 was the first p53 isoform identified and was thought to be responsible for all p53 biological activities. It was shown that DΔNp53 induces apoptosis by inducing the expression of IAP antagonists, such as Reaper. Here we investigated the roles of Dp53 and DΔNp53 in apoptosis and apoptosis-induced proliferation. We found that both isoforms were capable of activating apoptosis, but that they each induced distinct IAP antagonists. Expression of DΔNp53 induced Wingless (Wg) expression and enhanced proliferation in both 'undead cells' and in 'genuine' apoptotic cells. In contrast to DΔNp53, Dp53 did not induce Wg expression in the absence of the endogenous p53 gene. Thus, we propose that DΔNp53 is the main isoform that regulates apoptosis-induced proliferation. Understanding the roles of Drosophila p53 isoforms in apoptosis and in apoptosis-induced proliferation may shed new light on the roles of p53 isoforms in humans, with important implications in cancer biology.

  19. Inhibition of protein kinase CK2 with the clinical-grade small ATP-competitive compound CX-4945 or by RNA interference unveils its role in acute myeloid leukemia cell survival, p53-dependent apoptosis and daunorubicin-induced cytotoxicity.

    PubMed

    Quotti Tubi, Laura; Gurrieri, Carmela; Brancalion, Alessandra; Bonaldi, Laura; Bertorelle, Roberta; Manni, Sabrina; Pavan, Laura; Lessi, Federica; Zambello, Renato; Trentin, Livio; Adami, Fausto; Ruzzene, Maria; Pinna, Lorenzo A; Semenzato, Gianpietro; Piazza, Francesco

    2013-10-12

    The involvement of protein kinase CK2 in sustaining cancer cell survival could have implications also in the resistance to conventional and unconventional therapies. Moreover, CK2 role in blood tumors is rapidly emerging and this kinase has been recognized as a potential therapeutic target. Phase I clinical trials with the oral small ATP-competitive CK2 inhibitor CX-4945 are currently ongoing in solid tumors and multiple myeloma. We have analyzed the expression of CK2 in acute myeloid leukemia and its function in cell growth and in the response to the chemotherapeutic agent daunorubicin We employed acute myeloid leukemia cell lines and primary blasts from patients grouped according to the European LeukemiaNet risk classification. Cell survival, apoptosis and sensitivity to daunorubicin were assessed by different means. p53-dependent CK2-inhibition-induced apoptosis was investigated in p53 wild-type and mutant cells. CK2a was found highly expressed in the majority of samples across the different acute myeloid leukemia prognostic subgroups as compared to normal CD34+ hematopoietic and bone marrow cells. Inhibition of CK2 with CX-4945, K27 or siRNAs caused a p53-dependent acute myeloid leukemia cell apoptosis. CK2 inhibition was associated with a synergistic increase of the cytotoxic effects of daunorubicin. Baseline and daunorubicin-induced STAT3 activation was hampered upon CK2 blockade. These results suggest that CK2 is over expressed across the different acute myeloid leukemia subsets and acts as an important regulator of acute myeloid leukemia cell survival. CK2 negative regulation of the protein levels of tumor suppressor p53 and activation of the STAT3 anti-apoptotic pathway might antagonize apoptosis and could be involved in acute myeloid leukemia cell resistance to daunorubicin.

  20. DIMP53-1: A novel small-molecule dual inhibitor of p53-MDM2/X interactions with multifunctional p53-dependent anticancer properties.

    PubMed

    Soares, Joana; Espadinha, Margarida; Raimundo, Liliana; Ramos, Helena; Gomes, Ana Sara; Gomes, Sara; Loureiro, Joana B; Inga, Alberto; Reis, Flávio; Gomes, Célia; Santos, Maria M M; Saraiva, Lucília

    2017-03-10

    The transcription factor p53 plays a crucial role in cancer development and dissemination, and thus p53-targeted therapies are amongst the most encouraging anticancer strategies. In human cancers with wild-type (wt) p53, its inactivation by interaction with murine double minute (MDM)2 and MDMX is a common event. Simultaneous inhibition of the p53 interaction with both MDMs is crucial to restore the tumor suppressor activity of p53. Here we describe the synthesis of the new tryptophanol-derived oxazoloisoindolinone DIMP53-1 and identify its activity as a dual inhibitor of the p53-MDM2/X interactions using a yeast-based assay. DIMP53-1 caused growth inhibition, mediated by p53 stabilization and upregulation of p53 transcriptional targets involved in cell cycle arrest and apoptosis, in wt p53-expressing tumor cells, including MDM2- or MDMX-overexpressing cells. Importantly, DIMP53-1 abolishes the p53-MDM2/X interactions by binding to p53, in human colon adenocarcinoma HCT116 cells. DIMP53-1 also inhibited the migration and invasion of HCT116 cells, and the migration and tube formation of HMVEC-D endothelial cells. Notably, in human tumor xenograft mice models, DIMP53-1 showed a p53-dependent antitumor activity through induction of apoptosis and inhibition of proliferation and angiogenesis. Finally, no genotoxicity or undesirable toxic effects were observed with DIMP53-1. In conclusion, DIMP53-1 is a novel p53 activator, which potentially binds to p53 inhibiting its interaction with MDM2 and MDMX. Although target-directed, DIMP53-1 has a multifunctional activity, targeting major hallmarks of cancer through its anti-proliferative, pro-apoptotic, anti-angiogenic, anti-invasive and anti-migratory properties. DIMP53-1 is a promising anticancer drug candidate and an encouraging starting point to develop improved derivatives for clinical application.

  1. Undecylprodigiosin selectively induces apoptosis in human breast carcinoma cells independent of p53

    SciTech Connect

    Ho, T.-F.; Ma, C.-J.; Lu, C.-H.; Tsai, Yo-Ting; Wei, Y.-H.; Chang, J.-S.; Lai, J.-K.; Cheuh, Pin-Ju; Yeh, C.-T.; Tang, P.-C.; Jingua, T.C.; Ko, J.-L.; Liu, F.-S.; Yen, H.E.

    2007-12-15

    Undecylprodigiosin (UP) is a bacterial bioactive metabolite produced by Streptomyces and Serratia. In this study, we explored the anticancer effect of UP. Human breast carcinoma cell lines BT-20, MCF-7, MDA-MB-231 and T47D and one nonmalignant human breast epithelial cell line, MCF-10A, were tested in this study. We found that UP exerted a potent cytotoxicity against all breast carcinoma cell lines in a dose- and time-dependent manner. In contrast, UP showed limited toxicity to MCF-10A cells, indicating UP's cytotoxic effect is selective for malignant cells. UP's cytotoxic effect was due to apoptosis, as confirmed by positive TUNEL signals, annexin V-binding, caspase 9 activation and PARP cleavage. Notably, UP-induced apoptosis was blocked by the pan-caspase inhibitor z-VAD.fmk, further indicating the involvement of caspase activity. Moreover, UP caused a marked decrease of the levels of antiapoptotic BCL-X{sub L}, Survivin and XIAP while enhancing the levels of proapoptotic BIK, BIM, MCL-1S and NOXA, consequently favoring induction of apoptosis. Additionally, we found that cells with functional p53 (MCF-7, T47D) or mutant p53 (BT-20, MDA-MB-231) were both susceptible to UP's cytotoxicity. Importantly, UP was able to induce apoptosis in MCF-7 cells with p53 knockdown by RNA interference, confirming the dispensability of p53 in UP-induced apoptosis. Overall, our results establish that UP induces p53-independent apoptosis in breast carcinoma cells with no marked toxicity to nonmalignant cells, raising the possibility of its use as a new chemotherapeutic drug for breast cancer irrespective of p53 status.

  2. Methylsulfonylmethane Induces p53 Independent Apoptosis in HCT-116 Colon Cancer Cells

    PubMed Central

    Karabay, Arzu Zeynep; Koc, Asli; Ozkan, Tulin; Hekmatshoar, Yalda; Sunguroglu, Asuman; Aktan, Fugen; Buyukbingol, Zeliha

    2016-01-01

    Methylsulfonylmethane (MSM) is an organic sulfur-containing compound which has been used as a dietary supplement for osteoarthritis. MSM has been shown to reduce oxidative stress and inflammation, as well as exhibit apoptotic or anti-apoptotic effects depending on the cell type or activating stimuli. However, there are still a lot of unknowns about the mechanisms of actions of MSM. In this study, MSM was tested on colon cancer cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay and flow cytometric analysis revealed that MSM inhibited cell viability and increased apoptotic markers in both HCT-116 p53 +/+ and HCT-116 p53 −/− colon cancer cells. Increased poly (ADP-ribose) polymerase (PARP) fragmentation and caspase-3 activity by MSM also supported these findings. MSM also modulated the expression of various apoptosis-related genes and proteins. Moreover, MSM was found to increase c-Jun N-terminal kinases (JNK) phosphorylation in both cell lines, dose-dependently. In conclusion, our results show for the first time that MSM induces apoptosis in HCT-116 colon cancer cells regardless of their p53 status. Since p53 is defective in >50% of tumors, the ability of MSM to induce apoptosis independently of p53 may offer an advantage in anti-tumor therapy. Moreover, the remarkable effect of MSM on Bim, an apoptotic protein, also suggests its potential use as a novel chemotherapeutic agent for Bim-targeted anti-cancer therapies. PMID:27428957

  3. Suppression of the p300-dependent mdm2 negative-feedback loop induces the p53 apoptotic function

    PubMed Central

    Thomas, Anju; White, Eileen

    1998-01-01

    The p53 tumor suppressor gene product interacts with the p300 transcriptional coactivator that regulates the transactivation of p53-inducible genes. The adenovirus E1A protein has been shown to bind to p300 and inhibit its function. E1A inhibits p53 transactivation and also promotes p53 accumulation by a p300-dependent mechanism. Murine double minute 2 (Mdm2) is a transcriptional target of p53 that binds to p53 and inhibits its transcriptional activity. E1A inhibited mdm2 transactivation without affecting the expression of p21WAF1 or Bax, which resulted in high levels of p53 accumulation and apoptosis. Ectopic expression of p300 restored Mdm2 levels and inhibited p53-dependent apoptosis, as did ectopic expression of Mdm2. Thus, p300 is required for mdm2 induction by p53 and the subsequent inhibition of p53 stabilization. Inhibition of p300 by E1A results in stabilization of p53 and causes apoptosis. Moreover, E1B 19K or Bcl-2 expression in E1A-transformed cells abrogated p53-dependent apoptosis by restoring mdm2 transactivation by p53. Hence, p300 regulation of mdm2 expression controls apoptotic activity of p53, and 19K or Bcl-2 bypass E1A inhibition of p300 transactivation of Mdm2. PMID:9649502

  4. p53 Suppresses E2F1-dependent PLK1 expression upon DNA damage by forming p53-E2F1-DNA complex.

    PubMed

    Zhou, Zhe; Cao, Ji-Xiang; Li, Shu-Yan; An, Guo-Shun; Ni, Ju-Hua; Jia, Hong-Ti

    2013-12-10

    E2F1 is implicated in transcriptional activation of polo-like kinase-1 (PLK1), but yet the mechanism is not fully understood. PLK1 suppression plays an important checkpoint role in response to DNA damage. Suppression of the PLK1 gene by binding of p53 to upstream p53RE2 element in the promoter has been recently revealed. Here we report another mechanism, in which p53 interacts with E2F1 to form p53-E2F1-DNA complex repressing E2F1-dependent PLK1 expression. PLK1 was downregulated in cisplatin exposed HCT116p53(+/+) but not HCT116p53(-/-) cells, indicating p53-suppressed PLK1 upon DNA damage. Co-transfection and reporter enzyme assays revealed that p53 suppressed but E2F1 promoted PLK1 gene activation. 5'-Deletion and substitution mutations showed multiple positive cis-elements residing in the PLK1 promoter, of which at least two E2F1 sites at positions -75/-68 and -40/-32 were required for the full activity of the promoter. Combination of 5'-deletion and substitution mutations with over-expression of p53 showed that suppression of the PLK1 gene by p53 was E2F1-dependent: mutation of the E2F1 site at position -75/-68 partially abrogated suppression activity of p53; mutation of E2F1 site at position -40/-32 released from p53 suppression of PLK1 gene completely. Co-immunoprecipitation and electrophoretic mobility shift assay showed that DNA damage promoted p53-E2F1 interaction, thereby creating a p53-E2F1 complex assembly on the PLK1 promoter in vitro. The in vivo formation of p53-E2F1-PLK1 promoter complex upon DNA damage was further evidenced by chromatin immunoprecipitation (ChIP) and re-ChIP. In addition, we showed that suppression of PLK1 by p53 promoted apoptosis. Our data suggest that p53 may interact with E2F1 to form p53-E2F1-DNA complex suppressing E2F1-dependent PLK1 expression. The model of p53 action on E2F1-activated PLK1 gene may explain at least partly how p53 as a suppressor regulates the downstream effects of E2F1 in cellular stresses including DNA

  5. p53 and p21 determine the sensitivity of noscapine-induced apoptosis in colon cancer cells.

    PubMed

    Aneja, Ritu; Ghaleb, Amr M; Zhou, Jun; Yang, Vincent W; Joshi, Harish C

    2007-04-15

    We have previously discovered the naturally occurring antitussive alkaloid noscapine as a tubulin-binding agent that attenuates microtubule dynamics and arrests mammalian cells at mitosis via activation of the c-Jun NH(2)-terminal kinase pathway. It is well established that the p53 protein plays a crucial role in the control of tumor cell response to chemotherapeutic agents and DNA-damaging agents; however, the relationship between p53-driven genes and drug sensitivity remains controversial. In this study, we compared chemosensitivity, cell cycle distribution, and apoptosis on noscapine treatment in four cell lines derived from the colorectal carcinoma HCT116 cells: p53(+/+) (p53-wt), p53(-/-) (p53-null), p21(-/-) (p21-null), and BAX(-/-) (BAX-null). Using these isogenic variants, we investigated the roles of p53, BAX, and p21 in the cellular response to treatment with noscapine. Our results show that noscapine treatment increases the expression of p53 over time in cells with wild-type p53 status. This increase in p53 is associated with an increased apoptotic BAX/Bcl-2 ratio consistent with increased sensitivity of these cells to apoptotic stimuli. Conversely, loss of p53 and p21 alleles had a counter effect on both BAX and Bcl-2 expression and the p53-null and p21-null cells were significantly resistant to the antiproliferative and apoptotic effects of noscapine. All but the p53-null cells displayed p53 protein accumulation in a time-dependent manner on noscapine treatment. Interestingly, despite increased levels of p53, p21-null cells were resistant to apoptosis, suggesting a proapoptotic role of p21 and implying that p53 is a necessary but not sufficient condition for noscapine-mediated apoptosis.

  6. Relationship of p53 Mutations to Epidermal Cell Proliferation and Apoptosis in Human UV-Induced Skin Carcinogenesis1

    PubMed Central

    Einspahr, Janine G; Alberts, David S; Warneke, James A; Bozzo, Paul; Basye, Jenny; Grogan, Thomas M; Nelson, Mark A; Bowden, G Tim

    1999-01-01

    Abstract Human skin is continually subjected to UV-irradiation with the p53 gene playing a pivotal role in repair of UV-induced DNA damage and apoptosis. Consequently, p53 alterations are early events in human UV-induced skin carcinogenesis. We studied 13 squamous cell carcinomas (SCC), 16 actinic keratoses (AK), 13 samples adjacent to an AK (chronically sun-damaged), and 14 normal-appearing skin samples for p53 mutation, p53 immunostaining (IHC), apoptosis (in situ TUNEL and morphology), and proliferation (PCNA). The frequency of p53 mutation increased from 14% in normal skin, to 38.5% in sun-damaged skin, 63% in AK, and 54% in SCC. p53 IHC increased similarly. Apoptosis (TUNEL) increased from 0.06 ± 0.02%, to 0.1 ± 0.2, 0.3 ± 0.3, and 0.4 ± 0.3 in normal skin, sun-damaged skin, AK, and SCC, respectively. Apoptosis was strongly correlated with proliferation (i.e., TUNEL and PCNA, r = 0.7, P < 0.0001), and proliferation was significantly increased in the progression from normal skin to SCC. Bax was significantly increased in SCC compared to AK. These data imply that apoptosis in samples with a high frequency of p53 mutation may not necessarily be p53-dependent. We suggest that there is a mechanism for apoptosis in response to increased cellular proliferation that is p53-independent. PMID:10933063

  7. Induction of apoptosis by bleomycin in p53-null HL-60 leukemia cells.

    PubMed

    Gimonet, Delphine; Landais, Emilie; Bobichon, Helene; Coninx, Paul; Liautaud-Roger, Françoise

    2004-02-01

    The role of p53 in apoptosis and the contrasting p53 status in tumors prompted us to investigate the bleomycin-induced apoptosis in p53-null human leukemia HL-60 cells (bleomycin at 160 microM for 7.5 h). Cells with apoptotic phenotype increased from 0.87% in controls to 9.40% in bleomycin-treated cells. Both the enzymes, caspase-3 and -8, were activated. Furthermore, the apoptotic phenotypes totally disappeared with zVAD-fmk, a caspase inhibitor. Besides, cytochrome c release from mitochondria happened simultaneously to apoptotic phenotypes, shrinkage of mitochondria but being independent of the mitochondrial permeability transition, since cyclosporine A and bongkrekic acid were inefficient on induced apoptosis. On the other hand, incubations with bleomycin (BLM) did not result in detectable changes in the expression of Bcl-2- and Bax-mRNA neither Bcl-2- or Bax-proteins. In conclusion, we suggest that BLM can produce apoptosis independently of p53 through three mechanisms: i) at the nuclear level by its endonuclease activities; ii) at the cell membrane, by activating caspases; and iii) at the mitochondria by releasing cytochrome c. These results indicate that BLM-induced apoptosis in HL-60 cells results from the activation of a mitochondria-dependent caspase cascade which includes also the activation of the initiator caspase-8.

  8. Mouse peroxiredoxin V is a thioredoxin peroxidase that inhibits p53-induced apoptosis.

    PubMed

    Zhou, Y; Kok, K H; Chun, A C; Wong, C M; Wu, H W; Lin, M C; Fung, P C; Kung, H; Jin, D Y

    2000-02-24

    We have identified human and mouse peroxiredoxin V (Prx-V) by virtue of the sequence homologies to yeast peroxisomal antioxidant enzyme PMP20. Prx-V represents the fifth of the six currently known subfamilies of mammalian peroxiredoxins. It is a novel organellar enzyme that has orthologs in bacteria. Biochemically, Prx-V is a thioredoxin peroxidase. One important aspect of p53 function in mammalian cells involves induction of apoptosis likely mediated by redox. We show that overexpression of Prx-V prevented the p53-dependent generation of reactive oxygen species. Likewise, Prx-V inhibited p53-induced apoptosis. Thus, Prx-V is critically involved in intracellular redox signaling. Copyright 2000 Academic Press.

  9. p53 is required for metformin-induced growth inhibition, senescence and apoptosis in breast cancer cells.

    PubMed

    Li, Puyu; Zhao, Ming; Parris, Amanda B; Feng, Xiaoshan; Yang, Xiaohe

    2015-09-04

    The p53 tumor repressor gene is commonly mutated in human cancers. The tumor inhibitory effect of metformin on p53-mutated breast cancer cells remains unclear. Data from the present study demonstrated that p53 knockdown or mutation has a negative effect on metformin or phenformin-induced growth inhibition, senescence and apoptosis in breast cancer cells. We also found that p53 reactivating agent nutlin-3α and CP/31398 promoted metformin-induced growth inhibition, senescence and apoptosis in MCF-7 (wt p53) and MDA-MB-231 (mt p53) cells, respectively. Treatment of MCF-7 cells with metformin or phenformin induced increase in p53 protein levels and the transcription of its downstream target genes, Bax and p21, in a dose-dependent manner. Moreover, we demonstrated that AMPK-mTOR signaling played a role in metformin-induced p53 up-regulation. The present study showed that p53 is required for metformin or phenformin-induced growth inhibition, senescence and apoptosis in breast cancer cells. The combination of metformin with p53 reactivating agents, like nutlin-3α and CP/31398, is a promising strategy for improving metformin-mediated anti-cancer therapy, especially for tumors with p53 mutations. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Impact of the p53 status of tumor cells on extrinsic and intrinsic apoptosis signaling

    PubMed Central

    2013-01-01

    Background The p53 protein is the best studied target in human cancer. For decades, p53 has been believed to act mainly as a tumor suppressor and by transcriptional regulation. Only recently, the complex and diverse function of p53 has attracted more attention. Using several molecular approaches, we studied the impact of different p53 variants on extrinsic and intrinsic apoptosis signaling. Results We reproduced the previously published results within intrinsic apoptosis induction: while wild-type p53 promoted cell death, different p53 mutations reduced apoptosis sensitivity. The prediction of the impact of the p53 status on the extrinsic cell death induction was much more complex. The presence of p53 in tumor cell lines and primary xenograft tumor cells resulted in either augmented, unchanged or reduced cell death. The substitution of wild-type p53 by mutant p53 did not affect the extrinsic apoptosis inducing capacity. Conclusions In summary, we have identified a non-expected impact of p53 on extrinsic cell death induction. We suggest that the impact of the p53 status of tumor cells on extrinsic apoptosis signaling should be studied in detail especially in the context of therapeutic approaches that aim to restore p53 function to facilitate cell death via the extrinsic apoptosis pathway. PMID:23594441

  11. S-benzyl-cysteine-mediated cell cycle arrest and apoptosis involving activation of mitochondrial-dependent caspase cascade through the p53 pathway in human gastric cancer SGC-7901 cells.

    PubMed

    Sun, Hua-Jun; Meng, Lin-Yi; Shen, Yang; Zhu, Yi-Zhun; Liu, Hong-Rui

    2013-01-01

    S-benzyl-cysteine (SBC) is a structural analog of S-allylcysteine (SAC), which is one of the major water- soluble compounds in aged garlic extract. In this study, anticancer activities and the underlying mechanisms of SBC action were investigated and compared these with those of SAC using human gastric cancer SGC-7901 cells. SBC significantly suppressed the survival rate of SGC-7901 cells in a concentration- and time-dependent manner, and the inhibitory activities of SBC were stronger than those of SAC. Flow cytometry revealed that SBC induced G2-phase arrest and apoptosis in SGC-7901 cells. Typical apoptotic morphological changes were observed by Hoechst 33258 dye assay. SBC-treatment dramatically induced the dissipation of mitochondrial membrane potential (Δψm), and enhanced the enzymatic activities of caspase-9 and caspase-3 whilst hardly affecting caspase-8 activity. Furthermore, Western blotting indicated that SBC-induced apoptosis was accompanied by up-regulation of the expression of p53, Bax and the down-regulation of Bcl-2. Taken together, this study suggested that SBC exerts cytotoxic activity involving activation of mitochondrial-dependent apoptosis through p53 and Bax/Bcl-2 pathways in human gastric cancer SGC-7901 cells.

  12. Drosophila p53 isoforms differentially regulate apoptosis and apoptosis-induced proliferation

    PubMed Central

    Dichtel-Danjoy, M-L; Ma, D; Dourlen, P; Chatelain, G; Napoletano, F; Robin, M; Corbet, M; Levet, C; Hafsi, H; Hainaut, P; Ryoo, H D; Bourdon, J-C; Mollereau, B

    2013-01-01

    Irradiated or injured cells enter apoptosis, and in turn, promote proliferation of surrounding unaffected cells. In Drosophila, apoptotic cells have an active role in proliferation, where the caspase Dronc and p53 induce mitogen expression and growth in the surrounding tissues. The Drosophila p53 gene structure is conserved and encodes at least two protein isoforms: a full-length isoform (Dp53) and an N-terminally truncated isoform (DΔNp53). Historically, DΔNp53 was the first p53 isoform identified and was thought to be responsible for all p53 biological activities. It was shown that DΔNp53 induces apoptosis by inducing the expression of IAP antagonists, such as Reaper. Here we investigated the roles of Dp53 and DΔNp53 in apoptosis and apoptosis-induced proliferation. We found that both isoforms were capable of activating apoptosis, but that they each induced distinct IAP antagonists. Expression of DΔNp53 induced Wingless (Wg) expression and enhanced proliferation in both ‘undead cells' and in ‘genuine' apoptotic cells. In contrast to DΔNp53, Dp53 did not induce Wg expression in the absence of the endogenous p53 gene. Thus, we propose that DΔNp53 is the main isoform that regulates apoptosis-induced proliferation. Understanding the roles of Drosophila p53 isoforms in apoptosis and in apoptosis-induced proliferation may shed new light on the roles of p53 isoforms in humans, with important implications in cancer biology. PMID:22898807

  13. Depletion of the Adaptor Protein NCK Increases UV-Induced p53 Phosphorylation and Promotes Apoptosis

    PubMed Central

    Errington, Timothy M.; Macara, Ian G.

    2013-01-01

    The cellular response to DNA damage requires the coordination of many proteins involved in diverse molecular processes. Discrete molecular pathways are becoming increasingly well understood, but the interconnectivity and coordination of multiple pathways remains less clear. We now show that NCK, an adapter protein involved in cytoskeletal responses to tyrosine kinase receptor signaling, accumulates in the nucleus in response to DNA damage and this translocation can be blocked by specific inhibition of the ATR protein kinase. Strikingly, HeLa cells depleted of NCK undergo apoptosis shortly after UV irradiation, as monitored by caspase-3 cleavage and PARP cleavage. This rapid, hyperactive apoptosis in NCK depleted cells might be p53 dependent, because loss of NCK also increased UV-induced p53 phosphorylation. Importantly, depletion of SOCS7, which is necessary for NCK nuclear translocation, phenocopies NCK depletion, indicating the nuclear accumulation of NCK is responsible for these molecular events. There are two NCK isoforms that have mostly redundant functions, and although NCK2 appears to have a greater contribution, depletion of NCK1 or NCK2, led to increased p53 phosphorylation and early apoptosis after UV exposure. These data reveal a novel function for NCK in regulating p53 phosphorylation and apoptosis, and provide evidence for interconnectedness of growth factor signaling proteins and the DNA damage response. PMID:24086708

  14. DNA strand breaks: the DNA template alterations that trigger p53-dependent DNA damage response pathways.

    PubMed Central

    Nelson, W G; Kastan, M B

    1994-01-01

    The tumor suppressor protein p53 serves as a critical regulator of a G1 cell cycle checkpoint and of apoptosis following exposure of cells to DNA-damaging agents. The mechanism by which DNA-damaging agents elevate p53 protein levels to trigger G1/S arrest or cell death remains to be elucidated. In fact, whether damage to the DNA template itself participates in transducing the signal leading to p53 induction has not yet been demonstrated. We exposed human cell lines containing wild-type p53 alleles to several different DNA-damaging agents and found that agents which rapidly induce DNA strand breaks, such as ionizing radiation, bleomycin, and DNA topoisomerase-targeted drugs, rapidly triggered p53 protein elevations. In addition, we determined that camptothecin-stimulated trapping of topoisomerase I-DNA complexes was not sufficient to elevate p53 protein levels; rather, replication-associated DNA strand breaks were required. Furthermore, treatment of cells with the antimetabolite N(phosphonoacetyl)-L-aspartate (PALA) did not cause rapid p53 protein increases but resulted in delayed increases in p53 protein levels temporally correlated with the appearance of DNA strand breaks. Finally, we concluded that DNA strand breaks were sufficient for initiating p53-dependent signal transduction after finding that introduction of nucleases into cells by electroporation stimulated rapid p53 protein elevations. While DNA strand breaks appeared to be capable of triggering p53 induction, DNA lesions other than strand breaks did not. Exposure of normal cells and excision repair-deficient xeroderma pigmentosum cells to low doses of UV light, under conditions in which thymine dimers appear but DNA replication-associated strand breaks were prevented, resulted in p53 induction attributable to DNA strand breaks associated with excision repair. Our data indicate that DNA strand breaks are sufficient and probably necessary for p53 induction in cells with wild-type p53 alleles exposed to DNA

  15. A Chromatin-Focused siRNA Screen for Regulators of p53-Dependent Transcription

    PubMed Central

    Sammons, Morgan A.; Zhu, Jiajun; Berger, Shelley L.

    2016-01-01

    The protein product of the Homo sapiens TP53 gene is a transcription factor (p53) that regulates the expression of genes critical for the response to DNA damage and tumor suppression, including genes involved in cell cycle arrest, apoptosis, DNA repair, metabolism, and a number of other tumorigenesis-related pathways. Differential transcriptional regulation of these genes is believed to alter the balance between two p53-dependent cell fates: cell cycle arrest or apoptosis. A number of previously identified p53 cofactors covalently modify and alter the function of both the p53 protein and histone proteins. Both gain- and loss-of-function mutations in chromatin modifiers have been strongly implicated in cancer development; thus, we sought to identify novel chromatin regulatory proteins that affect p53-dependent transcription and the balance between the expression of pro-cell cycle arrest and proapoptotic genes. We utilized an siRNA library designed against predicted chromatin regulatory proteins, and identified known and novel chromatin-related factors that affect both global p53-dependent transcription and gene-specific regulators of p53 transcriptional activation. The results from this screen will serve as a comprehensive resource for those interested in further characterizing chromatin and epigenetic factors that regulate p53 transcription. PMID:27334938

  16. Amphiregulin impairs apoptosis-stimulating protein 2 of p53 overexpression-induced apoptosis in hepatoma cells.

    PubMed

    Liu, Kai; Lin, Dongdong; Ouyang, Yabo; Pang, Lijun; Guo, Xianghua; Wang, Shanshan; Zang, Yunjin; Chen, Dexi

    2017-03-01

    Overexpression of apoptosis-stimulating protein 2 of p53 (ASPP2) induces apoptotic cell death in hepatoma cells (e.g. HepG2 cells) by enhancing the transactivation activity of p53, but long-term ASPP2 overexpression fails to induce more apoptosis since activation of the epidermal growth factor/epidermal growth factor receptor/SOS1 pathway impairs the pro-apoptotic role of ASPP2. In this study, in recombinant adenovirus-ASPP2-infected HepG2 cells, ASPP2 overexpression induces amphiregulin expression in a p53-dependent manner. Although amphiregulin initially contributes to ASPP2-induced apoptosis, it eventually impairs the pro-apoptotic function of ASPP2 by activating the epidermal growth factor/epidermal growth factor receptor/SOS1 pathway, leading to apoptosis resistance. Moreover, blocking soluble amphiregulin with a neutralizing antibody also significantly increased apoptotic cell death of HepG2 cells due to treatment with methyl methanesulfonate, cisplatin, or a recombinant p53 adenovirus, suggesting that the function of amphiregulin involved in inhibiting apoptosis may be a common mechanism by which hepatoma cells escape from stimulus-induced apoptosis. Thus, our data elucidate an apoptosis-evasion mechanism in hepatocellular carcinoma and have potential implications for hepatocellular carcinoma therapy.

  17. Polychlorinated Biphenyl Quinone Metabolite Promotes p53-Dependent DNA Damage Checkpoint Activation, S-Phase Cycle Arrest and Extrinsic Apoptosis in Human Liver Hepatocellular Carcinoma HepG2 Cells.

    PubMed

    Song, Xiufang; Li, Lingrui; Shi, Qiong; Lehmler, Hans-Joachim; Fu, Juanli; Su, Chuanyang; Xia, Xiaomin; Song, Erqun; Song, Yang

    2015-11-16

    Polychlorinated biphenyls (PCBs) are a group of persistent organic pollutants. The toxic behavior and mechanism of PCBs individuals and congeners have been extensively investigated. However, there is only limited information on their metabolites. Our previous studies have shown that a synthetic PCB metabolite, PCB29-pQ, causes oxidative damage with the evidence of cytotoxicity, genotoxicity, and mitochondrial-derived intrinsic apoptosis. Here, we investigate the effects of PCB29-pQ on DNA damage checkpoint activation, cell cycle arrest, and death receptor-related extrinsic apoptosis in human liver hepatocellular carcinoma HepG2 cells. Our results illustrate that PCB29-pQ increases the S-phase cell population by down-regulating cyclins A/D1/E, cyclin-dependent kinases (CDK 2/4/6), and cell division cycle 25A (CDC25A) and up-regulating p21/p27 protein expressions. PCB29-pQ also induces apoptosis via the up-regulation of Fas/FasL and the activation of caspase 8/3. Moreover, p53 plays a pivotal role in PCB29-pQ-induced cell cycle arrest and apoptosis via the activation of ATM/Chk2 and ATR/Chk1 checkpoints. Cell cycle arrest and apoptotic cell death were attenuated by the pretreatment with antioxidant N-acetyl-cysteine (NAC). Taken together, these results demonstrate that PCB29-pQ induces oxidative stress and promotes p53-dependent DNA damage checkpoint activation, S-phase cycle arrest, and extrinsic apoptosis in HepG2 cells.

  18. A naturally occurring 4-bp deletion in the intron 4 of p53 creates a spectrum of novel p53 isoforms with anti-apoptosis function.

    PubMed

    Shi, Hui; Tao, Ting; Huang, Delai; Ou, Zhao; Chen, Jun; Peng, Jinrong

    2015-01-01

    p53 functions as a tumor suppressor by transcriptionally regulating the expression of genes involved in controlling cell proliferation or apoptosis. p53 and its isoform Δ133p53/Δ113p53 form a negative regulation loop in that p53 activates the expression of Δ133p53/Δ113p53 while Δ133p53/Δ113p53 specifically antagonizes p53 apoptotic activity. This pathway is especially important to safeguard the process of embryogenesis because sudden activation of p53 by DNA damage signals or developmental stress is detrimental to a developing embryo. Here we report the identification of five novel p53 isoforms. p53β is generated due to alternative splicing of the intron 8 of p53 while the other four, namely, TA2p53, TA3p53, TA4p53 and TA5p53, result from the combination of alternative splicing of intron 1 (within intron 4 of the p53 gene) of the Δ113p53 gene and a naturally occurring CATT 4 bp deletion within the alternative splicing product in zebrafish. The CATT 4 bp deletion creates four translation start codons which are in-frame to the open reading frame of Δ113p53. We also show that TAp53 shares the same promoter with Δ113p53 and functions to antagonize p53 apoptotic activity. The identification of Δ113p53/TA2/3/4/5p53 reveals a pro-survival mechanism which operates robustly during embryogenesis in response to the DNA-damage condition.

  19. Dendrosomal nanocurcumin and p53 overexpression synergistically trigger apoptosis in glioblastoma cells

    PubMed Central

    Keshavarz, Reihaneh; Bakhshinejad, Babak; Babashah, Sadegh; Baghi, Narges; Sadeghizadeh, Majid

    2016-01-01

    Objective(s): Glioblastoma is the most lethal tumor of the central nervous system. Here, we aimed to evaluate the effects of exogenous delivery of p53 and a nanoformulation of curcumin called dendrosomal curcumin (DNC), alone and in combination, on glioblastoma tumor cells. Materials and Methods: MTT assay was exploited to measure the viability of U87-MG cells against DNC treatment. Cells were separately subjected to DNC treatment and transfected with p53-containing vector and then were co-exposed to DNC and p53 overexpression[A GA1][B2]. Annexin-V-FLUOS staining followed by flow cytometry and real-time PCR were applied to examine apoptosis and analyze the expression levels of the genes involved in cell cycle and oncogenesis, respectively. Results: The results of cell viability assay through MTT indicated that DNC inhibits the proliferation of U87-MG cells in a time- and dose-dependent manner. Apoptosis evaluation revealed that p53 overexpression accompanied by DNC treatment can act in a synergistic manner to significantly enhance the number of apoptotic cells (90%) compared with their application alone (15% and 38% for p53 overexpression and DNC, respectively). Also, real-time PCR data showed that the concomitant exposure of cells to both DNC and p53 overexpression leads to an enhanced expression of GADD45 and a reduced expression of NF-κB and c-Myc. Conclusion: The findings of the current study suggest that our combination strategy, which merges two detached gene (p53) and drug (curcumin) delivery systems into an integrated platform, may represent huge potential as a novel and efficient modality for glioblastoma treatment. PMID:28096969

  20. UV-A Irradiation Activates Nrf2-Regulated Antioxidant Defense and Induces p53/Caspase3-Dependent Apoptosis in Corneal Endothelial Cells

    PubMed Central

    Liu, Cailing; Vojnovic, Dijana; Kochevar, Irene E.; Jurkunas, Ula V.

    2016-01-01

    Purpose To examine whether Nrf2-regulated antioxidant defense and p53 are activated in human corneal endothelial cells (CEnCs) by environmental levels of ultraviolet A (UV-A), a known stimulator of oxidative stress. Methods Immortalized human CEnCs (HCEnCi) were exposed to UV-A fluences of 2.5, 5, 10, or 25 J/cm2, then allowed to recover for 3 to 24 hours. Control HCEnCi did not receive UV-A. Reactive oxygen species (ROS) were measured using H2DCFDA. Cell cytotoxicity was evaluated by lactate dehydrogenase (LDH) release. Levels of Nrf2, HO-1, NQO-1, p53, and caspase3 were detected by immunnoblotting or real-time PCR. Activated caspase3 was measured by immunoblotting and a fluorescence assay. Results Exposure of HCEnCi to 5, 10, and 25 J/cm2 UV-A increased ROS levels compared with controls. Nrf2, HO-1, and NQO-1 mRNA increased 1.7- to 3.2-fold at 3 and 6 hours after irradiation with 2.5 and 5 J/cm2 UV-A. At 6 hours post irradiation, UV-A (5 J/cm2) enhanced nuclear Nrf2 translocation. At 24 hours post treatment, UV-A (5, 10, and 25 J/cm2) produced a 1.8- to 2.8-fold increase in phospho-p53 and a 2.6- to 6.0-fold increase in activated caspase3 compared with controls, resulting in 20% to 42% cell death. Conclusions Lower fluences of UV-A induce Nrf2-regulated antioxidant defense and higher fluences activate p53 and caspase3, indicating that even near-environmental levels of UV-A may affect normal CEnCs. This data suggest that UV-A may especially damage cells deficient in antioxidant defense, and thus may be involved in the etiology of Fuchs' endothelial corneal dystrophy (FECD). PMID:27127932

  1. Effect of Thymoquinone on P53 Gene Expression and Consequence Apoptosis in Breast Cancer Cell Line

    PubMed Central

    Dastjerdi, Mehdi Nikbakht; Mehdiabady, Ebrahim Momeni; Iranpour, Farhad Golshan; Bahramian, Hamid

    2016-01-01

    Background: Nigella sativa has been a nutritional flavoring factor and natural treatment for many ailments for so many years in medical science. Earlier studies have been reported that thymoquinone (TQ), an active compound of its seed, contains anticancer properties. Previous studies have shown that TQ induces apoptosis in breast cancer cells but it is unclear the role of P53 in the apoptotic pathway. Hereby, this study reports the potency of TQ on expression of tumor suppressor gene P53 and apoptosis induction in breast cancer cell line Michigan Cancer Foundation-7 (MCF-7). Methods: MCF-7 cell line was cultured and treated with TQ, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was carried out for evaluating the half-maximal inhibitory concentration (IC50) values after 24 h of treatment. The percentage of apoptotic cells was measured by flow cytometry. Real-time polymerase chain reaction (PCR) was performed to estimate the messenger RNA expression of P53 in MCF-7 cell line at different times. Results: The IC50 value for the TQ in MCF-7 cells was 25 μM that determined using MTT assay. The flow cytometry and real-time PCR results showed that TQ could induce apoptosis in MCF-7 cells, and the P53 gene expression was dramatically up-regulated by ascending time, respectively. Hence, there was significant difference in 48 and 72 h. Conclusions: Our results demonstrated that TQ could induce apoptosis in MCF-7 cells through up-regulation of P53 expression in breast cancer cell line (MCF-7) by time-dependent manner. PMID:27141285

  2. Coxsackievirus B5 induced apoptosis of HeLa cells: Effects on p53 and SUMO

    SciTech Connect

    Gomes, Rogerio; Guerra-Sa, Renata; Arruda, Eurico

    2010-01-20

    Coxsackievirus B5 (CVB5), a human enterovirus of the family Picornaviridae, is a frequent cause of acute and chronic human diseases. The pathogenesis of enteroviral infections is not completely understood, and the fate of the CVB5-infected cell has a pivotal role in this process. We have investigated the CVB5-induced apoptosis of HeLa cells and found that it happens by the intrinsic pathway by a mechanism dependent on the ubiquitin-proteasome system, associated with nuclear aggregation of p53. Striking redistribution of both SUMO and UBC9 was noted at 4 h post-infection, simultaneously with a reduction in the levels of the ubiquitin-ligase HDM2. Taken together, these results suggest that CVB5 infection of HeLa cells elicit the intrinsic pathway of apoptosis by MDM2 degradation and p53 activation, destabilizing protein sumoylation, by a mechanism that is dependent on a functional ubiquitin-proteasome system.

  3. p53-Dependent suppression of genome instability in germ cells.

    PubMed

    Otozai, Shinji; Ishikawa-Fujiwara, Tomoko; Oda, Shoji; Kamei, Yasuhiro; Ryo, Haruko; Sato, Ayuko; Nomura, Taisei; Mitani, Hiroshi; Tsujimura, Tohru; Inohara, Hidenori; Todo, Takeshi

    2014-02-01

    Radiation increases mutation frequencies at tandem repeat loci. Germline mutations in γ-ray-irradiated medaka fish (Oryzias latipes) were studied, focusing on the microsatellite loci. Mismatch-repair genes suppress microsatellite mutation by directly removing altered sequences at the nucleotide level, whereas the p53 gene suppresses genetic alterations by eliminating damaged cells. The contribution of these two defense mechanisms to radiation-induced microsatellite instability was addressed. The spontaneous mutation frequency was significantly higher in msh2(-/-) males than in wild-type fish, whereas there was no difference in the frequency of radiation-induced mutations between msh2(-/-) and wild-type fish. By contrast, irradiated p53(-/-) fish exhibited markedly increased mutation frequencies, whereas their spontaneous mutation frequency was the same as that of wild-type fish. In the spermatogonia of the testis, radiation induced a high level of apoptosis both in wild-type and msh2(-/-) fish, but negligible levels in p53(-/-) fish. The results demonstrate that the msh2 and p53 genes protect genome integrity against spontaneous and radiation-induced mutation by two different pathways: direct removal of mismatches and elimination of damaged cells.

  4. Cyclosporine A Suppressed Glucose Oxidase Induced P53 Mitochondrial Translocation and Hepatic Cell Apoptosis through Blocking Mitochondrial Permeability Transition.

    PubMed

    Yu, Weihua; Zhang, Xiaodi; Liu, Jiangzheng; Wang, Xin; Li, Shuang; Liu, Rui; Liao, Nai; Zhang, Tao; Hai, Chunxu

    2016-01-01

    P53 is known as a transcription factor to control apoptotic cell death through regulating a series of target genes in nucleus. There is accumulating evidences show that p53 can directly induce cell apoptosis through transcription independent way at mitochondria. However, the mechanism by which p53 translocation into mitochondria in response to oxidative stress remains unclear. Here, glucose oxidase (GOX) was used to induce ROS generation in HepG2 cells and liver tissues of mice. The results showed that p53 was stabilized and translocated to mitochondria in a time and dose dependent manner after GOX exposure. Interestingly, as an inhibitor of mitochondrial permeability transition, cyclosporine A (CsA) was able to effectively reduce GOX mediated mitochondrial p53 distribution without influencing on the expression of p53 target genes including Bcl-2 and Bax. These indicated that CsA could just block p53 entering into mitochondria, but not affect p53-dependent transcription. Meanwhile, CsA failed to inhibit the ROS generation induced by GOX, which indicated that CsA had no antioxidant function. Moreover, GOX induced typical apoptosis characteristics including, mitochondrial dysfunction, accumulation of Bax and release of cytochrome C in mitochondria, accompanied with activation of caspase-9 and caspase-3. These processions were suppressed after pretreatment with CsA and pifithrin-μ (PFT-μ, a specific inhibitor of p53 mitochondrial translocation). In vivo, CsA was able to attenuate p53 mitochondrial distribution and protect mice liver against from GOX mediated apoptotic cell death. Taken together, these suggested that CsA could suppress ROS-mediated p53 mitochondrial distribution and cell apoptosis depended on its inhibition effect to mitochondrial permeability transition. It might be used to rescue the hepatic cell apoptosis in the patients with acute liver injury.

  5. Cyclosporine A Suppressed Glucose Oxidase Induced P53 Mitochondrial Translocation and Hepatic Cell Apoptosis through Blocking Mitochondrial Permeability Transition

    PubMed Central

    Yu, Weihua; Zhang, Xiaodi; Liu, Jiangzheng; Wang, Xin; Li, Shuang; Liu, Rui; Liao, Nai; Zhang, Tao; Hai, Chunxu

    2016-01-01

    P53 is known as a transcription factor to control apoptotic cell death through regulating a series of target genes in nucleus. There is accumulating evidences show that p53 can directly induce cell apoptosis through transcription independent way at mitochondria. However, the mechanism by which p53 translocation into mitochondria in response to oxidative stress remains unclear. Here, glucose oxidase (GOX) was used to induce ROS generation in HepG2 cells and liver tissues of mice. The results showed that p53 was stabilized and translocated to mitochondria in a time and dose dependent manner after GOX exposure. Interestingly, as an inhibitor of mitochondrial permeability transition, cyclosporine A (CsA) was able to effectively reduce GOX mediated mitochondrial p53 distribution without influencing on the expression of p53 target genes including Bcl-2 and Bax. These indicated that CsA could just block p53 entering into mitochondria, but not affect p53-dependent transcription. Meanwhile, CsA failed to inhibit the ROS generation induced by GOX, which indicated that CsA had no antioxidant function. Moreover, GOX induced typical apoptosis characteristics including, mitochondrial dysfunction, accumulation of Bax and release of cytochrome C in mitochondria, accompanied with activation of caspase-9 and caspase-3. These processions were suppressed after pretreatment with CsA and pifithrin-μ (PFT-μ, a specific inhibitor of p53 mitochondrial translocation). In vivo, CsA was able to attenuate p53 mitochondrial distribution and protect mice liver against from GOX mediated apoptotic cell death. Taken together, these suggested that CsA could suppress ROS-mediated p53 mitochondrial distribution and cell apoptosis depended on its inhibition effect to mitochondrial permeability transition. It might be used to rescue the hepatic cell apoptosis in the patients with acute liver injury. PMID:26884717

  6. Che-1 modulates the decision between cell cycle arrest and apoptosis by its binding to p53

    PubMed Central

    Desantis, A; Bruno, T; Catena, V; De Nicola, F; Goeman, F; Iezzi, S; Sorino, C; Gentileschi, M P; Germoni, S; Monteleone, V; Pellegrino, M; Kann, M; De Meo, P D; Pallocca, M; Höpker, K; Moretti, F; Mattei, E; Reinhardt, H C; Floridi, A; Passananti, C; Benzing, T; Blandino, G; Fanciulli, M

    2015-01-01

    The tumor suppressor p53 is mainly involved in the transcriptional regulation of a large number of growth-arrest- and apoptosis-related genes. However, a clear understanding of which factor/s influences the choice between these two opposing p53-dependent outcomes remains largely elusive. We have previously described that in response to DNA damage, the RNA polymerase II-binding protein Che-1/AATF transcriptionally activates p53. Here, we show that Che-1 binds directly to p53. This interaction essentially occurs in the first hours of DNA damage, whereas it is lost when cells undergo apoptosis in response to posttranscriptional modifications. Moreover, Che-1 sits in a ternary complex with p53 and the oncosuppressor Brca1. Accordingly, our analysis of genome-wide chromatin occupancy by p53 revealed that p53/Che1 interaction results in preferential transactivation of growth arrest p53 target genes over its pro-apoptotic target genes. Notably, exposure of Che-1+/− mice to ionizing radiations resulted in enhanced apoptosis of thymocytes, compared with WT mice. These results confirm Che-1 as an important regulator of p53 activity and suggest Che-1 to be a promising yet attractive drug target for cancer therapy. PMID:25996291

  7. Cisplatin induced apoptosis of ovarian cancer A2780s cells by activation of ERK/p53/PUMA signals.

    PubMed

    Song, Hao; Wei, Mei; Liu, Wenfen; Shen, Shulin; Li, Jiaqun; Wang, Liming

    2017-03-13

    Cisplatin (CDDP) is one of the most effective anticancer agents widely used in the treatment of solid tumors, including ovarian cancer. It is generally considered as a cytotoxic drug which kills cancer cells by causing DNA damage, and subsequently inducing apoptosis in cancer cells. However, the underlying mechanisms leading to cell apoptosis remain obscure. In this study, the signaling pathways involved in CDDP -induced apoptosis were examined using CDDP-sensitive ovarian cancer A2780s cells. A2780s cells were treated with CDDP (1.5-3 μg/ml) for 6 h, 12 h and 24 h. Using siRNA targeting P53 and PUMA, and a selective MEK inhibitor, PD98059 to examine the relation between ERK1/2 activation, p53 and PUMA expression after exposure to CDDP, and the effect on CDDP-induced apoptosis. The results shown that treatment of A2780s cells with CDDP (3 μg/ml) for 6-24 h induced apoptosis, resulting in the activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and accumulation of p53 and PUMA (p53 upregulated modulator of apoptosis) protein. Knockdown of P53 or PUMA by siRNA transfection blocked CDDP-induced apoptosis. Inhibition of ERK1/2 using PD98059, a selective MEK inhibitor, blocked the apoptotic cell death but prevented CDDP-induced accumulation of p53 and PUMA. Knockdown of P53 by siRNA transfection also blocked CDDP-induced accumulation of PUMA. We therefore concluded that CDDP activated ERK1/2 and induced-p53-dependent PUMA upregulation, resulting in triggering apoptosis in A2780s cells. Our study clearly demonstrates that the ERK1/2/p53/PUMA axis is related to CDDP-induced cell death in A2780s cells.

  8. Potential role of MLH1 in the induction of p53 and apoptosis by blocking transcription on damaged DNA templates.

    PubMed

    Yanamadala, Sunitha; Ljungman, Mats

    2003-08-01

    Defects in DNA mismatch repair (MMR) are common in human cancers, confer tolerance to certain types of chemotherapeutic agents, and lead to genomic instability. In addition to their mismatch-correcting roles during DNA replication, MMR proteins can bind to certain DNA lesions and signal p53 and apoptosis by an unknown mechanism. To further study the mechanism by which the MMR protein MLH1 is involved in the induction of p53 and apoptosis, we exposed the colon carcinoma cell line HCT116 (MLH1-deficient) and mlh1-corrected HCT116 sublines to alkylating agents or hydrogen peroxide (H2O2). It was found that while alkylating agents induced both apoptosis and phosphorylation of the Ser-15 site of p53 in a MLH1-dependent manner, induction of apoptosis, but not p53 phosphorylation, was MLH1 dependent following treatment with H2O2. The MLH1-dependent induction of p53 phosphorylation by alkylating agents did not appear to be cell cycle dependent, arguing against a futile repair mechanism operating during S phase as the sole mechanism for the MLH1-dependent DNA damage signaling. Importantly, we found that both alkylating agents and H2O2 caused significant inhibition of mRNA synthesis in MLH1-expressing but not in MLH1-deficient cells. These findings suggest a novel mechanism of MLH1 in the induction p53 and apoptosis by inhibiting RNA polymerase II-dependent transcription on damaged DNA templates.

  9. Induction of apoptosis in cancer cells through N-acetyl-l-leucine-modified polyethylenimine-mediated p53 gene delivery.

    PubMed

    Li, Zhiyuan; Zhang, Liu; Li, Quanshun

    2015-11-01

    Herein, N-acetyl-L-leucine-modified polyethylenimine was successfully constructed through the EDC/NHS-mediated coupling reaction and employed as vectors to accomplish p53 gene delivery using HeLa (p53wt) and PC-3 cells (p53null) as models. Compared with PEI25K, the derivatives exhibited lower cytotoxicity, protein adsorption and hemolytic activity, together with satisfactory pDNA condensation capability and gene transfection efficiency. After p53 transfection, MTT analysis confirmed that the cell proliferation was inhibited. Flow cytometric analysis showed that the derivative-mediated p53 delivery could induce stronger early apoptosis than PEI25K and Lipofectamine(2000). Further, PC-3 cells showed higher sensitivity to the exogenous p53 transfection than HeLa cells. The mechanism for inducing apoptosis was determined to be up-regulation of p53 expression at both mRNA and protein levels using RT-PCR and western blotting analysis. Expression level and activity analysis of caspase-3, -8 and -9, and mitochondrial membrane potential measurement revealed that p53 transfection mediated by these derivatives facilitated early apoptosis of tumor cells via a mitochondria-dependent apoptosis pathway. Thus, the derivatives showed potential as biocompatible carriers for realizing effective tumor gene therapy.

  10. Apigenin enhances the cisplatin cytotoxic effect through p53-modulated apoptosis

    PubMed Central

    Liu, Rui; Ji, Ping; Liu, Bin; Qiao, Haishi; Wang, Xia; Zhou, Likun; Deng, Ting; Ba, Yi

    2017-01-01

    Epidemiological and experimental evidence suggests that dietary flavonoids, including apigenin, have anticancer roles. Apigenin has been reported to elevate p53, a critical molecule in the induction of apoptosis. The present study aimed to investigate whether apigenin, a dietary flavonoid, improves the cytotoxic effect of cisplatin in a cancer cell culture system, and to elucidate the mechanism of this effect. Multiple tumor cell types were treated with apigenin, cisplatin or both drugs. Cell viability was evaluated, and the cytotoxic effect was determined biochemically and microscopically. Treatment with apigenin increased cisplatin-induced DNA damage and the apoptosis of tumor cells in a p53-dependent manner. Apigenin, when used with cisplatin, inhibited cell proliferation and promoted mitogen-activated protein kinase activation and subsequent p53 phosphorylation, leading to p53 accumulation and upregulation of proapoptotic proteins. Cisplatin is one of the most commonly used chemotherapeutic drugs for malignant tumors, but resistance to this drug occurs. The current results therefore demonstrate that dietary flavonoids may diminish the resistance of cancers to cisplatin. PMID:28356995

  11. Threshold Level of p53 Required for the Induction of Apoptosis in X-Irradiated MOLT-4 Cells

    SciTech Connect

    Nakano, Hisako . E-mail: nakano@rinshoken.or.jp; Yonekawa, Hiromichi; Shinohara, Kunio

    2007-07-01

    Purpose: To determine the threshold level for the initiation of apoptosis by studying the quantitative aspect of p53 response to DNA damage in individual cells, to better understand the process in X-ray-induced p53-dependent apoptosis. Methods and Materials: Time-sequential changes in p53 protein level were obtained for X-irradiated MOLT-4 cells using flow cytometry and analyzed. Results: The changes in the cellular frequency distribution pattern of p53 content could be divided into two parts at a certain p53 level. The p53 vs. side-scatter in flow cytometry showed the sequential changes of p53 increase followed by an increase in cell death. On the basis of these results we determined a threshold level of p53 for the initiation of apoptosis. The level was estimated to be (1.08 {+-} 0.05) x 10{sup 5} molecules per cell, which was approximately threefold higher than the mean content of control cells. The minimum times for p53 level to reach this threshold level were independent of X-ray dose and 1.4-1.6 h. The times for the signal transduction from the p53 accumulation to disruption of the mitochondrial membrane potential, caspase-3 activation, and cell death were 1.6, 2.1, and 2.8 h, respectively. Conclusions: The threshold level of p53 for the initiation of apoptosis and the time sequence in the course of apoptotic events were determined in X-irradiated MOLT-4 cells.

  12. Age associated high level of major vault protein is p53 dependent.

    PubMed

    An, Hong-Joo; Ryu, Sung-Jin; Kim, Sung-Young; Choi, Hae-Ri; Chung, Jun-Ho; Park, Sang-Chul

    2009-07-01

    Major vault protein (MVP) represents the main component of vaults and has been linked to multi-drug resistance (MDR) in cancer cells. We previously reported that MVP plays an important role in the resistance of senescent human diploid fibroblasts (HDFs) to apoptosis and also that MVP expression is markedly reduced in young HDFs but not in senescent HDFs. In this study, designed to elucidate the regulation of MVP in young and senescent HDFs, we examined the levels of transcriptional factors for the MVP gene, which revealed that among the putative transcriptional factors, p53 decreased only in young HDFs, but not in senescent HDFs in response to H(2)O(2) treatment in the same mode as the expression of MVP. Moreover, the phosphorylation status of p53 increased only in senescent HDFs but not in young HDFs in response to H(2)O(2) treatment. Therefore, we tested the possibility of MVP regulation by p53 status. MVP is upregulated in p53 over-expressing young HDFs, while MVP is downregulated in p53-specific small interfering RNA (siRNA)-transfected senescent HDFs, which suggests that the expression of MVP would be p53 dependent. Furthermore, using chromatin immunoprecipitation (ChIP) assay, we observed that p53 binds directly to the MVP promoter. Taken together, these results suggest that p53 would be a major transcriptional factor for MVP gene expression. (c) 2009 John Wiley & Sons, Ltd.

  13. Identification of LDH-A as a therapeutic target for cancer cell killing via (i) p53/NAD(H)-dependent and (ii) p53-independent pathways

    PubMed Central

    Allison, S J; Knight, J R P; Granchi, C; Rani, R; Minutolo, F; Milner, J; Phillips, R M

    2014-01-01

    ) through induction of apoptosis, irrespective of cancer cell p53 status and (ii) as a part of a combinatorial approach with redox-sensitive anticancer drugs via a novel p53/NAD(H)-dependent mechanism. PMID:24819061

  14. HAMLET triggers apoptosis but tumor cell death is independent of caspases, Bcl-2 and p53.

    PubMed

    Hallgren, O; Gustafsson, L; Irjala, H; Selivanova, G; Orrenius, S; Svanborg, C

    2006-02-01

    HAMLET (Human alpha-lactalbumin Made Lethal to Tumor cells) triggers selective tumor cell death in vitro and limits tumor progression in vivo. Dying cells show features of apoptosis but it is not clear if the apoptotic response explains tumor cell death. This study examined the contribution of apoptosis to cell death in response to HAMLET. Apoptotic changes like caspase activation, phosphatidyl serine externalization, chromatin condensation were detected in HAMLET-treated tumor cells, but caspase inhibition or Bcl-2 over-expression did not prolong cell survival and the caspase response was Bcl-2 independent. HAMLET translocates to the nuclei and binds directly to chromatin, but the death response was unrelated to the p53 status of the tumor cells. p53 deletions or gain of function mutations did not influence the HAMLET sensitivity of tumor cells. Chromatin condensation was partly caspase dependent, but apoptosis-like marginalization of chromatin was also observed. The results show that tumor cell death in response to HAMLET is independent of caspases, p53 and Bcl-2 even though HAMLET activates an apoptotic response. The use of other cell death pathways allows HAMLET to successfully circumvent fundamental anti-apoptotic strategies that are present in many tumor cells.

  15. Cisplatin modulates B-cell translocation gene 2 to attenuate cell proliferation of prostate carcinoma cells in both p53-dependent and p53-independent pathways.

    PubMed

    Chiang, Kun-Chun; Tsui, Ke-Hung; Chung, Li-Chuan; Yeh, Chun-Nan; Feng, Tsui-Hsia; Chen, Wen-Tsung; Chang, Phei-Lang; Chiang, Hou-Yu; Juang, Horng-Heng

    2014-07-01

    Cisplatin is a widely used anti-cancer drug. The B-cell translocation gene 2 (BTG2) is involved in the cell cycle transition regulation. We evaluated the cisplatin effects on prostate cancer cell proliferation and the expressions of BTG2, p53, androgen receptor (AR) and prostate specific antigen (PSA) in prostate carcinoma, p53 wild-type LNCaP or p53-null PC-3, cells. Cisplatin treatments attenuated cell prostate cancer cell growth through inducing Go/G1 cell cycle arrest in lower concentration and apoptosis at higher dosage. Cisplatin treatments enhanced p53 and BTG2 expression, repressed AR and PSA expression, and blocked the activation of androgen on the PSA secretion in LNCaP cells. BTG2 knockdown in LNCaP cells attenuated cisplatin-mediated growth inhibition. Cisplatin enhanced BTG2 gene expression dependent on the DNA fragment located within -173 to -82 upstream of BTG2 translation initiation site in prostate cancer cells. Mutation of the p53 response element from GGGCAGAGCCC to GGGCACC or mutation of the NFκB response element from GGAAAGTCC to GGAAAGGAA by site-directed mutagenesis abolished the stimulation of cisplatin on the BTG2 promoter activity in LNCaP or PC-3 cells, respectively. Our results indicated that cisplatin attenuates prostate cancer cell proliferation partly mediated by upregulation of BTG2 through the p53-dependent pathway or p53-independent NFκB pathway.

  16. Decrease of mitochondrial p53 during late apoptosis is linked to its dephosphorylation on serine 20

    PubMed Central

    Castrogiovanni, Cédric; Vandaudenard, Marie; Waterschoot, Béranger; De Backer, Olivier; Dumont, Patrick

    2015-01-01

    Following a genotoxic stress, the tumor suppressor p53 translocates to mitochondria to take part in direct induction of apoptosis, via interaction with BCL-2 family members such as BAK and BAX. We determined the kinetics of the mitochondrial translocation of p53 in HCT-116 and PA-1 cells exposed to different genotoxic stresses (doxorubicin, camptothecin, UVB). This analysis revealed an early escalation in the amount of mitochondrial p53, followed by a peak amount and a decrease of mitochondrial p53 at later time points. We show that the serine 20 phosphorylated form of p53 is present at the mitochondria and that the decrease of p53 mitochondrial level during late apoptosis correlates with a decrease of Ser-20 phosphorylation. Moreover, the S20A p53 mutant translocates well to mitochondria after a genotoxic stress but its mitochondrial localization is very low during late apoptosis when compared to wt p53. The S20A mutant also appears to be compromised for interaction with BAK. We propose here that the level of serine 20 phosphorylation is influential on p53 mitochondrial localization during late apoptosis. Additionally, we report the presence of a new ≃45 kDa caspase-cleaved fragment of p53 in the cytosolic and mitochondrial fractions of apoptotic cells. PMID:26252178

  17. Myocyte apoptosis during acute myocardial infarction in the mouse localizes to hypoxic regions but occurs independently of p53.

    PubMed Central

    Bialik, S; Geenen, D L; Sasson, I E; Cheng, R; Horner, J W; Evans, S M; Lord, E M; Koch, C J; Kitsis, R N

    1997-01-01

    Significant numbers of myocytes die by apoptosis during myocardial infarction. The molecular mechanism of this process, however, remains largely unexplored. To facilitate a molecular genetic analysis, we have developed a model of ischemia-induced cardiac myocyte apoptosis in the mouse. Surgical occlusion of the left coronary artery results in apoptosis, as indicated by the presence of nucleosome ladders and in situ DNA strand breaks. Apoptosis occurs mainly in cardiac myocytes, and is shown for the first time to be limited to hypoxic regions during acute infarction. Since hypoxia-induced apoptosis in other cell types is dependent on p53, and p53 is induced by hypoxia in cardiac myocytes, we investigated the necessity of p53 for myocyte apoptosis during myocardial infarction. Myocyte apoptosis occurs as readily, however, in the hearts of mice nullizygous for p53 as in wild-type littermates. These data demonstrate the existence of a p53-independent pathway that mediates myocyte apoptosis during myocardial infarction. PMID:9294101

  18. Chk2 regulates transcription-independent p53-mediated apoptosis in response to DNA damage

    SciTech Connect

    Chen Chen; Shimizu, Shigeomi; Tsujimoto, Yoshihide; Motoyama, Noboru . E-mail: motoyama@nils.go.jp

    2005-07-29

    The tumor suppressor protein p53 plays a central role in the induction of apoptosis in response to genotoxic stress. The protein kinase Chk2 is an important regulator of p53 function in mammalian cells exposed to ionizing radiation (IR). Cells derived from Chk2-deficient mice are resistant to the induction of apoptosis by IR, and this resistance has been thought to be a result of the defective transcriptional activation of p53 target genes. It was recently shown, however, that p53 itself and histone H1.2 translocate to mitochondria and thereby induces apoptosis in a transcription-independent manner in response to IR. We have now examined whether Chk2 also regulates the transcription-independent induction of apoptosis by p53 and histone H1.2. The reduced ability of IR to induce p53 stabilization in Chk2-deficient thymocytes was associated with a marked impairment of p53 and histone H1 translocation to mitochondria. These results suggest that Chk2 regulates the transcription-independent mechanism of p53-mediated apoptosis by inducing stabilization of p53 in response to IR.

  19. Genome-Wide Expression Analysis Identifies a Modulator of Ionizing Radiation-Induced p53-Independent Apoptosis in Drosophila melanogaster

    PubMed Central

    van Bergeijk, Petra; Heimiller, Joseph; Uyetake, Lyle; Su, Tin Tin

    2012-01-01

    Tumor suppressor p53 plays a key role in DNA damage responses in metazoa, yet more than half of human tumors show p53 deficiencies. Therefore, understanding how therapeutic genotoxins such as ionizing radiation (IR) can elicit DNA damage responses in a p53-independent manner is of clinical importance. Drosophila has been a good model to study the effects of IR because DNA damage responses as well as underlying genes are conserved in this model, and because streamlined gene families make loss-of-function analyses feasible. Indeed, Drosophila is the only genetically tractable model for IR-induced, p53-independent apoptosis and for tissue regeneration and homeostasis after radiation damage. While these phenomenon occur only in the larvae, all genome-wide gene expression analyses after irradiation to date have been in embryos. We report here the first analysis of IR-induced, genome-wide gene expression changes in wild type and p53 mutant Drosophila larvae. Key data from microarrays were confirmed by quantitative RT-PCR. The results solidify the central role of p53 in IR-induced transcriptome changes, but also show that nearly all changes are made of both p53-dependent and p53-independent components. p53 is found to be necessary not just for the induction of but also for the repression of transcript levels for many genes in response to IR. Furthermore, Functional analysis of one of the top-changing genes, EF1a-100E, implicates it in repression of IR-induced p53-independent apoptosis. These and other results support the emerging notion that there is not a single dominant mechanism but that both positive and negative inputs collaborate to induce p53-independent apoptosis in response to IR in Drosophila larvae. PMID:22666323

  20. The Fusion Protein of Respiratory Syncytial Virus Triggers p53-Dependent Apoptosis▿

    PubMed Central

    Eckardt-Michel, Julia; Lorek, Markus; Baxmann, Diane; Grunwald, Thomas; Keil, Günther M.; Zimmer, Gert

    2008-01-01

    Infection with respiratory syncytial virus (RSV) frequently causes inflammation and obstruction of the small airways, leading to severe pulmonary disease in infants. We show here that the RSV fusion (F) protein, an integral membrane protein of the viral envelope, is a strong elicitor of apoptosis. Inducible expression of F protein in polarized epithelial cells triggered caspase-dependent cell death, resulting in rigorous extrusion of apoptotic cells from the cell monolayer and transient loss of epithelial integrity. A monoclonal antibody directed against F protein inhibited apoptosis and was also effective if administered to A549 lung epithelial cells postinfection. F protein expression in epithelial cells caused phosphorylation of tumor suppressor p53 at serine 15, activation of p53 transcriptional activity, and conformational activation of proapoptotic Bax. Stable expression of dominant-negative p53 or p53 knockdown by RNA interference inhibited the apoptosis of RSV-infected A549 cells. HEp-2 tumor cells with low levels of p53 were not sensitive to RSV-triggered apoptosis. We propose a new model of RSV disease with the F protein as an initiator of epithelial cell shedding, airway obstruction, secondary necrosis, and consequent inflammation. This makes the RSV F protein a key target for the development of effective postinfection therapies. PMID:18216092

  1. 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.

  2. 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.

  3. 2.45 GHz Microwave Radiation Impairs Learning and Spatial Memory via Oxidative/Nitrosative Stress Induced p53-Dependent/Independent Hippocampal Apoptosis: Molecular Basis and Underlying Mechanism.

    PubMed

    Shahin, Saba; Banerjee, Somanshu; Singh, Surya Pal; Chaturvedi, Chandra Mohini

    2015-12-01

    A close association between microwave (MW) radiation exposure and neurobehavioral disorders has been postulated but the direct effects of MW radiation on central nervous system still remains contradictory. This study was performed to understand the effect of short (15 days) and long-term (30 and 60 days) low-level MW radiation exposure on hippocampus with special reference to spatial learning and memory and its underlying mechanism in Swiss strain male mice, Mus musculus. Twelve-weeks old mice were exposed to 2.45 GHz MW radiation (continuous-wave [CW] with overall average power density of 0.0248 mW/cm(2) and overall average whole body specific absorption rate value of 0.0146 W/Kg) for 2 h/day over a period of 15, 30, and 60 days). Spatial learning and memory was monitored by Morris Water Maze. We have checked the alterations in hippocampal oxidative/nitrosative stress, neuronal morphology, and expression of pro-apoptotic proteins (p53 and Bax), inactive executioner Caspase- (pro-Caspase-3), and uncleaved Poly (ADP-ribose) polymerase-1 in the hippocampal subfield neuronal and nonneuronal cells (DG, CA1, CA2, and CA3). We observed that, short-term as well as long-term 2.45 GHz MW radiation exposure increases the oxidative/nitrosative stress leading to enhanced apoptosis in hippocampal subfield neuronal and nonneuronal cells. Present findings also suggest that learning and spatial memory deficit which increases with the increased duration of MW exposure (15 < 30 < 60 days) is correlated with a decrease in hippocampal subfield neuronal arborization and dendritic spines. These findings led us to conclude that exposure to CW MW radiation leads to oxidative/nitrosative stress induced p53-dependent/independent activation of hippocampal neuronal and nonneuronal apoptosis associated with spatial memory loss.

  4. Silver-based nanoparticles induce apoptosis in human colon cancer cells mediated through p53.

    PubMed

    Satapathy, Shakti Ranjan; Mohapatra, Purusottam; Preet, Ranjan; Das, Dipon; Sarkar, Biplab; Choudhuri, Tathagata; Wyatt, Michael D; Kundu, Chanakya Nath

    2013-08-01

    The authors have systematically investigated the anticancer potentiality of silver-based nanoparticles (AgNPs) and the mechanism underlying their biological activity in human colon cancer cells. Starch-capped AgNPs were synthesized, characterized and their biological activity evaluated through multiple biochemical assays. AgNPs decreased the growth and viability of HCT116 colon cancer cells. AgNP exposure increased apoptosis, as demonstrated by an increase in 4´,6-diamidino-2-phenylindole-stained apoptotic nuclei, BAX/BCL-XL ratio, cleaved poly(ADP-ribose) polymerase, p53, p21 and caspases 3, 8 and 9, and by a decrease in the levels of AKT and NF-κB. The cell population in the G1 phase decreased, and the S-phase population increased after AgNP treatment. AgNPs caused DNA damage and reduced the interaction between p53 and NF-κB. Interestingly, no significant alteration was noted in the levels of p21, BAX/BCL-XL and NF-κB after AgNP treatment in a p53-knockout HCT116 cell line. AgNPs are bona fide anticancer agents that act in a p53-dependent manner. Original submitted 16 March 2012; Revised submitted 25 August 2012; Published online 21 March 2013.

  5. Targeting of C-Terminal Binding Protein (CtBP) by ARF Results in p53-Independent Apoptosis

    PubMed Central

    Paliwal, Seema; Pande, Sandhya; Kovi, Ramesh C.; Sharpless, Norman E.; Bardeesy, Nabeel; Grossman, Steven R.

    2006-01-01

    ARF encodes a potent tumor suppressor that antagonizes MDM2, a negative regulator of p53. ARF also suppresses the proliferation of cells lacking p53, and loss of ARF in p53-null mice, compared with ARF or p53 singly null mice, results in a broadened tumor spectrum and decreased tumor latency. To investigate the mechanism of p53-independent tumor suppression by ARF, potential interacting proteins were identified by yeast two-hybrid screen. The antiapoptotic transcriptional corepressor C-terminal binding protein 2 (CtBP2) was identified, and ARF interactions with both CtBP1 and CtBP2 were confirmed in vitro and in vivo. Interaction with ARF resulted in proteasome-dependent CtBP degradation. Both ARF-induced CtBP degradation and CtBP small interfering RNA led to p53-independent apoptosis in colon cancer cells. ARF induction of apoptosis was dependent on its ability to interact with CtBP, and reversal of ARF-induced CtBP depletion by CtBP overexpression abrogated ARF-induced apoptosis. CtBP proteins represent putative targets for p53-independent tumor suppression by ARF. PMID:16508011

  6. Oxidized DJ-1 Inhibits p53 by Sequestering p53 from Promoters in a DNA-Binding Affinity-Dependent Manner

    PubMed Central

    Kato, Izumi; Maita, Hiroshi; Takahashi-Niki, Kazuko; Saito, Yoshiro; Noguchi, Noriko; Iguchi-Ariga, Sanae M. M.

    2013-01-01

    DJ-1 is an oncogene and the causative gene for familial Parkinson's disease. Although the oxidative status of DJ-1 at cysteine 106 (C106) is thought to affect all of the activities of DJ-1 and excess oxidation leads to the onset of various diseases, the precise molecular mechanisms underlying the effects of oxidation of DJ-1 on protein-protein interactions of DJ-1 remain unclear. In this study, we found that DJ-1 bound to the DNA-binding region of p53 in a manner dependent on the oxidation of C106. Of the p53 target genes, the expression level and promoter activity of the DUSP1 gene, but not those of the p21 gene, were increased in H2O2-treated DJ-1−/− cells and were decreased in wild-type DJ-1- but not C106S DJ-1-transfected H1299 cells through sequestration of p53 from the DUSP1 promoter by DJ-1. DUSP1 downregulated by oxidized DJ-1 activated extracellular signal-regulated kinase (ERK) and decreased apoptosis. The DUSP1 and p21 promoters harbor nonconsensus and consensus p53 recognition sequences, respectively, which have low affinity and high affinity for p53. However, DJ-1 inhibited p21 promoter activity exhibited by p53 mutants harboring low DNA-binding affinity but not by wild-type p53. These results indicate that DJ-1 inhibits the expression of p53 target genes and depend on p53 DNA-binding affinity and oxidation of DJ-1 C106. PMID:23149933

  7. Oxidized DJ-1 inhibits p53 by sequestering p53 from promoters in a DNA-binding affinity-dependent manner.

    PubMed

    Kato, Izumi; Maita, Hiroshi; Takahashi-Niki, Kazuko; Saito, Yoshiro; Noguchi, Noriko; Iguchi-Ariga, Sanae M M; Ariga, Hiroyoshi

    2013-01-01

    DJ-1 is an oncogene and the causative gene for familial Parkinson's disease. Although the oxidative status of DJ-1 at cysteine 106 (C106) is thought to affect all of the activities of DJ-1 and excess oxidation leads to the onset of various diseases, the precise molecular mechanisms underlying the effects of oxidation of DJ-1 on protein-protein interactions of DJ-1 remain unclear. In this study, we found that DJ-1 bound to the DNA-binding region of p53 in a manner dependent on the oxidation of C106. Of the p53 target genes, the expression level and promoter activity of the DUSP1 gene, but not those of the p21 gene, were increased in H(2)O(2)-treated DJ-1(-/-) cells and were decreased in wild-type DJ-1- but not C106S DJ-1-transfected H1299 cells through sequestration of p53 from the DUSP1 promoter by DJ-1. DUSP1 downregulated by oxidized DJ-1 activated extracellular signal-regulated kinase (ERK) and decreased apoptosis. The DUSP1 and p21 promoters harbor nonconsensus and consensus p53 recognition sequences, respectively, which have low affinity and high affinity for p53. However, DJ-1 inhibited p21 promoter activity exhibited by p53 mutants harboring low DNA-binding affinity but not by wild-type p53. These results indicate that DJ-1 inhibits the expression of p53 target genes and depend on p53 DNA-binding affinity and oxidation of DJ-1 C106.

  8. XI-011 enhances cisplatin-induced apoptosis by functional restoration of p53 in head and neck cancer.

    PubMed

    Roh, Jong-Lyel; Park, Jin Young; Kim, Eun Hye

    2014-11-01

    Head and neck cancer (HNC), one of the most common cancers worldwide, frequently involves mutation of the TP53 gene and dysregulation of the p53 pathway. Overexpression of MDM2 or MDM4 inactivates the tumor-suppressive function of p53. Restoration of p53 function that counteracts these p53 repressors can lead to in vivo tumor regression. Therefore, the present study assessed the ability of the small molecule p53 activator XI-011 (NSC146109) to induce apoptosis in HNC by restoring p53 function. We tested the effects of XI-011 treatment in HNC cell lines, either individually or in combination with cisplatin and assessed growth suppression, cell cycle arrest, and apoptosis. The drug effects on in vivo growth of HNC cells were examined in mice xenograft model. XI-011 exerted the highest growth suppression in tumor cells that overexpress MDM4, in which p53 is degraded. XI-011 treatment downregulated MDM4 mRNA and protein levels, and upregulated expression of proapoptotic genes and promoted apoptosis, in a dose-dependent manner. The apoptotic response was blocked by inhibition of p53 or expression of MDM4, demonstrating that the effects of XI-011 depend on p53 and MDM4. In combination treatments, XI-011 acted synergistically with cisplatin to inhibit growth of HNC cells in vitro and in vivo. MDM4 inhibition and functional restoration of p53 by XI-011 effectively enhanced cisplatin-induced cytotoxicity in HNC cells, an activity that suggests a promising strategy for treating HNC.

  9. PUMA binding induces partial unfolding within BCL-xL to disrupt p53 binding and promote apoptosis.

    PubMed

    Follis, Ariele Viacava; Chipuk, Jerry E; Fisher, John C; Yun, Mi-Kyung; Grace, Christy R; Nourse, Amanda; Baran, Katherine; Ou, Li; Min, Lie; White, Stephen W; Green, Douglas R; Kriwacki, Richard W

    2013-03-01

    Following DNA damage, nuclear p53 induces the expression of PUMA, a BH3-only protein that binds and inhibits the antiapoptotic BCL-2 repertoire, including BCL-xL. PUMA, unique among BH3-only proteins, disrupts the interaction between cytosolic p53 and BCL-xL, allowing p53 to promote apoptosis via direct activation of the BCL-2 effector molecules BAX and BAK. Structural investigations using NMR spectroscopy and X-ray crystallography revealed that PUMA binding induced partial unfolding of two α-helices within BCL-xL. Wild-type PUMA or a PUMA mutant incapable of causing binding-induced unfolding of BCL-xL equivalently inhibited the antiapoptotic BCL-2 repertoire to sensitize for death receptor-activated apoptosis, but only wild-type PUMA promoted p53-dependent, DNA damage-induced apoptosis. Our data suggest that PUMA-induced partial unfolding of BCL-xL disrupts interactions between cytosolic p53 and BCL-xL, releasing the bound p53 to initiate apoptosis. We propose that regulated unfolding of BCL-xL provides a mechanism to promote PUMA-dependent signaling within the apoptotic pathways.

  10. Cellular Oxidative Stress and the Control of Apoptosis by Wild-Type p53, Cytotoxic Compounds, and Cytokines

    NASA Astrophysics Data System (ADS)

    Lotem, Joseph; Peled-Kamar, Mira; Groner, Yoram; Sachs, Leo

    1996-08-01

    Apoptosis induced by wild-type p53 or cytotoxic compounds in myeloid leukemic cells can be inhibited by the cytokines interleukin 6, interleukin 3, granulocyte-macrophage colony-stimulating factor, and interferon γ and by antioxidants. The antioxidants and cytokines showed a cooperative protective effect against induction of apoptosis. Cells with a higher sensitivity to induction of apoptosis and required a higher cytokine concentration to inhibit apoptosis. Decreasing the intrinsic oxidative stress in cells by antioxidants thus inhibited apoptosis, whereas increasing this intrinsic stress by adding H2O2 enhanced apoptosis. Induction of apoptosis by wild-type p53 was not preceded by increased peroxide production or lipid peroxidation and the protective effect of cytokines was not associated with a decrease in these properties. The results indicate that the intrinsic degree of oxidative stress can regulate cell susceptibility to wild-type p53-dependent and p53-independent induction of apoptosis and the ability of cytokines to protect cells against apoptosis.

  11. Cellular oxidative stress and the control of apoptosis by wild-type p53, cytotoxic compounds, and cytokines.

    PubMed

    Lotem, J; Peled-Kamar, M; Groner, Y; Sachs, L

    1996-08-20

    Apoptosis induced by wild-type p53 or cytotoxic compounds in myeloid leukemic cells can be inhibited by the cytokines interleukin 6, interleukin 3, granulocyte-macrophage colony-stimulating factor, and interferon gamma and by antioxidants. The antioxidants and cytokines showed a cooperative protective effect against induction of apoptosis. Cells with a higher intrinsic level of peroxide production showed a higher sensitivity to induction of apoptosis and required a higher cytokine concentration to inhibit apoptosis. Decreasing the intrinsic oxidative stress in cells by antioxidants thus inhibited apoptosis, whereas increasing this intrinsic stress by adding H2O2 enhanced apoptosis. Induction of apoptosis by wild-type p53 was not preceded by increased peroxide production or lipid peroxidation and the protective effect of cytokines was not associated with a decrease in these properties. The results indicate that the intrinsic degree of oxidative stress can regulate cell susceptibility to wild-type p53-dependent and p53-independent induction of apoptosis and the ability of cytokines to protect cells against apoptosis.

  12. Absence of a p53 allele delays nitrogen mustard-induced early apoptosis and inflammation of murine skin.

    PubMed

    Inturi, Swetha; Tewari-Singh, Neera; Jain, Anil K; Roy, Srirupa; White, Carl W; Agarwal, Rajesh

    2013-09-15

    Bifunctional alkylating agent sulfur mustard (SM) and its analog nitrogen mustard (NM) cause DNA damage leading to cell death, and potentially activating inflammation. Transcription factor p53 plays a critical role in DNA damage by regulating cell cycle progression and apoptosis. Earlier studies by our laboratory demonstrated phosphorylation of p53 at Ser15 and an increase in total p53 in epidermal cells both in vitro and in vivo following NM exposure. To elucidate the role of p53 in NM-induced skin toxicity, we employed SKH-1 hairless mice harboring wild type (WT) or heterozygous p53 (p53+/-). Exposure to NM (3.2mg) caused a more profound increase in epidermal thickness and apoptotic cell death in WT relative to p53+/- mice at 24h. However, by 72h after exposure, there was a comparable increase in NM-induced epidermal cell death in both WT and p53+/- mice. Myeloperoxidase activity data showed that neutrophil infiltration was strongly enhanced in NM-exposed WT mice at 24h persisting through 72h of exposure. Conversely, robust NM-induced neutrophil infiltration (comparable to WT mice) was seen only at 72h after exposure in p53+/- mice. Similarly, NM-exposure strongly induced macrophage and mast cell infiltration in WT, but not p53+/- mice. Together, these data indicate that early apoptosis and inflammation induced by NM in mouse skin are p53-dependent. Thus, targeting this pathway could be a novel strategy for developing countermeasures against vesicants-induced skin injury.

  13. Absence of a p53 allele delays nitrogen mustard-induced early apoptosis and inflammation of murine skin

    PubMed Central

    Inturi, Swetha; Tewari-Singh, Neera; Jain, Anil K.; Roy, Srirupa; White, Carl W.; Agarwal, Rajesh

    2013-01-01

    Bifunctional alkylating agent sulfur mustard (SM) and its analog nitrogen mustard (NM) cause DNA damage leading to cell death, and potentially activating inflammation. Transcription factor p53 plays a critical role in DNA damage by regulating cell cycle progression and apoptosis. Earlier studies by our laboratory demonstrated phosphorylation of p53 at Ser15 and an increase in total p53 in epidermal cells both in vitro and in vivo following NM exposure. To elucidate the role of p53 in NM-induced skin toxicity, we employed SKH-1 hairless mice harboring wild type (WT) or heterozygous p53 (p53+/−). Exposure to NM (3.2 mg) caused a more profound increase in epidermal thickness and apoptotic cell death in WT relative to p53+/− mice at 24 h. However, by 72 h after exposure, there was a comparable increase in NM-induced epidermal cell death in both WT and p53+/− mice. Myeloperoxidase activity data showed that neutrophil infiltration was strongly enhanced in NM-exposed WT mice at 24 h persisting through 72 h of exposure. Conversely, robust NM-induced neutrophil infiltration (comparable to WT mice) was seen only at 72 h after exposure in p53+/− mice. Similarly, NM-exposure strongly induced macrophage and mast cell infiltration in WT, but not p53+/− mice. Together, these data indicate that early apoptosis and inflammation induced by NM in mouse skin are p53-dependent. Thus, targeting this pathway could be a novel strategy for developing countermeasures against vesicants-induced skin injury. PMID:23845566

  14. The absence of Ser389 phosphorylation in p53 affects the basal gene expression level of many p53-dependent genes and alters the biphasic response to UV exposure in mouse embryonic fibroblasts.

    PubMed

    Bruins, Wendy; Bruning, Oskar; Jonker, Martijs J; Zwart, Edwin; van der Hoeven, Tessa V; Pennings, Jeroen L A; Rauwerda, Han; de Vries, Annemieke; Breit, Timo M

    2008-03-01

    Phosphorylation is important in p53-mediated DNA damage responses. After UV irradiation, p53 is phosphorylated specifically at murine residue Ser389. Phosphorylation mutant p53.S389A cells and mice show reduced apoptosis and compromised tumor suppression after UV irradiation. We investigated the underlying cellular processes by time-series analysis of UV-induced gene expression responses in wild-type, p53.S389A, and p53(-/-) mouse embryonic fibroblasts. The absence of p53.S389 phosphorylation already causes small endogenous gene expression changes for 2,253, mostly p53-dependent, genes. These genes showed basal gene expression levels intermediate to the wild type and p53(-/-), possibly to readjust the p53 network. Overall, the p53.S389A mutation lifts p53-dependent gene repression to a level similar to that of p53(-/-) but has lesser effect on p53-dependently induced genes. In the wild type, the response of 6,058 genes to UV irradiation was strictly biphasic. The early stress response, from 0 to 3 h, results in the activation of processes to prevent the accumulation of DNA damage in cells, whereas the late response, from 12 to 24 h, relates more to reentering the cell cycle. Although the p53.S389A UV gene response was only subtly changed, many cellular processes were significantly affected. The early response was affected the most, and many cellular processes were phase-specifically lost, gained, or altered, e.g., induction of apoptosis, cell division, and DNA repair, respectively. Altogether, p53.S389 phosphorylation seems essential for many p53 target genes and p53-dependent processes.

  15. M-ds-P21 induces cell apoptosis in bladder cancer T24 cells through P53 independent pathway.

    PubMed

    Wang, Haifeng; Liu, Wujiang; Jin, Jie; Zhou, Liqun; Liang, Lili; Guo, Yinglu

    2013-01-01

    To investigate the effect of M-ds-P21 on the apoptosis of bladder cancer T24 cells and its potential mechanism. Effect of M-ds-P21 on T24 cells were assessed by cell morphology and Western blot. Apoptosis was quantified by Annexin-V flow-cytometry analysis. To uncover the role of P53 in M-ds-P21-mediated apoptosis of T24 cells, we knocked down P53 before treating cells with M-ds-P21, and then assayed P21 and apoptosis-related protein by Western blot. To uncover the mechanism by which M-ds-P21 played stronger effect than ds-P21, we performed confocal microscope analyses. Both M-ds-P21 and ds-P21 treatment changed the cell morphology, leading to cell apoptosis after 3 days. Apoptosis induced by M-ds-P21 and ds-P21 treatment is not P53-dependent but caspase-dependent. Compared with ds-P21, M-ds-P21 significantly increased the bioavailability of ds-RNA in T24 cells. M-ds-P21 treatment induces more apoptotic population than ds-P21 does. The mechanism for stronger effect of M-ds-P21 is partly due to the enhanced bioavailability of ds-RNA in human bladder cancer T24 cells, and not P53-dependent but caspase-dependent.

  16. 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

  17. Phosphorylation of p53 by TAF1 inactivates p53-dependent transcription in the DNA damage response

    PubMed Central

    Wu, Yong; Lin, Joy C.; Piluso, Landon G.; Dhahbi, Joseph M.; Bobadilla, Selene; Spindler, Stephen R.; Liu, Xuan

    2014-01-01

    Summary While p53 activation has long been studied, the mechanisms by which its targets genes are restored to their pre-activation state are less clear. We report here that TAF1 phosphorylates p53 at Thr55, leading to dissociation of p53 from the p21 promoter and inactivation of transcription late in the DNA damage response. We further show that cellular ATP level might act as a molecular switch for Thr55 phosphorylation on the p21 promoter, indicating that TAF1 is a cellular ATP sensor. Upon DNA damage, cells undergo PARP-1-dependent ATP depletion, which is correlated with reduced TAF1 kinase activity and Thr55 phosphorylation, resulting in p21 activation. As cellular ATP levels recover, TAF1 is able to phosphorylate p53 on Thr55, which leads to dissociation of p53 from the p21 promoter. ChIP-sequencing analysis reveals p53 dissociates from promoters genome-wide as cells recover from DNA damage, suggesting the general nature of this mechanism. PMID:24289924

  18. p53 causes butein-mediated apoptosis of chronic myeloid leukemia cells

    PubMed Central

    WOO, SANG-MI; CHOI, YOUN KYNUG; KIM, AH JEONG; CHO, SUNG-GOOK; KO, SEONG-GYU

    2016-01-01

    Progression of chronic myeloid leukemia, marked by the oncogenic Bcr-Abl mutation, is tightly associated with an alteration of the p53 pathway. It is known that butein extracted from various plants represses cancer growth. Although the anticancer effects of butein are widely accepted, the mechanisms by which butein induces apoptosis of chronic myeloid leukemia cells remains to be elucidated. The present study demonstrated that butein-induced apoptosis was mediated by p53. KBM5 chronic myeloid leukemia (CML) cells expressing wild-type p53 were more sensitive to butein compared with p53-null K562 CML cells in terms of apoptotic cell death. In addition, butein arrested KBM5 cells at S-phase and altered the expression levels of certain cyclins and the p53-downstream targets, MDM2 and p21. In addition, while butein reduced the protein expression of MDM2 in the KBM5 and K562 cells, it resulted in proteasome-independent MDM2 degradation in p53-expressing KBM5 cells, however, not in p53-null K562 cells. Therefore, the present study suggested that p53 causes the butein-mediated apoptosis of leukemic cells. PMID:26676515

  19. Expression of survivin and p53 modulates honokiol-induced apoptosis in colorectal cancer cells.

    PubMed

    Lai, Ying-Jiun; Lin, Chien-I; Wang, Chia-Lin; Chao, Jui-I

    2014-11-01

    Honokiol is a small biphenolic compound, which exerts antitumor activities; however, the precise mechanism of honokiol-induced apoptosis in the human colorectal cancer cells remains unclear. Here, we show that survivin and p53 display the opposite role on the regulation of honokiol-induced apoptosis in the human colorectal cancer cells. Honokiol induced the cell death and apoptosis in various colorectal cancer cell lines. Moreover, honokiol elicited the extrinsic death receptor pathway of DR5 and caspase 8 and the intrinsic pathway of caspase 9. The common intrinsic and extrinsic downstream targets of activated caspase 3 and PARP protein cleavage were induced by honokiol. Interestingly, honokiol reduced anti-apoptotic survivin protein and gene expression. Transfection with a green fluorescent protein (GFP)-survivin-expressed vector increased the colorectal cancer cell viability and resisted the honokiol-induced apoptosis. Meantime, honokiol increased total p53 and the phosphorylated p53 proteins at Ser15 and Ser46. The p53-wild type colorectal cancer cells were exhibited greater cytotoxicity, apoptosis and survivin reduction than the p53-null cancer cells after treatment with honokiol. Together, these findings demonstrate that the existence of survivin and p53 can modulate the honokiol-induced apoptosis in the human colorectal cancer cells. © 2014 Wiley Periodicals, Inc.

  20. p53 induced growth arrest versus apoptosis and its modulation by survival cytokines.

    PubMed

    Liebermann, Dan A; Hoffman, Barbara; Vesely, Diana

    2007-01-15

    The p53 tumor suppressor gene encodes for a transcription factor that plays a seminal role in the response of mammalian cells to physiological and environmental stress. p53 has been implicated as a major mediator of cell cycle arrest and/or apoptosis in the response of mammalian cells to stress stimuli. It appears that several determinants, including cell type, the presence or absence of survival factors in the external environment, the extent of DNA damage, the level of p53 and post-translational modifications, are involved in the choice between cell cycle arrest and apoptosis. Ongoing work on the biological functions of the p53 tumor suppressor in different cell types and under various physiological conditions will help to unravel the complex nature of molecular circuits that orchestrate the biological response to p53 activation.

  1. Bisdemethoxycurcumin enhances X-ray-induced apoptosis possibly through p53/Bcl-2 pathway.

    PubMed

    Enomoto, Atsushi; Yamada, Junko; Morita, Akinori; Miyagawa, Kiyoshi

    2017-03-01

    Bisdemethoxycurcumin (BDMC), which is isolated from the rhizomes of Curcuma longa, has anti-inflammatory and anti-carcinogenic activities. Here we found that BDMC enhanced X-ray-induced apoptosis in human T-cell leukemia MOLT-4 cells. Knockdown of p53 significantly attenuated the radiosensitizing effect of BDMC. However, BDMC did not enhance X-ray-mediated activation of the p53 signaling pathway via p53's transactivation or mitochondrial translocation. On the other hand, BDMC promoted the X-ray-induced dephosphorylation at Ser 70 in Bcl-2's flexible loop regulatory domain and Bcl-2 binding to p53. Overexpressing Bcl-2 completely blocked the BDMC's radiosensitization effect. Our results indicate that BDMC stimulates the dephosphorylation and p53-binding activity of Bcl-2 and suggest that BDMC may induce a neutralization of Bcl-2's anti-apoptotic function, thereby enhancing X-ray-induced apoptosis.

  2. Transduction of Recombinant M3-p53-R12 Protein Enhances Human Leukemia Cell Apoptosis

    PubMed Central

    Lu, Tsung Chi; Zhao, Guan- Hao; Chen, Yao Yun; Chien, Chia-Ying; Huang, Chi-Hung; Lin, Kwang Hui; Chen, Shen Liang

    2016-01-01

    Tumor suppressor protein p53 plays important roles in initiating cell cycle arrest and promoting tumor cell apoptosis. Previous studies have shown that p53 is either mutated or defective in approximately 50% of human cancers; therefore restoring normal p53 activity in cancer cells might be an effective anticancer therapeutic approach. Herein, we designed a chimeric p53 protein flanked with the MyoD N-terminal transcriptional activation domain (amino acids 1-62, called M3) and a poly-arginine (R12) cell penetrating signal in its N-and C-termini respectively. This chimeric protein, M3-p53-R12, can be expressed in E. coli and purified using immobilized metal ion chromatography followed by serial refolding dialysis. The purified M3-p53-R12 protein retains DNA-binding activity and gains of cell penetrating ability. Using MTT assay, we demonstrated that M3-p53-R12 inhibited the growth of K562, Jurkat as well as HL-60 leukemia cells carrying mutant p53 genes. Results from FACS analysis also demonstrated that transduction of M3-p53-R12 protein induced cell cycle arrest of these leukemia cells. Of special note, M3-p53-R12 has no apoptotic effect on normal mesenchymal stem cells (MSC) and leukocytes, highlighting its differential effects on normal and tumor cells. To sum up, our results reveal that purified recombinant M3-p53-R12 protein has functions of suppressing the leukemia cell lines' proliferation and launching cell apoptosis, suggesting the feasibility of using M3-p53-R12 protein as an anticancer drug. In the future we will test whether this chimeric protein can preferentially trigger the death of malignant cancer cells without affecting normal cells in animals carrying endogenous or xenographic tumors. PMID:27390612

  3. Glucocorticoid receptor activation inhibits p53-induced apoptosis of MCF10Amyc cells via induction of protein kinase Cε.

    PubMed

    Aziz, Moammir H; Shen, Hong; Maki, Carl G

    2012-08-24

    Glucocorticoid receptor (GR) is a ligand-dependent transcription factor that can promote apoptosis or survival in a cell-specific manner. Activated GR has been reported to inhibit apoptosis in mammary epithelial cells and breast cancer cells by increasing pro-survival gene expression. In this study, activated GR inhibited p53-dependent apoptosis in MCF10A cells and human mammary epithelial cells that overexpress the MYC oncogene. Specifically, GR agonists hydrocortisone or dexamethasone inhibited p53-dependent apoptosis induced by cisplatin, ionizing radiation, or the MDM2 antagonist Nutlin-3. In contrast, the GR antagonist RU486 sensitized the cells to apoptosis by these agents. Apoptosis inhibition was associated with maintenance of mitochondrial membrane potential, diminished caspase-3 and -7 activation, and increased expression at both the mRNA and protein level of the anti-apoptotic PKC family member PKCε. Knockdown of PKCε via siRNA targeting reversed the protective effect of dexamethasone and restored apoptosis sensitivity. These data provide evidence that activated GR can inhibit p53-dependent apoptosis through induction of the anti-apoptotic factor PKCε.

  4. UVC-induced apoptosis in Dubca cells is independent of JNK activation and p53{sup Ser-15} phosphorylation

    SciTech Connect

    Chathoth, Shahanas; Thayyullathil, Faisal; Hago, Abdulkader; Shahin, Allen; Patel, Mahendra; Galadari, Sehamuddin

    2009-06-12

    Ultraviolet C (UVC) irradiation in mammalian cell lines activates a complex signaling network that leads to apoptosis. By using Dubca cells as a model system, we report the presence of a UVC-induced apoptotic pathway that is independent of c-Jun N-terminal kinases (JNKs) activation and p53 phosphorylation at Ser{sup 15}. Irradiation of Dubca cells with UVC results in a rapid JNK activation and phosphorylation of its downstream target c-Jun, as well as, phosphorylation of activating transcription factor 2 (ATF2). Pre-treatment with JNK inhibitor, SP600125, inhibited UVC-induced c-Jun phosphorylation without preventing UVC-induced apoptosis. Similarly, inhibition of UVC-induced p53 phosphorylation did not prevent Dubca cell apoptosis, suggesting that p53{sup Ser-15} phosphorylation is not associated with UVC-induced apoptosis signaling. The pan-caspase inhibitor z-VAD-fmk inhibited UVC-induced PARP cleavage, DNA fragmentation, and ultimately apoptosis of Dubca cells. Altogether, our study clearly indicates that UVC-induced apoptosis is independent of JNK and p53 activation in Dubca cells, rather, it is mediated through a caspase dependent pathway. Our findings are not in line with the ascribed critical role for JNKs activation, and downstream phosphorylation of targets such as c-Jun and ATF2 in UVC-induced apoptosis.

  5. Erybraedin C and bitucarpin A, two structurally related pterocarpans purified from Bituminaria bituminosa, induced apoptosis in human colon adenocarcinoma cell lines MMR- and p53-proficient and -deficient in a dose-, time-, and structure-dependent fashion.

    PubMed

    Maurich, Tiziana; Iorio, Mariacarla; Chimenti, Daniele; Turchi, Gino

    2006-02-01

    Pterocarpans, the second group of natural isoflavonoids, have received considerable interest on account of their medicinal properties. These drugs are employed as antitoxins, but display antifungal, antiviral and antibacterial properties as well. Erybraedin C and bitucarpin A are two new structurally related pterocarpans recently purified and characterized. Bitucarpin A differs from erybraedin C for the absence of a prenyl group in 5' position and the presence of a methoxylate hydroxyl group in 7, 4' positions. These compounds proved not to be clastogens in human lymphocytes per se but displayed anticlastogenic activity against mytomicin C and bleomycin C. Here we extended the study of their antiproliferative and apoptosis-inducing mechanism on human cell lines. Two human adenocarcinoma cell lines, LoVo and HT29, as examples of slow-growing solid tumors, proficient and deficient in mismatch repair system (MMR), p53 and Bcl-2, were used to evaluate the cytotoxicity of the drugs and their effects on the cell cycle, measured by flow cytometry. Erybraedin C similarly affects the survival of HT29 (MMR +/+, p53 -/- and Bcl-2 +/+) and LoVo (MMR -/-, p53 +/+ and Bcl-2 -/-) cells (LD(50): 1.94 and 1.73 microg/ml, respectively). By contrast, bitucarpin A exhibits a differential cytotoxicity in the cell lines (LD(50): 6.00 microg/ml, HT29, and 1.84 microg/ml, LoVo). The cell cycle distributions of the LoVo and HT29 cells treated with erybraedin C lacked a specific checkpoint arrest, whereas they underwent a characteristic sub-G(1) peak, time- and drug-concentration dependent. So that apoptotic process induced by erybraedin C in both adenocarcinoma cell lines is independent of cell cycle arrest and of phenotypic status of the cells as well. By contrast, bitucarpin A affects cell cycle progression on both cell lines, inducing a transient block in G(0)/G(1) along 24-96 h, and induces apoptosis with a cell density and treatment time dependency. Similar results were obtained with

  6. Novel MDM2 inhibitor SAR405838 (MI-773) induces p53-mediated apoptosis in neuroblastoma

    PubMed Central

    Lu, Jiaxiong; Guan, Shan; Zhao, Yanling; Yu, Yang; Wang, Yongfeng; Shi, Yonghua; Mao, Xinfang; Yang, Kristine L.; Sun, Wenjing; Xu, Xin; Yi, Joanna S.; Yang, Tianshu; Yang, Jianhua; Nuchtern, Jed G.

    2016-01-01

    Neuroblastoma (NB), which accounts for about 15% of cancer-related mortality in children, is the most common childhood extracranial malignant tumor. In NB, somatic mutations of the tumor suppressor, p53, are exceedingly rare. Unlike in adult tumors, the majority of p53 downstream functions are still intact in NB cells with wild-type p53. Thus, restoring p53 function by blocking its interaction with p53 suppressors such as MDM2 is a viable therapeutic strategy for NB treatment. Herein, we show that MDM2 inhibitor SAR405838 is a potent therapeutic drug for NB. SAR405838 caused significantly decreased cell viability of p53 wild-type NB cells and induced p53-mediated apoptosis, as well as augmenting the cytotoxic effects of doxorubicin (Dox). In an in vivo orthotopic NB mouse model, SAR405838 induced apoptosis in NB tumor cells. In summary, our data strongly suggest that MDM2-specific inhibitors like SAR405838 may serve not only as a stand-alone therapy, but also as an effective adjunct to current chemotherapeutic regimens for treating NB with an intact MDM2-p53 axis. PMID:27764791

  7. Reactivation of mutant p53 and induction of apoptosis in human tumor cells by maleimide analogs.

    PubMed

    Bykov, Vladimir J N; Issaeva, Natalia; Zache, Nicole; Shilov, Alexandre; Hultcrantz, Monica; Bergman, Jan; Selivanova, Galina; Wiman, Klas G

    2005-08-26

    Reactivation of mutant p53 is likely to provide important benefits for treatment of chemotherapy- and radiotherapy-resistant tumors. We demonstrate here that the maleimide-derived molecule MIRA-1 can reactivate DNA binding and preserve the active conformation of mutant p53 protein in vitro and restore transcriptional transactivation to mutant p53 in living cells. MIRA-1 induced mutant p53-dependent cell death in different human tumor cells carrying tetracycline-regulated mutant p53. The structural analog MIRA-3 showed antitumor activity in vivo against human mutant p53-carrying tumor xenografts in SCID mice. The MIRA scaffold is a novel lead for the development of anticancer drugs specifically targeting mutant p53.

  8. p18(Hamlet) mediates different p53-dependent responses to DNA-damage inducing agents.

    PubMed

    Lafarga, Vanesa; Cuadrado, Ana; Nebreda, Angel R

    2007-10-01

    Cells organize appropriate responses to environmental cues by activating specific signaling networks. Two proteins that play key roles in coordinating stress responses are the kinase p38alpha (MAPK14) and the transcription factor p53 (TP53). Depending on the nature and the extent of the stress-induced damage, cells may respond by arresting the cell cycle or by undergoing cell death, and these responses are usually associated with the phosphorylation of particular substrates by p38alpha as well as the activation of specific target genes by p53. We recently characterized a new p38alpha substrate, named p18(Hamlet) (ZNHIT1), which mediates p53-dependent responses to different genotoxic stresses. Thus, cisplatin or UV light induce stabilization of the p18(Hamlet) protein, which then enhances the ability of p53 to bind to and activate the promoters of pro-apoptotic genes such as NOXA and PUMA leading to apoptosis induction. In a similar way, we report here that p18(Hamlet) can also mediate the cell cycle arrest induced in response to gamma-irradiation, by participating in the p53-dependent upregulation of the cell cycle inhibitor p21(Cip1) (CDKN1A).

  9. Delayed expression of apoptosis in X-irradiated human leukemic MOLT-4 cells transfected with mutant p53.

    PubMed

    Nakano, Hisako; Yonekawa, Hiromichi; Shinohara, Kunio

    2003-06-01

    The effects of X-rays on cell survival, apoptosis, and long-term response in the development of cell death as measured by the dye exclusion test were studied in human leukemic MOLT-4 cells (p53 wild-type) stably transfected with a mutant p53 cDNA expression vector. Cell survival, as determined from colony-forming ability, was increased in an expression level dependent manner, but the increase was partial even with the highest-expressing clone (B3). This contrasts with the prior observation that cell death and apoptosis in B3 are completely inhibited at 24 h after irradiation with 1.8 Gy of X-rays. The examination of B3 cells incubated for longer than 24 h after X-irradiation showed a delay in the induction of cell death and apoptosis. Western blot analysis revealed that the time required to reach the highest level of wild-type p53 protein in B3 was longer than the time in MOLT-4 and that the p53 may be stabilized by the phosphorylation at Ser-15. These results suggest that the introduction of mutant p53 into MOLT-4 merely delays the development of apoptosis, during which the cells could repair the damage induced by X-rays, and results in the partial increase in cell survival.

  10. Thrombocytopenia induced by the histone deacetylase inhibitor abexinostat involves p53-dependent and -independent mechanisms

    PubMed Central

    Ali, A; Bluteau, O; Messaoudi, K; Palazzo, A; Boukour, S; Lordier, L; Lecluse, Y; Rameau, P; Kraus-Berthier, L; Jacquet-Bescond, A; Lelièvre, H; Depil, S; Dessen, P; Solary, E; Raslova, H; Vainchenker, W; Plo, I; Debili, N

    2013-01-01

    Abexinostat is a pan histone deacetylase inhibitor (HDACi) that demonstrates efficacy in malignancy treatment. Like other HDACi, this drug induces a profound thrombocytopenia whose mechanism is only partially understood. We have analyzed its effect at doses reached in patient plasma on in vitro megakaryopoiesis derived from human CD34+ cells. When added at day 0 in culture, abexinostat inhibited CFU-MK growth, megakaryocyte (MK) proliferation and differentiation. These effects required only a short incubation period. Decreased proliferation was due to induction of apoptosis and was not related to a defect in TPO/MPL/JAK2/STAT signaling. When added later (day 8), the compound induced a dose-dependent decrease (up to 10-fold) in proplatelet (PPT) formation. Gene profiling from MK revealed a silencing in the expression of DNA repair genes with a marked RAD51 decrease at protein level. DNA double-strand breaks were increased as attested by elevated γH2AX phosphorylation level. Moreover, ATM was phosphorylated leading to p53 stabilization and increased BAX and p21 expression. The use of a p53 shRNA rescued apoptosis, and only partially the defect in PPT formation. These results suggest that HDACi induces a thrombocytopenia by a p53-dependent mechanism along MK differentiation and a p53-dependent and -independent mechanism for PPT formation. PMID:23887629

  11. Anoikis triggers Mdm2-dependent p53 degradation

    PubMed Central

    Ghosh, Abhijit; Chen, Tina Chunyuan; Kapila, Yvonne L.

    2010-01-01

    The extracellular matrix (ECM) plays a key role in cell–cell communication and signaling, and the signals it propagates are important for tissue remodeling and survival. However, signals from disease-altered ECM may lead to anoikis—apoptotic cell death triggered by loss of ECM contacts. Previously, we found that an altered fibronectin matrix triggers anoikis in human primary ligament cells via a pathway that requires p53 transcriptional downregulation. Here we show that this p53 reduction is suppressed by transfecting cells with Mdm2 antisense oligonucleotides or small interfering RNA. Similar results were found in cells treated to prevent p53 and Mdm2 interactions. When p53 was overexpressed in cells lacking Mdm2 and p53, p53 levels were unaffected by anoikis conditions. However, cells cotransfected with p53 and wild type Mdm2, but not a mutant Mdm2, exhibited decreased p53 levels in response to anoikis conditions. Thus, cells under anoikis conditions undergo p53 degradation that is mediated by Mdm2. PMID:20577896

  12. Amphipathic silica nanoparticles induce cytotoxicity through oxidative stress mediated and p53 dependent apoptosis pathway in human liver cell line HL-7702 and rat liver cell line BRL-3A.

    PubMed

    Zuo, Daiying; Duan, Zhenfang; Jia, Yuanyuan; Chu, Tianxue; He, Qiong; Yuan, Juan; Dai, Wei; Li, Zengqiang; Xing, Liguo; Wu, Yingliang

    2016-09-01

    The aim of this study was to evaluate the potential cytotoxicity and the underlying mechanism of amphipathic silica nanoparticles (SiO2 NPs) exposure to human normal liver HL-7702 cells and rat normal liver BRL-3A cells. Prior to the cellular studies, transmission electron microscopy (TEM), dynamic light scattering (DLS), and X ray diffraction (XRD) were used to characterize SiO2 NPs, which proved the amorphous nature of SiO2 NPs with TEM diameter of 19.8±2.7nm. Further studies proved that exposure to SiO2 NPs dose-dependently induced cytotoxicity as revealed by cell counting kit (CCK-8) and lactate dehydrogenase (LDH) assays, with more severe cytotoxicity in HL-7702 cells than BRL-3A cells. Reactive oxygen species (ROS) and glutathione (GSH) assays showed elevated oxidative stress in both cells. Morphological studies by microscopic observation, Hochest 33258 and AO/EB staining indicated significant apoptotic changes after the cells being exposed to SiO2 NPs. Further studies by western blot indicated that SiO2 NPs exposure to both cells up-regulated p53, Bax and cleaved caspase-3 expression and down-regulated Bcl-2 and caspase-3 levels. Activated caspase-3 activity detected by colorimetric assay kit and caspase-3/7 activity detected by fluorescent real-time detection kit were significantly increased by SiO2 NPs exposure. In addition, antioxidant vitamin C significantly attenuated SiO2 NPs-induced caspase-3 activation, which indicated that SiO2 NPs-induced oxidative stress was involved in the process of HL-7702 and BRL-3A cell apoptosis. Taken together, these results suggested that SiO2 NPs-induced cytotoxicity in HL-7702 and BRL-3A cells was through oxidative stress mediated and p53, caspase-3 and Bax/Bcl-2 dependent pathway and HL-7702 cells were more sensitive to SiO2 NPs-induced cytotoxicity than BRL-3A cells.

  13. P53-dependent upregulation of neutral sphingomyelinase-2: role in doxorubicin-induced growth arrest

    PubMed Central

    Shamseddine, A A; Clarke, C J; Carroll, B; Airola, M V; Mohammed, S; Rella, A; Obeid, L M; Hannun, Y A

    2015-01-01

    Neutral sphingomyelinase-2 (nSMase2) is a ceramide-generating enzyme that has been implicated in growth arrest, apoptosis and exosome secretion. Although previous studies have reported transcriptional upregulation of nSMase2 in response to daunorubicin, through Sp1 and Sp3 transcription factors, the role of the DNA damage pathway in regulating nSMase2 remains unclear. In this study, we show that doxorubicin induces a dose-dependent induction of nSMase2 mRNA and protein with concomitant increases in nSMase activity and ceramide levels. Upregulation of nSMase2 was dependent on ATR, Chk1 and p53, thus placing it downstream of the DNA damage pathway. Moreover, overexpression of p53 was sufficient to transcriptionally induce nSMase2, without the need for DNA damage. DNA-binding mutants as well as acetylation mutants of p53 were unable to induce nSMase2, suggesting a role of nSMase2 in growth arrest. Moreover, knockdown of nSMase2 prevented doxorubicin-induced growth arrest. Finally, p53-induced nSMase2 upregulation appears to occur via a novel transcription start site upstream of exon 3. These results identify nSMase2 as a novel p53 target gene, regulated by the DNA damage pathway to induce cell growth arrest. PMID:26512957

  14. Role of p53 in cdk Inhibitor VMY-1-103-induced Apoptosis in Prostate Cancer

    DTIC Science & Technology

    2013-11-01

    JA, Uren A. Arsenic trioxide inhibits human cancer cell growth and tumor development in mice by blocking Hedgehog /GLI pathway. J Clin Invest. 2011...induced apoptosis in prostate cancer PRINCIPAL INVESTIGATOR: Lymor Ringer...2013 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Role of p53 in cdk inhibitor VMY-1-103-induced apoptosis in prostate cancer 5b. GRANT NUMBER

  15. The role of the p53 protein in nitrosative stress-induced apoptosis of PC12 rat pheochromocytoma cells.

    PubMed

    Varga, Judit; Bátor, Judit; Péter, Márton; Árvai, Zita; Pap, Marianna; Sétáló, György; Szeberényi, József

    2014-10-01

    PC12 rat pheochromocytoma cells are widely used to investigate signaling pathways. The p143p53PC12 cell line expresses a Val143Ala mutant p53 protein that is less capable of binding to the p53 consensus site in DNA than its wild-type counterpart. Nitric oxide (NO), depending on its concentration, is able to activate several signal transduction pathways. We used sodium nitroprusside (SNP), an NO donor compound, to analyze NO-induced cellular stress in order to clarify the mechanism and role of nitrosative stress in pathological processes, including inflammation and cancer. SNP caused cell death when applied at a concentration of 400 μM, p143p53PC12 cells showing higher sensitivity than wild-type PC12 cells. The mechanisms leading to the increased SNP-sensitivity of p143p53PC12 cells were then investigated. The 400-μM SNP treatment caused stress kinase activation, phosphorylation of the eukaryotic initiation factor eIF2α and p53 protein, proteolytic activation of protein kinase R, caspase-9, and caspase-3, p53 stabilization, CHOP induction, cytochrome c release from mitochondria, and a decline in the level of the Bcl-2 protein in both cell lines. All these SNP-induced changes were more robust and/or permanent in cells with the mutant p53 protein. We thus conclude that (1) the main cause of the SNP-induced apoptosis of PC12 cells is the repression of the bcl-2 gene, evoked through p53 stabilization, stress kinase activation, and CHOP induction; (2) the higher SNP sensitivity of p143p53PC12 cells is the consequence of the stronger and earlier activation of the intrinsic apoptotic pathway.

  16. {sub p}53-Dependent Adaptive Responses in Human Cells Exposed to Space Radiations

    SciTech Connect

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

    2010-11-15

    Purpose: It has been reported that priming irradiation or conditioning irradiation with a low dose of X-rays in the range of 0.02-0.1 Gy induces a p53-dependent adaptive response in mammalian cells. The aim of the present study was to clarify the effect of space radiations on the adaptive response. Methods and Materials: Two human lymphoblastoid cell lines were used; one cell line bears a wild-type p53 (wtp53) gene, and another cell line bears a mutated p53 (mp53) gene. The cells were frozen during transportation on the space shuttle and while in orbit in the International Space Station freezer for 133 days between November 15, 2008 and March 29, 2009. After the frozen samples were returned to Earth, the cells were cultured for 6 h and then exposed to a challenging X-ray-irradiation (2 Gy). Cellular sensitivity, apoptosis, and chromosome aberrations were scored using dye-exclusion assays, Hoechst33342 staining assays, and chromosomal banding techniques, respectively. Results: In cells exposed to space radiations, adaptive responses such as the induction of radioresistance and the depression of radiation-induced apoptosis and chromosome aberrations were observed in wtp53 cells but not in mp53 cells. Conclusion: These results have confirmed the hypothesis that p53-dependent adaptive responses are apparently induced by space radiations within a specific range of low doses. The cells exhibited this effect owing to space radiations exposure, even though the doses in space were very low.

  17. Non-dioxin-like PCBs interact with benzo[a]pyrene-induced p53-responses and inhibit apoptosis

    SciTech Connect

    Al-Anati, Lauy Hoegberg, Johan; Stenius, Ulla

    2010-12-01

    Non-dioxin-like polychlorinated biphenyls (NDL-PCBs) and polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants often co-existing in contaminated environments. However, there are few studies on the effects of co-exposure, in particular on effects of pure NDL-PCB congeners and PAHs. We have evaluated the effects of some highly purified NDL-PCBs and benzo[a]pyrene (BP) on BP-induced Raf, Erk, Mdm2, p53 signaling and on BP-induced apoptosis and cell cycle arrest. PCBs (1 {mu}M) were added to HepG2 cells 1 h prior to BP and the incubation was stopped at 24 h. Employing Western blotting we found that NDL-PCBs (28, 101 and 153) amplified the BP-induced inactivating phosphorylation of Raf (pRaf Ser 259) and decreased levels of pErk Tyr 204. This treatment also resulted in the attenuation of BP-induced Mdm2 phosphorylation at Ser166 and amplification of the p53 Ser15 response. These effects were associated with an unexpected inhibition of BP-induced apoptosis. A dioxin-like PCB (DL-PCB 126) was used as reference and gave results that were predictable from previous studies, i.e. it attenuated BP-induced p53 response and apoptosis. In an effort to explain why the NDL-PCB-induced amplification of the p53 response was associated with a decreased apoptotic response we analyzed FoxO3a, which may translocate p53 to the cytoplasm. We found that NDL-PCBs reduced the level of phosphorylated FoxO3a at Thr32. This phosphorylation promotes a cytoplasmic translocation of FoxO3a and p53 and our data suggest that NDL-PCBs may inhibit BP-induced apoptosis by preventing a FoxO3a-dependent translocation of p53 to the cytoplasm.

  18. Active Akt and Functional p53 Modulate Apoptosis in Abelson Virus-Transformed Pre-B Cells

    PubMed Central

    Gong, Li; Unnikrishnan, Indira; Raghavan, Anuradha; Parmar, Kalindi; Rosenberg, Naomi

    2004-01-01

    Suppression of apoptosis is an important feature of the Abelson murine leukemia virus (Ab-MLV) transformation process. During multistep transformation, Ab-MLV-infected pre-B cells undergo p53-dependent apoptosis during the crisis phase of transformation. Even once cells are fully transformed, an active v-Abl protein tyrosine kinase is required to suppress apoptosis because cells transformed by temperature-sensitive (ts) kinase mutants undergo rapid apoptosis after a shift to the nonpermissive temperature. However, inactivation of the v-Abl protein by a temperature shift interrupts signals transmitted via multiple pathways, making it difficult to identify those that are critically important for the suppression of apoptosis. To begin to dissect these pathways, we tested the ability of an SH2 domain Ab-MLV mutant, P120/R273K, to rescue aspects of the ts phenotype of pre-B cells transformed by the conditional kinase domain mutant. The P120/R273K mutant suppressed apoptosis at the nonpermissive temperature, a phenotype correlated with its ability to activate Akt. Apoptosis also was suppressed at the nonpermissive temperature by constitutively active Akt and in p53-null pre-B cells transformed with the ts kinase domain mutant. These data indicate that an intact Src homology 2 (SH2) domain is not critical for apoptosis suppression and suggest that signals transmitted through Akt and p53 play an important role in the response. PMID:14747529

  19. 3-MCPD 1-Palmitate Induced Tubular Cell Apoptosis In Vivo via JNK/p53 Pathways.

    PubMed

    Liu, Man; Huang, Guoren; Wang, Thomas T Y; Sun, Xiangjun; Yu, Liangli Lucy

    2016-05-01

    Fatty acid esters of 3-chloro-1, 2-propanediol (3-MCPD esters) are a group of processing induced food contaminants with nephrotoxicity but the molecular mechanism(s) remains unclear. This study investigated whether and how the JNK/p53 pathway may play a role in the nephrotoxic effect of 3-MCPD esters using 3-MCPD 1-palmitate (MPE) as a probe compound in Sprague Dawley rats. Microarray analysis of the kidney from the Sprague Dawley rats treated with MPE, using Gene Ontology categories and KEGG pathways, revealed that MPE altered mRNA expressions of the genes involved in the mitogen-activated protein kinase (JNK and ERK), p53, and apoptotic signal transduction pathways. The changes in the mRNA expressions were confirmed by qRT-PCR and Western blot analyses and were consistent with the induction of tubular cell apoptosis as determined by histopathological, TUNEL, and immunohistochemistry analyses in the kidneys of the Sprague Dawley rats. Additionally, p53 knockout attenuated the apoptosis, and the apoptosis-related protein bax expression and cleaved caspase-3 activation induced by MPE in the p53 knockout C57BL/6 mice, whereas JNK inhibitor SP600125 but not ERK inhibitor U0126 inhibited MPE-induced apoptosis, supporting the conclusion that JNK/p53 might play a critical role in the tubular cell apoptosis induced by MPE and other 3-MCPD fatty acid esters.

  20. Ligand dependent restoration of human TLR3 signaling and death in p53 mutant cells

    PubMed Central

    Menendez, Daniel; Lowe, Julie M.; Snipe, Joyce; Resnick, Michael A.

    2016-01-01

    Diversity within the p53 transcriptional network can arise from a matrix of changes that include target response element sequences and p53 expression level variations. We previously found that wild type p53 (WT p53) can regulate expression of most innate immune-related Toll-like-receptor genes (TLRs) in human cells, thereby affecting immune responses. Since many tumor-associated p53 mutants exhibit change-of-spectrum transactivation from various p53 targets, we examined the ability of twenty-five p53 mutants to activate endogenous expression of the TLR gene family in p53 null human cancer cell lines following transfection with p53 mutant expression vectors. While many mutants retained the ability to drive TLR expression at WT levels, others exhibited null, limited, or change-of-spectrum transactivation of TLR genes. Using TLR3 signaling as a model, we show that some cancer-associated p53 mutants amplify cytokine, chemokine and apoptotic responses after stimulation by the cognate ligand poly(I:C). Furthermore, restoration of WT p53 activity for loss-of-function p53 mutants by the p53 reactivating drug RITA restored p53 regulation of TLR3 gene expression and enhanced DNA damage-induced apoptosis via TLR3 signaling. Overall, our findings have many implications for understanding the impact of WT and mutant p53 in immunological responses and cancer therapy. PMID:27533082

  1. HIF-1 antagonizes p53-mediated apoptosis through a secreted neuronal tyrosinase.

    PubMed

    Sendoel, Ataman; Kohler, Ines; Fellmann, Christof; Lowe, Scott W; Hengartner, Michael O

    2010-06-03

    Hypoxia-inducible factor (HIF) is a transcription factor that regulates fundamental cellular processes in response to changes in oxygen concentration. HIFalpha protein levels are increased in most solid tumours and correlate with patient prognosis. The link between HIF and apoptosis, a major determinant of cancer progression and treatment outcome, is poorly understood. Here we show that Caenorhabditis elegans HIF-1 protects against DNA-damage-induced germ cell apoptosis by antagonizing the function of CEP-1, the homologue of the tumour suppressor p53. The antiapoptotic property of HIF-1 is mediated by means of transcriptional upregulation of the tyrosinase family member TYR-2 in the ASJ sensory neurons. TYR-2 is secreted by ASJ sensory neurons to antagonize CEP-1-dependent germline apoptosis. Knock down of the TYR-2 homologue TRP2 (also called DCT) in human melanoma cells similarly increases apoptosis, indicating an evolutionarily conserved function. Our findings identify a novel link between hypoxia and programmed cell death, and provide a paradigm for HIF-1 dictating apoptotic cell fate at a distance.

  2. HIF-1 antagonizes p53-mediated apoptosis through a secreted neuronal tyrosinase

    PubMed Central

    Sendoel, Ataman; Kohler, Ines; Fellmann, Christof; Lowe, Scott W.; Hengartner, Michael O.

    2012-01-01

    Hypoxia-inducible factor (HIF) is a transcription factor that regulates fundamental cellular processes in response to changes in oxygen concentration. HIFα protein levels are increased in most solid tumours and correlate with patient prognosis. The link between HIF and apoptosis, a major determinant of cancer progression and treatment outcome, is poorly understood. Here we show that Caenorhabditis elegans HIF-1 protects against DNA-damage-induced germ cell apoptosis by antagonizing the function of CEP-1, the homologue of the tumour suppressor p53. The antiapoptotic property of HIF-1 is mediated by means of transcriptional upregulation of the tyrosinase family member TYR-2 in the ASJ sensory neurons. TYR-2 is secreted by ASJ sensory neurons to antagonize CEP-1-dependent germline apoptosis. Knock down of the TYR-2 homologue TRP2 (also called DCT) in human melanoma cells similarly increases apoptosis, indicating an evolutionarily conserved function. Our findings identify a novel link between hypoxia and programmed cell death, and provide a paradigm for HIF-1 dictating apoptotic cell fate at a distance. PMID:20520707

  3. p53 Mediates Colistin-Induced Autophagy and Apoptosis in PC-12 Cells.

    PubMed

    Zhang, Ling; Xie, Daoyuan; Chen, Xueping; Hughes, Maria L R; Jiang, Guozheng; Lu, Ziyin; Xia, Chunli; Li, Li; Wang, Jinli; Xu, Wei; Sun, Yuan; Li, Rui; Wang, Rui; Qian, Feng; Li, Jian; Li, Jichang

    2016-09-01

    The mechanism of colistin-induced neurotoxicity is still unknown. Our recent study (L. Zhang, Y. H. Zhao, W. J. Ding, G. Z. Jiang, Z. Y. Lu, L. Li, J. L. Wang, J. Li, and J. C. Li, Antimicrob Agents Chemother 59:2189-2197, 2015, http://dx.doi.org/10.1128/AAC.04092-14; H. Jiang, J. C. Li, T. Zhou, C. H. Wang, H. Zhang, and H. Wang, Int J Mol Med 33:1298-1304, 2014, http://dx.doi.org/10.3892/ijmm.2014.1684) indicates that colistin induces autophagy and apoptosis in rat adrenal medulla PC-12 cells, and there is interplay between both cellular events. As an important cellular stress sensor, phosphoprotein p53 can trigger cell cycle arrest and apoptosis and regulate autophagy. The aim of the present study was to investigate the involvement of the p53 pathway in colistin-induced neurotoxicity in PC-12 cells. Specifically, cells were treated with colistin (125 μg/ml) in the absence and presence of a p53 inhibitor, pifithrin-α (PFT-α; 20 nM), for 12 h and 24 h, and the typical hallmarks of autophagy and apoptosis were examined by fluorescence/immunofluorescence microscopy and electron microscopy, real-time PCR, and Western blotting. The results indicate that colistin had a stimulatory effect on the expression levels of the target genes and proteins involved in autophagy and apoptosis, including LC3-II/I, p53, DRAM (damage-regulated autophagy modulator), PUMA (p53 upregulated modulator of apoptosis), Bax, p-AMPK (activated form of AMP-activated protein kinase), and caspase-3. In contrast, colistin appeared to have an inhibitory effect on the expression of p-mTOR (activated form of mammalian target of rapamycin), which is another target protein in autophagy. Importantly, analysis of the levels of p53 in the cells treated with colistin revealed an increase in nuclear p53 at 12 h and cytoplasmic p53 at 24 h. Pretreatment of colistin-treated cells with PFT-α inhibited autophagy and promoted colistin-induced apoptosis. This is the first study to demonstrate that colistin

  4. p53 Mediates Colistin-Induced Autophagy and Apoptosis in PC-12 Cells

    PubMed Central

    Zhang, Ling; Xie, Daoyuan; Chen, Xueping; Hughes, Maria L. R.; Jiang, Guozheng; Lu, Ziyin; Xia, Chunli; Li, Li; Wang, Jinli; Xu, Wei; Sun, Yuan; Li, Rui; Wang, Rui; Qian, Feng

    2016-01-01

    The mechanism of colistin-induced neurotoxicity is still unknown. Our recent study (L. Zhang, Y. H. Zhao, W. J. Ding, G. Z. Jiang, Z. Y. Lu, L. Li, J. L. Wang, J. Li, and J. C. Li, Antimicrob Agents Chemother 59:2189–2197, 2015, http://dx.doi.org/10.1128/AAC.04092-14; H. Jiang, J. C. Li, T. Zhou, C. H. Wang, H. Zhang, and H. Wang, Int J Mol Med 33:1298–1304, 2014, http://dx.doi.org/10.3892/ijmm.2014.1684) indicates that colistin induces autophagy and apoptosis in rat adrenal medulla PC-12 cells, and there is interplay between both cellular events. As an important cellular stress sensor, phosphoprotein p53 can trigger cell cycle arrest and apoptosis and regulate autophagy. The aim of the present study was to investigate the involvement of the p53 pathway in colistin-induced neurotoxicity in PC-12 cells. Specifically, cells were treated with colistin (125 μg/ml) in the absence and presence of a p53 inhibitor, pifithrin-α (PFT-α; 20 nM), for 12 h and 24 h, and the typical hallmarks of autophagy and apoptosis were examined by fluorescence/immunofluorescence microscopy and electron microscopy, real-time PCR, and Western blotting. The results indicate that colistin had a stimulatory effect on the expression levels of the target genes and proteins involved in autophagy and apoptosis, including LC3-II/I, p53, DRAM (damage-regulated autophagy modulator), PUMA (p53 upregulated modulator of apoptosis), Bax, p-AMPK (activated form of AMP-activated protein kinase), and caspase-3. In contrast, colistin appeared to have an inhibitory effect on the expression of p-mTOR (activated form of mammalian target of rapamycin), which is another target protein in autophagy. Importantly, analysis of the levels of p53 in the cells treated with colistin revealed an increase in nuclear p53 at 12 h and cytoplasmic p53 at 24 h. Pretreatment of colistin-treated cells with PFT-α inhibited autophagy and promoted colistin-induced apoptosis. This is the first study to demonstrate that colistin

  5. Lonidamine induces apoptosis in drug-resistant cells independently of the p53 gene.

    PubMed Central

    Del Bufalo, D; Biroccio, A; Soddu, S; Laudonio, N; D'Angelo, C; Sacchi, A; Zupi, G

    1996-01-01

    Lonidamine, a dichlorinated derivative of indazole-3-carboxylic acid, was shown to play a significant role in reversing or overcoming multidrug resistance. Here, we show that exposure to 50 microg/ml of lonidamine induces apoptosis in adriamycin and nitrosourea-resistant cells (MCF-7 ADR(r) human breast cancer cell line, and LB9 glioblastoma multiform cell line), as demonstrated by sub-G1 peaks in DNA content histograms, condensation of nuclear chromatin, and internucleosomal DNA fragmentation. Moreover, we find that apoptosis is preceded by accumulation of the cells in the G0/G1 phase of the cell cycle. Interestingly, lonidamine fails to activate the apoptotic program in the corresponding sensitive parental cell lines (ADR-sensitive MCF-7 WT, and nitrosourea-sensitive LI cells) even after long exposure times. The evaluation of bcl-2 protein expression suggests that this different effect of lonidamine treatment in drug-resistant and -sensitive cell lines might not simply be due to dissimilar expression levels of bcl-2 protein. To determine whether the lonidamine-induced apoptosis is mediated by p53 protein, we used cells lacking endogenous p53 and overexpressing either wild-type p53 or dominant-negative p53 mutant. We find that apoptosis by lonidamine is independent of the p53 gene. PMID:8787680

  6. The Chemopreventive Effects of Protandim: Modulation of p53 Mitochondrial Translocation and Apoptosis during Skin Carcinogenesis

    PubMed Central

    Robbins, Delira; Gu, Xin; Shi, Runhua; Liu, Jianfeng; Wang, Fei; Ponville, Jacqulyne; McCord, Joe M.; Zhao, Yunfeng

    2010-01-01

    Protandim, a well defined dietary combination of 5 well-established medicinal plants, is known to induce endogenous antioxidant enzymes, such as manganese superoxide dismutase (MnSOD). Our previous studies have shown through the induction of various antioxidant enzymes, products of oxidative damage can be decreased. In addition, we have shown that tumor multiplicity and incidence can be decreased through the dietary administration of Protandim in the two-stage skin carcinogenesis mouse model. It has been demonstrated that cell proliferation is accommodated by cell death during DMBA/TPA treatment in the two-stage skin carcinogenesis model. Therefore, we investigated the effects of the Protandim diet on apoptosis; and proposed a novel mechanism of chemoprevention utilized by the Protandim dietary combination. Interestingly, Protandim suppressed DMBA/TPA induced cutaneous apoptosis. Recently, more attention has been focused on transcription-independent mechanisms of the tumor suppressor, p53, that mediate apoptosis. It is known that cytoplasmic p53 rapidly translocates to the mitochondria in response to pro-apoptotic stress. Our results showed that Protandim suppressed the mitochondrial translocation of p53 and mitochondrial outer membrane proteins such as Bax. We examined the levels of p53 and MnSOD expression/activity in murine skin JB6 promotion sensitive (P+) and promotion-resistant (P-) epidermal cells. Interestingly, p53 was induced only in P+ cells, not P- cells; whereas MnSOD is highly expressed in P- cells when compared to P+ cells. In addition, wild-type p53 was transfected into JB6 P- cells. We found that the introduction of wild-type p53 promoted transformation in JB6 P- cells. Our results suggest that suppression of p53 and induction of MnSOD may play an important role in the tumor suppressive activity of Protandim. PMID:20689586

  7. The chemopreventive effects of Protandim: modulation of p53 mitochondrial translocation and apoptosis during skin carcinogenesis.

    PubMed

    Robbins, Delira; Gu, Xin; Shi, Runhua; Liu, Jianfeng; Wang, Fei; Ponville, Jacqulyne; McCord, Joe M; Zhao, Yunfeng

    2010-07-30

    Protandim, a well defined dietary combination of 5 well-established medicinal plants, is known to induce endogenous antioxidant enzymes, such as manganese superoxide dismutase (MnSOD). Our previous studies have shown through the induction of various antioxidant enzymes, products of oxidative damage can be decreased. In addition, we have shown that tumor multiplicity and incidence can be decreased through the dietary administration of Protandim in the two-stage skin carcinogenesis mouse model. It has been demonstrated that cell proliferation is accommodated by cell death during DMBA/TPA treatment in the two-stage skin carcinogenesis model. Therefore, we investigated the effects of the Protandim diet on apoptosis; and proposed a novel mechanism of chemoprevention utilized by the Protandim dietary combination. Interestingly, Protandim suppressed DMBA/TPA induced cutaneous apoptosis. Recently, more attention has been focused on transcription-independent mechanisms of the tumor suppressor, p53, that mediate apoptosis. It is known that cytoplasmic p53 rapidly translocates to the mitochondria in response to pro-apoptotic stress. Our results showed that Protandim suppressed the mitochondrial translocation of p53 and mitochondrial outer membrane proteins such as Bax. We examined the levels of p53 and MnSOD expression/activity in murine skin JB6 promotion sensitive (P+) and promotion-resistant (P-) epidermal cells. Interestingly, p53 was induced only in P+ cells, not P- cells; whereas MnSOD is highly expressed in P- cells when compared to P+ cells. In addition, wild-type p53 was transfected into JB6 P- cells. We found that the introduction of wild-type p53 promoted transformation in JB6 P- cells. Our results suggest that suppression of p53 and induction of MnSOD may play an important role in the tumor suppressive activity of Protandim.

  8. TGEV nucleocapsid protein induces cell cycle arrest and apoptosis through activation of p53 signaling

    SciTech Connect

    Ding, Li; Huang, Yong; Du, Qian; Dong, Feng; Zhao, Xiaomin; Zhang, Wenlong; Xu, Xingang; Tong, Dewen

    2014-03-07

    Highlights: • TGEV N protein reduces cell viability by inducing cell cycle arrest and apoptosis. • TGEV N protein induces cell cycle arrest and apoptosis by regulating p53 signaling. • TGEV N protein plays important roles in TGEV-induced cell cycle arrest and apoptosis. - Abstract: Our previous studies showed that TGEV infection could induce cell cycle arrest and apoptosis via activation of p53 signaling in cultured host cells. However, it is unclear which viral gene causes these effects. In this study, we investigated the effects of TGEV nucleocapsid (N) protein on PK-15 cells. We found that TGEV N protein suppressed cell proliferation by causing cell cycle arrest at the S and G2/M phases and apoptosis. Characterization of various cellular proteins that are involved in regulating cell cycle progression demonstrated that the expression of N gene resulted in an accumulation of p53 and p21, which suppressed cyclin B1, cdc2 and cdk2 expression. Moreover, the expression of TGEV N gene promoted translocation of Bax to mitochondria, which in turn caused the release of cytochrome c, followed by activation of caspase-3, resulting in cell apoptosis in the transfected PK-15 cells following cell cycle arrest. Further studies showed that p53 inhibitor attenuated TGEV N protein induced cell cycle arrest at S and G2/M phases and apoptosis through reversing the expression changes of cdc2, cdk2 and cyclin B1 and the translocation changes of Bax and cytochrome c induced by TGEV N protein. Taken together, these results demonstrated that TGEV N protein might play an important role in TGEV infection-induced p53 activation and cell cycle arrest at the S and G2/M phases and apoptosis occurrence.

  9. MDM4 (MDMX) overexpression enhances stabilization of stress-induced p53 and promotes apoptosis.

    PubMed

    Mancini, Francesca; Gentiletti, Francesca; D'Angelo, Marco; Giglio, Simona; Nanni, Simona; D'Angelo, Carmen; Farsetti, Antonella; Citro, Gennaro; Sacchi, Ada; Pontecorvi, Alfredo; Moretti, Fabiola

    2004-02-27

    Rescue of embryonic lethality in MDM4(-/-) mice through concomitant loss of p53 has revealed a functional partnership between the two proteins. Biochemical studies have suggested that MDM4 may act as a negative regulator of p53 levels and activity. On the other hand, MDM4 overexpression has been reported to stabilize p53 levels and to counteract MDM2-degradative activity. We have investigated the functional role of MDM4 overexpression on cell behavior. In both established and primary cells cultured under stress conditions, overexpression of MDM4 significantly increased p53-dependent cell death, in correlation with enhanced induction of the endogenous p53 protein levels. This phenomenon was associated with induced p53 transcriptional activity and increased levels of the proapoptotic protein, Bax. Further, p53 stabilization was accompanied by decreased association of the protein to its negative regulator, MDM2. These findings reveal a novel role for MDM4 by demonstrating that in non-tumor cells under stress conditions it may act as a positive regulator of p53 activity, mainly by controlling p53 levels. They also indicate a major distinction between the biological consequences of MDM4 and MDM2 overexpression.

  10. Glycyrrhizic acid attenuates CCl4-induced hepatocyte apoptosis in rats via a p53-mediated pathway

    PubMed Central

    Guo, Xiao-Ling; Liang, Bo; Wang, Xue-Wei; Fan, Fu-Gang; Jin, Jing; Lan, Rui; Yang, Jing-Hui; Wang, Xiao-Chun; Jin, Lei; Cao, Qin

    2013-01-01

    AIM: To investigate the effect of glycyrrhizic acid (GA) on carbon tetrachloride (CCl4)-induced hepatocyte apoptosis in rats via a p53-dependent mitochondrial pathway. METHODS: Forty-five male Sprague-Dawley rats were randomly and equally divided into three groups, the control group, the CCl4 group, and the GA treatment group. To induce liver fibrosis in this model, rats were given a subcutaneous injection of a 40% solution of CCl4 in olive oil at a dose of 0.3 mL/100 g body weight biweekly for 8 wk, while controls received the same isovolumetric dose of olive oil by hypodermic injection, with an initial double-dose injection. In the GA group, rats were also treated with a 40% solution of CCl4 plus 0.2% GA solution in double distilled water by the intraperitoneal injection of 3 mL per rat three times a week from the first week following previously published methods, with modifications. Controls were given the same isovolumetric dose of double distilled water. Liver function parameters, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined. Pathologic changes in the liver were detected by hematoxylin and eosin staining. Collagen fibers were evaluated by Sirius red staining. Hepatocyte apoptosis was investigated using the terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick end labeling (TUNEL) assay and the cleaved caspase-3 immunohistochemistry assay. The expression levels of p53 and apoptosis-related proteins were evaluated by immunohistochemistry or Western blotting analysis. RESULTS: After 8 wk of treatment, GA significantly reduced serum activity of ALT (from 526.7 ± 57.2 to 342 ± 44.8, P < 0.05) and AST (from 640 ± 33.7 to 462.8 ± 30.6, P < 0.05), attenuated the changes in liver histopathology and reduced the staging score (from 3.53 ± 0.74 to 3.00 ± 0.76, P < 0.05) in CCl4-treated rats. GA markedly reduced the positive area of Sirius red and the ratio of the hepatic fibrotic region (from 7

  11. Structured DNA promotes phosphorylation of p53 by DNA-dependent protein kinase at serine 9 and threonine 18.

    PubMed

    Soubeyrand, Sébastien; Schild-Poulter, Caroline; Haché, Robert J G

    2004-09-01

    Phosphorylation at multiple sites within the N-terminus of p53 promotes its dissociation from hdm2/mdm2 and stimulates its transcriptional regulatory potential. The large phosphoinositide 3-kinase-like kinases ataxia telangiectasia mutated gene product and the ataxia telangectasia and RAD-3-related kinase promote phosphorylation of human p53 at Ser15 and Ser20, and are required for the activation of p53 following DNA damage. DNA-dependent protein kinase (DNA-PK) is another large phosphoinositide 3-kinase-like kinase with the potential to phosphorylate p53 at Ser15, and has been proposed to enhance phosphorylation of these sites in vivo. Moreover, recent studies support a role for DNA-PK in the regulation of p53-mediated apoptosis. We have shown previously that colocalization of p53 and DNA-PK to structured single-stranded DNA dramatically enhances the potential for p53 phosphorylation by DNA-PK. We report here the identification of p53 phosphorylation at two novel sites for DNA-PK, Thr18 and Ser9. Colocalization of p53 and DNA-PK on structured DNA was required for efficient phosphorylation of p53 at multiple sites, while specific recognition of Ser9 and Thr18 appeared to be dependent upon additional determinants of p53 beyond the N-terminal 65 amino acids. Our results suggest a role for DNA-PK in the modulation of p53 activity resultant from the convergence of p53 and DNA-PK on structured DNA.

  12. Cholecystokinin attenuates radiation-induced lung cancer cell apoptosis by modulating p53 gene transcription

    PubMed Central

    Han, Yi; Su, Chongyu; Yu, Daping; Zhou, Shijie; Song, Xiaoyun; Liu, Shuku; Qin, Ming; Li, Yunsong; Xiao, Ning; Cao, Xiaoqing; Shi, Kang; Cheng, Xu; Liu, Zhidong

    2017-01-01

    The deregulation of p53 in cancer cells is one of the important factors by which cancer cells escape from the immune surveillance. Cholecystokinin (CCK) has strong bioactivity in the regulation of a number of cell activities. This study tests a hypothesis that CCK interferes with p53 expression to affect the apoptotic process in lung cancer (tumor) cells. In this study, tumor-bearing mice and A549 cells (a tumor cell line) were irradiated. The expression of CCK and p53 in tumor cells was assessed with RT-qPCR and Western blotting. The binding of p300 to the promoter of p53 was evaluated by chromatin immunoprecipitation. We observed that, with a given amount and within a given period, small doses/more sessions of irradiation markedly increased the levels of CCK in the sera and tumor cells, which were positively correlated with the tumor growth in mice and negatively correlated with tumor cell apoptosis. CCK increased the levels of histone acetyltransferase p300 and repressed the levels of nuclear factor-kB at the p53 promoter locus in tumor cells, which suppressed the expression of p53. In conclusion, CCK plays an important role in attenuating the radiation-induced lung cancer cell apoptosis. CCK may be a novel therapeutic target in the treatment of lung cancers. PMID:28337291

  13. NDRG4 is a novel oncogenic protein and p53 associated regulator of apoptosis in malignant meningioma cells

    PubMed Central

    Kotipatruni, Rama P.; Ren, Xuan; Thotala, Dinesh; Jaboin, Jerry J.

    2015-01-01

    Aggressive meningiomas exhibit high levels of recurrence, morbidity and mortality. When surgical and radiation options are exhausted, there is need for novel molecularly-targeted therapies. We have recently identified NDRG4 overexpression in aggressive meningiomas. NDRG4 is a member of the N-Myc Downstream Regulated Gene (NDRG) family of the alpha/beta hydrolase superfamily. We have demonstrated that NDRG4 downregulation results in decreased cell proliferation, migration and invasion. In follow up to our prior studies; here we demonstrate that the predominant form of cell death following NDRG4 silencing is apoptosis, utilizing Annexin-V flow cytometry assay. We show that apoptosis caused by p53 upregulation, phosphorylation at Ser15, BAX activation, Bcl-2 and BcL-xL downregulation, mitochondrial cytochrome c release and execution of caspases following NDRG4 depletion. Sub-cellular distribution of BAX and cytochrome c indicated mitochondrial-mediated apoptosis. In addition, we carried out the fluorescence cytochemical analysis to confirm mitochondrial-mediated apoptosis by changes in mitochondrial membrane potential (Ψm), using JC-1 dye. Immunoprecipitation and immunofluorescence confirmed binding of NDRG4 to p53. In addition, we demonstrate that apoptosis is mitochondrial and p53 dependent. The proapoptotic effect of p53 was verified by the results in which a small molecule compound PFT-α, an inhibitor of p53 phosphorylation, is greatly protected against targeting NDRG4 induced apoptosis. These findings bring novel insight to the roles of NDRG4 in meningioma progression. A better understanding of this pathway and its role in meningioma carcinogenesis and cell biology is promising for the development of novel therapeutic targets for the management of aggressive meningiomas. PMID:26053091

  14. Che-1 gene silencing induces osteosarcoma cell apoptosis by inhibiting mutant p53 expression

    SciTech Connect

    Liu, Ming; Wang, Dan 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 chromatin 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.

  15. P53/Drp1-dependent mitochondrial fission mediates aldosterone-induced podocyte injury and mitochondrial dysfunction.

    PubMed

    Yuan, Yanggang; Zhang, Aiqing; Qi, Jia; Wang, Hui; Liu, Xi; Zhao, Min; Duan, Suyan; Huang, Zhimin; Zhang, Chengning; Wu, Lin; Zhang, Bo; Zhang, Aihua; Xing, Changying

    2017-06-28

    Mitochondrial dysfunction is increasingly recognized as an important factor in glomerular diseases. Previous study showed that mitochondrial fission contributed mitochondrial dysfunction. However, the mechanism of mitochondrial fission on mitochondrial dysfunction in aldosterone-induced podocyte injury remains ambiguous. This study aimed to investigate the pathogenic effect of mitochondrial fission both in vivo and in vitro. In an animal model of aldosterone-induced nephropathy, inhibition of the mitochondrial fission protein Drp1 (dynamin-related protein 1) suppressed aldosterone-induced podocyte injury. In cultured podocytes, aldosterone dose-dependently induced Drp1 expression. Knockdown of Drp1 inhibited aldosterone-induced mitochondrial fission, mitochondrial dysfunction and podocyte apoptosis. Furthermore, aldosterone dose-dependently induced p53 expression. Knockdown of p53 inhibited aldosterone-induced Drp1 expression, mitochondrial dysfunction and podocyte apoptosis. These findings implicated that aldosterone-induced mitochondrial dysfunction and podocyte injury mediated by p53/Drp1-dependent mitochondrial fission, which may provide opportunities for therapeutic intervention for podocyte injury. Copyright © 2017, American Journal of Physiology-Renal Physiology.

  16. USP7 inhibitor P22077 inhibits neuroblastoma growth via inducing p53-mediated apoptosis.

    PubMed

    Fan, Y-H; Cheng, J; Vasudevan, S A; Dou, J; Zhang, H; Patel, R H; Ma, I T; Rojas, Y; Zhao, Y; Yu, Y; Zhang, H; Shohet, J M; Nuchtern, J G; Kim, E S; Yang, J

    2013-10-17

    Neuroblastoma (NB) is a common pediatric cancer and contributes to more than 15% of all pediatric cancer-related deaths. Unlike adult tumors, recurrent somatic mutations in NB, such as tumor protein 53 (p53) mutations, occur with relative paucity. In addition, p53 downstream function is intact in NB cells with wild-type p53, suggesting that reactivation of p53 may be a viable therapeutic strategy for NB treatment. Herein, we report that the ubiquitin-specific protease 7 (USP7) inhibitor, P22077, potently induces apoptosis in NB cells with an intact USP7-HDM2-p53 axis but not in NB cells with mutant p53 or without human homolog of MDM2 (HDM2) expression. In this study, we found that P22077 stabilized p53 by inducing HDM2 protein degradation in NB cells. P22077 also significantly augmented the cytotoxic effects of doxorubicin (Dox) and etoposide (VP-16) in NB cells with an intact USP7-HDM2-p53 axis. Moreover, P22077 was found to be able to sensitize chemoresistant LA-N-6 NB cells to chemotherapy. In an in vivo orthotopic NB mouse model, P22077 significantly inhibited the xenograft growth of three NB cell lines. Database analysis of NB patients shows that high expression of USP7 significantly predicts poor outcomes. Together, our data strongly suggest that targeting USP7 is a novel concept in the treatment of NB. USP7-specific inhibitors like P22077 may serve not only as a stand-alone therapy but also as an effective adjunct to current chemotherapeutic regimens for treating NB with an intact USP7-HDM2-p53 axis.

  17. Allicin induces anti-human liver cancer cells through the p53 gene modulating apoptosis and autophagy.

    PubMed

    Chu, Yung-Lin; Ho, Chi-Tang; Chung, Jing-Gung; Raghu, Rajasekaran; Lo, Yi-Chen; Sheen, Lee-Yan

    2013-10-16

    Hepatocellular carcinoma (HCC) is the most prevalent type of liver cancer globally and ranks first among the cancer-related mortalities in Taiwan. This study aims to understand the modes of cell death mechanism induced by allicin, a major phytochemical of crushed garlic, in human hepatoma cells. Our earlier study indicated that allicin induced autophagic cell death in human HCC Hep G2 (p53(wild type)) cells, whereas in the present study, allicin induced apoptotic cell death through caspase-dependent and caspase-independent pathways by reactive oxygen species (ROS) overproduction in human HCC Hep 3B (p53(mutation)) cells. To gain insight into the cell death mechanism in p53 knocked down Hep G2, we silenced the p53 gene using siRNA-mediated silencing. Allicin treatment induced apoptotic cell death in p53 knocked down Hep G2 cells similar to that of Hep 3B cells. These results suggest that allicin induced cell death in human hepatoma cells through either autophagy or apoptosis and might be a potential novel complementary gene therapeutic agent for the treatment of apoptosis-resistant cancer cells.

  18. Stra6, a retinoic acid-responsive gene, participates in p53-induced apoptosis after DNA damage

    PubMed Central

    Carrera, S; Cuadrado-Castano, S; Samuel, J; Jones, G D D; Villar, E; Lee, S W; Macip, S

    2013-01-01

    Stra6 is the retinoic acid (RA)-inducible gene encoding the cellular receptor for holo-retinol binding protein. This transmembrane protein mediates the internalization of retinol, which then upregulates RA-responsive genes in target cells. Here, we show that Stra6 can be upregulated by DNA damage in a p53-dependent manner, and it has an important role in cell death responses. Stra6 expression induced significant amounts of apoptosis in normal and cancer cells, and it was also able to influence p53-mediated cell fate decisions by turning an initial arrest response into cell death. Moreover, inhibition of Stra6 severely compromised p53-induced apoptosis. We also found that Stra6 induced mitochondria depolarization and accumulation of reactive oxygen species, and that it was present not only at the cellular membrane but also in the cytosol. Finally, we show that these novel functions of Stra6 did not require downstream activation of RA signalling. Our results present a previously unknown link between the RA and p53 pathways and provide a rationale to use retinoids to upregulate Stra6, and thus enhance the tumour suppressor functions of p53. This may have implications for the role of vitamin A metabolites in cancer prevention and treatment. PMID:23449393

  19. Delphinidin induces apoptosis via cleaved HDAC3-mediated p53 acetylation and oligomerization in prostate cancer cells

    PubMed Central

    Jeon, Hyelin; Sung, Gi-Jun; Park, Soo-Yeon; Jun, Woo Jin; Lee, Yoo-Hyun; Lee, Jeongmin; Lee, Sang-wook; Yoon, Ho-Geun; Choi, Kyung-Chul

    2016-01-01

    Delphinidin is a major anthocyanidin compound found in various fruits. It has anti-inflammatory, anti-oxidant, and various other biological activities. In this study, we identified the epigenetic modulators that mediate the apoptotic effect of delphinidin in human prostate cancer cells. We found that treatment of LNCaP cells (a p53 wild-type, human prostate cancer cell line) with delphinidin increased caspase-3, −7, and −8 activity, whereas it decreased histone deacetylase activity. Among class I HDACs, the activity of HDAC3 was specifically inhibited by delphinidin. Moreover, the induction of apoptosis by delphinidin was dependent on caspase-mediated cleavage of HDAC3, which results in the acetylation and stabilization of p53. We also observed that delphinidin potently upregulated pro-apoptotic genes that are positively regulated by p53, and downregulated various anti-apoptotic genes. Taken together, these results show that delphinidin induces p53-mediated apoptosis by suppressing HDAC activity and activating p53 acetylation in human prostate cancer LNCaP cells. Therefore, delphinidin may be useful in the prevention of prostate cancer. PMID:27462923

  20. Effect of Mir-122 on Human Cholangiocarcinoma Proliferation, Invasion, and Apoptosis Through P53 Expression

    PubMed Central

    Wu, Cuiping; Zhang, Jinmei; Cao, Xiangang; Yang, Qian; Xia, Dequan

    2016-01-01

    Background Bile duct carcinoma is a common digestive tract tumor with high morbidity and mortality. As a kind of important non-coding RNA, microRNA (miR) plays an important role in post-transcriptional regulation. MiR-122 is the most abundant miR in the liver. Multiple studies have shown that miR-122 level is reduced in a variety of liver tumors and can be used as a specific marker for liver injury. P53 is a classic tumor suppressor gene that can induce tumor cell apoptosis through various pathways. Whether miR-122 affects p53 in bile duct carcinoma still needs investigation. Material/Methods miR inhibitor or mimics was transfected to bile duct carcinoma cells to evaluate its function on proliferation, invasion, apoptosis, and p53 expression. Results MiR-122 overexpression reduced cell invasion and migration ability, and inhibited cell apoptosis and p53 expression. Inhibiting miR-122 caused the opposite results. Conclusions Upregulating miR-122 can suppress bile duct carcinoma cell proliferation and induce apoptosis. MiR-122 could be used as a target for bile duct carcinoma treatment, which provides a new strategy for cholangiocarcinoma patients. PMID:27472451

  1. ATF4 induction through an atypical integrated stress response to ONC201 triggers p53-independent apoptosis in hematological malignancies

    PubMed Central

    Ishizawa, Jo; Kojima, Kensuke; Chachad, Dhruv; Ruvolo, Peter; Ruvolo, Vivian; Jacamo, Rodrigo O.; Borthakur, Gautam; Mu, Hong; Zeng, Zhihong; Tabe, Yoko; Allen, Joshua E.; Wang, Zhiqiang; Ma, Wencai; Lee, Hans C.; Orlowski, Robert; Sarbassov, Dos D.; Lorenzi, Philip L.; Huang, Xuelin; Neelapu, Sattva S.; McDonnell, Timothy; Miranda, Roberto N.; Wang, Michael; Kantarjian, Hagop; Konopleva, Marina; Davis, R. Eric.; Andreeff, Michael

    2016-01-01

    The clinical challenge posed by p53 abnormalities in hematological malignancies requires therapeutic strategies other than standard genotoxic chemotherapies. ONC201 is a first-in-class small molecule that activates p53-independent apoptosis, has a benign safety profile, and is in early clinical trials. We found that ONC201 caused p53-independent apoptosis and cell cycle arrest in cell lines and in mantle cell lymphoma (MCL) and acute myeloid leukemia (AML) samples from patients; these included samples from patients with genetic abnormalities associated with poor prognosis or cells that had developed resistance to the nongenotoxic agents ibrutinib and bortezomib. Moreover, ONC201 caused apoptosis in stem and progenitor AML cells and abrogated the engraftment of leukemic stem cells in mice while sparing normal bone marrow cells. ONC201 caused changes in gene expression similar to those caused by the unfolded protein response (UPR) and integrated stress responses (ISRs), which increase the translation of the transcription factor ATF4 through an increase in the phosphorylation of the translation initiation factor eIF2α. However, unlike the UPR and ISR, the increase in ATF4 abundance in ONC201-treated hematopoietic cells promoted apoptosis and did not depend on increased phosphorylation of eIF2α. ONC201 also inhibited mammalian target of rapamycin complex 1 (mTORC1) signaling, likely through ATF4-mediated induction of the mTORC1 inhibitor DDIT4. Overexpression of BCL-2 protected against ONC201-induced apoptosis, and the combination of ONC201 and the BCL-2 antagonist ABT-199 synergistically increased apoptosis. Thus, our results suggest that by inducing an atypical ISR and p53-independent apoptosis, ONC201 has clinical potential in hematological malignancies. PMID:26884599

  2. What's new in p53

    PubMed Central

    Maritsi, D; Stagikas, D; Charalabopoulos, K; Batistatou, A

    2006-01-01

    p53 is the main intrinsic factor inducing apoptosis by recognizing the external stimuli and activating the p53 responsive genes to an irreversible series of events. P53 activates the transcription of specific proapoptotic genes called p53 target genes. A growing number of p53 responsive genes have been identified and numerous studies have demonstrated that p53 proapoptotic factors such as Noxa, Puma and Perp play cell type specific roles in p53's mediated response to certain stimuli. Perp (p53 apoptosis effector related to PMP-22) is a direct proapoptotic target gene encoding a tetraspan protein. Perp is highly expressed in cells undergoing apoptosis compared to cells under G1 arrest and its overexpression is sufficient to cause cell death in fibroblasts. Noxa is another member of the preapoptotic p53 genes family. When expressed Noxa acts in a BH3 motif-dependent localization to mitochondria, causing structural changes, activation of caspase 9 and release of cytochrome c from mitochondria to cytosol. Puma (p53 mutant of apoptosis) is another critical mediator of p53-dependent apoptosis. P53 binds to Puma-promoter gene sites, leading to puma production. The mtCLIC, a member of intracellular chloride channels, is a cytoplasmic and mitochondrial protein positively regulated by p53. Caspase 10 is induced in p53-dependent manner leading to cellular apoptosis. Other newly announced factors are also involved in p53-regulated apoptosis such as brain-specific angiogenesis inhibitor - 1 (BSAI1), MSOD and GPX genes. A global discussion on this topic is attempted in the present review article. PMID:20351806

  3. What's new in p53?

    PubMed

    Maritsi, D; Stagikas, D; Charalabopoulos, K; Batistatou, A

    2006-07-01

    p53 is the main intrinsic factor inducing apoptosis by recognizing the external stimuli and activating the p53 responsive genes to an irreversible series of events. P53 activates the transcription of specific proapoptotic genes called p53 target genes. A growing number of p53 responsive genes have been identified and numerous studies have demonstrated that p53 proapoptotic factors such as Noxa, Puma and Perp play cell type specific roles in p53's mediated response to certain stimuli. Perp (p53 apoptosis effector related to PMP-22) is a direct proapoptotic target gene encoding a tetraspan protein. Perp is highly expressed in cells undergoing apoptosis compared to cells under G1 arrest and its overexpression is sufficient to cause cell death in fibroblasts. Noxa is another member of the preapoptotic p53 genes family. When expressed Noxa acts in a BH3 motif-dependent localization to mitochondria, causing structural changes, activation of caspase 9 and release of cytochrome c from mitochondria to cytosol. Puma (p53 mutant of apoptosis) is another critical mediator of p53-dependent apoptosis. P53 binds to Puma-promoter gene sites, leading to puma production. The mtCLIC, a member of intracellular chloride channels, is a cytoplasmic and mitochondrial protein positively regulated by p53. Caspase 10 is induced in p53-dependent manner leading to cellular apoptosis. Other newly announced factors are also involved in p53-regulated apoptosis such as brain-specific angiogenesis inhibitor-1 (BSAI1), MSOD and GPX genes. A global discussion on this topic is attempted in the present review article.

  4. Che-1 gene silencing induces osteosarcoma cell apoptosis by inhibiting mutant p53 expression.

    PubMed

    Liu, Ming; Wang, Dan; 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 chromatin 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.

  5. The p53 tumor suppressor protein protects against chemotherapeutic stress and apoptosis in human medulloblastoma cells

    PubMed Central

    Parasido, Erika; Tricoli, Lucas; Sivakumar, Angiela; Mikhaiel, John P.; Yenugonda, Venkata; Rodriguez, Olga C.; Karam, Sana D.; Rood, Brian R.; Avantaggiati, Maria Laura; Albanese, Chris

    2015-01-01

    Medulloblastoma (MB), a primitive neuroectodermal tumor, is the most common malignant childhood brain tumor and remains incurable in about a third of patients. Currently, survivors carry a significant burden of late treatment effects. The p53 tumor suppressor protein plays a crucial role in influencing cell survival in response to cellular stress and while the p53 pathway is considered a key determinant of anti-tumor responses in many tumors, its role in cell survival in MB is much less well defined. Herein, we report that the experimental drug VMY-1-103 acts through induction of a partial DNA damage-like response as well induction of non-survival autophagy. Surprisingly, the genetic or chemical silencing of p53 significantly enhanced the cytotoxic effects of both VMY and the DNA damaging drug, doxorubicin. The inhibition of p53 in the presence of VMY revealed increased late stage apoptosis, increased DNA fragmentation and increased expression of genes involved in apoptosis, including CAPN12 and TRPM8, p63, p73, BIK, EndoG, CIDEB, P27Kip1 and P21cip1. These data provide the groundwork for additional studies on VMY as a therapeutic drug and support further investigations into the intriguing possibility that targeting p53 function may be an effective means of enhancing clinical outcomes in MB. PMID:26540407

  6. Apoptosis in experimental NASH is associated with p53 activation and TRAIL receptor expression.

    PubMed

    Farrell, Geoffrey C; Larter, Claire Z; Hou, Jing Yun; Zhang, Rena H; Yeh, Matthew M; Williams, Jacqueline; dela Pena, Aileen; Francisco, Rona; Osvath, Sarah R; Brooling, John; Teoh, Narcissus; Sedger, Lisa M

    2009-03-01

    We examined extrinsic and intrinsic (endogenous) mitochondrial apoptosis pathways in experimental non-alcoholic steatohepatitis (NASH). To assess extrinsic pathways, we measured hepatic expression of death-inducing cytokine receptors (tumor necrosis factor-alpha-receptor (TNF-R)1, TNF-R2, Fas, and TNFalpha-related apoptosis-inducing ligand-receptor (TRAIL-R) mRNA, TUNEL, caspase 3 activation, liver injury and liver pathology in mice fed a methionine and choline deficient (MCD) diet. For endogenous stress pathways, we determined serum insulin-like growth factor-1 (IGF-1), hepatic p53, Bcl-XL, tBid and p21 expression. Methionine and choline deficient feeding increased alanine aminotransferase (ALT) and apoptosis from day 10, without increases in TNF-R1, TNF-R2, and Fas. However, murine TRAIL receptors, particularly decoyTRAIL-R1/TNFRSFH23 and Killer/DR5 mRNA increased. MCD feeding enhanced hepatic p53 expression, corresponding to approximately 50% fall in serum IGF-1, decreased Bcl-XL, enhanced Bid cleavage to tBid, and up-regulation of p21. Nutritional restitution experiments showed that correcting either methionine or choline deficiency suppressed liver inflammation (extrinsic pathway), but failed to correct apoptosis, IGF-1 or p53. Methionine and choline deficiency lower IGF-1 to de-repress p53 during induction of steatohepatitis. The p53 induced by nutritional stress is biologically active in mediating mitochondrial cell death pathways, but may also be responsible for TRAIL receptor expression, thereby linking intrinsic and exogenous apoptosis pathways in NASH.

  7. Apoptosis and morphological alterations after UVA irradiation in red blood cells of p53 deficient Japanese medaka (Oryzias latipes).

    PubMed

    Sayed, Alla El-Din Hamid; Watanabe-Asaka, Tomomi; Oda, Shoji; Mitani, Hiroshi

    2016-08-01

    Morphological alterations in red blood cells were described as hematological bioindicators of UVA exposure to investigate the sensitivity to UVA in wild type Japanese medaka (Oryzias latipes) and a p53 deficient mutant. The fewer abnormal red blood cells were observed in the p53 mutant fish under the control conditions. After exposure to different doses of UVA radiation (15min, 30min and 60min/day for 3days), cellular and nuclear alterations in red blood cells were analyzed in the UVA exposed fish compared with non-exposed controls and those alterations included acanthocytes, cell membrane lysis, swollen cells, teardrop-like cell, hemolyzed cells and sickle cells. Those alterations were increased after the UVA exposure both in wild type and the p53 deficient fish. Moreover, apoptosis analyzed by acridine orange assay showed increased number of apoptosis in red blood cells at the higher UVA exposure dose. No micronuclei but nuclear abnormalities as eccentric nucleus, nuclear budding, deformed nucleus, and bilobed nucleus were observed in each group. These results suggested that UVA exposure induced both p53 dependent and independent apoptosis and morphological alterations in red blood cells but less sensitive to UVA than Wild type in medaka fish.

  8. Proposed megakaryocytic regulon of p53: the genes engaged to control cell cycle and apoptosis during megakaryocytic differentiation.

    PubMed

    Apostolidis, Pani A; Lindsey, Stephan; Miller, William M; Papoutsakis, Eleftherios T

    2012-06-15

    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.

  9. Dihydromyricetin promotes hepatocellular carcinoma regression via a p53 activation-dependent mechanism

    NASA Astrophysics Data System (ADS)

    Zhang, Qingyu; Liu, Jie; Liu, Bin; Xia, Juan; Chen, Nianping; Chen, Xiaofeng; Cao, Yi; Zhang, Chen; Lu, Caijie; Li, Mingyi; Zhu, Runzhi

    2014-04-01

    The development of antitumor chemotherapy drugs remains a key goal for oncologists, and natural products provide a vast resource for anti-cancer drug discovery. In the current study, we found that the flavonoid dihydromyricetin (DHM) exhibited antitumor activity against liver cancer cells, including primary cells obtained from hepatocellular carcinoma (HCC) patients. In contrast, DHM was not cytotoxic to immortalized normal liver cells. Furthermore, DHM treatment resulted in the growth inhibition and remission of xenotransplanted tumors in nude mice. Our results further demonstrated that this antitumor activity was caused by the activation of the p53-dependent apoptosis pathway via p53 phosphorylation at serine (15Ser). Moreover, our results showed that DHM plays a dual role in the induction of cell death when administered in combination with cisplatin, a common clinical drug that kills primary hepatoma cells but not normal liver cells.

  10. Dihydromyricetin promotes hepatocellular carcinoma regression via a p53 activation-dependent mechanism

    PubMed Central

    Zhang, Qingyu; Liu, Jie; Liu, Bin; Xia, Juan; Chen, Nianping; Chen, Xiaofeng; Cao, Yi; Zhang, Chen; Lu, CaiJie; Li, Mingyi; Zhu, Runzhi

    2014-01-01

    The development of antitumor chemotherapy drugs remains a key goal for oncologists, and natural products provide a vast resource for anti-cancer drug discovery. In the current study, we found that the flavonoid dihydromyricetin (DHM) exhibited antitumor activity against liver cancer cells, including primary cells obtained from hepatocellular carcinoma (HCC) patients. In contrast, DHM was not cytotoxic to immortalized normal liver cells. Furthermore, DHM treatment resulted in the growth inhibition and remission of xenotransplanted tumors in nude mice. Our results further demonstrated that this antitumor activity was caused by the activation of the p53-dependent apoptosis pathway via p53 phosphorylation at serine (15Ser). Moreover, our results showed that DHM plays a dual role in the induction of cell death when administered in combination with cisplatin, a common clinical drug that kills primary hepatoma cells but not normal liver cells. PMID:24717393

  11. The in vitro phosphorylation of p53 by calcium-dependent protein kinase C--characterization of a protein-kinase-C-binding site on p53.

    PubMed

    Delphin, C; Huang, K P; Scotto, C; Chapel, A; Vincon, M; Chambaz, E; Garin, J; Baudier, J

    1997-05-01

    We show that, in vitro, Ca2+-dependent protein kinase C (PKC) phosphorylates recombinant murine p53 protein on several residues contained within a conserved basic region of 25 amino acids, located in the C-terminal part of the protein. Accordingly, synthetic p53-(357-381)-peptide is phosphorylated by PKC at multiple Ser and Thr residues, including Ser360, Thr365, Ser370 and Thr377. We also establish that p53-(357-381)-peptide at micromolar concentrations has the ability to stimulate sequence-specific DNA binding by p53. That stimulation is lost upon phosphorylation by PKC. To further characterise the mechanisms that regulate PKC-dependent phosphorylation of p53-(357-381)-peptide, the phosphorylation of recombinant p53 and p53-(357-381)-peptide by PKC were compared. The results suggest that phosphorylation of full-length p53 on the C-terminal PKC sites is highly dependent on the accessibility of the phosphorylation sites and that a domain on p53 distinct from p53-(357-381)-peptide is involved in binding PKC. Accordingly, we have identified a conserved 27-amino-acid peptide, p53-(320-346)-peptide, within the C-terminal region of p53 and adjacent to residues 357-381 that interacts with PKC in vitro. The interaction between p53-(320-346)-peptide and PKC inhibits PKC autophosphorylation and the phosphorylation of substrates, including p53-(357-381)-peptide, neurogranin and histone H1. Conventional Ca2+-dependent PKC alpha, beta and gamma and the catalytic fragment of PKC (PKM) were nearly equally susceptible to inhibition by p53-(320-346)-peptide. The Ca2+-independent PKC delta was much less sensitive to inhibition. The significance of these findings for understanding the in vivo phosphorylation of p53 by PKC are discussed.

  12. TAF6δ Controls Apoptosis and Gene Expression in the Absence of p53

    PubMed Central

    Wilhelm, Emmanuelle; Pellay, François-Xavier; Benecke, Arndt; Bell, Brendan

    2008-01-01

    Background Life and death decisions of metazoan cells hinge on the balance between the expression of pro- versus anti-apoptotic gene products. The general RNA polymerase II transcription factor, TFIID, plays a central role in the regulation of gene expression through its core promoter recognition and co-activator functions. The core TFIID subunit TAF6 acts in vitro as an essential co-activator of transcription for the p53 tumor suppressor protein. We previously identified a splice variant of TAF6, termed TAF6δ that can be induced during apoptosis. Methodology/Principal Findings To elucidate the impact of TAF6δ on cell death and gene expression, we have employed modified antisense oligonucleotides to enforce expression of endogenous TAF6δ. The induction of endogenous TAF6δ triggered apoptosis in tumor cell lines, including cells devoid of p53. Microarray experiments revealed that TAF6δ activates gene expression independently of cellular p53 status. Conclusions Our data define TAF6δ as a pivotal node in a signaling pathway that controls gene expression programs and apoptosis in the absence of p53. PMID:18628956

  13. Hyperglycemia induces apoptosis and p53 mobilization to mitochondria in RINm5F cells.

    PubMed

    Ortega-Camarillo, C; Guzmán-Grenfell, A M; García-Macedo, R; Rosales-Torres, A M; Avalos-Rodríguez, A; Durán-Reyes, G; Medina-Navarro, R; Cruz, M; Díaz-Flores, M; Kumate, J

    2006-01-01

    The mechanisms related to hyperglycemia-induced pancreatic beta-cell apoptosis are poorly defined. Rat insulin-producing cells (RINm5F) cultured in high glucose concentrations (30 mM) showed increased apoptosis and protein p53 translocation to mitochondria. In addition, hyperglycemia induced both the disruption of mitochondrial membrane potential (Delta psi (m)), and an increase in reactive oxygen species (ROS), as shown by fluorescence changes of JC-1 and dichlorodihydrofluorescein-diacetate (DCDHF-DA), respectively. The increased intracellular ROS by high glucose exposure was blunted by mitochondrial-function and NADPH-oxidase inhibitors. We postulate that the concomitant mobilization of p53 protein to the mitochondria and the subsequent changes on the Delta psi (m), lead to an important pancreatic beta-cell apoptosis mechanism induced by oxidative stress caused by hyperglycemia.

  14. All-trans retinoic acid induces p53-depenent apoptosis in human hepatocytes by activating p14 expression via promoter hypomethylation.

    PubMed

    Heo, Shin-Hee; Kwak, Juri; Jang, Kyung Lib

    2015-06-28

    All-trans retinoic acid (ATRA), the most biologically active metabolite of vitamin A, has been extensively studied for the prevention and treatment of cancer; however, the underlying mechanism of its anti-cancer potential is still unclear. Here we found that ATRA induces apoptosis in p53-positive HepG2 cells, but not in p53-negative Hep3B cells. For this effect, ATRA activated p14 expression via promoter hypomethylation, resulting in ubiquitin-dependent degradation of mouse double minute 2 (MDM2) and subsequent stabilization of p53. The potential of ATRA to stabilize p53 was almost completely abolished by knock-down of p14 in HepG2 cells and was not observed in p14-negative A549 cells. Upregulation of p14 also abolished the self-regulatory potential of p53 to repress p14 expression via DNA methylation and transcriptionally activate MDM2 expression. The accumulated p53 then activated several apoptosis-related molecules, including Bax, PUMA, caspase-9, Bid, caspase-8, caspase-3, and PARP. Ectopic expression of DNA methyltransferase 1 almost completely abolished the potential of ATRA to activate the p14-MDM2-p53 pathway and induce p53-dependent apoptosis. Therefore, we conclude that ATRA induces p14 promoter hypomethylation to trigger apoptosis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  15. Effect of C-terminal deletion of P53 on heat induced CD95 expression and apoptosis in a rat histiocytoma.

    PubMed

    Sreedhar, Amere S; Pardhasaradhi, Bobbili V V; Khar, Ashok; Srinivas, Usha K

    2002-06-06

    Tumor suppressor gene product p53 in its wild-type conformation, is an effector of apoptosis. A rat histiocytic tumor, AK-5 which has a rearranged and mutated p53 gene undergoes apoptosis upon heat shock through surface expression of CD95 receptor. DNA sequence analysis of p53 gene from tumor cells revealed a deletion of 'C' at nucleotide position 942 and an addition of 'A' at position 1055. Deletion of one nucleotide caused premature termination of p53 protein which resulted in shorter p53 protein with an altered sequence from amino acids 315 to 341. Altered p53 was unable to protect BC-8, a single cell clone of AK-5 cells from apoptosis upon heat shock. BC-8 cells transfected with a wild-type p53gene (3B4 cells) were resistant to heat induced apoptosis and did not show the expression CD95 death receptor. Inhibition of p53 expression by using antisense oligo induced apoptosis upon heat shock in 3B4 cells. Similarly, inhibition of CD95 expression by antisense oligo inhibited heat induced apoptosis in BC-8 cells. In addition, cell cycle regulatory molecules, cdc2 and cdk2 are differentially regulated in a non-cell cycle dependent manner in these tumor cells. These results, in view of lack of heat shock response in BC-8 cells suggest a complex interaction between p53, CD95 and hsp70 which determines the fate of the cell. In the absence of functional p53, CD95 appears to be an effector of apoptosis in BC-8 cells.

  16. Eurycomanone induce apoptosis in HepG2 cells via up-regulation of p53

    PubMed Central

    Zakaria, Yusmazura; Rahmat, Asmah; Pihie, Azimahtol Hawariah Lope; Abdullah, Noor Rain; Houghton, Peter J

    2009-01-01

    Background Eurycomanone is a cytotoxic compound found in Eurycoma longifolia Jack. Previous studies had noted the cytotoxic effect against various cancer cell lines. The aim of this study is to investigate the cytotoxicity against human hepato carcinoma cell in vitro and the mode of action. The cytotoxicity of eurycomanone was evaluated using MTT assay and the mode of cell death was detected by Hoechst 33258 nuclear staining and flow cytometry with Annexin-V/propidium iodide double staining. The protein expression Bax, Bcl-2, p53 and cytochrome C were studied by flow cytometry using a spesific antibody conjugated fluorescent dye to confirm the up-regulation of p53 and Bax in cancer cells. Results The findings suggested that eurycomanone was cytotoxic on cancerous liver cell, HepG2 and less toxic on normal cells Chang's liver and WLR-68. Furthermore, various methods proved that apoptosis was the mode of death in eurycomanone-treated HepG2 cells. The characteristics of apoptosis including chromatin condensation, DNA fragmentation and apoptotic bodies were found following eurycomanone treatment. This study also found that apoptotic process triggered by eurycomanone involved the up-regulation of p53 tumor suppressor protein. The up-regulation of p53 was followed by the increasing of pro-apoptotic Bax and decreasing of anti-apoptotic Bcl-2. The increased of cytochrome C levels in cytosol also results in induction of apoptosis. Conclusion The data suggest that eurycomanone was cytotoxic on HepG2 cells by inducing apoptosis through the up-regulation of p53 and Bax, and down-regulation of Bcl-2. PMID:19508737

  17. High glucose promotes nascent nephron apoptosis via NF-kappaB and p53 pathways.

    PubMed

    Chen, Yun-Wen; Chenier, Isabelle; Chang, Shiao-Ying; Tran, Stella; Ingelfinger, Julie R; Zhang, Shao-Ling

    2011-01-01

    A hyperglycemic environment in utero reduces kidney size and nephron number due to nascent nephron apoptosis. However, the underlying mechanisms are incompletely understood. The present study investigated whether the nascent nephron apoptosis promoted by high glucose is mediated via the transcription factor NF-κB and p53 signaling pathways. Neonatal mouse kidneys from the offspring of nondiabetic, diabetic, and insulin-treated diabetic dams were used for in vivo studies, and MK4 cells, an embryonic metanephric mesenchymal (MM) cell line, were used for in vitro studies. Neonatal kidneys of the offspring of diabetic mothers exhibited an increased number of apoptotic cells and reactive oxygen species (ROS) generation, enhanced NF-κB activation, and nuclear translocation of its subunits (p50 and p65 subunits) as well as phosphorylation (Ser 15) of p53 compared with kidneys of offspring of nondiabetic mothers. Insulin treatment of diabetic dams normalized these parameters in the offspring. In vitro, high-glucose (25 mM) induced ROS generation and significantly increased MK4 cell apoptosis and caspase-3 activity via activation of NF-κB pathway, with p53 phosphorylation and nuclear translocation compared with normal glucose (5 mM). These changes in a high-glucose milieu were prevented by transient transfection of small interfering RNAs for dominant negative IκBα or IKK or p53. Our data demonstrate that high glucose-induced nascent nephron apoptosis is mediated, at least in part, via ROS generation and the activation of NF-κB and p53 pathways.

  18. p53 mutant human glioma cells are sensitive to UV-C-induced apoptosis due to impaired cyclobutane pyrimidine dimer removal.

    PubMed

    Batista, Luis F Z; Roos, Wynand P; Kaina, Bernd; Menck, Carlos F M

    2009-02-01

    The p53 protein is a key regulator of cell responses to DNA damage, and it has been shown that it sensitizes glioma cells to the alkylating agent temozolomide by up-regulating the extrinsic apoptotic pathway, whereas it increases the resistance to chloroethylating agents, such as ACNU and BCNU, probably by enhancing the efficiency of DNA repair. However, because these agents induce a wide variety of distinct DNA lesions, the direct importance of DNA repair is hard to access. Here, it is shown that the induction of photoproducts by UV light (UV-C) significantly induces apoptosis in a p53-mutated glioma background. This is caused by a reduced level of photoproduct repair, resulting in the persistence of DNA lesions in p53-mutated glioma cells. UV-C-induced apoptosis in p53 mutant glioma cells is preceded by strong transcription and replication inhibition due to blockage by unrepaired photolesions. Moreover, the results indicate that UV-C-induced apoptosis of p53 mutant glioma cells is executed through the intrinsic apoptotic pathway, with Bcl-2 degradation and sustained Bax and Bak up-regulation. Collectively, the data indicate that unrepaired DNA lesions induce apoptosis in p53 mutant gliomas despite the resistance of these gliomas to temozolomide, suggesting that efficiency of treatment of p53 mutant gliomas might be higher with agents that induce the formation of DNA lesions whose global genomic repair is dependent on p53.

  19. Interleukin-13 interferes with activation-induced t-cell apoptosis by repressing p53 expression

    PubMed Central

    Yang, Li; Xu, Ling-Zhi; Liu, Zhi-Qiang; Yang, Gui; Geng, Xiao-Rui; Mo, Li-Hua; Liu, Zhi-Gang; Zheng, Peng-Yuan; Yang, Ping-Chang

    2016-01-01

    The etiology and the underlying mechanism of CD4+ T-cell polarization are unclear. This study sought to investigate the mechanism by which interleukin (IL)-13 prevents the activation-induced apoptosis of CD4+ T cells. Here we report that CD4+ T cells expressed IL-13 receptor α2 in the intestine of sensitized mice. IL-13 suppressed both the activation-induced apoptosis of CD4+ T cells and the expression of p53 and FasL. Exposure to recombinant IL-13 inhibited activation-induced cell death (AICD) along with the expression of p53, caspase 3, and tumor necrosis factor-α in CD4+ T cells. Administration of an anti-IL-13 antibody enhanced the effect of specific immunotherapy on allergic inflammation in the mouse intestine, enforced the expression of p53 in intestinal CD4+ T cells, and enhanced the frequency of CD4+ T-cell apoptosis upon challenge with specific antigens. In summary, blocking IL-13 enhances the therapeutic effect of antigen-specific immunotherapy by regulating apoptosis and thereby enforcing AICD in CD4+ T cells. PMID:26189367

  20. Deubiquitination of Tip60 by USP7 determines the activity of the p53-dependent apoptotic pathway.

    PubMed

    Dar, Ashraf; Shibata, Etsuko; Dutta, Anindya

    2013-08-01

    Tip60 is an essential acetyltransferase required for acetylation of nucleosomal histones and other nonhistone proteins. Tip60 acetylates the p53 tumor suppressor at lysine 120 (K120), a modification essential for p53-dependent induction of PUMA and apoptosis. It is known that Tip60 is turned over in cells by the ubiquitin-proteasome system. However, the deubiquitinase activity for stabilizing Tip60 is unknown. Here we show that USP7 interacts with and deubiquitinates Tip60 both in vitro and in vivo. USP7 deubiquitinase activity is required for the stabilization of Tip60 in order to operate an effective p53-dependent apoptotic pathway in response to genotoxic stress. Inhibiting USP7 with the small-molecule inhibitor P22077 attenuates the p53-dependent apoptotic pathway by destabilizing Tip60. P22077, however, is still cytotoxic, and this is partly due to destabilization of Tip60.

  1. Deubiquitination of Tip60 by USP7 Determines the Activity of the p53-Dependent Apoptotic Pathway

    PubMed Central

    Dar, Ashraf; Shibata, Etsuko

    2013-01-01

    Tip60 is an essential acetyltransferase required for acetylation of nucleosomal histones and other nonhistone proteins. Tip60 acetylates the p53 tumor suppressor at lysine 120 (K120), a modification essential for p53-dependent induction of PUMA and apoptosis. It is known that Tip60 is turned over in cells by the ubiquitin-proteasome system. However, the deubiquitinase activity for stabilizing Tip60 is unknown. Here we show that USP7 interacts with and deubiquitinates Tip60 both in vitro and in vivo. USP7 deubiquitinase activity is required for the stabilization of Tip60 in order to operate an effective p53-dependent apoptotic pathway in response to genotoxic stress. Inhibiting USP7 with the small-molecule inhibitor P22077 attenuates the p53-dependent apoptotic pathway by destabilizing Tip60. P22077, however, is still cytotoxic, and this is partly due to destabilization of Tip60. PMID:23775119

  2. HSP25 down-regulation enhanced p53 acetylation by dissociation of SIRT1 from p53 in doxorubicin-induced H9c2 cell apoptosis.

    PubMed

    Zhang, Chi; Qu, Shunlin; Wei, Xing; Feng, Yansheng; Zhu, Honglin; Deng, Jia; Wang, Kangkai; Liu, Ke; Liu, Meidong; Zhang, Huali; Xiao, Xianzhong

    2016-03-01

    Heat shock proteins (HSPs) play important roles in cellular stress resistance. Previous reports had already suggested that HSP27 played multiple roles in preventing doxorubicin-induced cardiotoxicity. Although HSP25 might have biological functions similar to its human homolog HSP27, the mechanism of HSP25 is still unclear in doxorubicin-induced cardiomyocyte apoptosis. To investigate HSP25 biological function on doxorubicin-induced apoptosis, flow cytometry was employed to analyze cell apoptosis in over-expressing HSP25 H9c2 cells in presence of doxorubicin. Unexpectedly, the H9c2 cells of over-expressing HSP25 have no protective effect on doxorubicin-induced apoptosis. Moreover, no detectable interactions were detected by coimmunoprecipitation between HSP25 and cytochrome c, and HSP25 over-expression failed in preventing cytochrome c release induced by doxorubicin. However, down-regulation of endogenous HSP25 by a specific small hairpin RNA aggravates apoptosis in H9c2 cells. Subsequent studies found that HSP25, but not HSP90, HSP70, and HSP20, interacted with SIRT1. Knockdown of HSP25 decreased the interaction between SIRT1 and p53, leading to increased p53 acetylation on K379, up-regulated pro-apoptotic Bax protein expression, induced cytochrome c release, and triggered caspase-3 and caspase-9 activation. These findings indicated a novel mechanism by which HSP25 regulated p53 acetylation through dissociation of SIRT1 from p53 in doxorubicin-induced H9c2 cell apoptosis.

  3. Curcumin enhances temsirolimus-induced apoptosis in human renal carcinoma cells through upregulation of YAP/p53

    PubMed Central

    Xu, Shan; Yang, Zheng; Fan, Yizeng; Guan, Bing; Jia, Jing; Gao, Yang; Wang, Ke; Wu, Kaijie; Wang, Xinyang; Zheng, Pengsheng; He, Dalin; Guo, Peng

    2016-01-01

    Curcumin has frequently been used as a therapeutic agent in the treatment of various types of disease and is known to enhance the drug sensitivity of cells. In the present study, the combined effect of curcumin and temsirolimus treatment on apoptosis in human renal cell carcinoma (RCC) cells was investigated. Temsirolimus is an inhibitor of the mechanistic target of rapamycin signaling pathway and used in the first-line treatment of metastatic RCC. It was demonstrated that curcumin combined with temsirolimus markedly induced apoptosis in RCC cells, however this effect was not observed following curcumin or temsirolimus treatment alone. Co-treatment with temsirolimus and curcumin led to the activation of cleaved poly ADP-ribose polymerase and caspase 3, upregulation of p53 expression and nuclear translocation, and downregulation of B-cell lymphoma 2 protein expression. Furthermore, curcumin treatment was demonstrated to increase Yes-associated protein (YAP) expression in a time-dependent manner, which was concurrent with the curcumin-induced expression pattern of p53 after 2 h. In addition, knockdown of YAP by small interfering RNA caused the attenuation of curcumin-induced increased p53 expression in RCC cells. In conclusion, the present results indicate that combined curcumin and temsirolimus treatment has a synergistic effect on apoptosis in human RCC cells, through the activation of p53. Mechanistically, YAP is essential in the induction of p53 expression by curcumin. Furthermore, the results suggest that pre-treatment or co-treatment of cells with low concentration curcumin enhances the response to targeted drugs, and this presents a potentially novel and efficient strategy to overcome drug resistance in human RCC. PMID:28105206

  4. Benzo(a)pyrene Induced p53 Mediated Male Germ Cell Apoptosis: Synergistic Protective Effects of Curcumin and Resveratrol

    PubMed Central

    Banerjee, Bhaswati; Chakraborty, Supriya; Ghosh, Debidas; Raha, Sanghamitra; Sen, Parimal C.; Jana, Kuladip

    2016-01-01

    Benzo(a)pyrene (B(a)P) is an environmental toxicant that induces male germ cell apoptosis. Curcumin and resveratrol are phytochemicals with cytoprotective and anti-oxidative properties. At the same time resveratrol is also a natural Aryl hydrocarbon Receptor (AhR) antagonist. Our present study in isolated testicular germ cell population from adult male Wistar rats, highlighted the synergistic protective effect of curcumin and resveratrol against B(a)P induced p53 mediated germ cell apoptosis. Curcumin-resveratrol significantly prevented B(a)P induced decrease in sperm cell count and motility, as well as increased serum testosterone level. Curcumin-resveratrol co-treatment actively protected B(a)P induced testicular germ cell apoptosis. Curcumin-resveratrol co-treatment decreased the expression of pro-apoptotic proteins like cleaved caspase 3, 8 and 9, cleaved PARP, Apaf1, FasL, tBid. Curcumin-resveratrol co-treatment decreased Bax/Bcl2 ratio, mitochondria to cytosolic translocation of cytochrome c and activated the survival protein Akt. Curcumin-resveratrol decreased the expression of p53 dependent apoptotic genes like Fas, FasL, Bax, Bcl2, and Apaf1. B(a)P induced testicular reactive oxygen species (ROS) generation and oxidative stress were significantly ameliorated with curcumin and resveratrol. Curcumin-resveratrol co-treatment prevented B(a)P induced nuclear translocation of AhR and CYP1A1 (Cytochrome P4501A1) expression. The combinatorial treatment significantly inhibited B(a)P induced ERK 1/2, p38 MAPK and JNK 1/2 activation. B(a)P treatment increased the expression of p53 and its phosphorylation (p53 ser 15). Curcumin-resveratrol co-treatment significantly decreased p53 level and its phosphorylation (p53 ser 15). The study concludes that curcumin-resveratrol synergistically modulated MAPKs and p53, prevented oxidative stress, regulated the expression of pro and anti-apoptotic proteins as well as the proteins involved in B(a)P metabolism thus protected germ

  5. Novel structurally similar chromene derivatives with opposing effects on p53 and apoptosis mechanisms in colorectal HCT116 cancer cells.

    PubMed

    Lima, Cristovao F; Costa, Marta; Proença, M F; Pereira-Wilson, Cristina

    2015-05-25

    In the present work, novel chromene derivatives fused with the imidazo[1,2-a]pyridine nucleus were tested for their anticancer potential in the human colorectal cancer HCT116 cells. Compounds 2a and 2c showed significant growth inhibitory activity with GI50 of 15 μM and 11 μM, respectively. Compound 2c, the most potent, has a carbamate group in position 8 of the pyridine ring, and showed significant cell cycle arrest and induction of cell death by apoptosis, even at 5 μM. Besides different potencies, chromene analogs 2a and 2c showed different mechanisms of action. Whereas the carbamate-free chromene 2a induced cell cycle arrest at G1/G0 phase, compound 2c showed to arrest cell cycle at both S and G2 phases. Chromene derivative 2a at concentrations higher than its GI50 remarkably induced caspases-dependent apoptosis in a p53-independent manner. On the other hand, compound 2c increased significantly p53 levels and induced apoptosis in a p53- and caspases-dependent manner, even at concentrations lower than its GI50. Both compounds increased the Bax/Bcl-2 ratio, induced mitochondria depolarization and activated MAP kinases. In conclusion, two novel and structurally similar chromene derivatives showed cytotoxicity to HCT16 cells through opposing effects on p53 levels and apoptosis mechanisms, which may be relevant for further development of drugs acting on distinct molecular targets useful in the treatment of cancers with different genetic profiles and for personalized medicine. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Knockdown of CDK2AP1 in Primary Human Fibroblasts Induces p53 Dependent Senescence

    PubMed Central

    Alsayegh, Khaled N.; Gadepalli, Venkat S.; Iyer, Shilpa; Rao, Raj R.

    2015-01-01

    Cyclin Dependent Kinase-2 Associated Protein-1 (CDK2AP1) is known to be a tumor suppressor that plays a role in cell cycle regulation by sequestering monomeric CDK2, and targeting it for proteolysis. A reduction of CDK2AP1 expression is considered to be a negative prognostic indicator in patients with oral squamous cell carcinoma and also associated with increased invasion in human gastric cancer tissue. CDK2AP1 overexpression was shown to inhibit growth, reduce invasion and increase apoptosis in prostate cancer cell lines. In this study, we investigated the effect of CDK2AP1 downregulation in primary human dermal fibroblasts. Using a short-hairpin RNA to reduce its expression, we found that knockdown of CDK2AP1in primary human fibroblasts resulted in reduced proliferation and in the induction of senescence associated beta-galactosidase activity. CDK2AP1 knockdown also resulted in a significant reduction in the percentage of cells in the S phase and an accumulation of cells in the G1 phase of the cell cycle. Immunocytochemical analysis also revealed that the CDK2AP1 knockdown significantly increased the percentage of cells that exhibited γ-H2AX foci, which could indicate presence of DNA damage. CDK2AP1 knockdown also resulted in increased mRNA levels of p53, p21, BAX and PUMA and p53 protein levels. In primary human fibroblasts in which p53 and CDK2AP1 were simultaneously downregulated, there was: (a) no increase in senescence associated beta-galactosidase activity, (b) decrease in the number of cells in the G1-phase and increase in number of cells in the S-phase of the cell cycle, and (c) decrease in the mRNA levels of p21, BAX and PUMA when compared with CDK2AP1 knockdown only fibroblasts. Taken together, this suggests that the observed phenotype is p53 dependent. We also observed a prominent increase in the levels of ARF protein in the CDK2AP1 knockdown cells, which suggests a possible role of ARF in p53 stabilization following CDK2AP1 knockdown. Altogether

  7. Cellular senescence: ex vivo p53-dependent asymmetric cell kinetics

    PubMed Central

    2001-01-01

    Although senescence is a defining property of euploid mammalian cells, its physiologic basis remains obscure. Previously, cell kinetics properties of normal tissue cells have not been considered in models for senescence. We now provide evidence that senescence is in fact the natural consequence of normal in vivo somatic stem cell kinetics extended in culture. This concept of senescence is based on our discovery that cells engineered to conditionally express the well-recognized tumor suppressor protein and senescence factor, p53, exhibit asymmetric cell kinetics. In vivo, asymmetric cell kinetics are essential for maintenance of somatic stem cells; ex vivo, the same cell kinetics yield senescence as a simple kinetic endpoint. This new “asymmetric cell kinetics model” for senescence suggests novel strategies for the isolation and propagation of somatic tissue stem cells in culture. PMID:12488624

  8. Chronic doxorubicin cardiotoxicity is mediated by oxidative DNA damage-ATM-p53-apoptosis pathway and attenuated by pitavastatin through the inhibition of Rac1 activity.

    PubMed

    Yoshida, Masashi; Shiojima, Ichiro; Ikeda, Hiroyuki; Komuro, Issei

    2009-11-01

    Doxorubicin is known to have cumulative dose-dependent cardiotoxicity, and a tumor suppressor protein p53 has been implicated in the pathogenesis of doxorubicin cardiotoxicity. However, how p53 is induced by doxorubicin and mediates the cardiotoxic effects of doxorubicin remains elusive. In cultured cardiac myocytes, doxorubicin induced oxidative stress, DNA damage, ATM activation, and p53 induction. A free radical scavenger NAC attenuated all of these events, whereas an ATM kinase inhibitor wortmannin attenuated doxorubicin-induced ATM activation and p53 induction but not oxidative stress. Doxorubicin treatment in vivo also induced oxidative stress, DNA damage, ATM activation, and p53 accumulation. These observations suggest that p53 induction by doxorubicin is mediated by oxidative DNA damage-ATM pathway. Doxorubicin-induced contractile dysfunction and myocyte apoptosis in vivo were attenuated in heterozygous p53 deficient mice and cardiac-restricted Bcl-2 transgenic mice, suggesting that myocyte apoptosis plays a central role downstream of p53 in doxorubicin cardiotoxicity. We also tested whether pitavastatin exerts protective effects on doxorubicin cardiotoxicity. Pitavastatin attenuated doxorubicin-induced oxidative stress, DNA damage, ATM activation, p53 accumulation, and apoptosis in vitro. Pitavastatin also attenuated myocyte apoptosis and contractile dysfunction in vivo. The beneficial effects of pitavastatin were reversed by intermediate products of the mevalonate pathway that are required for the activation of Rac1, and Rac1 inhibitor exhibited cardioprotective effects comparable to those of pitavastatin. These data collectively suggest that doxorubicin-induced cardiotoxicity is mediated by oxidative DNA damage-ATM-p53-apoptosis pathway, and is attenuated by pitavastatin through its antioxidant effect involving Rac1 inhibition.

  9. The contrasting activity of iodido versus chlorido ruthenium and osmium arene azo- and imino-pyridine anticancer complexes: control of cell selectivity, cross-resistance, p53 dependence, and apoptosis pathway.

    PubMed

    Romero-Canelón, Isolda; Salassa, Luca; Sadler, Peter J

    2013-02-14

    Organometallic half-sandwich complexes [M(p-cymene)(azo/imino-pyridine)X](+) where M = Ru(II) or Os(II) and X ═ Cl or I, exhibit potent antiproliferative activity toward a range of cancer cells. Not only are the iodido complexes more potent than the chlorido analogues, but they are not cross-resistant with the clinical platinum drugs cisplatin and oxaliplatin. They are also more selective for cancer cells versus normal cells (fibroblasts) and show high accumulation in cell membranes. They arrest cell growth in G1 phase in contrast to cisplatin (S phase) with a high incidence of late-stage apoptosis. The iodido complexes retain potency in p53 mutant colon cells. All complexes activate caspase 3. In general, antiproliferative activity is greatly enhanced by low levels of the glutathione synthase inhibitor l-buthionine sulfoxime. The work illustrates how subtle changes to the design of low-spin d(6) metal complexes can lead to major changes in cellular metabolism and to potent complexes with novel mechanisms of anticancer activity.

  10. Resveratrol protects cardiomyocytes from doxorubicin-induced apoptosis through the AMPK/P53 pathway.

    PubMed

    Liu, Mi-Hua; Lin, Xiao-Long; Guo, Dong-Ming; Zhang, Yuan; Yuan, Cong; Tan, Tian-Ping; Chen, Yu-Dan; Wu, Shao-Jian; Ye, Zu-Feng; He, Jun

    2016-02-01

    Doxorubicin (DOX) is an efficient drug used in cancer therapy; however, it has severe cardiotoxic side effects. The aim of the present study was to investigate the effects of resveratrol on the adenosine monophosphate-activated protein kinase (AMPK)/P53 pathway in mediating DOX-induced cytotoxicity. H9c2 cells were exposed to 5 µM DOX for 24 h to establish a model of DOX-induced cardiotoxicity. DOX administration amplified P53 and B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) expression and decreased Bcl-2 expression in H9c2 cells. Resveratrol increased the cell viability and decreased the apoptotic rate. In addition, resveratrol markedly increased the phosphorylation of AMPK. Of note, resveratrol protected against DOX-induced increases of P53 and Bax and also prevented the downregulation of Bcl-2 in H9c2 cells. Furthermore, AMPK inhibitor Compound C abolished the protective effects of resveratrol. The results of the present study therefore indicated that resveratrol protected H9c2 cells from DOX-induced apoptosis via the AMPK/P53 pathway.

  11. 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

  12. Apoptosis, proliferation and p53 gene expression of H. pylori associated gastric epithelial lesions

    PubMed Central

    Zhang, Zhong; Yuan, Yuan; Gao, Hua; Dong, Ming; Wang, Lan; Gong, Yue-Hua

    2001-01-01

    AIM: To study the relationship between Helicobacter pylori (H. pylori) and gastric carcinoma and its possible pathogenesis by H. pylori. METHODS: DNEL technique and immunohistochemical technique were used to study the state of apoptosis, proliferation and p53 gene expression. A total of 100 gastric mucosal biopsy specimens, including 20 normal mucosa, 30 H. pylori-negative and 30 H. pylori-positive gastric precancerous lesions along with 20 gastric carcinomas were studied. RESULTS: There were several apoptotic cells in the superficial epithelium and a few proliferative cells within the neck of gastric glands, and no p53 protein expression in normal mucosa. In gastric carcinoma, there were few apoptotic cells, while there were a large number of proliferative cells, and expression of p53 protein significantly was increased. In the phase of metaplasia, the apoptotic index (AI, 4.36% ± 1.95%), proliferative index (PI, 19.11% ± 6. 79%) and positivity of p53 expression (46.7%) in H. pylori-positive group were higher than those in normal mucosa (P < 0.01). AI in H. pylori-positive group was higher than that in H. pylori-negative group (3.81% ± 1.76%), PI in H. pylori-positive group was higher than that in H. pylori-negative group (12.25% ± 5.63%, P < 0.01). In the phase of dysplasia, AI (2.31% ± 1.10%) in H. pylori-positive group was lower (3.05% ± 1.29%) than that in H. pylori-negative group, but PI (33.89% ± 11.65%) was significantly higher (22.09% ± 80.18%, P < 0.01). In phases of metaplasia, dysplasia and gastric cancer in the H. pylori-positive group, AIs had an evidently graduall decreasing trend (P < 0.01), while PIs had an evidently gradual increasing trend (P < 0.05 or P < 0.01), and there was also a trend of gradual increase in the expression of p53 gene. CONCLUSION: In the course of the formation of gastric carcinoma, proliferation of gastric mucosa can be greatly increased by H. pylori, and H. pylori can induce apoptosis in the phase of metaplasia, but

  13. Methyl methanesulfonate induces apoptosis in p53-deficient H1299 and Hep3B cells through a caspase 2- and mitochondria-associated pathway.

    PubMed

    Jiang, Ying; Zhang, Xiao-Yun; Sun, Li; Zhang, Guang-Lin; Duerksen-Hughes, Penelope; Zhu, Xin-Qiang; Yang, Jun

    2012-11-01

    Methyl methanesulfonate (MMS) has been shown to induce apoptosis in various cell types through p53-dependent pathways. Nevertheless, pharmacological and genetic blockade of p53 functions results in similar or delayed sensitivity to MMS treatment, suggesting the presence of p53-independent apoptotic mechanisms. To understand the p53-independent mechanisms that are engaged during MMS-induced apoptosis, we established MMS-induced apoptotic cell models using p53-deficient H1299 and Hep3B cells. Our results demonstrated that MMS at concentrations of 50, 100, 200, 400 and 800 μM induced the formation of gammaH2AX foci, and that at higher concentrations, 400 and 800 μM, MMS treatment led to apoptosis in the two cell lines. This apoptotic cell death was concurrent with the loss of mitochondrial membrane potential, nuclear-cytosolic translocation of active caspase 2, release of cytochrome c from mitochondria, and the cleavage of caspase 9, caspase 3 and PARP. However, MMS-induced DNA damage failed to stabilize the p53 family members TAp73 and DNp73. These results demonstrated a p53- and p73-independent mechanism for MMS-induced apoptosis that involves the nuclear-cytosolic translocation of active caspase 2 as well as the mitochondria-mediated pathway.

  14. p53 controls radiation-induced gastrointestinal syndrome in mice independent of apoptosis.

    PubMed

    Kirsch, David G; Santiago, Philip M; di Tomaso, Emmanuelle; Sullivan, Julie M; Hou, Wu-Shiun; Dayton, Talya; Jeffords, Laura B; Sodha, Pooja; Mercer, Kim L; Cohen, Rhianna; Takeuchi, Osamu; Korsmeyer, Stanley J; Bronson, Roderick T; Kim, Carla F; Haigis, Kevin M; Jain, Rakesh K; Jacks, Tyler

    2010-01-29

    Acute exposure to ionizing radiation can cause lethal damage to the gastrointestinal (GI) tract, a condition called the GI syndrome. Whether the target cells affected by radiation to cause the GI syndrome are derived from the epithelium or endothelium and whether the target cells die by apoptosis or other mechanisms are controversial issues. Studying mouse models, we found that selective deletion of the proapoptotic genes Bak1 and Bax from the GI epithelium or from endothelial cells did not protect mice from developing the GI syndrome after sub-total-body gamma irradiation. In contrast, selective deletion of p53 from the GI epithelium, but not from endothelial cells, sensitized irradiated mice to the GI syndrome. Transgenic mice overexpressing p53 in all tissues were protected from the GI syndrome after irradiation. These results suggest that the GI syndrome is caused by the death of GI epithelial cells and that these epithelial cells die by a mechanism that is regulated by p53 but independent of apoptosis.

  15. Expression of apoptosis regulatory proteins p53, bcl-2 and bax in recurrent aphthous ulceration.

    PubMed

    Pinto Rodrigues, J F N; Fujiyama Oshima, C T; Ribeiro Paiotti, A P; Franco, M; Miki Ihara, S S; Ribeiro, D A

    2012-10-01

    Recurrent aphthous ulceration (RAU) is considered to be an acute inflammatory disease of unknown pathogenesis. Apoptosis may represent an important event in the control of inflammation. The aim of this study was to investigate apoptosis process in RAU using immunohistochemistry. We studied the expression and location of p53, bcl-2 and bax in ulcerated lesions clinically diagnosed as RAU (n = 12) and compared it with that of oral clinically normal mucosa (n = 6) and of other inflammatory chronic disease such as oral fibrous inflammatory hyperplasia (FIH; n = 18). Significant statistically differences (n < 0.05) in p53 expression were noticed in RAU when compared with normal mucosa. No significant statistically differences (P > 0.05) were noticed between FIH and RAU. Bcl-2 and bax did not show remarkable differences between groups. Taken together, the data suggest that RAU induces p53 immunoexpression. Therefore, the protein might be related to the aetiopathogenesis of the ulcerated oral lesions. © 2011 The Authors. Journal of the European Academy of Dermatology and Venereology © 2011 European Academy of Dermatology and Venereology.

  16. p53 status in stromal fibroblasts modulates tumor growth in an SDF1-dependent manner

    PubMed Central

    Addadi, Yoseph; Moskovits, Neta; Granot, Dorit; Lozano, Guillermina; Carmi, Yaron; Apte, Ron N.; Neeman, Michal; Oren, Moshe

    2010-01-01

    The p53 tumor suppressor exerts a variety of cell-autonomous effects that are aimed to thwart tumor development. In addition, however, there is growing evidence for cell non-autonomous tumor suppressor effects of p53. In the present study, we investigated the impact of stromal p53 on tumor growth. Specifically, we found that ablation of p53 in fibroblasts enabled them to promote more efficiently the growth of tumors initiated by PC3 prostate cancer-derived cells. This stimulatory effect was dependent on the increased expression of the chemokine SDF-1 in the p53-deficient fibroblasts. Notably, fibroblasts harboring mutant p53 protein were more effective than p53-null fibroblasts in promoting tumor growth. The presence of either p53-null or p53-mutant fibroblasts led also to a markedly elevated rate of metastatic spread of the PC3 tumors. These findings implicate p53 in a cell non-autonomous tumor suppressor role within stromal fibroblasts, through suppressing the production of tumor-stimulatory factors by these cells. Moreover, expression of mutant p53 by tumor stroma fibroblasts might exert a gain of function effect, further accelerating tumor development. PMID:20952507

  17. Effects of hydroxyl radical scavenging on cisplatin-induced p53 activation, tubular cell apoptosis and nephrotoxicity

    PubMed Central

    Jiang, Man; Wei, Qingqing; Pabla, Navjotsin; Dong, Guie; Wang, Cong-Yi; Yang, Tianxin; Smith, Sylvia B.; Dong, Zheng

    2009-01-01

    Nephrotoxicity is a major side effect of cisplatin, a widely used cancer therapy drug. Recent work has suggested a role of p53 in renal cell injury by cisplatin. However, the mechanism of p53 activation by cisplatin is unclear. This study determined the possible involvement of oxidative stress in p53 activation under the pathological condition using in vitro and in vivo models. In cultured renal proximal tubular cells, cisplatin at 20 µM induced an early p53 phosphorylation followed by protein accumulation. Cisplatin also induced reactive oxygen species (ROS), among which hydroxyl radicals showed a rapid and drastic accumulation. Dimethylthiourea (DMTU) and N-acetyl-cysteine (NAC) attenuated hydroxyl radical accumulation, and importantly, diminished p53 activation during cisplatin treatment. This was accompanied by the suppression of PUMA-α, a p53-regulated apoptotic gene. Concomitantly, mitochondrial cytochrome crelease and apoptosis were ameliorated. Notably, DMTU and NAC, when added post-cisplatin treatment, were also inhibitory to p53 activation and apoptosis. In C57BL/6 mice, cisplatin at 30 mg/kg induced p53 phosphorylation and protein accumulation, which was also abrogated by DMTU. DMTU also ameliorated tissue damage, tubular cell apoptosis and cisplatin-induced renal failure. Collectively, this study has suggested a role of oxidative stress, particularly hydroxyl radicals, in cisplatin-induced p53 activation, tubular cell apoptosis and nephrotoxicity. PMID:17291459

  18. p53 activation by Ni(II) is a HIF-1α independent response causing caspases 9/3-mediated apoptosis in human lung cells

    SciTech Connect

    Wong, Victor C.; Morse, Jessica L.; Zhitkovich, Anatoly

    2013-06-15

    Hypoxia mimic nickel(II) is a human respiratory carcinogen with a suspected epigenetic mode of action. We examined whether Ni(II) elicits a toxicologically significant activation of the tumor suppressor p53, which is typically associated with genotoxic responses. We found that treatments of H460 human lung epithelial cells with NiCl{sub 2} caused activating phosphorylation at p53-Ser15, accumulation of p53 protein and depletion of its inhibitor MDM4 (HDMX). Confirming the activation of p53, its knockdown suppressed the ability of Ni(II) to upregulate MDM2 and p21 (CDKN1A). Unlike DNA damage, induction of GADD45A by Ni(II) was p53-independent. Ni(II) also increased p53-Ser15 phosphorylation and p21 expression in normal human lung fibroblasts. Although Ni(II)-induced stabilization of HIF-1α occurred earlier, it had no effect on p53 accumulation and Ser15 phosphorylation. Ni(II)-treated H460 cells showed no evidence of necrosis and their apoptosis and clonogenic death were suppressed by p53 knockdown. The apoptotic role of p53 involved a transcription-dependent program triggering the initiator caspase 9 and its downstream executioner caspase 3. Two most prominently upregulated proapoptotic genes by Ni(II) were PUMA and NOXA but only PUMA induction required p53. Knockdown of p53 also led to derepression of antiapoptotic MCL1 in Ni(II)-treated cells. Overall, our results indicate that p53 plays a major role in apoptotic death of human lung cells by Ni(II). Chronic exposure to Ni(II) may promote selection of resistant cells with inactivated p53, providing an explanation for the origin of p53 mutations by this epigenetic carcinogen. - Highlights: • Ni(II) is a strong activator of the transcription factor p53. • Apoptosis is a principal form of death by Ni(II) in human lung epithelial cells. • Ni(II)-activated p53 triggers caspases 9/3-mediated apoptotic program. • NOXA and PUMA are two main proapoptotic genes induced by Ni(II). • HIF-1α and p53 are independent

  19. Anti-Her-2/neu antibody induces apoptosis in Her-2/neu overexpressing breast cancer cells independently from p53 status

    PubMed Central

    Brodowicz, T; Kandioler, D; Tomek, S; Ludwig, C; Rudas, M; Kunstfeld, R; Koestler, W; Hejna, M; Budinsky, A; Wiltschke, C; Zielinski, C C

    2001-01-01

    Anti-Her-2/neu antibody is known to induce apoptosis in HER-2/neu overexpressing breast cancer cells. However, exact regulatory mechanisms mediating and controlling this phenomenon are still unknown. In the present study, we have investigated the effect of anti-Her-2/neu antibody on apoptosis of HER-2/neu overexpressing human breast cancer cell lines SK-BR-3, HTB-24, HTB-25, HTB-27, HTB-128, HTB-130 and HTB-131 in relation to p53 genotype and bcl-2 status. SK-BR-3, HTB-24, HTB-128 and HTB-130 cells exhibited mutant p53, whereas wild type p53 was found in HTB-25, HTB-27 and HTB-131 cells. All seven cell lines weakly expressed bcl-2 protein (10–20%). Anti-Her-2/neu antibody, irrespective of p53 and bcl-2 status, induced apoptosis in all 7 cell lines dose- and time-dependently and correlated with Her-2/neu overexpression. In addition, incubation of cell lines with anti-Her-2/neu antibody did not alter p53 or bcl-2 expression. Anti-HER-2/neu antibody did not induce apoptosis in HER-2/neu negative HBL-100 and HTB-132 cell lines. Our results indicate that within the panel of tested breast cancer cell lines, anti-Her-2/neu antibody-induced apoptosis was independent from the presence of intact p53. © 2001 Cancer Research Compaign http://www.bjcancer.com PMID:11742500

  20. Porcine parvovirus infection induces apoptosis in PK-15 cells through activation of p53 and mitochondria-mediated pathway

    SciTech Connect

    Zhang, Hongling; Huang, Yong; Du, Qian; Luo, Xiaomao; Zhang, Liang; Zhao, Xiaomin; Tong, Dewen

    2015-01-09

    Highlights: • PPV reduces PK-15 cells viability by inducing apoptosis. • PPV infection induces apoptosis through mitochondria-mediated pathway. • PPV infection activates p53 to regulate the mitochondria apoptotic signaling. - Abstract: Porcine parvovirus (PPV) infection has been reported to induce the cytopathic effects (CPE) in some special host cells and contribute the occurrence of porcine parvovirus disease, but the molecular mechanisms underlying PPV-induced CPE are not clear. In this study, we investigated the morphological and molecular changes of porcine kidney cell line (PK-15 cells) infected with PPV. The results showed that PPV infection inhibited the viability of PK-15 cells in a time and concentration dependent manner. PPV infection induced typical apoptotic features including chromatin condensation, apoptotic body formation, nuclear fragmentation, and Annexin V-binding activity. Further studies showed that Bax was increased and translocated to mitochondria, whereas Bcl-2 was decreased in PPV-infected cells, which caused mitochondrial outer-membrane permeabilization, resulting in the release of mitochondrial cytochrome c, followed by caspase-9 and caspase-3 activation. However, the expression of Fas and Fas ligand (FasL) did not appear significant changes in the process of PPV-induced apoptosis. Moreover, PPV infection activated p53 signaling, which was involved in the activation of apoptotic signaling induced by PPV infection via regulation of Bax and Bcl-2. Taken together, our results demonstrated that PPV infection induced apoptosis in PK-15 cells through activation of p53 and mitochondria-mediated apoptosis pathway. This study may contribute to shed light on the molecular pathogenesis of PPV infection.

  1. UVB-mediated activation of p38 mitogen-activated protein kinase enhances resistance of normal human keratinocytes to apoptosis by stabilizing cytoplasmic p53.

    PubMed

    Chouinard, Nadine; Valerie, Kristoffer; Rouabhia, Mahmoud; Huot, Jacques

    2002-07-01

    Human keratinocytes respond to UV rays by developing a fast adaptive response that contributes to maintaining their functions and survival. We investigated the role of the mitogen-activated protein kinase pathways in transducing the UV signals in normal human keratinocytes. We found that UVA, UVB or UVC induced a marked and persistent activation of p38, whereas c-Jun N-terminal kinase or extracellular signal-regulated kinase were less or not activated respectively. Inhibition of p38 activity by expression of a dominant-negative mutant of p38 or with SB203580 impaired cell viability and led to an increase in UVB-induced apoptosis. This sensitization to apoptosis was independent of caspase activities. Inhibition of p38 did not sensitize transformed HaCaT keratinocytes to UVB-induced apoptosis. In normal keratinocytes, expression of a dominant-negative mutant of p53 increased UVB-induced cell death, pointing to a role for p53. In these cells, UVB triggered a p38-dependent phosphorylation of p53 on Ser-15. This phosphorylation was associated with an SB203580-sensitive accumulation of p53, even in the presence of a serine phosphatase inhibitor. Accumulated p53 was localized mainly in the cytoplasm, independently of CRM1 nuclear export. In HaCaT cells, p53 was localized exclusively in the nucleus and its distribution and level were not affected by UVB or p38 inhibition. However, UVB induced an SB203580-insensitive phosphorylation on Ser-15 of mutated p53. Overall, our results suggest that, in normal human keratinocytes, protection against UVB depends on p38-mediated phosphorylation and stabilization of p53 and is tightly associated with the cytoplasmic sequestration of wild-type p53. We conclude that the p38/p53 pathway plays a key role in the adaptive response of normal human keratinocytes against UV stress.

  2. P53-Mediated Rapid Induction of Apoptosis Conveys Resistance to Viral Infection in Drosophila melanogaster

    PubMed Central

    Liu, Bo; Behura, Susanta K.; Clem, Rollie J.; Schneemann, Anette; Becnel, James; Severson, David W.; Zhou, Lei

    2013-01-01

    Arthropod-borne pathogens account for millions of deaths each year. Understanding the genetic mechanisms controlling vector susceptibility to pathogens has profound implications for developing novel strategies for controlling insect-transmitted infectious diseases. The fact that many viruses carry genes that have anti-apoptotic activity has long led to the hypothesis that induction of apoptosis could be a fundamental innate immune response. However, the cellular mechanisms mediating the induction of apoptosis following viral infection remained enigmatic, which has prevented experimental verification of the functional significance of apoptosis in limiting viral infection in insects. In addition, studies with cultured insect cells have shown that there is sometimes a lack of apoptosis, or the pro-apoptotic response happens relatively late, thus casting doubt on the functional significance of apoptosis as an innate immunity. Using in vivo mosquito models and the native route of infection, we found that there is a rapid induction of reaper-like pro-apoptotic genes within a few hours following exposure to DNA or RNA viruses. Recapitulating a similar response in Drosophila, we found that this rapid induction of apoptosis requires the function of P53 and is mediated by a stress–responsive regulatory region upstream of reaper. More importantly, we showed that the rapid induction of apoptosis is responsible for preventing the expression of viral genes and blocking the infection. Genetic changes influencing this rapid induction of reaper-like pro-apoptotic genes led to significant differences in susceptibility to viral infection. PMID:23408884

  3. Distinct patterns of cleavage and translocation of cell cycle control proteins in CD95-induced and p53-induced apoptosis.

    PubMed Central

    Park, Weon Seo; Jung, Kyeong Cheon; Chung, Doo Hyun; Nam, Woo-Dong; Choi, Won Jin; Bae, Youngmee

    2003-01-01

    Apoptotic cell death induced by p53 occurs at a late G1 cell cycle checkpoint termed the restriction (R) point, and it has been proposed that p53-induced apoptosis causes upregulation of CD95. However, as cells with defective in CD95 signaling pathway are still sensitive to p53-induced apoptosis, CD95 cannot be the sole factor resulting in apoptosis. In addition, unlike p53-induced apoptosis, the relationship between CD95-mediated apoptosis and the cell cycle is not clearly understood. It would therefore be worth investigating whether CD95-mediated cell death is pertinent with p53-induced apoptosis in view of cell cycle related molecules. In this report, biochemical analysis showed that etoposide-induced apoptosis caused the induction and the nuclear translocation of effector molecules involved in G1 cell cycle checkpoint. However, there was no such translocation in the case of CD95-mediated death. Thus, although both types of apoptosis involved caspase activation, the cell cycle related proteins responded differently. This argues against the idea that p53-induced apoptosis occurs through the induction of CD95/CD95L expression. PMID:12923319

  4. A Novel Sirtuin 2 (SIRT2) Inhibitor with p53-dependent Pro-apoptotic Activity in Non-small Cell Lung Cancer*

    PubMed Central

    Hoffmann, Gesine; Breitenbücher, Frank; Schuler, Martin; Ehrenhofer-Murray, Ann E.

    2014-01-01

    Sirtuin 2 (SIRT2) is an NAD+-dependent protein deacetylase whose targets include histone H4 lysine 16, p53, and α-tubulin. Because deacetylation of p53 regulates its effect on apoptosis, pharmacological inhibition of SIRT2-dependent p53 deacetylation is of great therapeutic interest for the treatment of cancer. Here, we have identified two structurally related compounds, AEM1 and AEM2, which are selective inhibitors of SIRT2 (IC50 values of 18.5 and 3.8 μm, respectively), but show only weak effects on other sirtuins such as SIRT1, SIRT3, and yeast Sir2. Interestingly, both compounds sensitized non-small cell lung cancer cell lines toward the induction of apoptosis by the DNA-damaging agent etoposide. Importantly, this sensitization was dependent on the presence of functional p53, thus establishing a link between SIRT2 inhibition by these compounds and p53 activation. Further, treatment with AEM1 and AEM2 led to elevated levels of p53 acetylation and to increased expression of CDKN1A, which encodes the cell cycle regulator p21WAF1, as well as the pro-apoptotic genes PUMA and NOXA, three transcriptional targets of p53. Altogether, our data suggest that inhibition of SIRT2 by these compounds causes increased activation of p53 by decreasing SIRT2-dependent p53 deacetylation. These compounds thus provide a good opportunity for lead optimization and drug development to target p53-proficient cancers. PMID:24379401

  5. Effect of poly(ADP-ribose)polymerase and DNA topoisomerase I inhibitors on the p53/p63-dependent survival of carcinoma cells.

    PubMed

    Montariello, Daniela; Troiano, Annaelena; Di Girolamo, Daniela; Beneke, Sascha; Calabrò, Viola; Quesada, Piera

    2015-04-01

    Depending on their genetic background (p53(wt) versus p53(null)), carcinoma cells are more or less sensitive to drug-induced cell cycle arrest and/or apoptosis. Among the members of the p53 family, p63 is characterized by two N-terminal isoforms, TAp63 and ΔNp63. TAp63 isoform has p53-like functions, while ΔNp63 acts as a dominant negative inhibitor of p53. We have previously published that TAp63 is involved in poly(ADP-ribose)polymerase-1 (PARP-1) signaling of DNA damage deriving from DNA topoisomerase I (TOP I) inhibition in carcinoma cells. In the present study, we treated MCF7 breast carcinoma cells (p53(+)/ΔNp63(-)) or SCC022 (p53(-)/ΔNp63(+)) squamous carcinoma cells with the TOP I inhibitor topotecan (TPT) and the PJ34 PARP inhibitor, to compare their effects in the two different cell contexts. In MCF7 cells, we found that PJ34 addition reverts TPT-dependent PARP-1 auto-modification and triggers caspase-dependent PARP-1 proteolysis. Moreover, TPT as single agent stimulates p53(ser15) phosphorylation, p53 PARylation and occupancy of the p21WAF promoter by p53 resulting in an increase of p21WAF expression. Interestingly, PJ34 in combination with TPT enhances p53 occupancy at the BAX promoter and is associated with increased BAX protein level. In SCC022 cells, instead, TPT+PJ34 combined treatment reduces the level of the anti-apoptotic ΔNp63α protein without inducing apoptosis. Remarkably, in such cells, either exogenous p53 or TAp63 can rescue the apoptotic program in response to the treatment. All together our results suggest that in cancer cells PARP inhibitor(s) can operate in the choice between growth arrest and apoptosis by modulating p53 family-dependent signal.

  6. Berberine induces mitochondrial apoptosis of EBV-transformed B cells through p53-mediated regulation of XAF1 and GADD45α.

    PubMed

    Park, Ga Bin; Park, Sang Hyun; Kim, Daejin; Kim, Yeong Seok; Yoon, Sung Ho; Hur, Dae Young

    2016-07-01

    Berberine exhibits antiproliferative or cytotoxic effects against various cancers. ROS and wild-type p53 play a critical role in berberine-induced cytotoxic effects. In this study, we investigated the correlation between XAF1 and functional p53 in EBV-transformed B cells or cancerous B cells after treatment with berberine. Berberine decreased cell viability and induced apoptosis through a mitochondria-dependent pathway in EBV-transformed B cells and cancerous B cells, but not in normal peripheral blood mononuclear cells. Activated p53 and its downstream targets XAF1 and GADD45α interacted with PUMA, Bax, and Bim in mitochondria after treatment with berberine. Blocking phosphorylation of p38/JNK MAPK and treatment with PFT-α, a selective p53 inhibitor, effectively prevented apoptosis and the upregulation of phosphorylated p53, XAF1, and GADD45α. NAC, a ROS scavenger, also suppressed berberine-induced mitochondria disruption and the whole apoptotic process via restoration of p53-related proteins and proapoptotic Bcl-2 family proteins. Taken together, our results suggest that ROS generation might be a predisposing event in berberine-induced mitochondrial apoptosis in EBV-transformed B cells through the upregulation of XAF1 and GADD45α expression by MAPK and functional p53.

  7. CSF1 Is a Novel p53 Target Gene Whose Protein Product Functions in a Feed-Forward Manner to Suppress Apoptosis and Enhance p53-Mediated Growth Arrest

    PubMed Central

    Azzam, Gregory; Wang, Xuting; Bell, Douglas; Murphy, Maureen E.

    2013-01-01

    The p53 tumor suppressor gene has a common polymorphism at codon 72 that alters its function. We previously reported that the proline 72 polymorphic variant of p53 (P72) demonstrates increased ability to transactivate a subset of genes, relative to arginine 72 (R72); one of these genes is macrophage colony stimulating factor (CSF1). At present, the mechanism(s) underlying the increased transcriptional activity of P72 toward genes like CSF1 have not been completely elucidated. Additionally, the consequences of increased transcription of genes like CSF1 by the P72 variant to the downstream p53 pathway are unknown. In this report, we address these issues. We show that the CSF1 gene contains a conserved binding site for p53, and interestingly that the P72 variant shows increased ability to bind to this site. Moreover, we show that increased CSF1/CSF1R signaling in P72 cells feeds back on the p53 pathway to enhance p53 phosphorylation, levels, and transactivation of target genes, particularly the cyclin-dependent kinase inhibitor p21 (CDKN1A). This leads to an increase in p53-mediated growth arrest, along with a concomitant decrease in apoptosis. Notably, the CSF1/CSF1R signaling axis is overexpressed in several epithelial cancers, and there is clinical evidence that this pathway plays a role in radio-resistance of some cancers. We show that cells expressing CSF1 and CSF1R are indeed radio-resistant, and further, that this effect requires p53. These combined data are the first to implicate the CSF1/CSF1R pathway in the decision between p53-mediated growth arrest and apoptosis. They are also the first to highlight a cytokine as influential in cell fate determined by p53 in epithelial cells. Finally, these data may explain the association of the P72 variant and the CSF1/CSF1R pathway with increased senescence and radio-resistance in some epithelial tumor types. PMID:24019961

  8. Heat shock proteins and p53 play a critical role in K+ channel-mediated tumor cell proliferation and apoptosis.

    PubMed

    Han, Xiaobing; Wang, Fang; Yao, Weixing; Xing, Hui; Weng, Danhui; Song, Xiaohong; Chen, Gang; Xi, Ling; Zhu, Tao; Zhou, Jianfeng; Xu, Gang; Wang, Shixuan; Meng, Li; Iadecola, Costantino; Wang, Gang; Ma, Ding

    2007-10-01

    Plasma membrane potassium (K+) channels are required for tumor cell proliferation and apoptosis. However, the signal transduction mechanisms underlying K+ channel-dependent tumor cell proliferation or apoptosis remains elusive. Using HeLa and A2780 cells as study models, we tested the hypothesis that apoptotic proteins are linked with K+ channel-dependent tumor cell cycle and apoptosis. The patch-clamping study using the whole-cell mode revealed two components of voltage-gated outward K+ currents: one is sensitive to either tetraethylammonium (TEA) or tetrandrine (Tet), a maxi-conductance Ca2+-activated K+ (BK) channel blocker, and the other is sensitive to 4-aminopyridine (4-AP), a delayed rectifier K+ channel blocker. MTT and flow cytometry assays showed that TEA, Tet, or iberiotoxin (Ibtx), a selective BK channel blocker, inhibited HeLa and A2780 cell proliferation in a dose-dependent manner with G1 phase arrest. Pretreatment with TEA or Tet also induced apoptosis in HeLa and A2780 cells. However, glibenclamide (Gli), an ATP-sensitive K+ channel blocker, did not influence K+ currents, proliferation or apoptosis. Western blot analyses showed that while pretreatment of TEA and Tet produced an increase in expressions of p53, p21, and Bax, pretreatment of these two agents led to a decrease in expressions of heat shock protein (hsp)90alpha, hsp90beta, and hsp70. Our results indicate that the blockade of BK channels results in tumor cell apoptosis and cycle arrest at G1 phase, and the transduction pathway underlying the anti-proliferative effects is linked to the increased expression of apoptotic protein p53 and the decreased expression of its chaperone proteins hsp.

  9. Activation of p53 by Nutlin-3a, an antagonist of MDM2, induces apoptosis and cellular senescence in adult T-cell leukemia cells.

    PubMed

    Hasegawa, H; Yamada, Y; Iha, H; Tsukasaki, K; Nagai, K; Atogami, S; Sugahara, K; Tsuruda, K; Ishizaki, A; Kamihira, S

    2009-11-01

    It has been reported that the induction of cellular senescence through p53 activation is an effective strategy in tumor regression. Unfortunately, however, tumors including adult T-cell leukemia/lymphoma (ATL) have disadvantages such as p53 mutations and a lack of p16(INK4a) and/or p14(ARF). In this study we characterized Nutlin-3a-induced cell death in 16 leukemia/lymphoma cell lines. Eight cell lines, including six ATL-related cell lines, had wild-type p53 and Nutlin-3a-activated p53, and the cell lines underwent apoptosis or cell-cycle arrest, whereas eight cell lines with mutated p53 were resistant. Interestingly, senescence-associated-beta-galactosidase (SA-beta-gal) staining revealed that only ATL-related cell lines with wild-type p53 showed cellular senescence, although they lack both p16(INK4a) and p14(ARF). These results indicate that cellular senescence is an important event in p53-dependent cell death in ATL cells and is inducible without p16(INK4a) and p14(ARF). Furthermore, knockdown of Tp53-induced glycolysis and apoptosis regulator (TIGAR), a novel target gene of p53, by small interfering RNA(siRNA) indicated its important role in the induction of cellular senescence. As many patients with ATL carry wild-type p53, our study suggests that p53 activation by Nutlin-3a is a promising strategy in ATL. We also found synergism with a combination of Nutlin-3a and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), suggesting the application of Nutlin-3a-based therapy to be broader than expected.

  10. p53 dependent Nestin regulation links tumor suppression to cellular plasticity in liver cancer

    PubMed Central

    Tschaharganeh, Darjus F; Xue, Wen; Calvisi, Diego F; Evert, Matthias; Michurina, Tatyana V; Dow, Lukas E; Banito, Ana; Katz, Sarah F; Kastenhuber, Edward R; Weissmueller, Susann; Huang, Chun-Hao; Lechel, Andre; Andersen, Jesper B; Capper, David; Zender, Lars; Longerich, Thomas; Enikolopov, Grigori; Lowe, Scott W

    2014-01-01

    Summary The p53 tumor suppressor coordinates a series of anti-proliferative responses that restrict the expansion of malignant cells and, as a consequence, p53 is lost or mutated in the majority of human cancers. Here, we show that p53 restricts expression of the stem and progenitor cell-associated protein nestin in an Sp1/3 transcription factor-dependent manner and that nestin is required for tumor initiation in vivo. Moreover, loss of p53 facilitates dedifferentiation of mature hepatocytes into nestin-positive progenitor-like cells, which are poised to differentiate into hepatocellular carcinomas (HCCs) or cholangiocarcinomas (CCs) in response to lineage-specific mutations that target Wnt and Notch signaling, respectively. Many human HCCs and CCs show elevated nestin expression, which correlates with p53 loss of function and is associated with decreased patient survival. Therefore, transcriptional repression of Nestin by p53 restricts cellular plasticity and tumorigenesis in liver cancer. PMID:25083869

  11. Honokiol induces cell cycle arrest and apoptosis via p53 activation in H4 human neuroglioma cells.

    PubMed

    Guo, Yun-Bao; Bao, Xin-Jie; Xu, Song-Bai; Zhang, Xing-Dong; Liu, Hai-Yan

    2015-01-01

    To investigate the signal pathway of honokiol-induced apoptosis in H4 human neuroglioma cells and to evaluate whether p53 signaling and cell cycle arrest were involved in honokiol-treated H4 human neuroglioma cells. The cell viability was detected by the CCK8 assay. The cell apoptosis was assessed by annexin V-PI double-labeling staining and hoechst 33342 staining. The protein expression of cell cycle regulators and tumor suppressors were analyzed by western blotting. Treatment of H4 human neuroglioma cells with honokiol induced cell death in a dose-and time-dependent manner by using CCK8 assay. Consistent with the CCK8 assay, the flow cytometry results showed that the proportion of the apoptosis cells increased after honokiol when compared with untreated group. Moreover, H4 human neuroglioma cells exposed to honokiol, resulted in an accumulation of cells in S and G2/M phase. Apoptotic bodies were clearly observed in human neuroglioma cells when treated with honokiol and then stained with Hoechst 33342. The expression of Cyclin B1, CDC2 and cdc25C were downregulated, however, the expression of p-CDC2 and p-cdc25c was significantly upregulated when the neuroglioma cells were exposed to honokiol. Moreover, p53, p21 and Bax/Bcl-2 were significantly upregulated by honokiol treatment. These results confirmed that honokiol could induce apoptosis in human neuroglioma cells, the underlying molecular mechanisms, at least partially, through activation p53 signaling and induction of cell cycle arrest.

  12. The p53-SET Interplays Reveal A New Mode of Acetylation-dependent Regulation

    PubMed Central

    Lasso, Gorka; Jiang, Le; Leng, Wenchuan; Zhu, Wei-Guo; Qin, Jun; Honig, Barry; Gu, Wei

    2016-01-01

    Summary Although lysine acetylation is now recognized as a general protein modification for both histones and non-histone proteins1-3, the mechanisms of acetylation mediated actions are not completely understood. Acetylation of the C-terminal domain (CTD) of p53 was the first example for non-histone protein acetylation4. Yet the precise role of the CTD acetylation remains elusive. Lysine acetylation often creates binding sites for bromodomain-containing “reader” proteins5,6; surprisingly, in a proteomic screen, we identified SET as a major cellular factor whose binding with p53 is totally dependent on the CTD acetylation status. SET profoundly inhibits p53 transcriptional activity in unstressed cells but SET-mediated repression is completely abolished by stress-induced p53 CTD acetylation. Moreover, loss of the interaction with SET activates p53, resulting in tumor regression in mouse xenograft models. Notably, the acidic domain of SET acts as a “reader” for unacetylated CTD of p53 and this mechanism of acetylation-dependent regulation is widespread in nature. For example, p53 acetylation also modulates its interactions with similar acidic domains found in other p53 regulators including VPRBP, DAXX and PELP1 (refs. 7-9), and computational analysis of the proteome identified numerous proteins with the potential to serve as the acidic domain readers and lysine-rich ligands. Unlike bromodomain readers, which preferentially bind the acetylated forms of their cognate ligands, the acidic domain readers specifically recognize the unacetylated forms of their ligands. Finally, the acetylation-dependent regulation of p53 was further validated in vivo by using a knockin mouse model expressing an acetylation-mimicking form of p53. These results reveal that the acidic domain-containing factors act as a new class of acetylation-dependent regulators by targeting p53 and potentially, beyond. PMID:27626385

  13. Bim directly antagonizes Bcl-xl in doxorubicin-induced prostate cancer cell apoptosis independently of p53

    PubMed Central

    Yang, Min-Chi; Lin, Ru-Wei; Huang, Shih-Bo; Huang, Shin-Yuan; Chen, Wen-Jie; Wang, Shiaw; Hong, Yi-Ren; Wang, Chihuei

    2016-01-01

    ABSTRACT Doxorubicin and other anthracycline compounds exert their anti-cancer effects by causing DNA damage and initiating cell cycle arrest in cancer cells, followed by apoptosis. DNA damage generally activates a p53-mediated pathway to initiate apoptosis by increasing the level of the BH3-only protein, Puma. However, p53-mediated apoptosis in response to DNA damage has not yet been validated in prostate cancers. In the current study, we used LNCaP and PC3 prostate cancer cells, representing wild type p53 and a p53-null model, to determine if DNA damage activates p53-mediated apoptosis in prostate cancers. Our results revealed that PC3 cells were 4 to 8-fold less sensitive than LNCaP cells to doxorubicin-inuced apoptosis. We proved that the differential response of LNCaP and PC3 to doxorubicin was p53-independent by introducing wild-type or dominant negative p53 into PC3 or LNCaP cells, respectively. By comparing several apoptosis-related proteins in both cell lines, we found that Bcl-xl proteins were much more abundant in PC3 cells than in LNCaP cells. We further demonstrated that Bcl-xl protects LNCaP and PC3 cells from doxorubicin-induced apoptosis by using ABT-263, an inhibitor of Bcl-xl, as a single agent or in combination with doxorubicin to treat LNCaP or PC3 cells. Bcl-xl rather than p53, likely contributes to the differential response of LNCaP and PC3 to doxorubicin in apoptosis. Finally, co-immunoprecipitation and siRNA analysis revealed that a BH3-only protein, Bim, is involved in doxorubicin-induced apoptosis by directly counteracting Bcl-xl. PMID:26694174

  14. Bim directly antagonizes Bcl-xl in doxorubicin-induced prostate cancer cell apoptosis independently of p53.

    PubMed

    Yang, Min-Chi; Lin, Ru-Wei; Huang, Shih-Bo; Huang, Shin-Yuan; Chen, Wen-Jie; Wang, Shiaw; Hong, Yi-Ren; Wang, Chihuei

    2016-01-01

    Doxorubicin and other anthracycline compounds exert their anti-cancer effects by causing DNA damage and initiating cell cycle arrest in cancer cells, followed by apoptosis. DNA damage generally activates a p53-mediated pathway to initiate apoptosis by increasing the level of the BH3-only protein, Puma. However, p53-mediated apoptosis in response to DNA damage has not yet been validated in prostate cancers. In the current study, we used LNCaP and PC3 prostate cancer cells, representing wild type p53 and a p53-null model, to determine if DNA damage activates p53-mediated apoptosis in prostate cancers. Our results revealed that PC3 cells were 4 to 8-fold less sensitive than LNCaP cells to doxorubicin-inuced apoptosis. We proved that the differential response of LNCaP and PC3 to doxorubicin was p53-independent by introducing wild-type or dominant negative p53 into PC3 or LNCaP cells, respectively. By comparing several apoptosis-related proteins in both cell lines, we found that Bcl-xl proteins were much more abundant in PC3 cells than in LNCaP cells. We further demonstrated that Bcl-xl protects LNCaP and PC3 cells from doxorubicin-induced apoptosis by using ABT-263, an inhibitor of Bcl-xl, as a single agent or in combination with doxorubicin to treat LNCaP or PC3 cells. Bcl-xl rather than p53, likely contributes to the differential response of LNCaP and PC3 to doxorubicin in apoptosis. Finally, co-immunoprecipitation and siRNA analysis revealed that a BH3-only protein, Bim, is involved in doxorubicin-induced apoptosis by directly counteracting Bcl-xl.

  15. p53, cellular proliferation, and apoptosis-related factors in thymic neuroendocrine tumors.

    PubMed

    Gal, Anthony A; Sheppard, Mary N; Nolen, John D L; Cohen, Cynthia

    2004-01-01

    Thymic neuroendocrine tumors are biologically aggressive neoplasms with extensive local invasion and high mortality. Although various markers of cellular proliferation and apoptosis have correlated with degrees of tumor differentiation in pulmonary neuroendocrine neoplasms, they have not been systematically studied in thymic neuroendocrine tumors. We immunostained 21 cases of thymic neuroendocrine tumors for p53, MIB-1, and the apoptosis-related markers Bcl-2, Bcl-x, and Bax. By histological classification the cases were low-grade (nine cases), intermediate-grade (eight cases), and high-grade (four cases) thymic neuroendocrine tumors. p53 was expressed in five cases: 1/9 low grade, 3/8 intermediate grade, and 2/4 high grade. The mean cellular proliferation (MIB-1) was 7.1% (range 2-12%) in low-grade thymic neuroendocrine tumors, 6.1% (range 2-15%) in intermediate-grade thymic neuroendocrine tumors, and 34.2% (range 2-80%) in high-grade thymic neuroendocrine tumors. Bcl-2 was expressed in 16 cases: 7/9 low grade, 5/8 intermediate grade, and 4/4 high grade. Bcl-x was expressed in 16 cases: 7/9 low grade, 6/8 intermediate grade, and 3/4 high grade. Bax was expressed in 13 cases: 5/9 low grade, 4/8 intermediate grade, and 4/4 high grade. The presence of mutant p53 in the tumor was associated with a statistically significant decreased mean survival (P<0.05). In contrast, either by positive or negative staining or by the score technique (staining intensity x percentage of cells staining), the presence of Bcl-x was associated with an increased mean survival (P<0.05). Finally, a Bcl-x : Bax ratio >or=1 was also associated with an increased mean survival, as compared to a Bcl-x : Bax ratio >or=1 (P<0.05). Our study shows that p53 expression and certain apoptosis markers correlate with survival. The expression of these markers may account for differences in biological behavior.

  16. Heat stress induces apoptosis through transcription-independent p53-mediated mitochondrial pathways in human umbilical vein endothelial cell.

    PubMed

    Gu, Z T; Wang, H; Li, L; Liu, Y S; Deng, X B; Huo, S F; Yuan, F F; Liu, Z F; Tong, H S; Su, L

    2014-03-26

    Cells apoptosis induced by intense heat stress is the prominent feature of heat-related illness. However, little is known about the biological effects of heat stress on cells apoptosis. Herein, we presented evidence that intense heat stress could induce early apoptosis of HUVEC cells through activating mitochondrial pathway with changes in mitochondrial membrane potential(ΔΨm), release of cytochrome c, and activation of caspase-9 and -3. We further revealed that p53 played a crucial role in heat stress-induced early apoptosis, with p53 protein rapidly translocated into mitochondria. Using pifithrin-α(PFT), a p53's mitochondrial translocation inhibitor, we found that pretreated with PFT, heat stress induced mitochondrial p53 translocation was significantly suppressed, accompanied by a significant alleviation in the loss of ΔΨm, cytochrome c release and caspase-9 activation. Furthermore, we also found that generation of reactive oxygen species (ROS) was a critical mediator in heat stress-induced apoptosis. In addition, the antioxidant MnTMPyP significantly decreased the heat stress-induced p53's mitochondrial translocation, followed by the loss of ΔΨm, cytochrome c release, caspase-9 activation and heat stress-mediated apoptosis. Conclusively, these findings indicate the contribution of the transcription-independent mitochondrial p53 pathway to early apoptosis in HUVEC cells induced by oxidative stress in response to intense heat stress.

  17. Aerobic glycolysis suppresses p53 activity to provide selective protection from apoptosis upon loss of growth signals or inhibition of BCR-Abl

    PubMed Central

    Mason, Emily F.; Zhao, Yuxing; Goraksha-Hicks, Pankuri; Coloff, Jonathan L.; Gannon, Hugh; Jones, Stephen N.; Rathmell, Jeffrey C.

    2010-01-01

    Unlike the growth factor-dependence of normal cells, cancer cells can maintain growth factor-independent glycolysis and survival through expression of oncogenic kinases, such as BCR-Abl. While targeted kinase inhibition can promote cancer cell death, therapeutic resistance develops frequently and further mechanistic understanding is needed. Cell metabolism may be central to this cell death pathway, as we have shown that growth factor deprivation leads to decreased glycolysis that promotes apoptosis via p53 activation and induction of the pro-apoptotic protein Puma. Here, we extend these findings to demonstrate that elevated glucose metabolism, characteristic of cancer cells, can suppress PKCδ-dependent p53 activation to maintain cell survival after growth factor withdrawal. In contrast, DNA damage-induced p53 activation was PKCδ-independent and was not metabolically sensitive. Both stresses required p53 serine 18 phosphorylation for maximal activity but led to unique patterns of p53 target gene expression, demonstrating distinct activation and response pathways for p53 that were differentially regulated by metabolism. Consistent with oncogenic kinases acting to replace growth factors, treatment of BCR-Abl-expressing cells with the kinase inhibitor imatinib led to reduced metabolism and p53- and Puma-dependent cell death. Accordingly, maintenance of glucose uptake inhibited p53 activation and promoted imatinib resistance. Furthermore, inhibition of glycolysis enhanced imatinib sensitivity in BCR-Abl-expressing cells with wild type p53 but had little effect on p53 null cells. These data demonstrate that distinct pathways regulate p53 after DNA damage and metabolic stress and that inhibiting glucose metabolism may enhance the efficacy of and overcome resistance to targeted molecular cancer therapies. PMID:20876800

  18. ASPP1/2 regulate p53-dependent death of retinal ganglion cells through PUMA and Fas/CD95 activation in vivo.

    PubMed

    Wilson, Ariel M; Morquette, Barbara; Abdouh, Mohamed; Unsain, Nicolás; Barker, Philip A; Feinstein, Elena; Bernier, Gilbert; Di Polo, Adriana

    2013-01-30

    The transcription factor p53 mediates neuronal death in a variety of stress-related and neurodegenerative conditions. The proapoptotic activity of p53 is tightly regulated by the apoptosis-stimulating proteins of p53 (ASPP) family members: ASPP1 and ASPP2. However, whether ASPP1/2 play a role in the regulation of p53-dependent neuronal death in the CNS is currently unknown. To address this, we asked whether ASPP1/2 contribute to the death of retinal ganglion cells (RGCs) using in vivo models of acute optic nerve damage in mice and rats. Here, we show that p53 is activated in RGCs soon after injury and that axotomy-induced RGC death is attenuated in p53 heterozygote and null mice. We demonstrate that ASPP1/2 proteins are abundantly expressed by injured RGCs, and that short interfering (si)RNA-based ASPP1 or ASPP2 knockdown promotes robust RGC survival. Comparative gene expression analysis revealed that siASPP-mediated downregulation of p53-upregulated-modulator-of-apoptosis (PUMA), Fas/CD95, and Noxa depends on p53 transcriptional activity. Furthermore, siRNA against PUMA or Fas/CD95 confers neuroprotection, demonstrating a functional role for these p53 targets in RGC death. Our study demonstrates a novel role for ASPP1 and ASPP2 in the death of RGCs and provides evidence that blockade of the ASPP-p53 pathway is beneficial for central neuron survival after axonal injury.

  19. Aurora-A induces cell survival and chemoresistance by activation of Akt through a p53-dependent manner in ovarian cancer cells.

    PubMed

    Yang, Hua; He, Lili; Kruk, Patricia; Nicosia, Santo V; Cheng, Jin Q

    2006-11-15

    Aurora-A is frequently altered in epithelial malignancies. Overexpressing Aurora-A induces centrosome amplification and G2/M cell cycle progression. We have previously shown elevated level of Aurora-A in ovarian cancer and activation of telomerase by Aurora-A in human mammary and ovarian epithelia. Here we report that Aurora-A protects ovarian cancer cells from apoptosis induced by chemotherapeutic agent and activates Akt pathway in a p53-dependent manner. Ectopic expression of Aurora-A renders cells resistant to cisplatin (CDDP), etoposide and paclitaxel-induced apoptosis and stimulates Akt1 and Akt2 activity in wild-type p53 but not p53-null ovarian cancer cells. Aurora-A inhibits cytochrome C release and Bax conformational change induced by CDDP. Knockdown of Aurora-A by RNAi sensitizes cells to CDDP-induced apoptosis and decreases phospho-Akt level in wild-type p53 cells. Reintroduction of p53 decreases Akt1 and Akt2 activation and restores CDDP sensitivity in p53-null but not p53-null-Aurora-A cells. Inhibition of Akt by small molecule inhibitor, API-2, overcomes the effects of Aurora-A-on cell survival and Bax mitochondrial translocation. Taken collectively, these data indicate that Aurora-A activates Akt and induces chemoresistance in a p53-dependent manner and that inhibition of Akt may be an effective means of overcoming Aurora-A-associated chemoresistance in ovarian cancer cells expressing wild-type p53.

  20. Cell Context Dependent p53 Genome-Wide Binding Patterns and Enrichment at Repeats

    DOE PAGES

    Botcheva, Krassimira; McCorkle, Sean R.

    2014-11-21

    The p53 ability to elicit stress specific and cell type specific responses is well recognized, but how that specificity is established remains to be defined. Whether upon activation p53 binds to its genomic targets in a cell type and stress type dependent manner is still an open question. Here we show that the p53 binding to the human genome is selective and cell context-dependent. We mapped the genomic binding sites for the endogenous wild type p53 protein in the human cancer cell line HCT116 and compared them to those we previously determined in the normal cell line IMR90. We reportmore » distinct p53 genome-wide binding landscapes in two different cell lines, analyzed under the same treatment and experimental conditions, using the same ChIP-seq approach. This is evidence for cell context dependent p53 genomic binding. The observed differences affect the p53 binding sites distribution with respect to major genomic and epigenomic elements (promoter regions, CpG islands and repeats). We correlated the high-confidence p53 ChIP-seq peaks positions with the annotated human repeats (UCSC Human Genome Browser) and observed both common and cell line specific trends. In HCT116, the p53 binding was specifically enriched at LINE repeats, compared to IMR90 cells. The p53 genome-wide binding patterns in HCT116 and IMR90 likely reflect the different epigenetic landscapes in these two cell lines, resulting from cancer-associated changes (accumulated in HCT116) superimposed on tissue specific differences (HCT116 has epithelial, while IMR90 has mesenchymal origin). In conclusion, our data support the model for p53 binding to the human genome in a highly selective manner, mobilizing distinct sets of genes, contributing to distinct pathways.« less

  1. Cell Context Dependent p53 Genome-Wide Binding Patterns and Enrichment at Repeats

    SciTech Connect

    Botcheva, Krassimira; McCorkle, Sean R.

    2014-11-21

    The p53 ability to elicit stress specific and cell type specific responses is well recognized, but how that specificity is established remains to be defined. Whether upon activation p53 binds to its genomic targets in a cell type and stress type dependent manner is still an open question. Here we show that the p53 binding to the human genome is selective and cell context-dependent. We mapped the genomic binding sites for the endogenous wild type p53 protein in the human cancer cell line HCT116 and compared them to those we previously determined in the normal cell line IMR90. We report distinct p53 genome-wide binding landscapes in two different cell lines, analyzed under the same treatment and experimental conditions, using the same ChIP-seq approach. This is evidence for cell context dependent p53 genomic binding. The observed differences affect the p53 binding sites distribution with respect to major genomic and epigenomic elements (promoter regions, CpG islands and repeats). We correlated the high-confidence p53 ChIP-seq peaks positions with the annotated human repeats (UCSC Human Genome Browser) and observed both common and cell line specific trends. In HCT116, the p53 binding was specifically enriched at LINE repeats, compared to IMR90 cells. The p53 genome-wide binding patterns in HCT116 and IMR90 likely reflect the different epigenetic landscapes in these two cell lines, resulting from cancer-associated changes (accumulated in HCT116) superimposed on tissue specific differences (HCT116 has epithelial, while IMR90 has mesenchymal origin). In conclusion, our data support the model for p53 binding to the human genome in a highly selective manner, mobilizing distinct sets of genes, contributing to distinct pathways.

  2. Cell context dependent p53 genome-wide binding patterns and enrichment at repeats.

    PubMed

    Botcheva, Krassimira; McCorkle, Sean R

    2014-01-01

    The p53 ability to elicit stress specific and cell type specific responses is well recognized, but how that specificity is established remains to be defined. Whether upon activation p53 binds to its genomic targets in a cell type and stress type dependent manner is still an open question. Here we show that the p53 binding to the human genome is selective and cell context-dependent. We mapped the genomic binding sites for the endogenous wild type p53 protein in the human cancer cell line HCT116 and compared them to those we previously determined in the normal cell line IMR90. We report distinct p53 genome-wide binding landscapes in two different cell lines, analyzed under the same treatment and experimental conditions, using the same ChIP-seq approach. This is evidence for cell context dependent p53 genomic binding. The observed differences affect the p53 binding sites distribution with respect to major genomic and epigenomic elements (promoter regions, CpG islands and repeats). We correlated the high-confidence p53 ChIP-seq peaks positions with the annotated human repeats (UCSC Human Genome Browser) and observed both common and cell line specific trends. In HCT116, the p53 binding was specifically enriched at LINE repeats, compared to IMR90 cells. The p53 genome-wide binding patterns in HCT116 and IMR90 likely reflect the different epigenetic landscapes in these two cell lines, resulting from cancer-associated changes (accumulated in HCT116) superimposed on tissue specific differences (HCT116 has epithelial, while IMR90 has mesenchymal origin). Our data support the model for p53 binding to the human genome in a highly selective manner, mobilizing distinct sets of genes, contributing to distinct pathways.

  3. Cell Context Dependent p53 Genome-Wide Binding Patterns and Enrichment at Repeats

    PubMed Central

    Botcheva, Krassimira; McCorkle, Sean R.

    2014-01-01

    The p53 ability to elicit stress specific and cell type specific responses is well recognized, but how that specificity is established remains to be defined. Whether upon activation p53 binds to its genomic targets in a cell type and stress type dependent manner is still an open question. Here we show that the p53 binding to the human genome is selective and cell context-dependent. We mapped the genomic binding sites for the endogenous wild type p53 protein in the human cancer cell line HCT116 and compared them to those we previously determined in the normal cell line IMR90. We report distinct p53 genome-wide binding landscapes in two different cell lines, analyzed under the same treatment and experimental conditions, using the same ChIP-seq approach. This is evidence for cell context dependent p53 genomic binding. The observed differences affect the p53 binding sites distribution with respect to major genomic and epigenomic elements (promoter regions, CpG islands and repeats). We correlated the high-confidence p53 ChIP-seq peaks positions with the annotated human repeats (UCSC Human Genome Browser) and observed both common and cell line specific trends. In HCT116, the p53 binding was specifically enriched at LINE repeats, compared to IMR90 cells. The p53 genome-wide binding patterns in HCT116 and IMR90 likely reflect the different epigenetic landscapes in these two cell lines, resulting from cancer-associated changes (accumulated in HCT116) superimposed on tissue specific differences (HCT116 has epithelial, while IMR90 has mesenchymal origin). Our data support the model for p53 binding to the human genome in a highly selective manner, mobilizing distinct sets of genes, contributing to distinct pathways. PMID:25415302

  4. Kaempferol induces ATM/p53-mediated death receptor and mitochondrial apoptosis in human umbilical vein endothelial cells.

    PubMed

    Lee, Chiu-Fang; Yang, Jai-Sing; Tsai, Fuu-Jen; Chiang, Ni-Na; Lu, Chi-Cheng; Huang, Yu-Syuan; Chen, Chun; Chen, Fu-An

    2016-05-01

    Kaempferol is a member of the flavonoid compounds found in vegetables and fruits. It is shown to exhibit biological impact and anticancer activity, but no report exists on the angiogenic effect of kaempferol and induction of cell apoptosis in vitro. In this study, we investigated the role of kaempferol on anti-angiogenic property and the apoptotic mechanism of human umbilical vein endothelial cells (HUVECs). Our results demonstrated that kaempferol decreased HUVEC viability in a time- and concentration-dependent manner. Kaempferol also induced morphological changes and sub-G1 phase cell population (apoptotic cells). Kaempferol triggered apoptosis of HUVECs as detecting by DNA fragmentation, comet assay and immunofluorescent staining for activated caspase-3. The caspase signals, including caspase-8, -9 and -3, were time-dependently activated in HUVECs after kaempferol exposure. Furthermore, pre-treatment with a specific inhibitor of caspase-8 (Z-IETD-FMK) significantly reduced the activity of caspase-8, -9 and -3, indicating that extrinsic pathway is a major signaling pathway in kaempferol-treated HUVECs. Importantly, kaempferol promoted reactive oxygen species (ROS) evaluated using flow cytometric assay in HUVECs. We further investigated the upstream extrinsic pathway and showed that kaempferol stimulated death receptor signals [Fas/CD95, death receptor 4 (DR4) and DR5] through increasing the levels of phosphorylated p53 and phosphorylated ATM pathways in HUVECs, which can be individually confirmed by N-acetylcysteine (NAC), ATM specific inhibitor (caffeine) and p53 siRNA. Based on these results, kaempferol-induced HUVEC apoptosis was involved in an ROS-mediated p53/ATM/death receptor signaling. Kaempferol might possess therapeutic effects on cancer treatment in anti-vascular targeting.

  5. ATM/CHK/p53 Pathway Dependent Chemopreventive and Therapeutic Activity on Lung Cancer by Pterostilbene.

    PubMed

    Lee, Hani; Kim, Yonghwan; Jeong, Ji Hye; Ryu, Jae-Ha; Kim, Woo-Young

    2016-01-01

    Among the many stilbenoids found in a variety of berries, resveratrol and pterostilbene are of particular interest given their potential for use in cancer therapeutics and prevention. We purified four stilbenoids from R. undulatum and found that pterostilbene inhibits cancer cell proliferation more efficiently than rhapontigenin, piceatannol and resveratrol. To investigate the underlying mechanism of this superior action of pterostilbene on cancer cells, we utilized a reverse-phase protein array followed by bioinformatic analysis and found that the ATM/CHK pathway is modified by pterostilbene in a lung cancer cell line. Given that ATM/CHK signaling requires p53 for its biological effects, we hypothesized that p53 is required for the anticancer effect of pterostilbene. To test this hypothesis, we used two molecularly defined precancerous human bronchial epithelial cell lines, HBECR and HBECR/p53i, with normal p53 and suppressed p53 expression, respectively, to represent premalignant states of squamous lung carcinogenesis. Pterostilbene inhibited the cell cycle more efficiently in HBECR cells compared to HBECR/p53i cells, suggesting that the presence of p53 is required for the action of pterostilbene. Pterostilbene also activated ATM and CHK1/2, which are upstream of p53, in both cell lines, though pterostilbene-induced senescence was dependent on the presence of p53. Finally, pterostilbene more effectively inhibited p53-dependent cell proliferation compared to the other three stilbenoids. These results strongly support the potential chemopreventive effect of pterostilbene on p53-positive cells during early carcinogenesis.

  6. ATM/CHK/p53 Pathway Dependent Chemopreventive and Therapeutic Activity on Lung Cancer by Pterostilbene

    PubMed Central

    Lee, Hani; Kim, Yonghwan; Jeong, Ji Hye; Ryu, Jae-Ha

    2016-01-01

    Among the many stilbenoids found in a variety of berries, resveratrol and pterostilbene are of particular interest given their potential for use in cancer therapeutics and prevention. We purified four stilbenoids from R. undulatum and found that pterostilbene inhibits cancer cell proliferation more efficiently than rhapontigenin, piceatannol and resveratrol. To investigate the underlying mechanism of this superior action of pterostilbene on cancer cells, we utilized a reverse-phase protein array followed by bioinformatic analysis and found that the ATM/CHK pathway is modified by pterostilbene in a lung cancer cell line. Given that ATM/CHK signaling requires p53 for its biological effects, we hypothesized that p53 is required for the anticancer effect of pterostilbene. To test this hypothesis, we used two molecularly defined precancerous human bronchial epithelial cell lines, HBECR and HBECR/p53i, with normal p53 and suppressed p53 expression, respectively, to represent premalignant states of squamous lung carcinogenesis. Pterostilbene inhibited the cell cycle more efficiently in HBECR cells compared to HBECR/p53i cells, suggesting that the presence of p53 is required for the action of pterostilbene. Pterostilbene also activated ATM and CHK1/2, which are upstream of p53, in both cell lines, though pterostilbene-induced senescence was dependent on the presence of p53. Finally, pterostilbene more effectively inhibited p53-dependent cell proliferation compared to the other three stilbenoids. These results strongly support the potential chemopreventive effect of pterostilbene on p53-positive cells during early carcinogenesis. PMID:27612029

  7. Histone Deacetylase Inhibitor Trichostatin a Promotes the Apoptosis of Osteosarcoma Cells through p53 Signaling Pathway Activation

    PubMed Central

    Deng, Zhantao; Liu, Xiaozhou; Jin, Jiewen; Xu, Haidong; Gao, Qian; Wang, Yong; Zhao, Jianning

    2016-01-01

    Purpose: The purpose of this study was to investigate the profile of histone deacetylase (HDAC) activity and expression in osteosarcoma cells and tissues from osteosarcoma patients and to examine the mechanism by which a histone deacetylase (HDAC) inhibitor, Trichostatin A (TSA), promotes the apoptosis of osteosarcoma cells. Methods: HDAC activity and histone acetyltransferase (HAT) activity were determined in nuclear extracts of MG63 cells, hFOB 1.19 cells and tissues from 6 patients with primary osteosarcoma. The protein expression of Class I HDACs (1, 2, 3 and 8) and the activation of the p53 signaling pathway were examined by Western blot. Cell growth and apoptosis were determined by 3-(4, 5-dimethyl-2-thiazolyl)-2H-tetrazolium bromide (MTT) assay and flow cytometry, respectively. Results: Nuclear HDAC activity and class I HDAC expression were significantly higher in MG63 cells than in hFOB 1.19 cells, and a similar trend was observed in the human osteosarcoma tissues compared with the paired adjacent non-cancerous tissues. TSA significantly inhibited the growth of MG63 cells and promoted apoptosis in a dose-dependent manner through p53 signaling pathway activation. Conclusion: Class I HDACs play a central role in the pathogenesis of osteosarcoma, and HDAC inhibitors may thus have promise as new therapeutic agents against osteosarcoma. PMID:27877082

  8. Mutant p53-Notch1 Signaling Axis Is Involved in Curcumin-Induced Apoptosis of Breast Cancer Cells.

    PubMed

    Bae, Yun-Hee; Ryu, Jong Hyo; Park, Hyun-Joo; Kim, Kwang Rok; Wee, Hee-Jun; Lee, Ok-Hee; Jang, Hye-Ock; Bae, Moon-Kyoung; Kim, Kyu-Won; Bae, Soo-Kyung

    2013-08-01

    Notch1 has been reported to be highly expressed in triple-negative and other subtypes of breast cancer. Mutant p53 (R280K) is overexpressed in MDA-MB-231 triple-negative human breast cancer cells. The present study aimed to determine whether the mutant p53 can be a potent transcriptional activator of the Notch1 in MDA-MB-231 cells, and explore the role of this mutant p53-Notch1 axis in curcumin-induced apoptosis. We found that curcumin treatment resulted in an induction of apoptosis in MDA-MB-231 cells, together with downregulation of Notch1 and its downstream target, Hes1. This reduction in Notch1 expression was determined to be due to the decreased activity of endogenous mutant p53. We confirmed the suppressive effect of curcumin on Notch1 transcription by performing a Notch1 promoter-driven reporter assay and identified a putative p53-binding site in the Notch1 promoter by EMSA and chromatin immunoprecipitation analysis. Overexpression of mutant p53 increased Notch1 promoter activity, whereas knockdown of mutant p53 by small interfering RNA suppressed Notch1 expression, leading to the induction of cellular apoptosis. Moreover, curcumin-induced apoptosis was further enhanced by the knockdown of Notch1 or mutant p53, but it was decreased by the overexpression of active Notch1. Taken together, our results demonstrate, for the first time, that Notch1 is a transcriptional target of mutant p53 in breast cancer cells and suggest that the targeting of mutant p53 and/or Notch1 may be combined with a chemotherapeutic strategy to improve the response of breast cancer cells to curcumin.

  9. Structurally dependent redox property of ribonucleotide reductase subunit p53R2.

    PubMed

    Xue, Lijun; Zhou, Bingsen; Liu, Xiyong; Wang, Tieli; Shih, Jennifer; Qi, Christina; Heung, Yvonne; Yen, Yun

    2006-02-15

    p53R2 is a newly identified small subunit of ribonucleotide reductase (RR) and plays a key role in supplying precursors for DNA repair in a p53-dependent manner. Currently, we are studying the redox property, structure, and function of p53R2. In cell-free systems, p53R2 did not oxidize a reactive oxygen species (ROS) indicator carboxy-H2DCFDA, but another class I RR small subunit, hRRM2, did. Further studies showed that purified recombinant p53R2 protein has catalase activity, which breaks down H2O2. Overexpression of p53R2 reduced intracellular ROS and protected the mitochondrial membrane potential against oxidative stress, whereas overexpression of hRRM2 did not and resulted in a collapse of mitochondrial membrane potential. In a site-directed mutagenesis study, antioxidant activity was abrogated in p53R2 mutants Y331F, Y285F, Y49F, and Y241H, but not Y164F or Y164C. The fluorescence intensity in mutants oxidizing carboxy-H2DCFDA, in order from highest to lowest, was Y331F > Y285F > Y49F > Y241H > wild-type p53R2. This indicates that Y331, Y285, Y49, and Y241 in p53R2 are critical residues involved in scavenging ROS. Of interest, the ability to oxidize carboxy-H2DCFDA indicated by fluorescence intensity was negatively correlated with RR activity from wild-type p53R2, mutants Y331F, Y285F, and Y49F. Our findings suggest that p53R2 may play a key role in defending oxidative stress by scavenging ROS, and this antioxidant property is also important for its fundamental enzymatic activity.

  10. Borax-induced apoptosis in HepG2 cells involves p53, Bcl-2, and Bax.

    PubMed

    Wei, Y; Yuan, F J; Zhou, W B; Wu, L; Chen, L; Wang, J J; Zhang, Y S

    2016-06-21

    Borax, a boron compound and a salt of boric acid, is known to inhibit the growth of tumor cells. HepG2 cells have been shown to be clearly susceptible to the anti-proliferative effects of borax. However, the specific mechanisms regulating this effect are poorly understood. This study aimed to investigate the pathways underlying the growth inhibition induced by borax in HepG2 cells. The effects of borax on HepG2 cell viability were characterized using MTT. Apoptosis was also verified by annexin V/propidium iodide staining. JC-1 dye and western blotting techniques were used to measure mitochondrial membrane potential and p53, Bax, and Bcl-2 protein expression, respectively. Relevant mRNA levels were measured by qRT-PCR. Borax inhibited the proliferation of HepG2 cells in a time- and dose-dependent manner in vitro. The apoptotic process triggered by borax involved the upregulation of p53 and Bax and the downregulation of Bcl-2, which was confirmed by a change in the mitochondrial membrane potential. These results elucidate a borax-induced apoptotic pathway in HepG2 cells that involves the upregulation of p53 and Bax and the downregulation of Bcl-2.

  11. Mono(2-ethylhexyl) phthalate induces apoptosis in p53-silenced L02 cells via activation of both mitochondrial and death receptor pathways.

    PubMed

    Yang, Guangtao; Zhang, Wenjuan; Qin, Qizhi; Wang, Jing; Zheng, Hongyan; Xiong, Wei; Yuan, Jing

    2015-09-01

    Mono(2-ethylhexyl) phthalate (MEHP) is one of the main metabolites of di(2-ethylhexyl) phthalate. The evidence shows that DEHP may exert its toxic effects primarily via MEHP, which is 10-fold more potent than its parent compound in toxicity in vitro. MEHP-induced apoptosis is mediated by either p53-dependent or -independent pathway. However, the detailed mechanism of its toxicity remains unclear. In this study, immortalized normal human liver cell line L02 was chosen, as an in vitro model of nonmalignant liver, to elucidate the role of p53 in MEHP-induced apoptosis. The cells were treated with MEHP (6.25, 12.50, 25.00, 50.00, and 100.00 μM) for 24 and 36 h, then small interfering RNA (siRNA) was used to specifically silence p53 gene of L02 cells. The results indicated that MEHP caused oxidative DNA damage and apoptosis in L02 cells were associated with the p53 signaling pathway. Further study found that MEHP (50.00 and 100.00 μM) induced apoptosis in p53-silenced L02 cells, along with the up-regulations of Fas and FasL proteins as well as increased the Bax/Bcl-2 ratio and Caspase 3, 8, and 9 activities. Additionally, both FasL inhibitor (AF-016) and Caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp- fluoromethylketone (Z-VAD-FMK) could prevent the cell apoptosis induced by MEHP. The findings suggested that MEHP-induced apoptosis in L02 cells involving a Caspases-mediated mitochondrial signaling pathway and/or death receptor pathway. p53 was not absolutely necessary for MEHP-induced L02 cell apoptosis.

  12. Apoptosis in Parkinson's disease: is p53 the missing link between genetic and sporadic Parkinsonism?

    PubMed

    Alves da Costa, Cristine; Checler, Frédéric

    2011-06-01

    Parkinson's disease (PD) is a major age-related neurodegenerative disorder characterized by a massive and specific loss of dopaminergic neurons of the substantia nigra pars compacta. The cellular alterations are clinically translated into an invalidating movement disability associated to three canonical symptoms that are bradykinesia, resting tremor and rigidity. The exact causes of this neuronal loss are unknown, but a network of evidences indicates a major contribution of orchestrated cell death processes, also known as apoptosis. Apoptotic cell death is a normal process, the alteration of which triggers several pathologies including cancer and neurodegenerative disorders. Exhaustive work has been done to delineate the cellular mechanisms responsible for the exacerbated cell death of dopaminergic neurons observed in PD. Overall, the oncogene p53 has been identified as a key effector protein. This review will focus on the clues linking p53 to the etiology of PD and the evidences that this protein may be at the center of multiple signaling cascades not only altered by mutations of various proteins responsible for familial cases of PD but also on more general sporadic cases of this devastating disease. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Curcumin Significantly Enhances Dual PI3K/Akt and mTOR Inhibitor NVP-BEZ235-Induced Apoptosis in Human Renal Carcinoma Caki Cells through Down-Regulation of p53-Dependent Bcl-2 Expression and Inhibition of Mcl-1 Protein Stability

    PubMed Central

    Cho, Il Je; Kim, Sang Chan; Kwon, Taeg Kyu

    2014-01-01

    The PI3K/Akt and mTOR signaling pathways are important for cell survival and growth, and they are highly activated in cancer cells compared with normal cells. Therefore, these signaling pathways are targets for inducing cancer cell death. The dual PI3K/Akt and mTOR inhibitor NVP-BEZ235 completely inhibited both signaling pathways. However, NVP-BEZ235 had no effect on cell death in human renal carcinoma Caki cells. We tested whether combined treatment with natural compounds and NVP-BEZ235 could induce cell death. Among several chemopreventive agents, curcumin, a natural biologically active compound that is extracted from the rhizomes of Curcuma species, markedly induced apoptosis in NVP-BEZ235-treated cells. Co-treatment with curcumin and NVP-BEZ235 led to the down-regulation of Mcl-1 protein expression but not mRNA expression. Ectopic expression of Mcl-1 completely inhibited curcumin plus NVP-NEZ235-induced apoptosis. Furthermore, the down-regulation of Bcl-2 was involved in curcumin plus NVP-BEZ235-induced apoptosis. Curcumin or NVP-BEZ235 alone did not change Bcl-2 mRNA or protein expression, but co-treatment reduced Bcl-2 mRNA and protein expression. Combined treatment with NVP-BEZ235 and curcumin reduced Bcl-2 expression in wild-type p53 HCT116 human colon carcinoma cells but not p53-null HCT116 cells. Moreover, Bcl-2 expression was completely reversed by treatment with pifithrin-α, a p53-specific inhibitor. Ectopic expression of Bcl-2 also inhibited apoptosis in NVP-BE235 plus curcumin-treated cells. In contrast, NVP-BEZ235 combined with curcumin did not have a synergistic effect on normal human skin fibroblasts and normal human mesangial cells. Taken together, combined treatment with NVP-BEZ235 and curcumin induces apoptosis through p53-dependent Bcl-2 mRNA down-regulation at the transcriptional level and Mcl-1 protein down-regulation at the post-transcriptional level. PMID:24743574

  14. p16(INK4A) enhances the transcriptional and the apoptotic functions of p53 through DNA-dependent interaction.

    PubMed

    Al-Khalaf, Huda H; Nallar, Shreeram C; Kalvakolanu, Dhananjaya V; Aboussekhra, Abdelilah

    2017-02-20

    p16(INK4A) and p53 are two important tumor suppressor proteins that play essential roles during cell proliferation and aging through regulating the expression of several genes. Here, we report that p16(INK4A) and p53 co-regulate a plethora of transcripts. Furthermore, both proteins colocalize in the nucleus of human primary skin fibroblasts and breast luminal cells, and form a heteromer whose level increases in response to genotoxic stress as well as aging of human fibroblasts and various mouse organs. CDK4 is also present in this heteromeric complex, which is formed only in the presence of DNA both in vitro using pure recombinant proteins and in vivo. We have also shown that p16(INK4A) enhances the binding efficiency of p53 to its cognate sequence presents in the CDKN1A promoter in vitro, and both proteins are present at the promoters of CDKN1A and BAX in vivo. Importantly, the fourth ankyrin repeat of p16(INK4A) and the C-terminal domain of p53 were necessary for the physical association between these two proteins. The physiologic importance of this association was revealed by the inability of cancer-associated p16(INK4A) mutants to interact with p53 and to transactivate the expression of its major targets CDKN1A and BAX in the p16-defective U2OS cells expressing either wild-type or mutated p16(INK4A) . Furthermore, the association between p16(INK4A) and p53 was capital for their nuclear colocalization, the X-ray-dependent induction of p21 and Bax proteins as well as the induction of apoptosis in various types of cells. Together, these results show DNA-dependent physical interaction between p16(INK4A) and p53.

  15. Arecoline-induced growth arrest and p21WAF1 expression are dependent on p53 in rat hepatocytes.

    PubMed

    Chou, Wen-Wen; Guh, Jinn-Yuh; Tsai, Jung-Fa; Hwang, Chi-Ching; Chen, Hung-Chun; Huang, Jau-Shyang; Yang, Yu-Lin; Hung, Wen-Chun; Chuang, Lea-Yea

    2008-01-14

    Betel-quid use is associated with the risk of liver cirrhosis and hepatocellular carcinoma and arecoline, the major alkaloid of betel-quid, is hepatotoxic in mice. Therefore, we studied the cytotoxic and genotoxic effects of arecoline in normal rat hepatocytes (Clone-9 cells). Arecoline dose-dependently (0.1-1mM) decreased cell cycle-dependent proliferation while inducing DNA damage at 24h. Moreover, arecoline (1mM)-induced apoptosis and necrosis at 24h. Arecoline dose-dependently (0.1-0.5mM) increased transforming growth factor-beta (TGF-beta) mRNA, gene transcription and bioactivity and neutralizing TGF-beta antibody attenuated arecoline (0.5mM)-inhibited cell proliferation at 24h. Arecoline (0.5mM) also increased p21(WAF1) protein expression and p21(WAF1) gene transcription. Moreover, arecoline (0.5mM) time-dependently (8-24h) increased p53 serine 15 phosphorylation. Pifithrin-alpha (p53 inhibitor) and the loss of the two p53-binding elements in the p21(WAF1) gene promoter attenuated arecoline-induced p21(WAF1) gene transcription at 24h. Pifithrin-alpha also attenuated arecoline (0.5mM)-inhibited cell proliferation at 24h. We concluded that arecoline induces cytotoxicity, DNA damage, G(0)/G(1) cell cycle arrest, TGF-beta1, p21(WAF1) and activates p53 in Clone-9 cells. Moreover, arecoline-induced p21(WAF1) is dependent on p53 while arecoline-inhibited growth is dependent on both TGF-beta and p53.

  16. Phosphorylation of Tip60 by GSK-3 determines the induction of PUMA and apoptosis by p53

    PubMed Central

    Charvet, Céline; Wissler, Manuela; Brauns-Schubert, Prisca; Wang, Shang-Jui; Tang, Yi; Sigloch, Florian C.; Mellert, Hestia; Brandenburg, Martin; Lindner, Silke E.; Breit, Bernhard; Green, Douglas R.; McMahon, Steven B.; Borner, Christoph; Gu, Wei; Maurer, Ulrich

    2011-01-01

    Summary Activation of p53 by DNA damage results in either cell cycle arrest, allowing DNA repair and cell survival, or induction of apoptosis. As these opposite outcomes are both mediated by p53 stabilization, additional mechanisms to determine this decision must exist. Here we show that glycogen synthase kinase-3 (GSK-3) is required for the p53-mediated induction of the pro-apoptotic BH3 only-protein PUMA, an essential mediator of p53-induced apoptosis. Inhibition of GSK-3 protected from cell death induced by DNA damage and promoted increased long-term cell survival. We demonstrate that GSK-3 phosphorylates serine 86 of the p53-acetyltransferase Tip60. A Tip60S86A mutant was less active to induce p53 K120 acetylation, Histone 4 acetylation and expression of PUMA. Our data suggest that GSK-3 mediated Tip60S86-phosphorylation provides a link between PI3K signaling and the choice for or against apoptosis induction by p53. PMID:21658600

  17. Sirt 1 activator inhibits the AGE-induced apoptosis and p53 acetylation in human vascular endothelial cells.

    PubMed

    Li, Peng; Zhang, Lina; Zhou, Changyong; Lin, Nan; Liu, Aiguo

    2015-01-01

    Advanced glycation end products (AGEs) by nonenzymatic glycation reactions are extremely accumulated in the diabetic vascular cells, neurons, and glia, and are confirmed to play important role in the pathogenesis of diabetes mellitus -induced cardiovascular complications. Sirt 1, known as mammalian sirtuin, has been recognized to regulate insulin secretion and protect cells against oxidative stress, which is promoted by the accumulated AGEs in cardiovascular cells. In the present study, we treated human endothelial Eahy926 cells with AGEs, and determined the apoptosis induction, caspase activation, the Sirt 1 activity, the expression and acetylation of p53. Then we manipulated Sirt 1 activity with a Sirt 1 activator, Resveratrol (RSV), and a Sirt 1 inhibitor, sirtinol, in the AGE-BSA-treated Eahy926 cells, and then re-evaluated the apoptosis induction, caspase activation, the expression and acetylation of p53. Results demonstrated that AGEs induced apoptosis in the human endothelial Eahy926 cells, by promoting the cytochrome c release, activation of caspase 9/3. Also, the AGE-BSA treatment promoted the total p53 level and acetylated (Ac) p53, but reduced the Sirt 1 level and activity. On the other hand, the Sirt 1 inhibitor/activator not only deteriorated/ameliorated the promotion to p53 level and Ac p53, but also aggravated/inhibited the AGE-induced apoptosis and the promotion to apoptosis-associated signaling molecules. In conclusion, the present study confirmed the apoptosis promotion by AGEs in endothelial Eahy926 cells, by regulating the Sirt 1 activity and p53 signaling, it also implies the protective role of Sirt 1 activator against the AGE-induced apoptosis.

  18. p53 and nitric oxide are involved in cytokine-induced apoptosis in Kasumi-1 and Molt-4 Leukemics cells.

    PubMed

    Maharath, Aishath; Fucharoen, Suthat; Tanyong, Dalina I

    2014-06-01

    Immunotherapy has been developed to treat cancers. There are many signaling pathways involved in cytokine induced apoptosis of many cancers but their role remains unclear in some cancers such as leukemia. To investigate the involvement of the nitric oxide (NO) and p53 tumor suppressor gene in apoptotic pathways induced by cytokines in leukemic cell lines. Leukemic cell lines, Kasumi-1 (AML-M2) and Molt- 4 (ALL) were treated with cytokines, interleukin-1β (IL-1β), tumor necrosis factor-α (TNFα), interferon-γ (IFN-γ). The effect of cytokines on the induction cell apoptosis was analysed by flow cytometry. In addition, nitric oxide production and p53 protein levels were measured by using the Griess method and Western blot, respectively. Upon cytokine treatment, there was a significant increase in the percentage of cell apoptosis in both leukemic cell lines. The highest apoptosis was shown in 40 U/ml IFN-γ treated cells. In addition, nitric oxide and p53 protein increased in IFN-γ treated cells. There was a reduction of apoptosis and p53 level after adding the inducible nitric oxide synthase inhibitor, SMT. p53 and nitric oxide are involved in the mediation of apoptosis induced by cytokines in Kasumi-1 and Molt-4 leukemic cell lines.

  19. Mutant presenilin2 promotes apoptosis through the p53/miR-34a axis in neuronal cells.

    PubMed

    Li, Liu-Hong; Tu, Qiu-Yun; Deng, Xiao-Hua; Xia, Jian; Hou, De-Ren; Guo, Ke; Zi, Xiao-Hong

    2017-05-01

    Neurodegenerative disorders have attracted attention in last decades due to their high incidence in the world. The p53/miR-34a axis triggers apoptosis and suppresses viability in multiple types of cells, but little is known about its role in neurodegenerative diseases. In this study, we showed that presenilin (PS)-2, a major gene associated with familial Alzheimer's disease (AD) could trigger the apoptosis through the p53/miR-34a axis in PC12 cells. First we found that PC12 cell viability was downregulated by PS-2 and mutant PS-2 overexpression, especially by mutant PS-2 overexpression. Then, we established a mutant PS-2-overexpressing PC12 cell line and confirmed that mutant PS-2 induced not only p53 but also miR-34a expression. The transfection of miR-34a inhibitor reversed PS-2-induced effects on cellular viability and apoptosis. Mutant PS-2 overexpression promoted caspase-3 expression, reduced Sirt1 and Bcl-2 expression, all of which were miR-34a downstream genes related with cell apoptosis. Moreover, mutant PS-2 also activated the p53/miR-34a axis and induced apoptosis in AD transgenic mice brain. These results implied that mutant PS-2 might promote the apoptosis of neuronal cells through triggering the p53/miR-34a axis. Altogether our results provide a novel insight into neurodegenerative disease and deepen our understandings of AD pathogenic processes.

  20. WP1130 increases doxorubicin sensitivity in hepatocellular carcinoma cells through usp9x-dependent p53 degradation.

    PubMed

    Liu, Hao; Chen, Wei; Liang, Chao; Chen, Bryan Wei; Zhi, Xiao; Zhang, Shufeng; Zheng, Xiaoxiao; Bai, Xueli; Liang, Tingbo

    2015-06-01

    Resistance to chemotherapeutic drugs is a major obstacle in hepatocellular carcinoma (HCC) therapy. However, the underlying mechanisms are not well understood. Recent evidence suggests that deubiquitinases (DUB) are key regulators in the mechanisms of cell proliferation, apoptosis and chemoresistance. The present study aimed to investigate whether WP1130, which inhibits activity of deubiquitinases, exerts synergistic cytotoxicity with doxorubicin in HCC and the underlying mechanisms. In the study, we found that Huh7, HepG2, and SNU387 HCC cells with p53 expression displayed enhanced response to the combination therapy compared with p53-deficient HCC cells (Hep3B) in the manner of inhibiting cell proliferation. Downregulation of p53 abolished the synergistic cytotoxicity of doxorubicin and WP1130 on HCC cells. Mechanistically, we found that combined treatment with WP1130 suppressed doxorubicin-mediated upregulation of p53 via promoting its ubiquitin-proteasome dependent degradation, whereas knockdown of DUB usp9x abolished this effect. Taken together, these results demonstrate that combined treatment with WP1130 sensitized HCC cells to doxorubicin via usp9x-depedent p53 degradation.

  1. Apoptosis in human hepatocellular carcinoma and in liver cell dysplasia is correlated with p53 protein immunoreactivity.

    PubMed Central

    Zhao, M; Zimmermann, A

    1997-01-01

    AIMS: To investigate the prevalence of apoptosis in human hepatocellular carcinomas (HCC) of different types and grades and in liver cell dysplasia, and to test whether the apoptotic rate is correlated with the p53 protein status. METHODS: 37 HCC and 66 six liver samples with liver cell dysplasia were analysed for apoptosis using in situ DNA end labelling (ISEL), and for p53 protein expression by immunohistochemistry. In HCCs, proliferative activity was quantitatively assessed using proliferating cell nuclear antigen labelling. RESULTS: The apoptotic index in HCC as based on ISEL ranged from 0.1 to 13.5 per 1000 cells analysed and was not related to type or grade. No nuclear staining was observed in multinuclear tumour cells. There was a significant correlation between the apoptotic rate and both the proliferative activity and p53 protein reactivity. In liver samples containing p53 protein positive liver cell dysplasia cells, there was a significantly higher apoptotic rate of these cells. CONCLUSIONS: Apoptosis is detectable in HCC, and is not related to type and grade. There is a highly significant positive correlation between the apoptotic rate in HCC and both the proliferative activity and p53 protein expression. A similar phenomenon occurs for putative cancer precursors. The findings support the role of p53 in regulating apoptosis in preneoplastic and neoplastic liver lesions. Images PMID:9215122

  2. 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.

  3. MicroRNA-214 Promotes Apoptosis in Canine Hemangiosarcoma by Targeting the COP1-p53 Axis

    PubMed Central

    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. PMID:26335793

  4. Aspirin-induced nuclear translocation of NFκB and apoptosis in colorectal cancer is independent of p53 status and DNA mismatch repair proficiency

    PubMed Central

    Din, F V N; Stark, L A; Dunlop, M G

    2005-01-01

    Substantial evidence indicates nonsteroidal anti-inflammatory drugs (NSAIDs) protect against colorectal cancer (CRC). However, the molecular basis for this anti-tumour activity has not been fully elucidated. We previously reported that aspirin induces signal-specific IκBα degradation followed by NFκB nuclear translocation in CRC cells, and that this mechanism contributes substantially to aspirin-induced apoptosis. We have also reported the relative specificity of this aspirin-induced NFκB-dependent apoptotic effect for CRC cells, in comparison to other cancer cell types. It is now important to establish whether there is heterogeneity within CRC, with respect to the effects of aspirin on the NFκB pathway and apoptosis. p53 signalling and DNA mismatch repair (MMR) are known to be deranged in CRC and have been reported as potential molecular targets for the anti-tumour activity of NSAIDs. Furthermore, both p53 and MMR dysfunction have been shown to confer resistance to chemotherapeutic agents. Here, we set out to determine the p53 and hMLH1 dependency of the effects of aspirin on NFκB signalling and apoptosis in CRC. We specifically compared the effects of aspirin treatment on cell viability, apoptosis and NFκB signalling in an HCT-116 CRC cell line with the p53 gene homozygously disrupted (HCT-116p53−/−) and an HCT-116 cell line rendered MMR proficient by chromosomal transfer (HCT-116+ch3), to the parental HCT-116 CRC cell line. We found that aspirin treatment induced apoptosis following IκBα degradation, NFκB nuclear translocation and repression of NFκB-driven transcription, irrespective of p53 and DNA MMR status. These findings are relevant for design of both novel chemopreventative agents and chemoprevention trials in CRC. PMID:15770215

  5. Alkaline ceramidase 2 is a novel direct target of p53 and induces autophagy and apoptosis through ROS generation

    PubMed Central

    Wang, Yitao; Zhang, Chunxue; Jin, Yuelei; Wang; He, Qing; Liu, Zhu; Ai, Qing; Lei, Yunlong; Li, Yi; Song, Fangzhou; Bu, Youquan

    2017-01-01

    ACER2 is a critical sphingolipid metabolizing enzyme, and has been shown to be remarkably up-regulated following various stimuli such as DNA damage. However, the transcriptional regulatory mechanism of ACER2 gene and its potential role in the regulation of autophagy remain unknown. In this study, we have for the first time identified the human ACER2 gene promoter, and found that human ACER2 transcription is directly regulated by p53 and ACER2 is implicated in the induction of autophagy as well as apoptosis. A series of luciferase reporter assay demonstrated that ACER2 major promoter is located within its first intron where the consensus p53-binding sites exist. Consistently, forced expression of p53 significantly stimulated ACER2 transcription. Notably, p53-mediated autophagy and apoptosis were markedly enhanced by ACER2. Depletion of the essential autophagy gene ATG5 revealed that ACER2-induced autophagy facilitates its effect on apoptosis. Further studies clearly showed that ACER2-mediated autophagy and apoptosis are accompanied by ROS generation. In summary, our present study strongly suggests that ACER2 plays a pivotal role in p53-induced autophagy and apoptosis, and thus might serve as a novel and attractive molecular target for cancer treatment. PMID:28294157

  6. Alkaline ceramidase 2 is a novel direct target of p53 and induces autophagy and apoptosis through ROS generation.

    PubMed

    Wang, Yitao; Zhang, Chunxue; Jin, Yuelei; Wang; He, Qing; Liu, Zhu; Ai, Qing; Lei, Yunlong; Li, Yi; Song, Fangzhou; Bu, Youquan

    2017-03-15

    ACER2 is a critical sphingolipid metabolizing enzyme, and has been shown to be remarkably up-regulated following various stimuli such as DNA damage. However, the transcriptional regulatory mechanism of ACER2 gene and its potential role in the regulation of autophagy remain unknown. In this study, we have for the first time identified the human ACER2 gene promoter, and found that human ACER2 transcription is directly regulated by p53 and ACER2 is implicated in the induction of autophagy as well as apoptosis. A series of luciferase reporter assay demonstrated that ACER2 major promoter is located within its first intron where the consensus p53-binding sites exist. Consistently, forced expression of p53 significantly stimulated ACER2 transcription. Notably, p53-mediated autophagy and apoptosis were markedly enhanced by ACER2. Depletion of the essential autophagy gene ATG5 revealed that ACER2-induced autophagy facilitates its effect on apoptosis. Further studies clearly showed that ACER2-mediated autophagy and apoptosis are accompanied by ROS generation. In summary, our present study strongly suggests that ACER2 plays a pivotal role in p53-induced autophagy and apoptosis, and thus might serve as a novel and attractive molecular target for cancer treatment.

  7. Induction of apoptosis in Ehrlich ascites tumour cells via p53 activation by a novel small-molecule MDM2 inhibitor - LQFM030.

    PubMed

    da Mota, Mariana F; Cortez, Alane P; Benfica, Polyana L; Rodrigues, Bruna Dos S; Castro, Thalyta F; Macedo, Larissa M; Castro, Carlos H; Lião, Luciano M; de Carvalho, Flávio S; Romeiro, Luiz A S; Menegatti, Ricardo; Verli, Hugo; Villavicencio, Bianca; Valadares, Marize C

    2016-09-01

    The activation of the p53 pathway through the inhibition of MDM2 has been proposed as a novel therapeutic strategy against tumours. A series of cis-imidazoline analogues, termed nutlins, were reported to displace the recombinant p53 protein from its complex with MDM2 by binding to MDM2 in the p53 pocket, and exhibited an antitumour activity both in vitro and in vivo. Thus, the purpose of this study was to evaluate the antitumour properties of LQFM030 (2), a nutlin analogue created by employing the strategy of molecular simplification. LQFM030 (2) cytotoxicity was evaluated in Ehrlich ascites tumour (EAT) cells, p53 wild type, by the trypan blue exclusion test, and the mechanisms involved in EAT cell death were investigated by light and fluorescence microscopy, flow cytometry, real-time PCR and Western blotting. Our results demonstrate that LQFM030 has dose-dependent antiproliferative activity and cytotoxic activity on EAT cells, induces the accumulation of p53 protein and promotes cell cycle arrest and apoptosis. p53 gene transcription was unaffected by LQFM030 (2); however, MDM2 mRNA increased and MDM2 protein decreased. These results suggest that the small-molecule p53 activator LQFM030 (2) has the potential for further development as a novel cancer therapeutic agent. © 2016 Royal Pharmaceutical Society.

  8. Quercetin regulates the sestrin 2-AMPK-p38 MAPK signaling pathway and induces apoptosis by increasing the generation of intracellular ROS in a p53-independent manner.

    PubMed

    Kim, Guen Tae; Lee, Se Hee; Kim, Jong Il; Kim, Young Min

    2014-04-01

    The induction of apoptosis in cancer cells is a therapeutic strategy for the treatment of cancer. In the present study, we investigated the regulatory mechanisms responsible for quercetin-induced apoptosis, mamely the increased expression of sestrin 2 and the activation of the 5' AMP-activated protein kinase (AMPK)/p38 MAPK signaling pathway. Our results revealed that quercetin induced apoptosis by generating the production of intracellular reactive oxygen species (ROS) and increasing the expression of sestrin 2. The induction of apoptosis by quercetin occurred through the activation of the AMPK/p38 signaling pathway and was dependent on sestrin 2. However, the silencing of sestrin 2 using small interfering RNA (siRNA) targeting sestrin 2 revealed that quercetin did not regulate AMPK or p38 phosphorylation in the cells in which sestrin 2 was silenced. On the other hand, it has been previously reported that sestrin 2 expression is not dependent on p53 expression under hypoxic conditions, whereas DNA damage is dependent on p53. We demonstrate that the increase in the expression of sestrin 2 by quercetin-generated intracellular ROS is p53-independent. The increased expression of sestrin 2 induced apoptosis through the AMPK/p38 signaling pathway in the HT-29 colon cancer cells, which are p53 mutant, treated with quercetin. Thus, our data suggest that quercetin induces apoptosis by reducing mitochondrial membrane potential, generating intracellular ROS production and increasing sestrin 2 expression through the AMPK/p38 pathway. In addition, p53 is not a necessary element for an apoptotic event induced by sestrin 2.

  9. Quercetin regulates the sestrin 2-AMPK-p38 MAPK signaling pathway and induces apoptosis by increasing the generation of intracellular ROS in a p53-independent manner

    PubMed Central

    KIM, GUEN TAE; LEE, SE HEE; KIM, JONG IL; KIM, YOUNG MIN

    2014-01-01

    The induction of apoptosis in cancer cells is a therapeutic strategy for the treatment of cancer. In the present study, we investigated the regulatory mechanisms responsible for quercetin-induced apoptosis, mamely the increased expression of sestrin 2 and the activation of the 5′ AMP-activated protein kinase (AMPK)/p38 MAPK signaling pathway. Our results revealed that quercetin induced apoptosis by generating the production of intracellular reactive oxygen species (ROS) and increasing the expression of sestrin 2. The induction of apoptosis by quercetin occurred through the activation of the AMPK/p38 signaling pathway and was dependent on sestrin 2. However, the silencing of sestrin 2 using small interfering RNA (siRNA) targeting sestrin 2 revealed that quercetin did not regulate AMPK or p38 phosphorylation in the cells in which sestrin 2 was silenced. On the other hand, it has been previously reported that sestrin 2 expression is not dependent on p53 expression under hypoxic conditions, whereas DNA damage is dependent on p53. We demonstrate that the increase in the expression of sestrin 2 by quercetin-generated intracellular ROS is p53-independent. The increased expression of sestrin 2 induced apoptosis through the AMPK/p38 signaling pathway in the HT-29 colon cancer cells, which are p53 mutant, treated with quercetin. Thus, our data suggest that quercetin induces apoptosis by reducing mitochondrial membrane potential, generating intracellular ROS production and increasing sestrin 2 expression through the AMPK/p38 pathway. In addition, p53 is not a necessary element for an apoptotic event induced by sestrin 2. PMID:24535669

  10. Loss of p53-mediated cell-cycle arrest, senescence and apoptosis promotes genomic instability and premature aging.

    PubMed

    Li, Tongyuan; Liu, Xiangyu; Jiang, Le; Manfredi, James; Zha, Shan; Gu, Wei

    2016-03-15

    Although p53-mediated cell cycle arrest, senescence and apoptosis are well accepted as major tumor suppression mechanisms, the loss of these functions does not directly lead to tumorigenesis, suggesting that the precise roles of these canonical activities of p53 need to be redefined. Here, we report that the cells derived from the mutant mice expressing p533KR, an acetylation-defective mutant that fails to induce cell-cycle arrest, senescence and apoptosis, exhibit high levels of aneuploidy upon DNA damage. Moreover, the embryonic lethality caused by the deficiency of XRCC4, a key DNA double strand break repair factor, can be fully rescued in the p533KR/3KR background. Notably, despite high levels of genomic instability, p533KR/3KRXRCC4-/- mice, unlike p53-/- XRCC4-/- mice, are not succumbed to pro-B-cell lymphomas. Nevertheless, p533KR/3KR XRCC4-/- mice display aging-like phenotypes including testicular atrophy, kyphosis, and premature death. Further analyses demonstrate that SLC7A11 is downregulated and that p53-mediated ferroptosis is significantly induced in spleens and testis of p533KR/3KRXRCC4-/- mice. These results demonstrate that the direct role of p53-mediated cell cycle arrest, senescence and apoptosis is to control genomic stability in vivo. Our study not only validates the importance of ferroptosis in p53-mediated tumor suppression in vivo but also reveals that the combination of genomic instability and activation of ferroptosis may promote aging-associated phenotypes.

  11. Targeting GRP75 improves HSP90 inhibitor efficacy by enhancing p53-mediated apoptosis in hepatocellular carcinoma.

    PubMed

    Guo, Weiwei; Yan, Lichong; Yang, Ling; Liu, Xiaoyu; E, Qiukai; Gao, Peiye; Ye, Xiaofei; Liu, Wen; Zuo, Ji

    2014-01-01

    Heat shock protein 90 (HSP90) inhibitors are potential drugs for cancer therapy. The inhibition of HSP90 on cancer cell growth largely through degrading client proteins, like Akt and p53, therefore, triggering cancer cell apoptosis. Here, we show that the HSP90 inhibitor 17-AAG can induce the expression of GRP75, a member of heat shock protein 70 (HSP70) family, which, in turn, attenuates the anti-growth effect of HSP90 inhibition on cancer cells. Additionally, 17-AAG enhanced binding of GRP75 and p53, resulting in the retention of p53 in the cytoplasm. Blocking GRP75 with its inhibitor MKT-077 potentiated the anti-tumor effects of 17-AAG by disrupting the formation of GRP75-p53 complexes, thereby facilitating translocation of p53 into the nuclei and leading to the induction of apoptosis-related genes. Finally, dual inhibition of HSP90 and GRP75 was found to significantly inhibit tumor growth in a liver cancer xenograft model. In conclusion, the GRP75 inhibitor MKT-077 enhances 17-AAG-induced apoptosis in HCCs and increases p53-mediated inhibition of tumor growth in vivo. Dual targeting of GRP75 and HSP90 may be a useful strategy for the treatment of HCCs.

  12. Non-Thermal Atmospheric Pressure Plasma Preferentially Induces Apoptosis in p53-Mutated Cancer Cells by Activating ROS Stress-Response Pathways

    PubMed Central

    Ma, Yonghao; Ha, Chang Seung; Hwang, Seok Won; Lee, Hae June; Kim, Gyoo Cheon; Lee, Kyo-Won; Song, Kiwon

    2014-01-01

    Non-thermal atmospheric pressure plasma (NTAPP) is an ionized gas at room temperature and has potential as a new apoptosis-promoting cancer therapy that acts by generating reactive oxygen species (ROS). However, it is imperative to determine its selectivity and standardize the components and composition of NTAPP. Here, we designed an NTAPP-generating apparatus combined with a He gas feeding system and demonstrated its high selectivity toward p53-mutated cancer cells. We first determined the proper conditions for NTAPP exposure to selectively induce apoptosis in cancer cells. The apoptotic effect of NTAPP was greater for p53-mutated cancer cells; artificial p53 expression in p53-negative HT29 cells decreased the pro-apoptotic effect of NTAPP. We also examined extra- and intracellular ROS levels in NTAPP-treated cells to deduce the mechanism of NTAPP action. While NTAPP-mediated increases in extracellular nitric oxide (NO) did not affect cell viability, intracellular ROS increased under NTAPP exposure and induced apoptotic cell death. This effect was dose-dependently reduced following treatment with ROS scavengers. NTAPP induced apoptosis even in doxorubicin-resistant cancer cell lines, demonstrating the feasibility of NTAPP as a potent cancer therapy. Collectively, these results strongly support the potential of NTAPP as a selective anticancer treatment, especially for p53-mutated cancer cells. PMID:24759730

  13. Destabilization of CARP mRNAs by aloe-emodin contributes to caspase-8-mediated p53-independent apoptosis of human carcinoma cells.

    PubMed

    Lin, Meng-Liang; Lu, Yao-Cheng; Su, Hong-Lin; Lin, Hsin-Ting; Lee, Chuan-Chun; Kang, Shang-En; Lai, Tan-Chen; Chung, Jing-Gung; Chen, Shih-Shun

    2011-04-01

    Using short hairpin RNA against p53, transient ectopic expression of wild-type p53 or mutant p53 (R248W or R175H), and a p53- and p21-dependent luciferase reporter assay, we demonstrated that growth arrest and apoptosis of FaDu (human pharyngeal squamous cell carcinoma), Hep3B (hepatoma), and MG-63 (osteosarcoma) cells induced by aloe-emodin (AE) are p53-independent. Co-immunoprecipitation and small interfering RNA (siRNA) studies demonstrated that AE caused S-phase cell cycle arrest by inducing the formation of cyclin A-Cdk2-p21 complexes through extracellular signal-regulated kinase (ERK) activation. Ectopic expression of Bcl-X(L) and siRNA-mediated Bax attenuation significantly inhibited apoptosis induced by AE. Cyclosporin A or the caspase-8 inhibitor Z-IETD-FMK blocked AE-induced loss of mitochondrial membrane potential and prevented increases in reactive oxygen species and Ca(++). Z-IETD-FMK inhibited AE-induced apoptosis, Bax expression, Bid cleavage, translocation of tBid to mitochondria, ERK phosphorylation, caspase-9 activation, and the release of cytochrome c, apoptosis-inducing factor (AIF), and endonuclease G from mitochondria. The stability of the mRNAs encoding caspase-8 and -10-associated RING proteins (CARPs) 1 and 2 was affected by AE, whereas CARP1 or 2 overexpression inhibited caspase-8 activation and apoptosis induced by AE. Collectively, our data indicate AE induces caspase-8-mediated activation of mitochondrial death pathways by decreasing the stability of CARP mRNAs in a p53-independent manner.

  14. Tyrosinase overexpression promotes ATM-dependent p53 phosphorylation by quercetin and sensitizes melanoma cells to dacarbazine.

    PubMed

    Thangasamy, Thilakavathy; Sittadjody, Sivanandane; Limesand, Kirsten H; Burd, Randy

    2008-01-01

    Dacarbazine (DTIC) has been used for the treatment of melanoma for decades. However, monotherapy with this chemotherapeutic agent results only in moderate response rates. To improve tumor response to DTIC current clinical trials in melanoma focus on combining a novel targeted agent with chemotherapy. Here, we demonstrate that tyrosinase which is commonly overexpressed in melanoma activates the bioflavonoid quercetin (Qct) and promotes an ataxia telangiectasia mutated (ATM)-dependent DNA damage response. This response sensitizes melanoma cells that overexpress tyrosinase to DTIC. In DB-1 melanoma cells that overexpress tyrosinase (Tyr(+) cells), the threshold for phosphorylation of ATM and p53 at serine 15 was observed at a low dose of Qct (25 microM) when compared to the mock transfected pcDNA3 cells, which required a higher dose (75 microM). Both pcDNA3 and Tyr(+) DB-1 cells demonstrated similar increases in phosphorylation of p53 at other serine sites, but in the Tyr(+) cells, DNApk expression was found to be reduced compared to control cells, indicating a shift towards an ATM-mediated response. The DB-1 control cells were resistant to DTIC, but were sensitized to apoptosis with high dose Qct, while Tyr(+) cells were sensitized to DTIC with low or high dose Qct. Qct also sensitized SK Mel 5 (p53 wildtype) and 28 (p53 mutant) cells to DTIC. However, when SK Mel 5 cells were transiently transfected with tyrosinase and treated with Qct plus DTIC, SK Mel 5 cells demonstrated a more than additive induction of apoptosis. Therefore, this study demonstrates that tyrosinase overexpression promotes an ATM-dependent p53 phosphorylation by Qct treatment and sensitizes melanoma cells to dacarbazine. In conclusion, these results suggest that Qct or Qct analogues may significantly improve DTIC response rates in tumors that express tyrosinase.

  15. ROCK1/p53/NOXA signaling mediates cardiomyocyte apoptosis in response to high glucose in vitro and vivo.

    PubMed

    Su, Dongmei; Guan, Lina; Gao, Qianqian; Li, Qian; Shi, Cuige; Liu, Yi; Sun, Lei; Lu, Cailing; Ma, Xu; Zhao, Jing

    2017-04-01

    Gestational diabetes mellitus is a risk factor for congenital heart defects; however, the molecular basis of the congenital heart anomalies remains obscure. Previous reports showed a positive correlation between abnormal cardiomyocyte apoptosis and ventricular wall thinness, one type of congenital heart anomaly. This work explored the expression pattern and molecular mechanism of the Rho-associated coiled-coil containing protein kinase 1 (ROCK1) gene in cardiomyocyte apoptosis and genesis of ventricular wall thinness. In this report, we found a marked increase in the number of apoptotic cardiomyocytes in response to high glucose (HG) treatment. Moreover, up-regulation of ROCK1 expression observed in diabetic offspring compared with controls was potentially associated with cardiomyocyte apoptosis and the ventricular wall thinness. Further investigation showed that p53 and NOXA protein levels increased during ROCK1-meidated apoptosis in response to HG. In response to HG, whereby ROCK1 phosphorylated p53 at Ser15 to up-regulate its protein level. Furthermore, we found that p53 mediated the expression of NOXA during HG-induced apoptosis, and histone acetyltransferase p300 participated in this process. These findings reveal a novel regulatory mechanism of ROCK1/p53/NOXA signaling in modulating cardiomyocyte apoptosis in vitro and maternal diabetes-induced congenital heart defects in vivo.

  16. Novel p53-dependent anticancer strategy by targeting iron signaling and BNIP3L-induced mitophagy

    PubMed Central

    Wilfinger, Nastasia; Austin, Shane; Scheiber-Mojdehkar, Barbara; Berger, Walter; Reipert, Siegfried; Praschberger, Monika; Paur, Jakob; Trondl, Robert; Keppler, Bernhard K.; Zielinski, Christoph C.; Nowikovsky, Karin

    2016-01-01

    This study identifies BNIP3L as the key regulator of p53-dependent cell death mechanism in colon cancer cells targeted by the novel gallium based anticancer drug, KP46. KP46 specifically accumulated into mitochondria where it caused p53-dependent morphological and functional damage impairing mitochondrial dynamics and bioenergetics. Furthermore, competing with iron for cellular uptake, KP46 lowered the intracellular labile iron pools and intracellular heme. Accordingly, p53 accumulated in the nucleus where it activated its transcriptional target BNIP3L, a BH3 only domain protein with functions in apoptosis and mitophagy. Upregulated BNIP3L sensitized the mitochondrial permeability transition and strongly induced PARKIN-mediated mitochondrial clearance and cellular vacuolization. Downregulation of BNIP3L entirely rescued cell viability caused by exposure of KP46 for 24 hours, confirming that early induced cell death was regulated by BNIP3L. Altogether, targeting BNIP3L in wild-type p53 colon cancer cells is a novel anticancer strategy activating iron depletion signaling and the mitophagy-related cell death pathway. PMID:26517689

  17. Biological and molecular characterization of an ECV-304-derived cell line resistant to p53-mediated apoptosis.

    PubMed

    Maxwell, S A; Davis, G E

    2000-06-01

    Upregulation of the p53 tumor suppressor protein by infection with a recombinant p53 adenovirus resulted in extensive apoptosis in ECV-304 cells and the eventual death of almost all the cells. To establish a system to elucidate the molecular mechanisms involved in p53-mediated apoptosis of these cells, we established a variant of ECV-304 that is resistant to p53-induced apoptosis by repeated infections with a recombinant p53 adenovirus. We have designated this variant as the DECV cell line (Differentiated ECV-304). DECV cells expressed similar amounts of nuclear-localized p53 as ECV-304 cells when infected with recombinant p53 adenovirus, but in contrast to ECV-304 cells, greater than 95% of DECV cells survived and remained viable after 24 hours of infection. In further contrast to ECV-304 cells, DECV cells grew less efficiently in soft agar and exhibited contact inhibition in growth assays. Moreover, DECV cells formed unusual lattice or cyst-like structures in culture and formed lumenal structures indicative of epithelial differentiation in three-dimensional collagen matrices, while parental ECV-304 cells showed minimal evidence of these cellular behaviors. A comparative molecular analysis of gene expression in DECV and ECV-304 cells was conducted by cDNA microarray technology. Protocadherin-1 was found to be expressed in DECV cells but not in ECV-304 cells, while the Id-3 gene was observed expressed in ECV-304 cells but not in DECV cells. Moreover, upregulated expression of p53 in ECV-304 cells induced the EPHB2 (Ephrin) receptor tyrosine kinase and the ephrin-B1 ligand mRNAs compared to DECV cells treated in the same manner. These data demonstrate that a new variant of the ECV-304 cell line, which is resistant to p53-mediated apoptosis, exhibits differential gene expression as well as distinct cell behaviors as compared to the parental ECV-304 cell line. DECV cells should prove to be a useful tool in future studies to elucidate mechanisms of p53-mediated

  18. p53-dependent expression of CXCR5 chemokine receptor in MCF-7 breast cancer cells.

    PubMed

    Mitkin, Nikita A; Hook, Christina D; Schwartz, Anton M; Biswas, Subir; Kochetkov, Dmitry V; Muratova, Alisa M; Afanasyeva, Marina A; Kravchenko, Julia E; Bhattacharyya, Arindam; Kuprash, Dmitry V

    2015-03-19

    Elevated expression of chemokine receptors in tumors has been reported in many instances and is related to a number of survival advantages for tumor cells including abnormal activation of prosurvival intracellular pathways. In this work we demonstrated an inverse correlation between expression levels of p53 tumor suppressor and CXCR5 chemokine receptor in MCF-7 human breast cancer cell line. Lentiviral transduction of MCF-7 cells with p53 shRNA led to elevated CXCR5 at both mRNA and protein levels. Functional activity of CXCR5 in p53-knockdown MCF-7 cells was also increased as shown by activation of target gene expression and chemotaxis in response to B-lymphocyte chemoattractant CXCL13. Using deletion analysis and site-directed mutagenesis of the cxcr5 gene promoter and enhancer elements, we demonstrated that p53 appears to act upon cxcr5 promoter indirectly, by repressing the activity of NFκB transcription factors. Using chromatin immunoprecipitation and reporter gene analysis, we further demonstrated that p65/RelA was able to bind the cxcr5 promoter in p53-dependent manner and to directly transactivate it when overexpressed. Through the described mechanism, elevated CXCR5 expression may contribute to abnormal cell survival and migration in breast tumors that lack functional p53.

  19. Inhibition of Cathepsin S Induces Mitochondrial ROS That Sensitizes TRAIL-Mediated Apoptosis Through p53-Mediated Downregulation of Bcl-2 and c-FLIP.

    PubMed

    Seo, Bo Ram; Min, Kyoung-Jin; Woo, Seon Min; Choe, Misun; Choi, Kyeong Sook; Lee, Young-Kyung; Yoon, Gyesoon; Kwon, Taeg Kyu

    2017-08-01

    Cathepsin S is highly expressed in various cancer cells, and it has protumoral effects, including promotion of migration, invasion, and neovascularization. In this study, we show that inhibition of cathepsin S could sensitize cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. An inhibitor of cathepsin S (Z-FL-COCHO; ZFL) markedly induced apoptosis in human renal cancer cells treated with TRAIL. In contrast, combined treatment with ZFL and TRAIL had no effect on normal cells. ZFL downregulated Bcl-2 expression at the transcriptional level in a p53-dependent manner, and overexpression of Bcl-2 also markedly blocked apoptosis induced by combined treatment with ZFL and TRAIL. In addition, ZFL induced downregulation of c-FLIP, and overexpression of c-FLIP blocked the apoptosis induced by ZFL plus TRAIL. Moreover, ZFL increased the expression of Cbl, an E3 ligase of c-FLIP, in a p53-dependent manner, and knockdown of Cbl markedly prevented c-FLIP downregulation and the apoptosis induced by ZFL plus TRAIL. Interestingly, ZFL induced p53 expression via production of mitochondrial reactive oxygen species (ROS). We also demonstrated that downregulation of cathepsin S by small interfering RNA sensitized TRAIL-mediated apoptosis in Caki cells. These results reveal the importance of cathepsin S on resistance against TRAIL, and inhibition of cathepsin S activity plays a crucial role in TRAIL-mediated cell death of cancer cells. Our results indicated that inhibition of cathepsin S stimulates TRAIL-induced apoptosis through downregulation of Bcl-2 and Cbl-mediated c-FLIP by ROS-mediated p53 expression. Antioxid. Redox Signal. 27, 215-233.

  20. Structural Basis for p53 Lys120-Acetylation-Dependent DNA-Binding Mode.

    PubMed

    Vainer, Radion; Cohen, Sarit; Shahar, Anat; Zarivach, Raz; Arbely, Eyal

    2016-07-31

    Normal cellular homeostasis depends on tight regulation of gene expression, which requires the modulation of transcription factors' DNA-binding specificity. That said, the mechanisms that allow transcription factors to distinguish between closely related response elements following different cellular signals are not fully understood. In the tumor suppressor protein p53, acetylation of loop L1 residue Lys120 within the DNA-binding domain has been shown to promote the transcription of proapoptotic genes such as bax. Here, we report the crystal structures of Lys120-acetylated p53 DNA-binding domain in complex with a consensus response element and with the natural BAX response element. Our structural analyses reveal that Lys120 acetylation expands the conformational space of loop L1 in the DNA-bound state. Loop L1 flexibility is known to increase p53's DNA-binding specificity, and Lys120-acetylation-dependent conformational changes in loop L1 enable the formation of sequence-dependent DNA-binding modes for p53. Furthermore, binding to the natural BAX response element is accompanied by global conformational changes, deformation of the DNA helical structure, and formation of an asymmetric tetrameric complex. Based on these findings, we suggest a model for p53's Lys120 acetylation-dependent DNA-binding mode. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. p53 promotes cellular survival in a context-dependent manner by directly inducing the expression of haeme-oxygenase-1.

    PubMed

    Nam, S Y; Sabapathy, K

    2011-11-03

    A variety of cellular insults activate the tumour suppressor p53, leading generally to cell-cycle arrest or apoptosis. However, it is not inconceivable that cellular protective mechanisms may be required to keep cells alive while cell-fate decisions are made. In this respect, p53 has been suggested to perform functions that allow cells to survive, by halting of the cell-cycle, and thus preventing immediate cell death. Nonetheless, the existence of direct pro-survival p53 target genes regulating cellular survival is lacking. We show here evidence for p53-dependent cellular survival in a context-dependent manner. Both mouse and human cells lacking p53 are hypersensitive to hydrogen peroxide (H(2)O(2))-induced cell death compared with their isogenic wild-type counterparts. By contrast, p53(-/-) cells are expectedly resistant to cell death upon exposure to DNA-damaging agents such as cisplatin (CDDP) and etoposide. Although p53 and its classical targets such as p21 and Mdm2 are activated by both H(2)O(2) and CDDP, we found that the expression of haeme-oxygenase-1 (HO-1)-an antioxidant and antiapoptotic protein-was directly induced only upon H(2)O(2) treatment in a p53-dependent manner. Consistently, p53, but not its homologue p73, activated HO-1 expression and was bound to the HO-1 promoter specifically only upon H(2)O(2) treatment. Moreover, silencing HO-1 expression enhanced cell death upon H(2)O(2) treatment only in p53-proficient cells. Finally, H(2)O(2)-mediated cell death was rescued significantly in p53-deficient cells by antioxidant treatment, as well as by bilirubin, a by-product of HO-1 metabolism. Taken together, these data demonstrate a direct role for p53 in promoting cellular survival in a context-specific manner through the activation of a direct transcriptional target, HO-1.

  2. Peroxiredoxin 2 battles PARP1- and p53-dependent pro-death pathways following ischemic injury

    PubMed Central

    Leak, Rehana K.; Zhang, Lili; Luo, Yumin; Li, Peiying; Zhao, Haiping; Liu, Xiangrong; Ling, Feng; Jia, Jianping; Chen, Jun; Ji, Xunming

    2013-01-01

    Background and Purpose Ischemic/reperfusion neuronal injury is characterized by accumulation of reactive oxygen species (ROS) and oxidative DNA damage, which can trigger cell death by various signaling pathways. Two of these modes of death include poly(ADP-ribose) polymerase 1 (PARP1)-mediated death or p53- and Bax-mediated apoptosis. The present study tested the hypothesis that peroxiredoxin2 (PRX2) attenuates DNA damage-mediated pro-death signaling using in vitro and in vivo models of ischemic injury. The impact of this peroxide scavenger on p53- and PARP1-mediated ischemic death is unknown. Methods Neuronal PRX2 overexpression in primary cortical cultures and transgenic mice was combined with the PARP1 inhibitor AG14361. AG14361 was also applied to p53 and Bax knockout cultures and mice and combined with the JNK inhibitor SP600125. DCF fluorescence, AP sites, single-strand breaks, Comet tail-length, NAD+ depletion, and viability were assessed in response to oxygen-glucose deprivation in cultures or transient focal cerebral ischemia in mice. Results PRX2 attenuated ROS, DNA damage, NAD+ depletion, and cell death. PRX2 knockdown exacerbated neuronal death following OGD. PRX2 ameliorated PARP1, p53, Bax, and caspase activation following ischemia. AG14361 reduced ischemic cell death in wild-type and p53 or Bax knockout cultures and animals but had no additional effect in PRX2-overexpressing mice. AG14361 and p53 knockout elicited additive effects with SP600125 on viability in vitro. Our findings support the existence of multiple parallel pro-death pathways with some crosstalk. Conclusions The promising therapeutic candidate PRX2 can clamp upstream DNA damage and efficiently inhibit multiple pro-death cascades operating in both parallel and interactive fashions. PMID:23429506

  3. Potential therapeutic role of Tridham in human hepatocellular carcinoma cell line through induction of p53 independent apoptosis

    PubMed Central

    2013-01-01

    Background Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths reported worldwide. The incidence is higher in Asia and Africa, where there is greater endemic prevalence of hepatitis B and C. The devastating outcome of cancer can be minimized only by the use of potent therapeutic agents. Tridham (TD) has been acknowledged since olden days for its wide spectrum of biological properties and was used by traditional practitioners of Siddha and other indigenous systems of medicine. The present study aims at investigating the mechanistic action of TD by assessing the antiproliferative and pro-apoptotic effects on human hepatocellular carcinoma cell line (Huh7). Methods Cell viability and apoptosis assay using MTT analysis and trypan blue staining, DAPI staining, DNA fragmentation, cell cycle analysis, mitochondrial membrane potential, real-time reverse transcription-polymerase chain reaction, western blotting and immunofluorescence staining were determined in Huh7 cells. Results Viability studies of TD treated Huh7 cells showed an inhibition in cell growth in time and dose dependent manner. Chromatin condensation, DNA fragmentation and apoptotic bodies, which are structural changes characteristic of apoptosis, were found following TD treatment of Huh7 cells. DAPI staining and agarose gel electrophoresis confirmed the induction of apoptosis by TD. Cell cycle analysis of Huh7 cells treated with TD exhibited a marked accumulation of cells in the sub-G1 phase of the cell cycle in a dose dependent manner. Immunofluorescent staining for Ki-67 showed a higher level of expression in untreated cells as compared to TD treated cells. We observed a significant loss in the mitochondrial membrane potential and the release of cytochrome c into the cytosol in TD treated cells. Down regulation of Bcl-2, up regulation of Bax and Bad as well as activation of caspases-3 and 9 were also observed. The p53 gene expression was found to be unaltered in TD treated cells

  4. Increased p53 and decreased p21 accompany apoptosis induced by ultraviolet radiation in the nervous system of a crustacean.

    PubMed

    Hollmann, Gabriela; Linden, Rafael; Giangrande, Angela; Allodi, Silvana

    2016-04-01

    Ultraviolet (UV) radiation can produce biological damage, leading the cell to apoptosis by the p53 pathway. This study evaluated some molecular markers of the apoptosis pathway induced by UVA, UVB and UVA+ UVB (Solar Simulator, SIM) in environmental doses, during five consecutive days of exposure, in the brain of the crab Ucides cordatus. We evaluated the central nervous system (CNS) by immunoblotting the content of proteins p53, p21, phosphorylated AKT, BDNF, GDNF, activated caspase-3 (C3) and phosphohistone H3 (PH3); and by immunohistochemical tests of the cells labeled for PH3 and C3. After the fifth day of exposure, UVB radiation and SIM increased the protein content of p53, increasing the content of AKT and, somehow, blocking p21, increasing the content of activated caspase-3, which led the cells to apoptosis. The signs of death affected the increase in neurotrophins, such as BDNF and GDNF, stimulating the apoptotic cascade of events. Immunohistochemical assays and immunoblotting showed that apoptosis was present in the brains of all UV groups, while the number of mitotic cells in the same groups decreased. In conclusion, environmental doses of UV can cause apoptosis by increasing p53 and decreasing p21, revealing an UV-damage pathway for U. cordatus. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Depletion of hepatoma-derived growth factor-related protein-3 induces apoptotic sensitization of radioresistant A549 cells via reactive oxygen species-dependent p53 activation

    SciTech Connect

    Yun, Hong Shik; Hong, Eun-Hee; Lee, Su-Jae; Baek, Jeong-Hwa; Lee, Chang-Woo; Yim, Ji-Hye; Um, Hong-Duck; Hwang, Sang-Gu

    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 phenotype 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.

  6. Combining p53 stabilizers with metformin induces synergistic apoptosis through regulation of energy metabolism in castration-resistant prostate cancer

    PubMed Central

    Chen, Long; Ahmad, Nihal; Liu, Xiaoqi

    2016-01-01

    ABSTRACT Since altered energy metabolism is a hallmark of cancer, many drugs targeting metabolic pathways are in active clinical trials. The tumor suppressor p53 is often inactivated in cancer, either through downregulation of protein or loss-of-function mutations. As such, stabilization of p53 is considered as one promising approach to treat those cancers carrying wild type (WT) p53. Herein, SIRT1 inhibitor Tenovin-1 and polo-like kinase 1 (Plk1) inhibitor BI2536 were used to stabilize p53. We found that both Tennovin-1 and BI2536 increased the anti-neoplastic activity of metformin, an inhibitor of oxidative phosphorylation, in a p53 dependent manner. Since p53 has also been shown to regulate metabolic pathways, we further analyzed glycolysis and oxidative phosphorylation upon drug treatments. We showed that both Tennovin-1 and BI2536 rescued metformin-induced glycolysis and that both Tennovin-1 and BI2536 potentiated metformin-associated inhibition of oxidative phosphorylation. Of significance, castration-resistant prostate cancer (CRPC) C4-2 cells show a much more robust response to the combination treatment than the parental androgen-dependent prostate cancer LNCaP cells, indicating that targeting energy metabolism with metformin plus p53 stabilizers might be a valid approach to treat CRPC carrying WT p53. PMID:26900800

  7. Abnormal mitosis triggers p53-dependent cell cycle arrest in human tetraploid cells.

    PubMed

    Kuffer, Christian; Kuznetsova, Anastasia Yurievna; Storchová, Zuzana

    2013-08-01

    Erroneously arising tetraploid mammalian cells are chromosomally instable and may facilitate cell transformation. An increasing body of evidence shows that the propagation of mammalian tetraploid cells is limited by a p53-dependent arrest. The trigger of this arrest has not been identified so far. Here we show by live cell imaging of tetraploid cells generated by an induced cytokinesis failure that most tetraploids arrest and die in a p53-dependent manner after the first tetraploid mitosis. Furthermore, we found that the main trigger is a mitotic defect, in particular, chromosome missegregation during bipolar mitosis or spindle multipolarity. Both a transient multipolar spindle followed by efficient clustering in anaphase as well as a multipolar spindle followed by multipolar mitosis inhibited subsequent proliferation to a similar degree. We found that the tetraploid cells did not accumulate double-strand breaks that could cause the cell cycle arrest after tetraploid mitosis. In contrast, tetraploid cells showed increased levels of oxidative DNA damage coinciding with the p53 activation. To further elucidate the pathways involved in the proliferation control of tetraploid cells, we knocked down specific kinases that had been previously linked to the cell cycle arrest and p53 phosphorylation. Our results suggest that the checkpoint kinase ATM phosphorylates p53 in tetraploid cells after abnormal mitosis and thus contributes to proliferation control of human aberrantly arising tetraploids.

  8. MDM2 Inhibition Sensitizes Prostate Cancer Cells to Androgen Ablation and Radiotherapy in a p53-Dependent Manner12

    PubMed Central

    Feng, Felix Y.; Zhang, Yu; Kothari, Vishal; Evans, Joseph R.; Jackson, William C.; Chen, Wei; Johnson, Skyler B.; Luczak, Connor; Wang, Shaomeng; Hamstra, Daniel A.

    2016-01-01

    PURPOSE: Increased murine double minute 2 (MDM2) expression, independent of p53 status, is associated with increased cancer-specific mortality for men with prostate cancer treated with radiotherapy. We assessed MI-219, a small molecule inhibitor of MDM2 with improved pharmacokinetics over nutlin-3, for sensitization of prostate cancer cells to radiotherapy and androgen deprivation therapy, a standard treatment option for men with high-risk prostate cancer. EXPERIMENTAL DESIGN: The effect of MDM2 inhibition by MI-219 was assessed in vitro and in vivo with mouse xenograft models across multiple prostate cancer cell lines containing varying p53 functional status. RESULTS: MDM2 inhibition by MI-219 resulted in dose- and time-dependent p53 activation and decreased clonogenic cell survival after radiation in a p53-dependent manner. Mechanistically, radiosensitization following inhibition of MDM2 was largely the result of p53-dependent increases in apoptosis and DNA damage as evidenced by Annexin V flow cytometry and γ-H2AX foci immunofluorescence. Similarly, treatment with MI-219 enhanced response to antiandrogen therapy via a p53-dependent increase in apoptotic cell death. Lastly, triple therapy with radiation, androgen deprivation therapy, and MI-219 decreased xenograft tumor growth compared with any single- or double-agent treatment. CONCLUSION: MDM2 inhibition with MI-219 results in p53-dependent sensitization of prostate cancer cells to radiation, antiandrogen therapy, and the combination. These findings support MDM2 small molecule inhibitor therapy as a therapy intensification strategy to improve clinical outcomes in high-risk localized prostate cancer. TRANSLATIONAL RELEVANCE: The combination of radiotherapy and androgen deprivation therapy is a standard treatment option for men with high-risk prostate cancer. Despite improvements in outcomes when androgen deprivation therapy is added to radiation, men with high-risk prostate cancer have significant risk for

  9. Roles of p53 and caspases in the induction of cell cycle arrest and apoptosis by HIV-1 vpr.

    PubMed

    Shostak, L D; Ludlow, J; Fisk, J; Pursell, S; Rimel, B J; Nguyen, D; Rosenblatt, J D; Planelles, V

    1999-08-25

    The vpr gene from the human immunodeficiency virus type-1 (HIV-1) encodes a 14-kDa protein that prevents cell proliferation by causing a block in the G(2) phase of the cell cycle. This cellular function of vpr is conserved in evolution because other primate lentiviruses, including HIV-2, SIV(mac), and SIV(agm) encode related genes that also induce G(2) arrest. After G(2) arrest, cells expressing vpr undergo apoptosis. The signaling pathways that result in vpr-induced cell cycle arrest and apoptosis have yet to be determined. The p53 tumor suppressor protein is involved in signaling pathways leading to cell cycle arrest and apoptosis in a variety of cell types. In this work, we examine the potential role of p53 in mediating cell cycle block and/or apoptosis by HIV-1 vpr and demonstrate that both phenomena occur independently of the presence and function of p53. Caspases are common mediators of apoptosis. We examined the potential role of caspases in mediating vpr-induced apoptosis by treating vpr-expressing cells with Boc-D-FMK, a broad spectrum, irreversible inhibitor of the caspase family. Boc-D-FMK significantly reduced the numbers of apoptotic cells induced by vpr. Therefore, we conclude that vpr-induced apoptosis is effected via the activation of caspases. Copyright 1999 Academic Press.

  10. p53-Dependent PUMA to DRAM antagonistic interplay as a key molecular switch in cell-fate decision in normal/high glucose conditions.

    PubMed

    Garufi, Alessia; Pistritto, Giuseppa; Baldari, Silvia; Toietta, Gabriele; Cirone, Mara; D'Orazi, Gabriella

    2017-09-11

    As an important cellular stress sensor phosphoprotein p53 can trigger cell cycle arrest and apoptosis and regulate autophagy. The p53 activity mainly depends on its transactivating function, however, how p53 can select one or another biological outcome is still a matter of profound studies. Our previous findings indicate that switching cancer cells in high glucose (HG) impairs p53 apoptotic function and the transcription of target gene PUMA. Here we report that, in response to drug adriamycin (ADR) in HG, p53 efficiently induced the expression of DRAM (damage-regulated autophagy modulator), a p53 target gene and a stress-induced regulator of autophagy. We found that ADR treatment of cancer cells in HG increased autophagy, as displayed by greater LC3II accumulation and p62 degradation compared to ADR-treated cells in low glucose. The increased autophagy in HG was in part dependent on p53-induced DRAM; indeed DRAM knockdown with specific siRNA reversed the expression of the autophagic markers in HG. A similar outcome was achieved by inhibiting p53 transcriptional activity with pifithrin-α. DRAM knockdown restored the ADR-induced cell death in HG to the levels obtained in low glucose. A similar outcome was achieved by inhibition of autophagy with cloroquine (CQ) or with silencing of autophagy gene ATG5. DRAM knockdown or inhibition of autophagy were both able to re-induce PUMA transcription in response to ADR, underlining a reciprocal interplay between PUMA to DRAM to unbalance p53 apoptotic activity in HG. Xenograft tumors transplanted in normoglycemic mice displayed growth delay after ADR treatment compared to those transplanted in diabetics mice and such different in vivo response correlated with PUMA to DRAM gene expression. Altogether, these findings suggest that in normal/high glucose condition a mutual unbalance between p53-dependent apoptosis (PUMA) and autophagy (DRAM) gene occurred, modifying the ADR-induced cancer cell death in HG both in vitro and in vivo.

  11. 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.

  12. Involvement of tumor suppressor protein p53 and p38 MAPK in caffeic acid phenethyl ester-induced apoptosis of C6 glioma cells.

    PubMed

    Lee, Yean-Jang; Kuo, Hsing-Chun; Chu, Chia-Yih; Wang, Chau-Jong; Lin, Wan-Chyi; Tseng, Tsui-Hwa

    2003-12-15

    Caffeic acid phenethyl ester (CAPE), an active component of propolis, has many biological and pharmacological activities including antioxidant, anti-inflammation, antiviral action, and anticancer effect. Our previous studies showed that CAPE exhibited significant cytotoxicity in oral cancer cells. Herein we further investigated the cytotoxicity potential of CAPE and the mechanism of its action in C6 glioma cells. The data exhibited that C6 glioma cells underwent internucleosomal DNA fragmentation 24 hr after the treatment of CAPE (50 microM). The proportion of C6 glioma cells with hypodiploid nuclei was increased to 24% at 36 hr after the exposure. Further results showed that CAPE induced the release of cytochrome c from mitochondria into cytosol, and the activation of CPP32. CAPE application also enhanced the expression of p53, Bax, and Bak. Finally, the potential signaling components underlying CAPE induction of apoptosis were elucidated. We found that CAPE activated extracellular signal-regulated kinase (ERKs) and p38 mitogen-activated protein kinase (p38 MAPK) in C6 glioma cells. More importantly, p38 kinase formed a complex with p53 after the treatment of CAPE for 0.5 hr. The expression of p53, phospho-serine 15 of p53, and Bax, and inactivate form of CPP32 was suppressed by a pretreatment of a specific p38 MAPK inhibitor, SB203580. The resultant data suggest that p38 MAPK mediated the CAPE-induced p53-dependent apoptosis in C6 glioma cells.

  13. The APC/C cofactor Cdh1 prevents replicative stress and p53-dependent cell death in neural progenitors.

    PubMed

    Eguren, Manuel; Porlan, Eva; Manchado, Eusebio; García-Higuera, Irene; Cañamero, Marta; Fariñas, Isabel; Malumbres, Marcos

    2013-01-01

    The E3-ubiquitin ligase APC/C-Cdh1 is essential for endoreduplication but its relevance in the mammalian mitotic cell cycle is still unclear. Here we show that genetic ablation of Cdh1 in the developing nervous system results in hypoplastic brain and hydrocephalus. These defects correlate with enhanced levels of Cdh1 substrates and increased entry into the S phase in neural progenitors. However, cell division is prevented in the absence of Cdh1 due to hyperactivation of cyclin-dependent kinases, replicative stress, induction of p53, G2 arrest and apoptotic death of these progenitor cells. Concomitant ablation of p53 rescues apoptosis but not replicative stress, resulting in the presence of damaged neurons throughout the adult brain. These data indicate that the inactivation of Cdh1 in vivo results in replicative stress, cell cycle arrest and cell death, supporting recent therapeutic proposals aimed to inhibit the APC/C in tumours.

  14. Resveratrol attenuates doxorubicin-induced cardiomyocyte apoptosis in mice through SIRT1-mediated deacetylation of p53.

    PubMed

    Zhang, Chi; Feng, Yansheng; Qu, Shunlin; Wei, Xing; Zhu, Honglin; Luo, Qi; Liu, Meidong; Chen, Guangwen; Xiao, Xianzhong

    2011-06-01

    Doxorubicin (DOX) is an anthracycline drug with a wide spectrum of clinical antineoplastic activity, but increased apoptosis has been implicated in its cardiotoxicity. Resveratrol (RES) was shown to harbour major health benefits in diseases associated with oxidative stress. In this study, we aimed to determine the effect of RES on DOX-induced myocardial apoptosis in mice. Male Balb/c mice were randomized to one of the following four treatments: saline, RES, DOX, or RES plus DOX (10 mice in each group). DOX treatment markedly depressed cardiac function, decreased the heart weight, the body weight, and the ratio of heart weight to body weight, but inversely increased the level of protein carbonyl, malondialdehyde, and serum lactate dehydrogenase, and induced mitochondrial cytochrome c release and cardiomyocyte apoptosis. However, these effects of DOX were ameliorated by its combination with RES. Further studies with a co-immunoprecipitation assay revealed an interaction between p53 and Sirtuin 1 (SIRT1). It was found by western blot and electrophoretic mobility shift assay that DOX treatment increased p53 protein acetylation and cytochrome c release from mitochondria, activated p53 binding at the Bax promoter, and up-regulated Bax expression, but supplementation with RES could weaken all these effects. The protective effect of RES against DOX-induced cardiomyocyte apoptosis is associated with the up-regulation of SIRT1-mediated p53 deacetylation.

  15. Chlamydia infection depends on a functional MDM2-p53 axis.

    PubMed

    González, Erik; Rother, Marion; Kerr, Markus C; Al-Zeer, Munir A; Abu-Lubad, Mohammad; Kessler, Mirjana; Brinkmann, Volker; Loewer, Alexander; Meyer, Thomas F

    2014-11-13

    Chlamydia, a major human bacterial pathogen, assumes effective strategies to protect infected cells against death-inducing stimuli, thereby ensuring completion of its developmental cycle. Paired with its capacity to cause extensive host DNA damage, this poses a potential risk of malignant transformation, consistent with circumstantial epidemiological evidence. Here we reveal a dramatic depletion of p53, a tumor suppressor deregulated in many cancers, during Chlamydia infection. Using biochemical approaches and live imaging of individual cells, we demonstrate that p53 diminution requires phosphorylation of Murine Double Minute 2 (MDM2; a ubiquitin ligase) and subsequent interaction of phospho-MDM2 with p53 before induced proteasomal degradation. Strikingly, inhibition of the p53-MDM2 interaction is sufficient to disrupt intracellular development of Chlamydia and interferes with the pathogen's anti-apoptotic effect on host cells. This highlights the dependency of the pathogen on a functional MDM2-p53 axis and lends support to a potentially pro-carcinogenic effect of chlamydial infection.

  16. Drosophila p53 controls Notch expression and balances apoptosis and proliferation.

    PubMed

    Simón, Rocío; Aparicio, Ricardo; Housden, Ben E; Bray, Sarah; Busturia, Ana

    2014-10-01

    A balance between cell proliferation and apoptosis is important for normal development and tissue homeostasis. Under stress conditions, the conserved tumor suppressor and transcription factor Dp53 induces apoptosis to contribute to the maintenance of homeostasis. However, in some cases Dp53-induced apoptosis results in the proliferation of surrounding non-apoptotic cells. To gain insight into the Dp53 function in the control of apoptosis and proliferation, we studied the interaction between the Drosophila Dp53 and Notch genes. We present evidence that simultaneous reduction of Dp53 and Notch function synergistically increases the wing phenotype of Notch heterozygous mutant flies. Further, we found that a Notch cis-regulatory element is responsive to loss and gain of Dp53 function and that over-expression of Dp53 up-regulates Notch mRNA and protein expression. These findings suggest not only that Dp53 and Notch act together to control wing development but also indicate that Dp53 transcriptionally regulates Notch expression. Moreover, using Notch  gain and loss of function mutations we examined the relevance of Dp53 and Notch interactions in the process of Dp53-apoptosis induced proliferation. Results show that proliferation induced by Dp53 over-expression is dependent on Notch, thus identifying Notch as a new player in Dp53-induced proliferation. Interestingly, we found that Dp53-induced Notch activation and proliferation occurs even under conditions where apoptosis was inhibited. Our findings highlight the conservation between flies and vertebrates of the Dp53 and Notch cross-talk and suggest that Dp53 has a dual role regulating cell death and proliferation gene networks to control the homeostatic balance between apoptosis and proliferation.

  17. Fisetin Induces Apoptosis Through p53-Mediated Up-Regulation of DR5 Expression in Human Renal Carcinoma Caki Cells.

    PubMed

    Min, Kyoung-Jin; Nam, Ju-Ock; Kwon, Taeg Kyu

    2017-08-02

    Fisetin is a natural compound found in fruits and vegetables such as strawberries, apples, cucumbers, and onions. Since fisetin can elicit anti-cancer effects, including anti-proliferation and anti-migration, we investigated whether fisetin induced apoptosis in human renal carcinoma (Caki) cells. Fisetin markedly induced sub-G1 population and cleavage of poly (ADP-ribose) polymerase (PARP), which is a marker of apoptosis, and increased caspase activation. We found that pan-caspase inhibitor (z-VAD-fmk) inhibited fisetin-induced apoptosis. In addition, fisetin induced death receptor 5 (DR5) expression at the transcriptional level, and down-regulation of DR5 by siRNA blocked fisetin-induced apoptosis. Furthermore, fisetin induced p53 protein expression through up-regulation of protein stability, whereas down-regulation of p53 by siRNA markedly inhibited fisetin-induced DR5 expression. In contrast, fisetin induced up-regulation of CHOP expression and reactive oxygen species production, which had no effect on fisetin-induced apoptosis. Taken together, our study demonstrates that fisetin induced apoptosis through p53 mediated up-regulation of DR5 expression at the transcriptional level.

  18. The p53 co-activator Zac1 neither induces cell cycle arrest nor apoptosis in chicken Lim1 horizontal progenitor cells.

    PubMed

    Fard, S Shirazi; Blixt, Mke; Hallböök, F

    2015-01-01

    Chicken horizontal progenitor cells are able to enter their final mitosis even in the presence of DNA damage despite having a functional p53-p21 system. This suggests that they are resistant to DNA damage and that the regulation of the final cell cycle of horizontal progenitor cells is independent of the p53-p21 system. The activity of p53 is regulated by positive and negative modulators, including the zinc finger containing transcription factor Zac1 (zinc finger protein that regulates apoptosis and cell cycle arrest). Zac1 interacts with and enhances the activity of p53, thereby inducing cell cycle arrest and apoptosis. In this work, we use a gain-of-function assay in which mouse Zac1 (mZac1) is overexpressed in chicken retinal progenitor cells to study the effect on the final cell cycle of horizontal progenitor cells. The results showed that overexpression of mZac1 induced expression of p21 in a p53-dependent way and arrested the cell cycle as well as triggered apoptosis in chicken non-horizontal retinal progenitor cells. The negative regulation of the cell cycle by mZac1 is consistent with its proposed role as a tumour-suppressor gene. However, the horizontal cells were not affected by mZac1 overexpression. They progressed into S- and late G2/M-phase despite overexpression of mZac1. The inability of mZac1 to arrest the cell cycle in horizontal progenitor cells support the notion that the horizontal cells are less sensitive to events that triggers the p53 system during their terminal and neurogenic cell cycle, compared with other retinal cells. These properties are associated with a cell that has a propensity to become neoplastic and thus with a cell that may develop retinoblastoma.

  19. DUX4, a Candidate Gene for Facioscapulohumeral Muscular Dystrophy, Causes p53-Dependent Myopathy In Vivo

    PubMed Central

    Wallace, Lindsay M.; Garwick, Sara E.; Mei, Wenyan; Belayew, Alexandra; Coppee, Frederique; Ladner, Katherine J.; Guttridge, Denis; Yang, Jing; Harper, Scott Q.

    2014-01-01

    Objective Facioscapulohumeral muscular dystrophy (FSHD) is associated with D4Z4 repeat contraction on human chromosome 4q35. This genetic lesion does not result in complete loss or mutation of any gene. Consequently, the pathogenic mechanisms underlying FSHD have been difficult to discern. In leading FSHD pathogenesis models, D4Z4 contractions are proposed to cause epigenetic changes, which ultimately increase expression of genes with myopathic potential. Although no gene has been conclusively linked to FSHD development, recent evidence supports a role for the D4Z4-encoded DUX4 gene in FSHD. In this study, our objective was to test the in vivo myopathic potential of DUX4. Methods We delivered DUX4 to zebrafish and mouse muscle by transposon-mediated transgenesis and adeno-associated viral vectors, respectively. Results Overexpression of DUX4, which encodes a transcription factor, caused abnormalities associated with muscular dystrophy in zebrafish and mice. This toxicity required DNA binding, because a DUX4 DNA binding domain mutant produced no abnormalities. Importantly, we found the myopathic effects of DUX4 were p53 dependent, as p53 inhibition mitigated DUX4 toxicity in vitro, and muscles from p53 null mice were resistant to DUX4-induced damage. Interpretation Our work demonstrates the myopathic potential of DUX4 in animal muscle. Considering previous studies showed DUX4 was elevated in FSHD patient muscles, our data support the hypothesis that DUX4 overexpression contributes to FSHD development. Moreover, we provide a p53-dependent mechanism for DUX4 toxicity that is consistent with previous studies showing p53 pathway activation in FSHD muscles. Our work justifies further investigation of DUX4 and the p53 pathway in FSHD pathogenesis. PMID:21446026

  20. p53 inhibits DNA replication in vitro in a DNA-binding-dependent manner

    SciTech Connect

    Miller, S.D.; Farmer, G.; Prives, C.

    1995-12-01

    This report discusses new findings that the tumor supressor gene product p53 may play a role as a DNA-binding-dependent regulator of DNA replication. The results were obtained using polyomavirus in replication assays. Details regarding effects on cell growth arrest and transcriptional activation are discussed. 61 refs., 7 figs.

  1. Central role of mitochondria and p53 in PUVA-induced apoptosis in human keratinocytes cell line NCTC-2544

    SciTech Connect

    Viola, Giampietro Fortunato, Elena; Cecconet, Laura; Del Giudice, Laura; Dall'Acqua, Francesco; Basso, Giuseppe

    2008-02-15

    Despite strong evidence concerning the high efficiency of PUVA therapy (psoralen plus UVA light), its mechanism of action has not yet been fully elucidated. In this study, we have evaluated in a cell line of human keratinocytes (NCTC-2544) the effects of two linear psoralen derivatives, 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen (5-MOP), that are widely used in PUVA therapy and two angular derivatives, Angelicin (ANG) and 4,6,4'-trymetyl angelicin (TMA). All derivatives photoinduce cellular death, TMA being the most active compound. The cell cycle analysis showed that the four derivatives induce, 24 h after irradiation, a cell cycle arrest in G1 phase later followed by massive apoptosis. The G1 arrest is correlated to an increase in the expression of p21{sup Waf1/Cip1}, a protein associated with the cell cycle block and apoptosis. Furthermore, treatment of NCTC-2544 resulted in p53 activation by 5-MOP, 8-MOP, and ANG but not TMA and its phosphorylation at serine-15. The levels of p21{sup Waf1/Cip1} paralleled p53 protein staining pattern suggesting that p53 activation correlated with p21{sup Waf1/Cip1} induction. Simultaneous to p53 activation, psoralens induced mitochondrial depolarization, cytochrome c release, mitochondrial production of reactive oxygen species, as well as caspase-3 and -9 activation. Thus these results strongly indicate the necessity of p53 activation and the induction of the apoptotic machinery downstream of mitochondria.

  2. p53, Bcl-2 and cox-2 are involved in berberine hydrochloride-induced apoptosis of HeLa229 cells.

    PubMed

    Wang, Hai-Yan; Yu, Hai-Zhong; Huang, Sheng-Mou; Zheng, Yu-Lan

    2016-10-01

    The present study aimed to investigate the effects of berberine hydrochloride on the proliferation and apoptosis of HeLa229 human cervical cancer cells. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed to examine the cytotoxicity of berberine hydrochloride against HeLa229 cells. The effects of berberine hydrochloride on the apoptosis of HeLa229 cells was detected by immunofluorescence and flow cytometry, and the mRNA expression levels of p53, B‑cell lymphoma 2 (Bcl‑2) and cyclooxygenase‑2 (cox‑2) were analyzed by reverse transcription-quantitative polymerase chain reaction. Berberine hydrochloride inhibited the proliferation of HeLa229 cells in a dose‑dependent manner; minimum cell viability (3.61%) was detected following treatment with 215.164 µmol/l berberine hydrochloride and the half maximal inhibitory concentration value was 42.93 µmol/l following treatment for 72 h. In addition, berberine hydrochloride induced apoptosis in HeLa229 cells in a dose‑ and time‑dependent manner. Berberine hydrochloride upregulated the mRNA expression levels of p53, and downregulated mRNA expression levels of Bcl‑2 and cox‑2, in a dose‑dependent manner. In conclusion, berberine hydrochloride inhibited the proliferation and induced apoptosis of HeLa229 cells, potentially via the upregulation of p53 and the downregulation of Bcl‑2 and cox‑2 mRNA expression levels.

  3. Induction of Bex genes by curcumin is associated with apoptosis and activation of p53 in N2a neuroblastoma cells

    PubMed Central

    Sidhar, Himakshi; Giri, Ranjit K.

    2017-01-01

    Brain expressed X-linked (Bex) genes are newer group of pro-apoptotic genes. Role of any Bex gene in neuroblastoma and Bex4 and Bex6 in any cancer is completely unknown. Re-expression of all endogenous Bex genes by any nutraceutical is also unknown. Therefore, we investigated the induction of all endogenous Bex genes and associated mechanisms by curcumin using N2a, an aggressive neuroblastoma cell line. Curcumin induced all endogenous Bex genes prior to apoptosis in N2a cells in a dose- and time-dependent manner. Wortmannin (PI-3Kinases inhibitor), SP600125 (JNK inhibitor) and pifithrin-α (p53 inhibitor) abrogated curcumin-mediated induction of Bex genes. Inhibition of curcumin-mediated induction of Bex genes by pifithrin-α also inhibited N2a cells apoptosis suggesting, a direct role of Bex genes in N2a cells apoptosis and involvement of p53 in Bex genes induction. Curcumin treatment activated p53 through hyperphosphorylation at serine 15 before Bex genes induction indicating Bex genes are novel downstream targets of p53. Collectively, curcumin, a safe nutraceutical has the potential to induce all endogenous Bex genes to harness their anti-cancer properties in neuroblastoma cells. Re-expression of Bex genes by curcumin acts as tumor suppressors and may provide alternate strategy to treat neuroblastomas and other cancers with silenced Bex genes. PMID:28145533

  4. Induction of Bex genes by curcumin is associated with apoptosis and activation of p53 in N2a neuroblastoma cells.

    PubMed

    Sidhar, Himakshi; Giri, Ranjit K

    2017-02-01

    Brain expressed X-linked (Bex) genes are newer group of pro-apoptotic genes. Role of any Bex gene in neuroblastoma and Bex4 and Bex6 in any cancer is completely unknown. Re-expression of all endogenous Bex genes by any nutraceutical is also unknown. Therefore, we investigated the induction of all endogenous Bex genes and associated mechanisms by curcumin using N2a, an aggressive neuroblastoma cell line. Curcumin induced all endogenous Bex genes prior to apoptosis in N2a cells in a dose- and time-dependent manner. Wortmannin (PI-3Kinases inhibitor), SP600125 (JNK inhibitor) and pifithrin-α (p53 inhibitor) abrogated curcumin-mediated induction of Bex genes. Inhibition of curcumin-mediated induction of Bex genes by pifithrin-α also inhibited N2a cells apoptosis suggesting, a direct role of Bex genes in N2a cells apoptosis and involvement of p53 in Bex genes induction. Curcumin treatment activated p53 through hyperphosphorylation at serine 15 before Bex genes induction indicating Bex genes are novel downstream targets of p53. Collectively, curcumin, a safe nutraceutical has the potential to induce all endogenous Bex genes to harness their anti-cancer properties in neuroblastoma cells. Re-expression of Bex genes by curcumin acts as tumor suppressors and may provide alternate strategy to treat neuroblastomas and other cancers with silenced Bex genes.

  5. Effects of p53 on apoptosis and proliferation of hepatocellular carcinoma cells treated with transcatheter arterial chemoembolization

    PubMed Central

    Xiao, En-Hua; Li, Jing-Qing; Huang, Jie-Fu

    2004-01-01

    AIM: To evaluate the effects of p53 on apoptosis and proliferation of hepatocellular carcinoma (HCC) cells treated with transcatheter arterial chemoembolization (TACE). METHODS: A total of 136 patients with HCC received TACE and other management before surgery were divided into TACE group and non-TACE group. TACE group included 79 patients who had 1-5 courses of TACE before surgery, of them, 11 patients had 1-4 courses of chemotherapy (group A), 33 patients had 1-5 courses of chemotherapy combined with iodized oil (group B), 23 patients had 1-3 courses of chemotherapy, iodized oil and gelatin sponge (group C), 12 patients had 1-3 courses of chemotherapy combined with iodized oil, ethanol and gelatin sponge (group D). Non-TACE group included the remaining 57 patients who had surgery only. The extent of apoptosis was analyzed by transferase mediated dUTP nick end labeling (TUNEL) staining. The expressions of p53, Bcl-2, Bax, Ki-67 and PCNA protein were detected by immunohistochemical method. RESULTS: p53 protein expressions in trabecular and clear cells in HCC specimens were significantly lower than that in pseudoglandar, solid, poorly differentiated or undifferentiated and sclerosis HCC (P < 0.05). Expression of p53 protein in HCC cells increased with the increase of pathological grades (P < 0.05), and correlated positively with expressions of Ki-67 and PCNA protein, and negatively with Bcl-2 to Bax protein expression rate and AI (P < 0.05). Expression of p53 protein was significantly higher in group A than in groups B, C, D and the non-TACE group, and was higher in group B than in groups C and D, and lower in group D than in the non-TACE group (P < 0.05). CONCLUSION: Expression of p53 protein can enhance proliferation of HCC cells and suppress apoptosis of HCC cells after TACE. PMID:14716820

  6. Limited Role of Murine ATM in Oncogene-Induced Senescence and p53-Dependent Tumor Suppression

    PubMed Central

    Martinez-Pastor, Barbara; Ortega-Molina, Ana; Soria, Rebeca; Collado, Manuel; Fernandez-Capetillo, Oscar; Serrano, Manuel

    2009-01-01

    Recent studies in human fibroblasts have provided a new general paradigm of tumor suppression according to which oncogenic signaling produces DNA damage and this, in turn, results in ATM/p53-dependent cellular senescence. Here, we have tested this model in a variety of murine experimental systems. Overexpression of oncogenic Ras in murine fibroblasts efficiently induced senescence but this occurred in the absence of detectable DNA damage signaling, thus suggesting a fundamental difference between human and murine cells. Moreover, lung adenomas initiated by endogenous levels of oncogenic K-Ras presented abundant senescent cells, but undetectable DNA damage signaling. Accordingly, K-Ras-driven adenomas were also senescent in Atm-null mice, and the tumorigenic progression of these lesions was only modestly accelerated by Atm-deficiency. Finally, we have examined chemically-induced fibrosarcomas, which possess a persistently activated DNA damage response and are highly sensitive to the activity of p53. We found that the absence of Atm favored genomic instability in the resulting tumors, but did not affect the persistent DNA damage response and did not impair p53-dependent tumor suppression. All together, we conclude that oncogene-induced senescence in mice may occur in the absence of a detectable DNA damage response. Regarding murine Atm, our data suggest that it plays a minor role in oncogene-induced senescence or in p53-dependent tumor suppression, being its tumor suppressive activity probably limited to the maintenance of genomic stability. PMID:19421407

  7. Treatment with a BH3 mimetic overcomes the resistance of latency III EBV (+) cells to p53-mediated apoptosis

    PubMed Central

    Pujals, A; Renouf, B; Robert, A; Chelouah, S; Hollville, É; Wiels, J

    2011-01-01

    P53 inactivation is often observed in Burkitt's lymphoma (BL) cells due to mutations in the p53 gene or overexpression of its negative regulator, murine double minute-2 (MDM2). This event is now considered an essential part of the oncogenic process. Epstein–Barr virus (EBV) is strongly associated with BL and is a cofactor in its development. We previously showed that nutlin-3, an antagonist of MDM2, activates the p53 pathway in BL cell lines harboring wild-type p53. However, nutlin-3 strongly induced apoptosis in EBV (−) or latency I EBV (+) cells, whereas latency III EBV (+) cells were much more resistant. We show here that this resistance to apoptosis is also observed in latency III EBV (+) lymphoblastoid cell lines. We also show that, in latency III EBV (+) cells, B-cell lymphona 2 (Bcl-2) is selectively overproduced and interacts with Bcl-2-associated X protein (Bax), preventing its activation. The treatment of these cells with the Bcl-2-homology domain 3 mimetic ABT-737 disrupts Bax/Bcl-2 interaction and allows Bax activation by nutlin-3. Furthermore, treatment with these two compounds strongly induces apoptosis. Thus, a combination of Mdm2 and Bcl-2 inhibitors might be a useful anti-cancer strategy for diseases linked to EBV infection. PMID:21796156

  8. Treatment with a BH3 mimetic overcomes the resistance of latency III EBV (+) cells to p53-mediated apoptosis.

    PubMed

    Pujals, A; Renouf, B; Robert, A; Chelouah, S; Hollville, E; Wiels, J

    2011-07-28

    P53 inactivation is often observed in Burkitt's lymphoma (BL) cells due to mutations in the p53 gene or overexpression of its negative regulator, murine double minute-2 (MDM2). This event is now considered an essential part of the oncogenic process. Epstein-Barr virus (EBV) is strongly associated with BL and is a cofactor in its development. We previously showed that nutlin-3, an antagonist of MDM2, activates the p53 pathway in BL cell lines harboring wild-type p53. However, nutlin-3 strongly induced apoptosis in EBV (-) or latency I EBV (+) cells, whereas latency III EBV (+) cells were much more resistant. We show here that this resistance to apoptosis is also observed in latency III EBV (+) lymphoblastoid cell lines. We also show that, in latency III EBV (+) cells, B-cell lymphona 2 (Bcl-2) is selectively overproduced and interacts with Bcl-2-associated X protein (Bax), preventing its activation. The treatment of these cells with the Bcl-2-homology domain 3 mimetic ABT-737 disrupts Bax/Bcl-2 interaction and allows Bax activation by nutlin-3. Furthermore, treatment with these two compounds strongly induces apoptosis. Thus, a combination of Mdm2 and Bcl-2 inhibitors might be a useful anti-cancer strategy for diseases linked to EBV infection.

  9. Regulation of p53 tetramerization and nuclear export by ARC

    PubMed Central

    Foo, Roger S.-Y.; Nam, Young-Jae; Ostreicher, Marc Jason; Metzl, Mark D.; Whelan, Russell S.; Peng, Chang-Fu; Ashton, Anthony W.; Fu, Weimin; Mani, Kartik; Chin, Suet-Feung; Provenzano, Elena; Ellis, Ian; Figg, Nichola; Pinder, Sarah; Bennett, Martin R.; Caldas, Carlos; Kitsis, Richard N.

    2007-01-01

    Inactivation of the transcription factor p53 is central to carcinogenesis. Yet only approximately one-half of cancers have p53 loss-of-function mutations. Here, we demonstrate a mechanism for p53 inactivation by apoptosis repressor with caspase recruitment domain (ARC), a protein induced in multiple cancer cells. The direct binding in the nucleus of ARC to the p53 tetramerization domain inhibits p53 tetramerization. This exposes a nuclear export signal in p53, triggering Crm1-dependent relocation of p53 to the cytoplasm. Knockdown of endogenous ARC in breast cancer cells results in spontaneous tetramerization of endogenous p53, accumulation of p53 in the nucleus, and activation of endogenous p53 target genes. In primary human breast cancers with nuclear ARC, p53 is almost always WT. Conversely, nearly all breast cancers with mutant p53 lack nuclear ARC. We conclude that nuclear ARC is induced in cancer cells and negatively regulates p53. PMID:18087040

  10. Nano-SiO2 induces apoptosis via activation of p53 and Bax mediated by oxidative stress in human hepatic cell line.

    PubMed

    Ye, Yiyi; Liu, Jianwen; Xu, Jianhe; Sun, Lijuan; Chen, Mingcang; Lan, Minbo

    2010-04-01

    Nanoparticles such as nano-SiO(2) are increasingly used in food, cosmetics, diagnosis, imaging and drug delivery. However, toxicological data of nano-SiO(2) on hepatic cells in vitro and their detailed molecular mechanisms still remain unclear. In order to assess toxicity of nano-SiO(2), L-02 cells were exposed to 0.2, 0.4 and 0.6 mg/ml of SiO(2) colloids (21, 48 and 86 nm) for 12, 24, 36 and 48h. Lactate dehydrogenase released from damaged cells were quantified, cellular ultrastructural organization was observed, and the levels of reactive oxygen species (ROS), lipid peroxidation and glutathione were measured. Apoptosis induced by 21 nm SiO(2) was characterized by annexin V-FITC/PI staining and DNA ladder assay. Furthermore, apoptosis related proteins such as p53, Bax and Bcl-2 were analyzed by using western blot analysis. Our data indicated that nano-SiO(2) caused cytotoxicity in size, dose and time dependent manners. Oxidative stress and apoptosis were induced by exposure to 21 nm SiO(2). Moreover, the expression of p53 and Bax was increased in time and dose dependent patterns, whereas the expression of Bcl-2 was not significantly changed. In conclusion, ROS-mediated oxidative stress, the activation of p53 and up-regulation of Bax/Bcl-2 ratio are involved in mechanistic pathways of 21 nm SiO(2) induced apoptosis in L-02 cells.

  11. Trigonella foenum (Fenugreek) Induced Apoptosis in Hepatocellular Carcinoma Cell Line, HepG2, Mediated by Upregulation of p53 and Proliferating Cell Nuclear Antigen

    PubMed Central

    Khalil, Mahmoud I. M.; Ibrahim, Mohamed M.; El-Gaaly, Gehan A.; Sultan, Ahmed S.

    2015-01-01

    Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and most current therapies are of limited efficacy. Trigonella foenum (Fenugreek) is a traditional herbal plant with antitumor activity, although the mechanisms of its activity remain unclear. Herein, a crude methanol extract was prepared from Fenugreek seeds (FCE) and its anticancer mechanism was evaluated, using HepG2 cell line. Growth-inhibitory effect and apoptosis induction of HepG2 cells were evidenced by MTT assay, cell morphology alteration, apoptosis enzyme-linked immunosorbent assay, flow cytometric analysis, caspase-3 activity, and expression of p53, proapoptotic protein, Bax, and proliferating cell nuclear antigen (PCNA) after (100∼500 μg/mL) FCE treatment for 48 h. Furthermore, FCE was analyzed by Chromatography-Mass Spectrometry (GC/MS). Our results revealed that FCE treatment for 48 h showed a cytotoxic effect and apoptosis induction in a dose-dependent manner that was mediated by upregulation of p53, Bax, PCNA, and caspase-3 activation in HepG2 cells. GC-MS analysis of FCE showed the presence of fourteen bioactive compounds such as Terpenoids and Flavonoids, including two main constituents with anticancer activity, Squalene and Naringenin (27.71% and 24.05%), respectively. Our data introduced FCE as a promising nontoxic herbal with therapeutic potential to induce apoptosis in HepG2 cells through p53, Bax, and PCNA upregulation in caspase-3 dependent manner. PMID:26557712

  12. Zerumbone, a Southeast Asian Ginger Sesquiterpene, Induced Apoptosis of Pancreatic Carcinoma Cells through p53 Signaling Pathway

    PubMed Central

    Zhang, Songyan; Liu, Qiaojing; Liu, Yanju; Qiao, Hong; Liu, Yu

    2012-01-01

    Pancreatic carcinoma is one common cancer with gradually increasing incidence during the past several decades. However, currently the candidate drugs to suppress pancreatic cancer remain lacking. This research was carried out to investigate if zerumbone, a natural cyclic sesquiterpene isolated from Zingiber zerumbet Smith, will produce the anticancer effects on pancreatic carcinoma cell lines. The results showed that zerumbone concentration, and time, dependently produced inhibitory actions on cell viability of PANC-1 cells. In addition, Hoechst 33342, AO/EB, TUNEL staining, and caspase-3 activity assay further showed that zerumbone induced apoptosis of PANC-1 cells. The expression of p53 protein was markedly upregulated, and the p21 level was also obviously elevated in zerumbone-treated PANC-1 cells. Moreover, ROS production was increased by about 149% in PANC-1 cells treated by zerumbone 30 μM. Zerumbone also produced the same antitumor activity in pancreatic carcinoma cell lines SW1990 and AsPC-1. In summary, we found that zerumbone was able to induce apoptosis of pancreatic carcinoma cell lines, indicating to be a promising treatment for pancreatic cancer. PMID:22454691

  13. Compensatory Proliferation in Drosophila Imaginal Discs Requires Dronc-Dependent p53 Activity

    PubMed Central

    Wells, Brent S.; Yoshida, Eri; Johnston*, Laura A.

    2006-01-01

    Summary Background The p53 transcription factor directs a transcriptional program that determines whether a cell lives or dies after DNA damage. Animal survival after extensive cellular damage often requires that lost tissue be replaced through compensatory growth or regeneration. In Drosophila, damaged imaginal disc cells can induce the proliferation of neighboring viable cells, but how this is controlled is not clear. Here we provide evidence that Drosophila p53 (dp53) has a previously unidentified role in coordinating the compensatory growth response to tissue damage. Results We find that dp53, the sole p53 ortholog in Drosophila, is required for each component of the response to cellular damage, including two separate cell-cycle arrests, changes in patterning gene expression, cell proliferation, and growth. We demonstrate that these processes are regulated by dp53 in a manner that is independent of DNA-damage sensing but that requires the initiator caspase Dronc. Our results indicate that once induced, dp53 amplifies and sustains the response through a positive feedback loop with Dronc and the apoptosis-inducing factors Hid and Reaper. Conclusions How cell death and cell proliferation are coordinated during development and after stress is a fundamental question that is critical for an understanding of growth regulation. Our data suggest that dp53 may carry out an ancestral function that promotes animal survival through the coordination of responses leading to compensatory growth after tissue damage. PMID:16920621

  14. T cells from baxalpha transgenic mice show accelerated apoptosis in response to stimuli but do not show restored DNA damage-induced cell death in the absence of p53.

    PubMed Central

    Brady, H J; Salomons, G S; Bobeldijk, R C; Berns, A J

    1996-01-01

    Baxalpha was isolated due to its interaction with Bcl-2. Baxalpha overexpression in an interleukin (IL)-3 dependent cell line accelerates apoptosis upon removal of the cytokine. The ratio of Baxalpha to Bcl-2 appears to be crucial for the effect. To study the action of the bax gene product in vivo, we have generated transgenic mice overexpressing Baxalpha specifically in T cells. Such T cells show accelerated apoptosis in response to gamma-radiation, dexamethasone and etoposide. By crossing baxalpha mice with bcl-2 transgenics we show that the critical nature of the Baxalpha:Bcl-2 ratio holds in primary T cells and that it can be manipulated to elicit a strong response to previously resisted stimuli. p53 has a role in the regulation of apoptosis in response to DNA-damaging agents. p53 directly activates transcription of the bax gene. The presence of the baxalpha transgene accelerated apoptosis in thymocytes from both p53-l- and p53+l- mice in response to dexamethasone. Thymocytes from p53-l- mice with the baxalpha transgene showed similar resistance to apoptosis by DNA-damaging agents as did p53-l- mice without the transgene. Baxalpha overexpression alone cannot restore the DNA damage apoptosis pathway, suggesting that p53 is required to induce or activate other factor(s) to reconstitute the response fully. Images PMID:8635454

  15. HZE particle radiation induces tissue-specific and p53-dependent mutagenesis in transgenic animals

    NASA Technical Reports Server (NTRS)

    Chang, P. Y.; Kanazawa, N.; Lutze-Mann, L.; Winegar, R.

    2001-01-01

    Transgenic animals, with the integrated target gene, provide a unique approach for measuring and characterizing mutations in any tissue of the animal. We are using the plasmid-based lacZ transgenic mice with different p53 genetic background to examine radiation-induced genetic damage resulting from exposure to heavy particle radiation. We measured lacZ mutation frequencies (MF) in the brain and spleen tissues at various times after exposing animals to an acute dose of 1 Gy of 1GeV/amu iron particles. MF in the spleen of p53+/+ animals increased up to 2.6-fold above spontaneous levels at 8 weeks post irradiation. In contrast, brain MF from the same animals increased 1.7-fold above controls in the same period. In the p53-/- animals, brain MF increased to 2.2-fold above spontaneous levels at 1 week after treatment, but returned to control levels thereafter. Radiation also induced alterations in the spectrum of mutants in both tissues, accompanied by changes in the frequency of mutants with deletions extending past the transgene into mouse genomic DNA. Our results indicate that the accumulation of transgene MF after radiation exposure is dependant on the tissue examined as well as the p53 genetic background of the animals.

  16. The nucleoprotein of influenza A virus induces p53 signaling and apoptosis via attenuation of host ubiquitin ligase RNF43

    PubMed Central

    Nailwal, H; Sharma, S; Mayank, A K; Lal, S K

    2015-01-01

    The interplay between influenza virus and host factors to support the viral life cycle is well documented. Influenza A virus (IAV) proteins interact with an array of cellular proteins and hijack host pathways which are at the helm of cellular responses to facilitate virus invasion. The multifaceted nature of the ubiquitination pathway for protein regulation makes it a vulnerable target of many viruses including IAV. To this end we conducted a yeast two-hybrid screen to search for cellular ubiquitin ligases important for influenza virus replication. We identified host protein, RING finger protein 43 (RNF43), a RING-type E3 ubiquitin ligase, as a novel interactor of nucleoprotein (NP) of IAV and an essential partner to induce NP-driven p53-mediated apoptosis in IAV-infected cells. In this study, we demonstrate that IAV leads to attenuation of RNF43 transcripts and hence its respective protein levels in the cellular milieu whereas in RNF43 depleted cells, viral replication was escalated several folds. Moreover, RNF43 polyubiquitinates p53 which further leads to its destabilization resulting in a decrease in induction of the p53 apoptotic pathway, a hitherto unknown process targeted by NP for p53 stabilization and accumulation. Collectively, these results conclude that NP targets RNF43 to modulate p53 ubiquitination levels and hence causes p53 stabilization which is conducive to an enhanced apoptosis level in the host cells. In conclusion, our study unravels a novel strategy adopted by IAV for utilizing the much conserved ubiquitin proteasomal pathway. PMID:25996295

  17. Free radical scavenger edaravone suppresses x-ray-induced apoptosis through p53 inhibition in MOLT-4 cells.

    PubMed

    Sasano, Nakashi; Enomoto, Atsushi; Hosoi, Yoshio; Katsumura, Yosuke; Matsumoto, Yoshihisa; Shiraishi, Kenshiro; Miyagawa, Kiyoshi; Igaki, Hiroshi; Nakagawa, Keiichi

    2007-11-01

    Edaravone, a clinical drug used widely for the treatment of acute cerebral infarction, is reported to scavenge free radicals. In the present study, we investigated the radioprotective effect of edaravone on X-ray-induced apoptosis in MOLT-4 cells. Apoptosis was determined by the dye exclusion test, Annexin V binding assay, cleavage of caspase, and DNA fragmentation. We found that edaravone significantly suppressed the X-ray-induced apoptosis. The amount of intracellular ROS production was determined by the chloromethyl-2',7'-dichlorodihydro-fluorescein diacetate system. We found that the intracellular ROS production by X-irradiation was completely suppressed by the addition of edaravone. The accumulation and phosphorylation of p53 and the expression of p21(WAF1), a target protein of p53, which were induced by X-irradiation, were also suppressed by adding edaravone. We conclude that the free radical scavenger edaravone suppresses X-ray-induced apoptosis in MOLT-4 cells by inhibiting p53.

  18. Arenobufagin activates p53 to trigger esophageal squamous cell carcinoma cell apoptosis in vitro and in vivo

    PubMed Central

    Lv, Junhong; Lin, Shaohuan; Peng, Panli; Cai, Changqing; Deng, Jianming; Wang, Mingzhi; Li, Xuejun; Lin, Rongsheng; Lin, Yu; Fang, Ailing; Li, Qiling

    2017-01-01

    Esophageal squamous cell carcinoma (ESCC) is often diagnosed at late incurable stage and lacks effective treatment strategy. Bufadienolides are cardiotonic steroids isolated from the skin and parotid venom glands of the toad Bufo bufo gargarizans Cantor with novel anticancer activity. However, there is little information about the effects and action mechanisms of bufadienolides on ESCC cells. In this study, the in vitro and in vivo anti-ESCC activities of bufadienolides, including bufalin (Bu) and arenobufagin (ArBu), were examined and the underlying molecular mechanisms were elucidated. The results showed that ArBu exhibited higher anticancer efficacy than Bu against a panel of five ESCC cells, with IC50 values ranging from 0.8 μM to 3.6 μM. However, ArBu showed lower toxicity toward Het-1A human normal esophageal squamous cells, indicating its great selectivity between cancer and normal cells. Moreover, ArBu effectively induced ESCC cell apoptosis mainly by triggering caspase activation through intrinsic and extrinsic pathways. Treatment of ESCC cells also significantly activated p53 signaling by enhancing its phosphorylation. Interestingly, transfection of cells with p53 small interfering RNA significantly inhibited the ArBu-induced p53 phosphorylation and the overall apoptotic cell death. Furthermore, ArBu also demonstrated novel in vivo anticancer efficacy by inhibiting the tumor growth through activation of p53 pathway. Taken together, these results demonstrate the p53-targeting therapeutic potential of bufadienolides against ESCC. PMID:28280360

  19. Endogenous c-Myc is essential for p53-induced apoptosis in response to DNA damage in vivo.

    PubMed

    Phesse, T J; Myant, K B; Cole, A M; Ridgway, R A; Pearson, H; Muncan, V; van den Brink, G R; Vousden, K H; Sears, R; Vassilev, L T; Clarke, A R; Sansom, O J

    2014-06-01

    Recent studies have suggested that C-MYC may be an excellent therapeutic cancer target and a number of new agents targeting C-MYC are in preclinical development. Given most therapeutic regimes would combine C-MYC inhibition with genotoxic damage, it is important to assess the importance of C-MYC function for DNA damage signalling in vivo. In this study, we have conditionally deleted the c-Myc gene in the adult murine intestine and investigated the apoptotic response of intestinal enterocytes to DNA damage. Remarkably, c-Myc deletion completely abrogated the immediate wave of apoptosis following both ionizing irradiation and cisplatin treatment, recapitulating the phenotype of p53 deficiency in the intestine. Consistent with this, c-Myc-deficient intestinal enterocytes did not upregulate p53. Mechanistically, this was linked to an upregulation of the E3 Ubiquitin ligase Mdm2, which targets p53 for degradation in c-Myc-deficient intestinal enterocytes. Further, low level overexpression of c-Myc, which does not impact on basal levels of apoptosis, elicited sustained apoptosis in response to DNA damage, suggesting c-Myc activity acts as a crucial cell survival rheostat following DNA damage. We also identify the importance of MYC during DNA damage-induced apoptosis in several other tissues, including the thymus and spleen, using systemic deletion of c-Myc throughout the adult mouse. Together, we have elucidated for the first time in vivo an essential role for endogenous c-Myc in signalling DNA damage-induced apoptosis through the control of the p53 tumour suppressor protein.

  20. Pathways connecting telomeres and p53 in senescence, apoptosis, and cancer

    SciTech Connect

    Artandi, Steven E. . E-mail: sartandi@stanford.edu; Attardi, Laura D. . E-mail: attardi@stanford.edu

    2005-06-10

    The ends of eukaryotic chromosomes are protected by specialized structures termed telomeres that serve in part to prevent the chromosome end from activating a DNA damage response. However, this important function for telomeres in chromosome end protection can be lost as telomeres shorten with cell division in culture or in self-renewing tissues with advancing age. Impaired telomere function leads to induction of a DNA damage response and activation of the tumor suppressor protein p53. p53 serves a critical role in enforcing both senescence and apoptotic responses to dysfunctional telomeres. Loss of p53 creates a permissive environment in which critically short telomeres are inappropriately joined to generate chromosomal end-to-end fusions. These fused chromosomes result in cycles of chromosome fusion-bridge-breakage, which can fuel cancer initiation, especially in epithelial tissues, by facilitating changes in gene copy number.

  1. Radiation-induced p53 protein response in the A549 cell line is culture growth-phase dependent

    SciTech Connect

    Johnson, N.F.; Gurule, D.M.; Carpenter, T.R.

    1995-12-01

    One role of the p53 tumor suppressor protein has been recently revealed. Kastan, M.B. reported that p53 protein accumulates in cells exposed to ionizing radiation. The accumulation of p53 protein is in response to DNA damage, most importantly double-strand breaks, that results from exposure to ionizing radiation. The rise in cellular p53 levels is necessary for an arrest in the G{sub 1} phase of the cell cycle to provide additional time for DNA repair. The p53 response has also been demonstrated to enhance PCNA-dependent repair. p53 is thus an important regulator of the cellular response to DNA-damaging radiation. From this data, it can be concluded that the magnitude of the p53 response is not dependent on the phase of culture growth.

  2. Pleurotus ostreatus inhibits proliferation of human breast and colon cancer cells through p53-dependent as well as p53-independent pathway

    PubMed Central

    JEDINAK, ANDREJ; SLIVA, DANIEL

    2009-01-01

    In spite of the global consumption of mushrooms, only two epidemiological studies demonstrated an inverse correlation between mushroom intake and the risk of cancer. Therefore, in the present study we evaluated whether extracts from edible mushrooms Agaricus bisporus (portabella), Flammulina velutipes (enoki), Lentinula edodes (shiitake) and Pleurotus ostreatus (oyster) affect the growth of breast and colon cancer cells. Here, we identified as the most potent, P. ostreatus (oyster mushroom) which suppressed proliferation of breast cancer (MCF-7, MDA-MB-231) and colon cancer (HT-29, HCT-116) cells, without affecting proliferation of epithelial mammary MCF-10A and normal colon FHC cells. Flow cytometry revealed that the inhibition of cell proliferation by P. ostreatus was associated with the cell cycle arrest at G0/G1 phase in MCF-7 and HT-29 cells. Moreover, P. ostreatus induced the expression of the tumor suppressor p53 and cyclin-dependent kinase inhibitor p21(CIP1/WAF1), whereas inhibited the phosphorylation of retinoblastoma Rb protein in MCF-7 cells. In addition, P. ostreatus also up-regulated expression of p21 and inhibited Rb phosphorylation in HT-29 cells, suggesting that that P. ostreatus suppresses the proliferation of breast and colon cancer cells via p53-dependent as well as p53-independent pathway. In conclusion, our results indicated that the edible oyster mushroom has potential therapeutic/preventive effects on breast and colon cancer. PMID:19020765

  3. The double benefit of Spalax p53: surviving underground hypoxia while defying lung cancer cells in vitro via autophagy and caspase-dependent cell death

    PubMed Central

    Ellis, Martin; Stern, Orly; Ashur-Fabian, Osnat

    2016-01-01

    The blind subterranean mole rat, Spalax ehrenbergi, is a model organism for hypoxia tolerance. This superspecies have adapted to severe environment by altering an array of hypoxia-mediated genes, among which an alteration in the p53 DNA binding domain (corresponding to R174K in humans) that hinders its transcriptional activity towards apoptotic genes. It is well accepted that apoptosis is not the only form of programmed cell death and that mechanisms that depend on autophagy are also involved. In the current work we have extended our research and investigated the possibility that Spalax p53 can activate autophagy. Using two complementary assays, we have established that over-expression of the Spalax p53 in p53-null cells (human lung cancer cells, H1299), potently induces autophagy. As Spalax is considered highly resistant to cancer, we further studied the relative contribution of autophagy on the outcome of H1299 cells, following transfection with Spalax p53. Results indicate that Spalax p53 acts as a tumor suppressor in lung cancer cells, inducing cell death that involves autophagy and caspases and inhibiting cell number, which is exclusively caspase-dependent. To conclude, the Spalax p53 protein was evolutionary adapted to survive severe underground hypoxia while retaining the ability to defy lung cancer. PMID:27557517

  4. Crocetin exploits p53-induced death domain (PIDD) and FAS-associated death domain (FADD) proteins to induce apoptosis in colorectal cancer

    PubMed Central

    Ray, Pallab; Guha, Deblina; Chakraborty, Juni; Banerjee, Shuvomoy; Adhikary, Arghya; Chakraborty, Samik; Das, Tanya; Sa, Gaurisankar

    2016-01-01

    Tumor suppressor p53 preserves the genomic integrity by restricting anomaly at the gene level. The hotspots for mutation in half of all colon cancers reside in p53. Hence, in a p53-mutated cellular milieu targeting cancer cells may be achievable by targeting the paralogue(s) of p53. Here we have shown the effectiveness of crocetin, a dietary component, in inducing apoptosis of colon cancer cells with varying p53 status. In wild-type p53-expressing cancer cells, p53 in one hand transactivates BAX and in parallel up-regulates p53-induced death domain protein (PIDD) that in turn cleaves and activates BID through caspase-2. Both BAX and t-BID converge at mitochondria to alter the transmembrane potential thereby leading to caspase-9 and caspase-3-mediated apoptosis. In contrast, in functional p53-impaired cells, this phytochemical exploits p53-paralogue p73, which up-regulates FAS to cleave BID through FAS-FADD-caspase-8-pathway. These findings not only underline the phenomenon of functional switch-over from p53 to p73 in p53-impaired condition, but also validate p73 as a promising and potential target for cancer therapy in absence of functional p53. PMID:27622714

  5. Profiling dose-dependent activation of p53-mediated signaling pathways by chemicals with distinct mechanisms of DNA damage.

    PubMed

    Clewell, Rebecca A; Sun, Bin; Adeleye, Yeyejide; Carmichael, Paul; Efremenko, Alina; McMullen, Patrick D; Pendse, Salil; Trask, O J; White, Andy; Andersen, Melvin E

    2014-11-01

    As part of a larger effort to provide proof-of-concept in vitro-only risk assessments, we have developed a suite of high-throughput assays for key readouts in the p53 DNA damage response toxicity pathway: double-strand break DNA damage (p-H2AX), permanent chromosomal damage (micronuclei), p53 activation, p53 transcriptional activity, and cell fate (cell cycle arrest, apoptosis, micronuclei). Dose-response studies were performed with these protein and cell fate assays, together with whole genome transcriptomics, for three prototype chemicals: etoposide, quercetin, and methyl methanesulfonate. Data were collected in a human cell line expressing wild-type p53 (HT1080) and results were confirmed in a second p53 competent cell line (HCT 116). At chemical concentrations causing similar increases in p53 protein expression, p53-mediated protein expression and cellular processes showed substantial chemical-specific differences. These chemical-specific differences in the p53 transcriptional response appear to be determined by augmentation of the p53 response by co-regulators. More importantly, dose-response data for each of the chemicals indicate that the p53 transcriptional response does not prevent micronuclei induction at low concentrations. In fact, the no observed effect levels and benchmark doses for micronuclei induction were less than or equal to those for p53-mediated gene transcription regardless of the test chemical, indicating that p53's post-translational responses may be more important than transcriptional activation in the response to low dose DNA damage. This effort demonstrates the process of defining key assays required for a pathway-based, in vitro-only risk assessment, using the p53-mediated DNA damage response pathway as a prototype.

  6. Mitochondrially targeted wild-type p53 induces apoptosis in a solid human tumor xenograft model

    PubMed Central

    Palacios, Gustavo; Crawford, Howard C.; Vaseva, Angelina; Moll, Ute M.

    2013-01-01

    Classic but also novel roles of p53 are becoming increasingly well characterized. We previously showed that ex vivo retroviral transfer of mitochondrially targeted wild type p53 (mitop53) in the Eμ-myc mouse lymphoma model efficiently induces tumor cell killing in vivo. In an effort to further explore the therapeutic potential of mitop53 for its pro-apoptotic effect in solid tumors, we generated replication-deficient recombinant human Adenovirus type 5 vectors. We show here that adenoviral delivery of mitop53 by intratumoral injection into HCT116 human colon carcinoma xenograft tumors in nude mice is surprisingly effective, resulting in tumor cell death of comparable potency to conventional p53. These apoptotic effects in vivo were confirmed by Ad5-mitop53 mediated cell death of HCT116 cells in culture. Together, these data provide encouragement to further explore the potential for novel mitop53 proteins in cancer therapy to execute the shortest known circuitry of p53 death signaling. PMID:18719383

  7. Characterization of the molecular mechanisms for p53-mediated differentiation.

    PubMed

    Chylicki, K; Ehinger, M; Svedberg, H; Gullberg, U

    2000-11-01

    The p53 tumor suppressor protein can induce both apoptosis and cell cycle arrest. Moreover, we and others have shown previously that p53 is a potent mediator of differentiation. For example, expression of ptsp53, a temperature-inducible form of p53, induces differentiation of leukemic monoblastic U-937 cells. The functions of p53 have for long been believed to be dependent on the transactivating capacity of p53. However, recent data show that both p53-induced cell cycle arrest and apoptosis can be induced independently of p53-mediated transcriptional activation, indicating alternative pathways for p53-induced apoptosis and cell cycle arrest. The bcl-2 proto-oncogene contributes to the development of certain malignancies, probably by inhibition of apoptosis. Interestingly, Bcl-2 has been shown to inhibit p53-mediated apoptosis as well as p53-mediated transcriptional activation. Asking whether Bcl-2 would interfere with the p53-mediated differentiation of U-937 cells, we stably transfected bcl-2 to U-937 cells inducibly expressing p53. Although the established Bcl-2-expressing clones were resistant to p53-mediated apoptosis, we did not observe any interference of Bcl-2 with the p53-mediated differentiation, suggesting separable pathways for p53 in mediating apoptosis and differentiation of U-937 cells. Neither did expression of Bcl-2 interfere with p53-induced expression of endogenous p21, suggesting that p53-induced differentiation might be dependent on the transcriptional activity of p53. To further investigate whether the p53-mediated differentiation of U-937 cells depends on the transcriptional activity of p53, we overexpressed transactivation-deficient p53, a transcriptionally inactive p53 mutant in these cells. However, in contrast to the effects of wild-type p53, expression of trans-activation-deficient p53 did neither induce signs of apoptosis nor of differentiation in U-937 cells. Our results indicate that the transcriptional activity of p53 is essential

  8. Identification of p53 in mitochondria.

    PubMed

    Vaseva, Angelina V; Moll, Ute M

    2013-01-01

    p53 is a master regulator of cell death pathways and has transcription-dependent and transcription-independent modes of action. Mitochondria are major signal transducers in apoptosis and are critical for p53-dependent cell death. Our lab and others have discovered that a fraction of stress-induced wild-type p53 protein rapidly translocates to mitochondria upon various stress stimuli and exerts p53-dependent apoptosis. Suborganellar localization by various methods shows that p53 localizes to the surface of mitochondria. Direct targeting of p53 to mitochondria is sufficient to induce apoptosis in p53-null cells, without requiring further DNA damage. Recently, p53 has been also shown to localize to other mitochondrial compartments such as the mitochondrial matrix where it plays a role in maintaining mitochondrial genome integrity. Here, we describe subcellular fractionation as a classic technique for detecting mitochondrial p53 in cell extracts. It consists of cell homogenization by hypo-osmotic swelling, removal of nuclear components by low-speed centrifugation, and mitochondrial isolation by a discontinuous sucrose density gradient. Additionally, we describe a method for submitochondrial fractionation, performed by phosphate buffer mediated swelling/shrinking. p53 and other mitochondrial proteins can then be detected by standard immunoblotting procedures. The quality of mitochondrial isolates/subfractions can be verified for purity and intactness.

  9. Mitotic Catastrophe Occurs in the Absence of Apoptosis in p53-Null Cells with a Defective G1 Checkpoint

    PubMed Central

    Fragkos, Michalis; Beard, Peter

    2011-01-01

    Cell death occurring during mitosis, or mitotic catastrophe, often takes place in conjunction with apoptosis, but the conditions in which mitotic catastrophe may exhibit features of programmed cell death are still unclear. In the work presented here, we studied mitotic cell death by making use of a UV-inactivated parvovirus (adeno-associated virus; AAV) that has been shown to induce a DNA damage response and subsequent death of p53-defective cells in mitosis, without affecting the integrity of the host genome. Osteosarcoma cells (U2OSp53DD) that are deficient in p53 and lack the G1 cell cycle checkpoint respond to AAV infection through a transient G2 arrest. We found that the infected U2OSp53DD cells died through mitotic catastrophe with no signs of chromosome condensation or DNA fragmentation. Moreover, cell death was independent of caspases, apoptosis-inducing factor (AIF), autophagy and necroptosis. These findings were confirmed by time-lapse microscopy of cellular morphology following AAV infection. The assays used readily revealed apoptosis in other cell types when it was indeed occurring. Taken together the results indicate that in the absence of the G1 checkpoint, mitotic catastrophe occurs in these p53-null cells predominantly as a result of mechanical disruption induced by centrosome overduplication, and not as a consequence of a suicide signal. PMID:21853057

  10. The Antioxidative Fraction of White Mulberry Induces Apoptosis through Regulation of p53 and NFκB in EAC Cells

    PubMed Central

    Khan, Muhammad Ali; Kabir, Syed Rashel; Reza, Md Abu; Rahman, Md Mahbubur; Islam, Mohammad Saiful; Rahman, Md Aziz Abdur; Rashid, Mamunur; Sadik, Md Golam

    2016-01-01

    In this study, the antioxidative fraction of white mulberry (Morus alba) was found to have an apotogenic effect on Ehrlich’s ascites carcinoma cell-induced mice (EAC mice) that correlate with upregulated p53 and downregulated NFκB signaling. The antioxidant activities and polyphenolic contents of various mulberry fractions were evaluated by spectrophotometry and the ethyl acetate fraction (EAF) was selected for further analysis. Strikingly, the EAF caused 70.20% tumor growth inhibition with S-phase cell cycle arrest, normalized blood parameters including red/white blood cell counts and suppressed the tumor weight of EAC mice compared with untreated controls. Fluorescence microscopy analysis of EAF-treated EAC cells revealed DNA fragmentation, cell shrinkage, and plasma membrane blebbing. These characteristic morphological features of apoptosis influenced us to further investigate pro- and anti-apoptotic signals in EAF-treated EAC mice. Interestingly, apoptosis correlated with the upregulation of p53 and its target genes PARP-1 and Bax, and also with the down-regulation of NFκB and its target genes Bcl-2 and Bcl-xL. Our results suggest that the tumor- suppressive effect of the antioxidative fraction of white mulberry is likely due to apoptosis mediated by p53 and NFκB signaling. PMID:27936037

  11. Noscapine induced apoptosis via downregulation of survivin in human neuroblastoma cells having wild type or null p53.

    PubMed

    Li, Shiwang; He, Jing; Li, Shuai; Cao, Guoqing; Tang, Shaotao; Tong, Qiangsong; Joshi, Harish C

    2012-01-01

    Neuroblastoma is the most common extracranial solid tumor of childhood. It accounts for 15% of pediatric cancer deaths. Chemotherapy is the mainstay of treatment in children with advanced neuroblastoma. Noscapine, a nontoxic natural compound, can trigger apoptosis in many cancer types. We now show that p53 is dispensable for Noscapine-induced cell death in neuroblastoma cell lines, proapoptotic response to this promising chemopreventive agent is mediated by suppression of survivin protein expression. The Noscapine treatment increased levels of total and Ser(15)-phosphorylated p53 protein in SK-SY5Y cells, but the proapoptotic response to this agent was maintained even after knockdown of the p53 protein level. Exposure of SK-SY5Y and LA1-5S cells to Noscapine resulted in a marked decrease in protein and mRNA level of survivin as early as 12 hours after treatment. Ectopic expression of survivin conferred statistically significant protection against Noscapine-mediated cytoplasmic histone-associated apoptotic DNA fragmentation. Also, the Noscapine-induced apoptosis was modestly but statistically significantly augmented by RNA interference of survivin in both cell lines. Furthermore, Noscapine-induced apoptotic cell death was associated with activation of cas