Mutant p53 expression in fallopian tube epithelium drives cell migration.

PubMed

Quartuccio, Suzanne M; Karthikeyan, Subbulakshmi; Eddie, Sharon L; Lantvit, Daniel D; Ó hAinmhire, Eoghainín; Modi, Dimple A; Wei, Jian-Jun; Burdette, Joanna E

2015-10-01

Ovarian cancer is the fifth leading cause of cancer death among US women. Evidence supports the hypothesis that high-grade serous ovarian cancers (HGSC) may originate in the distal end of the fallopian tube. Although a heterogeneous disease, 96% of HGSC contain mutations in p53. In addition, the "p53 signature," or overexpression of p53 protein (usually associated with mutation), is a potential precursor lesion of fallopian tube derived HGSC suggesting an essential role for p53 mutation in early serous tumorigenesis. To further clarify p53-mutation dependent effects on cells, murine oviductal epithelial cells (MOE) were stably transfected with a construct encoding for the R273H DNA binding domain mutation in p53, the most common mutation in HGSC. Mutation in p53 was not sufficient to transform MOE cells but did significantly increase cell migration. A similar p53 mutation in murine ovarian surface epithelium (MOSE), another potential progenitor cell for serous cancer, was not sufficient to transform the cells nor change migration suggesting tissue specific effects of p53 mutation. Microarray data confirmed expression changes of pro-migratory genes in p53(R273H) MOE compared to parental cells, which could be reversed by suppressing Slug expression. Combining p53(R273H) with KRAS(G12V) activation caused transformation of MOE into high-grade sarcomatoid carcinoma when xenografted into nude mice. Elucidating the specific role of p53(R273H) in the fallopian tube will improve understanding of changes at the earliest stage of transformation. This information can help develop chemopreventative strategies to prevent the accumulation of additional mutations and reverse progression of the "p53 signature" thereby, improving survival rates. © 2015 UICC.

Relationships between p53 mutation, HPV status and outcome in oropharyngeal squamous cell carcinoma.

PubMed

Hong, Angela; Zhang, Xiaoying; Jones, Deanna; Veillard, Anne-Sophie; Zhang, Mei; Martin, Andrew; Lyons, J Guy; Lee, C Soon; Rose, Barbara

2016-02-01

This study aimed to examine the rate and type of p53 mutation in oropharyngeal cancer (OSCC). Relationships were sought between human papillomavirus (HPV) status and p53 mutation. The role of p53 mutation as a prognostic factor independent of HPV status and as a modifier of the effect of HPV on outcomes was also examined. The HPV status of 202 cases was determined by HPV DNA by RT-PCR and p16 immunohistochemistry. P53 mutation in exon 5-8 was determined by pyrosequencing. Findings were correlated with known clinicopathological factors and outcomes. 48% of the cases were HPV positive and they were significantly less likely to have a p53 mutation than HPV-negative OSCCs (25.8% vs 46.7%, p=0.0021). Mutation was most common in exon 5. Among patients with HPV-positive OSCC, there was no significant difference in p53 mutation by smoking status (22.2% for never smokers and 30.8% for current or ex-smokers). Patients with p53 mutant OSCC had significantly worse overall survival (p=0.01). There was no statistical evidence that p53 mutation modified the effect of HPV status on outcomes. In the multivariate analysis, positive HPV status remained the strongest predictor of outcomes. p53 mutation status was not a significant predictor of outcome after adjusting for age, gender, T stage, N stage and HPV status. In summary, HPV-positive OSCC are less likely to have mutant p53 than HPV-negative OSCC. Our study did not show any evidence that p53 mutation could modify the effect of HPV status on outcomes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Relationship between p53 dysfunction, CD38 expression, and IgV(H) mutation in chronic lymphocytic leukemia.

PubMed

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

2002-08-15

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

Transcriptional specificity in various p53-mutant cells.

PubMed

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

2013-03-01

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

CP-31398 inhibits the growth of p53-mutated liver cancer cells in vitro and in vivo.

PubMed

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

2016-01-01

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

The p16INK4alpha/p19ARF gene mutations are infrequent and are mutually exclusive to p53 mutations in Indian oral squamous cell carcinomas.

PubMed

Kannan, K; Munirajan, A K; Krishnamurthy, J; Bhuvarahamurthy, V; Mohanprasad, B K; Panishankar, K H; Tsuchida, N; Shanmugam, G

2000-03-01

Eighty-seven untreated primary oral squamous cell carcinomas (SCCs) associated with betel quid and tobacco chewing from Indian patients were analysed for the presence of mutations in the commonly shared exon 2 of p16INK4alpha/p19ARF genes. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing analysis were used to detect mutations. SSCP analysis indicated that only 9% (8/87) of the tumours had mutation in p16INK4alpha/p19ARF genes. Seventy-two tumours studied here were previously analysed for p53 mutations and 21% (15/72) of them were found to have mutations in p53 gene. Only one tumour was found to have mutation at both p53 and p16INK4alpha/p19ARF genes. Thus, the mutation rates observed were 21% for p53, 9% for p16INK4alpha/p19ARF, and 1% for both. Sequencing analysis revealed two types of mutations; i) G to C (GCAG to CCAG) transversion type mutation at intron 1-exon 2 splice junction and ii) another C to T transition type mutation resulting in CGA to TGA changing arginine to a termination codon at p16INK4alpha gene codon 80 and the same mutation will alter codon 94 of p19ARF gene from CCG to CTG (proline to leucine). These results suggest that p16INK4alpha/p19ARF mutations are less frequent than p53 mutations in Indian oral SCCs. The p53 and p16INK4alpha/p19ARF mutational events are independent and are mutually exclusive suggesting that mutational inactivation of either p53 or p16INK4alpha/p19ARF may alleviate the need for the inactivation of the other gene.

Adaptation of cancer cells from different entities to the MDM2 inhibitor nutlin-3 results in the emergence of p53-mutated multi-drug-resistant cancer cells

PubMed Central

Michaelis, M; Rothweiler, F; Barth, S; Cinatl, J; van Rikxoort, M; Löschmann, N; Voges, Y; Breitling, R; von Deimling, A; Rödel, F; Weber, K; Fehse, B; Mack, E; Stiewe, T; Doerr, H W; Speidel, D; Cinatl, J

2011-01-01

Six p53 wild-type cancer cell lines from infrequently p53-mutated entities (neuroblastoma, rhabdomyosarcoma, and melanoma) were continuously exposed to increasing concentrations of the murine double minute 2 inhibitor nutlin-3, resulting in the emergence of nutlin-3-resistant, p53-mutated sublines displaying a multi-drug resistance phenotype. Only 2 out of 28 sublines adapted to various cytotoxic drugs harboured p53 mutations. Nutlin-3-adapted UKF-NB-3 cells (UKF-NB-3rNutlin10 μM, harbouring a G245C mutation) were also radiation resistant. Analysis of UKF-NB-3 and UKF-NB-3rNutlin10 μM cells by RNA interference experiments and lentiviral transduction of wild-type p53 into p53-mutated UKF-NB-3rNutlin10 μM cells revealed that the loss of p53 function contributes to the multi-drug resistance of UKF-NB-3rNutlin10 μM cells. Bioinformatics PANTHER pathway analysis based on microarray measurements of mRNA abundance indicated a substantial overlap in the signalling pathways differentially regulated between UKF-NB-3rNutlin10 μM and UKF-NB-3 and between UKF-NB-3 and its cisplatin-, doxorubicin-, or vincristine-resistant sublines. Repeated nutlin-3 adaptation of neuroblastoma cells resulted in sublines harbouring various p53 mutations with high frequency. A p53 wild-type single cell-derived UKF-NB-3 clone was adapted to nutlin-3 in independent experiments. Eight out of ten resulting sublines were p53-mutated harbouring six different p53 mutations. This indicates that nutlin-3 induces de novo p53 mutations not initially present in the original cell population. Therefore, nutlin-3-treated cancer patients should be carefully monitored for the emergence of p53-mutated, multi-drug-resistant cells. PMID:22170099

p53 deficiency alters the yield and spectrum of radiation-induced lacZ mutants in the brain of transgenic mice

NASA Technical Reports Server (NTRS)

Chang, P. Y.; Kanazawa, N.; Lutze-Mann, L.; Winegar, R. A.

2001-01-01

Exposure to heavy particle radiation in the galacto-cosmic environment poses a significant risk in space exploration and the evaluation of radiation-induced genetic damage in tissues, especially in the central nervous system, is an important consideration in long-term manned space missions. We used a plasmid-based transgenic mouse model system, with the pUR288 lacZ transgene integrated in the genome of every cell of C57Bl/6(lacZ) mice, to evaluate the genetic damage induced by iron particle radiation. In order to examine the importance of genetic background on the radiation sensitivity of individuals, we cross-bred p53 wild-type lacZ transgenic mice with p53 nullizygous mice, producing lacZ transgenic mice that were either hemizygous or nullizygous for the p53 tumor suppressor gene. Animals were exposed to an acute dose of 1 Gy of iron particles and the lacZ mutation frequency (MF) in the brain was measured at time intervals from 1 to 16 weeks post-irradiation. Our results suggest that iron particles induced an increase in lacZ MF (2.4-fold increase in p53+/+ mice, 1.3-fold increase in p53+/- mice and 2.1-fold increase in p53-/- mice) and that this induction is both temporally regulated and p53 genotype dependent. Characterization of mutants based on their restriction patterns showed that the majority of the mutants arising spontaneously are derived from point mutations or small deletions in all three genotypes. Radiation induced alterations in the spectrum of deletion mutants and reorganization of the genome, as evidenced by the selection of mutants containing mouse genomic DNA. These observations are unique in that mutations in brain tissue after particle radiation exposure have never before been reported owing to technical limitations in most other mutation assays.

Adiposity is associated with p53 gene mutations in breast cancer.

PubMed

Ochs-Balcom, Heather M; Marian, Catalin; Nie, Jing; Brasky, Theodore M; Goerlitz, David S; Trevisan, Maurizio; Edge, Stephen B; Winston, Janet; Berry, Deborah L; Kallakury, Bhaskar V; Freudenheim, Jo L; Shields, Peter G

2015-10-01

Mutations in the p53 gene are among the most frequent genetic events in human cancer and may be triggered by environmental and occupational exposures. We examined the association of clinical and pathological characteristics of breast tumors and breast cancer risk factors according to the prevalence and type of p53 mutations. Using tumor blocks from incident cases from a case-control study in western New York, we screened for p53 mutations in exons 2-11 using the Affymetrix p53 Gene Chip array and analyzed case-case comparisons using logistic regression. The p53 mutation frequency among cases was 28.1 %; 95 % were point mutations (13 % of which were silent) and the remainder were single base pair deletions. Sixty seven percent of all point mutations were transitions; 24 % of them are G:C>A:T at CpG sites. Positive p53 mutation status was associated with poorer differentiation (OR, 95 % CI 2.29, 1.21-4.32), higher nuclear grade (OR, 95 % CI 1.99, 1.22-3.25), and increased Ki-67 status (OR, 95 % CI 1.81, 1.10-2.98). Cases with P53 mutations were more likely to have a combined ER-positive and PR-negative status (OR, 95 % CI 1.65, 1.01-2.71), and a combined ER-negative and PR-negative status (OR, 95 % CI 2.18, 1.47-3.23). Body mass index >30 kg/m(2), waist circumference >79 cm, and waist-to-hip ratio >0.86 were also associated with p53 status; obese breast cancer cases are more likely to have p53 mutations (OR, 95 % CI 1.78, 1.19-2.68). We confirmed that p53 mutations are associated with less favorable tumor characteristics and identified an association of p53 mutation status and adiposity.

Prognostic and predictive value of TP53 mutations in node-positive breast cancer patients treated with anthracycline- or anthracycline/taxane-based adjuvant therapy: results from the BIG 02-98 phase III trial

PubMed Central

2012-01-01

Abstract Introduction Pre-clinical data suggest p53-dependent anthracycline-induced apoptosis and p53-independent taxane activity. However, dedicated clinical research has not defined a predictive role for TP53 gene mutations. The aim of the current study was to retrospectively explore the prognosis and predictive values of TP53 somatic mutations in the BIG 02-98 randomized phase III trial in which women with node-positive breast cancer were treated with adjuvant doxorubicin-based chemotherapy with or without docetaxel. Methods The prognostic and predictive values of TP53 were analyzed in tumor samples by gene sequencing within exons 5 to 8. Patients were classified according to p53 protein status predicted from TP53 gene sequence, as wild-type (no TP53 variation or TP53 variations which are predicted not to modify p53 protein sequence) or mutant (p53 nonsynonymous mutations). Mutations were subcategorized according to missense or truncating mutations. Survival analyses were performed using the Kaplan-Meier method and log-rank test. Cox-regression analysis was used to identify independent predictors of outcome. Results TP53 gene status was determined for 18% (520 of 2887) of the women enrolled in BIG 02-98. TP53 gene variations were found in 17% (90 of 520). Nonsynonymous p53 mutations, found in 16.3% (85 of 520), were associated with older age, ductal morphology, higher grade and hormone-receptor negativity. Of the nonsynonymous mutations, 12.3% (64 of 520) were missense and 3.6% were truncating (19 of 520). Only truncating mutations showed significant independent prognostic value, with an increased recurrence risk compared to patients with non-modified p53 protein (hazard ratio = 3.21, 95% confidence interval = 1.740 to 5.935, P = 0.0002). p53 status had no significant predictive value for response to docetaxel. Conclusions p53 truncating mutations were uncommon but associated with poor prognosis. No significant predictive role for p53 status was detected. Trial registration ClinicalTrials.gov NCT00174655 PMID:22551440

Modeling the Etiology of p53-mutated Cancer Cells*

PubMed Central

Perez, Ricardo E.; Shen, Hong; Duan, Lei; Kim, Reuben H.; Kim, Terresa; Park, No-Hee; Maki, Carl G.

2016-01-01

p53 gene mutations are among the most common alterations in cancer. In most cases, missense mutations in one TP53 allele are followed by loss-of-heterozygosity (LOH), so tumors express only mutant p53. TP53 mutations and LOH have been linked, in many cases, with poor therapy response and worse outcome. Despite this, remarkably little is known about how TP53 point mutations are acquired, how LOH occurs, or the cells involved. Nutlin-3a occupies the p53-binding site in MDM2 and blocks p53-MDM2 interaction, resulting in the stabilization and activation of p53 and subsequent growth arrest or apoptosis. We leveraged the powerful growth inhibitory activity of Nutlin-3a to select p53-mutated cells and examined how TP53 mutations arise and how the remaining wild-type allele is lost or inactivated. Mismatch repair (MMR)-deficient colorectal cancer cells formed heterozygote (p53 wild-type/mutant) colonies when cultured in low doses of Nutlin-3a, whereas MMR-corrected counterparts did not. Placing these heterozygotes in higher Nutlin-3a doses selected clones in which the remaining wild-type TP53 was silenced. Our data suggest silencing occurred through a novel mechanism that does not involve DNA methylation, histone methylation, or histone deacetylation. These data indicate MMR deficiency in colorectal cancer can give rise to initiating TP53 mutations and that TP53 silencing occurs via a copy-neutral mechanism. Moreover, the data highlight the use of MDM2 antagonists as tools to study mechanisms of TP53 mutation acquisition and wild-type allele loss or silencing in cells with defined genetic backgrounds. PMID:27022024

Biomarker Detection Using NAPPA Tumor Antigen Arrays: EDRN Supplement — EDRN Public Portal

Cancer.gov

The overall goal of this project application for the EDRN set-aside funds is to focus our collaborative efforts to identify p53 mutation-specific antibody biomarkers in breast, prostate, and ovarian cancer. P53-specific gene mutations are frequent in multiple cancer types. Of the common solid tumors, p53 mutations have been identified in 50% of lung and ovarian cancers, 45% of colon cancers, 20% of breast cancers, and 10-30% of prostate cancers (The p53 Mutation Handbook, T. Soussi, http://p53/free/fr). The most common mutations vary from cancer to cancer, with 50 point mutations covering the 10 most common mutations for all major solid tumors

Clinical utility of anti-p53 auto-antibody: systematic review and focus on colorectal cancer.

PubMed

Suppiah, Aravind; Greenman, John

2013-08-07

Mutation of the p53 gene is a key event in the carcinogenesis of many different types of tumours. These can occur throughout the length of the p53 gene. Anti-p53 auto-antibodies are commonly produced in response to these p53 mutations. This review firstly describes the various mechanisms of p53 dysfunction and their association with subsequent carcinogenesis. Following this, the mechanisms of induction of anti-p53 auto-antibody production are shown, with various hypotheses for the discrepancies between the presence of p53 mutation and the presence/absence of anti-p53 auto-antibodies. A systematic review was performed with a descriptive summary of key findings of each anti-p53 auto-antibody study in all cancers published in the last 30 years. Using this, the cumulative frequency of anti-p53 auto-antibody in each cancer type is calculated and then compared with the incidence of p53 mutation in each cancer to provide the largest sample calculation and correlation between mutation and anti-p53 auto-antibody published to date. Finally, the review focuses on the data of anti-p53 auto-antibody in colorectal cancer studies, and discusses future strategies including the potentially promising role using anti-p53 auto-antibody presence in screening and surveillance.

Insights into wild-type and mutant p53 functions provided by genetically engineered mice.

PubMed

Donehower, Lawrence A

2014-06-01

Recent whole-exome sequencing studies of numerous human cancers have now conclusively shown that the TP53 tumor-suppressor gene is the most frequently mutated gene in human cancers. Despite extensive studies of the TP53 gene and its encoded protein (p53), our understanding of how TP53 mutations contribute to cancer initiation and progression remain incomplete. Genetically engineered mice with germline or inducible Trp53 somatic mutations have provided important insights into the mechanisms by which different types of p53 mutation influence cancer development. Trp53 germline mutations that alter specific p53 structural domains or posttranslation modification sites have benefitted our understanding of wild-type p53 functions in a whole organism context. Moreover, genetic approaches to reestablish functional wild-type p53 to p53-deficient tissues and tumors have increased our understanding of the therapeutic potential of restoring functional p53 signaling to cancers. This review outlines many of the key insights provided by the various categories of Trp53 mutant mice that have been generated by multiple genetic engineering approaches. © 2014 WILEY PERIODICALS, INC.

p53 mutation and expression in lymphoma.

PubMed Central

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

1995-01-01

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

Genomic alterations in spontaneous and carcinogen-induced murine melanoma cell lines.

PubMed

Melnikova, Vladislava O; Bolshakov, Svetlana V; Walker, Christopher; Ananthaswamy, Honnavara N

2004-03-25

We have conducted an analysis of genetic alterations in spontaneous murine melanoma cell line B16F0 and its two metastatic clones, B16F1 and B16F10 and the carcinogen-induced murine melanoma cell lines CM519, CM3205, and K1735. We found that unlike human melanomas, the murine melanoma cell lines did not have activating mutations in the Braf oncogene at exon 11 or 15. However, there were distinct patterns of alterations in the ras, Ink4a/Arf, and p53 genes in the two melanoma groups. In the spontaneous B16 melanoma cell lines, expression of p16Ink4a and p19Arf tumor suppressor proteins was lost as a consequence of a large deletion spanning Ink4a/Arf exons 1alpha, 1beta, and 2. In contrast, the carcinogen-induced melanoma cell lines expressed p16Ink4a but had inactivating mutations in either p19Arf (K1735) or p53 (CM519 and CM3205). Inactivation of p19Arf or p53 in carcinogen-induced melanomas was accompanied by constitutive activation of mitogen-activated protein kinases (MAPKs) and/or mutation-associated activation of N-ras. These results indicate that genetic alterations in p16Ink4a/p19Arf, p53 and ras-MAPK pathways can cooperate in the development of murine melanoma.

Mutations in TP53 are a prognostic factor in colorectal hepatic metastases undergoing surgical resection.

PubMed

Molleví, David G; Serrano, Teresa; Ginestà, Mireia M; Valls, Joan; Torras, Jaume; Navarro, Matilde; Ramos, Emilio; Germà, Josep R; Jaurrieta, Eduardo; Moreno, Víctor; Figueras, Joan; Capellà, Gabriel; Villanueva, Alberto

2007-06-01

The aim of this study was to analyze the prognostic value of TP53 mutations in a consecutive series of patients with hepatic metastases (HMs) from colorectal cancer undergoing surgical resection. Ninety-one patients with liver metastases from colorectal carcinoma were included. Mutational analysis of TP53, exons 4-10, was performed by single-strand conformation polymorphism and sequencing. P53 and P21 protein immunostaining was assessed. Multivariate Cox models were adjusted for gender, number of metastasis, resection margin, presence of TP53 mutations and chemotherapy treatment. Forty-six of 91 (50.05%) metastases showed mutations in TP53, observed mainly in exons 5-8, although 14.3% (n = 13) were located in exons 9 and 10. Forty percent (n = 22) were protein-truncating mutations. TP53 status associated with multiple (> or =3) metastases (65.6%, P = 0.033), advanced primary tumor Dukes' stage (P = 0.011) and younger age (<57 years old, P = 0.03). Presence of mutation associated with poor prognosis in univariate (P = 0.017) and multivariate Cox model [hazard ratio (HR) = 1.80, 95% confidence interval (CI) = 1.07-3.06, P = 0.028]. Prognostic value was maintained in patients undergoing radical resection (R0 series, n = 79, P = 0.014). Mutation associated with a worse outcome in chemotherapy-treated patients (HR = 2.54, 95% CI = 1.12-5.75, P = 0.026). The combination of > or =3 metastases and TP53 mutation identified a subset of patients with very poor prognosis (P = 0.009). P53 and P21 protein immunostaining did not show correlation with survival. TP53 mutational status seems to be an important prognostic factor in patients undergoing surgical resection of colorectal cancer HMs.

Enhanced breast cancer progression by mutant p53 is inhibited by the circular RNA circ-Ccnb1.

PubMed

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

2018-05-23

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

Germ-line mutations of the p53 tumor suppressor gene in patients with high risk for cancer inactivate the p53 protein.

PubMed Central

Frebourg, T; Kassel, J; Lam, K T; Gryka, M A; Barbier, N; Andersen, T I; Børresen, A L; Friend, S H

1992-01-01

Germ-line mutations in the p53 tumor suppressor gene have been observed in patients with Li-Fraumeni syndrome, brain tumors, second malignancies, and breast cancers. It is unclear whether all of these mutations have inactivated p53 and thereby provide an increased risk for cancer. Therefore, it is necessary to establish the biological significance of these germ-line mutations by the functional and structural analysis of the resulting mutant p53 proteins. We analyzed the ability of seven germ-line mutant proteins observed in patients with Li-Fraumeni syndrome, second primary neoplasms, or familial breast cancer to block the growth of malignant cells and compared the structural properties of the mutant proteins to that of the wild-type protein. Six of seven missense mutations disrupted the growth inhibitory properties and structure of the wild-type protein. One germ-line mutation retained the features of the wild-type p53. Genetic analysis of the breast cancer family in which this mutation was observed indicated that this germ-line mutation was not associated with the development of cancer. These results demonstrate that germ-line p53 mutations observed in patients with Li-Fraumeni syndrome and with second malignancies have inactivated the p53 tumor suppressor gene. The inability of the germ-line p53 mutants to block the growth of malignant cells can explain why patients with these germ-line mutations have an increased risk for cancer. The observation of a functionally silent germ-line mutation indicates that, before associating a germ-line tumor suppressor gene mutation with cancer risk, it is prudent to consider its functional significance. Images PMID:1631137

Germ-line mutations of the p53 tumor suppressor gene in patients with high risk for cancer inactivate the p53 protein.

PubMed

Frebourg, T; Kassel, J; Lam, K T; Gryka, M A; Barbier, N; Andersen, T I; Børresen, A L; Friend, S H

1992-07-15

Germ-line mutations in the p53 tumor suppressor gene have been observed in patients with Li-Fraumeni syndrome, brain tumors, second malignancies, and breast cancers. It is unclear whether all of these mutations have inactivated p53 and thereby provide an increased risk for cancer. Therefore, it is necessary to establish the biological significance of these germ-line mutations by the functional and structural analysis of the resulting mutant p53 proteins. We analyzed the ability of seven germ-line mutant proteins observed in patients with Li-Fraumeni syndrome, second primary neoplasms, or familial breast cancer to block the growth of malignant cells and compared the structural properties of the mutant proteins to that of the wild-type protein. Six of seven missense mutations disrupted the growth inhibitory properties and structure of the wild-type protein. One germ-line mutation retained the features of the wild-type p53. Genetic analysis of the breast cancer family in which this mutation was observed indicated that this germ-line mutation was not associated with the development of cancer. These results demonstrate that germ-line p53 mutations observed in patients with Li-Fraumeni syndrome and with second malignancies have inactivated the p53 tumor suppressor gene. The inability of the germ-line p53 mutants to block the growth of malignant cells can explain why patients with these germ-line mutations have an increased risk for cancer. The observation of a functionally silent germ-line mutation indicates that, before associating a germ-line tumor suppressor gene mutation with cancer risk, it is prudent to consider its functional significance.

Clinical utility of anti-p53 auto-antibody: Systematic review and focus on colorectal cancer

PubMed Central

Suppiah, Aravind; Greenman, John

2013-01-01

Mutation of the p53 gene is a key event in the carcinogenesis of many different types of tumours. These can occur throughout the length of the p53 gene. Anti-p53 auto-antibodies are commonly produced in response to these p53 mutations. This review firstly describes the various mechanisms of p53 dysfunction and their association with subsequent carcinogenesis. Following this, the mechanisms of induction of anti-p53 auto-antibody production are shown, with various hypotheses for the discrepancies between the presence of p53 mutation and the presence/absence of anti-p53 auto-antibodies. A systematic review was performed with a descriptive summary of key findings of each anti-p53 auto-antibody study in all cancers published in the last 30 years. Using this, the cumulative frequency of anti-p53 auto-antibody in each cancer type is calculated and then compared with the incidence of p53 mutation in each cancer to provide the largest sample calculation and correlation between mutation and anti-p53 auto-antibody published to date. Finally, the review focuses on the data of anti-p53 auto-antibody in colorectal cancer studies, and discusses future strategies including the potentially promising role using anti-p53 auto-antibody presence in screening and surveillance. PMID:23922463

Analysis of full coding sequence of the TP53 gene in invasive vulvar cancers: Implications for therapy.

PubMed

Kashofer, Karl; Regauer, Sigrid

2017-08-01

This study evaluates the frequency and type of TP53 gene mutations and HPV status in 72 consecutively diagnosed primary invasive vulvar squamous cell carcinomas (SCC) during the past 5years. DNA of formalin-fixed and paraffin embedded tumour tissue was analysed for 32 HPV subtypes and the full coding sequence of the TP53 gene, and correlated with results of p53 immunohistochemistry. 13/72 (18%) cancers were HPV-induced squamous cell carcinomas, of which 1/13 (8%) carcinoma harboured a somatic TP53 mutation. Among the 59/72 (82%) HPV-negative cancers, 59/72 (82%) SCC were HPV-negative with wild-type gene in 14/59 (24%) SCC and somatic TP53 mutations in 45/59 (76%) SCC. 28/45 (62%) SCC carried one (n=20) or two (n=8) missense mutations. 11/45 (24%) carcinomas showed a single disruptive mutation (3× frame shift, 7× stop codon, 1× deletion), 3/45 SCC a splice site mutation. 3/45 (7%) carcinomas had 2 or 3 different mutations. 18 different "hot spot" mutations were observed in 22/45 cancers (49%; 5× R273, 3× R282; 2× each Y220, R278, R248). Immunohistochemical p53 over expression was identified in most SCC with missense mutations, but not in SCC with disruptive TP53 mutations or TP53 wild-type. 14/45 (31%) patients with TP53 mutated SCC died of disease within 12months (range 2-24months) versus 0/13 patients with HPV-induced carcinomas and 0/14 patients with HPV-negative, TP53 wild-type carcinomas. 80% of primary invasive vulvar SCC were HPV-negative carcinomas with a high frequency of disruptive mutations and "hot spot" TP53 gene mutations, which have been linked to chemo- and radioresistance. The death rate of patients with p53 mutated vulvar cancers was 31%. Immunohistochemical p53 over expression could not reliably identify SCC with TP53 gene mutation. Pharmacological therapies targeting mutant p53 will be promising strategies for personalized therapy in patients with TP53 mutated vulvar cancers. Copyright © 2017. Published by Elsevier Inc.

Farewell to oligoastrocytoma: in situ molecular genetics favor classification as either oligodendroglioma or astrocytoma.

PubMed

Sahm, Felix; Reuss, David; Koelsche, Christian; Capper, David; Schittenhelm, Jens; Heim, Stephanie; Jones, David T W; Pfister, Stefan M; Herold-Mende, Christel; Wick, Wolfgang; Mueller, Wolf; Hartmann, Christian; Paulus, Werner; von Deimling, Andreas

2014-10-01

Astrocytoma and oligodendroglioma are histologically and genetically well-defined entities. The majority of astrocytomas harbor concurrent TP53 and ATRX mutations, while most oligodendrogliomas carry the 1p/19q co-deletion. Both entities share high frequencies of IDH mutations. In contrast, oligoastrocytomas (OA) appear less clearly defined and, therefore, there is an ongoing debate whether these tumors indeed constitute an entity or whether they represent a mixed bag containing both astrocytomas and oligodendrogliomas. We investigated 43 OA diagnosed in different institutions employing histology, immunohistochemistry and in situ hybridization addressing surrogates for the molecular genetic markers IDH1R132H, TP53, ATRX and 1p/19q loss. In all but one OA the combination of nuclear p53 accumulation and ATRX loss was mutually exclusive with 1p/19q co-deletion. In 31/43 OA, only alterations typical for oligodendroglioma were observed, while in 11/43 OA, only indicators for mutations typical for astrocytomas were detected. A single case exhibited a distinct pattern, nuclear expression of p53, ATRX loss, IDH1 mutation and partial 1p/19q loss. However, this was the only patient undergoing radiotherapy prior to surgery, possibly contributing to the acquisition of this uncommon combination. In OA with oligodendroglioma typical alterations, the portions corresponding to astrocytic part were determined as reactive, while in OA with astrocytoma typical alterations the portions corresponding to oligodendroglial differentiation were neoplastic. These data provide strong evidence against the existence of an independent OA entity.

TP53 mutations, expression and interaction networks in human cancers

PubMed Central

Wang, Xiaosheng; Sun, Qingrong

2017-01-01

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

TP53 mutations, expression and interaction networks in human cancers.

PubMed

Wang, Xiaosheng; Sun, Qingrong

2017-01-03

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

p53 sequence analysis predicts treatment response and outcome of patients with esophageal carcinoma.

PubMed

Ribeiro, U; Finkelstein, S D; Safatle-Ribeiro, A V; Landreneau, R J; Clarke, M R; Bakker, A; Swalsky, P A; Gooding, W E; Posner, M C

1998-07-01

The ability to predict biologic behavior and treatment responsiveness would be a valuable asset in the multimodality approach to esophageal carcinoma. The authors examined whether alterations of the p53 gene correlate with clinicopathologic parameters, response to preoperative chemotherapy/radiotherapy, and outcome in patients with esophageal carcinoma. METHODS. Histopathologic/genetic analysis of p53 was performed on formalin fixed, paraffin embedded tissues. Tissue sections were stained immunohistochemically for p53 protein followed by topographic genotyping comprised of polymerase chain reaction amplification and direct sequencing of p53 exons 5-8. All patients received induction chemotherapy (5-fluorouracil, cisplatin, and alpha-interferon) and concurrent external beam radiotherapy (4500 centigrays) followed by resection. p53 analysis performed on 42 tumors from patients with potentially resectable esophageal carcinoma revealed 25 of the 42 tumors (59.5%) to be p53 immunopositive; however, only 17 of the 42 tumors (40.5%) were proven to contain p53 point mutational damage in exons 8 (n=5), 5 (n=5), 7 (n=4), and 6 (n=3). Eight cases were weakly immunopositive and had no genotype mutation suggesting hyperexpression of normal wild-type p53. Genotyping also identified two immunonegative cases with deletion-type mutations (exons 5 and 6). Tissue samples collected before and after chemotherapy/radiotherapy exhibited fidelity in p53 mutational genotype in all cases. The presence of a p53 point mutation positively correlated with pTNM stage (P=0.003) and residual disease in the resected specimen (P=0.01). Moreover, survival of patients with p53 mutations was significantly lower than that of patients without mutations (overall survival of 21.6 months vs. 40 months; P=0.0038; and disease free survival of 14.1 months vs. 38 months; P=0.0004). Histopathologic/genetic analysis is a better determinant of p53 mutational damage than immunohistochemistry alone and can be used as a prognostic marker for esophageal carcinoma. p53 genotyping may define a subset of patients who respond to chemotherapy/radiotherapy and may predict who potentially benefits from multimodality therapy.

p53 expression and mutation analysis of odontogenic cysts with and without dysplasia.

PubMed

Cox, Darren P

2012-01-01

Overexpression of p53 protein is well described in odontogenic cystic lesions (OCLs), including those with epithelial dysplasia; however, most p53 antibodies stain both wild-type and mutated p53 protein and may not reflect genotype. Direct sequencing of the p53 gene has not identified mutations in OCLs with dysplasia. The purpose of this study was to determine the molecular basis of p53 expression in several types of OCLs with and without dysplasia. The study material comprised 13 OCLs: odontogenic keratocyst (n = 5), orthokeratinized odontogenic cyst (n = 5), dentigerous cyst (n = 2), lateral periodontal cyst (n = 1), and unspecified developmental odontogenic cyst (UDOC) (n = 1). Five of these had features of mild or moderate epithelial dysplasia. One intraosseous squamous cell carcinoma (SCC) that was believed to have arisen from an antecedent dysplastic orthokeratinized OC was also included. Immunohistochemistry was performed using the DO7 monoclonal antibody that recognizes wild-type and mutated p53. DNA was extracted from microdissected tissue for all samples and exons 4 to 8 of the p53 gene direct sequenced. In 4 of 5 OCLs with dysplasia there was strong nuclear staining of basal and suprabasal cells. In all cases without dysplasia, nuclear expression in basal cells was either negative or weak and was absent in suprabasal cell nuclei. A mutation in exon 6 of the p53 gene (E224D) was identified in both the dysplastic orthokeratinized OC and the subsequent intraosseous SCC. OCLs with features of dysplasia show increased expression of p53 protein that does not reflect p53 mutational status. One dysplastic OC shared the same p53 mutation with a subsequent intraosseous SCC, indicating that p53 mutation may be associated with malignant transformation in this case. Copyright © 2012 Elsevier Inc. All rights reserved.

p53 mutations promote proteasomal activity.

PubMed

Oren, Moshe; Kotler, Eran

2016-07-27

p53 mutations occur very frequently in human cancer. Besides abrogating the tumour suppressive functions of wild-type p53, many of those mutations also acquire oncogenic gain-of-function activities. Augmentation of proteasome activity is now reported as a common gain-of-function mechanism shared by different p53 mutants, which promotes cancer resistance to proteasome inhibitors.

p53 in pure epithelioid PEComa: an immunohistochemistry study and gene mutation analysis.

PubMed

Bing, Zhanyong; Yao, Yuan; Pasha, Theresa; Tomaszewski, John E; Zhang, Paul J

2012-04-01

Pure epithelioid PEComa (PEP; so-called epithelioid angiomyolipoma) is rare and is more often associated with aggressive behaviors. The pathogenesis of PEP has been poorly understood. The authors studied p53 expression and gene mutation in PEPs by immunohistochemistry, single-strand conformation polymorphism, and direct sequencing in paraffin material from 8 PEPs. A group of classic angiomyolipomas (AMLs) were also analyzed for comparison. Five PEPs were from kidneys and 1 each from the heart, the liver, and the uterus. PEPs showed much stronger p53 nuclear staining (Allred score 6.4 ± 2.5) than the classic AML (2.3 ± 2.9) (P < .01). There was no p53 single-strand conformation polymorphism identified in either the PEPs or the 8 classic AMLs. p53 mutation analyses by direct sequencing of exons 5 to 9 showed 4 mutations in 3 of 8 PEPs but none in any of the 8 classic AMLs. The mutations included 2 missense mutations in a hepatic PEComa and 2 silent mutations in 2 renal PEPs. Both the missense mutations in the hepatic PEComa involved the exon 5, one involving codon 165, with change from CAG to CAC (coding amino acid changed from glutamine to histidine), and the other involving codon 182, with change from TGC to TAC (coding amino acid changed from cysteine to tyrosine). The finding of stronger p53 expression and mutations in epithelioid angiomyolipomas might have contributed to their less predictable behavior. However, the abnormal p53 expression cannot be entirely explained by p53 mutations in the exons examined in the PEPs.

Role of TP53 mutations in triple negative and HER2-positive breast cancer treated with neoadjuvant anthracycline/taxane-based chemotherapy.

PubMed

Darb-Esfahani, Silvia; Denkert, Carsten; Stenzinger, Albrecht; Salat, Christoph; Sinn, Bruno; Schem, Christian; Endris, Volker; Klare, Peter; Schmitt, Wolfgang; Blohmer, Jens-Uwe; Weichert, Wilko; Möbs, Markus; Tesch, Hans; Kümmel, Sherko; Sinn, Peter; Jackisch, Christian; Dietel, Manfred; Reimer, Toralf; Loi, Sherene; Untch, Michael; von Minckwitz, Gunter; Nekljudova, Valentina; Loibl, Sibylle

2016-10-18

TP53 mutations are frequent in breast cancer, however their clinical relevance in terms of response to chemotherapy is controversial. 450 pre-therapeutic, formalin-fixed, paraffin-embedded core biopsies from the phase II neoadjuvant GeparSixto trial that included HER2-positive and triple negative breast cancer (TNBC) were subjected to Sanger sequencing of exons 5-8 of the TP53 gene. TP53 status was correlated to response to neoadjuvant anthracycline/taxane-based chemotherapy with or without carboplatin and trastuzumab/lapatinib in HER2-positive and bevacizumab in TNBC. p53 protein expression was evaluated by immunohistochemistry in the TNBC subgroup. Of 450 breast cancer samples 297 (66.0%) were TP53 mutant. Mutations were significantly more frequent in TNBC (74.8%) compared to HER2-positive cancers (55.4%, P < 0.0001). Neither mutations nor different mutation types and effects were associated with pCR neither in the whole study group nor in molecular subtypes (P > 0.05 each). Missense mutations tended to be associated with a better survival compared to all other types of mutations in TNBC (P = 0.093) and in HER2-positive cancers (P = 0.071). In TNBC, missense mutations were also linked to higher numbers of tumor-infiltrating lymphocytes (TILs, P = 0.028). p53 protein overexpression was also linked with imporved survival (P = 0.019). Our study confirms high TP53 mutation rates in TNBC and HER2-positive breast cancer. Mutations did not predict the response to an intense neoadjuvant chemotherapy in these two molecular breast cancer subtypes.

Intraperitoneal dedifferentiated liposarcoma: A case report

PubMed Central

Karaman, Ali; Kabalar, Mehmet Eşref; Özcan, Önder; Koca, Timur; Binici, Doğan Nasır

2008-01-01

Dedifferentiated liposarcoma is a variant of liposarcoma with a more aggressive course. Mutations of the p53 gene have been found in different types of soft tissue sarcoma. It is generally accepted that p53 mutations in human malignant tumors are often related to a poor prognosis. In our case, analysis of p53 gene mutation in tumor samples was performed. p53 gene mutation was observed in dedifferentiated tumor tissue samples but not in well-differentiated tumor tissue samples. It has been reported that p53 gene mutation occurs most commonly in the retroperitoneum and rarely in other anatomic locations. Herein we report a case of dedifferentiated liposarcoma located at intraperitoneum. PMID:18855997

Ineffectiveness of the presence of H-ras/p53 combination of mutations in squamous cell carcinoma cells to induce a conversion of a nontumorigenic to a tumorigenic phenotype.

PubMed

Lee, H; Li, D; Prior, T; Casto, B C; Weghorst, C M; Shuler, C F; Milo, G E

1997-10-01

Human tumor cells have properties in vitro or in surrogate hosts that are distinct from those of normal cells, such as immortality, anchorage independence, and tumor formation in nude mice. However, different cells from individual tumors may exhibit some, but not all of these features. In previous years, human tumor cell lines derived from different tumor and tissue types have been studied to determine those molecular changes that are associated with the in vitro properties listed above and with tumorigenicity in nude mice. In the present study, seven cell lines derived from human tumors were characterized for p53 and ras mutations that may occur in SCC tumor phenotypes and for tumor formation in nude mice. This investigation was designed to examine whether co-occurrence of mutated ras and p53 lead to a malignant stage in the progression process. None of the seven cell lines contained mutations in the recognized "hot spots" of the p53 tumor suppressor gene, but four had a nonsense/splice mutation in codon 126 and a mutation in codon 12 of the H-ras gene. The remaining three cell lines had p53 mutations in intron 5, in codon 193, and a missense mutation in codon 126, respectively. Four of seven cell lines were nontumorigenic; two of these cell lines contained a nonsense p53-126 mutation and mutated ras; one had a missense mutation at codon 126 but no mutated ras; the the fourth had only a p53 mutation at codon 193. Two of the nontumorigenic cell lines were converted to tumorigenicity after treatment with methyl methanesulfonate or N-methyl-N'-nitro-N-nitrosoguanidine with no apparent additional mutations in either gene. Our analysis revealed that there was a high frequency of genetic diversity and mutations in both p53 and H-ras. There was also a lack of a causal relationship in the presence of mutations in p53 and the cells' ability to exhibit a malignant potential in nude mice.

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

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

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

2011-01-01

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

Structural studies of p53 inactivation by DNA-contact mutations and its rescue by suppressor mutations via alternative protein–DNA interactions

PubMed Central

Eldar, Amir; Rozenberg, Haim; Diskin-Posner, Yael; Rohs, Remo; Shakked, Zippora

2013-01-01

A p53 hot-spot mutation found frequently in human cancer is the replacement of R273 by histidine or cysteine residues resulting in p53 loss of function as a tumor suppressor. These mutants can be reactivated by the incorporation of second-site suppressor mutations. Here, we present high-resolution crystal structures of the p53 core domains of the cancer-related proteins, the rescued proteins and their complexes with DNA. The structures show that inactivation of p53 results from the incapacity of the mutated residues to form stabilizing interactions with the DNA backbone, and that reactivation is achieved through alternative interactions formed by the suppressor mutations. Detailed structural and computational analysis demonstrates that the rescued p53 complexes are not fully restored in terms of DNA structure and its interface with p53. Contrary to our previously studied wild-type (wt) p53-DNA complexes showing non-canonical Hoogsteen A/T base pairs of the DNA helix that lead to local minor-groove narrowing and enhanced electrostatic interactions with p53, the current structures display Watson–Crick base pairs associated with direct or water-mediated hydrogen bonds with p53 at the minor groove. These findings highlight the pivotal role played by R273 residues in supporting the unique geometry of the DNA target and its sequence-specific complex with p53. PMID:23863845

Malignancy Risk Models for Oral Lesions

PubMed Central

Zarate, Ana M.; Brezzo, María M.; Secchi, Dante G.; Barra, José L.

2013-01-01

Objectives: The aim of this work was to assess risk habits, clinical and cellular phenotypes and TP53 DNA changes in oral mucosa samples from patients with Oral Potentially Malignant Disorders (OPMD), in order to create models that enable genotypic and phenotypic patterns to be obtained that determine the risk of lesions becoming malignant. Study Design: Clinical phenotypes, family history of cancer and risk habits were collected in clinical histories. TP53 gene mutation and morphometric-morphological features were studied, and multivariate models were applied. Three groups were estabished: a) oral cancer (OC) group (n=10), b) OPMD group (n=10), and c) control group (n=8). Results: An average of 50% of patients with malignancy were found to have smoking and drinking habits. A high percentage of TP53 mutations were observed in OC (30%) and OPMD (average 20%) lesions (p=0.000). The majority of these mutations were GC ? TA transversion mutations (60%). However, patients with OC presented mutations in all the exons and introns studied. Highest diagnostic accuracy (p=0.0001) was observed when incorporating alcohol and tobacco habits variables with TP53 mutations. Conclusions: Our results prove to be statistically reliable, with parameter estimates that are nearly unbiased even for small sample sizes. Models 2 and 3 were the most accurate for assessing the risk of an OPMD becoming cancerous. However, in a public health context, model 3 is the most recommended because the characteristics considered are easier and less costly to evaluate. Key words:TP53, oral potentially malignant disorders, risk factors, genotype, phenotype. PMID:23722122

Role of TP53 mutations in triple negative and HER2-positive breast cancer treated with neoadjuvant anthracycline/taxane-based chemotherapy

PubMed Central

Darb-Esfahani, Silvia; Denkert, Carsten; Stenzinger, Albrecht; Salat, Christoph; Sinn, Bruno; Schem, Christian; Endris, Volker; Klare, Peter; Schmitt, Wolfgang; Blohmer, Jens-Uwe; Weichert, Wilko; Möbs, Markus; Tesch, Hans; Kümmel, Sherko; Sinn, Peter; Jackisch, Christian; Dietel, Manfred; Reimer, Toralf; Loi, Sherene; Untch, Michael; von Minckwitz, Gunter; Nekljudova, Valentina; Loibl, Sibylle

2016-01-01

Background TP53 mutations are frequent in breast cancer, however their clinical relevance in terms of response to chemotherapy is controversial. Methods 450 pre-therapeutic, formalin-fixed, paraffin-embedded core biopsies from the phase II neoadjuvant GeparSixto trial that included HER2-positive and triple negative breast cancer (TNBC) were subjected to Sanger sequencing of exons 5-8 of the TP53 gene. TP53 status was correlated to response to neoadjuvant anthracycline/taxane-based chemotherapy with or without carboplatin and trastuzumab/lapatinib in HER2-positive and bevacizumab in TNBC. p53 protein expression was evaluated by immunohistochemistry in the TNBC subgroup. Results Of 450 breast cancer samples 297 (66.0%) were TP53 mutant. Mutations were significantly more frequent in TNBC (74.8%) compared to HER2-positive cancers (55.4%, P < 0.0001). Neither mutations nor different mutation types and effects were associated with pCR neither in the whole study group nor in molecular subtypes (P > 0.05 each). Missense mutations tended to be associated with a better survival compared to all other types of mutations in TNBC (P = 0.093) and in HER2-positive cancers (P = 0.071). In TNBC, missense mutations were also linked to higher numbers of tumor-infiltrating lymphocytes (TILs, P = 0.028). p53 protein overexpression was also linked with imporved survival (P = 0.019). Conclusions Our study confirms high TP53 mutation rates in TNBC and HER2-positive breast cancer. Mutations did not predict the response to an intense neoadjuvant chemotherapy in these two molecular breast cancer subtypes. PMID:27611952

Classification of TP53 Mutations and HPV Predict Survival in Advanced Larynx Cancer

PubMed Central

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

2016-01-01

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

Molecular Classification of Low-Grade Diffuse Gliomas

PubMed Central

Kim, Young-Ho; Nobusawa, Sumihito; Mittelbronn, Michel; Paulus, Werner; Brokinkel, Benjamin; Keyvani, Kathy; Sure, Ulrich; Wrede, Karsten; Nakazato, Yoichi; Tanaka, Yuko; Vital, Anne; Mariani, Luigi; Stawski, Robert; Watanabe, Takuya; De Girolami, Umberto; Kleihues, Paul; Ohgaki, Hiroko

2010-01-01

The current World Health Organization classification recognizes three histological types of grade II low-grade diffuse glioma (diffuse astrocytoma, oligoastrocytoma, and oligodendroglioma). However, the diagnostic criteria, in particular for oligoastrocytoma, are highly subjective. The aim of our study was to establish genetic profiles for diffuse gliomas and to estimate their predictive impact. In this study, we screened 360 World Health Organization grade II gliomas for mutations in the IDH1, IDH2, and TP53 genes and for 1p/19q loss and correlated these with clinical outcome. Most tumors (86%) were characterized genetically by TP53 mutation plus IDH1/2 mutation (32%), 1p/19q loss plus IDH1/2 mutation (37%), or IDH1/2 mutation only (17%). TP53 mutations only or 1p/19q loss only was rare (2 and 3%, respectively). The median survival of patients with TP53 mutation ± IDH1/2 mutation was significantly shorter than that of patients with 1p/19q loss ± IDH1/2 mutation (51.8 months vs. 58.7 months, respectively; P = 0.0037). Multivariate analysis with adjustment for age and treatment confirmed these results (P = 0.0087) and also revealed that TP53 mutation is a significant prognostic marker for shorter survival (P = 0.0005) and 1p/19q loss for longer survival (P = 0.0002), while IDH1/2 mutations are not prognostic (P = 0.8737). The molecular classification on the basis of IDH1/2 mutation, TP53 mutation, and 1p/19q loss has power similar to histological classification and avoids the ambiguity inherent to the diagnosis of oligoastrocytoma. PMID:21075857

Exclusive Association of p53 Mutation with Super-High Methylation of Tumor Suppressor Genes in the p53 Pathway in a Unique Gastric Cancer Phenotype.

PubMed

Waraya, Mina; Yamashita, Keishi; Ema, Akira; Katada, Natsuya; Kikuchi, Shiro; Watanabe, Masahiko

2015-01-01

A comprehensive search for DNA methylated genes identified candidate tumor suppressor genes that have been proven to be involved in the apoptotic process of the p53 pathway. In this study, we investigated p53 mutation in relation to such epigenetic alteration in primary gastric cancer. The methylation profiles of the 3 genes: PGP9.5, NMDAR2B, and CCNA1, which are involved in the p53 tumor suppressor pathway in combination with p53 mutation were examined in 163 primary gastric cancers. The effect of epigenetic reversion in combination with chemotherapeutic drugs on apoptosis was also assessed according to the tumor p53 mutation status. p53 gene mutations were found in 44 primary gastric tumors (27%), and super-high methylation of any of the 3 genes was only found in cases with wild type p53. Higher p53 pathway aberration was found in cases with male gender (p = 0.003), intestinal type (p = 0.005), and non-infiltrating type (p = 0.001). The p53 pathway aberration group exhibited less recurrence in lymph nodes, distant organs, and peritoneum than the p53 non-aberration group. In the NUGC4 gastric cancer cell line (p53 wild type), epigenetic treatment augmented apoptosis by chemotherapeutic drugs, partially through p53 transcription activity. On the other hand, in the KATO III cancer cell line (p53 mutant), epigenetic treatment alone induced robust apoptosis, with no trans-activation of p53. In gastric cancer, p53 relevant and non-relevant pathways exist, and tumors with either pathway type exhibited unique clinical features. Epigenetic treatments can induce apoptosis partially through p53 activation, however their apoptotic effects may be explained largely by mechanism other than through p53 pathways.

Abnormal expression and mutation of p53 in cervical cancer--a study at protein, RNA and DNA levels.

PubMed

Ngan, H Y; Tsao, S W; Liu, S S; Stanley, M

1997-02-01

The objectives of this study are to document the status of p53 expression and mutation in cervical cancer at protein, RNA and DNA levels and to relate this to the presence of HPV. Biopsy specimens from one hundred and three squamous cell carcinoma of the cervix and histologically normal ectocervix were analysed. Fresh tissues were extracted for protein, RNA and DNA and flash frozen tissue cryostat sectioned for immunohistochemical staining. HPV DNA status was determined by PCR using L1 consensus primers and typed for HPV 16 and 18 with E6 specific primers. p53 expression was determined at the protein level by Western blotting on protein extracts and at RNA level by Northern blotting. There was no p53 overexpression or mutation detectable in the protein extracts. Three of 65 (4.6%) of the carcinomas were positive for p53 by immunostaining with the polyclonal antibody CM1. Overexpression at the RNA level was detected in 2 of 32 (6.3%) carcinomas. p53 mutation was screened for by PCR/SSCP (single strand conformation polymorphism) followed by sequencing to define the site of mutation. Two of the cervical cancers (2.0%) showed mutation in p53 in exons 7 or 8. The mutation rate in HPV positive tumours was 1.2% (1/81) and in HPV negative tumours was 5.2% (1/19). p53 overexpression or mutation does not seem to play a significant role in cervical carcinomas.

Classification of TP53 mutations and HPV predict survival in advanced larynx cancer.

PubMed

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

2016-09-01

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

p53 genes function to restrain mobile elements

PubMed Central

Wylie, Annika; Jones, Amanda E.; D'Brot, Alejandro; Lu, Wan-Jin; Kurtz, Paula; Moran, John V.; Rakheja, Dinesh; Chen, Kenneth S.; Hammer, Robert E.; Comerford, Sarah A.; Amatruda, James F.; Abrams, John M.

2016-01-01

Throughout the animal kingdom, p53 genes govern stress response networks by specifying adaptive transcriptional responses. The human member of this gene family is mutated in most cancers, but precisely how p53 functions to mediate tumor suppression is not well understood. Using Drosophila and zebrafish models, we show that p53 restricts retrotransposon activity and genetically interacts with components of the piRNA (piwi-interacting RNA) pathway. Furthermore, transposon eruptions occurring in the p53− germline were incited by meiotic recombination, and transcripts produced from these mobile elements accumulated in the germ plasm. In gene complementation studies, normal human p53 alleles suppressed transposons, but mutant p53 alleles from cancer patients could not. Consistent with these observations, we also found patterns of unrestrained retrotransposons in p53-driven mouse and human cancers. Furthermore, p53 status correlated with repressive chromatin marks in the 5′ sequence of a synthetic LINE-1 element. Together, these observations indicate that ancestral functions of p53 operate through conserved mechanisms to contain retrotransposons. Since human p53 mutants are disabled for this activity, our findings raise the possibility that p53 mitigates oncogenic disease in part by restricting transposon mobility. PMID:26701264

Possible relevance of tumor-related genes mutation to malignant transformation of endometriosis.

PubMed

Ma, X; Hui, Y; Lin, L; Wu, Y; Zhang, X; Qin, X

2016-01-01

Despite studies have suggested that endometriosis has malignant potential, the molecular mechanism underlying the malignant transformation of endometriosis is poorly understood so far. Endometriosis-associated ovarian cancer (EAOC) or ovarian cancer arising from endometriosis (OCEM) may provide an ideal model for genetic studies. To investigate the genetic alterations during transformation of ovarian endometriosis into cancer, the authors analysed mutations of tumour-related genes (PTEN and p53) in EAOC cases (n=23, group 1), including 19 cases which were detected co-existence of endometriosis and cancer and four cases which fulfilled the histological criteria in malignant transformation of endometriosis (OCEMs), and in atypical hyperplasia ovarian endometriosis (aEMs) (n = 10, group 2), as well as in solitary ovarian endometriosis (EMs) (n = 20, group 3), simultaneously, to study the correlation of the two genes in the development and progression of the ovarian endometriosis malignancy. Each paraffin block was sliced into serial ten-µm-thick sections. Extracted DNA was amplified by nested PCR. Mutations of PTEN and p53 were examined by bidirectional DNA sequencing. It was acknowledged by experiments that the PTEN and p53 mutation frequency in EAOCs were significantly higher than that in aEMs and EMs. There was significant difference to compare EAOCs with EMs (p < 0.01, p < 0.05), and converse to compare with aEMs (p > 0.05), respectively. No definite involvement between the frequency of PTEN and p53 mutations in EAOCs and age difference, histological type, clinical stage, pathological grade, and whether accompanied by metastasis (p > 0.05); however, a decreasing trend of PTEN mutation with the increased age, decreased clinical stage and pathological grade, and when accompanied by metastasis was detected. Adversely, an increasing trend of p53 mutation was represented. In EAOCs group, the authors detected eight PTEN and four p53 mutation events, respectively. Moreover, one case occurred PTEN and p53 mutation simultaneously. With 23 EAOCs, two cases which fulfilled the histological criteria in malignant transformation of endometriosis, which may be a specific entity distinct from non-endometriosis-associated ovarian cancer, the authors named them the OCEMs, occurred PTEN or p53 mutation, respectively. The present study suggested that the mutation and functional incapacitation of certain tumor-related genes may be involved in malignant transformation of endometriosis. PTEN mutation is the pristine event, but p53 mutation is the late.

Promoter hypermethylation of the DNA repair gene O(6)-methylguanine-DNA methyltransferase is associated with the presence of G:C to A:T transition mutations in p53 in human colorectal tumorigenesis.

PubMed

Esteller, M; Risques, R A; Toyota, M; Capella, G; Moreno, V; Peinado, M A; Baylin, S B; Herman, J G

2001-06-15

Defects in DNA repair may be responsible for the genesis of mutations in key genes in cancer cells. The tumor suppressor gene p53 is commonly mutated in human cancer by missense point mutations, most of them G:C to A:T transitions. A recognized cause for this type of change is spontaneous deamination of the methylcytosine. However, the persistence of a premutagenic O(6)-methylguanine can also be invoked. This last lesion is removed in the normal cell by the DNA repair enzyme O(6)-methylguanine-DNA methyltransferase (MGMT). In many tumor types, epigenetic silencing of MGMT by promoter hypermethylation has been demonstrated and linked to the appearance of G to A mutations in the K-ras oncogene in colorectal tumors. To study the relevance of defective MGMT function by aberrant methylation in relation to the presence of p53 mutations, we studied 314 colorectal tumors for MGMT promoter hypermethylation and p53 mutational spectrum. Inactivation of MGMT by aberrant methylation was associated with the appearance of G:C to A:T transition mutations at p53 (Fischer's exact test, two-tailed; P = 0.01). Overall, MGMT methylated tumors displayed p53 transition mutations in 43 of 126 (34%) cases, whereas MGMT unmethylated tumors only showed G:C to A:T changes in 37 of 188 (19%) tumors. A more striking association was found in G:C to A:T transitions in non-CpG dinucleotides; 71% (12 of 17) of the total non-CpG transition mutations in p53 were observed in MGMT aberrantly methylated tumors (Fischer's exact test, two-tailed; P = 0.008). Our data suggest that epigenetic silencing of MGMT by promoter hypermethylation may lead to G:C to A:T transition mutations in p53.

Multiple primary tumors of the upper aerodigestive tract: is there a role for constitutional mutations in the p53 gene?

PubMed

Gallo, O; Sardi, I; Pepe, G; Franchi, A; Attanasio, M; Giusti, B; Bocciolini, C; Abbate, R

1999-07-19

Head-and-neck cancer (HNC) patients have a high risk of developing second primary tumors of the upper aerodigestive tract, the main cause of death. Although the roles of tobacco and diet in multiple head-and-neck carcinogenesis have been thoroughly investigated, little is known about individual genetic susceptibility factors involved in this process. Genomic instability, reflecting the propensity and the susceptibility of the genome to acquire multiple alterations, could be considered a driving force behind multiple carcinogenesis. Mutation of the p53 tumor-suppressor gene has been proposed to play an important role in this process. Therefore, we evaluated the incidence of inherited p53 germ-line alteration(s) in a population of 24 consecutive HNC patients and their first-degree relatives affected by multiple malignancies as well as the occurrence of p53 somatic acquired mutation(s) in 16 cancers, including first and second primaries from 5 HNCs of the same group. Mutations in exons 4-11 of the p53 gene were investigated using SSCP-PCR analysis and DNA sequencing. Analysis was extended to the peripheral blood and cancer biopsies available from first-degree relatives of cancer-prone families with p53 germ-line mutations. p53 germ-line mutations were identified in the peripheral blood and corresponding cancers of 3 HNC patients who had multiple malignancies. The only missense mutation detected was mapped in exon 6; it is a GTG to GAG substitution with an amino acid change from Val to Glu at codon 197. The remaining 2 p53 germ-line mutations were single-nucleotide substitutions without amino acid change in exon 6 (codon 213, CGA to CGG) and in exon 8 (codon 295, CCT to CCC), respectively. These mutations were found in HNC patients with a family history of cancer. Abnormal expression of wild-type p53 protein in normal and pathological tissues from patients with the same sense single-nucleotide substitutions was detected by immuno-histochemistry.

SIRT1 inhibition restores apoptotic sensitivity in p53-mutated human keratinocytes

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

Herbert, Katharine J.; Cook, Anthony L., E-mail: Anthony.Cook@utas.edu.au; Snow, Elizabeth T., E-mail: elizabeth.snow@utas.edu.au

2014-06-15

Mutations to the p53 gene are common in UV-exposed keratinocytes and contribute to apoptotic resistance in skin cancer. P53-dependent activity is modulated, in part, by a complex, self-limiting feedback loop imposed by miR-34a-mediated regulation of the lysine deacetylase, SIRT1. Expression of numerous microRNAs is dysregulated in squamous and basal cell carcinomas; however the contribution of specific microRNAs to the pathogenesis of skin cancer remains untested. Through use of RNAi, miRNA target site blocking oligonucleotides and small molecule inhibitors, this study explored the influence of p53 mutational status, SIRT1 activity and miR-34a levels on apoptotic sensitivity in primary (NHEK) and p53-mutatedmore » (HaCaT) keratinocyte cell lines. SIRT1 and p53 are overexpressed in p53-mutated keratinocytes, whilst miR-34a levels are 90% less in HaCaT cells. HaCaTs have impaired responses to p53/SIRT1/miR-34a axis manipulation which enhanced survival during exposure to the chemotherapeutic agent, camptothecin. Inhibition of SIRT1 activity in this cell line increased p53 acetylation and doubled camptothecin-induced cell death. Our results demonstrate that p53 mutations increase apoptotic resistance in keratinocytes by interfering with miR-34a-mediated regulation of SIRT1 expression. Thus, SIRT1 inhibitors may have a therapeutic potential for overcoming apoptotic resistance during skin cancer treatment. - Highlights: • Impaired microRNA biogenesis promotes apoptotic resistance in HaCaT keratinocytes. • TP53 mutations suppress miR-34a-mediated regulation of SIRT1 expression. • SIRT1 inhibition increases p53 acetylation in HaCaTs, restoring apoptosis.« less

A novel dysfunctional germline P53 mutation identified in a family with Li-Fraumeni syndrome.

PubMed

Ji, Min; Wang, Lin; Shao, Yuguo; Cao, Wei; Xu, Ting; Chen, Shujie; Wang, Zhiwei; He, Qi; Yang, Kuo

2018-01-01

Li-Fraumeni Syndrome (LFS), which is a rare dominantly inherited cancer predisposition syndrome, is associated with germline P53 mutations. Mutations of the tumor suppressor protein P53 are associated with more than 50% of human cancers; however, almost 30% of P53 mutations occur rarely and this has raised questions about their significance. It therefore appeared of particular interest that we identified a novel mutation in a patient suffering from breast cancer and fulfilling the diagnostic criteria of LFS. In this study, a patient with remarkable family history developed breast cancer and was diagnosed with LFS. By performing next-generation sequencing on the patient and subsequent verification by Sanger sequencing among other family members, a new germ-line P53 replication error, a trinucleotide repeat mutation in the coding region, was identified in two generations of this Li-Fraumeni family.

A meta-analysis of the relationship between FGFR3 and TP53 mutations in bladder cancer.

PubMed

Neuzillet, Yann; Paoletti, Xavier; Ouerhani, Slah; Mongiat-Artus, Pierre; Soliman, Hany; de The, Hugues; Sibony, Mathilde; Denoux, Yves; Molinie, Vincent; Herault, Aurélie; Lepage, May-Linda; Maille, Pascale; Renou, Audrey; Vordos, Dimitri; Abbou, Claude-Clément; Bakkar, Ashraf; Asselain, Bernard; Kourda, Nadia; El Gaaied, Amel; Leroy, Karen; Laplanche, Agnès; Benhamou, Simone; Lebret, Thierry; Allory, Yves; Radvanyi, François

2012-01-01

TP53 and FGFR3 mutations are the most common mutations in bladder cancers. FGFR3 mutations are most frequent in low-grade low-stage tumours, whereas TP53 mutations are most frequent in high-grade high-stage tumours. Several studies have reported FGFR3 and TP53 mutations to be mutually exclusive events, whereas others have reported them to be independent. We carried out a meta-analysis of published findings for FGFR3 and TP53 mutations in bladder cancer (535 tumours, 6 publications) and additional unpublished data for 382 tumours. TP53 and FGFR3 mutations were not independent events for all tumours considered together (OR = 0.25 [0.18-0.37], p = 0.0001) or for pT1 tumours alone (OR = 0.47 [0.28-0.79], p = 0.0009). However, if the analysis was restricted to pTa tumours or to muscle-invasive tumours alone, FGFR3 and TP53 mutations were independent events (OR = 0.56 [0.23-1.36] (p = 0.12) and OR = 0.99 [0.37-2.7] (p = 0.35), respectively). After stratification of the tumours by stage and grade, no dependence was detected in the five tumour groups considered (pTaG1 and pTaG2 together, pTaG3, pT1G2, pT1G3, pT2-4). These differences in findings can be attributed to the putative existence of two different pathways of tumour progression in bladder cancer: the CIS pathway, in which FGFR3 mutations are rare, and the Ta pathway, in which FGFR3 mutations are frequent. TP53 mutations occur at the earliest stage of the CIS pathway, whereas they occur would much later in the Ta pathway, at the T1G3 or muscle-invasive stage.

A Meta-Analysis of the Relationship between FGFR3 and TP53 Mutations in Bladder Cancer

PubMed Central

Ouerhani, Slah; Mongiat-Artus, Pierre; Soliman, Hany; de The, Hugues; Sibony, Mathilde; Denoux, Yves; Molinie, Vincent; Herault, Aurélie; Lepage, May-Linda; Maille, Pascale; Renou, Audrey; Vordos, Dimitri; Abbou, Claude-Clément; Bakkar, Ashraf; Asselain, Bernard; Kourda, Nadia; El Gaaied, Amel; Leroy, Karen; Laplanche, Agnès; Benhamou, Simone; Lebret, Thierry; Allory, Yves; Radvanyi, François

2012-01-01

TP53 and FGFR3 mutations are the most common mutations in bladder cancers. FGFR3 mutations are most frequent in low-grade low-stage tumours, whereas TP53 mutations are most frequent in high-grade high-stage tumours. Several studies have reported FGFR3 and TP53 mutations to be mutually exclusive events, whereas others have reported them to be independent. We carried out a meta-analysis of published findings for FGFR3 and TP53 mutations in bladder cancer (535 tumours, 6 publications) and additional unpublished data for 382 tumours. TP53 and FGFR3 mutations were not independent events for all tumours considered together (OR = 0.25 [0.18–0.37], p = 0.0001) or for pT1 tumours alone (OR = 0.47 [0.28–0.79], p = 0.0009). However, if the analysis was restricted to pTa tumours or to muscle-invasive tumours alone, FGFR3 and TP53 mutations were independent events (OR = 0.56 [0.23–1.36] (p = 0.12) and OR = 0.99 [0.37–2.7] (p = 0.35), respectively). After stratification of the tumours by stage and grade, no dependence was detected in the five tumour groups considered (pTaG1 and pTaG2 together, pTaG3, pT1G2, pT1G3, pT2-4). These differences in findings can be attributed to the putative existence of two different pathways of tumour progression in bladder cancer: the CIS pathway, in which FGFR3 mutations are rare, and the Ta pathway, in which FGFR3 mutations are frequent. TP53 mutations occur at the earliest stage of the CIS pathway, whereas they occur would much later in the Ta pathway, at the T1G3 or muscle-invasive stage. PMID:23272046

Analysis of p53 gene mutations in human gliomas by polymerase chain reaction-based single-strand conformation polymorphism and DNA sequencing.

PubMed

Sarkar, F H; Kupsky, W J; Li, Y W; Sreepathi, P

1994-03-01

Mutations in the p53 gene have been recognized in brain tumors, and clonal expansion of p53 mutant cells has been shown to be associated with glioma progression. However, studies on the p53 gene have been limited by the need for frozen tissues. We have developed a method utilizing polymerase chain reaction (PCR) for the direct analysis of p53 mutation by single-strand conformation polymorphism (SSCP) and by direct DNA sequencing of the p53 gene using a single 10-microns paraffin-embedded tissue section. We applied this method to screen for p53 gene mutations in exons 5-8 in human gliomas utilizing paraffin-embedded tissues. Twenty paraffin blocks containing tumor were selected from surgical specimens from 17 different adult patients. Tumors included six anaplastic astrocytomas (AAs), nine glioblastomas (GBs), and two mixed malignant gliomas (MMGs). The tissue section on the stained glass slide was used to guide microdissection of an unstained adjacent tissue section to ensure > 90% of the tumor cell population for p53 mutational analysis. Simultaneously, microdissection of the tissue was also carried out to obtain normal tissue from adjacent areas as a control. Mutations in the p53 gene were identified in 3 of 17 (18%) patients by PCR-SSCP analysis and subsequently confirmed by PCR-based DNA sequencing. Mutations in exon 5 resulting in amino acid substitution were found in one thalamic AA (codon 158, CGC > CTT: Arg > Leu) and one cerebral hemispheric GB (codon 151, CCG > CTG: Pro > Leu).(ABSTRACT TRUNCATED AT 250 WORDS)

Distinct tumor protein p53 mutants in breast cancer subgroups.

PubMed

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

2013-03-01

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

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

PubMed Central

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

2015-01-01

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

Correlation of MET gene amplification and TP53 mutation with PD-L1 expression in non-small cell lung cancer

PubMed Central

Albitar, Maher; Sudarsanam, Sucha; Ma, Wanlong; Jiang, Shiping; Chen, Wayne; Funari, Vincent; Blocker, Forrest; Agersborg, Sally

2018-01-01

Background The role of MET amplification in lung cancer, particularly in relation to checkpoint inhibition and EGFR WT, has not been fully explored. In this study, we correlated PD-L1 expression with MET amplification and EGFR, KRAS, or TP53 mutation in primary lung cancer. Methods In this retrospective study, tissue collected from 471 various tumors, including 397 lung cancers, was tested for MET amplification by FISH with a MET/centromere probe. PD-L1 expression was evaluated using clone SP142 and standard immunohistochemistry, and TP53, KRAS, and EGFR mutations were tested using next generation sequencing. Results Our results revealed that PD-L1 expression in non-small cell lung cancer is inversely correlated with EGFR mutation (P=0.0003), and positively correlated with TP53 mutation (P=0.0001) and MET amplification (P=0.004). Patients with TP53 mutations had significantly higher MET amplification (P=0.007), and were more likely (P=0.0002) to be EGFR wild type. There was no correlation between KRAS mutation and overall PD-L1 expression, but significant positive correlation between PD-L1 expression and KRAS with TP53 co-mutation (P=0.0002). A cut-off for the ratio of MET: centromere signal was determined as 1.5%, and 4% of lung cancer patients were identified as MET amplified. Conclusions This data suggests that in lung cancer both MET and TP53 play direct roles in regulating PD-L1 opposing EGFR. Moreover, KRAS and TP53 co-mutation may cooperate to drive PD-L1 expression in lung cancer. Adding MET or TP53 inhibitors to checkpoint inhibitors may be an attractive combination therapy in patients with lung cancer and MET amplification. PMID:29568386

The Ovary Is an Alternative Site of Origin for High-Grade Serous Ovarian Cancer in Mice

PubMed Central

Coffey, Donna M.; Ma, Lang; Matzuk, Martin M.

2015-01-01

Although named “ovarian cancer,” it has been unclear whether the cancer actually arises from the ovary, especially for high-grade serous carcinoma (HGSC), also known as high-grade serous ovarian cancer, the most common and deadliest ovarian cancer. In addition, the tumor suppressor p53 is the most frequently mutated gene in HGSC. However, whether mutated p53 can cause HGSC remains unknown. In this study, we bred a p53 mutation, p53R172H, into conditional Dicer-Pten double-knockout (DKO) mice, a mouse model duplicating human HGSC, to generate triple-mutant (TKO) mice. Like DKO mice, these TKO mice develop metastatic HGSCs originating from the fallopian tube. Unlike DKO mice, however, even after fallopian tubes are removed in TKO mice, ovaries alone can develop metastatic HGSCs, indicating that a p53 mutation can drive HGSC arising from the ovary. To confirm this, we generated p53R172H-Pten double-mutant mice, one of the genetic control lines for TKO mice. As anticipated, these double-mutant mice also develop metastatic HGSCs from the ovary, verifying the HGSC-forming ability of ovaries with a p53 mutation. Our study therefore shows that ovaries harboring a p53 mutation, as well as fallopian tubes, can be a distinct tissue source of high-grade serous ovarian cancer in mice. PMID:25815421

The ovary is an alternative site of origin for high-grade serous ovarian cancer in mice.

PubMed

Kim, Jaeyeon; Coffey, Donna M; Ma, Lang; Matzuk, Martin M

2015-06-01

Although named "ovarian cancer," it has been unclear whether the cancer actually arises from the ovary, especially for high-grade serous carcinoma (HGSC), also known as high-grade serous ovarian cancer, the most common and deadliest ovarian cancer. In addition, the tumor suppressor p53 is the most frequently mutated gene in HGSC. However, whether mutated p53 can cause HGSC remains unknown. In this study, we bred a p53 mutation, p53(R172H), into conditional Dicer-Pten double-knockout (DKO) mice, a mouse model duplicating human HGSC, to generate triple-mutant (TKO) mice. Like DKO mice, these TKO mice develop metastatic HGSCs originating from the fallopian tube. Unlike DKO mice, however, even after fallopian tubes are removed in TKO mice, ovaries alone can develop metastatic HGSCs, indicating that a p53 mutation can drive HGSC arising from the ovary. To confirm this, we generated p53(R172H)-Pten double-mutant mice, one of the genetic control lines for TKO mice. As anticipated, these double-mutant mice also develop metastatic HGSCs from the ovary, verifying the HGSC-forming ability of ovaries with a p53 mutation. Our study therefore shows that ovaries harboring a p53 mutation, as well as fallopian tubes, can be a distinct tissue source of high-grade serous ovarian cancer in mice.

Binding of Amphipathic Cell Penetrating Peptide p28 to Wild Type and Mutated p53 as studied by Raman, Atomic Force and Surface Plasmon Resonance spectroscopies.

PubMed

Signorelli, Sara; Santini, Simona; Yamada, Tohru; Bizzarri, Anna Rita; Beattie, Craig W; Cannistraro, Salvatore

2017-04-01

Mutations within the DNA binding domain (DBD) of the tumor suppressor p53 are found in >50% of human cancers and may significantly modify p53 secondary structure impairing its function. p28, an amphipathic cell-penetrating peptide, binds to the DBD through hydrophobic interaction and induces a posttranslational increase in wildtype and mutant p53 restoring functionality. We use mutation analyses to explore which elements of secondary structure may be critical to p28 binding. Molecular modeling, Raman spectroscopy, Atomic Force Spectroscopy (AFS) and Surface Plasmon Resonance (SPR) were used to identify which secondary structure of site-directed and naturally occurring mutant DBDs are potentially altered by discrete changes in hydrophobicity and the molecular interaction with p28. We show that specific point mutations that alter hydrophobicity within non-mutable and mutable regions of the p53 DBD alter specific secondary structures. The affinity of p28 was positively correlated with the β-sheet content of a mutant DBD, and reduced by an increase in unstructured or random coil that resulted from a loss in hydrophobicity and redistribution of surface charge. These results help refine our knowledge of how mutations within p53-DBD alter secondary structure and provide insight on how potential structural alterations in p28 or similar molecules improve their ability to restore p53 function. Raman spectroscopy, AFS, SPR and computational modeling are useful approaches to characterize how mutations within the p53DBD potentially affect secondary structure and identify those structural elements prone to influence the binding affinity of agents designed to increase the functionality of p53. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular and immunohistochemical analysis of P53 in phaeochromocytoma.

PubMed Central

Dahia, P. L.; Aguiar, R. C.; Tsanaclis, A. M.; Bendit, I.; Bydlowski, S. P.; Abelin, N. M.; Toledo, S. P.

1995-01-01

We searched for mutations of the p53 gene in 25 phaeochromocytomas using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis of the entire conserved region of the gene, encompassing exons 4-8; expression of the p53 protein was assessed by immunohistochemistry. No mutations were found, while a polymorphism in codon 72 was observed. Immunohistochemistry revealed nuclear p53 overexpression in one tumour sample. We conclude that mutations of the 'hotspot' region of the p53 gene do not seem to play a role in the pathogenesis of phaeochromocytoma. Images Figure 1 Figure 2 Figure 3 PMID:7577469

Association between smoking and p53 mutation in lung cancer: a meta-analysis.

PubMed

Liu, X; Lin, X J; Wang, C P; Yan, K K; Zhao, L Y; An, W X; Liu, X D

2014-01-01

To carry out a meta-analysis on the relationship between smoking and p53 gene mutation in lung cancer patients. PubMed, Web of Science, ProQest and Medline were searched by using the key words: 'lung cancer or lung neoplasm or lung carcinoma', 'p53 mutation' and 'smoking'. According to the selection criteria, 15 articles were identified and methodologically analysed by stata 12.0 software package. Crude odds ratios with 95% confidence intervals calculated using the fixed-effects model were used to assess the strength of association between smoking and p53 mutation in lung cancer. In total, 15 articles with 1770 lung cancer patients were identified; 69.6% of the patients were smokers, 30.4% were non-smokers. Overall, smokers with lung cancer had a 2.70-fold (95% confidence interval 2.04-3.59) higher risk for mutation than the non-smokers with lung cancer. In subgroup analyses, the increased risk of p53 mutation in smokers than in non-smokers was found in the non-small cell lung cancer (NSCLC) group (odds ratio = 2.38, 95% confidence interval = 1.71-3.32) and in the NSCLC and SCLC group (odds ratio = 3.82, 95% confidence interval = 2.19-6.69). This meta-analysis strongly suggests that p53 mutation is associated with smoking-induced lung cancer. Smokers with lung cancer had a higher risk for p53 mutation than non-smokers. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

P16 UV mutations in human skin epithelial tumors.

PubMed

Soufir, N; Molès, J P; Vilmer, C; Moch, C; Verola, O; Rivet, J; Tesniere, A; Dubertret, L; Basset-Seguin, N

1999-09-23

The p16 gene expresses two alternative transcripts (p16alpha and p16beta) involved in tumor suppression via the retinoblastoma (Rb) or p53 pathways. Disruption of these pathways can occur through inactivation of p16 or p53, or activating mutations of cyclin dependant kinase 4 gene (Cdk4). We searched for p16, Cdk4 and p53 gene mutations in 20 squamous cell carcinomas (SSCs), 1 actinic keratosis (AK), and 28 basal cell carcinomas (BCCs), using PCR-SSCP. A deletion and methylation analysis of p16 was also performed. Six different mutations (12%) were detected in exon 2 of p16 (common to p16alpha and p16beta), in five out of 21 squamous lesions (24%) (one AK and four SCCs) and one out of 28 BCCs (3.5%). These included four (66%) ultraviolet (UV)-type mutations (two tandems CC : GG to TT : AA transitions and two C : G to T : A transitions at dipyrimidic site) and two transversions. P53 mutations were present in 18 samples (37%), mostly of UV type. Of these, only two (one BCC and one AK) harboured simultaneously mutations of p16, but with no consequence on p16beta transcript. Our data demonstrate for the first time the presence of p16 UV induced mutations in non melanoma skin cancer, particularly in the most aggressive SCC type, and support that p16 and p53 are involved in two independent pathways in skin carcinogenesis.

Neoplasia of the ampulla of Vater. Ki-ras and p53 mutations.

PubMed Central

Scarpa, A.; Capelli, P.; Zamboni, G.; Oda, T.; Mukai, K.; Bonetti, F.; Martignoni, G.; Iacono, C.; Serio, G.; Hirohashi, S.

1993-01-01

Eleven tumors of the ampulla of Vater (5 stage IV and 2 stage II adenocarcinomas, 1 stage II papillary carcinoma, 1 neuroendocrine carcinoma, and 2 adenomas, one with foci of carcinoma) were examined for Ki-ras and p53 gene mutations by single-strand conformation polymorphism analysis and direct sequencing of polymerase chain reaction-amplified DNA fragments. Ki-ras mutations were found in one adenocarcinoma and in the adenoma with foci of carcinoma, both involving mainly the intraduodenal bile duct component of the ampulla. Seven cases showed p53 gene mutations: four advanced-stage adenocarcinomas, the papillary carcinoma, the neuroendocrine carcinoma, and the adenoma with foci of carcinoma. Nuclear accumulation of p53 protein was immunohistochemically detected in the morphologically high-grade areas of the five cancers harboring a p53 gene missense point mutation. The adenomas, the two frame shift-mutated cancers, and the adenomatous and low-grade cancer areas of mutated carcinomas were immunohistochemically negative. Our data suggest that in ampullary neoplasia 1) p53 mutations are common abnormalities associated with the transformation of adenomas and low-grade cancers into morphologically high-grade carcinomas, and 2) Ki-ras mutations are relatively less frequent and might be restricted to tumors originating from the bile duct component of the ampulla. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:8475992

Evolutionary Action score of TP53 (EAp53) identifies high risk mutations associated with decreased survival and increased distant metastases in head and neck cancer

PubMed Central

Neskey, David M.; Osman, Abdullah A.; Ow, Thomas J.; Katsonis, Panagiotis; McDonald, Thomas; Hicks, Stephanie C.; Hsu, Teng-Kuei; Pickering, Curtis R.; Ward, Alexandra; Patel, Ameeta; Yordy, John S.; Skinner, Heath D.; Giri, Uma; Sano, Daisuke; Story, Michael D.; Beadle, Beth M.; El-Naggar, Adel K.; Kies, Merrill S.; William, William N.; Caulin, Carlos; Frederick, Mitchell; Kimmel, Marek; Myers, Jeffrey N.; Lichtarge, Olivier

2015-01-01

TP53 is the most frequently altered gene in head and neck squamous cell carcinoma (HNSCC) with mutations occurring in over two third of cases, but the prognostic significance of these mutations remains elusive. In the current study, we evaluated a novel computational approach termed Evolutionary Action (EAp53) to stratify patients with tumors harboring TP53 mutations as high or low risk, and validated this system in both in vivo and in vitro models. Patients with high risk TP53 mutations had the poorest survival outcomes and the shortest time to the development of distant metastases. Tumor cells expressing high risk TP53 mutations were more invasive and tumorigenic and they exhibited a higher incidence of lung metastases. We also documented an association between the presence of high risk mutations and decreased expression of TP53 target genes, highlighting key cellular pathways that are likely to be dysregulated by this subset of p53 mutations which confer particularly aggressive tumor behavior. Overall, our work validated EAp53 as a novel computational tool that may be useful in clinical prognosis of tumors harboring p53 mutations. PMID:25634208

Low expression levels of ATM may substitute for CHEK2 /TP53 mutations predicting resistance towards anthracycline and mitomycin chemotherapy in breast cancer.

PubMed

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

2012-03-15

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

Insight into a novel p53 single point mutation (G389E) by Molecular Dynamics Simulations.

PubMed

Pirolli, Davide; Carelli Alinovi, Cristiana; Capoluongo, Ettore; Satta, Maria Antonia; Concolino, Paola; Giardina, Bruno; De Rosa, Maria Cristina

2010-12-30

The majority of inactivating mutations of p53 reside in the central core DNA binding domain of the protein. In this computational study, we investigated the structural effects of a novel p53 mutation (G389E), identified in a patient with congenital adrenal hyperplasia, which is located within the extreme C-terminal domain (CTD) of p53, an unstructured, flexible region (residues 367-393) of major importance for the regulation of the protein. Based on the three-dimensional structure of a carboxyl-terminal peptide of p53 in complex with the S100B protein, which is involved in regulation of the tumor suppressor activity, a model of wild type (WT) and mutant extreme CTD was developed by molecular modeling and molecular dynamics simulation. It was found that the G389E amino acid replacement has negligible effects on free p53 in solution whereas it significantly affects the interactions of p53 with the S100B protein. The results suggest that the observed mutation may interfere with p53 transcription activation and provide useful information for site-directed mutagenesis experiments.

Mutant p53-Expressing Cells Undergo Necroptosis via Cell Competition with the Neighboring Normal Epithelial Cells.

PubMed

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

2018-06-26

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

Clinical implications of genomic profiles in metastatic breast cancer with a focus on TP53 and PIK3CA, the most frequently mutated genes.

PubMed

Kim, Ji-Yeon; Lee, Eunjin; Park, Kyunghee; Park, Woong-Yang; Jung, Hae Hyun; Ahn, Jin Seok; Im, Young-Hyuck; Park, Yeon Hee

2017-04-25

Breast cancer (BC) has been genetically profiled through large-scale genome analyses. However, the role and clinical implications of genetic alterations in metastatic BC (MBC) have not been evaluated. Therefore, we conducted whole-exome sequencing (WES) and RNA-Seq of 37 MBC samples and targeted deep sequencing of another 29 MBCs. We evaluated somatic mutations from WES and targeted sequencing and assessed gene expression and performed pathway analysis from RNA-Seq. In this analysis, PIK3CA was the most commonly mutated gene in estrogen receptor (ER)-positive BC, while in ER-negative BC, TP53 was the most commonly mutated gene (p = 0.018 and p < 0.001, respectively). TP53 stopgain/loss and frameshift mutation was related to low expression of TP53 in contrast nonsynonymous mutation was related to high expression. The impact of TP53 mutation on clinical outcome varied with regard to ER status. In ER-positive BCs, wild type TP53 had a better prognosis than mutated TP53 (median overall survival (OS) (wild type vs. mutated): 88.5 ± 54.4 vs. 32.6 ± 10.7 (months), p = 0.002). In contrast, mutated TP53 had a protective effect in ER-negative BCs (median OS: 0.10 vs. 32.6 ± 8.2, p = 0.026). However, PIK3CA mutation did not affect patient survival. In gene expression analysis, CALM1, a potential regulator of AKT, was highly expressed in PIK3CA-mutated BCs. In conclusion, mutation of TP53 was associated with expression status and affect clinical outcome according to ER status in MBC. Although mutation of PIK3CA was not related to survival in this study, mutation of PIK3CA altered the expression of other genes and pathways including CALM1 and may be a potential predictive marker of PI3K inhibitor effectiveness.

TP53 Mutational Status Is a Potential Marker for Risk Stratification in Wilms Tumour with Diffuse Anaplasia

PubMed Central

Chagtai, Tasnim; Popov, Sergey D.; Sebire, Neil J.; Vujanic, Gordan; Perlman, Elizabeth; Anderson, James R.; Grundy, Paul; Dome, Jeffrey S.; Pritchard-Jones, Kathy

2014-01-01

Purpose The presence of diffuse anaplasia in Wilms tumours (DAWT) is associated with TP53 mutations and poor outcome. As patients receive intensified treatment, we sought to identify whether TP53 mutational status confers additional prognostic information. Patients and Methods We studied 40 patients with DAWT with anaplasia in the tissue from which DNA was extracted and analysed for TP53 mutations and 17p loss. The majority of cases were profiled by copy number (n = 32) and gene expression (n = 36) arrays. TP53 mutational status was correlated with patient event-free and overall survival, genomic copy number instability and gene expression profiling. Results From the 40 cases, 22 (55%) had TP53 mutations (2 detected only after deep-sequencing), 20 of which also had 17p loss (91%); 18 (45%) cases had no detectable mutation but three had 17p loss. Tumours with TP53 mutations and/or 17p loss (n = 25) had an increased risk of recurrence as a first event (p = 0.03, hazard ratio (HR), 3.89; 95% confidence interval (CI), 1.26–16.0) and death (p = 0.04, HR, 4.95; 95% CI, 1.36–31.7) compared to tumours lacking TP53 abnormalities. DAWT carrying TP53 mutations showed increased copy number alterations compared to those with wild-type, suggesting a more unstable genome (p = 0.03). These tumours showed deregulation of genes associated with cell cycle and DNA repair biological processes. Conclusion This study provides evidence that TP53 mutational analysis improves risk stratification in DAWT. This requires validation in an independent cohort before clinical use as a biomarker. PMID:25313908

TP53 mutational status is a potential marker for risk stratification in Wilms tumour with diffuse anaplasia.

PubMed

Maschietto, Mariana; Williams, Richard D; Chagtai, Tasnim; Popov, Sergey D; Sebire, Neil J; Vujanic, Gordan; Perlman, Elizabeth; Anderson, James R; Grundy, Paul; Dome, Jeffrey S; Pritchard-Jones, Kathy

2014-01-01

The presence of diffuse anaplasia in Wilms tumours (DAWT) is associated with TP53 mutations and poor outcome. As patients receive intensified treatment, we sought to identify whether TP53 mutational status confers additional prognostic information. We studied 40 patients with DAWT with anaplasia in the tissue from which DNA was extracted and analysed for TP53 mutations and 17p loss. The majority of cases were profiled by copy number (n = 32) and gene expression (n = 36) arrays. TP53 mutational status was correlated with patient event-free and overall survival, genomic copy number instability and gene expression profiling. From the 40 cases, 22 (55%) had TP53 mutations (2 detected only after deep-sequencing), 20 of which also had 17p loss (91%); 18 (45%) cases had no detectable mutation but three had 17p loss. Tumours with TP53 mutations and/or 17p loss (n = 25) had an increased risk of recurrence as a first event (p = 0.03, hazard ratio (HR), 3.89; 95% confidence interval (CI), 1.26-16.0) and death (p = 0.04, HR, 4.95; 95% CI, 1.36-31.7) compared to tumours lacking TP53 abnormalities. DAWT carrying TP53 mutations showed increased copy number alterations compared to those with wild-type, suggesting a more unstable genome (p = 0.03). These tumours showed deregulation of genes associated with cell cycle and DNA repair biological processes. This study provides evidence that TP53 mutational analysis improves risk stratification in DAWT. This requires validation in an independent cohort before clinical use as a biomarker.

Evolutionary Action Score of TP53 Identifies High-Risk Mutations Associated with Decreased Survival and Increased Distant Metastases in Head and Neck Cancer.

PubMed

Neskey, David M; Osman, Abdullah A; Ow, Thomas J; Katsonis, Panagiotis; McDonald, Thomas; Hicks, Stephanie C; Hsu, Teng-Kuei; Pickering, Curtis R; Ward, Alexandra; Patel, Ameeta; Yordy, John S; Skinner, Heath D; Giri, Uma; Sano, Daisuke; Story, Michael D; Beadle, Beth M; El-Naggar, Adel K; Kies, Merrill S; William, William N; Caulin, Carlos; Frederick, Mitchell; Kimmel, Marek; Myers, Jeffrey N; Lichtarge, Olivier

2015-04-01

TP53 is the most frequently altered gene in head and neck squamous cell carcinoma, with mutations occurring in over two-thirds of cases, but the prognostic significance of these mutations remains elusive. In the current study, we evaluated a novel computational approach termed evolutionary action (EAp53) to stratify patients with tumors harboring TP53 mutations as high or low risk, and validated this system in both in vivo and in vitro models. Patients with high-risk TP53 mutations had the poorest survival outcomes and the shortest time to the development of distant metastases. Tumor cells expressing high-risk TP53 mutations were more invasive and tumorigenic and they exhibited a higher incidence of lung metastases. We also documented an association between the presence of high-risk mutations and decreased expression of TP53 target genes, highlighting key cellular pathways that are likely to be dysregulated by this subset of p53 mutations that confer particularly aggressive tumor behavior. Overall, our work validated EAp53 as a novel computational tool that may be useful in clinical prognosis of tumors harboring p53 mutations. ©2015 American Association for Cancer Research.

Smoking, p53 Mutation, and Lung Cancer

PubMed Central

Gibbons, Don L.; Byers, Lauren A.; Kurie, Jonathan M.

2014-01-01

This issue marks the 50th Anniversary of the release of the U.S. Surgeon General’s Report on Smoking and Health. Perhaps no other singular event has done more to highlight the effects of smoking on the development of cancer. Tobacco exposure is the leading cause of cancers involving the oral cavity, conductive airways and the lung. Owing to the many carcinogens in tobacco smoke, smoking-related malignancies have a high genome-wide burden of mutations, including in the gene encoding for p53. The p53 protein is the most frequently mutated tumor suppressor in cancer, responsible for a range of critical cellular functions that are compromised by the presence of a mutation. Herein we review the epidemiologic connection between tobacco exposure and cancer, the molecular basis of p53 mutation in lung cancer, and the normal molecular and cellular roles of p53 that are abrogated during lung tumor development and progression as defined by in vitro and in vivo studies. We also consider the therapeutic potential of targeting mutant p53 in a clinical setting based upon the cellular role of mutant p53 and data from genetic murine models. PMID:24442106

Ovarian and endometrial endometrioid carcinomas have distinct CTNNB1 and PTEN mutation profiles.

PubMed

McConechy, Melissa K; Ding, Jiarui; Senz, Janine; Yang, Winnie; Melnyk, Nataliya; Tone, Alicia A; Prentice, Leah M; Wiegand, Kimberly C; McAlpine, Jessica N; Shah, Sohrab P; Lee, Cheng-Han; Goodfellow, Paul J; Gilks, C Blake; Huntsman, David G

2014-01-01

Ovarian endometrioid carcinomas and endometrial endometrioid carcinomas share many histological and molecular alterations. These similarities are likely due to a common endometrial epithelial precursor cell of origin, with most ovarian endometrioid carcinomas arising from endometriosis. To directly compare the mutation profiles of two morphologically similar tumor types, endometrial endometrioid carcinomas (n=307) and ovarian endometrioid carcinomas (n=33), we performed select exon capture sequencing on a panel of genes: ARID1A, PTEN, PIK3CA, KRAS, CTNNB1, PPP2R1A, TP53. We found that PTEN mutations are more frequent in low-grade endometrial endometrioid carcinomas (67%) compared with low-grade ovarian endometrioid carcinomas (17%) (P<0.0001). By contrast, CTNNB1 mutations are significantly different in low-grade ovarian endometrioid carcinomas (53%) compared with low-grade endometrial endometrioid carcinomas (28%) (P<0.0057). This difference in CTNNB1 mutation frequency may be reflective of the distinct microenvironments; the epithelial cells lining an endometriotic cyst within the ovary are exposed to a highly oxidative environment that promotes tumorigenesis. Understanding the distinct mutation patterns found in the PI3K and Wnt pathways of ovarian and endometrial endometrioid carcinomas may provide future opportunities for stratifying patients for targeted therapeutics.

Exercise-induced mitochondrial p53 repairs mtDNA mutations in mutator mice.

PubMed

Safdar, Adeel; Khrapko, Konstantin; Flynn, James M; Saleem, Ayesha; De Lisio, Michael; Johnston, Adam P W; Kratysberg, Yevgenya; Samjoo, Imtiaz A; Kitaoka, Yu; Ogborn, Daniel I; Little, Jonathan P; Raha, Sandeep; Parise, Gianni; Akhtar, Mahmood; Hettinga, Bart P; Rowe, Glenn C; Arany, Zoltan; Prolla, Tomas A; Tarnopolsky, Mark A

2016-01-01

Human genetic disorders and transgenic mouse models have shown that mitochondrial DNA (mtDNA) mutations and telomere dysfunction instigate the aging process. Epidemiologically, exercise is associated with greater life expectancy and reduced risk of chronic diseases. While the beneficial effects of exercise are well established, the molecular mechanisms instigating these observations remain unclear. Endurance exercise reduces mtDNA mutation burden, alleviates multisystem pathology, and increases lifespan of the mutator mice, with proofreading deficient mitochondrial polymerase gamma (POLG1). We report evidence for a POLG1-independent mtDNA repair pathway mediated by exercise, a surprising notion as POLG1 is canonically considered to be the sole mtDNA repair enzyme. Here, we show that the tumor suppressor protein p53 translocates to mitochondria and facilitates mtDNA mutation repair and mitochondrial biogenesis in response to endurance exercise. Indeed, in mutator mice with muscle-specific deletion of p53, exercise failed to prevent mtDNA mutations, induce mitochondrial biogenesis, preserve mitochondrial morphology, reverse sarcopenia, or mitigate premature mortality. Our data establish a new role for p53 in exercise-mediated maintenance of the mtDNA genome and present mitochondrially targeted p53 as a novel therapeutic modality for diseases of mitochondrial etiology.

Nutlin‐3a selects for cells harbouring TP 53 mutations

PubMed Central

Hollstein, Monica; Arlt, Volker M.; Phillips, David H.

2016-01-01

TP53 mutations occur in half of all human tumours. Mutagen‐induced or spontaneous TP53 mutagenesis can be studied in vitro using the human TP53 knock‐in (Hupki) mouse embryo fibroblast (HUF) immortalisation assay (HIMA). TP53 mutations arise in up to 30% of mutagen‐treated, immortalised HUFs; however, mutants are not identified until TP53 sequence analysis following immortalisation (2–5 months) and much effort is expended maintaining TP53‐WT cultures. In order to improve the selectivity of the HIMA for HUFs harbouring TP53 mutations, we explored the use of Nutlin‐3a, an MDM2 inhibitor that leads to stabilisation and activation of wild‐type (WT) p53. First, we treated previously established immortal HUF lines carrying WT or mutated TP53 with Nutlin‐3a to examine the effect on cell growth and p53 activation. Nutlin‐3a induced the p53 pathway in TP53‐WT HUFs and inhibited cell growth, whereas most TP53‐mutated HUFs were resistant to Nutlin‐3a. We then assessed whether Nutlin‐3a treatment could discriminate between TP53‐WT and TP53‐mutated cells during the HIMA (n = 72 cultures). As immortal clones emerged from senescent cultures, each was treated with 10 µM Nutlin‐3a for 5 days and observed for sensitivity or resistance. TP53 was subsequently sequenced from all immortalised clones. We found that all Nutlin‐3a‐resistant clones harboured TP53 mutations, which were diverse in position and functional impact, while all but one of the Nutlin‐3a‐sensitive clones were TP53‐WT. These data suggest that including a Nutlin‐3a counter‐screen significantly improves the specificity and efficiency of the HIMA, whereby TP53‐mutated clones are selected prior to sequencing and TP53‐WT clones can be discarded. PMID:27813088

Germ line p53 mutations in a familial syndrome of breast cancer, sarcomas, and other neoplasms.

PubMed

Malkin, D; Li, F P; Strong, L C; Fraumeni, J F; Nelson, C E; Kim, D H; Kassel, J; Gryka, M A; Bischoff, F Z; Tainsky, M A

1990-11-30

Familial cancer syndromes have helped to define the role of tumor suppressor genes in the development of cancer. The dominantly inherited Li-Fraumeni syndrome (LFS) is of particular interest because of the diversity of childhood and adult tumors that occur in affected individuals. The rarity and high mortality of LFS precluded formal linkage analysis. The alternative approach was to select the most plausible candidate gene. The tumor suppressor gene, p53, was studied because of previous indications that this gene is inactivated in the sporadic (nonfamilial) forms of most cancers that are associated with LFS. Germ line p53 mutations have been detected in all five LFS families analyzed. These mutations do not produce amounts of mutant p53 protein expected to exert a trans-dominant loss of function effect on wild-type p53 protein. The frequency of germ line p53 mutations can now be examined in additional families with LFS, and in other cancer patients and families with clinical features that might be attributed to the mutation.

Low expression levels of ATM may substitute for CHEK2 /TP53 mutations predicting resistance towards anthracycline and mitomycin chemotherapy in breast cancer

PubMed Central

2012-01-01

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

Gene mutations and increased levels of p53 protein in human squamous cell carcinomas and their cell lines.

PubMed Central

Burns, J. E.; Baird, M. C.; Clark, L. J.; Burns, P. A.; Edington, K.; Chapman, C.; Mitchell, R.; Robertson, G.; Soutar, D.; Parkinson, E. K.

1993-01-01

Using immunocytochemical and Western blotting techniques we have demonstrated the presence of abnormally high levels of p53 protein in 8/24 (33%) of human squamous cell carcinomas (SCC) and 9/18 (50%) of SCC cell lines. There was a correlation between the immunocytochemical results obtained with eight SCC samples and their corresponding cell lines. Direct sequencing of PCR-amplified, reverse transcribed, p53 mRNA confirmed the expression of point mutations in six of the positive cell lines and detected in-frame deletions in two others. We also detected two stop mutations and three out-of-frame deletions in five lines which did not express elevated levels of p53 protein. Several of the mutations found in SCC of the tongue (3/7) were in a region (codons 144-166) previously identified as being a p53 mutational hot spot in non-small cell lung tumours (Mitsudomi et al., 1992). In 11/13 cases only the mutant alleles were expressed suggesting loss or reduced expression of the wild type alleles in these cases. Six of the mutations were also detected in the SCCs from which the lines were derived, strongly suggesting that the mutations occurred, and were selected, in vivo. The 12th mutation GTG-->GGG (valine-->glycine) at codon 216 was expressed in line SCC-12 clone B along with an apparently normal p53 allele and is to our knowledge a novel mutation. Line BICR-19 also expressed a normal p53 allele in addition to one where exon 10 was deleted. Additionally 15 of the SCC lines (including all of those which did not show elevated p53 protein levels) were screened for the presence of human papillomavirus types 16 and 18 and were found to be negative. These results are discussed in relation to the pathogenesis of SCC and the immortalisation of human keratinocytes in vitro. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:8390283

Frequent mutations in the p53 tumor suppressor gene in human leukemia T-cell lines.

PubMed Central

Cheng, J; Haas, M

1990-01-01

Human T-cell leukemia and T-cell acute lymphoblastic leukemia cell lines were studied for alterations in the p53 tumor suppressor gene. Southern blot analysis of 10 leukemic T-cell lines revealed no gross genomic deletions or rearrangements. Reverse transcription-polymerase chain reaction analysis of p53 mRNA indicated that all 10 lines produced p53 mRNA of normal size. By direct sequencing of polymerase chain reaction-amplified cDNA, we detected 11 missense and nonsense point mutations in 5 of the 10 leukemic T-cell lines studied. The mutations are primarily located in the evolutionarily highly conserved regions of the p53 gene. One of the five cell lines in which a mutation was detected possesses a homozygous point mutation in both p53 alleles, while the other four cell lines harbor from two to four different point mutations. An allelic study of two of the lines (CEM, A3/Kawa) shows that the two missense mutations found in each line are located on separate alleles, thus both alleles of the p53 gene may have been functionally inactivated by two different point mutations. Since cultured leukemic T-cell lines represent a late, fully tumorigenic stage of leukemic T cells, mutation of both (or more) alleles of the p53 gene may reflect the selection of cells possessing an increasingly tumorigenic phenotype, whether the selection took place in vivo or in vitro. Previously, we have shown that the HSB-2 T-cell acute lymphoblastic leukemia cell line had lost both alleles of the retinoblastoma tumor suppressor gene. Taken together, our data show that at least 6 of 10 leukemic T-cell lines examined may have lost the normal function of a known tumor suppressor gene, suggesting that this class of genes serves a critical role in the generation of fully tumorigenic leukemic T cells. Images PMID:2144611

Human pluripotent stem cells recurrently acquire and expand dominant negative P53 mutations

PubMed Central

Kamitaki, Nolan; Mitchell, Jana; Avior, Yishai; Mello, Curtis; Kashin, Seva; Mekhoubad, Shila; Ilic, Dusko; Charlton, Maura; Saphier, Genevieve; Handsaker, Robert E.; Genovese, Giulio; Bar, Shiran; Benvenisty, Nissim; McCarroll, Steven A.; Eggan, Kevin

2017-01-01

Human pluripotent stem cells (hPSCs) can self-renew indefinitely, making them an attractive source for regenerative therapies. This expansion potential has been linked with acquisition of large copy number variants (CNVs) that provide mutant cells with a growth advantage in culture1–3. However, the nature, extent, and functional impact of other acquired genome sequence mutations in cultured hPSCs is not known. Here, we sequenced the protein-coding genes (exomes) of 140 independent human embryonic stem cell (hESC) lines, including 26 lines prepared for potential clinical use4. We then applied computational strategies for identifying mutations present in a subset of cells5. Though such mosaic mutations were generally rare, we identified five unrelated hESC lines that carried six mutations in the TP53 gene that encodes the tumor suppressor P53. Notably, the TP53 mutations we observed are dominant negative and are the mutations most commonly seen in human cancers. We used droplet digital PCR to demonstrate that the TP53 mutant allelic fraction increased with passage number under standard culture conditions, suggesting that P53 mutation confers selective advantage. When we then mined published RNA sequencing data from 117 hPSC lines, we observed another nine TP53 mutations, all resulting in coding changes in the DNA binding domain of P53. Strikingly, in three lines, the allelic fraction exceeded 50%, suggesting additional selective advantage resulting from loss of heterozygosity at the TP53 locus. As the acquisition and favored expansion of cancer-associated mutations in hPSCs may go unnoticed during most applications, we suggest that careful genetic characterization of hPSCs and their differentiated derivatives should be carried out prior to clinical use. PMID:28445466

A mutant p53/let-7i-axis-regulated gene network drives cell migration, invasion and metastasis

PubMed Central

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

2015-01-01

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

Construction and Characterization of Human Mammary Epithelial Cell Lines Containing Mutations in the p53 or BRCA1 Genes

DTIC Science & Technology

1999-01-01

development of breast cancers. To study the effects of inactivating mutations in these tumor suppressor genes early in the breast-cancer pathway, we have...the effects of inactivating mutations in these tumor suppressor genes early in the breast-cancer pathway. The consequences of transduction of these...proposed three approaches for constructing p53-deficient cells; i.e., by mutating the p53 gene directly, by abrogating the protein’s normal cellular

Regulation of MDM2 Activity by Nucleolin

DTIC Science & Technology

2005-06-01

tumorigenesis with -50% of human cancers showing mutation of the TP53 gene , often a loss of one gene copy and a point mutation within the second. p53...Sordat B, Gillet M, Schorderet D, Bosman FT, Chaubert P (2001) Methylation silencing and mutations of the p14ARF and pl6INK4a genes in colon cancer. Lab...for the first machinery (for example, see reference 53 and references step of pre-rRNA processing (22). Mutation of the genes en- therein). It is

A mutation spectrum that includes GNAS, KRAS and TP53 may be shared by mucinous neoplasms of the appendix.

PubMed

Hara, Kieko; Saito, Tsuyoshi; Hayashi, Takuo; Yimit, Alkam; Takahashi, Michiko; Mitani, Keiko; Takahashi, Makoto; Yao, Takashi

2015-09-01

Appendiceal mucinous tumors (AMTs) are classified as low-grade appendiceal mucinous neoplasms (LAMNs) or mucinous adenocarcinomas (MACs), although their carcinogenesis is not well understood. As somatic activating mutations of GNAS are considered to be characteristic of LAMNs while TP53 mutations have been shown to be specific to MACs, MACs are unlikely to result from transformation of LAMNs. However, emerging evidence also shows the presence of GNAS mutations in MACs. We examined 16 AMTs (11 LAMNs and 5 MACs) for genetic alterations of GNAS, KRAS, BRAF, TP53, CTNNB1, and TERT promoter in order to elucidate the possibility of a shared genetic background in the two tumor types. Extensive histological examination revealed the presence of a low-grade component in all cases of MAC. GNAS mutations were detected in two LAMNs and in one MAC, although the GNAS mutation in this MAC was a nonsense mutation (Q227X) expected not to be activating mutation. TP53 mutations were detected in three LAMNs; they were frequently detected in MACs. KRAS mutations were detected in three LAMNs and three MACs, and CTNNB1 mutations were detected in two LAMNs. KRAS mutation and activating mutation of GNAS occurred exclusively in AMTs. BRAF and TERT mutations were not detected. Overexpression of p53 was observed in only two MACs, and p53 immunostaining clearly discriminated the high-grade lesion from a low-grade component in one. These findings suggest that p53 overexpression plays an important role in the carcinogenesis of AMTs and that, in addition to mutations of GNAS, KRAS and TP53 alterations might be shared by AMTs, thus providing evidence for the possible progression of LAMNs to MAC. Copyright © 2015 Elsevier GmbH. All rights reserved.

MiR-142-3p is downregulated in aggressive p53 mutant mouse models of pancreatic ductal adenocarcinoma by hypermethylation of its locus.

PubMed

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

2018-05-29

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

Novel p53 tumour suppressor mutations in cases of spindle cell sarcoma, pleomorphic sarcoma and fibrosarcoma in cats.

PubMed

Mayr, B; Reifinger, M; Alton, K; Schaffner, G

1998-06-01

Twenty feline neoplasms were sequenced in the region from exons 5 to 8 for the presence of tumour suppressor gene p53 mutations. In a spindle cell sarcoma of the bladder, a missense mutation (codon 164 AAG-->GAG, lysine-->glutamic acid) in exon 5 was detected. In a pleomorphic sarcoma, a 23 bp deletion involving the splicing junction between intron 5 and exon 6 was observed. In a fibrosarcoma, a 6 bp deletion of p53 covering 2 bp of exon 7 and 4 bp of intron 7, including the splicing junction, was found. The study demonstrates three new p53 mutations in different types of sarcomas in cats.

Genetic Alterations in Colorectal Cancer Have Different Patterns on 18F-FDG PET/CT.

PubMed

Chen, Shang-Wen; Lin, Chien-Yu; Ho, Cheng-Man; Chang, Ya-Sian; Yang, Shu-Fen; Kao, Chia-Hung; Chang, Jan-Gowth

2015-08-01

The aim of this study was to understand the association between various genetic mutation and (18)F-FDG PET-related parameters in patients with colorectal cancer (CRC). One hundred three CRC patients who had undergone preoperative PET/CTs were included in this study. Several PET/CT-related parameters, including SUV(max), and various thresholds of metabolic tumor volume, total lesion glycolysis, and PET/CT-based tumor width (TW) were measured. Using high-resolution melting methods for genetic mutation analysis, tumor- and PET/CT-related parameters were correlated with various genetic alterations including TP53, KRAS, APC, BRAF, and PIK3CA. Mann-Whitney U test and logistic regression analysis were carried out for this analysis. Genetic alterations in TP53, KRAS, and APC were found in 41 (40%), 34 (33%), and 27 (26%) of tumors, respectively. PIK3CA and BRAF were exhibited by 5 and 4 of the patients with CRC. TP53 mutants exhibited higher SUV(max). The odds ratio was 1.28 (P = 0.04; 95% confidence interval, 1.01-1.61). Tumors with a mutated KRAS had an increased accumulation of FDG using a 40% threshold level for maximal uptake of TW (TW(40%)), whereas the odds ratio was 1.15 (P = 0.001; 95% confidence interval, 1.06-1.24). The accuracy of SUV(max) greater than 10 in predicting TP53 mutation was 60%, whereas that for TW(40%) for KRAS was 61%. Increased SUV(max) and TW(40%) were associated in CRC tumors with TP53 and KRAS mutations, respectively. Further studies are required because of the low predictive accuracy.

Base damage, local sequence context and TP53 mutation hotspots: a molecular dynamics study of benzo[a]pyrene induced DNA distortion and mutability

PubMed Central

Menzies, Georgina E.; Reed, Simon H.; Brancale, Andrea; Lewis, Paul D.

2015-01-01

The mutational pattern for the TP53 tumour suppressor gene in lung tumours differs to other cancer types by having a higher frequency of G:C>T:A transversions. The aetiology of this differing mutation pattern is still unknown. Benzo[a]pyrene,diol epoxide (BPDE) is a potent cigarette smoke carcinogen that forms guanine adducts at TP53 CpG mutation hotspot sites including codons 157, 158, 245, 248 and 273. We performed molecular modelling of BPDE-adducted TP53 duplex sequences to determine the degree of local distortion caused by adducts which could influence the ability of nucleotide excision repair. We show that BPDE adducted codon 157 has greater structural distortion than other TP53 G:C>T:A hotspot sites and that sequence context more distal to adjacent bases must influence local distortion. Using TP53 trinucleotide mutation signatures for lung cancer in smokers and non-smokers we further show that codons 157 and 273 have the highest mutation probability in smokers. Combining this information with adduct structural data we predict that G:C>T:A mutations at codon 157 in lung tumours of smokers are predominantly caused by BPDE. Our results provide insight into how different DNA sequence contexts show variability in DNA distortion at mutagen adduct sites that could compromise DNA repair at well characterized cancer related mutation hotspots. PMID:26400171

Cutaneous squamous and neuroendocrine carcinoma: genetically and immunohistochemically different from Merkel cell carcinoma

PubMed Central

Pulitzer, Melissa P; Brannon, A Rose; Berger, Michael F; Louis, Peter; Scott, Sasinya N; Jungbluth, Achim A; Coit, Daniel G; Brownell, Isaac; Busam, Klaus J

2016-01-01

Cutaneous neuroendocrine (Merkel cell) carcinoma most often arises de novo in the background of a clonally integrated virus, the Merkel cell polyomavirus, and is notable for positive expression of retinoblastoma 1 (RB1) protein and low expression of p53 compared with the rare Merkel cell polyomavirus-negative Merkel cell carcinomas. Combined squamous and Merkel cell tumors are consistently negative for Merkel cell polyomavirus. Little is known about their immunophenotypic or molecular profile. Herein, we studied 10 combined cutaneous squamous cell and neuroendocrine carcinomas for immunohistochemical expression of p53, retinoblastoma 1 protein, neurofilament, p63, and cytokeratin 20 (CK20). We compared mutation profiles of five combined Merkel cell carcinomas and seven ‘pure’ Merkel cell carcinomas using targeted next-generation sequencing. Combined tumors were from the head, trunk, and leg of Caucasian males and one female aged 52–89. All cases were highly p53- and p63-positive and neurofilament-negative in the squamous component, whereas RB1-negative in both components. Eight out of 10 were p53-positive, 3/10 p63-positive, and 3/10 focally neurofilament-positive in the neuroendocrine component. Six out of 10 were CK20-positive in any part. By next-generation sequencing, combined tumors were highly mutated, with an average of 48 mutations per megabase compared with pure tumors, which showed 1.25 mutations per megabase. RB1 and p53 mutations were identified in all five combined tumors. Combined tumors represent an immunophenotypically and genetically distinct variant of primary cutaneous neuroendocrine carcinomas, notable for a highly mutated genetic profile, significant p53 expression and/or mutation, absent RB1 expression in the context of increased RB1 mutation, and minimal neurofilament expression. PMID:26022453

Cutaneous squamous and neuroendocrine carcinoma: genetically and immunohistochemically different from Merkel cell carcinoma.

PubMed

Pulitzer, Melissa P; Brannon, A Rose; Berger, Michael F; Louis, Peter; Scott, Sasinya N; Jungbluth, Achim A; Coit, Daniel G; Brownell, Isaac; Busam, Klaus J

2015-08-01

Cutaneous neuroendocrine (Merkel cell) carcinoma most often arises de novo in the background of a clonally integrated virus, the Merkel cell polyomavirus, and is notable for positive expression of retinoblastoma 1 (RB1) protein and low expression of p53 compared with the rare Merkel cell polyomavirus-negative Merkel cell carcinomas. Combined squamous and Merkel cell tumors are consistently negative for Merkel cell polyomavirus. Little is known about their immunophenotypic or molecular profile. Herein, we studied 10 combined cutaneous squamous cell and neuroendocrine carcinomas for immunohistochemical expression of p53, retinoblastoma 1 protein, neurofilament, p63, and cytokeratin 20 (CK20). We compared mutation profiles of five combined Merkel cell carcinomas and seven 'pure' Merkel cell carcinomas using targeted next-generation sequencing. Combined tumors were from the head, trunk, and leg of Caucasian males and one female aged 52-89. All cases were highly p53- and p63-positive and neurofilament-negative in the squamous component, whereas RB1-negative in both components. Eight out of 10 were p53-positive, 3/10 p63-positive, and 3/10 focally neurofilament-positive in the neuroendocrine component. Six out of 10 were CK20-positive in any part. By next-generation sequencing, combined tumors were highly mutated, with an average of 48 mutations per megabase compared with pure tumors, which showed 1.25 mutations per megabase. RB1 and p53 mutations were identified in all five combined tumors. Combined tumors represent an immunophenotypically and genetically distinct variant of primary cutaneous neuroendocrine carcinomas, notable for a highly mutated genetic profile, significant p53 expression and/or mutation, absent RB1 expression in the context of increased RB1 mutation, and minimal neurofilament expression.

Immunohistochemical Analysis of p53, Ki-67, CD44, HER-2/neu Expression Patterns in Gastric Cancer, and Their Association with One Year Survival in North-West of Iran

PubMed Central

Sanaat, Zohreh; Halimi, Monireh; Ghojezadeh, Morteza; Pirovi, Amir Hossein; Gharamaleki, Jalil Vaez; Ziae, Ali Esfahani Jamal Eivazi; Kermani, Iraj Aswadi

2013-01-01

Introduction Gastric cancer remains the second most common cause of cancer-related deaths worldwide. In many malignancies like, lung and breast, multiple prognostic factors are known, such as mutations in Ki-67, HER-2/neu, p53. In this study, we evaluated immunohistochemical protein expression patterns of cell-cycle-regulators p53, proliferation marker Ki-67, surface expression of CD44, HER-2/neu oncogene proposed as useful prognostic factors. Methods In this descriptive-analytic study, we evaluate 100 patients with gastric cancer who were referred to Shahid Ghazi Hospital or other oncology clinics of Tabriz University of Medical Sciences in 2005-2010. Patients with pathologic confirmation of gastric cancer were selected. Expression of p53, ki-67, CD-44, HER-2/neu were detected by immunohistochemical staining. Results In this study, 100 patients with gastric cancer participated. 76(76%) were men and 24(24%) were women with mean age of 64.02(8.05) years. Seventy two samples were intestinal type and 28 were diffuse type. CD44 was positive in 27(27%) patients. P53 was positive in 35(35%) patients. Ki-67 was positive in 53(53%) patients. HER-2/neu was positive in 51(51%) patients. Conclusion The frequency of positive p53, Ki-67, CD44 and HER-2/neu varied in different studies. Positive Ki-67 and HER-2/neu were not associated with changes in survival but positive p53 and CD44 were significantly associated with improved survival. PMID:24505530

p53 inactivation in chewing tobacco-induced oral cancers and leukoplakias from India.

PubMed

Saranath, D; Tandle, A T; Teni, T R; Dedhia, P M; Borges, A M; Parikh, D; Sanghavi, V; Mehta, A R

1999-05-01

The inactivation of p53 tumour suppressor gene vis-á-vis point mutation, overexpression and degradation due to Human Papilloma virus (HPV) 16/18 infection, was examined in chewing tobacco-associated oral cancers and oral leukoplakias from India. The analysis of mutations was assessed by polymerase chain reaction (PCR) with single strand conformation polymorphism (PCR-SSCP) of exons 5-9 on DNA from 83 oral cancer cases, and the mutations confirmed by direct nucleotide sequencing of the PCR products. p53 protein expression was evaluated by immunohistochemical analysis on paraffin-embedded sections of 62 representative oral cancer biopsies and 22 leukoplakias, using p53-specific monoclonal antibody DO-7. The presence of HPV16/18 was detected in the 83 oral cancer cases by PCR analysis using HPV L1 consensus sequences, followed by Southern hybridization with type-specific oligonucleotide probes. Forty-six per cent (38/83) of oral cancer tumours showed p53 alterations, with 17% (14/83) showing point mutations, 37% (23/62) with overexpression and 25% (21/83) with presence of HPV16 wherein the E6 HPV16 protein degrades p53. HPV18 was not detected in any of the samples. Ninety-two per cent concordance was observed between missense point mutations and overexpression of p53 protein. A significant correlation was not observed between p53 alterations in oral cancer and clinico-pathological profile of the patients. Twenty-seven per cent (6/22) of oral leukoplakias showed p53 overexpression. The overall p53 alterations in oral cancer tissues and oral lesions are comparable to data from the oral cancers reported in the Western countries with smoking and alcohol-associated oral cancers, and suggest a critical role for p53 gene in a significant proportion of oral cancers from India. The overexpression of p53 protein in leukoplakias may serve as a valuable biomarker for identifying individuals at high risk of transformation to malignant phenotype.

CP-31398 prevents the growth of p53-mutated colorectal cancer cells in vitro and in vivo.

PubMed

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

2015-03-01

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

Expression of C-terminal deleted p53 isoforms in neuroblastoma

PubMed Central

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

2006-01-01

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

p53 Mutagenesis by Benzo[a]pyrene derived Radical Cations

PubMed Central

Sen, Sushmita; Bhojnagarwala, Pratik; Francey, Lauren; Lu, Ding; Jeffrey Field, Trevor M. Penning

2013-01-01

Benzo[a]pyrene (B[a]P), a major human carcinogen in combustion products such as cigarette smoke and diesel exhaust, is metabolically activated into DNA-reactive metabolites via three different enzymatic pathways. The pathways are the anti-(+)-benzo[a]pyrene 7,8-diol 9, 10-epoxide pathway (P450/ epoxide hydrolase catalyzed) (B[a]PDE), the benzo[a]pyrene o-quinone pathway (aldo ketose reductase (AKR) catalyzed) and the B[a]P radical cation pathway (P450 peroxidase catalyzed). We used a yeast p53 mutagenesis system to assess mutagenesis by B[a]P radical cations. Because radical cations are short-lived, they were generated in situ by reacting B[a]P with cumene hydroperoxide (CuOOH) and horse radish peroxidase (HRP) and then monitoring the generation of the more stable downstream products, B[a]P-1,6-dione and B[a]P-3,6-dione. Based on the B[a]P-1,6 and 3,6-dione formation, approximately 4µM of radical cation was generated. In the mutagenesis assays, the radical cations produced in situ showed a dose-dependent increase in mutagenicity from 0.25 µM to 10 µM B[a]P with no significant increase seen with further escalation to 50 µM B[a]P. However, mutagenesis was 200-fold less than with the AKR pathway derived B[a]P, 7–8 dione. Mutant p53 plasmids, which yield red colonies, were recovered from the yeast to study the pattern and spectrum of mutations. The mutation pattern observed was G to T (31%) > G to C (29%) > G to A (14%). The frequency of codons mutated by the B[a]P radical cations was essentially random and not enriched at known cancer hotspots. The quinone products of radical cations, B[a]P-1,6-dione and B[a]P-3,6-dione were more mutagenic than the radical cation reactions, but still less mutagenic than AKR derived B[a]P-7,8-dione. We conclude that B[a]P radical cations and their quinone products are weakly mutagenic in this yeast-based system compared to redox cycling PAH o-quinones. PMID:22768918

Poor prognosis in non-villous splenic marginal zone cell lymphoma is associated with p53 mutations.

PubMed

Baldini, L; Guffanti, A; Cro, L; Fracchiolla, N S; Colombi, M; Motta, M; Maiolo, A T; Neri, A

1997-11-01

We have recently reported a series of 15 non-villous splenic marginal zone lymphoma patients, six of whom showed p53 mutations (40%). This molecular alteration did not correlate with any particular clinico-pathologic feature at diagnosis. After a median follow-up of 56 months, four cases evolved into aggressive fatal non-Hodgkin's lymphoma (NHL) and two had refractory progressive disease; interestingly, p53 mutations were demonstrated in five of these patients at diagnosis. As the patients with wild-type p53 presented responsive or indolent disease, this genetic alteration may be an early marker of aggressive transformation or refractoriness. p53 evaluation at diagnosis could be advisable in this particular subset of NHL.

Ensemble-Based Computational Approach Discriminates Functional Activity of p53 Cancer and Rescue Mutants

PubMed Central

Demir, Özlem; Baronio, Roberta; Salehi, Faezeh; Wassman, Christopher D.; Hall, Linda; Hatfield, G. Wesley; Chamberlin, Richard; Kaiser, Peter; Lathrop, Richard H.; Amaro, Rommie E.

2011-01-01

The tumor suppressor protein p53 can lose its function upon single-point missense mutations in the core DNA-binding domain (“cancer mutants”). Activity can be restored by second-site suppressor mutations (“rescue mutants”). This paper relates the functional activity of p53 cancer and rescue mutants to their overall molecular dynamics (MD), without focusing on local structural details. A novel global measure of protein flexibility for the p53 core DNA-binding domain, the number of clusters at a certain RMSD cutoff, was computed by clustering over 0.7 µs of explicitly solvated all-atom MD simulations. For wild-type p53 and a sample of p53 cancer or rescue mutants, the number of clusters was a good predictor of in vivo p53 functional activity in cell-based assays. This number-of-clusters (NOC) metric was strongly correlated (r2 = 0.77) with reported values of experimentally measured ΔΔG protein thermodynamic stability. Interpreting the number of clusters as a measure of protein flexibility: (i) p53 cancer mutants were more flexible than wild-type protein, (ii) second-site rescue mutations decreased the flexibility of cancer mutants, and (iii) negative controls of non-rescue second-site mutants did not. This new method reflects the overall stability of the p53 core domain and can discriminate which second-site mutations restore activity to p53 cancer mutants. PMID:22028641

Lung tumors with distinct p53 mutations respond similarly to p53 targeted therapy but exhibit genotype-specific statin sensitivity

PubMed Central

Turrell, Frances K.; Kerr, Emma M.; Gao, Meiling; Thorpe, Hannah; Doherty, Gary J.; Cridge, Jake; Shorthouse, David; Speed, Alyson; Samarajiwa, Shamith; Hall, Benjamin A.; Griffiths, Meryl; Martins, Carla P.

2017-01-01

Lung adenocarcinoma accounts for ∼40% of lung cancers, the leading cause of cancer-related death worldwide, and current therapies provide only limited survival benefit. Approximately half of lung adenocarcinomas harbor mutations in TP53 (p53), making these mutants appealing targets for lung cancer therapy. As mutant p53 remains untargetable, mutant p53-dependent phenotypes represent alternative targeting opportunities, but the prevalence and therapeutic relevance of such effects (gain of function and dominant-negative activity) in lung adenocarcinoma are unclear. Through transcriptional and functional analysis of murine KrasG12D-p53null, -p53R172H (conformational), and -p53R270H (contact) mutant lung tumors, we identified genotype-independent and genotype-dependent therapeutic sensitivities. Unexpectedly, we found that wild-type p53 exerts a dominant tumor-suppressive effect on mutant tumors, as all genotypes were similarly sensitive to its restoration in vivo. These data show that the potential of p53 targeted therapies is comparable across all p53-deficient genotypes and may explain the high incidence of p53 loss of heterozygosity in mutant tumors. In contrast, mutant p53 gain of function and their associated vulnerabilities can vary according to mutation type. Notably, we identified a p53R270H-specific sensitivity to simvastatin in lung tumors, and the transcriptional signature that underlies this sensitivity was also present in human lung tumors, indicating that this therapeutic approach may be clinically relevant. PMID:28790158

Using an International p53 Mutation Database as a Foundation for an Online Laboratory in an Upper Level Undergraduate Biology Class

ERIC Educational Resources Information Center

Melloy, Patricia G.

2015-01-01

A two-part laboratory exercise was developed to enhance classroom instruction on the significance of p53 mutations in cancer development. Students were asked to mine key information from an international database of p53 genetic changes related to cancer, the IARC TP53 database. Using this database, students designed several data mining activities…

WNT activation by lithium abrogates TP53 mutation associated radiation resistance in medulloblastoma.

PubMed

Zhukova, Nataliya; Ramaswamy, Vijay; Remke, Marc; Martin, Dianna C; Castelo-Branco, Pedro; Zhang, Cindy H; Fraser, Michael; Tse, Ken; Poon, Raymond; Shih, David J H; Baskin, Berivan; Ray, Peter N; Bouffet, Eric; Dirks, Peter; von Bueren, Andre O; Pfaff, Elke; Korshunov, Andrey; Jones, David T W; Northcott, Paul A; Kool, Marcel; Pugh, Trevor J; Pomeroy, Scott L; Cho, Yoon-Jae; Pietsch, Torsten; Gessi, Marco; Rutkowski, Stefan; Bognár, Laszlo; Cho, Byung-Kyu; Eberhart, Charles G; Conter, Cecile Faure; Fouladi, Maryam; French, Pim J; Grajkowska, Wieslawa A; Gupta, Nalin; Hauser, Peter; Jabado, Nada; Vasiljevic, Alexandre; Jung, Shin; Kim, Seung-Ki; Klekner, Almos; Kumabe, Toshihiro; Lach, Boleslaw; Leonard, Jeffrey R; Liau, Linda M; Massimi, Luca; Pollack, Ian F; Ra, Young Shin; Rubin, Joshua B; Van Meir, Erwin G; Wang, Kyu-Chang; Weiss, William A; Zitterbart, Karel; Bristow, Robert G; Alman, Benjamin; Hawkins, Cynthia E; Malkin, David; Clifford, Steven C; Pfister, Stefan M; Taylor, Michael D; Tabori, Uri

2014-12-24

TP53 mutations confer subgroup specific poor survival for children with medulloblastoma. We hypothesized that WNT activation which is associated with improved survival for such children abrogates TP53 related radioresistance and can be used to sensitize TP53 mutant tumors for radiation. We examined the subgroup-specific role of TP53 mutations in a cohort of 314 patients treated with radiation. TP53 wild-type or mutant human medulloblastoma cell-lines and normal neural stem cells were used to test radioresistance of TP53 mutations and the radiosensitizing effect of WNT activation on tumors and the developing brain. Children with WNT/TP53 mutant medulloblastoma had higher 5-year survival than those with SHH/TP53 mutant tumours (100% and 36.6%±8.7%, respectively (p<0.001)). Introduction of TP53 mutation into medulloblastoma cells induced radioresistance (survival fractions at 2Gy (SF2) of 89%±2% vs. 57.4%±1.8% (p<0.01)). In contrast, β-catenin mutation sensitized TP53 mutant cells to radiation (p<0.05). Lithium, an activator of the WNT pathway, sensitized TP53 mutant medulloblastoma to radiation (SF2 of 43.5%±1.5% in lithium treated cells vs. 56.6±3% (p<0.01)) accompanied by increased number of γH2AX foci. Normal neural stem cells were protected from lithium induced radiation damage (SF2 of 33%±8% for lithium treated cells vs. 27%±3% for untreated controls (p=0.05). Poor survival of patients with TP53 mutant medulloblastoma may be related to radiation resistance. Since constitutive activation of the WNT pathway by lithium sensitizes TP53 mutant medulloblastoma cells and protect normal neural stem cells from radiation, this oral drug may represent an attractive novel therapy for high-risk medulloblastomas.

Oncogenic c-Myc-induced lymphomagenesis is inhibited non-redundantly by the p19Arf–Mdm2–p53 and RP–Mdm2–p53 pathways

PubMed Central

Meng, X; Carlson, NR; Dong, J; Zhang, Y

2016-01-01

The multifaceted oncogene c-Myc plays important roles in the development and progression of human cancer. Recent in vitro and in vivo studies have shown that the p19Arf–Mdm2–p53 and the ribosomal protein (RP)–Mdm2–p53 pathways are both essential in preventing oncogenic c-Myc-induced tumorigenesis. Disruption of each pathway individually by p19Arf deletion or by Mdm2C305F mutation, which disrupts RP-Mdm2 binding, accelerates Eμ-myc transgene-induced pre-B/B-cell lymphoma in mice at seemingly similar paces with median survival around 10 and 11 weeks, respectively, compared to 20 weeks for Eμ-myc transgenic mice. Because p19Arf can inhibit ribosomal biogenesis through its interaction with nucleophosmin (NPM/B23), RNA helicase DDX5 and RNA polymerase I transcription termination factor (TTF-I), it has been speculated that the p19Arf–Mdm2–p53 and the RP–Mdm2–p53 pathways might be a single p19Arf–RP–Mdm2–p53 pathway, in which p19Arf activates p53 by inhibiting RP biosynthesis; thus, p19Arf deletion or Mdm2C305F mutation would result in similar consequences. Here, we generated mice with concurrent p19Arf deletion and Mdm2C305F mutation and investigated the compound mice for tumorigenesis in the absence and the presence of oncogenic c-Myc overexpression. In the absence of Eμ-myc transgene, the Mdm2C305F mutation did not elicit spontaneous tumors in mice, nor did it accelerate spontaneous tumors in mice with p19Arf deletion. In the presence of Eμ-myc transgene, however, Mdm2C305F mutation significantly accelerated p19Arf deletion-induced lymphomagenesis and promoted rapid metastasis. We found that when p19Arf–Mdm2–p53 and RP–Mdm2–p53 pathways are independently disrupted, oncogenic c-Myc-induced p53 stabilization and activation is only partially attenuated. When both pathways are concurrently disrupted, however, c-Myc-induced p53 stabilization and activation are essentially obliterated. Thus, the p19Arf–Mdm2–p53 and the RP–Mdm2–p53 are non-redundant pathways possessing similar capabilities to activate p53 upon c-Myc overexpression. PMID:25823025

Wee-1 Kinase Inhibition Overcomes Cisplatin Resistance Associated with High-Risk TP53 Mutations in Head and Neck Cancer through Mitotic Arrest Followed by Senescence

PubMed Central

Osman, Abdullah A.; Monroe, Marcus M.; Ortega Alves, Marcus V.; Patel, Ameeta A.; Katsonis, Panagiotis; Fitzgerald, Alison L.; Neskey, David M.; Frederick, Mitchell J.; Woo, Sang Hyeok; Caulin, Carlos; Hsu, Teng-Kuei; McDonald, Thomas O.; Kimmel, Marek; Meyn, Raymond E.; Lichtarge, Olivier; Myers, Jeffrey N.

2015-01-01

Although cisplatin has played a role in “standard-of-care” multimodality therapy for patients with advanced squamous cell carcinoma of the head and neck (HNSCC), the rate of treatment failure remains particularly high for patients receiving cisplatin whose tumors have mutations in the TP53 gene. We found that cisplatin treatment of HNSCC cells with mutant TP53 leads to arrest of cells in the G2 phase of the cell cycle, leading us to hypothesize that the wee-1 kinase inhibitor MK-1775 would abrogate the cisplatin-induced G2 block and thereby sensitize isogenic HNSCC cells with mutant TP53 or lacking p53 expression to cisplatin. We tested this hypothesis using clonogenic survival assays, flow cytometry, and in vivo tumor growth delay experiments with an orthotopic nude mouse model of oral tongue cancer. We also used a novel TP53 mutation classification scheme to identify which TP53 mutations are associated with limited tumor responses to cisplatin treatment. Clonogenic survival analyses indicate that nanomolar concentration of MK-1775 sensitizes HNSCC cells with high-risk mutant p53 to cisplatin. Consistent with its ability to chemosensitize, MK-1775 abrogated the cisplatin-induced G2 block in p53-defective cells leading to mitotic arrest associated with a senescence-like phenotype. Furthermore, MK-1775 enhanced the efficacy of cisplatin in vivo in tumors harboring TP53 mutations. These results indicate that HNSCC cells expressing high-risk p53 mutations are significantly sensitized to cisplatin therapy by the selective wee-1 kinase inhibitor, supporting the clinical evaluation of MK-1775 in combination with cisplatin for the treatment of patients with TP53 mutant HNSCC. PMID:25504633

ERK mediated upregulation of death receptor 5 overcomes the lack of p53 functionality in the diaminothiazole DAT1 induced apoptosis in colon cancer models: efficiency of DAT1 in Ras-Raf mutated cells.

PubMed

Thamkachy, Reshma; Kumar, Rohith; Rajasekharan, K N; Sengupta, Suparna

2016-03-08

p53 is a tumour suppressor protein that plays a key role in many steps of apoptosis, and malfunctioning of this transcription factor leads to tumorigenesis. Prognosis of many tumours also depends upon the p53 status. Most of the clinically used anticancer compounds activate p53 dependent pathway of apoptosis and hence require p53 for their mechanism of action. Further, Ras/Raf/MEK/ERK axis is an important signaling pathway activated in many cancers. Dependence of diaminothiazoles, compounds that have gained importance recently due to their anticancer and anti angiogenic activities, were tested in cancer models with varying p53 or Ras/Raf mutational status. In this study we have used p53 mutated and knock out colon cancer cells and xenograft tumours to study the role of p53 in apoptosis mediated by diaminothiazoles. Colon cancer cell lines with varying mutational status for Ras or Raf were also used. We have also examined the toxicity and in vivo efficacy of a lead diaminothiazole 4-Amino-5-benzoyl-2-(4-methoxy phenylamino)thiazole (DAT1) in colon cancer xenografts. We have found that DAT1 is active in both in vitro and in vivo models with nonfunctional p53. Earlier studies have shown that extrinsic pathway plays major role in DAT1 mediated apoptosis. In this study, we have found that DAT1 is causing p53 independent upregulation of the death receptor 5 by activating the Ras/Raf/MEK/ERK signaling pathway both in wild type and p53 suppressed colon cancer cells. These findings are also confirmed by the in vivo results. Further, DAT1 is more efficient to induce apoptosis in colon cancer cells with mutated Ras or Raf. Minimal toxicity in both acute and subacute studies along with the in vitro and in vivo efficacy of DAT1 in cancers with both wild type and nonfunctional p53 place it as a highly beneficial candidate for cancer chemotherapy. Besides, efficiency in cancer cells with mutations in the Ras oncoprotein or its downstream kinase Raf raise interest in diaminothiazole class of compounds for further follow-up.

A novel P53/POMC/Gαs/SASH1 autoregulatory feedback loop activates mutated SASH1 to cause pathologic hyperpigmentation.

PubMed

Zhou, Ding'an; Wei, Zhiyun; Kuang, Zhongshu; Luo, Huangchao; Ma, Jiangshu; Zeng, Xing; Wang, Ke; Liu, Beizhong; Gong, Fang; Wang, Jing; Lei, Shanchuan; Wang, Dongsheng; Zeng, Jiawei; Wang, Teng; He, Yong; Yuan, Yongqiang; Dai, Hongying; He, Lin; Xing, Qinghe

2017-04-01

p53-Transcriptional-regulated proteins interact with a large number of other signal transduction pathways in the cell, and a number of positive and negative autoregulatory feedback loops act upon the p53 response. P53 directly controls the POMC/α-MSH productions induced by ultraviolet (UV) and is associated with UV-independent pathological pigmentation. When identifying the causative gene of dyschromatosis universalis hereditaria (DUH), we found three mutations encoding amino acid substitutions in the gene SAM and SH3 domain containing 1 (SASH1), and SASH1 was associated with guanine nucleotide-binding protein subunit-alpha isoforms short (Gαs). However, the pathological gene and pathological mechanism of DUH remain unknown for about 90 years. We demonstrate that SASH1 is physiologically induced by p53 upon UV stimulation and SASH and p53 is reciprocally induced at physiological and pathophysiological conditions. SASH1 is regulated by a novel p53/POMC/α-MSH/Gαs/SASH1 cascade to mediate melanogenesis. A novel p53/POMC/Gαs/SASH1 autoregulatory positive feedback loop is regulated by SASH1 mutations to induce pathological hyperpigmentation phenotype. Our study demonstrates that a novel p53/POMC/Gαs/SASH1 autoregulatory positive feedback loop is regulated by SASH1 mutations to induce pathological hyperpigmentation phenotype. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

KRAS and TP53 mutations in inflammatory bowel disease-associated colorectal cancer: a meta-analysis

PubMed Central

Du, Lijun; Kim, John J.; Shen, Jinhua; Chen, Binrui; Dai, Ning

2017-01-01

Although KRAS and TP53 mutations are common in both inflammatory bowel disease-associated colorectal cancer (IBD-CRC) and sporadic colorectal cancer (S-CRC), molecular events leading to carcinogenesis may be different. Previous studies comparing the frequency of KRAS and TP53 mutations in IBD-CRC and S-CRC were inconsistent. We performed a meta-analysis to compare the presence of KRAS and TP53 mutations among patients with IBD-CRC, S-CRC, and IBD without dysplasia. A total of 19 publications (482 patients with IBD-CRC, 4,222 with S-CRC, 281 with IBD without dysplasia) met the study inclusion criteria. KRAS mutation was less frequent (RR=0.71, 95%CI 0.56-0.90; P=0.004) while TP53 mutation was more common (RR=1.24, 95%CI 1.10-1.39; P<0.001) in patients with IBD-CRC compared to S-CRC. Both KRAS (RR=3.09, 95%CI 1.47-6.51; P=0.003) and TP53 (RR=2.15, 95%CI 1.07-4.31 P=0.03) mutations were more prevalent in patients with IBD-CRC compared to IBD without dysplasia. In conclusion, IBD-CRC and S-CRC appear to have biologically different molecular pathways. TP53 appears to be more important than KRAS in IBD-CRC compared to S-CRC. Our findings suggest possible roles of TP53 and KRAS as biomarkers for cancer and dysplasia screening among patients with IBD and may also provide targeted therapy in patients with IBD-CRC. PMID:28077799

Clinicopathogenomic analysis of mismatch repair proficient colorectal adenocarcinoma uncovers novel prognostic subgroups with differing patterns of genetic evolution.

PubMed

Braxton, David R; Zhang, Ray; Morrissette, Jennifer D; Loaiza-Bonilla, Arturo; Furth, Emma E

2016-10-01

Cancer somatic genetic evolution is a direct contributor to heterogeneity at the clonal and molecular level in colorectal adenocarcinoma (COAD). We sought to determine the extent to which genetic evolution may be detected in COAD in routinely obtained single clinical specimens and establish clinical significance with regard to clinicopathologic and outcome data. One hundred and twenty three cases of routinely collected mismatch repair proficient COAD were sequenced on the Illumina Truseq Amplicon assay. Measures of intratumoral heterogeneity and the preferential timing of mutational events were assessed and compared to clinicopathologic data. Survival subanalysis was performed on 55 patients. Patient age (p = 0.013) and specimen percent tumor (p = 0.033) was associated with clonal diversity, and biopsy (p = 0.044) and metastasis (p = 0.044) returned fewer mutations per case. APC and TP53 mutations preferentially occurred early while alterations in FBXW7, FLT3, SMAD4, GNAS and PTEN preferentially occurred as late events. Temporal heterogeneity was evident in KRAS and PIK3CA mutations. Hierarchical clustering revealed a TP53 mutant subtype and a MAPK-PIK3CA subtype with differing patterns of late mutational events. Survival subanalysis showed a decreased median progression free survival for the MAPK-PIK3CA subtype (8 months vs. 13 months; univariate logrank p = 0.0380, cox model p= 0.018). Neoadjuvant therapy associated mutations were found for ERBB2 (p = 0.0481) and FBXW7 (p = 0.015). Our data indicate novel molecular subtypes of mismatch repair proficient COAD display differing patterns of genetic evolution which correlate with clinical outcomes. Furthermore, we report treatment acquired and/or selected mutations in ERBB2 and FBXW7. © 2016 UICC.

Whole-genome sequencing analysis of phenotypic heterogeneity and anticipation in Li-Fraumeni cancer predisposition syndrome.

PubMed

Ariffin, Hany; Hainaut, Pierre; Puzio-Kuter, Anna; Choong, Soo Sin; Chan, Adelyne Sue Li; Tolkunov, Denis; Rajagopal, Gunaretnam; Kang, Wenfeng; Lim, Leon Li Wen; Krishnan, Shekhar; Chen, Kok-Siong; Achatz, Maria Isabel; Karsa, Mawar; Shamsani, Jannah; Levine, Arnold J; Chan, Chang S

2014-10-28

The Li-Fraumeni syndrome (LFS) and its variant form (LFL) is a familial predisposition to multiple forms of childhood, adolescent, and adult cancers associated with germ-line mutation in the TP53 tumor suppressor gene. Individual disparities in tumor patterns are compounded by acceleration of cancer onset with successive generations. It has been suggested that this apparent anticipation pattern may result from germ-line genomic instability in TP53 mutation carriers, causing increased DNA copy-number variations (CNVs) with successive generations. To address the genetic basis of phenotypic disparities of LFS/LFL, we performed whole-genome sequencing (WGS) of 13 subjects from two generations of an LFS kindred. Neither de novo CNV nor significant difference in total CNV was detected in relation with successive generations or with age at cancer onset. These observations were consistent with an experimental mouse model system showing that trp53 deficiency in the germ line of father or mother did not increase CNV occurrence in the offspring. On the other hand, individual records on 1,771 TP53 mutation carriers from 294 pedigrees were compiled to assess genetic anticipation patterns (International Agency for Research on Cancer TP53 database). No strictly defined anticipation pattern was observed. Rather, in multigeneration families, cancer onset was delayed in older compared with recent generations. These observations support an alternative model for apparent anticipation in which rare variants from noncarrier parents may attenuate constitutive resistance to tumorigenesis in the offspring of TP53 mutation carriers with late cancer onset.

The different faces of the p. A53T alpha-synuclein mutation: A screening of Greek patients with parkinsonism and/or dementia.

PubMed

Breza, Marianthi; Koutsis, Georgios; Karadima, Georgia; Potagas, Constantin; Kartanou, Chrisoula; Papageorgiou, Sokratis G; Paraskevas, George P; Kapaki, Elisabeth; Stefanis, Leonidas; Panas, Marios

2018-04-13

The p. A53T mutation in the alpha-synuclein (SNCA) gene is a rare cause of autosomal dominant Parkinson's disease (PD). Although generally rare, it is particularly common in the Greek population due to a founder effect. A53T-positive PD patients often develop dementia during disease course and may very rarely present with dementia. We screened for the p. A53T SNCA mutation a total of 347 cases of Greek origin with parkinsonism and/or dementia, collected over 15 years at the Neurogenetics Unit, Eginition Hospital, University of Athens. Cases were classified into: "pure parkinsonism", "pure dementia" and "parkinsonism plus dementia". In total, 4 p. A53T SNCA mutation carriers were identified. All had autosomal dominant family history and early onset. Screening of the "pure parkinsonism" category revealed 2 cases with typical PD. The other two mutation carriers were identified in the "parkinsonism plus dementia" category. One had a diagnosis of PD dementia and the other of behavioral variant frontotemporal dementia. Screening of patients with "pure dementia" failed to identify any further A53T-positive cases. Our results confirm that the p. A53T SNCA mutation is relatively common in Greek patients with PD or PD plus dementia, particularly in cases with early onset and/or autosomal dominant family history. Copyright © 2017 Elsevier B.V. All rights reserved.

Age at cancer onset in germline TP53 mutation carriers: association with polymorphisms in predicted G-quadruplex structures

PubMed Central

Hainaut, Pierre

2014-01-01

Germline TP53 mutations predispose to multiple cancers defining Li-Fraumeni/Li-Fraumeni-like syndrome (LFS/LFL), a disease with large individual disparities in cancer profiles and age of onset. G-quadruplexes (G4s) are secondary structural motifs occurring in guanine tracks, with regulatory effects on DNA and RNA. We analyzed 85 polymorphisms within or near five predicted G4s in TP53 in search of modifiers of penetrance of LFS/LFL in Brazilian cancer families with (n = 35) or without (n = 110) TP53 mutations. Statistical analyses stratified on family structure showed that cancer tended to occur ~15 years later in mutation carriers who also carried the variant alleles of two polymorphisms within predicted G4-forming regions, rs17878362 (TP53 PIN3, 16 bp duplication in intron 3; P = 0.082) and rs17880560 (6 bp duplication in 3′ flanking region; P = 0.067). Haplotype analysis showed that this inverse association was driven by the polymorphic status of the remaining wild-type (WT) haplotype in mutation carriers: in carriers with a WT haplotype containing at least one variant allele of rs17878362 or rs17880560, cancer occurred ~15 years later than in carriers with other WT haplotypes (P = 0.019). No effect on age of cancer onset was observed in subjects without a TP53 mutation. The G4 in intron 3 has been shown to regulate alternative p53 messenger RNA splicing, whereas the biological roles of predicted G4s in the 3′ flanking region remain to be elucidated. In conclusion, this study demonstrates that G4 polymorphisms in haplotypes of the WT TP53 allele have an impact on LFS/LFL penetrance in germline TP53 mutation carriers. PMID:24336192

Molecular epidemiology in environmental health: the potential of tumor suppressor gene p53 as a biomarker.

PubMed Central

Semenza, J C; Weasel, L H

1997-01-01

One of the challenges in environmental health is to attribute a certain health effect to a specific environmental exposure and to establish a cause-effect relationship. Molecular epidemiology offers a new approach to addressing these challenges. Mutations in the tumor suppressor gene p53 can shed light on past environmental exposure, and carcinogenic agents and doses can be distinguished on the basis of mutational spectra and frequency. Mutations in p53 have successfully been used to establish links between dietary aflatoxin exposure and liver cancer, exposure to ultraviolet light and skin cancer, smoking and cancers of the lung and bladder, and vinyl chloride exposure and liver cancer. In lung cancer, carcinogens from tobacco smoke have been shown to form adducts with DNA. The location of these adducts correlates with those positions in the p53 gene that are mutated in lung cancer, confirming a direct etiologic link between exposure and disease. Recent investigations have also explored the use of p53 as a susceptibility marker for cancer. Furthermore, studies in genetic toxicology have taken advantage of animals transgenic for p53 to screen for carcinogens in vivo. In this review, we summarize recent developments in p53 biomarker research and illustrate applications to environmental health. PMID:9114284

Variation of p53 mutational spectra between carcinoma of the upper and lower respiratory tract.

PubMed

Law, J C; Whiteside, T L; Gollin, S M; Weissfeld, J; El-Ashmawy, L; Srivastava, S; Landreneau, R J; Johnson, J T; Ferrell, R E

1995-07-01

Mutations of the p53 tumor suppressor gene are the most common genetic alterations associated with human cancer. Tumor-associated p53 mutations often show characteristic tissue-specific profiles which may infer environmentally induced mutational mechanisms. The p53 mutational frequency and spectrum were determined for 95 carcinomas of the upper and lower respiratory tract (32 lung and 63 upper respiratory tract). Mutations were identified at a frequency of 30% in upper respiratory tract (URT) tumors and 31% in lung tumors. All 29 identified mutations were single-base substitutions. Comparison of the frequency of specific base substitutions between lung and URT showed a striking difference. Transitions occurred at a frequency of 68% in URT, but only 30% in lung. Mutations involving G:C-->A:T transitions, which are commonly reported in gastric and esophageal tumors, were the most frequently identified alteration in URT (11/19). Mutations involving G:C-->T:A transversions, which were relatively common in lung tumors (3/10) and are representative of tobacco smoke-induced mutations were rare in URT tumors (1/19). Interestingly, G:C-->A:T mutations at CpG sites, which are characteristic of endogenous processes, were observed frequently in URT tumors (9/19) but only rarely in lung tumors (1/10), suggesting that both endogenous and exogenous factors are responsible for the observed differences in mutational spectra between the upper and lower respiratory systems.

An extensive molecular cytogenetic characterization in high-risk chronic lymphocytic leukemia identifies karyotype aberrations and TP53 disruption as predictors of outcome and chemorefractoriness

PubMed Central

Cavallari, Maurizio; Quaglia, Francesca Maria; Lista, Enrico; Urso, Antonio; Guardalben, Emanuele; Martinelli, Sara; Saccenti, Elena; Bassi, Cristian; Lupini, Laura; Bardi, Maria Antonella; Volta, Eleonora; Tammiso, Elisa; Melandri, Aurora; Negrini, Massimo

2017-01-01

We investigated whether karyotype analysis and mutational screening by next generation sequencing could predict outcome in 101 newly diagnosed chronic lymphocytic leukemia patients with high-risk features, as defined by the presence of unmutated IGHV gene and/or 11q22/17p13 deletion by FISH and/or TP53 mutations. Cytogenetic analysis showed favorable findings (normal karyotype and isolated 13q14 deletion) in 30 patients, unfavorable (complex karyotype and/or 17p13/11q22 deletion) in 34 cases and intermediate (all other abnormalities) in 36 cases. A complex karyotype was present in 21 patients. Mutations were detected in 56 cases and were associated with unmutated IGHV status (p = 0.040) and complex karyotype (p = 0.047). TP53 disruption (i.e. TP53 mutations and/or 17p13 deletion by FISH) correlated with the presence of ≥ 2 mutations (p = 0.001) and a complex karyotype (p = 0.012). By multivariate analysis, an advanced Binet stage (p < 0.001) and an unfavorable karyotype (p = 0.001) predicted a shorter time to first treatment. TP53 disruption (p = 0.019) and the unfavorable karyotype (p = 0.028) predicted a worse overall survival. A shorter time to chemorefractoriness was associated with TP53 disruption (p = 0.001) and unfavorable karyotype (p = 0.025). Patients with both unfavorable karyotype and TP53 disruption presented a dismal outcome (median overall survival and time to chemorefractoriness of 28.7 and 15.0 months, respectively). In conclusion, karyotype analysis refines risk stratification in high-risk CLL patients and could identify a subset of patients with highly unfavorable outcome requiring alternative treatments. PMID:28427204

Reversion of apoptotic resistance of TP53-mutated Burkitt lymphoma B-cells to spindle poisons by exogenous activation of JNK and p38 MAP kinases.

PubMed

Farhat, M; Poissonnier, A; Hamze, A; Ouk-Martin, C; Brion, J-D; Alami, M; Feuillard, J; Jayat-Vignoles, C

2014-05-01

Defects in apoptosis are frequently the cause of cancer emergence, as well as cellular resistance to chemotherapy. These phenotypes may be due to mutations of the tumor suppressor TP53 gene. In this study, we examined the effect of various mitotic spindle poisons, including the new isocombretastatin derivative isoNH2CA-4 (a tubulin-destabilizing molecule, considered to bind to the colchicine site by analogy with combretastatin A-4), on BL (Burkitt lymphoma) cells. We found that resistance to spindle poison-induced apoptosis could be reverted in tumor protein p53 (TP53)-mutated cells by EBV (Epstein Barr virus) infection. This reversion was due to restoration of the intrinsic apoptotic pathway, as assessed by relocation of the pro-apoptotic molecule Bax to mitochondria, loss of mitochondrial integrity and activation of the caspase cascade with PARP (poly ADP ribose polymerase) cleavage. EBV sensitized TP53-mutated BL cells to all spindle poisons tested, including vincristine and taxol, an effect that was systematically downmodulated by pretreatment of cells with inhibitors of p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases. Exogenous activation of p38 and JNK pathways by dihydrosphingosine reverted resistance of TP53-mutated BL cells to spindle poisons. Dihydrosphingosine treatment of TP53-deficient Jurkat and K562 cell lines was also able to induce cell death. We conclude that activation of p38 and JNK pathways may revert resistance of TP53-mutated cells to spindle poisons. This opens new perspectives for developing alternative therapeutic strategies when the TP53 gene is inactivated.

Mutant p53-R273H mediates cancer cell survival and anoikis resistance through AKT-dependent suppression of BCL2-modifying factor (BMF).

PubMed

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

2015-07-16

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

Mixed endometrial carcinomas with a "low-grade serous"-like component: a clinicopathologic, immunohistochemical, and molecular genetic study.

PubMed

Espinosa, Iñigo; D'Angelo, Emanuela; Corominas, Marina; Gonzalez, Alan; Prat, Jaime

2018-01-01

Recently, we reported 2 mixed endometrioid endometrial carcinomas with a "low-grade serous"-like component, which does not fit into any of the 4 molecular groups described by The Cancer Genome Atlas. To understand the nature of these tumors, we have done an immunohistochemical and molecular genetic study of these 2 cases and added a third case. Immunoreactivity for p53, ER, Ki67, WT1, MLH1, PMS2, MSH2, and MSH6 was assessed. Targeted next-generation sequencing for somatic mutations, including genes commonly implicated in carcinogenesis including TP53, KRAS, and PIK3CA, and Sanger sequencing for PTEN and POLE were also performed. All patients were nulliparous and had morbid obesity. Their tumors showed a micropapillary component that resembled that of ovarian low-grade serous carcinoma and merged with villoglandular endometrioid carcinoma. The invasive tumor glands exhibited a microcystic, elongated, or fragmented pattern and contained psammoma bodies. Two tumors showed aberrant p53 expression, and all 3 were positive for ER. All showed KRAS mutations, and TP53 mutations were found in 2 cases. One patient developed peritoneal carcinomatosis, one patient is alive with disease, and another died of a brain tumor. The third patient, whose tumor was confined to the uterus (stage IA), is alive without evidence of disease, but she has been followed for only 6 months. Mixed endometrial carcinomas with a "low-grade" serous-like component exhibit a morphologic spectrum of endometrioid and serous differentiation with microcystic, elongated, or fragmented features; ER expression; KRAS and TP53 mutations; and aggressive behavior. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Mutant p53 Proteins on Glycolysis and Mitochondrial Metabolism.

PubMed

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

2017-12-15

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

The UMD-p53 database: new mutations and analysis tools.

PubMed

Béroud, Christophe; Soussi, Thierry

2003-03-01

The tumor suppressor gene TP53 (p53) is the most extensively studied gene involved in human cancers. More than 1,400 publications have reported mutations of this gene in 150 cancer types for a total of 14,971 mutations. To exploit this huge bulk of data, specific analytic tools were highly warranted. We therefore developed a locus-specific database software called UMD-p53. This database compiles all somatic and germline mutations as well as polymorphisms of the TP53 gene which have been reported in the published literature since 1989, or unpublished data submitted to the database curators. The database is available at www.umd.necker.fr or at http://p53.curie.fr/. In this paper, we describe recent developments of the UMD-p53 database. These developments include new fields and routines. For example, the analysis of putative acceptor or donor splice sites is now automated and gives new insight for the causal role of "silent mutations." Other routines have also been created such as the prescreening module, the UV module, and the cancer distribution module. These new improvements will help users not only for molecular epidemiology and pharmacogenetic studies but also for patient-based studies. To achieve theses purposes we have designed a procedure to check and validate data in order to reach the highest quality data. Copyright 2003 Wiley-Liss, Inc.

Suppression of gain-of-function mutant p53 with metabolic inhibitors reduces tumor growth in vivo

PubMed Central

Jung, Chae Lim; Mun, Hyemin; Jo, Se-Young; Oh, Ju-Hee; Lee, ChuHee; Choi, Eun-Kyung; Jang, Se Jin; Suh, Young-Ah

2016-01-01

Mutation of p53 occasionally results in a gain of function, which promotes tumor growth. We asked whether destabilizing the gain-of-function protein would kill tumor cells. Downregulation of the gene reduced cell proliferation in p53-mutant cells, but not in p53-null cells, indicating that the former depended on the mutant protein for survival. Moreover, phenformin and 2-deoxyglucose suppressed cell growth and simultaneously destabilized mutant p53. The AMPK pathway, MAPK pathway, chaperone proteins and ubiquitination all contributed to this process. Interestingly, phenformin and 2-deoxyglucose also reduced tumor growth in syngeneic mice harboring the p53 mutation. Thus, destabilizing mutant p53 protein in order to kill cells exhibiting “oncogene addiction” could be a promising strategy for combatting p53 mutant tumors. PMID:27765910

Suppression of gain-of-function mutant p53 with metabolic inhibitors reduces tumor growth in vivo.

PubMed

Jung, Chae Lim; Mun, Hyemin; Jo, Se-Young; Oh, Ju-Hee; Lee, ChuHee; Choi, Eun-Kyung; Jang, Se Jin; Suh, Young-Ah

2016-11-22

Mutation of p53 occasionally results in a gain of function, which promotes tumor growth. We asked whether destabilizing the gain-of-function protein would kill tumor cells. Downregulation of the gene reduced cell proliferation in p53-mutant cells, but not in p53-null cells, indicating that the former depended on the mutant protein for survival. Moreover, phenformin and 2-deoxyglucose suppressed cell growth and simultaneously destabilized mutant p53. The AMPK pathway, MAPK pathway, chaperone proteins and ubiquitination all contributed to this process. Interestingly, phenformin and 2-deoxyglucose also reduced tumor growth in syngeneic mice harboring the p53 mutation. Thus, destabilizing mutant p53 protein in order to kill cells exhibiting "oncogene addiction" could be a promising strategy for combatting p53 mutant tumors.

Gene mutation analysis in non-small cell lung cancer patients using bronchoalveolar lavage fluid and tumor tissue as diagnostic markers.

PubMed

Li, Jian; Hu, Yi-Ming; Wang, Yi; Tang, Xing-Ping; Shi, Wei-Lin; Du, Yong-Jie

2014-12-09

Non-small cell lung cancer (NSCLC) is one of the main causes of cancer death in the world. Early detection of NSCLC can improve its outcome. The aim of this study was to identify the mutations of the KRAS and p53 genes in bronchoalveoar lavage (BAL) fluid for the early detection of peripheral NSCLC. We examined the DNA obtained from the tumor, nearby normal lung tissue, and matched BAL fluid for mutations in the KRAS and p53 genes; the material was obtained from 48 patients with peripheral NSCLC, and was analyzed by PCR-single strand conformation polymorphism and DNA sequencing. BAL fluids from 26 patients with benign lung disease were used as controls. Positive rates of KRAS and p53 mutations were distributed as follows: in NSCLC tissue, 52% and 58%; in BAL fluid of NSCLC patients, 38% and 44%; in normal lung tissue, 6% and 4%; and in BAL fluid of patients with benign lung disease, 8% and 4%. The combined detection of both KRAS and p53 mutations yielded a sensitivity of 66% for the diagnosis of peripheral NSCLC, which is markedly higher than that of cytology plus histology by first bronchoscopy (38%, p=0.008). In each patient with the 2 gene mutations in BAL fluid, mutation type and location were the same as those of the primary tumor. Our study indicates that the detection of the KRAS and p53 mutations in BAL fluids could be a helpful addition to cytology and histology examination for the diagnosis of peripheral NSCLC.

Does a p53 "Wild-type" Immunophenotype Exclude a Diagnosis of Endometrial Serous Carcinoma?

PubMed

Fadare, Oluwole; Roma, Andres A; Parkash, Vinita; Zheng, Wenxin; Walavalkar, Vighnesh

2018-01-01

An aberrant p53 immunophenotype may be identified in several histotypes of endometrial carcinoma, and is accordingly recognized to lack diagnostic specificity in and of itself. However, based on the high frequency with which p53 aberrations have historically been identified in endometrial serous carcinoma, a mutation-type immunophenotype is considered to be highly sensitive for the histotype. Using an illustrative case study and a review of the literature, we explore a relatively routine diagnostic question: whether the negative predictive value of a wild-type p53 immunophenotype for serous carcinoma is absolute, that is, whether a p53-wild type immunophenotype is absolutely incompatible with a diagnosis of serous carcinoma. The case is an advanced stage endometrial carcinoma that was reproducibly classified by pathologists from 3 institutions as serous carcinoma based on its morphologic features. By immunohistochemistry, the tumor was p53-wild type (DO-7 clone), diffusely positive for p16 (block positivity), and showed retained expression of PTEN, MSH2, MSH6, MLH1, and PMS2. Next generation sequencing showed that there indeed was an underlying mutation in TP53 (D393fs*78, R213*). The tumor was microsatellite stable, had a low mutational burden (4 mutations per MB), and displayed no mutations in the exonuclease domain of DNA polymerase epsilon (POLE) gene. Other genomic alterations included RB1 mutation (R46fs*19), amplifications in MYST3 and CRKL, and ARID1A deletion (splice site 5125-94_5138del108). A review of the recent literature identified 5 studies in which a total of 259 cases of serous carcinoma were whole-exome sequenced. The average TP53 mutational rate in endometrial serous carcinoma was only 75% (range, 60 to 88). A total of 12 (33%) of 36 immunohistochemical studies reported a p53-aberrant rate of <80% in endometrial serous carcinoma. We discuss in detail several potential explanations that may underlie the scenario of serous carcinoma-like morphology combined with p53-wild-type immunophenotype, including analytic limitations, a nonserous histotype displaying morphologic mimicry of serous carcinoma, and true biological phenomena (including the possibility of a TP53-independent pathway of endometrial serous carcinogenesis). Ultimately, our central thematic question is provisionally answered in the negative. At present, the available data would not support a categorical conclusion that a p53 alteration is a necessary and obligate component in the genesis and/or diagnosis of endometrial serous carcinoma. On the basis of their collective experience, the authors proffer some recommendations on the use of p53 immunohistochemistry in the histotyping of endometrial carcinomas.

p53 in breast cancer subtypes and new insights into response to chemotherapy.

PubMed

Bertheau, Philippe; Lehmann-Che, Jacqueline; Varna, Mariana; Dumay, Anne; Poirot, Brigitte; Porcher, Raphaël; Turpin, Elisabeth; Plassa, Louis-François; de Roquancourt, Anne; Bourstyn, Edwige; de Cremoux, Patricia; Janin, Anne; Giacchetti, Sylvie; Espié, Marc; de Thé, Hugues

2013-08-01

Despite an obvious central role of p53 in the hallmarks of cancer, TP53 status is not yet used for the management of breast cancer. Recent findings may lead to reconsider the role of p53 in breast cancer. TP53 mutations are the most frequent genetic alterations in breast cancer, observed in 30% of breast carcinomas. Their distribution is highly linked to molecular tumor subtypes found in 26% of luminal tumors (17% of luminal A, 41% of luminal B), in 50% of HER2 amplified tumors, in 69% of molecular apocrine breast carcinomas and in 88% of basal-like carcinomas. The type of mutation is linked to the tumor subtype with higher frequency of base-pair substitutions in luminal tumors, whereas molecular apocrine and basal-like tumors present much higher frequency of complex mutations (deletions/insertions). The timing of TP53 mutation also depends on the tumor subtype, being the first important event in luminal tumors but occurring after PTEN loss in basal-like tumors. Regarding response to cytotoxic chemotherapy, the situation is far from the p53-dependent apoptosis paradigm with subsequent clinical response. We reported that TP53 mutated non inflammatory locally advanced breast carcinomas had a high rate of complete pathological response to dose-dense doxorubicin-cyclophosphamide chemotherapy, while TP53 wild-type (WT) tumors never achieved complete response. Using human breast cancer xenograft models, we suggested that this could be due to the induction of senescence in TP53 WT tumor cells. A recent work confirmed these findings in MMTV-Wnt1 mammary tumors, showing that growth arrest and senescent phenotype, not apoptosis, were induced in TP53 WT tumors following doxorubicin treatment, while lack of arrest in mutant tumors resulted in aberrant mitoses, cell death and a superior clinical response. Furthermore, in ER positive (ER(+)) breast tumors, it has been recently reported that ER represses the p53-mediated apoptotic response induced by DNA damage. Taken together, these data can help to better understand p53-mediated response to doxorubicin-based chemotherapy in breast cancer: in ER(+) TP53 WT breast cancers, ER-induced inhibition of p53 apoptotic response would lead preferentially to tumor cell senescence and subsequent resistance to treatment. Conversely, in ER negative (ER(-)) TP53 mutated breast cancers, accumulation of genetic abnormalities would lead to mitotic catastrophe and subsequent better response. In view of these recent results, p53 impact in breast cancer should be reconsidered. Copyright © 2013 Elsevier Ltd. All rights reserved.

KRAS, BRAF genotyping reveals genetic heterogeneity of ovarian borderline tumors and associated implants

PubMed Central

2013-01-01

Background Patients diagnosed for a serous ovarian borderline tumor (s-BOT) typically present with an excellent clinical outcome. However there have been controversies concerning the prognostic impact of so-called implants, an extra ovarian spread occurring alongside the s-BOT in certain cases. It remains obscure whether these implants actually resemble metastasis owning the same genetic pattern as the ovarian primary or whether they develop independently. Methods The current study, in the aim of further clarifying the genetic origin of implants, assessed BRAF/KRAS hot spot mutations and the p53/p16INK4a immunophenotype of s-BOTs and corresponding implants (n = 49) of 15 patients by pyro-sequencing and immunostaining, respectively. Results A significant proportion of both s-BOTs and implants showed KRAS or BRAF mutation and though p16INK4a was found to be abundantly expressed, p53 immunoreactivity was rather low. When genotypes of BRAF/KRAS mutated s-BOTs and corresponding implants were compared no patient presented with a fully matching mutation profile of s-BOTs and all corresponding implants. Conclusions The current study reveals genetic heterogeneity of s-BOTs and implants, as none of the markers examined showed constant reciprocity. Hence, our findings may assist to explain the different clinical presentation of s-BOTs and implants and might encourage to applying more individualized follow up protocols. PMID:24139521

KRAS, BRAF genotyping reveals genetic heterogeneity of ovarian borderline tumors and associated implants.

PubMed

Heublein, Sabine; Grasse, Katinka; Hessel, Harald; Burges, Alexander; Lenhard, Miriam; Engel, Jutta; Kirchner, Thomas; Jeschke, Udo; Mayr, Doris

2013-10-18

Patients diagnosed for a serous ovarian borderline tumor (s-BOT) typically present with an excellent clinical outcome. However there have been controversies concerning the prognostic impact of so-called implants, an extra ovarian spread occurring alongside the s-BOT in certain cases. It remains obscure whether these implants actually resemble metastasis owning the same genetic pattern as the ovarian primary or whether they develop independently. The current study, in the aim of further clarifying the genetic origin of implants, assessed BRAF/KRAS hot spot mutations and the p53/p16INK4a immunophenotype of s-BOTs and corresponding implants (n=49) of 15 patients by pyro-sequencing and immunostaining, respectively. A significant proportion of both s-BOTs and implants showed KRAS or BRAF mutation and though p16INK4a was found to be abundantly expressed, p53 immunoreactivity was rather low. When genotypes of BRAF/KRAS mutated s-BOTs and corresponding implants were compared no patient presented with a fully matching mutation profile of s-BOTs and all corresponding implants. The current study reveals genetic heterogeneity of s-BOTs and implants, as none of the markers examined showed constant reciprocity. Hence, our findings may assist to explain the different clinical presentation of s-BOTs and implants and might encourage to applying more individualized follow up protocols.

DETECTION OF K-RAS AND P53 MUTATIONS IN SPUTUM SAMPLES OF LUNG CANCER PATIENTS USING LASER CAPTURE MICRODISSECTION MICROSCOPE AND MUTATION ANALYSIS

EPA Science Inventory

Detection of K-ras and p53 Mutations in Sputum Samples of Lung Cancer Patients Using Laser Capture Microdissection Microscope and Mutation Analysis

Phouthone Keohavong a,*, Wei-Min Gao a, Kui-Cheng Zheng a, Hussam Mady b, Qing Lan c, Mona Melhem b, and Judy Mumford d.
<...

Molecular biomarkers for progression of intraductal papillary mucinous neoplasm of the pancreas.

PubMed

Kuboki, Yuko; Shimizu, Kyoko; Hatori, Takashi; Yamamoto, Masakazu; Shibata, Noriyuki; Shiratori, Keiko; Furukawa, Toru

2015-03-01

We aimed to identify molecular biomarkers for assessing the progression of intraductal papillary mucinous neoplasm of the pancreas (IPMN). We retrospectively investigated molecular aberrations and their associations with clinicopathological features in 172 IPMNs. GNAS and KRAS mutations were detected in 48% and 56% of IPMNs, respectively. No mutations of EGFR, PIK3CA GNAO1, GNAQ, or GNAI2 were observed. Significant associations were observed between IPMN morphological types and GNAS mutations, KRAS mutations, the expression of phosphorylated MAPK (pMAPK), AKT, and phosphorylated AKT (pAKT), nuclear accumulation of β-catenin, SMAD4 loss, and TP53 overexpression; histological grades and the expression of EGFR, pMAPK, AKT, and pAKT, the nuclear β-catenin, SMAD4 loss, and TP53 overexpression; invasive phenotypes and KRAS mutations, the nuclear β-catenin, and SMAD4 loss; and prognosis and SMAD4 loss and TP53 overexpression. Multivariate analysis to compare prognostic impacts of multiple molecular features revealed that TP53 overexpression was an independent prognostic factor (P = 0.030; hazard ratio, 5.533). These results indicate that mutations in GNAS and KRAS, the expression of EGFR and pMAPK, the nuclear β-catenin, SMAD4 loss, and TP53 overexpression may be relevant for assessing the clinical course of IPMN, including its progression into different morphological types, invasion, and prognosis.

[A preliminary study on p53 gene in lung cancer tissues of workers exposed to silica and welding fumes].

PubMed

Liu, B; Zhou, P; Miao, Q

1997-05-01

Mutations of suppressor gene p53 was studied in 36 cases of silica related lung cancer and 6 cases of welding fume related lung cancer with immunohistochemical and PCR-SSCP methods. Cancer tissues were embedded in paraffin and stored for 13.4 years in average. Results revealed that there was abnormal mobility shift of electrophoresis in 18 cases with 20 point mutations of 42 specimens tested, accounted for 42.9%, and 50% (10/20) of the mutations were clustered in exon 8. This finding differed from mutational spectrum of gene in non-occupational lung cancer, in which mutation frequency of exon 8 ranged from 17.5% to 23.5%. Gene mutation frequency in varied pathological categories of pneumoconiosis related lung cancer also differed from that in common lung cancer. In the latter, the highest one was in small cell lung cancer (70%) and the lowest in adenocarcinoma (33%), but in the former, the highest in adenocarcinoma (53.9%) and the lowest in small cell lung cancer (30.8%). Immunohistochemical observations also showed a very high prevalence of p53 gene mutation expression (46.9%). Sequencing, which was determined in two cases of this study, revealed that two point mutations all occurred in non-hotspot codon 144 of p53 gene. Difference in gene mutation spectrum suggests that there exist specific carcinogens and carcinogenesis in silica and welding fume related lung cancer.

R248Q mutation--Beyond p53-DNA binding.

PubMed

Ng, Jeremy W K; Lama, Dilraj; Lukman, Suryani; Lane, David P; Verma, Chandra S; Sim, Adelene Y L

2015-12-01

R248 in the DNA binding domain (DBD) of p53 interacts directly with the minor groove of DNA. Earlier nuclear magnetic resonance (NMR) studies indicated that the R248Q mutation resulted in conformation changes in parts of DBD far from the mutation site. However, how information propagates from the mutation site to the rest of the DBD is still not well understood. We performed a series of all-atom molecular dynamics (MD) simulations to dissect sterics and charge effects of R248 on p53-DBD conformation: (i) wild-type p53 DBD; (ii) p53 DBD with an electrically neutral arginine side-chain; (iii) p53 DBD with R248A; (iv) p53 DBD with R248W; and (v) p53 DBD with R248Q. Our results agree well with experimental observations of global conformational changes induced by the R248Q mutation. Our simulations suggest that both charge- and sterics are important in the dynamics of the loop (L3) where the mutation resides. We show that helix 2 (H2) dynamics is altered as a result of a change in the hydrogen bonding partner of D281. In turn, neighboring L1 dynamics is altered: in mutants, L1 predominantly adopts the recessed conformation and is unable to interact with the major groove of DNA. We focused our attention the R248Q mutant that is commonly found in a wide range of cancer and observed changes at the zinc-binding pocket that might account for the dominant negative effects of R248Q. Furthermore, in our simulations, the S6/S7 turn was more frequently solvent exposed in R248Q, suggesting that there is a greater tendency of R248Q to partially unfold and possibly lead to an increased aggregation propensity. Finally, based on the observations made in our simulations, we propose strategies for the rescue of R248Q mutants. © 2015 Wiley Periodicals, Inc.

[Molecular mechanisms of lung cancer development at its different stages in nuclear industry workers].

PubMed

Rusinova, G G; Vyazovskaya, N S; Azizova, T V; Revina, V S; Glazkova, I V; Generozov, E V; Zakharzhevskaya, N B; Guryanov, M Yu; Belosokhov, M V; Osovets, S V

2015-01-01

to assess mutational events in exons 5, 7, and 8 of the p53 gene and to reveal mutant p53 protein in verified cases of morphologically altered (proliferative and precancerous changes, lung cancer) and histologically unaltered, lung tissues in workers exposed to occupational radiation. The investigation used formalin-fixed paraffin-embedded unaltered and altered lung tissue blocks (FFPBs) obtained from the human radiobiological tissue repository. The shelf-life of FFPBs was 5-31 years. An immunohistochemical technique using mouse antibodies against p53 protein (, Denmark), stained with diaminobenzidine (DAB) chromogen, was employed to determine p53 protein. DNA was isolated from lung tissue FFPBs with QIAmp DNA FFPE Tissue Kit, (, USA). Polymerase chain reaction (PCR) was performed to amplify the p53 gene exons 5, 7, and 8 selected for examination, by applying the sequences of genes and primers, the specificity of which was checked using the online resource (http://www.ncbi.nlm.nih.gov/blast). PCR products were detected by temporal temperature gradient gel-electrophoresis and the Sanger sequencing method. The obtained DNA fragments were analyzed on a sequencer ABI Prism 3100 Genetic Analizer (, USA). Computer-aided DNA analysis was made using the BLAST program. A package of applied Statistica 6.0 programs was employed for statistical data processing. Results. Immunohistochemical analysis showed that mutant p53 protein was absent in the cells of unaltered lung tissue and the number of cells with mutant p53 protein increased in all the patients with proliferative and precancerous changes and lung cancer, suggesting p53 protein dysfunction. The total number of p53 gene mutations in exons 5, 7, and 8, if there were proliferative and precancerous lung tissue changes and lung cancer, were 25, 20, and 40%, respectively. All the found mutations were transversions (the substitution of purine for pyrimidine or, conversely), indicating the action of exogenous mutagens. The results of this investigation have confirmed other investigators' data showing that p53 gene mutations in lung cancer are observed in 40-70% of cases. The differences in the number of cases of altered lung tissue with mutations in the p53 gene (not more than 40%) and in those of p53 protein expression were found in 100%, suggesting the regulation of p53 gene function in the cell at multiple levels.

Methylation, expression, and mutation analysis of the cell cycle control genes in human brain tumors.

PubMed

Yin, Dong; Xie, Dong; Hofmann, Wolf-Karsten; Miller, Carl W; Black, Keith L; Koeffler, H Phillip

2002-11-28

Methylation status of the p15(INK4B), p16(INK4A), p14(ARF) and retinoblastoma (RB) genes was studied using methylation specific polymerase chain reaction (MSP) in 85 human brain tumors of various subtypes and four normal brain samples. These genes play an important role in the control of the cell cycle. Twenty-four out of 85 cases (28%) had at least one of these genes methylated. The frequency of p14(ARF) methylation was 15 out of 85 (18%) cases, and the expression of p14(ARF) in methylated gliomas was significantly lower than in unmethylated gliomas. The incidence of methylation of p15(INK4B), p16(INK4A) and RB gene was 4%, 7%, and 4%, respectively. Samples with p14(ARF) methylation did not have p16(INK4A) methylation even though both genes physically overlap. None of the target genes was methylated in the normal brain samples. In addition, the p53 gene was mutated in 19 out of 85 (22%) samples as determined by single strand conformation polymorphism (SSCP) analysis and DNA sequencing. Thirty out of 85 (35%) brain tumors had either a p53 mutation or methylation of p14(ARF). Also, the p14(ARF) expression in p53 wild-type gliomas was lower than levels in p53 mutated gliomas. This finding is consistent with wild-type p53 being able to autoregulate its levels by down-regulating expression of p14(ARF). In summary, inactivation of the apoptosis pathway that included the p14(ARF) and p53 genes by hypermethylation and mutation, respectively, occurred frequently in human brain tumors. Down-regulation of p14(ARF) in gliomas was associated with hypermethylation of its promoter and the presence of a wild-type p53 in these samples.

Mutations in TP53 and JAK2 are independent prognostic biomarkers in B-cell precursor acute lymphoblastic leukaemia.

PubMed

Forero-Castro, Maribel; Robledo, Cristina; Benito, Rocío; Bodega-Mayor, Irene; Rapado, Inmaculada; Hernández-Sánchez, María; Abáigar, María; Maria Hernández-Sánchez, Jesús; Quijada-Álamo, Miguel; María Sánchez-Pina, José; Sala-Valdés, Mónica; Araujo-Silva, Fernanda; Kohlmann, Alexander; Luis Fuster, José; Arefi, Maryam; de Las Heras, Natalia; Riesco, Susana; Rodríguez, Juan N; Hermosín, Lourdes; Ribera, Jordi; Camos Guijosa, Mireia; Ramírez, Manuel; de Heredia Rubio, Cristina Díaz; Barragán, Eva; Martínez, Joaquín; Ribera, José M; Fernández-Ruiz, Elena; Hernández-Rivas, Jesús-María

2017-07-11

In B-cell precursor acute lymphoblastic leukaemia (B-ALL), the identification of additional genetic alterations associated with poor prognosis is still of importance. We determined the frequency and prognostic impact of somatic mutations in children and adult cases with B-ALL treated with Spanish PETHEMA and SEHOP protocols. Mutational status of hotspot regions of TP53, JAK2, PAX5, LEF1, CRLF2 and IL7R genes was determined by next-generation deep sequencing in 340 B-ALL patients (211 children and 129 adults). The associations between mutation status and clinicopathological features at the time of diagnosis, treatment outcome and survival were assessed. Univariate and multivariate survival analyses were performed to identify independent prognostic factors associated with overall survival (OS), event-free survival (EFS) and relapse rate (RR). A mutation rate of 12.4% was identified. The frequency of adult mutations was higher (20.2% vs 7.6%, P=0.001). TP53 was the most frequently mutated gene (4.1%), followed by JAK2 (3.8%), CRLF2 (2.9%), PAX5 (2.4%), LEF1 (0.6%) and IL7R (0.3%). All mutations were observed in B-ALL without ETV6-RUNX1 (P=0.047) or BCR-ABL1 fusions (P<0.0001). In children, TP53mut was associated with lower OS (5-year OS: 50% vs 86%, P=0.002) and EFS rates (5-year EFS: 50% vs 78.3%, P=0.009) and higher RR (5-year RR: 33.3% vs 18.6% P=0.037), and was independently associated with higher RR (hazard ratio (HR)=4.5; P=0.04). In adults, TP53mut was associated with a lower OS (5-year OS: 0% vs 43.3%, P=0.019) and a higher RR (5-year RR: 100% vs 61.4%, P=0.029), whereas JAK2mut was associated with a lower EFS (5-year EFS: 0% vs 30.6%, P=0.035) and a higher RR (5-year RR: 100% vs 60.4%, P=0.002). TP53mut was an independent risk factor for shorter OS (HR=2.3; P=0.035) and, together with JAK2mut, also were independent markers of poor prognosis for RR (TP53mut: HR=5.9; P=0.027 and JAK2mut: HR=5.6; P=0.036). TP53mut and JAK2mut are potential biomarkers associated with poor prognosis in B-ALL patients.

Chk1/2 inhibition overcomes the cisplatin resistance of head and neck cancer cells secondary to the loss of functional p53

PubMed Central

Gadhikar, Mayur A.; Sciuto, Maria Rita; Alves, Marcus Vinicius Ortega; Pickering, Curtis R.; Osman, Abdullah A.; Neskey, David M.; Zhao, Mei; Fitzgerald, Alison L.; Myers, Jeffrey N.; Frederick, Mitchell J

2014-01-01

Despite the use of multimodality therapy employing cisplatin to treat patients with advanced stage head and neck squamous cell carcinoma (HNSCC), there is an unacceptably high rate of treatment failure. TP53 is the most commonly mutated gene in HNSCC, and the impact of p53 mutation on response to cisplatin treatment is poorly understood. Here we show unambiguously that wild type TP53 (wtp53) is associated with sensitivity of HNSCC cells to cisplatin treatment while mutation or loss of TP53 is associated with cisplatin resistance. We also demonstrate that senescence is the major cellular response to cisplatin in wtp53 HNSCC cells and that cisplatin resistance in p53 null or mutant TP53 cells is due to their lack of senescence. Given the dependence on Chk1/2 kinases to mediate the DNA damage response in p53 deficient cells, there is potential to exploit this to therapeutic advantage through targeted inhibition of the Chk1/2 kinases. Treatment of p53 deficient HNSCC cells with the Chk inhibitor AZD7762 sensitizes them to cisplatin through induction of mitotic cell death. This is the first report demonstrating the ability of a Chk kinase inhibitor to sensitize TP53-deficient HNSCC to cisplatin in a synthetic lethal manner, which has significance given the frequency of TP53 mutations in this disease and because cisplatin has become part of standard therapy for aggressive HNSCC tumors. These pre-clinical data provide evidence that a personalized approach to the treatment of HNSCC based on Chk inhibition in p53 mutant tumors may be feasible. PMID:23839309

Structure-Based Analysis Reveals Cancer Missense Mutations Target Protein Interaction Interfaces.

PubMed

Engin, H Billur; Kreisberg, Jason F; Carter, Hannah

2016-01-01

Recently it has been shown that cancer mutations selectively target protein-protein interactions. We hypothesized that mutations affecting distinct protein interactions involving established cancer genes could contribute to tumor heterogeneity, and that novel mechanistic insights might be gained into tumorigenesis by investigating protein interactions under positive selection in cancer. To identify protein interactions under positive selection in cancer, we mapped over 1.2 million nonsynonymous somatic cancer mutations onto 4,896 experimentally determined protein structures and analyzed their spatial distribution. In total, 20% of mutations on the surface of known cancer genes perturbed protein-protein interactions (PPIs), and this enrichment for PPI interfaces was observed for both tumor suppressors (Odds Ratio 1.28, P-value < 10(-4)) and oncogenes (Odds Ratio 1.17, P-value < 10(-3)). To study this further, we constructed a bipartite network representing structurally resolved PPIs from all available human complexes in the Protein Data Bank (2,864 proteins, 3,072 PPIs). Analysis of frequently mutated cancer genes within this network revealed that tumor-suppressors, but not oncogenes, are significantly enriched with functional mutations in homo-oligomerization regions (Odds Ratio 3.68, P-Value < 10(-8)). We present two important examples, TP53 and beta-2-microglobulin, for which the patterns of somatic mutations at interfaces provide insights into specifically perturbed biological circuits. In patients with TP53 mutations, patient survival correlated with the specific interactions that were perturbed. Moreover, we investigated mutations at the interface of protein-nucleotide interactions and observed an unexpected number of missense mutations but not silent mutations occurring within DNA and RNA binding sites. Finally, we provide a resource of 3,072 PPI interfaces ranked according to their mutation rates. Analysis of this list highlights 282 novel candidate cancer genes that encode proteins participating in interactions that are perturbed recurrently across tumors. In summary, mutation of specific protein interactions is an important contributor to tumor heterogeneity and may have important implications for clinical outcomes.

Constant p53 Pathway Inactivation in a Large Series of Soft Tissue Sarcomas with Complex Genetics

PubMed Central

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

2010-01-01

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

The Role of BRCA1/BARD1 Heterodimers in the Mitosis-Interphase Transition

DTIC Science & Technology

2007-05-01

53 4 INTRODUCTION Germ line mutations in the BRCA1 gene predispose to breast and/or ovarian cancer (Miki, et al...Targeted mutations of breast cancer susceptibility gene homologs in mice: lethal phenotypes of Brca1, Brca2, Brca1/Brca2, Brca1/p53, and Brca2/p53...Ludwig, T., Chapman, D.L., Papaioannou, V.E., and Efstratiadis, A. (1997). Targeted mutations of breast cancer susceptibility gene homo- logs in mice

FBXW7-mutated colorectal cancer cells exhibit aberrant expression of phosphorylated-p53 at Serine-15

PubMed Central

Normatova, Makhliyo; Babaei-Jadidi, Roya; Tomlinson, Ian; Nateri, Abdolrahman S.

2015-01-01

FBXW7 mutations occur in a variety of human cancers including colorectal cancer (CRC). Elucidating its mechanism of action has become crucial for cancer therapy; however, it is also complicated by the fact that FBXW7 can influence many pathways due to its role as an E3-ubiquitin ligase in proteasome degradation. FBXW7 and TP53 are tumour suppressors intensively implicated in colorectal carcinogenesis. Deletion mutations in these two genes in animal models mark the progression from adenoma to carcinoma. Although still largely unknown, the last defense mechanism against CRC at the molecular level could be through a synergistic effect of the two genes. The underlying mechanism requires further investigation. In our laboratory, we have used a phospho-kinase profiler array to illustrate a potential molecular link between FBXW7 and p53 in CRC cells. In vitro and in vivo assessments demonstrated aberrant induction of phosphorylated p53 at Serine 15 [phospho-p53(Ser15)] in human FBXW7-deficient CRC cells as compared to their FBXW7-wild-type counterparts. FBXW7 loss in HCT116 cells promoted resistance to oxaliplatin. Immunoblotting data further confirmed that reduction of phospho-p53(Ser15) may contribute to the decreased efficacy of therapy in FBXW7-mutated CRC cells. The findings may suggest the applicability of phospho-p53(Ser15) as an indicative marker of FBXW7-mutations. Phospho-p53(Ser15) regulation by FBXW7 E3-ligase activity could provide important clues for understanding FBXW7 behavior in tumour progression and grounds for its clinical applicability thereafter. PMID:25860929

The role of p53 in combination radioimmunotherapy with 64Cu-DOTA-cetuximab and cisplatin in a mouse model of colorectal cancer.

PubMed

Guo, Yunjun; Parry, Jesse J; Laforest, Richard; Rogers, Buck E; Anderson, Carolyn J

2013-09-01

Radioimmunotherapy has been successfully used in the treatment of lymphoma but thus far has not demonstrated significant efficacy in humans beyond disease stabilization in solid tumors. Radioimmunotherapy with (64)Cu was highly effective in a hamster model of colorectal cancer, but targeted radiotherapies with this radionuclide have since not shown as much success. It is widely known that mutations in key proteins play a role in the success or failure of cancer therapies. For example, the KRAS mutation is predictive of poor response to anti-epidermal growth factor receptor therapies in colorectal cancer, whereas p53 is frequently mutated in tumors, causing resistance to multiple therapeutic regimens. We previously showed that nuclear localization of (64)Cu-labeled DOTA-cetuximab was enhanced in p53 wild-type tumor cells. Here, we examine the role of p53 in the response to radioimmunotherapy with (64)Cu-DOTA-cetuximab in KRAS-mutated HCT116 tumor-bearing mice, with and without cisplatin, which upregulates wild-type p53. Experiments with HCT116 cells that are p53 +/+ (p53 wild-type) and -/- (p53 null) grown in cell culture demonstrated that preincubation with cisplatin increased expression of p53 and subsequently enhanced localization of (64)Cu from (64)Cu-acetate and (64)Cu-DOTA-cetuximab to the tumor cell nuclei. Radioimmunotherapy studies in p53-positive HCT116 tumor-bearing mice, receiving either radioimmunotherapy alone or in combination with cisplatin, showed significantly longer survival in mice receiving unlabeled cetuximab or cisplatin alone or in combination (all, P < 0.01). In contrast, the p53-negative tumor-bearing mice treated with radioimmunotherapy alone or combined with cisplatin showed no survival advantage, compared with control groups (all, P > 0.05). Together, these data suggest that (64)Cu specifically delivered to epidermal growth factor receptor-positive tumors by cetuximab can suppress tumor growth despite the KRAS status and present opportunities for personalized clinical treatment strategies in colorectal cancer.

CRISPR-mediated direct mutation of cancer genes in the mouse liver.

PubMed

Xue, Wen; Chen, Sidi; Yin, Hao; Tammela, Tuomas; Papagiannakopoulos, Thales; Joshi, Nikhil S; Cai, Wenxin; Yang, Gillian; Bronson, Roderick; Crowley, Denise G; Zhang, Feng; Anderson, Daniel G; Sharp, Phillip A; Jacks, Tyler

2014-10-16

The study of cancer genes in mouse models has traditionally relied on genetically-engineered strains made via transgenesis or gene targeting in embryonic stem cells. Here we describe a new method of cancer model generation using the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins) system in vivo in wild-type mice. We used hydrodynamic injection to deliver a CRISPR plasmid DNA expressing Cas9 and single guide RNAs (sgRNAs) to the liver that directly target the tumour suppressor genes Pten (ref. 5) and p53 (also known as TP53 and Trp53) (ref. 6), alone and in combination. CRISPR-mediated Pten mutation led to elevated Akt phosphorylation and lipid accumulation in hepatocytes, phenocopying the effects of deletion of the gene using Cre-LoxP technology. Simultaneous targeting of Pten and p53 induced liver tumours that mimicked those caused by Cre-loxP-mediated deletion of Pten and p53. DNA sequencing of liver and tumour tissue revealed insertion or deletion mutations of the tumour suppressor genes, including bi-allelic mutations of both Pten and p53 in tumours. Furthermore, co-injection of Cas9 plasmids harbouring sgRNAs targeting the β-catenin gene and a single-stranded DNA oligonucleotide donor carrying activating point mutations led to the generation of hepatocytes with nuclear localization of β-catenin. This study demonstrates the feasibility of direct mutation of tumour suppressor genes and oncogenes in the liver using the CRISPR/Cas system, which presents a new avenue for rapid development of liver cancer models and functional genomics.

[Interaction between p53 and MDM2 in human lung cancer cells].

PubMed

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

2014-01-01

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

Structures of oncogenic, suppressor and rescued p53 core-domain variants: mechanisms of mutant p53 rescue

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

Wallentine, Brad D.; Wang, Ying; Tretyachenko-Ladokhina, Vira

2013-10-01

X-ray crystallographic structures of four p53 core-domain variants were determined in order to gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53. To gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53, X-ray crystallographic structures of four p53 core-domain variants were determined. These include an oncogenic mutant, V157F, two single-site suppressor mutants, N235K and N239Y, and the rescued cancer mutant V157F/N235K/N239Y. The V157F mutationmore » substitutes a smaller hydrophobic valine with a larger hydrophobic phenylalanine within strand S4 of the hydrophobic core. The structure of this cancer mutant shows no gross structural changes in the overall fold of the p53 core domain, only minor rearrangements of side chains within the hydrophobic core of the protein. Based on biochemical analysis, these small local perturbations induce instability in the protein, increasing the free energy by 3.6 kcal mol{sup −1} (15.1 kJ mol{sup −1}). Further biochemical evidence shows that each suppressor mutation, N235K or N239Y, acts individually to restore thermodynamic stability to V157F and that both together are more effective than either alone. All rescued mutants were found to have wild-type DNA-binding activity when assessed at a permissive temperature, thus pointing to thermodynamic stability as the critical underlying variable. Interestingly, thermodynamic analysis shows that while N239Y demonstrates stabilization of the wild-type p53 core domain, N235K does not. These observations suggest distinct structural mechanisms of rescue. A new salt bridge between Lys235 and Glu198, found in both the N235K and rescued cancer mutant structures, suggests a rescue mechanism that relies on stabilizing the β-sandwich scaffold. On the other hand, the substitution N239Y creates an advantageous hydrophobic contact between the aromatic ring of this tyrosine and the adjacent Leu137. Surprisingly, the rescued cancer mutant shows much larger structural deviations than the cancer mutant alone when compared with wild-type p53. These suppressor mutations appear to rescue p53 function by creating novel intradomain interactions that stabilize the core domain, allowing compensation for the destabilizing V157F mutation.« less

A SENSITIVE IMMUNOFLUORESCENCE ASSAY FOR DETECTION OF P53 PROTEIN ACCUMULATION IN SPUTUM

EPA Science Inventory

p53 mutations are common genetic alterations in lung cancers and usually result in p53 protein accumulation in tumor cells. Sputum is noninvasive to collect and ideal for screening p53 abnormalities. This study was to determine the feasibility of detecting p53 protein accumulatio...

Driver mutations in TP53 are ubiquitous in high grade serous carcinoma of the ovary.

PubMed

Ahmed, Ahmed Ashour; Etemadmoghadam, Dariush; Temple, Jillian; Lynch, Andy G; Riad, Mohamed; Sharma, Raghwa; Stewart, Colin; Fereday, Sian; Caldas, Carlos; Defazio, Anna; Bowtell, David; Brenton, James D

2010-05-01

Numerous studies have tested the association between TP53 mutations in ovarian cancer and prognosis but these have been consistently confounded by limitations in study design, methodology, and/or heterogeneity in the sample cohort. High-grade serous (HGS) carcinoma is the most clinically important histological subtype of ovarian cancer. As these tumours may arise from the ovary, Fallopian tube or peritoneum, they are collectively referred to as high-grade pelvic serous carcinoma (HGPSC). To identify the true prevalence of TP53 mutations in HGPSC, we sequenced exons 2-11 and intron-exon boundaries in tumour DNA from 145 patients. HGPSC cases were defined as having histological grade 2 or 3 and FIGO stage III or IV. Surprisingly, pathogenic TP53 mutations were identified in 96.7% (n = 119/123) of HGPSC cases. Molecular and pathological review of mutation-negative cases showed evidence of p53 dysfunction associated with copy number gain of MDM2 or MDM4, or indicated the exclusion of samples as being low-grade serous tumours or carcinoma of uncertain primary site. Overall, p53 dysfunction rate approached 100% of confirmed HGPSCs. No association between TP53 mutation and progression-free or overall survival was found. From this first comprehensive mapping of TP53 mutation rate in a homogeneous group of HGPSC patients, we conclude that mutant TP53 is a driver mutation in the pathogenesis of HGPSC cancers. Because TP53 mutation is almost invariably present in HGPSC, it is not of substantial prognostic or predictive significance. Copyright (c) 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Gene Mutation Profiles in Primary Diffuse Large B Cell Lymphoma of Central Nervous System: Next Generation Sequencing Analyses

PubMed Central

Todorovic Balint, Milena; Jelicic, Jelena; Mihaljevic, Biljana; Kostic, Jelena; Stanic, Bojana; Balint, Bela; Pejanovic, Nadja; Lucic, Bojana; Tosic, Natasa; Marjanovic, Irena; Stojiljkovic, Maja; Karan-Djurasevic, Teodora; Perisic, Ognjen; Rakocevic, Goran; Popovic, Milos; Raicevic, Sava; Bila, Jelena; Antic, Darko; Andjelic, Bosko; Pavlovic, Sonja

2016-01-01

The existence of a potential primary central nervous system lymphoma-specific genomic signature that differs from the systemic form of diffuse large B cell lymphoma (DLBCL) has been suggested, but is still controversial. We investigated 19 patients with primary DLBCL of central nervous system (DLBCL CNS) using the TruSeq Amplicon Cancer Panel (TSACP) for 48 cancer-related genes. Next generation sequencing (NGS) analyses have revealed that over 80% of potentially protein-changing mutations were located in eight genes (CTNNB1, PIK3CA, PTEN, ATM, KRAS, PTPN11, TP53 and JAK3), pointing to the potential role of these genes in lymphomagenesis. TP53 was the only gene harboring mutations in all 19 patients. In addition, the presence of mutated TP53 and ATM genes correlated with a higher total number of mutations in other analyzed genes. Furthermore, the presence of mutated ATM correlated with poorer event-free survival (EFS) (p = 0.036). The presence of the mutated SMO gene correlated with earlier disease relapse (p = 0.023), inferior event-free survival (p = 0.011) and overall survival (OS) (p = 0.017), while mutations in the PTEN gene were associated with inferior OS (p = 0.048). Our findings suggest that the TP53 and ATM genes could be involved in the molecular pathophysiology of primary DLBCL CNS, whereas mutations in the PTEN and SMO genes could affect survival regardless of the initial treatment approach. PMID:27164089

Chromosome 3 Anomalies Investigated by Genome Wide SNP Analysis of Benign, Low Malignant Potential and Low Grade Ovarian Serous Tumours

PubMed Central

Birch, Ashley H.; Arcand, Suzanna L.; Oros, Kathleen K.; Rahimi, Kurosh; Watters, A. Kevin; Provencher, Diane; Greenwood, Celia M.; Mes-Masson, Anne-Marie; Tonin, Patricia N.

2011-01-01

Ovarian carcinomas exhibit extensive heterogeneity, and their etiology remains unknown. Histological and genetic evidence has led to the proposal that low grade ovarian serous carcinomas (LGOSC) have a different etiology than high grade carcinomas (HGOSC), arising from serous tumours of low malignant potential (LMP). Common regions of chromosome (chr) 3 loss have been observed in all types of serous ovarian tumours, including benign, suggesting that these regions contain genes important in the development of all ovarian serous carcinomas. A high-density genome-wide genotyping bead array technology, which assayed >600,000 markers, was applied to a panel of serous benign and LMP tumours and a small set of LGOSC, to characterize somatic events associated with the most indolent forms of ovarian disease. The genomic patterns inferred were related to TP53, KRAS and BRAF mutations. An increasing frequency of genomic anomalies was observed with pathology of disease: 3/22 (13.6%) benign cases, 40/53 (75.5%) LMP cases and 10/11 (90.9%) LGOSC cases. Low frequencies of chr3 anomalies occurred in all tumour types. Runs of homozygosity were most commonly observed on chr3, with the 3p12-p11 candidate tumour suppressor region the most frequently homozygous region in the genome. An LMP harboured a homozygous deletion on chr6 which created a GOPC-ROS1 fusion gene, previously reported as oncogenic in other cancer types. Somatic TP53, KRAS and BRAF mutations were not observed in benign tumours. KRAS-mutation positive LMP cases displayed significantly more chromosomal aberrations than BRAF-mutation positive or KRAS and BRAF mutation negative cases. Gain of 12p, which harbours the KRAS gene, was particularly evident. A pathology review reclassified all TP53-mutation positive LGOSC cases, some of which acquired a HGOSC status. Taken together, our results support the view that LGOSC could arise from serous benign and LMP tumours, but does not exclude the possibility that HGOSC may derive from LMP tumours. PMID:22163003

Chromosome 3 anomalies investigated by genome wide SNP analysis of benign, low malignant potential and low grade ovarian serous tumours.

PubMed

Birch, Ashley H; Arcand, Suzanna L; Oros, Kathleen K; Rahimi, Kurosh; Watters, A Kevin; Provencher, Diane; Greenwood, Celia M; Mes-Masson, Anne-Marie; Tonin, Patricia N

2011-01-01

Ovarian carcinomas exhibit extensive heterogeneity, and their etiology remains unknown. Histological and genetic evidence has led to the proposal that low grade ovarian serous carcinomas (LGOSC) have a different etiology than high grade carcinomas (HGOSC), arising from serous tumours of low malignant potential (LMP). Common regions of chromosome (chr) 3 loss have been observed in all types of serous ovarian tumours, including benign, suggesting that these regions contain genes important in the development of all ovarian serous carcinomas. A high-density genome-wide genotyping bead array technology, which assayed >600,000 markers, was applied to a panel of serous benign and LMP tumours and a small set of LGOSC, to characterize somatic events associated with the most indolent forms of ovarian disease. The genomic patterns inferred were related to TP53, KRAS and BRAF mutations. An increasing frequency of genomic anomalies was observed with pathology of disease: 3/22 (13.6%) benign cases, 40/53 (75.5%) LMP cases and 10/11 (90.9%) LGOSC cases. Low frequencies of chr3 anomalies occurred in all tumour types. Runs of homozygosity were most commonly observed on chr3, with the 3p12-p11 candidate tumour suppressor region the most frequently homozygous region in the genome. An LMP harboured a homozygous deletion on chr6 which created a GOPC-ROS1 fusion gene, previously reported as oncogenic in other cancer types. Somatic TP53, KRAS and BRAF mutations were not observed in benign tumours. KRAS-mutation positive LMP cases displayed significantly more chromosomal aberrations than BRAF-mutation positive or KRAS and BRAF mutation negative cases. Gain of 12p, which harbours the KRAS gene, was particularly evident. A pathology review reclassified all TP53-mutation positive LGOSC cases, some of which acquired a HGOSC status. Taken together, our results support the view that LGOSC could arise from serous benign and LMP tumours, but does not exclude the possibility that HGOSC may derive from LMP tumours.

Actin cytoskeleton organization, cell surface modification and invasion rate of 5 glioblastoma cell lines differing in PTEN and p53 status

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

Djuzenova, Cholpon S., E-mail: djuzenova_t@ukw.de; Fiedler, Vanessa; Memmel, Simon

Glioblastoma cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores the relationship between the invasion capacity of 5 glioblastoma cell lines differing in p53 and PTEN status, expression of mTOR and several other marker proteins involved in cell invasion, actin cytoskeleton organization and cell morphology. We found that two glioblastoma lines mutated in both p53 and PTEN genes (U373-MG and SNB19) exhibited the highest invasion rates through the Matrigel or collagen matrix. In DK-MG (p53wt/PTENwt) and GaMG (p53mut/PTENwt) cells, F-actin mainly occurred in the numerous stress fibers spanning the cytoplasm, whereas U87-MG (p53wt/PTENmut),more » U373-MG and SNB19 (both p53mut/PTENmut) cells preferentially expressed F-actin in filopodia and lamellipodia. Scanning electron microscopy confirmed the abundant filopodia and lamellipodia in the PTEN mutated cell lines. Interestingly, the gene profiling analysis revealed two clusters of cell lines, corresponding to the most (U373-MG and SNB19, i.e. p53 and PTEN mutated cells) and less invasive phenotypes. The results of this study might shed new light on the mechanisms of glioblastoma invasion. - Highlights: • We examine 5 glioblastoma lines on the invasion capacity and actin cytoskeleton. • Glioblastoma cell lines mutated in both p53 and PTEN were the most invasive. • Less invasive cells showed much less lamellipodia, but more actin stress fibers. • A mechanism for the differences in tumor cell invasion is proposed.« less

p53 downregulates the Fanconi anaemia DNA repair pathway

PubMed Central

Jaber, Sara; Toufektchan, Eléonore; Lejour, Vincent; Bardot, Boris; Toledo, Franck

2016-01-01

Germline mutations affecting telomere maintenance or DNA repair may, respectively, cause dyskeratosis congenita or Fanconi anaemia, two clinically related bone marrow failure syndromes. Mice expressing p53Δ31, a mutant p53 lacking the C terminus, model dyskeratosis congenita. Accordingly, the increased p53 activity in p53Δ31/Δ31 fibroblasts correlated with a decreased expression of 4 genes implicated in telomere syndromes. Here we show that these cells exhibit decreased mRNA levels for additional genes contributing to telomere metabolism, but also, surprisingly, for 12 genes mutated in Fanconi anaemia. Furthermore, p53Δ31/Δ31 fibroblasts exhibit a reduced capacity to repair DNA interstrand crosslinks, a typical feature of Fanconi anaemia cells. Importantly, the p53-dependent downregulation of Fanc genes is largely conserved in human cells. Defective DNA repair is known to activate p53, but our results indicate that, conversely, an increased p53 activity may attenuate the Fanconi anaemia DNA repair pathway, defining a positive regulatory feedback loop. PMID:27033104

p53 downregulates the Fanconi anaemia DNA repair pathway.

PubMed

Jaber, Sara; Toufektchan, Eléonore; Lejour, Vincent; Bardot, Boris; Toledo, Franck

2016-04-01

Germline mutations affecting telomere maintenance or DNA repair may, respectively, cause dyskeratosis congenita or Fanconi anaemia, two clinically related bone marrow failure syndromes. Mice expressing p53(Δ31), a mutant p53 lacking the C terminus, model dyskeratosis congenita. Accordingly, the increased p53 activity in p53(Δ31/Δ31) fibroblasts correlated with a decreased expression of 4 genes implicated in telomere syndromes. Here we show that these cells exhibit decreased mRNA levels for additional genes contributing to telomere metabolism, but also, surprisingly, for 12 genes mutated in Fanconi anaemia. Furthermore, p53(Δ31/Δ31) fibroblasts exhibit a reduced capacity to repair DNA interstrand crosslinks, a typical feature of Fanconi anaemia cells. Importantly, the p53-dependent downregulation of Fanc genes is largely conserved in human cells. Defective DNA repair is known to activate p53, but our results indicate that, conversely, an increased p53 activity may attenuate the Fanconi anaemia DNA repair pathway, defining a positive regulatory feedback loop.

Somatic Mutations and Ancestry Markers in Hispanic Lung Cancer Patients.

PubMed

Gimbrone, Nicholas T; Sarcar, Bhaswati; Gordian, Edna R; Rivera, Jason I; Lopez, Christian; Yoder, Sean J; Teer, Jamie K; Welsh, Eric A; Chiappori, Alberto A; Schabath, Matthew B; Reuther, Gary W; Dutil, Julie; Garcia, Miosotis; Ventosilla-Villanueva, Ronald; Vera-Valdivia, Luis; Yabar-Berrocal, Alejandro; Motta-Guerrero, Rodrigo; Santiago-Cardona, Pedro G; Muñoz-Antonia, Teresita; Cress, W Douglas

2017-12-01

To address the lack of genomic data from Hispanic/Latino (H/L) patients with lung cancer, the Latino Lung Cancer Registry was established to collect patient data and biospecimens from H/L patients. This retrospective observational study examined lung cancer tumor samples from 163 H/L patients, and tumor-derived DNA was subjected to targeted-exome sequencing (>1000 genes, including EGFR, KRAS, serine/threonine kinase 11 gene [STK11], and tumor protein p53 gene [TP53]) and ancestry analysis. Mutation frequencies in this H/L cohort were compared with those in a similar cohort of non-Hispanic white (NHW) patients and correlated with ancestry, sex, smoking status, and tumor histologic type. Of the adenocarcinomas in the H/L cohort (n = 120), 31% had EGFR mutations, versus 17% in the NHW control group (p < 0.001). KRAS (20% versus 38% [p = 0.002]) and STK11 (8% versus 16% [p = 0.065]) mutations occurred at lower frequency, and mutations in TP53 occurred at similar frequency (46% versus 40% [p = 0.355]) in H/L and NHW patients, respectively. Within the Hispanic cohort, ancestry influenced the rate of TP53 mutations (p = 0.009) and may have influenced the rate of EGFR, KRAS, and STK11 mutations. Driver mutations in H/L patients with lung adenocarcinoma differ in frequency from those in NHW patients associated with their indigenous American ancestry. The spectrum of driver mutations needs to be further assessed in the H/L population. Copyright © 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

PCR-RFLP to Detect Codon 248 Mutation in Exon 7 of "p53" Tumor Suppressor Gene

ERIC Educational Resources Information Center

Ouyang, Liming; Ge, Chongtao; Wu, Haizhen; Li, Suxia; Zhang, Huizhan

2009-01-01

Individual genome DNA was extracted fast from oral swab and followed up with PCR specific for codon 248 of "p53" tumor suppressor gene. "Msp"I restriction mapping showed the G-C mutation in codon 248, which closely relates to cancer susceptibility. Students learn the concepts, detection techniques, and research significance of point mutations or…

Two co-existing germline mutations P53 V157D and PMS2 R20Q promote tumorigenesis in a familial cancer syndrome.

PubMed

Wang, Zuoyun; Sun, Yihua; Gao, Bin; Lu, Yi; Fang, Rong; Gao, Yijun; Xiao, Tian; Liu, Xin-Yuan; Pao, William; Zhao, Yun; Chen, Haiquan; Ji, Hongbin

2014-01-01

Germline mutations are responsible for familial cancer syndromes which account for approximately 5-10% of all types of cancers. These mutations mainly occur at tumor suppressor genes or genome stability genes, such as DNA repair genes. Here we have identified a cancer predisposition family, in which eight members were inflicted with a wide spectrum of cancer including one diagnosed with lung cancer at 22years old. Sequencing analysis of tumor samples as well as histologically normal specimens identified two germline mutations co-existing in the familial cancer syndrome, the mutation of tumor suppressor gene P53 V157D and mismatch repair gene PMS2 R20Q. We further demonstrate that P53 V157D and/or PMS2 R20Q mutant promotes lung cancer cell proliferation. These two mutants are capable of promoting colony formation in soft agar as well as tumor formation in transgenic drosophila system. Collectively, these data have uncovered the important role of co-existing germline P53 and PMS2 mutations in the familial cancer syndrome development. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Two co-existing germline mutations P53 V157D and PMS2 R20Q promote tumorigenesis in a familial cancer syndrome

PubMed Central

Wang, Zuoyun; Sun, Yihua; Gao, Bin; Lu, Yi; Fang, Rong; Gao, Yijun; Xiao, Tian; Liu, Xin-Yuan; Pao, William; Zhao, Yun; Chen, Haiquan; Ji, Hongbin

2014-01-01

Germline mutations are responsible for familial cancer syndromes which account for approximately 5–10% of all types of cancers. These mutations mainly occur at tumor suppressor genes or genome stability genes, such as DNA repair genes. Here we have identified a cancer predisposition family, in which eight members were inflicted with a wide spectrum of cancer including one diagnosed with lung cancer at 22 years old. Sequencing analysis of tumor samples as well as histologically normal specimens identified two germline mutations co-existing in the familial cancer syndrome, the mutation of tumor suppressor gene P53 V157D and mismatch repair gene PMS2 R20Q. We further demonstrate that P53 V157D and/or PMS2 R20Q mutant promotes lung cancer cell proliferation. These two mutants are capable of promoting colony formation in soft agar as well as tumor formation in transgenic drosophila system. Collectively, these data have uncovered the important role of co-existing germline P53 and PMS2 mutations in the familial cancer syndrome development. PMID:23981578

The role of p53 in cancer drug resistance and targeted chemotherapy.

PubMed

Hientz, Karin; Mohr, André; Bhakta-Guha, Dipita; Efferth, Thomas

2017-01-31

Cancer has long been a grievous disease complicated by innumerable players aggravating its cure. Many clinical studies demonstrated the prognostic relevance of the tumor suppressor protein p53 for many human tumor types. Overexpression of mutated p53 with reduced or abolished function is often connected to resistance to standard medications, including cisplatin, alkylating agents (temozolomide), anthracyclines, (doxorubicin), antimetabolites (gemcitabine), antiestrogenes (tamoxifen) and EGFR-inhibitors (cetuximab). Such mutations in the TP53 gene are often accompanied by changes in the conformation of the p53 protein. Small molecules that restore the wild-type conformation of p53 and, consequently, rebuild its proper function have been identified. These promising agents include PRIMA-1, MIRA-1, and several derivatives of the thiosemicarbazone family. In addition to mutations in p53 itself, p53 activity may be also be impaired due to alterations in p53's regulating proteins such as MDM2. MDM2 functions as primary cellular p53 inhibitor and deregulation of the MDM2/p53-balance has serious consequences. MDM2 alterations often result in its overexpression and therefore promote inhibition of p53 activity. To deal with this problem, a judicious approach is to employ MDM2 inhibitors. Several promising MDM2 inhibitors have been described such as nutlins, benzodiazepinediones or spiro-oxindoles as well as novel compound classes such as xanthone derivatives and trisubstituted aminothiophenes. Furthermore, even naturally derived inhibitor compounds such as α-mangostin, gambogic acid and siladenoserinols have been discovered. In this review, we discuss in detail such small molecules that play a pertinent role in affecting the p53-MDM2 signaling axis and analyze their potential as cancer chemotherapeutics.

The genetic landscape of endometrial clear cell carcinomas.

PubMed

DeLair, Deborah F; Burke, Kathleen A; Selenica, Pier; Lim, Raymond S; Scott, Sasinya N; Middha, Sumit; Mohanty, Abhinita S; Cheng, Donavan T; Berger, Michael F; Soslow, Robert A; Weigelt, Britta

2017-10-01

Clear cell carcinoma of the endometrium is a rare type of endometrial cancer that is generally associated with an aggressive clinical behaviour. Here, we sought to define the repertoire of somatic genetic alterations in endometrial clear cell carcinomas (ECCs), and whether ECCs could be classified into the molecular subtypes described for endometrial endometrioid and serous carcinomas. We performed a rigorous histopathological review, immunohistochemical analysis and massively parallel sequencing targeting 300 cancer-related genes of 32 pure ECCs. Eleven (34%), seven (22%) and six (19%) ECCs showed abnormal expression patterns for p53, ARID1A, and at least one DNA mismatch repair (MMR) protein, respectively. Targeted sequencing data were obtained from 30 of the 32 ECCs included in this study, and these revealed that two ECCs (7%) were ultramutated and harboured mutations affecting the exonuclease domain of POLE. In POLE wild-type ECCs, TP53 (46%), PIK3CA (36%), PPP2R1A (36%), FBXW7 (25%), ARID1A (21%), PIK3R1 (18%) and SPOP (18%) were the genes most commonly affected by mutations; 18% and 11% harboured CCNE1 and ERBB2 amplifications, respectively, and 11% showed DAXX homozygous deletions. ECCs less frequently harboured mutations affecting CTNNB1 and PTEN but more frequently harboured PPP2R1A and TP53 mutations than non-POLE endometrioid carcinomas from The Cancer Genome Atlas (TCGA). Compared to endometrial serous carcinomas (TCGA), ECCs less frequently harboured TP53 mutations. When a surrogate model for the molecular-based TCGA classification was used, all molecular subtypes previously identified in endometrial endometrioid and serous carcinomas were present in the ECCs studied, including POLE, MMR-deficient, copy-number high (serous-like)/p53 abnormal, and copy-number low (endometrioid)/p53 wild-type, which were significantly associated with disease-free survival in univariate analysis. These findings demonstrate that ECCs constitute a histologically and genetically heterogeneous group of tumours with varying outcomes. Furthermore, our data suggest that the classification of ECCs as being generally 'high-grade' or 'type II' tumours may not be warranted. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Immunohistochemical detection of tumor suppressor gene p53 protein in feline injection site-associated sarcomas.

PubMed

Nambiar, P R; Jackson, M L; Ellis, J A; Chelack, B J; Kidney, B A; Haines, D M

2001-03-01

Sarcomas associated with injection sites are a rare but important problem in cats. Immunohistochemical detection of p53 protein may correlate to mutation of the p53 tumor suppressor gene, a gene known to be important in oncogenesis. The expression of nuclear p53 protein in 40 feline injection site-assocated sarcomas was examined by immunohistochemical staining. In 42.5% (17/40), tumor cell nuclei were stained darkly; in 20% (8/40), tumor cell nuclei were stained palely; and in 37.5% (15/40), tumor cell nuclei were unstained. Immunohistochemical detection of p53 protein in a proportion of injection site-associated sarcomas suggests that mutation of the p53 gene may play a role in the pathogenesis of these tumors.

Chromosome 17p Homodisomy Is Associated With Better Outcome in 1p19q Non-Codeleted and IDH-Mutated Gliomas

PubMed Central

Labussière, Marianne; Rahimian, Amithys; Giry, Marine; Boisselier, Blandine; Schmitt, Yohann; Polivka, Marc; Mokhtari, Karima; Delattre, Jean-Yves; Idbaih, Ahmed; Alentorn, Agusti

2016-01-01

Background. The 1p19q non-codeleted gliomas with IDH mutation, defined as “molecular astrocytomas,” display frequent TP53 mutations and have an intermediate prognosis. We investigated the prognostic impact of copy number-neutral loss of heterozygosity (CNLOH) in 17p in this population. Methods. We analyzed 793 gliomas (206 grade II, 377 grade III, and 210 grade IV) by single nucleotide polymorphism array and for TP53 mutations. Results. Homodisomy revealed by CNLOH was observed in 156 cases (19.7%). It was more frequent in astrocytomas and oligoastrocytomas (98/256, 38%) than oligodendrogliomas (28/327, 8.6%; p < .0001) or glioblastoma multiforme (30/210, 14.3%; p < .0001), tightly associated with TP53 mutation (69/71 vs. 20/79; p = 2 × 10−16), and mutually exclusive with 1p19q codeletion (1/156 vs. 249/556; p < .0001). In the group of IDH-mutated 1p19q non-codeleted gliomas, CNLOH 17p was associated with longer survival (86.3 vs. 46.2 months; p = .004), particularly in grade III gliomas (overall survival >100 vs. 37.9 months; p = .007). These data were confirmed in an independent dataset from the Cancer Genome Atlas. Conclusion. CNLOH 17p is a prognostic marker and further refines the molecular classification of gliomas. Implications for Practice: Homodisomy of chromosome 17p (CNLOH 17p) is a frequent feature in IDH-mutated 1p19q non-codeleted gliomas (group 2). It is constantly associated with TP53 mutation. It was found, within this specific molecular group of gliomas (corresponding to molecular astrocytomas), that CNLOH 17p is associated with a much better outcome and may therefore represent an additional prognostic marker to refine the prognostic classification of gliomas. PMID:27401888

Low-burden TP53 mutations in chronic phase of myeloproliferative neoplasms: association with age, hydroxyurea administration, disease type and JAK2 mutational status

PubMed Central

Kubesova, B; Pavlova, S; Malcikova, J; Kabathova, J; Radova, L; Tom, N; Tichy, B; Plevova, K; Kantorova, B; Fiedorova, K; Slavikova, M; Bystry, V; Kissova, J; Gisslinger, B; Gisslinger, H; Penka, M; Mayer, J; Kralovics, R; Pospisilova, S; Doubek, M

2018-01-01

The multistep process of TP53 mutation expansion during myeloproliferative neoplasm (MPN) transformation into acute myeloid leukemia (AML) has been documented retrospectively. It is currently unknown how common TP53 mutations with low variant allele frequency (VAF) are, whether they are linked to hydroxyurea (HU) cytoreduction, and what disease progression risk they carry. Using ultra-deep next-generation sequencing, we examined 254 MPN patients treated with HU, interferon alpha-2a or anagrelide and 85 untreated patients. We found TP53 mutations in 50 cases (0.2–16.3% VAF), regardless of disease subtype, driver gene status and cytoreduction. Both therapy and TP53 mutations were strongly associated with older age. Over-time analysis showed that the mutations may be undetectable at diagnosis and slowly increase during disease course. Although three patients with TP53 mutations progressed to TP53-mutated or TP53-wild-type AML, we did not observe a significant age-independent impact on overall survival during the follow-up. Further, we showed that complete p53 inactivation alone led to neither blast transformation nor HU resistance. Altogether, we revealed patient's age as the strongest factor affecting low-burden TP53 mutation incidence in MPN and found no significant age-independent association between TP53 mutations and hydroxyurea. Mutations may persist at low levels for years without an immediate risk of progression. PMID:28744014

Activation of PTHrP-cAMP-CREB1 signaling following p53 loss is essential for osteosarcoma initiation and maintenance.

PubMed

Walia, Mannu K; Ho, Patricia Mw; Taylor, Scott; Ng, Alvin Jm; Gupte, Ankita; Chalk, Alistair M; Zannettino, Andrew Cw; Martin, T John; Walkley, Carl R

2016-04-12

Mutations in the P53 pathway are a hallmark of human cancer. The identification of pathways upon which p53-deficient cells depend could reveal therapeutic targets that may spare normal cells with intact p53. In contrast to P53 point mutations in other cancer, complete loss of P53 is a frequent event in osteosarcoma (OS), the most common cancer of bone. The consequences of p53 loss for osteoblastic cells and OS development are poorly understood. Here we use murine OS models to demonstrate that elevated Pthlh (Pthrp), cAMP levels and signalling via CREB1 are characteristic of both p53-deficient osteoblasts and OS. Normal osteoblasts survive depletion of both PTHrP and CREB1. In contrast, p53-deficient osteoblasts and OS depend upon continuous activation of this pathway and undergo proliferation arrest and apoptosis in the absence of PTHrP or CREB1. Our results identify the PTHrP-cAMP-CREB1 axis as an attractive pathway for therapeutic inhibition in OS.

The Inherited p53 Mutation in the Brazilian Population.

PubMed

Achatz, Maria Isabel; Zambetti, Gerard P

2016-12-01

A common criticism of studying rare diseases is the often-limited relevance of the findings to human health. Here, we review ∼15 years of research into an unusual germline TP53 mutation (p.R337H) that began with its detection in children with adrenocortical carcinoma (ACC), a remarkably rare childhood cancer that is associated with poor prognosis. We have come to learn that the p.R337H mutation exists at a very high frequency in Southern and Southeastern Brazil, occurring in one of 375 individuals within a total population of ∼100 million. Moreover, it has been determined that carriers of this founder mutation display variable tumor susceptibility, ranging from isolated cases of pediatric ACC to Li-Fraumeni or Li-Fraumeni-like (LFL) syndromes, thus representing a significant medical issue for this country. Studying the biochemical and molecular consequences of this mutation on p53 tumor-suppressor activity, as well as the putative additional genetic alterations that cooperate with this mutation, is advancing our understanding of how p53 functions in tumor suppression in general. These studies, which originated with a rare childhood tumor, are providing important information for guiding genetic counselors and physicians in treating their patients and are already providing clinical benefit. Copyright © 2016 Cold Spring Harbor Laboratory Press; all rights reserved.

BRCA1/2 and TP53 mutation status associates with PD-1 and PD-L1 expression in ovarian cancer.

PubMed

Wieser, Verena; Gaugg, Inge; Fleischer, Martina; Shivalingaiah, Giridhar; Wenzel, Soeren; Sprung, Susanne; Lax, Sigurd F; Zeimet, Alain G; Fiegl, Heidelinde; Marth, Christian

2018-04-03

Checkpoint molecules such as programmed cell death protein-1 (PD-1) and its ligand PD-L1 are critically required for tumor immune escape. The objective of this study was to investigate tumoral PD-1 and PD-L1 mRNA-expression in a cohort of ovarian cancer (OC) patients in relation to tumor mutations. We analyzed mRNA expression of PD-1 , PD-L1 and IFNG by quantitative real-time PCR in tissue of 170 patients with low grade-serous (LGSOC), high-grade serous (HGSOC), endometrioid and clear cell OC compared to 28 non-diseased tissues (ovaries and fallopian tubes) in relation to tumor protein 53 ( TP53 ) and breast cancer gene 1/2 ( BRCA1/2 ) mutation status. TP53 -mutated OC strongly expressed PD-L1 compared to TP53 wild-type OC ( p = 0.028) and BRCA1/2 -mutated OC increasingly expressed PD-1 ( p = 0.024) and PD-L1 ( p = 0.012) compared to BRCA1/2 wild-type OC. For the first time in human, we noted a strong correlation between tumoral IFNG and PD-1 or PD-L1 mRNA-expression, respectively ( p < 0.001). OC tissue increasingly expressed PD-1 compared to healthy controls (vs. ovaries: p < 0.001; vs. tubes: p = 0.018). PD-1 and PD-L1 mRNA-expression increased with higher tumor grade ( p = 0.008 and p = 0.027, respectively) and younger age (< median age, p = 0.001). Finally, in the major subgroup of our cohort, FIGO stage III/IV HGSOC, high PD-1 and PD-L1 mRNA-expression was associated with reduced progression-free ( p = 0.024) and overall survival ( p = 0.049) but only in the univariate analysis. Our study suggests that in OC PD-1 / PD-L1 mRNA-expression is controlled by IFNγ and affected by TP53 and BRCA1/2 mutations. We suggest that these mutations might serve as potential predictive factors that guide anti- PD1 / PD-L1 immunotherapy.

Inhibition of p53 Mutant Peptide Aggregation In Vitro by Cationic Osmolyte Acetylcholine Chloride.

PubMed

Chen, Zhaolin; Kanapathipillai, Mathumai

2017-01-01

Mutations of tumor suppressor protein p53 are present in almost about 50% of all cancers. It has been reported that the p53 mutations cause aggregation and subsequent loss of p53 function, leading to cancer progression. Here in this study we focus on the inhibitory effects of cationic osmolyte molecules acetylcholine chloride, and choline on an aggregation prone 10 amino acid p53 mutant peptide WRPILTIITL, and the corresponding wildtype peptide RRPILTIITL in vitro. The characterization tools used for this study include Thioflavin- T (ThT) induced fluorescence, transmission electron microscopy (TEM), congo red binding, turbidity, dynamic light scattering (DLS), and cell viability assays. The results show that acetylcholine chloride in micromolar concentrations significantly inhibit p53 mutant peptide aggregation in vitro, and could be promising candidate for p53 mutant/ misfolded protein aggregation inhibition. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Evidence that expression of a mutated p53 gene attenuates apoptotic cell death in human gastric intestinal-type carcinomas in vivo.

PubMed

Ishida, M; Gomyo, Y; Ohfuji, S; Ikeda, M; Kawasaki, H; Ito, H

1997-05-01

To examine in vivo the validity of the results of experiments in vitro, we analyzed the relationship between p53 gene status and apoptotic cell death of human gastric intestinal-type adenocarcinomas. Surgical specimens were classified into two categories: 18 gastric cancers with nuclear p53 protein (A), and 17 gastric cancers without nuclear p53 protein (B). Polymerase chain reaction-single strand conformation polymorphism disclosed a shifted band that corresponded to a mutation in the p53 gene in 13 cases (72%) in category A and 3 cases (18%) in category B, the frequency being significantly higher in the former (P < 0.05). Apoptotic cells were identified from routinely stained sections and by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The TUNEL index [TI; (the number of TUNEL-positive apoptotic cells/the total number of tumor cells) x 100] was 3.8 +/- 1.4% in category A and 4.9 +/- 1.2% in category B, the value being significantly lower in the former (P < 0.05). The proliferating cell nuclear antigen index, defined similarly to the TI, was 56.4 +/- 16.3% in category A, and it was significantly higher than that in category B (P < 0.05). The immunohistochemically detected expression of p21CIP1/WAP1 did not differ between the two categories, while Bax-positive tumor cells were more frequently detected in category A. These results indicate that (1) expression of a mutated p53 gene attenuates apoptotic cell death of gastric cancer, in accordance with the previous in vitro finding that p53 gene mutation provides a possible selective advantage for tumor cell proliferation, and (2) apoptosis is related not only to expression of p53 and the stage of the cell cycle, but also to p53-independent and cell cycle-independent events.

MDM4 is a key therapeutic target in cutaneous melanoma

PubMed Central

Gembarska, Agnieszka; Luciani, Flavie; Fedele, Clare; Russell, Elisabeth A; Dewaele, Michael; Villar, Stéphanie; Zwolinska, Aleksandra; Haupt, Sue; de Lange, Job; Yip, Dana; Goydos, James; Haigh, Jody J; Haupt, Ygal; Larue, Lionel; Jochemsen, Aart; Shi, Hubing; Moriceau, Gatien; Lo, Roger S; Ghanem, Ghanem; Shackleton, Mark; Bernal, Federico; Marine, Jean-Christophe

2013-01-01

The inactivation of the p53 tumor suppressor pathway, which often occurs through mutations in TP53 (encoding tumor protein 53) is a common step in human cancer. However, in melanoma—a highly chemotherapy-resistant disease—TP53 mutations are rare, raising the possibility that this cancer uses alternative ways to overcome p53-mediated tumor suppression. Here we show that Mdm4 p53 binding protein homolog (MDM4), a negative regulator of p53, is upregulated in a substantial proportion (∼65%) of stage I–IV human melanomas and that melanocyte-specific Mdm4 overexpression enhanced tumorigenesis in a mouse model of melanoma induced by the oncogene Nras. MDM4 promotes the survival of human metastatic melanoma by antagonizing p53 proapoptotic function. Notably, inhibition of the MDM4-p53 interaction restored p53 function in melanoma cells, resulting in increased sensitivity to cytotoxic chemotherapy and to inhibitors of the BRAF (V600E) oncogene. Our results identify MDM4 as a key determinant of impaired p53 function in human melanoma and designate MDM4 as a promising target for antimelanoma combination therapy. PMID:22820643

Activating mutations for transformation by p53 produce a gene product that forms an hsc70-p53 complex with an altered half-life

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

Finlay, C.A.; Hinds, P.W.; Tan, T.H.

1988-02-01

The 11-4 p53 cDNA clone failed to transform primary rat fibroblasts when cotransfected with the ras oncogene. Two linker insertion mutations at amino acid 158 or 215 (of 390 amino acids) activated this p53 cDNA for transformation with ras. These mutant cDNAs produced a p53 protein that lacked an epitope, recognized by monoclonal antibody PAb246 (localized at amino acids 88 to 110 in the protein) and preferentially bound to a heat shock protein, hsc70. In rat cells transformed by a genomic p53 clone plus ras, two populations of p53 proteins were detected, PAb246/sup +/ and PAb246/sup -/, which did ormore » did not bind to this monoclonal antibody, respectively. The PAb246/sup -/ p53 preferentially associated with hsc70, and this protein has a half-life 4- to 20-fold longer than free p53 (PAb246/sup +/). These data suggest a possible functional role for hsc70 in the transformation process. cDNAs for p53 derived from methylcholanthrene-transformed cells transform rat cells in cooperation with the ras oncogene and produce a protein that bound with the heat shock proteins. Recombinant clones produced between a Meth A cDNA and 11-4 were tested for the ability to transform rat cells. A single amino acid substitution at residue 132 was sufficient to activate the 11-4 p53 cDNA for transformation. These studies have identified a region between amino acids 132 and 215 in the p53 protein which, when mutated, can activate the p53 cDNA. These results also call into question what the correct p53 wild-type sequence is and whether a wild-type p53 gene can transform cells in culture.« less

MicroRNA-145 is regulated by DNA methylation and p53 gene mutation in prostate cancer

PubMed Central

Suh, Seong O.; Chen, Yi; Zaman, Mohd Saif; Hirata, Hiroshi; Yamamura, Soichiro; Shahryari, Varahram; Liu, Jan; Tabatabai, Z.Laura; Kakar, Sanjay; Deng, Guoren; Tanaka, Yuichiro; Dahiya, Rajvir

2011-01-01

MiR-145 is downregulated in various cancers including prostate cancer. However, the underlying mechanisms of miR-145 downregulation are not fully understood. Here, we reported that miR-145 was silenced through DNA hypermethylation and p53 mutation status in laser capture microdissected (LCM) prostate cancer and matched adjacent normal tissues. In 22 of 27 (81%) prostate tissues, miR-145 was significantly downregulated in the cancer compared with the normal tissues. Further studies on miR-145 downregulation mechanism showed that miR-145 is methylated at the promoter region in both prostate cancer tissues and 50 different types of cancer cell lines. In seven cancer cell lines with miR-145 hypermethylation, 5-aza-2′-deoxycytidine treatment dramatically induced miR-145 expression. Interestingly, we also found a significant correlation between miR-145 expression and the status of p53 gene in both LCM prostate tissues and 47 cancer cell lines. In 29 cell lines with mutant p53, miR-145 levels were downregulated in 28 lines (97%), whereas in 18 cell lines with wild-type p53 (WT p53), miR-145 levels were downregulated in only 6 lines (33%, P < 0.001). Electrophoretic mobility shift assay showed that p53 binds to the p53 response element upstream of miR-145, but the binding was inhibited by hypermethylation. To further confirm that p53 binding to miR-145 could regulate miR-145 expression, we transfected WT p53 and MUT p53 into PC-3 cells and found that miR-145 is upregulated by WT p53 but not with MUTp53. The apoptotic cells are increased after WT p53 transfection. In summary, this is the first report documenting that downregulation of miR-145 is through DNA methylation and p53 mutation pathways in prostate cancer. PMID:21349819

p53 Mutation suppresses adult neurogenesis in medaka fish (Oryzias latipes)

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

Isoe, Yasuko; Okuyama, Teruhiro; Taniguchi, Yoshihito

2012-07-13

Highlights: Black-Right-Pointing-Pointer Progenitor migration is accompanied by an increase in their numbers in the adult brain. Black-Right-Pointing-Pointer p53 Mutation suppressed an increase in the number of the migrated progenitors. Black-Right-Pointing-Pointer The decreased progenitor number is not due to enhanced cell death. Black-Right-Pointing-Pointer p53 Mutation did not affect proliferation of stem cells. -- Abstract: Tumor suppressor p53 negatively regulates self-renewal of neural stem cells in the adult murine brain. Here, we report that the p53 null mutation in medaka fish (Oryzias latipes) suppressed neurogenesis in the telencephalon, independent of cell death. By using 5-bromo-29-deoxyuridine (BrdU) immunohistochemistry, we identified 18 proliferation zonesmore » in the brains of young medaka fish; in situ hybridization showed that p53 was expressed selectively in at least 12 proliferation zones. We also compared the number of BrdU-positive cells present in the whole telencephalon of wild-type (WT) and p53 mutant fish. Immediately after BrdU exposure, the number of BrdU-positive cells did not differ significantly between them. One week after BrdU-exposure, the BrdU-positive cells migrated from the proliferation zone, which was accompanied by an increased number in the WT brain. In contrast, no significant increase was observed in the p53 mutant brain. Terminal deoxynucleotidyl transferase (dUTP) nick end-labeling revealed that there was no significant difference in the number of apoptotic cells in the telencephalon of p53 mutant and WT medaka, suggesting that the decreased number of BrdU-positive cells in the mutant may be due to the suppression of proliferation rather than the enhancement of neural cell death. These results suggest that p53 positively regulates neurogenesis via cell proliferation.« less

Enrofloxacin enhances the effects of chemotherapy in canine osteosarcoma cells with mutant and wild-type p53

PubMed Central

York, D.; Withers, S. S.; Watson, K. D.; Seo, K. W.; Rebhun, R. B.

2016-01-01

Adjuvant chemotherapy improves survival time in dogs receiving adequate local control for appendicular osteosarcoma, but most dogs ultimately succumb to metastatic disease. The fluoroquinolone antibiotic enrofloxacin has been shown to inhibit survival and proliferation of canine osteosarcoma cells in vitro. Others have reported that fluoroquinolones may modulate cellular responses to DNA damaging agents and that these effects may be differentially mediated by p53 activity. We therefore determined p53 status and activity in three canine osteosarcoma cell lines and examined the effects of enrofloxacin when used alone or in combination with doxorubicin or carboplatin chemotherapy. Moresco and Abrams canine osteosarcoma cell lines contained mutations in p53, while no mutations were identified in the D17 cells or in a normal canine osteoblast cell line. The addition of enrofloxacin to either doxorubicin or carboplatin resulted in further reductions in osteosarcoma cell viability; this effect was apparent regardless of p53 mutational status or downstream activity. PMID:27333821

Enrofloxacin enhances the effects of chemotherapy in canine osteosarcoma cells with mutant and wild-type p53.

PubMed

York, D; Withers, S S; Watson, K D; Seo, K W; Rebhun, R B

2017-09-01

Adjuvant chemotherapy improves survival time in dogs receiving adequate local control for appendicular osteosarcoma, but most dogs ultimately succumb to metastatic disease. The fluoroquinolone antibiotic enrofloxacin has been shown to inhibit survival and proliferation of canine osteosarcoma cells in vitro. Others have reported that fluoroquinolones may modulate cellular responses to DNA damaging agents and that these effects may be differentially mediated by p53 activity. We therefore determined p53 status and activity in three canine osteosarcoma cell lines and examined the effects of enrofloxacin when used alone or in combination with doxorubicin or carboplatin chemotherapy. Moresco and Abrams canine osteosarcoma cell lines contained mutations in p53, while no mutations were identified in the D17 cells or in a normal canine osteoblast cell line. The addition of enrofloxacin to either doxorubicin or carboplatin resulted in further reductions in osteosarcoma cell viability; this effect was apparent regardless of p53 mutational status or downstream activity. © 2016 John Wiley & Sons Ltd.

249 TP53 mutation has high prevalence and is correlated with larger and poorly differentiated HCC in Brazilian patients.

PubMed

Nogueira, Jeronimo A; Ono-Nita, Suzane K; Nita, Marcelo E; de Souza, Marcelo M T; do Carmo, Eliane P; Mello, Evandro S; Scapulatempo, Cristovan; Paranaguá-Vezozzo, Denise C; Carrilho, Flair J; Alves, Venancio A F

2009-06-26

Ser-249 TP53 mutation (249(Ser)) is a molecular evidence for aflatoxin-related carcinogenesis in Hepatocellular Carcinoma (HCC) and it is frequent in some African and Asian regions, but it is unusual in Western countries. HBV has been claimed to add a synergic effect on genesis of this particular mutation with aflatoxin. The aim of this study was to investigate the frequency of 249(Ser) mutation in HCC from patients in Brazil. We studied 74 HCC formalin fixed paraffin blocks samples of patients whom underwent surgical resection in Brazil. 249(Ser) mutation was analyzed by RFLP and DNA sequencing. HBV DNA presence was determined by Real-Time PCR. 249(Ser) mutation was found in 21/74 (28%) samples while HBV DNA was detected in 13/74 (16%). 249Ser mutation was detected in 21/74 samples by RFLP assay, of which 14 were confirmed by 249(Ser) mutant-specific PCR, and 12 by nucleic acid sequencing. All HCC cases with p53-249ser mutation displayed also wild-type p53 sequences. Poorly differentiated HCC was more likely to have 249(Ser) mutation (OR = 2.415, 95% CI = 1.001 - 5.824, p = 0.05). The mean size of 249(Ser) HCC tumor was 9.4 cm versus 5.5 cm on wild type HCC (p = 0.012). HBV DNA detection was not related to 249(Ser) mutation. Our results indicate that 249(Ser) mutation is a HCC important factor of carcinogenesis in Brazil and it is associated to large and poorly differentiated tumors.

Significance of TP53 Mutation in Wilms Tumors with Diffuse Anaplasia: A Report from the Children's Oncology Group.

PubMed

Ooms, Ariadne H A G; Gadd, Samantha; Gerhard, Daniela S; Smith, Malcolm A; Guidry Auvil, Jaime M; Meerzaman, Daoud; Chen, Qing-Rong; Hsu, Chih Hao; Yan, Chunhua; Nguyen, Cu; Hu, Ying; Ma, Yussanne; Zong, Zusheng; Mungall, Andrew J; Moore, Richard A; Marra, Marco A; Huff, Vicki; Dome, Jeffrey S; Chi, Yueh-Yun; Tian, Jing; Geller, James I; Mullighan, Charles G; Ma, Jing; Wheeler, David A; Hampton, Oliver A; Walz, Amy L; van den Heuvel-Eibrink, Marry M; de Krijger, Ronald R; Ross, Nicole; Gastier-Foster, Julie M; Perlman, Elizabeth J

2016-11-15

To investigate the role and significance of TP53 mutation in diffusely anaplastic Wilms tumors (DAWTs). All DAWTs registered on National Wilms Tumor Study-5 (n = 118) with available samples were analyzed for TP53 mutations and copy loss. Integrative genomic analysis was performed on 39 selected DAWTs. Following analysis of a single random sample, 57 DAWTs (48%) demonstrated TP53 mutations, 13 (11%) copy loss without mutation, and 48 (41%) lacked both [defined as TP53-wild-type (wt)]. Patients with stage III/IV TP53-wt DAWTs (but not those with stage I/II disease) had significantly lower relapse and death rates than those with TP53 abnormalities. In-depth analysis of a subset of 39 DAWTs showed seven (18%) to be TP53-wt: These demonstrated gene expression evidence of an active p53 pathway. Retrospective pathology review of TP53-wt DAWT revealed no or very low volume of anaplasia in six of seven tumors. When samples from TP53-wt tumors known to contain anaplasia histologically were available, abnormal p53 protein accumulation was observed by immunohistochemistry. These data support the key role of TP53 loss in the development of anaplasia in WT, and support its significant clinical impact in patients with residual anaplastic tumor following surgery. These data also suggest that most DAWTs will show evidence of TP53 mutation when samples selected for the presence of anaplasia are analyzed. This suggests that modifications of the current criteria to also consider volume of anaplasia and documentation of TP53 aberrations may better reflect the risk of relapse and death and enable optimization of therapeutic stratification. Clin Cancer Res; 22(22); 5582-91. ©2016 AACR. ©2016 American Association for Cancer Research.

Significance of TP53 Mutation in Wilms Tumors with Diffuse Anaplasia: A Report from the Children’s Oncology Group

PubMed Central

Ooms, Ariadne H.A.G.; Gadd, Samantha; Gerhard, Daniela S.; Smith, Malcolm A.; Guidry Auvil, Jaime M.; Meerzaman, Daoud; Chen, Qing-Rong; Hsu, Chih Hao; Yan, Chunhua; Nguyen, Cu; Hu, Ying; Ma, Yussanne; Zong, Zusheng; Mungall, Andrew J.; Moore, Richard A.; Marra, Marco A.; Huff, Vicki; Dome, Jeffrey S.; Chi, Yueh-Yun; Tian, Jing; Geller, James I.; Mullighan, Charles G.; Ma, Jing; Wheeler, David A.; Hampton, Oliver A.; Walz, Amy L.; van den Heuvel-Eibrink, Marry M.; de Krijger, Ronald R.; Ross, Nicole; Gastier-Foster, Julie M.; Perlman, Elizabeth J.

2016-01-01

Purpose To investigate the role and significance of TP53 mutation in diffusely anaplastic Wilms tumor (DAWT). Experimental Design All DAWTs registered on National Wilms Tumor Study-5 (n=118) with available samples were analyzed for TP53 mutations and copy loss. Integrative genomic analysis was performed on 39 selected DAWTs. Results Following analysis of a single random sample, 57 DAWT (48%) demonstrated TP53 mutations, 13(11%) copy loss without mutation, and 48(41%) lacked both (defined as TP53-wildtype (wt)). Patients with Stage III/IV TP53-wt DAWTs (but not those with Stage I/II disease) had significantly lower relapse and death rates than those with TP53 abnormalities. In-depth analysis of a subset of 39 DAWT showed 7(18%) to be TP53-wt: these demonstrated gene expression evidence of an active p53 pathway. Retrospective pathology review of TP53-wt DAWT revealed no or very low volume of anaplasia in 6/7 tumors. When samples from TP53-wt tumors known to contain anaplasia histologically were available, abnormal p53 protein accumulation was observed by immunohistochemistry. Conclusion These data support the key role of TP53 loss in the development of anaplasia in WT, and support its significant clinical impact in patients with residual anaplastic tumor following surgery. These data also suggest that most DAWTs will show evidence of TP53 mutation when samples selected for the presence of anaplasia are analyzed. This suggests that modifications of the current criteria to also consider volume of anaplasia and documentation of TP53 aberrations may better reflect the risk of relapse and death and enable optimization of therapeutic stratification. PMID:27702824

The Role of p53 in Combination Radioimmunotherapy with 64Cu-DOTA-Cetuximab and Cisplatin in a Mouse Model of Colorectal Cancer

PubMed Central

Guo, Yunjun; Parry, Jesse J.; Laforest, Richard; Rogers, Buck E.; Anderson, Carolyn J.

2014-01-01

Radioimmunotherapy has been successfully used in the treatment of lymphoma but thus far has not demonstrated significant efficacy in humans beyond disease stabilization in solid tumors. Radioimmunotherapy with 64Cu was highly effective in a hamster model of colorectal cancer, but targeted radiotherapies with this radionuclide have since not shown as much success. It is widely known that mutations in key proteins play a role in the success or failure of cancer therapies. For example, the KRAS mutation is predictive of poor response to anti–epidermal growth factor receptor therapies in colorectal cancer, whereas p53 is frequently mutated in tumors, causing resistance to multiple therapeutic regimens. Methods We previously showed that nuclear localization of 64Cu-labeled DOTA-cetuximab was enhanced in p53 wild-type tumor cells. Here, we examine the role of p53 in the response to radioimmunotherapy with 64Cu-DOTA-cetuximab in KRAS-mutated HCT116 tumor–bearing mice, with and without cisplatin, which upregulates wild-type p53. Results Experiments with HCT116 cells that are p53 +/+ (p53 wild-type) and −/− (p53 null) grown in cell culture demonstrated that preincubation with cisplatin increased expression of p53 and subsequently enhanced localization of 64Cu from 64Cuacetate and 64Cu-DOTA-cetuximab to the tumor cell nuclei. Radioimmunotherapy studies in p53-positive HCT116 tumor–bearing mice, receiving either radioimmunotherapy alone or in combination with cisplatin, showed significantly longer survival in mice receiving unlabeled cetuximab or cisplatin alone or in combination (all, P < 0.01). In contrast, the p53-negative tumor-bearing mice treated with radioimmunotherapy alone or combined with cisplatin showed no survival advantage, compared with control groups (all, P > 0.05). Conclusion Together, these data suggest that 64Cu specifically delivered to epidermal growth factor receptor–positive tumors by cetuximab can suppress tumor growth despite the KRAS status and present opportunities for personalized clinical treatment strategies in colorectal cancer. PMID:23873478

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

Drug resistance to inhibitors of the human double minute-2 E3 ligase is mediated by point mutations of p53, but can be overcome with the p53 targeting agent RITA.

PubMed

Jones, Richard J; Bjorklund, Chad C; Baladandayuthapani, Veerabhadran; Kuhn, Deborah J; Orlowski, Robert Z

2012-10-01

The human double minute (HDM)-2 E3 ubiquitin ligase plays a key role in p53 turnover and has been validated preclinically as a target in multiple myeloma (MM) and mantle cell lymphoma (MCL). HDM-2 inhibitors are entering clinical trials, and we therefore sought to understand potential mechanisms of resistance in lymphoid models. Wild-type p53 H929 MM and Granta-519 MCL cells resistant to MI-63 or Nutlin were generated by exposing them to increasing drug concentrations. MI-63-resistant H929 and Granta-519 cells were resistant to Nutlin, whereas Nutlin-resistant cells displayed cross-resistance to MI-63. These cells also showed cross-resistance to bortezomib, doxorubicin, cisplatin, and melphalan, but remained sensitive to the small molecule inhibitor RITA (reactivation of p53 and induction of tumor cell apoptosis). HDM-2 inhibitor-resistant cells harbored increased p53 levels, but neither genotoxic nor nongenotoxic approaches to activate p53 induced HDM-2 or p21. Resequencing revealed wild-type HDM-2, but mutations were found in the p53 DNA binding and dimerization domains. In resistant cells, RITA induced a G(2)-M arrest, upregulation of p53 targets HDM-2, PUMA, and NOXA, and PARP cleavage. Combination regimens with RITA and MI-63 resulted in enhanced cell death compared with RITA alone. These findings support the possibility that p53 mutation could be a primary mechanism of acquired resistance to HDM-2 inhibitors in MCL and MM. Furthermore, they suggest that simultaneous restoration of p53 function and HDM-2 inhibition is a rational strategy for clinical translation.

A homozygous p53 R282W mutant human embryonic stem cell line generated using TALEN-mediated precise gene editing.

PubMed

Zhou, Ruoji; Xu, An; Wang, Donghui; Zhu, Dandan; Mata, Helen; Huo, Zijun; Tu, Jian; Liu, Mo; Mohamed, Alaa M T; Jewell, Brittany E; Gingold, Julian; Xia, Weiya; Rao, Pulivarthi H; Hung, Mien-Chie; Zhao, Ruiying; Lee, Dung-Fang

2018-03-01

The tumor suppressor gene TP53 is the most frequently mutated gene in human cancers. Many hot-spot mutations of TP53 confer novel functions not found in wild-type p53 and contribute to tumor development and progression. We report on the generation of a H1 human embryonic stem cell line carrying a homozygous TP53 R282W mutation using TALEN-mediated genome editing. The generated cell line demonstrates normal karyotype, maintains a pluripotent state, and is capable of generating a teratoma in vivo containing tissues from all three germ layers. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

Avoiding restorative proctocolectomy for colorectal cancer in patients with ulcerative colitis based on preoperative diagnosis involving p53 immunostaining: report of a case.

PubMed

Sada, Haruki; Shimomura, Manabu; Hinoi, Takao; Egi, Hiroyuki; Kawaguchi, Koji; Yano, Takuya; Niitsu, Hiroaki; Saitou, Yasufumi; Sawada, Hiroyuki; Miguchi, Masashi; Adachi, Tomohiro; Ohdan, Hideki

2015-03-26

The standard operation for colitic cancer in ulcerative colitis (UC) is restorative proctocolectomy; however, sporadic colorectal cancer (CRC) can coincidentally arise in patients with UC and the optimal procedure remains controversial. Therefore, it is crucial to preoperatively determine whether the CRC in UC is a sporadic or colitic cancer. We report a case of avoiding proctocolectomy for sporadic CRC in a patient with UC based on preoperative diagnosis involving p53 immunostaining. A 73-year-old man with CRC in UC had undergone sigmoid colectomy with lymphadenectomy because of the submucosal deep invasion pathologically after endoscopic mucosal resection. The cancer was diagnosed sporadic cancer preoperatively not only based on the endoscopic, clinical, and histological patterns but also that the colon epithelium was unlikely to develop dysplasia as the circumference and unaffected UC mucosa did not detect p53 protein overexpression. Recent reports have shown that the immunohistochemical detection of p53 protein overexpression can be useful for a differential diagnosis and as a predictor of dysplasia and colitic cancer. The analysis of p53 mutation status based on immunostaining of p53 protein expression in the unaffected UC mucosa can be useful for the decision regarding a surgical procedure for CRC in patients with UC.

Molecular Regulation of DNA Damage-Induced Apoptosis in Neurons of Cerebral Cortex

PubMed Central

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

2009-01-01

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

Revealing determinants of two-phase dynamics of P53 network under gamma irradiation based on a reduced 2D relaxation oscillator model.

PubMed

Demirkıran, Gökhan; Kalaycı Demir, Güleser; Güzeliş, Cüneyt

2018-02-01

This study proposes a two-dimensional (2D) oscillator model of p53 network, which is derived via reducing the multidimensional two-phase dynamics model into a model of ataxia telangiectasia mutated (ATM) and Wip1 variables, and studies the impact of p53-regulators on cell fate decision. First, the authors identify a 6D core oscillator module, then reduce this module into a 2D oscillator model while preserving the qualitative behaviours. The introduced 2D model is shown to be an excitable relaxation oscillator. This oscillator provides a mechanism that leads diverse modes underpinning cell fate, each corresponding to a cell state. To investigate the effects of p53 inhibitors and the intrinsic time delay of Wip1 on the characteristics of oscillations, they introduce also a delay differential equation version of the 2D oscillator. They observe that the suppression of p53 inhibitors decreases the amplitudes of p53 oscillation, though the suppression increases the sustained level of p53. They identify Wip1 and P53DINP1 as possible targets for cancer therapies considering their impact on the oscillator, supported by biological findings. They model some mutations as critical changes of the phase space characteristics. Possible cancer therapeutic strategies are then proposed for preventing these mutations' effects using the phase space approach.

Comprehensive, Integrative Genomic Analysis of Diffuse Lower-Grade Gliomas.

PubMed

Brat, Daniel J; Verhaak, Roel G W; Aldape, Kenneth D; Yung, W K Alfred; Salama, Sofie R; Cooper, Lee A D; Rheinbay, Esther; Miller, C Ryan; Vitucci, Mark; Morozova, Olena; Robertson, A Gordon; Noushmehr, Houtan; Laird, Peter W; Cherniack, Andrew D; Akbani, Rehan; Huse, Jason T; Ciriello, Giovanni; Poisson, Laila M; Barnholtz-Sloan, Jill S; Berger, Mitchel S; Brennan, Cameron; Colen, Rivka R; Colman, Howard; Flanders, Adam E; Giannini, Caterina; Grifford, Mia; Iavarone, Antonio; Jain, Rajan; Joseph, Isaac; Kim, Jaegil; Kasaian, Katayoon; Mikkelsen, Tom; Murray, Bradley A; O'Neill, Brian Patrick; Pachter, Lior; Parsons, Donald W; Sougnez, Carrie; Sulman, Erik P; Vandenberg, Scott R; Van Meir, Erwin G; von Deimling, Andreas; Zhang, Hailei; Crain, Daniel; Lau, Kevin; Mallery, David; Morris, Scott; Paulauskis, Joseph; Penny, Robert; Shelton, Troy; Sherman, Mark; Yena, Peggy; Black, Aaron; Bowen, Jay; Dicostanzo, Katie; Gastier-Foster, Julie; Leraas, Kristen M; Lichtenberg, Tara M; Pierson, Christopher R; Ramirez, Nilsa C; Taylor, Cynthia; Weaver, Stephanie; Wise, Lisa; Zmuda, Erik; Davidsen, Tanja; Demchok, John A; Eley, Greg; Ferguson, Martin L; Hutter, Carolyn M; Mills Shaw, Kenna R; Ozenberger, Bradley A; Sheth, Margi; Sofia, Heidi J; Tarnuzzer, Roy; Wang, Zhining; Yang, Liming; Zenklusen, Jean Claude; Ayala, Brenda; Baboud, Julien; Chudamani, Sudha; Jensen, Mark A; Liu, Jia; Pihl, Todd; Raman, Rohini; Wan, Yunhu; Wu, Ye; Ally, Adrian; Auman, J Todd; Balasundaram, Miruna; Balu, Saianand; Baylin, Stephen B; Beroukhim, Rameen; Bootwalla, Moiz S; Bowlby, Reanne; Bristow, Christopher A; Brooks, Denise; Butterfield, Yaron; Carlsen, Rebecca; Carter, Scott; Chin, Lynda; Chu, Andy; Chuah, Eric; Cibulskis, Kristian; Clarke, Amanda; Coetzee, Simon G; Dhalla, Noreen; Fennell, Tim; Fisher, Sheila; Gabriel, Stacey; Getz, Gad; Gibbs, Richard; Guin, Ranabir; Hadjipanayis, Angela; Hayes, D Neil; Hinoue, Toshinori; Hoadley, Katherine; Holt, Robert A; Hoyle, Alan P; Jefferys, Stuart R; Jones, Steven; Jones, Corbin D; Kucherlapati, Raju; Lai, Phillip H; Lander, Eric; Lee, Semin; Lichtenstein, Lee; Ma, Yussanne; Maglinte, Dennis T; Mahadeshwar, Harshad S; Marra, Marco A; Mayo, Michael; Meng, Shaowu; Meyerson, Matthew L; Mieczkowski, Piotr A; Moore, Richard A; Mose, Lisle E; Mungall, Andrew J; Pantazi, Angeliki; Parfenov, Michael; Park, Peter J; Parker, Joel S; Perou, Charles M; Protopopov, Alexei; Ren, Xiaojia; Roach, Jeffrey; Sabedot, Thaís S; Schein, Jacqueline; Schumacher, Steven E; Seidman, Jonathan G; Seth, Sahil; Shen, Hui; Simons, Janae V; Sipahimalani, Payal; Soloway, Matthew G; Song, Xingzhi; Sun, Huandong; Tabak, Barbara; Tam, Angela; Tan, Donghui; Tang, Jiabin; Thiessen, Nina; Triche, Timothy; Van Den Berg, David J; Veluvolu, Umadevi; Waring, Scot; Weisenberger, Daniel J; Wilkerson, Matthew D; Wong, Tina; Wu, Junyuan; Xi, Liu; Xu, Andrew W; Yang, Lixing; Zack, Travis I; Zhang, Jianhua; Aksoy, B Arman; Arachchi, Harindra; Benz, Chris; Bernard, Brady; Carlin, Daniel; Cho, Juok; DiCara, Daniel; Frazer, Scott; Fuller, Gregory N; Gao, JianJiong; Gehlenborg, Nils; Haussler, David; Heiman, David I; Iype, Lisa; Jacobsen, Anders; Ju, Zhenlin; Katzman, Sol; Kim, Hoon; Knijnenburg, Theo; Kreisberg, Richard Bailey; Lawrence, Michael S; Lee, William; Leinonen, Kalle; Lin, Pei; Ling, Shiyun; Liu, Wenbin; Liu, Yingchun; Liu, Yuexin; Lu, Yiling; Mills, Gordon; Ng, Sam; Noble, Michael S; Paull, Evan; Rao, Arvind; Reynolds, Sheila; Saksena, Gordon; Sanborn, Zack; Sander, Chris; Schultz, Nikolaus; Senbabaoglu, Yasin; Shen, Ronglai; Shmulevich, Ilya; Sinha, Rileen; Stuart, Josh; Sumer, S Onur; Sun, Yichao; Tasman, Natalie; Taylor, Barry S; Voet, Doug; Weinhold, Nils; Weinstein, John N; Yang, Da; Yoshihara, Kosuke; Zheng, Siyuan; Zhang, Wei; Zou, Lihua; Abel, Ty; Sadeghi, Sara; Cohen, Mark L; Eschbacher, Jenny; Hattab, Eyas M; Raghunathan, Aditya; Schniederjan, Matthew J; Aziz, Dina; Barnett, Gene; Barrett, Wendi; Bigner, Darell D; Boice, Lori; Brewer, Cathy; Calatozzolo, Chiara; Campos, Benito; Carlotti, Carlos Gilberto; Chan, Timothy A; Cuppini, Lucia; Curley, Erin; Cuzzubbo, Stefania; Devine, Karen; DiMeco, Francesco; Duell, Rebecca; Elder, J Bradley; Fehrenbach, Ashley; Finocchiaro, Gaetano; Friedman, William; Fulop, Jordonna; Gardner, Johanna; Hermes, Beth; Herold-Mende, Christel; Jungk, Christine; Kendler, Ady; Lehman, Norman L; Lipp, Eric; Liu, Ouida; Mandt, Randy; McGraw, Mary; Mclendon, Roger; McPherson, Christopher; Neder, Luciano; Nguyen, Phuong; Noss, Ardene; Nunziata, Raffaele; Ostrom, Quinn T; Palmer, Cheryl; Perin, Alessandro; Pollo, Bianca; Potapov, Alexander; Potapova, Olga; Rathmell, W Kimryn; Rotin, Daniil; Scarpace, Lisa; Schilero, Cathy; Senecal, Kelly; Shimmel, Kristen; Shurkhay, Vsevolod; Sifri, Suzanne; Singh, Rosy; Sloan, Andrew E; Smolenski, Kathy; Staugaitis, Susan M; Steele, Ruth; Thorne, Leigh; Tirapelli, Daniela P C; Unterberg, Andreas; Vallurupalli, Mahitha; Wang, Yun; Warnick, Ronald; Williams, Felicia; Wolinsky, Yingli; Bell, Sue; Rosenberg, Mara; Stewart, Chip; Huang, Franklin; Grimsby, Jonna L; Radenbaugh, Amie J; Zhang, Jianan

2015-06-25

Diffuse low-grade and intermediate-grade gliomas (which together make up the lower-grade gliomas, World Health Organization grades II and III) have highly variable clinical behavior that is not adequately predicted on the basis of histologic class. Some are indolent; others quickly progress to glioblastoma. The uncertainty is compounded by interobserver variability in histologic diagnosis. Mutations in IDH, TP53, and ATRX and codeletion of chromosome arms 1p and 19q (1p/19q codeletion) have been implicated as clinically relevant markers of lower-grade gliomas. We performed genomewide analyses of 293 lower-grade gliomas from adults, incorporating exome sequence, DNA copy number, DNA methylation, messenger RNA expression, microRNA expression, and targeted protein expression. These data were integrated and tested for correlation with clinical outcomes. Unsupervised clustering of mutations and data from RNA, DNA-copy-number, and DNA-methylation platforms uncovered concordant classification of three robust, nonoverlapping, prognostically significant subtypes of lower-grade glioma that were captured more accurately by IDH, 1p/19q, and TP53 status than by histologic class. Patients who had lower-grade gliomas with an IDH mutation and 1p/19q codeletion had the most favorable clinical outcomes. Their gliomas harbored mutations in CIC, FUBP1, NOTCH1, and the TERT promoter. Nearly all lower-grade gliomas with IDH mutations and no 1p/19q codeletion had mutations in TP53 (94%) and ATRX inactivation (86%). The large majority of lower-grade gliomas without an IDH mutation had genomic aberrations and clinical behavior strikingly similar to those found in primary glioblastoma. The integration of genomewide data from multiple platforms delineated three molecular classes of lower-grade gliomas that were more concordant with IDH, 1p/19q, and TP53 status than with histologic class. Lower-grade gliomas with an IDH mutation either had 1p/19q codeletion or carried a TP53 mutation. Most lower-grade gliomas without an IDH mutation were molecularly and clinically similar to glioblastoma. (Funded by the National Institutes of Health.).

Accumulation of p53 is associated with tumour progression in cutaneous lesions of renal allograft recipients.

PubMed Central

Stark, L. A.; Arends, M. J.; McLaren, K. M.; Benton, E. C.; Shahidullah, H.; Hunter, J. A.; Bird, C. C.

1994-01-01

Renal allograft recipients suffer from a markedly increased susceptibility to premalignant and malignant cutaneous lesions. Although various aetiological factors have been implicated, little is known of the associated genetic events. In this study we initially employed immunocytochemical techniques to investigate the prevalence and localisation of accumulated p53 in over 200 cutaneous biopsies (including 56 squamous cell carcinomas) from renal allograft recipients and immunocompetent controls. In renal allograft recipients accumulated p53 was present in 24% of uninvolved skin samples, 14% of viral warts, 41% of premalignant keratoses, 65% of intraepidermal carcinomas and 56% of squamous cell carcinomas [squamous cell carcinoma and intraepidermal carcinoma differed significantly from uninvolved skin (P < 0.005) and viral warts (P < 0.01)]. A similar trend was revealed in immunocompetent patients (an older, chronically sun-exposed population) but with lower prevalence of p53 immunoreactivity: 25% of uninvolved skin samples, 0% of viral warts, 25% of keratoses, 53% of intraepidermal carcinomas and 53% of squamous cell carcinomas. These differences were not statistically significant. Morphologically, p53 immunoreactivity strongly associated with areas of epidermal dysplasia and the abundance of staining correlated positively with the severity of dysplasia. These data suggest that p53 plays a role in skin carcinogenesis and is associated with progression towards the invasive state. No correlation was observed between accumulated p53 and the presence of human papillomavirus (HPV) DNA in any of the lesions. Single-strand conformational polymorphism analysis (exons 5-8) was used to determine the frequency of mutated p53 in 28 malignancies with varying degrees of immunopositivity. p53 mutations were found in 5/9 (56%) malignancies with p53 staining in > 50% of cells, reducing to 1/6 (17%) where 10-50% of cells were positively stained and none where < 10% of cells were stained. These data imply that factors other than p53 gene mutation play a part in accumulation of p53 in skin cancers. Images Figure 2 Figure 3 PMID:7917913

Evasion of cell senescence in SHH medulloblastoma.

PubMed

Tamayo-Orrego, Lukas; Swikert, Shannon M; Charron, Frédéric

2016-08-17

The mechanisms leading to brain tumor formation are poorly understood. Using Ptch1 +/- mice as a medulloblastoma model, sequential mutations were found to shape tumor evolution. Initially, medulloblastoma preneoplastic lesions display loss of heterozygosity of the Ptch1 wild-type allele, an event associated with cell senescence in preneoplasia. Subsequently, p53 mutations lead to senescence evasion and progression from preneoplasia to medulloblastoma. These findings are consistent with a model where high levels of Hedgehog signaling caused by the loss of the tumor suppressor Ptch1 lead to oncogene-induced senescence and drive p53 mutations. Thus, cell senescence is an important characteristic of a subset of SHH medulloblastoma and might explain the acquisition of somatic TP53 mutations in human medulloblastoma. This mode of medulloblastoma formation contrasts with the one characterizing Li-Fraumeni patients with medulloblastoma, where TP53 germ-line mutations cause chromothriptic genomic instability and lead to mutations in Hedgehog signaling genes, which drive medulloblastoma growth. Here we discuss in detail these 2 alternative mechanisms leading to medulloblastoma tumorigenesis.

Evasion of cell senescence in SHH medulloblastoma

PubMed Central

Tamayo-Orrego, Lukas; Swikert, Shannon M.; Charron, Frédéric

2016-01-01

ABSTRACT The mechanisms leading to brain tumor formation are poorly understood. Using Ptch1+/− mice as a medulloblastoma model, sequential mutations were found to shape tumor evolution. Initially, medulloblastoma preneoplastic lesions display loss of heterozygosity of the Ptch1 wild-type allele, an event associated with cell senescence in preneoplasia. Subsequently, p53 mutations lead to senescence evasion and progression from preneoplasia to medulloblastoma. These findings are consistent with a model where high levels of Hedgehog signaling caused by the loss of the tumor suppressor Ptch1 lead to oncogene-induced senescence and drive p53 mutations. Thus, cell senescence is an important characteristic of a subset of SHH medulloblastoma and might explain the acquisition of somatic TP53 mutations in human medulloblastoma. This mode of medulloblastoma formation contrasts with the one characterizing Li-Fraumeni patients with medulloblastoma, where TP53 germ-line mutations cause chromothriptic genomic instability and lead to mutations in Hedgehog signaling genes, which drive medulloblastoma growth. Here we discuss in detail these 2 alternative mechanisms leading to medulloblastoma tumorigenesis. PMID:27229128

Tetramer formation of tumor suppressor protein p53: Structure, function, and applications.

PubMed

Kamada, Rui; Toguchi, Yu; Nomura, Takao; Imagawa, Toshiaki; Sakaguchi, Kazuyasu

2016-11-04

Tetramer formation of p53 is essential for its tumor suppressor function. p53 not only acts as a tumor suppressor protein by inducing cell cycle arrest and apoptosis in response to genotoxic stress, but it also regulates other cellular processes, including autophagy, stem cell self-renewal, and reprogramming of differentiated cells into stem cells, immune system, and metastasis. More than 50% of human tumors have TP53 gene mutations, and most of them are missense mutations that presumably reduce tumor suppressor activity of p53. This review focuses on the role of the tetramerization (oligomerization), which is modulated by the protein concentration of p53, posttranslational modifications, and/or interactions with its binding proteins, in regulating the tumor suppressor function of p53. Functional control of p53 by stabilizing or inhibiting oligomer formation and its bio-applications are also discussed. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 598-612, 2016. © 2015 Wiley Periodicals, Inc.

2-Sulfonylpyrimidines: Mild alkylating agents with anticancer activity toward p53-compromised cells.

PubMed

Bauer, Matthias R; Joerger, Andreas C; Fersht, Alan R

2016-09-06

The tumor suppressor p53 has the most frequently mutated gene in human cancers. Many of p53's oncogenic mutants are just destabilized and rapidly aggregate, and are targets for stabilization by drugs. We found certain 2-sulfonylpyrimidines, including one named PK11007, to be mild thiol alkylators with anticancer activity in several cell lines, especially those with mutationally compromised p53. PK11007 acted by two routes: p53 dependent and p53 independent. PK11007 stabilized p53 in vitro via selective alkylation of two surface-exposed cysteines without compromising its DNA binding activity. Unstable p53 was reactivated by PK11007 in some cancer cell lines, leading to up-regulation of p53 target genes such as p21 and PUMA. More generally, there was cell death that was independent of p53 but dependent on glutathione depletion and associated with highly elevated levels of reactive oxygen species and induction of endoplasmic reticulum (ER) stress, as also found for the anticancer agent PRIMA-1(MET)(APR-246). PK11007 may be a lead for anticancer drugs that target cells with nonfunctional p53 or impaired reactive oxygen species (ROS) detoxification in a wide variety of mutant p53 cells.

Genomic analysis of the origins and evolution of multicentric diffuse lower-grade gliomas.

PubMed

Hayes, Josie; Yu, Yao; Jalbert, Llewellyn E; Mazor, Tali; Jones, Lindsey E; Wood, Matthew D; Walsh, Kyle M; Bengtsson, Henrik; Hong, Chibo; Oberndorfer, Stefan; Roetzer, Thomas; Smirnov, Ivan V; Clarke, Jennifer L; Aghi, Manish K; Chang, Susan M; Nelson, Sarah J; Woehrer, Adelheid; Phillips, Joanna J; Solomon, David A; Costello, Joseph F

2018-04-09

Rare multicentric lower-grade gliomas (LGGs) represent a unique opportunity to study the heterogeneity among distinct tumor foci in a single patient and to infer their origins and parallel patterns of evolution. In this study, we integrate clinical features, histology, and immunohistochemistry for 4 patients with multicentric LGG, arising both synchronously and metachronously. For 3 patients we analyze the phylogeny of the lesions using exome sequencing, including one case with a total of 8 samples from the 2 lesions. One patient was diagnosed with multicentric isocitrate dehydrogenase 1 (IDH1) mutated diffuse astrocytomas harboring distinct IDH1 mutations, R132H and R132C; the latter mutation has been associated with Li-Fraumeni syndrome, which was subsequently confirmed in the patient's germline DNA and shown in additional cases with The Cancer Genome Atlas data. In another patient, phylogenetic analysis of synchronously arising grade II and grade III diffuse astrocytomas demonstrated a single shared mutation, IDH1 R132H, and revealed convergent evolution via non-overlapping mutations in ATRX and TP53. In 2 cases, there was divergent evolution of IDH1-mutated and 1p/19q-codeleted oligodendroglioma and IDH1-mutated and 1p/19q-intact diffuse astrocytoma, occurring synchronously in one case and metachronously in a second. Each tumor in multicentric LGG cases may arise independently or may diverge very early in their development, presenting as genetically and histologically distinct tumors. Comprehensive sampling of these lesions can therefore significantly alter diagnosis and management. Additionally, somatic IDH1 R132C mutation in either multicentric or solitary LGG identifies unsuspected germline TP53 mutation, validating the limited number of published cases.

hOGG1 Ser326Cys polymorphism and G:C-to-T:A mutations: no evidence for a role in tobacco-related non small cell lung cancer.

PubMed

Hu, Ying Chuan; Ahrendt, Steven A

2005-04-10

Human 8-oxoguanine DNA glycosylase 1 (hOGG1) plays a major role in the repair of 8-hydroxyguanine, one of the major forms of DNA damage generated by reactive oxygen species in tobacco smoke. If left unrepaired by hOGG1, 8-hydroxyguanine can produce G:C-to-T:A transversions. Recent studies have suggested that the hOGG1 Ser326Cys polymorphism is associated with both a decrease in enzyme activity and an increased risk of lung cancer. To define the interaction between tobacco carcinogens, hOGG1-mediated DNA repair and DNA damage, we examined the role of the hOGG1 Ser326Cys polymorphism in mutation of the p53 gene in non small cell lung cancer (NSCLC). Tumor and nonneoplastic DNA were collected from 141 cigarette smokers with NSCLC. p53 mutations were detected by direct dideoxy sequencing and/or the GeneChip p53 assay in 74 of the 141 (52%) tumors. hOGG1 codon 326 polymorphisms were identified by polymerase chain reaction-restriction fragment length polymorphism analysis. The distribution of hOGG1 codon 326 genotypes was Ser/Ser, 90 of 141 (64%); Ser/Cys, 45 of 141 (32%); and Cys/Cys, 6 of 141 (4%). p53 mutations were significantly (p = 0.04) less common in NSCLC from patients with codon 326 Ser/Cys or Cys/Cys genotypes (21 of 51; 41%) than in NSCLC from Ser/Ser homozygotes (53 of 90; 59%). The decrease in p53 mutation frequency among carriers of the Cys allele was more evident in lung squamous cell cancer [7 of 17 (41%) for Cys/Cys and Ser/Cys vs. 27 of 38 (71%) for Ser/Ser; p = 0.04] than in nonbronchoalveolar adenocarcinoma [11 of 26 (42%) for Cys/Cys and Ser/Cys vs. 20 of 35 (57%) for Ser/Ser; p = 0.25]. The prevalence of G:C-to-T:A transversions was similar among hOGG1 codon 326 genotypes. In summary, the hOGG1 codon 326 Cys allele was associated with a decrease in p53 mutations and no effect on G:C-to-T:A transversions in NSCLC. This decrease in p53 mutations in vivo is not consistent with a decrease in the repair of 8-hydroxyguanine among carriers of the hOGG1 codon 326 Cys allele in vitro. (c) 2004 Wiley-Liss, Inc.

Regulators of apoptosis in cholangiocarcinoma.

PubMed

Jhala, Nirag C; Vickers, Selwyn M; Argani, Pedram; McDonald, Jay M

2005-04-01

Dysregulation of mediators of apoptosis is associated with carcinogenesis. For biliary duct cancers, p53 gene mutation is an important contributor to carcinogenesis. Mutations in the p53 gene affect transcription of the Fas gene, resulting in lack of Fas expression on cell membrane. It has been previously shown that cloned Fas-negative but not Fas-positive human cholangiocarcinoma cells are resistant to anti-Fas-mediated apoptosis and develop tumors in nude mice. In addition, interferon gamma induces Fas expression in Fas-negative cholangiocarcinoma cells and makes them susceptible to apoptosis. Therefore, it becomes important to characterize immunophenotypic expression of p53 and Fas in normal and neoplastic human tissues of the biliary tract to further understand the pathogenesis of the disease. To date, human studies to characterize differences in immunophenotypic expression of the Fas protein between intrahepatic and extrahepatic biliary duct cancers and in their precursor lesions have not been performed. To report the immunophenotypic expression of p53 and Fas expression in various stages in the development of bile duct cancers (intrahepatic and extrahepatic tumor location) and their association with tumor differentiation. Thirty bile duct cancer samples (13 intrahepatic and 17 extrahepatic) from 18 men and 12 women who ranged in age from 44 to 77 years (mean age, 65.6 years) were retrieved from the surgical pathology files. Hematoxylin-eosin-stained slides were evaluated for the type and grade of tumor and dysplastic changes in the biliary tract epithelium. Additional slides were immunohistochemically stained with p53 and anti-Fas mouse monoclonal antibody. The pattern of Fas distribution and percentage of cells positive for p53 and Fas expression were determined. The percentage of Fas-expressing cells is significantly (P = .01) more frequently noted in extrahepatic tumors compared with intrahepatic tumors. Furthermore, Fas expression decreased from dysplastic epithelium to cholangiocarcinoma (P = .01), and this decreasing trend continued from well to poorly differentiated tumors. Nuclear p53 expression was not identified in normal and dysplastic epithelium but was noted in 30% of carcinomas (P = .02). Fas expression is an early event in pathogenesis of bile duct cancers. Immunophenotypic expression of Fas is associated with well to moderately differentiated tumors but not with poor tumor differentiation.

HPV-negative penile squamous cell carcinoma: disruptive mutations in the TP53 gene are common.

PubMed

Kashofer, Karl; Winter, Elke; Halbwedl, Iris; Thueringer, Andrea; Kreiner, Marisa; Sauer, Stefan; Regauer, Sigrid

2017-07-01

The majority of penile squamous cell carcinomas is caused by transforming human papilloma virus (HPV) infection. The etiology of HPV-negative cancers is unclear, but TP53 mutations have been implicated. Archival tissues of 108 invasive squamous cell carcinoma from a single pathology institution in a low-incidence area were analyzed for HPV-DNA and p16 ink4a overexpression and for TP53 mutations by ion torrent next-generation sequencing. Library preparation failed in 32/108 squamous cell carcinomas. Institutional review board approval was obtained. Thirty of 76 squamous cell carcinomas (43%; average 63 years) were HPV-negative with 8/33 squamous cell carcinomas being TP53 wild-type (24%; average 63 years). Twenty-five of 33 squamous cell carcinomas (76%; average 65 years) showed 32 different somatic TP53 mutations (23 missense mutations in exons 5-8, 6 nonsense, 1 frameshift and 2 splice-site mutations). Several hotspot mutations were detected multiple times (R175H, R248, R282, and R273). Eighteen of 19 squamous cell carcinomas with TP53 expression in immunohistochemistry had TP53 mutations. Fifty percent of TP53-negative squamous cell carcinomas showed mostly truncating loss-of-function TP53 mutations. Patients without mutations had longer survival (5 years: 86% vs 61%; 10 years: 60% vs 22%), but valid clinically relevant conclusions cannot be drawn due to different tumor stages and heterogeneous treatment of the cases presented in this study. Somatic TP53 mutations are a common feature in HPV-negative penile squamous cell carcinomas and offer an explanation for HPV-independent penile carcinogenesis. About half of HPV-negative penile cancers are driven by oncogenic activation of TP53, while a quarter is induced by loss of TP53 tumor suppressor function. Detection of TP53 mutations should be carried out by sequencing, as immunohistochemical TP53 staining could not identify all squamous cell carcinomas with TP53 mutations.

Deletion of ribosomal protein genes is a common vulnerability in human cancer, especially in concert with TP53 mutations.

PubMed

Ajore, Ram; Raiser, David; McConkey, Marie; Jöud, Magnus; Boidol, Bernd; Mar, Brenton; Saksena, Gordon; Weinstock, David M; Armstrong, Scott; Ellis, Steven R; Ebert, Benjamin L; Nilsson, Björn

2017-04-01

Heterozygous inactivating mutations in ribosomal protein genes (RPGs) are associated with hematopoietic and developmental abnormalities, activation of p53, and altered risk of cancer in humans and model organisms. Here we performed a large-scale analysis of cancer genome data to examine the frequency and selective pressure of RPG lesions across human cancers. We found that hemizygous RPG deletions are common, occurring in about 43% of 10,744 cancer specimens and cell lines. Consistent with p53-dependent negative selection, such lesions are underrepresented in TP53 -intact tumors ( P  ≪ 10 -10 ), and shRNA-mediated knockdown of RPGs activated p53 in TP53 -wild-type cells. In contrast, we did not see negative selection of RPG deletions in TP53 -mutant tumors. RPGs are conserved with respect to homozygous deletions, and shRNA screening data from 174 cell lines demonstrate that further suppression of hemizygously deleted RPGs inhibits cell growth. Our results establish RPG haploinsufficiency as a strikingly common vulnerability of human cancers that associates with TP53 mutations and could be targetable therapeutically. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

Incorporation of p-53 mutation status and Ki-67 proliferating index in classifying Her2-neu positive gastric adenocarcinoma.

PubMed

Ahmed, Ayesha; Al-Tamimi, Dalal M

2018-12-01

Her2-neu overexpression has a pathogenetic, therapeutic and a controversial prognostic role in gastric cancer. p-53 mutation status and Ki-67 proliferation index are established prognostic markers in many tumors. In this study we evaluated p-53 and Ki-67 in relation to Her2-neu positive and negative gastric adenocarcinoma (GA). This cross-sectional study was carried out at King Fahd Hospital of Imam Abdulrahman bin Faisal University. Fifty cases of GA were retrieved from pathology archives. Clinico-pathological parameters were evaluated. Immunohistochemical protein analysis for Her2-neu, Ki-67 and p-53 was carried out. Fluorescent in situ hybridization (FISH) analysis was done for Her2-neu positive cases showing 2+ immunoexpression. Frequency of Ki-67 and p-53 positivity in Her2-neu positive cases was calculated and compared with those in Her2-neu negative cases. Correlation of clinicopatological parameters with Her2 positive and negative cases, p-53 mutation status and Ki-67 proliferation index was carried out. Her2-neu overexpression was present in 12% (n = 6) cases. A high Ki-67 was seen predominantly in Her2-neu positive cases (83%, n = 5). Her2-neu negative cases (n = 44) showed moderate (31.88%, n = 14) to low (34%, n = 15) Ki-67. Diffuse p-53 positivity was seen predominantly in Her2-neu positive cases (33.33%, n = 2). Focal p-53 was seen mainly in Her2-neu negative cases 56.8% (n = 25). Negative p-53 was seen to be independent of Her2-neu status. Her2-neu positivity is strongly associated with diffuse p-53 mutation status and high Ki-67 proliferation. Her 2-neu negative status is associated with focal p-53 positivity and low to moderate Ki-67 proliferation index. Such stratifications in prognostic markers could not only be predictive in patient's prognostics but could also form a basis of molecular classification of gastric cancer.

The impact of p53 on the early stage replication of retrovirus.

PubMed

Kinnetz, Michaela; Alghamdi, Faris; Racz, Michael; Hu, Wenwei; Shi, Binshan

2017-08-09

The function of p53 in cancer biology has been studied extensively, but its role in anti-retrovirus infection has been elusive for many years. The restriction of retrovirus early stage replication by p53 was investigated in this study. VSV-G pseudotyped retrovirus with GFP reporter gene was used to infect both HCT116 p53 +/+ cells and its isogenic p53 knockout HCT116 p53 -/- cells. The infection was detected by flow cytometry. Reverse transcription products were quantified by real time PCR. Mutation analysis was performed after 1-LTR cycle and 2-LTR cycle DNA were amplified and PCR products were sequenced. Transcription and translation of cyclin-dependent kinase inhibitor 1 (p21 Cip1 ) and SAM domain and HD domain-containing protein 1 (SAMHD1) were analyzed by TaqMan PCR and Western blot experiments. siRNA experiment was applied to study the role of p53 downstream gene p21 Cip1 in the restriction of retrovirus infection. It was found that the block of retrovirus infection in non-cycling cells was significantly attenuated in HCT116 p53 -/- cells when compared to HCT116 p53 +/+ cells. It was found that both late reverse transcription products and viral 2-LTR cycle DNA were significantly increased in infected non-cycling HCT116 p53 -/- cells. Furthermore, the mutation frequency detected in 1-LTR DNA from HCT116 p53 +/+ cells were significantly decreased in comparison to HCT116 p53 -/- cells. A higher number of insertion and deletion mutations were detected in the joint region of 2-LTR cycle DNA in infected p53 +/+ cells. Cell cycle analysis showed retrovirus infection promoted host cell replication. Higher levels of mRNA and protein of p21 Cip1 were found in HCT116 p53 +/+ cells in comparison to the HCT116 p53 -/- cells. Furthermore, knockdown of p21 Cip1 in non-cycling HCT116 p53 +/+ cells significantly increased the infection. The results of this study showed that p53 is an important restriction factor that interferes with retrovirus infection in its early stage of replication. Our results suggested that p53 mediates the inhibition of retrovirus infection in non-cycling cells through it downstream gene p21 Cip1 , and p53 also functions to influence formation of 1-LTR cycle and 2-LTR cycle DNA.

Activation of PTHrP-cAMP-CREB1 signaling following p53 loss is essential for osteosarcoma initiation and maintenance

PubMed Central

Walia, Mannu K; Ho, Patricia MW; Taylor, Scott; Ng, Alvin JM; Gupte, Ankita; Chalk, Alistair M; Zannettino, Andrew CW; Martin, T John; Walkley, Carl R

2016-01-01

Mutations in the P53 pathway are a hallmark of human cancer. The identification of pathways upon which p53-deficient cells depend could reveal therapeutic targets that may spare normal cells with intact p53. In contrast to P53 point mutations in other cancer, complete loss of P53 is a frequent event in osteosarcoma (OS), the most common cancer of bone. The consequences of p53 loss for osteoblastic cells and OS development are poorly understood. Here we use murine OS models to demonstrate that elevated Pthlh (Pthrp), cAMP levels and signalling via CREB1 are characteristic of both p53-deficient osteoblasts and OS. Normal osteoblasts survive depletion of both PTHrP and CREB1. In contrast, p53-deficient osteoblasts and OS depend upon continuous activation of this pathway and undergo proliferation arrest and apoptosis in the absence of PTHrP or CREB1. Our results identify the PTHrP-cAMP-CREB1 axis as an attractive pathway for therapeutic inhibition in OS. DOI: http://dx.doi.org/10.7554/eLife.13446.001 PMID:27070462

Structure-Based Design of Molecules to Reactivate Tumor-Derived p53 Mutations

DTIC Science & Technology

2006-06-01

fact, approximately half of the major forms of cancer contain p53 mutations, and the vast majority of these cluster in conserved regions or “hot...structures were subjected to 5.0 ns MD simulations using the program GROMACS 3.3 (Van Der Spoel et al., 2005). The RMSD values of backbone atoms from... analysis of residue-wise RMS fluctuations, shown in Figure 3B which shows that the stabilizing effect of Tris on the p53 core domain is distributed

P53 Mutation Profiles in Premenopausal Versus Postmenopausal Breast Cancer in a Stationary Population

DTIC Science & Technology

1997-08-01

Gryka , M ., Bischoff, F Z., Tainsky, M . A., Friend. S. H., 1990: Germ line p53 mutation in a familial syndrome of breast cancer, sarcomas, and...of relapse and survival with amplification of the HER-2/neu oncogene. Science 235:177-182 2. Prosser, J., Thompson, A. M ., Cranston, G and Evans, HJ...1990: Evidence that p53 behaves as a tumor suppressor gene in sporadic breast tumours. Oncogene 5:1573-1579. 3. Davidoff, A. M ., Kerns, B.J. M

Integrated genetic and epigenetic analysis identifies three different subclasses of colon cancer

PubMed Central

Shen, Lanlan; Toyota, Minoru; Kondo, Yutaka; Lin, E; Zhang, Li; Guo, Yi; Hernandez, Natalie Supunpong; Chen, Xinli; Ahmed, Saira; Konishi, Kazuo; Hamilton, Stanley R.; Issa, Jean-Pierre J.

2007-01-01

Colon cancer has been viewed as the result of progressive accumulation of genetic and epigenetic abnormalities. However, this view does not fully reflect the molecular heterogeneity of the disease. We have analyzed both genetic (mutations of BRAF, KRAS, and p53 and microsatellite instability) and epigenetic alterations (DNA methylation of 27 CpG island promoter regions) in 97 primary colorectal cancer patients. Two clustering analyses on the basis of either epigenetic profiling or a combination of genetic and epigenetic profiling were performed to identify subclasses with distinct molecular signatures. Unsupervised hierarchical clustering of the DNA methylation data identified three distinct groups of colon cancers named CpG island methylator phenotype (CIMP) 1, CIMP2, and CIMP negative. Genetically, these three groups correspond to very distinct profiles. CIMP1 are characterized by MSI (80%) and BRAF mutations (53%) and rare KRAS and p53 mutations (16% and 11%, respectively). CIMP2 is associated with 92% KRAS mutations and rare MSI, BRAF, or p53 mutations (0, 4, and 31% respectively). CIMP-negative cases have a high rate of p53 mutations (71%) and lower rates of MSI (12%) or mutations of BRAF (2%) or KRAS (33%). Clustering based on both genetic and epigenetic parameters also identifies three distinct (and homogeneous) groups that largely overlap with the previous classification. The three groups are independent of age, gender, or stage, but CIMP1 and 2 are more common in proximal tumors. Together, our integrated genetic and epigenetic analysis reveals that colon cancers correspond to three molecularly distinct subclasses of disease. PMID:18003927

Genomic Characterization of Upper Tract Urothelial Carcinoma.

PubMed

Sfakianos, John P; Cha, Eugene K; Iyer, Gopa; Scott, Sasinya N; Zabor, Emily C; Shah, Ronak H; Ren, Qinghu; Bagrodia, Aditya; Kim, Philip H; Hakimi, A Ari; Ostrovnaya, Irina; Ramirez, Ricardo; Hanrahan, Aphrothiti J; Desai, Neil B; Sun, Arony; Pinciroli, Patrizia; Rosenberg, Jonathan E; Dalbagni, Guido; Schultz, Nikolaus; Bajorin, Dean F; Reuter, Victor E; Berger, Michael F; Bochner, Bernard H; Al-Ahmadie, Hikmat A; Solit, David B; Coleman, Jonathan A

2015-12-01

Despite a similar histologic appearance, upper tract urothelial carcinoma (UTUC) and urothelial carcinoma of the bladder (UCB) tumors have distinct epidemiologic and clinicopathologic differences. To investigate whether the differences between UTUC and UCB result from intrinsic biological diversity. Tumor and germline DNA from patients with UTUC (n=83) and UCB (n=102) were analyzed using a custom next-generation sequencing assay to identify somatic mutations and copy number alterations in 300 cancer-associated genes. We described co-mutation patterns and copy number alterations in UTUC. We also compared mutation frequencies in high-grade UTUC (n=59) and high-grade UCB (n=102). Comparison of high-grade UTUC and UCB revealed significant differences in the prevalence of somatic alterations. Genes altered more commonly in high-grade UTUC included FGFR3 (35.6% vs 21.6%; p=0.065), HRAS (13.6% vs 1.0%; p=0.001), and CDKN2B (15.3% vs 3.9%; p=0.016). Genes less frequently mutated in high-grade UTUC included TP53 (25.4% vs 57.8%; p<0.001), RB1 (0.0% vs 18.6%; p<0.001), and ARID1A (13.6% vs 27.5%; p=0.050). Because our assay was restricted to genomic alterations in a targeted panel, rare mutations and epigenetic changes were not analyzed. High-grade UTUC tumors display a spectrum of genetic alterations similar to high-grade UCB. However, there were significant differences in the prevalence of several recurrently mutated genes including HRAS, TP53, and RB1. As relevant targeted inhibitors are being developed and tested, these results may have important implications for the site-specific management of patients with urothelial carcinoma. Comparison of next-generation sequencing of upper tract urothelial carcinoma (UTUC) with urothelial bladder cancer identified that similar mutations were present in both cancer types but at different frequencies, indicating a potential need for unique management strategies. UTUC tumors were found to have a high rate of mutations that could be targeted with novel therapies. Copyright © 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Thirtyfold multiplex genotyping of the p53 gene using solid phase capturable dideoxynucleotides and mass spectrometry.

PubMed

Kim, Sobin; Ulz, Michael E; Nguyen, Tuan; Li, Chi-Ming; Sato, Takaaki; Tycko, Benjamin; Ju, Jingyue

2004-05-01

A mass spectrometry (MS) based multiplex genotyping method using solid phase capturable (SPC) dideoxynucleotides and single base extension (SBE), named the SPC-SBE, has been developed for mutation detection. We report here the simultaneous genotyping of 30 potential point mutation sites in exons 5, 7, and 8 of the human p53 gene in one tube using the SPC-SBE method. The 30 mutation sites, including the most frequently mutated p53 codons, were chosen to explore the high multiplexing scope of the SPC-SBE method. Thirty primers specific to each potential mutation site were designed to yield SBE products with sufficient mass differences. This was achieved by tuning the mass of some primers using modified nucleotides. Genomic DNA was amplified by multiplex PCR to produce amplicons of the three p53 exons. The 30 primers were combined with the PCR products and biotinylated dideoxynucleotides for SBE to generate 3'-biotinylated extension DNA products. These products were then captured by streptavidin-coated magnetic beads, while the unextended primers and other components in the reaction were washed away. The pure extension DNA products were subsequently released from the solid phase and analyzed with MS. We simultaneously genotyped 30 potential mutation sites in the p53 gene from Wilms' tumor, head and neck tumor, and colorectal tumor. Both homozygous and heterozygous genotypes were accurately determined with digital resolution. This is the highest level of multiplex genotyping reported thus far using MS, indicating that the approach might be applicable to screening a repertoire of genotypes in candidate genes as potential disease markers.

Relationship among tobacco habits, human papilloma virus (HPV) infection, p53 polymorphism/mutation and the risk of oral squamous cell carcinoma.

PubMed

Chakrobarty, Bidyut; Roy, Jay Gopal; Majumdar, Sumit; Uppala, Divya

2014-05-01

The prevalence of oral squamous cell carcinoma (OSCC) has significantly increased over decades in several countries and human papilloma virus (HPV) has been indicated as one of the underlying causes. This suggests that HPV plays a role in the early stages of carcinogenesis but is not a requisite for the maintenance and progression of malignant state. p53 is a tumor suppressor gene that checks the cell and promotes apoptosis and cell repair that can be deactivated by mutations and a viral interaction leading to cancer and individuals with particular polymorphic variant of p53 is more susceptible to HPV-induced carcinogenesis. The present study has been carried out to detect and correlate p53 polymorphism/mutation, HPV DNA in the biopsy samples of oral cancer patients who had tobacco habits.

Drug Resistance to Inhibitors of the Human Double Minute-2 E3 Ligase is Mediated by Point Mutations of p53, but can be Overcome with the p53 Targeting Agent RITA

PubMed Central

Jones, Richard J.; Bjorklund, Chad C.; Baladandayuthapani, Veerabhadran; Kuhn, Deborah J.; Orlowski, Robert Z.

2012-01-01

The human double minute (HDM)-2 E3 ubiquitin ligase plays a key role in p53 turnover, and has been validated pre-clinically as a target in multiple myeloma (MM) and mantle cell lymphoma (MCL). HDM-2 inhibitors are entering clinical trials, and we therefore sought to understand potential mechanisms of resistance in lymphoid models. Wild-type p53 H929 MM and Granta-519 MCL cells resistant to MI-63 or Nutlin were generated by exposing them to increasing drug concentrations. MI-63-resistant H929 and Granta-519 cells were resistant to Nutlin, while Nutlin-resistant cells displayed cross-resistance to MI-63. These cells also showed cross-resistance to bortezomib, doxorubicin, cisplatin, and melphalan, but remained sensitive to the small molecule inhibitor RITA. HDM-2 inhibitor-resistant cells harbored increased p53 levels, but neither genotoxic nor non-genotoxic approaches to activate p53 induced HDM-2 or p21. Resequencing revealed wild-type HDM-2, but mutations were found in the p53 DNA binding and dimerization domains. In resistant cells, RITA induced a G2/M arrest, up-regulation of p53 targets HDM-2, PUMA, and NOXA, and PARP cleavage. Combination regimens with RITA and MI-63 resulted in enhanced cell death compared to RITA alone. These findings support the possibility that p53 mutation could be a primary mechanism of acquired resistance to HDM-2 inhibitors in MCL and MM. Furthermore, they suggest that simultaneous restoration of p53 function and HDM-2 inhibition is a rational strategy for clinical translation. PMID:22933706

p53-independent p21 induction by MELK inhibition.

PubMed

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

2017-08-29

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

p53-independent p21 induction by MELK inhibition

PubMed Central

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

2017-01-01

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

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

PubMed

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

2015-10-01

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

Family matters: sibling rivalry and bonding between p53 and p63 in cancer.

PubMed

Romano, Rose-Anne; Sinha, Satrajit

2014-04-01

The p53 family (p53, p63 and p73) is intimately linked with an overwhelming number of cellular processes during normal physiological as well as pathological conditions including cancer. The fact that these proteins are expressed in myriad isoforms, each with unique biochemical properties and distinct effects on tumorigenesis, complicates their study. A case in point is Squamous Cell Carcinoma (SCC) where p53 is often mutated and the ΔNp63 isoform is overexpressed. Given that p53 and p63 can hetero-dimerize, bind to quite similar DNA elements and share common co-factors, any alterations in their individual expression levels, activity and/or mutation can severely disrupt the family equilibrium. The burgeoning genomics data sets and new additions to the experimental toolbox are offering crucial insights into the complex role of the p53 family in SCC, but more mechanistic studies are needed. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Rpl27a mutation in the sooty foot ataxia mouse phenocopies high p53 mouse models

PubMed Central

Terzian, Tamara; Dumble, Melissa; Arbab, Farinaz; Thaller, Christina; Donehower, Lawrence A; Lozano, Guillermina; Justice, Monica J; Roop, Dennis R; Box, Neil F

2013-01-01

Ribosomal stress is an important, yet poorly understood, mechanism that results in activation of the p53 tumour suppressor. We present a mutation in the ribosomal protein Rpl27a gene (sooty foot ataxia mice), isolated through a sensitized N-ethyl-N-nitrosourea (ENU) mutagenesis screen for p53 pathway defects, that shares striking phenotypic similarities with high p53 mouse models, including cerebellar ataxia, pancytopenia and epidermal hyperpigmentation. This phenocopy is rescued in a haploinsufficient p53 background. A detailed examination of the bone marrow in these mice identified reduced numbers of haematopoietic stem cells and a p53-dependent c-Kit down-regulation. These studies suggest that reduced Rpl27a increases p53 activity in vivo, further evident with a delay in tumorigenesis in mutant mice. Taken together, these data demonstrate that Rpl27a plays a crucial role in multiple tissues and that disruption of this ribosomal protein affects both development and transformation. PMID:21674502

Evaluation of p53 Polymorphism in Patients with Pannus-Derived Prosthetic Dysfunction.

PubMed

Gursoy, Mustafa Ozan; Karakoyun, Suleyman; Kalcik, Macit; Yesin, Mahmut; Gunduz, Sabahattin; Astarcioğlu, Mehmet Ali; Oğuz, Ali Emrah; Ozkan, Mehmet

2015-09-01

Prosthetic valve dysfunction (PVD) due to pannus formation is considered to occur due to a bioreaction to prosthetic material. The p53 gene plays a critical role in apoptosis and cell proliferation. p53 Arg72Pro polymorphism has been found to be associated with coronary stent restenosis, but has not yet been studied in prosthetic heart valve dysfunction. The study aim was to evaluate the association between pannus-derived PVD and p53 G72C(Arg72Pro) polymorphism. This single-center, prospective study included 25 patients (20 females, five males; mean age 45.6 +/- 12.5 years; group 1) who underwent redo valve surgery due to PVD, and 49 age- and gender-matched control patients (44 females, five males; mean age 47.3 +/- 12.2 years; group 2) with normofunctional prostheses. The prostheses were examined using transthoracic and transesophageal echocardiography. Analyses of p53 G72C(Arg72Pro) polymorphism were performed using Roche LightCyler 2.0 Real-time polymerase chain reaction. The most common location of replaced valves was the mitral position in both groups (88% and 89.8%, respectively). In group 1, normal alleles (GG) were observed in 12 patients (48%), while one patient (4%) showed a homozygous mutation (GC) and 12 patients (48%) showed a heterozygous mutation (CC). In group 2, 21 patients (42.9%) had normal alleles (GG), while four (8.2%) had a homozygous mutation (CC) and 24 (48.9%) had a heterozygous mutation (GC). No significant difference was observed between the groups with regards to p53 Arg72Pro polymorphism (p = 0.769). In patients with prosthetic valves, the underlying mechanism behind pannus formation is unrelated to p53 Arg72Pro polymorphism.

p21 controls patterning but not homologous recombination in RPE development.

PubMed

Bishop, A J R; Kosaras, B; Hollander, M C; Fornace, A; Sidman, R L; Schiestl, R H

2006-01-05

p21/WAF1/CIP1/MDA6 is a key cell cycle regulator. Cell cycle regulation is an important part of development, differentiation, DNA repair and apoptosis. Following DNA damage, p53 dependent expression of p21 results in a rapid cell cycle arrest. p21 also appears to be important for the development of melanocytes, promoting their differentiation and melanogenesis. Here, we examine the effect of p21 deficiency on the development of another pigmented tissue, the retinal pigment epithelium. The murine mutation pink-eyed unstable (p(un)) spontaneously reverts to a wild-type allele by homologous recombination. In a retinal pigment epithelium cell this results in pigmentation, which can be observed in the adult eye. The clonal expansion of such cells during development has provided insight into the pattern of retinal pigment epithelium development. In contrast to previous results with Atm, p53 and Gadd45, p(un) reversion events in p21 deficient mice did not show any significant change. These results suggest that p21 does not play any role in maintaining overall genomic stability by regulating homologous recombination frequencies during development. However, the absence of p21 caused a distinct change in the positions of the reversion events within the retinal pigment epithelium. Those events that would normally arrest to produce single cell events continued to proliferate uncovering a cell cycle dysregulation phenotype. It is likely that p21 is involved in controlling the developmental pattern of the retinal pigment. We also found a C57BL/6J specific p21 dependent ocular defect in retinal folding, similar to those reported in the absence of p53.

The yeast p53 functional assay: a new tool for molecular epidemiology. Hopes and facts.

PubMed

Fronza, G; Inga, A; Monti, P; Scott, G; Campomenosi, P; Menichini, P; Ottaggio, L; Viaggi, S; Burns, P A; Gold, B; Abbondandolo, A

2000-04-01

The assumption of molecular epidemiology that carcinogens leave fingerprints has suggested that analysis of the frequency, type, and site of mutations in genes frequently altered in carcinogenesis may provide clues to the identification of the factors contributing to carcinogenesis. In this mini-review, we revise the development, and validation of the yeast-based p53 functional assay as a new tool for molecular epidemiology. We show that this assay has some very interesting virtues but also has some drawbacks. The yeast functional assay can be used to determine highly specific mutation fingerprints in the human p53 cDNA sequence. Discrimination is possible when comparing mutation spectra induced by sufficiently different mutagens. However, we also reported that the same carcinogen may induce distinguishable mutation spectra due to known influencing factors.

Mutant p53 Promotes Tumor Cell Malignancy by Both Positive and Negative Regulation of the Transforming Growth Factor β (TGF-β) Pathway*

PubMed Central

Ji, Lei; Xu, Jinjin; Liu, Jian; Amjad, Ali; Zhang, Kun; Liu, Qingwu; Zhou, Lei; Xiao, Jianru; Li, Xiaotao

2015-01-01

Specific p53 mutations abrogate tumor-suppressive functions by gaining new abilities to promote tumorigenesis. Inactivation of p53 is known to distort TGF-β signaling, which paradoxically displays both tumor-suppressive and pro-oncogenic functions. The molecular mechanisms of how mutant p53 simultaneously antagonizes the tumor-suppressive and synergizes the tumor-promoting function of the TGF-β pathway remain elusive. Here we demonstrate that mutant p53 differentially regulates subsets of TGF-β target genes by enhanced binding to the MH2 domain in Smad3 upon the integration of ERK signaling, therefore disrupting Smad3/Smad4 complex formation. Silencing Smad2, inhibition of ERK, or introducing a phosphorylation-defective mutation at Ser-392 in p53 abrogates the R175H mutant p53-dependent regulation of these TGF-β target genes. Our study shows a mechanism to reconcile the seemingly contradictory observations that mutant p53 can both attenuate and cooperate with the TGF-β pathway to promote cancer cell malignancy in the same cell type. PMID:25767119

Down-regulation of p21 (CDKN1A/CIP1) is inversely associated with microsatellite instability and CpG island methylator phenotype (CIMP) in colorectal cancer.

PubMed

Ogino, S; Kawasaki, T; Kirkner, G J; Ogawa, A; Dorfman, I; Loda, M; Fuchs, C S

2006-10-01

p21 (CDKN1A/CIP1/WAF1), one of the cyclin-dependent kinase inhibitors, plays a key role in regulating the cell cycle and is transcriptionally regulated by p53. Down-regulation of p21 is caused by TP53 mutations in colorectal cancer. CpG island methylator phenotype (CIMP) appears to be a distinct subtype of colorectal cancer with concordant methylation of multiple gene promoters and is associated with a high degree of microsatellite instability (MSI-H) and BRAF mutations. However, no study to date has evaluated the relationship between p21 expression and CIMP in colorectal cancer. The purpose of this study was to examine the inter-relationships between p21, p53, CIMP, MSI and KRAS/BRAF status in colorectal cancer. We utilized 737 relatively unbiased samples of colorectal cancers from two large prospective cohort studies. Using quantitative real-time PCR (MethyLight), we measured DNA methylation in five CIMP-specific gene promoters [CACNA1G, CDKN2A (p16/INK4A), CRABP1, MLH1 and NEUROG1]. CIMP-high (>or=4/5 methylated promoters) was diagnosed in 118 (16%) of the 737 tumours. We also assessed expression of p21 and p53 by immunohistochemistry. Among the 737 tumours, 371 (50%) showed p21 loss. Both p21 loss and p53 positivity were inversely associated with CIMP-high, MSI-H and BRAF mutations. The associations of p21 with these molecular features were still present after tumours were stratified by p53 status. In contrast, the associations of p53 positivity with the molecular features were no longer present after tumours were stratified by p21 status. When CIMP-high and non-CIMP-high tumours were stratified by MSI or KRAS/BRAF status, CIMP-high and MSI-H (but not BRAF mutations) were still inversely associated with p21 loss. In conclusion, down-regulation of p21 is inversely correlated with CIMP-high and MSI-H in colorectal cancer, independent of TP53 and BRAF status.

Structures of oncogenic, suppressor and rescued p53 core-domain variants: mechanisms of mutant p53 rescue

PubMed Central

Wallentine, Brad D.; Wang, Ying; Tretyachenko-Ladokhina, Vira; Tan, Martha; Senear, Donald F.; Luecke, Hartmut

2013-01-01

To gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53, X-ray crystallographic structures of four p53 core-domain variants were determined. These include an oncogenic mutant, V157F, two single-site suppressor mutants, N235K and N239Y, and the rescued cancer mutant V157F/N235K/N239Y. The V157F mutation substitutes a smaller hydrophobic valine with a larger hydrophobic phenylalanine within strand S4 of the hydrophobic core. The structure of this cancer mutant shows no gross structural changes in the overall fold of the p53 core domain, only minor rearrangements of side chains within the hydrophobic core of the protein. Based on biochemical analysis, these small local perturbations induce instability in the protein, increasing the free energy by 3.6 kcal mol−1 (15.1 kJ mol−1). Further biochemical evidence shows that each suppressor mutation, N235K or N239Y, acts individually to restore thermodynamic stability to V157F and that both together are more effective than either alone. All rescued mutants were found to have wild-type DNA-binding activity when assessed at a permissive temperature, thus pointing to thermodynamic stability as the critical underlying variable. Interestingly, thermodynamic analysis shows that while N239Y demonstrates stabilization of the wild-type p53 core domain, N235K does not. These observations suggest distinct structural mechanisms of rescue. A new salt bridge between Lys235 and Glu198, found in both the N235K and rescued cancer mutant structures, suggests a rescue mechanism that relies on stabilizing the β-sandwich scaffold. On the other hand, the substitution N239Y creates an advantageous hydrophobic contact between the aromatic ring of this tyrosine and the adjacent Leu137. Surprisingly, the rescued cancer mutant shows much larger structural deviations than the cancer mutant alone when compared with wild-type p53. These suppressor mutations appear to rescue p53 function by creating novel intradomain interactions that stabilize the core domain, allowing compensation for the destabilizing V157F mutation. PMID:24100332

Histopathologic features of ovarian borderline tumors are not predictive of clinical outcome.

PubMed

Avril, Stefanie; Hahn, Ellen; Specht, Katja; Hauptmann, Steffen; Höss, Cornelia; Kiechle, Marion; Höfler, Heinz; Schmalfeldt, Barbara

2012-12-01

Ovarian borderline tumors (BOTs) generally have an excellent prognosis, although recurrences and malignant transformation can occur. Our aim was to compare clinicopathologic features of BOT with clinical outcome. In seventy consecutive BOTs clinicopathologic parameters, tumor cell proliferation (Ki67) and in selected cases KRAS, BRAF and p53 mutational status were analyzed with recurrence-free and overall survival as the endpoints. Sixty-one (87%) patients presented with FIGO stage I, 3 stage II, and 6 stage III. Thirty-four patients had serous and 36 mucinous BOT (30 intestinal and 6 endocervical subtypes). Non-invasive peritoneal implants occurred in 9 patients, and no invasive implants were observed. Recurrence-free and overall survival rates were 91% and 99%, respectively, at a mean follow-up of 63 months. Disease recurrence occurred in 6 cases (all FIGO stage I) including 3 serous, 1 mucinous-intestinal, and 2 mucinous-endocervical subtypes. Mean time to recurrence was 27 months (range 8-68). The recurrence rate following fertility-conserving surgery was 31% (5/16) compared to 2% (1/54) after bilateral salpingo-oophorectomy. Neither peritoneal implants (9/70), micropapillary pattern (2/34), microinvasion (4/70), nor increased tumor cell proliferation was associated with a higher recurrence rate. The frequency of KRAS or BRAF mutations was 50% (3/6 recurrences and 3/6 controls; 4 KRAS, 2 BRAF mutations). No p53 mutations (0/12) were detected in primary or recurrent BOTs. Histopathologic parameters were not predictive of BOT recurrence including previously suggested risk factors such as micropapillary pattern and microinvasion. However, fertility-conserving surgery and incomplete surgical staging were associated with a higher risk for recurrence. Copyright © 2012 Elsevier B.V. All rights reserved.

TP53 mutations in myelodysplastic syndrome are strongly correlated with aberrations of chromosome 5, and correlate with adverse prognosis.

PubMed

Kulasekararaj, Austin G; Smith, Alexander E; Mian, Syed A; Mohamedali, Azim M; Krishnamurthy, Pramila; Lea, Nicholas C; Gäken, Joop; Pennaneach, Coralie; Ireland, Robin; Czepulkowski, Barbara; Pomplun, Sabine; Marsh, Judith C; Mufti, Ghulam J

2013-03-01

This study aimed to determine the incidence/prognostic impact of TP53 mutation in 318 myelodysplastic syndrome (MDS) patients, and to correlate the changes to cytogenetics, single nucleotide polymorphism array karyotyping and clinical outcome. The median age was 65 years (17-89 years) and median follow-up was 45 months [95% confidence interval (CI) 27-62 months]. TP53 mutations occurred in 30 (9.4%) patients, exclusively in isolated del5q (19%) and complex karyotype (CK) with -5/5q-(72%), correlated with International Prognostic Scoring System intermediate-2/high, TP53 protein expression, higher blast count and leukaemic progression. Patients with mutant TP53 had a paucity of mutations in other genes implicated in myeloid malignancies. Median overall survival of patients with TP53 mutation was shorter than wild-type (9 versus 66 months, P < 0.001) and it retained significance in multivariable model (Hazard Ratio 3.8, 95%CI 2.3-6.3,P < 0.001). None of the sequentially analysed samples showed a disappearance of the mutant clone or emergence of new clones, suggesting an early occurrence of TP53 mutations. A reduction in mutant clone correlated with response to 5-azacitidine, however clones increased in non-responders and persisted at relapse. The adverse impact of TP53 persists after adjustment for cytogenetic risk and is of practical importance in evaluating prognosis. The relatively common occurrence of these mutations in two different prognostic spectrums of MDS, i.e. isolated 5q- and CK with -5/5q-, possibly implies two different mechanistic roles for TP53 protein. © 2013 Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

p14(ARF) nuclear overexpression in aggressive B-cell lymphomas is a sensor of malfunction of the common tumor suppressor pathways.

PubMed

Sánchez-Aguilera, Abel; Sánchez-Beato, Margarita; García, Juan F; Prieto, Ignacio; Pollan, Marina; Piris, Miguel A

2002-02-15

p14(ARF), the alternative product from the human INK4a/ARF locus, antagonizes Hdm2 and mediates p53 activation in response to oncogenic stimuli. An immunohistochemical study of p14(ARF) expression in 74 samples of aggressive B-cell lymphomas was performed, demonstrating an array of different abnormalities. A distinct nucleolar expression pattern was detected in nontumoral tissue and a subset of lymphomas (50/74). In contrast, a group of cases (8/74) showed absence of p14(ARF) expression, dependent either on promoter hypermethylation or gene loss. Additionally, 16 out of 74 cases displayed an abnormal nuclear p14(ARF) overexpression not confined to the nucleoli, as confirmed by confocal microscopy, and that was associated with high levels of p53 and Hdm2. A genetic study of these cases failed to show any alteration in the p14(ARF) gene, but revealed the presence of p53 mutations in over 50% of these cases. An increased growth fraction and a more aggressive clinical course, with a shortened survival time, also characterized the group of tumors with p14(ARF) nuclear overexpression. Moreover, this p14(ARF) expression pattern was more frequent in tumors displaying accumulated alterations in the p53, p16(INK4a), and p27(KIP1) tumor supressors. These observations, together with the consideration of the central role of p14(ARF) in cell cycle control, suggest that p14(ARF) abnormal nuclear overexpression is a sensor of malfunction of the major cell cycle regulatory pathways, and consequently a marker of a high tumor aggressivity.

Genes with mutation significance were highly associated with the clinical pattern of patients with breast cancer.

PubMed

Ding, Wan-Jun; Zeng, Tao; Wang, Li-Jun; Lei, Hong-Bo; Ge, Wei; Wang, Zhi

2017-11-17

In the United States, breast cancer is the second leading cause of cancer death in women. Over the past 20 years, breast cancer incidence and mortality rates increased rapidly in developing regions. We aimed to identify the gene mutation patterns that associated with the clinical patterns, including survival status, histo-pathological classes and so forth, of breast cancer. We retrieved 1098 cases of the clinical information, and level-3 legacy data of mRNA expression level, protein expression data and mutation files from GDC data portal. The genes with mutation significance were obtained. We studied the impacts of mutation types on the expression levels of mRNA and protein. Different statistics methods were used to calculate the correlation between the mutation types and the expression data or histo-clinical measures. There were 24 genes with mutation significance identified. The most mutated genes were selected to study the role of specific mutations played on the patients with breast cancer. One interesting finding was the missense mutations on TP53 were related with high expression levels of mRNA and protein. The missense mutations on TP53 were highly related with the morphology, race, ER status, PR status and HER2 Status, while the truncated mutations were only related with the morphology, ER status and PR status. The missense mutation on PIK3CA was highly associated with the morphology, race, ER status and PR status. The mutants with different mutants and the wild type of the most mutated genes had different impacts on the histo-clinical measures that might help personalized therapy.

Influence of p53 status on the effects of boron neutron capture therapy in glioblastoma.

PubMed

Seki, Keiko; Kinashi, Yuko; Takahashi, Sentaro

2015-01-01

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

Establishment of a dog model for the p53 family pathway and identification of a novel isoform of p21 cyclin-dependent kinase inhibitor

PubMed Central

Zhang, Jin; Chen, Xiangling; Kent, Michael S.; Rodriguez, Carlos O.; Chen, Xinbin

2009-01-01

Spontaneous tumors in the dog offer a unique opportunity as models to study human cancer etiology and therapy. p53, the most commonly mutated gene in human cancers, is found to be altered in dog cancers. However, little is known about the role of p53 in dog tumorigenesis. Here, we found that upon exposure to DNA damage agents or Mdm2 inhibitor nutlin-3, canine p53 is accumulated and capable of inducing its target genes, MDM2 and p21. We also found that upon DNA damage, canine p53 is accumulated in the nucleus, followed by MDM2 nuclear translocation and increased 53BP1 foci formation. In addition, we found that canine p63 and p73 are up-regulated by DNA damage agents. Furthermore, colony formation assay showed that canine tumor cells are sensitive to DNA damage agents and nutlin-3 in a p53-dependent manner. Surprisingly, canine p21 is expressed as two isoforms. Thus, we generated multiple canine p21 mutants and found that aa 129 to 142 is required, whereas aa 139 is one of the key determinants, for two p21 isoform expression. Finally, we showed that although the full-length human p21 cDNA expresses one polypeptide, aa 139 appears to play a similar role as that in canine p21 for various migration patterns. Taken together, our results indicate that canine p53 family proteins have biological activities similar to human counterparts. These similarities make the dog as an excellent out-bred spontaneous tumor model and the dog can serve as a translation model from bench-top to cage-side and then to bed-side. PMID:19147538

Depletion of pro-oncogenic RUNX2 enhances gemcitabine (GEM) sensitivity of p53-mutated pancreatic cancer Panc-1 cells through the induction of pro-apoptotic TAp63.

PubMed

Ozaki, Toshinori; Nakamura, Mizuyo; Ogata, Takehiro; Sang, Meijie; Yoda, Hiroyuki; Hiraoka, Kiriko; Sang, Meixiang; Shimozato, Osamu

2016-11-01

Recently, we have described that siRNA-mediated silencing of runt-related transcription factor 2 (RUNX2) improves anti-cancer drug gemcitabine (GEM) sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells through the augmentation of p53 family TAp63-dependent cell death pathway. In this manuscript, we have extended our study to p53-mutated human pancreatic cancer Panc-1 cells. According to our present results, knockdown of mutant p53 alone had a marginal effect on GEM-mediated cell death of Panc-1 cells. We then sought to deplete RUNX2 using siRNA in Panc-1 cells and examined its effect on GEM sensitivity. Under our experimental conditions, RUNX2 knockdown caused a significant enhancement of GEM sensitivity of Panc-1 cells. Notably, GEM-mediated induction of TAp63 but not of TAp73 was further stimulated in RUNX2-depleted Panc-1 cells, indicating that, like AsPC-1 cells, TAp63 might play a pivotal role in the regulation of GEM sensitivity of Panc-1 cells. Consistent with this notion, forced expression of TAp63α in Panc-1 cells promoted cell cycle arrest and/or cell death, and massively increased luciferase activities driven by TAp63-target gene promoters such as p21WAF1 and NOXA. In addition, immunoprecipitation experiments indicated that RUNX2 forms a complex with TAp63 in Panc-1 cells. Taken together, our current observations strongly suggest that depletion of RUNX2 enhances the cytotoxic effect of GEM on p53-mutated Panc-1 cells through the stimulation of TAp63-dependent cell death pathway even in the presence of a large amount of pro-oncogenic mutant p53, and might provide an attractive strategy to treat pancreatic cancer patients with p53 mutations.

Depletion of pro-oncogenic RUNX2 enhances gemcitabine (GEM) sensitivity of p53-mutated pancreatic cancer Panc-1 cells through the induction of pro-apoptotic TAp63

PubMed Central

Ozaki, Toshinori; Nakamura, Mizuyo; Ogata, Takehiro; Sang, Meijie; Yoda, Hiroyuki; Hiraoka, Kiriko; Sang, Meixiang; Shimozato, Osamu

2016-01-01

Recently, we have described that siRNA-mediated silencing of runt-related transcription factor 2 (RUNX2) improves anti-cancer drug gemcitabine (GEM) sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells through the augmentation of p53 family TAp63-dependent cell death pathway. In this manuscript, we have extended our study to p53-mutated human pancreatic cancer Panc-1 cells. According to our present results, knockdown of mutant p53 alone had a marginal effect on GEM-mediated cell death of Panc-1 cells. We then sought to deplete RUNX2 using siRNA in Panc-1 cells and examined its effect on GEM sensitivity. Under our experimental conditions, RUNX2 knockdown caused a significant enhancement of GEM sensitivity of Panc-1 cells. Notably, GEM-mediated induction of TAp63 but not of TAp73 was further stimulated in RUNX2-depleted Panc-1 cells, indicating that, like AsPC-1 cells, TAp63 might play a pivotal role in the regulation of GEM sensitivity of Panc-1 cells. Consistent with this notion, forced expression of TAp63α in Panc-1 cells promoted cell cycle arrest and/or cell death, and massively increased luciferase activities driven by TAp63-target gene promoters such as p21WAF1 and NOXA. In addition, immunoprecipitation experiments indicated that RUNX2 forms a complex with TAp63 in Panc-1 cells. Taken together, our current observations strongly suggest that depletion of RUNX2 enhances the cytotoxic effect of GEM on p53-mutated Panc-1 cells through the stimulation of TAp63-dependent cell death pathway even in the presence of a large amount of pro-oncogenic mutant p53, and might provide an attractive strategy to treat pancreatic cancer patients with p53 mutations. PMID:27713122

Anti-p53 antibodies in sera from patients with chronic obstructive pulmonary disease can predate a diagnosis of cancer.

PubMed

Trivers, G E; De Benedetti, V M; Cawley, H L; Caron, G; Harrington, A M; Bennett, W P; Jett, J R; Colby, T V; Tazelaar, H; Pairolero, P; Miller, R D; Harris, C C

1996-10-01

Serum anti-p53 antibodies (p53-Abs) may be surrogate markers for both p53 alterations and preclinical cancer. Ancillary to a prospective trial to abate progressive development of clinical stages of chronic obstructive pulmonary disease, we conducted a retrospective, nested case-control study. Twenty-three cases were diagnosed with cancer during the trial. Enzyme immunoassay, immunoblotting, and immunoprecipitation were used to detect p53-Abs in serum, immunohistochemistry (IHC) to detect p53 accumulation, and single-strand conformation polymorphism and DNA sequencing to detect p53 mutations in tumor samples. p53-Abs were detected by three types of assays in five (23%) of the cancer patients, 80% of whom had detectable p53-Abs before diagnosis: 2 lung cancers (7 and 6 months before), 1 prostate cancer (11 months), and 1 breast cancer (5 months). Four Ab-positive patients had IHC-positive tumors. Two of 4 Ab-positive patients and 2 of 14 Ab-negative had p53 missense mutations or base pair deletion and IHC-positive tumors. The 44 noncancer COPD controls, matched with the cancer cases for age, gender, and smoking habits, were negative for p53-Abs. These results indicate that p53-Abs may facilitate the early diagnosis of cancer in a subset of smokers with chronic obstructive pulmonary disease who are at an increased cancer risk.

p53 mutation, but not in vitro predictor genes of therapeutic efficacy of cisplatin, is clinically relevant in comparing partial and complete responder cases of maxillary squamous cell carcinoma.

PubMed

Kudo, Itsuhiro; Esumi, Mariko; Kida, Akihiro; Ikeda, Minoru

2010-10-01

To predict the efficacy of cisplatin and radiation therapy for maxillary squamous cell carcinoma, we examined the mRNA expression of 14 cisplatin-resistant genes and p53 mutation in specimens biopsied from patients prior to initiation of therapy. Five of 10 patients had mutations in the p53 gene, of whom four had residual tumors pathologically following chemoradiotherapy (p=0.0476). Of 14 genes examined, the mRNA expression of ATP7B was significantly lower in cases that were resistant to chemoradiotherapy. Six genes including multidrug resistance protein 1 (MDR-1), multidrug resistance associated protein 1 (MRP-1), Cu++ transporting, beta polypeptide (ATP7B), xeroderma pigmentosum, complementation group A (XPA), excision repair cross-complementing rodent repair deficiency, complementation group 1 (ERCC-1) and B-cell CLL/lymphoma 2 (BCL2) were down-regulated in cases of recurrent cancers. These results show that the evaluation of p53 mutation provides the most useful predictor of therapeutic effects. In responder cases, the drug-resistant genes that were determined in cell lines by culture do not necessarily translate into clinical relevance.

MDM2 and CDK4 amplifications are rare events in salivary duct carcinomas

PubMed Central

Grünewald, Inga; Trautmann, Marcel; Busch, Alina; Bauer, Larissa; Huss, Sebastian; Schweinshaupt, Petra; Vollbrecht, Claudia; Odenthal, Margarete; Quaas, Alexander; Büttner, Reinhard; Meyer, Moritz F.; Beutner, Dirk; Hüttenbrink, Karl-Bernd; Wardelmann, Eva; Stenner, Markus; Hartmann, Wolfgang

2016-01-01

Salivary duct carcinoma (SDC) is an aggressive adenocarcinoma of the salivary glands associated with poor clinical outcome. SDCs are known to carry TP53 mutations in about 50%, however, only little is known about alternative pathogenic mechanisms within the p53 regulatory network. Particularly, data on alterations of the oncogenes MDM2 and CDK4 located in the chromosomal region 12q13-15 are limited in SDC, while genomic rearrangements of the adjacent HMGA2 gene locus are well documented in subsets of SDCs. We here analyzed the mutational status of the TP53 gene, genomic amplification of MDM2, CDK4 and HMGA2 rearrangement/amplification as well as protein expression of TP53 (p53), MDM2 and CDK4 in 51 de novo and ex pleomorphic adenoma SDCs. 25 of 51 cases were found to carry TP53 mutations, associated with extreme positive immunohistochemical p53 staining levels in 13 cases. Three out of 51 tumors had an MDM2 amplification, one of them coinciding with a CDK4 amplification and two with a HMGA2 rearrangement/amplification. Two of the MDM2 amplifications occurred in the setting of a TP53 mutation. Two out of 51 cases showed a CDK4 amplification, one synchronously being MDM2 amplified and the other one displaying concurrent low copy number increases of both, MDM2 and HMGA2. In summary, we here show that subgroups of SDCs display genomic amplifications of MDM2 and/or CDK4, partly in association with TP53 mutations and rearrangement/amplification of HMGA2. Further research is necessary to clarify the role of chromosomal region 12q13-15 alterations in SDC tumorigenesis and their potential prognostic and therapeutic relevance. PMID:27662657

MDM2 and CDK4 amplifications are rare events in salivary duct carcinomas.

PubMed

Grünewald, Inga; Trautmann, Marcel; Busch, Alina; Bauer, Larissa; Huss, Sebastian; Schweinshaupt, Petra; Vollbrecht, Claudia; Odenthal, Margarete; Quaas, Alexander; Büttner, Reinhard; Meyer, Moritz F; Beutner, Dirk; Hüttenbrink, Karl-Bernd; Wardelmann, Eva; Stenner, Markus; Hartmann, Wolfgang

2016-11-15

Salivary duct carcinoma (SDC) is an aggressive adenocarcinoma of the salivary glands associated with poor clinical outcome. SDCs are known to carry TP53 mutations in about 50%, however, only little is known about alternative pathogenic mechanisms within the p53 regulatory network. Particularly, data on alterations of the oncogenes MDM2 and CDK4 located in the chromosomal region 12q13-15 are limited in SDC, while genomic rearrangements of the adjacent HMGA2 gene locus are well documented in subsets of SDCs. We here analyzed the mutational status of the TP53 gene, genomic amplification of MDM2, CDK4 and HMGA2 rearrangement/amplification as well as protein expression of TP53 (p53), MDM2 and CDK4 in 51 de novo and ex pleomorphic adenoma SDCs.25 of 51 cases were found to carry TP53 mutations, associated with extreme positive immunohistochemical p53 staining levels in 13 cases. Three out of 51 tumors had an MDM2 amplification, one of them coinciding with a CDK4 amplification and two with a HMGA2 rearrangement/amplification. Two of the MDM2 amplifications occurred in the setting of a TP53 mutation. Two out of 51 cases showed a CDK4 amplification, one synchronously being MDM2 amplified and the other one displaying concurrent low copy number increases of both, MDM2 and HMGA2.In summary, we here show that subgroups of SDCs display genomic amplifications of MDM2 and/or CDK4, partly in association with TP53 mutations and rearrangement/amplification of HMGA2. Further research is necessary to clarify the role of chromosomal region 12q13-15 alterations in SDC tumorigenesis and their potential prognostic and therapeutic relevance.

Efficient generation of P53 biallelic knockout Diannan miniature pigs via TALENs and somatic cell nuclear transfer.

PubMed

Shen, Youfeng; Xu, Kaixiang; Yuan, Zaimei; Guo, Jianxiong; Zhao, Heng; Zhang, Xuezeng; Zhao, Lu; Qing, Yubo; Li, Honghui; Pan, Weirong; Jia, Baoyu; Zhao, Hong-Ye; Wei, Hong-Jiang

2017-11-03

Pigs have many features that make them attractive as biomedical models for various diseases, including cancer. P53 is an important tumor suppressor gene that exerts a central role in protecting cells from oncogenic transformation and is mutated in a large number of human cancers. P53 mutations occur in almost every type of tumor and in over 50% of all tumors. In a recent publication, pigs with a mutated P53 gene were generated that resulted in lymphoma and renal and osteogenic tumors. However, approximately 80% of human tumors have dysfunctional P53. A P53-deficient pig model is still required to elucidate. Transcription activator-like effector nucleases (TALENs) were designed to target porcine P53 exon 4. The targeting activity was evaluated using a luciferase SSA recombination assay. P53 biallelic knockout (KO) cell lines were established from single-cell colonies of fetal fibroblasts derived from Diannan miniature pigs followed by electroporation with TALENs plasmids. One cell line was selected as the donor cell line for somatic cell nuclear transfer (SCNT) for the generation of P53 KO pigs. P53 KO stillborn fetuses and living piglets were obtained. Gene typing of the collected cloned individuals was performed by T7EI assay and sequencing. Fibroblast cells from Diannan miniature piglets with a P53 biallelic knockout or wild type were analyzed for the P53 response to doxorubicin treatment by confocal microscopy and western blotting. The luciferase SSA recombination assay revealed that the targeting activities of the designed TALENs were 55.35-fold higher than those of the control. Eight cell lines (8/19) were mutated for P53, and five of them were biallelic knockouts. One of the biallelic knockout cell lines was selected as nuclear donor cells for SCNT. The cloned embryos were transferred into five recipient gilts, three of them becoming pregnant. Five live fetuses were obtained from one surrogate by caesarean section after 38 days of gestation for genotyping. Finally, six live piglets and one stillborn piglet were collected from two recipients by caesarean section. Sequencing analyses of the target site confirmed the P53 biallelic knockout in all fetuses and piglets, consistent with the genotype of the donor cells. The qPCR analysis showed that the expression of the P53 mRNA had significant reduction in various tissues of the knockout piglets. Furthermore, confocal microscopy and western blotting analyses demonstrated that the fibroblast cells of Diannan miniature piglets with a P53 biallelic knockout were defective in mediating DNA damage when incubated with doxorubicin. TALENs combined with SCNT was successfully used to generate P53 KO Diannan miniature pigs. Although these genetically engineered Diannan miniature pigs had no tumorigenic signs, the P53 gene was dysfunctional. We believe that these pigs will provide powerful new resources for preclinical oncology and basic cancer research.

The p53-reactivating small molecule RITA induces senescence in head and neck cancer cells.

PubMed

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

2014-01-01

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

p53 inhibits autophagy by interacting with the human ortholog of yeast Atg17, RB1CC1/FIP200.

PubMed

Morselli, Eugenia; Shen, Shensi; Ruckenstuhl, Christoph; Bauer, Maria Anna; Mariño, Guillermo; Galluzzi, Lorenzo; Criollo, Alfredo; Michaud, Mickael; Maiuri, Maria Chiara; Chano, Tokuhiro; Madeo, Frank; Kroemer, Guido

2011-08-15

The tumor suppressor protein p53 tonically suppresses autophagy when it is present in the cytoplasm. This effect is phylogenetically conserved from mammals to nematodes, and human p53 can inhibit autophagy in yeast, as we show here. Bioinformatic investigations of the p53 interactome in relationship to the autophagy-relevant protein network underscored the possible relevance of a direct molecular interaction between p53 and the mammalian ortholog of the essential yeast autophagy protein Atg17, namely RB1-inducible coiled-coil protein 1 (RB1CC1), also called FAK family kinase-interacting protein of 200 KDa (FIP200). Mutational analyses revealed that a single point mutation in p53 (K382R) abolished its capacity to inhibit autophagy upon transfection into p53-deficient human colon cancer or yeast cells. In conditions in which wild-type p53 co-immunoprecipitated with RB1CC1/FIP200, p53 (K382R) failed to do so, underscoring the importance of the physical interaction between these proteins for the control of autophagy. In conclusion, p53 regulates autophagy through a direct molecular interaction with RB1CC1/FIP200, a protein that is essential for the very apical step of autophagy initiation.

ALTERNATE PATHWAY TO LUNG CANCER INDICATED BY KRAS AND P53 MUTATIONS IN NONSMOKERS EXPOSED TO INDOOR SMOKY COAL EMISSIONS

EPA Science Inventory

Alternate Pathway to Lung Cancer Indicated by KRAS and P53 Mutations in Nonsmokers Exposed to Indoor Smoky Coal Emissions

Use of smoky coal in unvented homes in Xuan Wei County, Yunnan Province, China, is
associated with lung cancer among nonsmoking females. Such wome...

Mutant p53-associated myosin-X upregulation promotes breast cancer invasion and metastasis.

PubMed

Arjonen, Antti; Kaukonen, Riina; Mattila, Elina; Rouhi, Pegah; Högnäs, Gunilla; Sihto, Harri; Miller, Bryan W; Morton, Jennifer P; Bucher, Elmar; Taimen, Pekka; Virtakoivu, Reetta; Cao, Yihai; Sansom, Owen J; Joensuu, Heikki; Ivaska, Johanna

2014-03-01

Mutations of the tumor suppressor TP53 are present in many forms of human cancer and are associated with increased tumor cell invasion and metastasis. Several mechanisms have been identified for promoting dissemination of cancer cells with TP53 mutations, including increased targeting of integrins to the plasma membrane. Here, we demonstrate a role for the filopodia-inducing motor protein Myosin-X (Myo10) in mutant p53-driven cancer invasion. Analysis of gene expression profiles from 2 breast cancer data sets revealed that MYO10 was highly expressed in aggressive cancer subtypes. Myo10 was required for breast cancer cell invasion and dissemination in multiple cancer cell lines and murine models of cancer metastasis. Evaluation of a Myo10 mutant without the integrin-binding domain revealed that the ability of Myo10 to transport β₁ integrins to the filopodia tip is required for invasion. Introduction of mutant p53 promoted Myo10 expression in cancer cells and pancreatic ductal adenocarcinoma in mice, whereas suppression of endogenous mutant p53 attenuated Myo10 levels and cell invasion. In clinical breast carcinomas, Myo10 was predominantly expressed at the invasive edges and correlated with the presence of TP53 mutations and poor prognosis. These data indicate that Myo10 upregulation in mutant p53-driven cancers is necessary for invasion and that plasma-membrane protrusions, such as filopodia, may serve as specialized metastatic engines.

Expression profiling of cutaneous squamous cell carcinoma with perineural invasion implicates the p53 pathway in the process.

PubMed

Warren, Timothy A; Broit, Natasa; Simmons, Jacinta L; Pierce, Carly J; Chawla, Sharad; Lambie, Duncan L J; Quagliotto, Gary; Brown, Ian S; Parsons, Peter G; Panizza, Benedict J; Boyle, Glen M

2016-09-26

Squamous cell carcinoma (SCC) is the second most common cancer worldwide and accounts for approximately 30% of all keratinocyte cancers. The vast majority of cutaneous SCCs of the head and neck (cSCCHN) are readily curable with surgery and/or radiotherapy unless high-risk features are present. Perineural invasion (PNI) is recognized as one of these high-risk features. The molecular changes during clinical PNI in cSCCHN have not been previously investigated. In this study, we assessed the global gene expression differences between cSCCHN with or without incidental or clinical PNI. The results of the analysis showed signatures of gene expression representative of activation of p53 in tumors with PNI compared to tumors without, amongst other alterations. Immunohistochemical staining of p53 showed cSCCHN with clinical PNI to be more likely to exhibit a diffuse over-expression pattern, with no tumors showing normal p53 staining. DNA sequencing of cSCCHN samples with clinical PNI showed no difference in mutation number or position with samples without PNI, however a significant difference was observed in regulators of p53 degradation, stability and activity. Our results therefore suggest that cSCCHN with clinical PNI may be more likely to contain alterations in the p53 pathway, compared to cSCCHN without PNI.

Mutations in histone modulators are associated with prolonged survival during azacitidine therapy

PubMed Central

Tobiasson, Magnus; McLornan, Donal P.; Karimi, Mohsen; Dimitriou, Marios; Jansson, Monika; Azenkoud, Asmaa Ben; Jädersten, Martin; Lindberg, Greger; Abdulkadir, Hani; Kulasekararaj, Austin; Ungerstedt, Johanna; Lennartsson, Andreas; Ekwall, Karl; Mufti, Ghulam J.; Hellström-Lindberg, Eva

2016-01-01

Early therapeutic decision-making is crucial in patients with higher-risk MDS. We evaluated the impact of clinical parameters and mutational profiles in 134 consecutive patients treated with azacitidine using a combined cohort from Karolinska University Hospital (n=89) and from King's College Hospital, London (n=45). While neither clinical parameters nor mutations had a significant impact on response rate, both karyotype and mutational profile were strongly associated with survival from the start of treatment. IPSS high-risk cytogenetics negatively impacted overall survival (median 20 vs 10 months; p<0.001), whereas mutations in histone modulators (ASXL1, EZH2) were associated with prolonged survival (22 vs 12 months, p=0.01). This positive association was present in both cohorts and remained highly significant in the multivariate cox model. Importantly, patients with mutations in histone modulators lacking high-risk cytogenetics showed a survival of 29 months compared to only 10 months in patients with the opposite pattern. While TP53 was negatively associated with survival, neither RUNX1-mutations nor the number of mutations appeared to influence survival in this cohort. We propose a model combining histone modulator mutational screening with cytogenetics in the clinical decision-making process for higher-risk MDS patients eligible for treatment with azacitidine. PMID:26959885

Mutant p53 protein in serum could be used as a molecular marker in human breast cancer.

PubMed

Balogh, G A; Mailo, D A; Corte, M M; Roncoroni, P; Nardi, H; Vincent, E; Martinez, D; Cafasso, M E; Frizza, A; Ponce, G; Vincent, E; Barutta, E; Lizarraga, P; Lizarraga, G; Monti, C; Paolillo, E; Vincent, R; Quatroquio, R; Grimi, C; Maturi, H; Aimale, M; Spinsanti, C; Montero, H; Santiago, J; Shulman, L; Rivadulla, M; Machiavelli, M; Salum, G; Cuevas, M A; Picolini, J; Gentili, A; Gentili, R; Mordoh, J

2006-04-01

p53 wild-type is a tumor suppressor gene involved in DNA gene transcription or DNA repair mechanisms. When damage to DNA is unrepairable, p53 induces programmed cell death (apoptosis). The mutant p53 gene is the most frequent molecular alteration in human cancer, including breast cancer. Here, we analyzed the genetic alterations in p53 oncogene expression in 55 patients with breast cancer at different stages and in 8 normal women. We measured by ELISA assay the serum levels of p53 mutant protein and p53 antibodies. Immunohistochemistry and RT-PCR using specific p53 primers as well as mutation detection by DNA sequencing were also evaluated in breast tumor tissue. Serological p53 antibody analysis detected 0/8 (0%), 0/4 (0%) and 9/55 (16.36%) positive cases in normal women, in patients with benign breast disease and in breast carcinoma, respectively. We found positive p53 mutant in the sera of 0/8 (0.0%) normal women, 0/4 (0%) with benign breast disease and 29/55 (52.72%) with breast carcinoma. Immunohistochemistry evaluation was positive in 29/55 (52.73%) with mammary carcinoma and 0/4 (0%) with benign breast disease. A very good correlation between p53 mutant protein detected in serum and p53 accumulation by immunohistochemistry (83.3% positive in both assays) was found in this study. These data suggest that detection of mutated p53 could be a useful serological marker for diagnostic purposes.

The heterozygous A53T mutation in the alpha-synuclein gene in a Chinese Han patient with Parkinson disease: case report and literature review.

PubMed

Xiong, Wei-Xi; Sun, Yi-Min; Guan, Rong-Yuan; Luo, Su-Shan; Chen, Chen; An, Yu; Wang, Jian; Wu, Jian-Jun

2016-10-01

The missense mutation A53T of alpha-synuclein gene (SNCA) was reported to be a rare but definite cause of sporadic and familial Parkinson disease (PD). It seemed to be restricted geographically in Greece and Italy. We aimed to identify the SNCA mutations in a Chinese PD cohort. Ninety-one early onset PD patients or familial PD probands were collected consecutively for the screening of PD-related genes. The genetic analysis was carried out by target sequencing of the exons and the corresponding flanking regions of the PD-related genes using Illumina HiSeq 2000 sequencer and further confirmed by Sanger sequencing or restriction fragment length polymorphism. Dosage mutations of exons in these genes were carried out by multiple ligation-dependent probe amplification. Among the 91 patients, we found only one heterozygous mutation of SNCA A53T, in a 23-year-old male patient with negative family history. The [(11)C]-2β-carbomethoxy-3β-(4-fluorophenyl) tropan (CFT) PET and PD-related spatial covariance pattern (PDRP) via [(18)F]-fluorodeoxyglucos (FDG) PET confirmed a typical pattern of PD. After examining his parents, we found his mother was an asymptomatic carrier, with declined hand dexterity detected by quantitative motor tests. Reduced dopamine transporter uptake of his mother was identified by CFT PET, and abnormal PDRP pattern was found by FDG PET. Our investigation expanded the clinical and genetic spectrum of Chinese PD patients, and we suggested SNCA mutations to be screened in familial and early onset Chinese PD patients.

Clinic and Functional Analysis of p73R1 Mutations in Prostate Cancer

DTIC Science & Technology

2006-02-01

sequence variants in Marfan syndrome and related connective tissue disorders. Genet Test 1:237-42. Matsuoka S, Huang M, Elledge SJ. 1998. Linkage of ATM... Syndrome (LFS; MIM# 151623), a highly penetrant familial cancer phenotype, usually associated with inherited mutations in TP53 (Bell, et al., 1999...TP53 (Table 1). Mutually exclusive mutations of CHEK2 and TP53 have been reported in patients with Li-Fraumeni syndrome (LFS) and also in patients

[Study on serum p53 protein in cops in Guangzhou city].

PubMed

Zhu, Wen-Chang; Chen, Qing; Chu, Xin-Wei; Luo, Chen-Ling; Wu, Min; Wang, Ya-Xian; Chen, Si-Dong

2003-10-01

Serum p53 protein overexpression was detected in population exposed to traffic exhaust gas to study the relation between traffic exhaust gas and the increased risk in p53 gene mutation. Serum p53 protein expression was measured by enzyme-linked immunosorbent assay. Relationship between different types of job and serum p53 protein overexpression were studied by pearson Chi-square tests. Results on serum p53 protein overexpression on jobs outside of office (5.74%) were not significantly higher than jobs inside the office. However, it suggested that traffic police men (12.12%) working outside of office, with whose length of service longer than 30 years had a significant overexpression of serum p53 protein than the others (5.36%) whose length of service was less than 30 years (P < 0.05, OR = 2.43, 95% CI: 1.11 - 5.33). Overexpression rate of p53 protein appeared to be 6.89% in the group whose average weekly exposure hours were more than 40 hours, which was significant higher than the group whose exposed hours were less than 40 hours (P < 0.05, OR = 1.71, 95% CI: 1.03 - 2.81). The result suggested that traffic exhaust gas was likely to cause mutation of p53 gene and increasing the incidence of lung cancer.

Detection of p53 mutations in proliferating vascular cells in glioblastoma multiforme.

PubMed

Kawasoe, Takuma; Takeshima, Hideo; Yamashita, Shinji; Mizuguchi, Sohei; Fukushima, Tsuyoshi; Yokogami, Kiyotaka; Yamasaki, Kouji

2015-02-01

Glioblastoma multiforme (GBM), one of the most aggressive tumors in humans, is highly angiogenic. However, treatment with the angiogenesis inhibitor bevacizumab has not significantly prolonged overall patient survival times. GBM resistance to angiogenesis inhibitors is attributed to multiple interacting mechanisms. Although mesenchymal transition via glioma stem-like cells has attracted attention, it is considered a poor biomarker. There is no simple method for differentiating tumor-derived and reactive vascular cells from normal cells. The authors attempted to detect the mesenchymal transition of tumor cells by means of p53 and isocitrate dehydrogenase 1 (IDH1) immunohistochemistry. Using antibody against p53 and IDH1 R132H, the authors immunohistochemically analyzed GBM tissue from patients who had undergone surgery at the University of Miyazaki Hospital during August 2005-December 2011. They focused on microvascular proliferation with a p53-positive ratio exceeding 50%. They compared TP53 mutations in original tumor tissues and in p53-positive and p53-negative microvascular proliferation cells collected by laser microdissection. Among 61 enrolled GBM patients, the first screening step (immunostaining) identified 46 GBMs as p53 positive, 3 of which manifested areas of prominent p53-positive microvascular proliferation (>50%). Histologically, areas of p53-positive microvascular proliferation tended to be clustered, and they coexisted with areas of p53-negative microvascular proliferation. Both types of microvascular proliferation cells were clearly separated from original tumor cells by glial fibrillary acidic protein, epidermal growth factor receptor, and low-/high-molecular-weight cytokeratin. DNA sequencing analysis disclosed that p53-positive microvascular proliferation cells exhibited TP53 mutations identical to those observed in the original tumor; p53-negative microvascular proliferation cells contained a normal allele. Although immunostaining indicated that 3 (2 primary and 1 secondary) of the 61 GBMs were positive for IDH1, no tumors contained microvascular proliferation cells positive for IDH1 R132H. Some microvascular proliferation clusters in GBM result from mesenchymal transition. The identification of useful markers might reveal this phenomenon as an infrequent event in GBMs.

Oral bacteria in pancreatic cancer: mutagenesis of the p53 tumour suppressor gene

PubMed Central

Öğrendik, Mesut

2015-01-01

Carcinoma of exocrine pancreas is the fourth leading cause of cancer deaths, worldwide. The prevalence of this disease is very high in patients with chronic pancreatitis. Orodigestive cancers are frequently seen in patients with periodontitis. These findings suggest that this type of cancer may have some bacterial origins. This study hypothesizes that the peptidyl arginine deaminase (PAD) enzymes found in oral bacteria may be responsible for the p53 point mutations that occur in patients with pancreatic cancer. Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Treponema denticola possess the PAD enzyme, and p53 arginine mutations have been detected in patients with pancreatic cancer. Moreover, the Pro allele p53Arg72-Pro is a risk factor for the development of this cancer. Anti-P. gingivalis antibody titers have been found to be higher in patients with pancreatic cancer as compared to healthy controls. The hypothesis in question can be tested if the DNA of P. gingivalis or the antibodies against P. gingivalis can be detected in patients with the p53 arginine mutation.If this hypothesis is true, it could reveal the real cause of pancreatic cancer, which is a fatal disease. Further studies are necessary in order to confirm this hypothesis. PMID:26617937

An in silico algorithm for identifying stabilizing pockets in proteins: test case, the Y220C mutant of the p53 tumor suppressor protein

PubMed Central

Bromley, Dennis; Bauer, Matthias R.; Fersht, Alan R.; Daggett, Valerie

2016-01-01

The p53 tumor suppressor protein performs a critical role in stimulating apoptosis and cell cycle arrest in response to oncogenic stress. The function of p53 can be compromised by mutation, leading to increased risk of cancer; approximately 50% of cancers are associated with mutations in the p53 gene, the majority of which are in the core DNA-binding domain. The Y220C mutation of p53, for example, destabilizes the core domain by 4 kcal/mol, leading to rapid denaturation and aggregation. The associated loss of tumor suppressor functionality is associated with approximately 75 000 new cancer cases every year. Destabilized p53 mutants can be ‘rescued’ and their function restored; binding of a small molecule into a pocket on the surface of mutant p53 can stabilize its wild-type structure and restore its function. Here, we describe an in silico algorithm for identifying potential rescue pockets, including the algorithm's integration with the Dynameomics molecular dynamics data warehouse and the DIVE visual analytics engine. We discuss the results of the application of the method to the Y220C p53 mutant, entailing finding a putative rescue pocket through MD simulations followed by an in silico search for stabilizing ligands that dock into the putative rescue pocket. The top three compounds from this search were tested experimentally and one of them bound in the pocket, as shown by nuclear magnetic resonance, and weakly stabilized the mutant. PMID:27503952

Periodontal Pathogens in the Etiology of Pancreatic Cancer.

PubMed

Öğrendik, Mesut

2017-03-01

Pancreatic cancer is the fourth leading cause of cancer-related deaths worldwide. Chronic pancreatitis is frequently observed in patients with pancreatic cancer, and a significant relationship between orodigestive cancer-related deaths and chronic periodontitis has been detected. Porphyromonas gingivalis , Tannerella forsythia , and Treponema denticola , collectively called the Red complex, are the major pathogens responsible for chronic periodontitis and secrete peptidylarginine deiminase. Anti- P. gingivalis antibodies titers are higher in pancreatic cancer patients than in healthy subjects. This review examines the association between oral bacteria and the etiology of pancreatic cancer. High rates of tumor suppressor gene p53 mutations, particularly p53 arginine mutations, were detected in pancreatic cancer patients. K-ras arginine mutations were detected in patients with pancreatic cancer. Oral bacteria peptidylarginine deiminases might lead to the p53 and K-ras point mutations by degrading arginine. Oral bacteria are likely to be responsible for the development of pancreatic cancer. If this hypothesis is true, it may reveal the real cause of pancreatic cancer, which is a fatal disease.

p53 regulates ERK1/2/CREB cascade via a novel SASH1/MAP2K2 crosstalk to induce hyperpigmentation.

PubMed

Zhou, Ding'an; Kuang, Zhongshu; Zeng, Xing; Wang, Ke; Ma, Jiangshu; Luo, Huangchao; Chen, Mei; Li, Yan; Zeng, Jiawei; Li, Shu; Luan, Fujun; He, Yong; Dai, Hongying; Liu, Beizhong; Li, Hui; He, Lin; Xing, Qinghe

2017-10-01

We previously reported that three point mutations in SASH1 and mutated SASH1 promote melanocyte migration in dyschromatosis universalis hereditaria (DUH) and a novel p53/POMC/Gαs/SASH1 autoregulatory positive feedback loop is regulated by SASH1 mutations to induce pathological hyperpigmentation phenotype. However, the underlying mechanism of molecular regulation to cause this hyperpigmentation disorder still remains unclear. In this study, we aimed to investigate the molecular mechanism undergirding hyperpigmentation in the dyschromatosis disorder. Our results revealed that SASH1 binds with MAP2K2 and is induced by p53-POMC-MC1R signal cascade to enhance the phosphorylation level of ERK1/2 and CREB. Moreover, increase in phosphorylated ERK1/2 and CREB levels and melanogenesis-specific molecules is induced by mutated SASH1 alleles. Together, our results suggest that a novel SASH1/MAP2K2 crosstalk connects ERK1/2/CREB cascade with p53-POMC-MC1R cascade to cause hyperpigmentation phenotype of DUH. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Mapping the Structural and Dynamical Features of Multiple p53 DNA Binding Domains: Insights into Loop 1 Intrinsic Dynamics

PubMed Central

Lukman, Suryani; Lane, David P.; Verma, Chandra S.

2013-01-01

The transcription factor p53 regulates cellular integrity in response to stress. p53 is mutated in more than half of cancerous cells, with a majority of the mutations localized to the DNA binding domain (DBD). In order to map the structural and dynamical features of the DBD, we carried out multiple copy molecular dynamics simulations (totaling 0.8 μs). Simulations show the loop 1 to be the most dynamic element among the DNA-contacting loops (loops 1-3). Loop 1 occupies two major conformational states: extended and recessed; the former but not the latter displays correlations in atomic fluctuations with those of loop 2 (~24 Å apart). Since loop 1 binds to the major groove whereas loop 2 binds to the minor groove of DNA, our results begin to provide some insight into the possible mechanism underpinning the cooperative nature of DBD binding to DNA. We propose (1) a novel mechanism underlying the dynamics of loop 1 and the possible tread-milling of p53 on DNA and (2) possible mutations on loop 1 residues to restore the transcriptional activity of an oncogenic mutation at a distant site. PMID:24324553

Mutational landscape of MCPyV-positive and MCPyV-negative Merkel cell carcinomas with implications for immunotherapy.

PubMed

Goh, Gerald; Walradt, Trent; Markarov, Vladimir; Blom, Astrid; Riaz, Nadeem; Doumani, Ryan; Stafstrom, Krista; Moshiri, Ata; Yelistratova, Lola; Levinsohn, Jonathan; Chan, Timothy A; Nghiem, Paul; Lifton, Richard P; Choi, Jaehyuk

2016-01-19

Merkel cell carcinoma (MCC) is a rare but highly aggressive cutaneous neuroendocrine carcinoma, associated with the Merkel cell polyomavirus (MCPyV) in 80% of cases. To define the genetic basis of MCCs, we performed exome sequencing of 49 MCCs. We show that MCPyV-negative MCCs have a high mutation burden (median of 1121 somatic single nucleotide variants (SSNVs) per-exome with frequent mutations in RB1 and TP53 and additional damaging mutations in genes in the chromatin modification (ASXL1, MLL2, and MLL3), JNK (MAP3K1 and TRAF7), and DNA-damage pathways (ATM, MSH2, and BRCA1). In contrast, MCPyV-positive MCCs harbor few SSNVs (median of 12.5 SSNVs/tumor) with none in the genes listed above. In both subgroups, there are rare cancer-promoting mutations predicted to activate the PI3K pathway (HRAS, KRAS, PIK3CA, PTEN, and TSC1) and to inactivate the Notch pathway (Notch1 and Notch2). TP53 mutations appear to be clinically relevant in virus-negative MCCs as 37% of these tumors harbor potentially targetable gain-of-function mutations in TP53 at p.R248 and p.P278. Moreover, TP53 mutational status predicts death in early stage MCC (5-year survival in TP53 mutant vs wild-type stage I and II MCCs is 20% vs. 92%, respectively; P = 0.0036). Lastly, we identified the tumor neoantigens in MCPyV-negative and MCPyV-positive MCCs. We found that virus-negative MCCs harbor more tumor neoantigens than melanomas or non-small cell lung cancers (median of 173, 65, and 111 neoantigens/sample, respectively), two cancers for which immune checkpoint blockade can produce durable clinical responses. Collectively, these data support the use of immunotherapies for virus-negative MCCs.

Distinct genetic profiles in colorectal tumors with or without the CpG island methylator phenotype

PubMed Central

Toyota, Minoru; Ohe-Toyota, Mutsumi; Ahuja, Nita; Issa, Jean-Pierre J.

2000-01-01

Colorectal cancers (CRCs) are characterized by multiple genetic (mutations) and epigenetic (CpG island methylation) alterations, but it is not known whether these evolve independently through stochastic processes. We have recently described a novel pathway termed CpG island methylator phenotype (CIMP) in CRC, which is characterized by the simultaneous methylation of multiple CpG islands, including several known genes, such as p16, hMLH1, and THBS1. We have now studied mutations in K-RAS, p53, DPC4, and TGFβRII in a panel of colorectal tumors with or without CIMP. We find that CIMP defines two groups of tumors with significantly different genetic lesions: frequent K-RAS mutations were found in CIMP+ CRCs (28/41, 68%) compared with CIMP− cases (14/47, 30%, P = 0.0005). By contrast, p53 mutations were found in 24% (10/41) of CIMP+ CRCs vs. 60% (30/46) of CIMP− cases (P = 0.002). Both of these differences were independent of microsatellite instability. These interactions between CIMP, K-RAS mutations, and p53 mutations were preserved in colorectal adenomas, suggesting that they occur early in carcinogenesis. The distinct combinations of epigenetic and genetic alterations in each group suggest that activation of oncogenes and inactivation of tumor suppressor genes is related to the underlying mechanism of generating molecular diversity in cancer, rather than simply accumulate stochastically during cancer development. PMID:10639144

Farewell to GBM-O: Genomic and transcriptomic profiling of glioblastoma with oligodendroglioma component reveals distinct molecular subgroups.

PubMed

Hinrichs, Benjamin H; Newman, Scott; Appin, Christina L; Dunn, William; Cooper, Lee; Pauly, Rini; Kowalski, Jeanne; Rossi, Michael R; Brat, Daniel J

2016-01-13

Glioblastoma with oligodendroglioma component (GBM-O) was recognized as a histologic pattern of glioblastoma (GBM) by the World Health Organization (WHO) in 2007 and is distinguished by the presence of oligodendroglioma-like differentiation. To better understand the genetic underpinnings of this morphologic entity, we performed a genome-wide, integrated copy number, mutational and transcriptomic analysis of eight (seven primary, primary secondary) cases. Three GBM-O samples had IDH1 (p.R132H) mutations; two of these also demonstrated 1p/19q co-deletion and had a proneural transcriptional profile, a molecular signature characteristic of oligodendroglioma. The additional IDH1 mutant tumor lacked 1p/19q co-deletion, harbored a TP53 mutation, and overall, demonstrated features most consistent with IDH mutant (secondary) GBM. Finally, five tumors were IDH wild-type (IDHwt) and had chromosome seven gains, chromosome 10 losses, and homozygous 9p deletions (CDKN2A), alterations typical of IDHwt (primary) GBM. IDHwt GBM-Os also demonstrated EGFR and PDGFRA amplifications, which correlated with classical and proneural expression subtypes, respectively. Our findings demonstrate that GBM-O is composed of three discrete molecular subgroups with characteristic mutations, copy number alterations and gene expression patterns. Despite displaying areas that morphologically resemble oligodendroglioma, the current results indicate that morphologically defined GBM-O does not correspond to a particular genetic signature, but rather represents a collection of genetically dissimilar entities. Ancillary testing, especially for IDH and 1p/19q, should be used for determining these molecular subtypes.

Genomic and Functional Approaches to Understanding Cancer Aneuploidy.

PubMed

Taylor, Alison M; Shih, Juliann; Ha, Gavin; Gao, Galen F; Zhang, Xiaoyang; Berger, Ashton C; Schumacher, Steven E; Wang, Chen; Hu, Hai; Liu, Jianfang; Lazar, Alexander J; Cherniack, Andrew D; Beroukhim, Rameen; Meyerson, Matthew

2018-04-09

Aneuploidy, whole chromosome or chromosome arm imbalance, is a near-universal characteristic of human cancers. In 10,522 cancer genomes from The Cancer Genome Atlas, aneuploidy was correlated with TP53 mutation, somatic mutation rate, and expression of proliferation genes. Aneuploidy was anti-correlated with expression of immune signaling genes, due to decreased leukocyte infiltrates in high-aneuploidy samples. Chromosome arm-level alterations show cancer-specific patterns, including loss of chromosome arm 3p in squamous cancers. We applied genome engineering to delete 3p in lung cells, causing decreased proliferation rescued in part by chromosome 3 duplication. This study defines genomic and phenotypic correlates of cancer aneuploidy and provides an experimental approach to study chromosome arm aneuploidy. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Oropharyngeal Squamous Cell Carcinoma Treated With Radiotherapy or Radiochemotherapy: Prognostic Role of TP53 and HPV Status

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

Fallai, Carlo, E-mail: carlo.fallai@istitutotumori.mi.i; Perrone, Federica; Licitra, Lisa

Purpose: To study the prognostic value of the TP53 mutation and human papilloma virus (HPV) status in oropharyngeal squamous cell carcinoma (OPSCC). Methods and materials: The TP53 mutation and HPV status were analyzed in 78 cases of locoregionally advanced OPSCC. The possible correlation of these factors with locoregiownal control, relapse-free survival, disease-specific survival, and overall survival (OS) was also investigated. Results: Of these 78 cases, 22 had disruptive and 22 had non-disruptive (silent) TP53 mutations; the remaining 34 cases had wild-type (WT) TP53. HPV 16 DNA was found in 9 cases (11%), but all HPV-positive (HPV+) cases carried a functionalmore » p53 protein, except for 1 case that had a silent mutation. HPV+ patients fared better than HPV-negative (HPV-) patients in terms of all survival parameters, with highly statistically significant differences between the groups. Specifically, no distant metastases were observed in the HPV+ patients, whereas they occurred in 17% of the HPV- patients. However, no difference was observed between the WT TP53 and mutation group, even when this was analyzed in terms of disruptive and non-disruptive mutations. Regardless, treatment with chemotherapy nearly doubled the 5-year OS rates, both in the mutation (42% vs. 22%) and WT (30 vs. 16%) group, but only the mutation group showed improvement in all survival parameters. In addition, the second tumor-free 5-year survival rate was 72% in HPV- cases, but no second tumors were observed in HPV+ and WT p53 cases. Conclusions: Patients with HPV+ OPSCC have an excellent prognosis after radiochemotherapy, but cisplatin-based chemotherapy may not confer a satisfactory outcome, especially in WT cases, thereby justifying the additional or alternative use of taxanes and epidermal growth factor receptors inhibitors. Uncommon distant metastases and second tumors in the HPV+ group may be cause for clinicians to review the follow-up policies in these patients.« less

Wip1 and p53 contribute to HTLV-1 Tax-induced tumorigenesis

PubMed Central

2012-01-01

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

The p53-Reactivating Small Molecule RITA Induces Senescence in Head and Neck Cancer Cells

PubMed Central

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

2014-01-01

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

A protein folding molecular imaging biosensor monitors the effects of drugs that restore mutant p53 structure and its downstream function in glioblastoma cells

PubMed Central

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

2018-01-01

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

Abrogation of Wip1 expression by RITA-activated p53 potentiates apoptosis induction via activation of ATM and inhibition of HdmX

PubMed Central

Spinnler, C; Hedström, E; Li, H; de Lange, J; Nikulenkov, F; Teunisse, A F A S; Verlaan-de Vries, M; Grinkevich, V; Jochemsen, A G; Selivanova, G

2011-01-01

Inactivation of the p53 tumour suppressor, either by mutation or by overexpression of its inhibitors Hdm2 and HdmX is the most frequent event in cancer. Reactivation of p53 by targeting Hdm2 and HdmX is therefore a promising strategy for therapy. However, Hdm2 inhibitors do not prevent inhibition of p53 by HdmX, which impedes p53-mediated apoptosis. Here, we show that p53 reactivation by the small molecule RITA leads to efficient HdmX degradation in tumour cell lines of different origin and in xenograft tumours in vivo. Notably, HdmX degradation occurs selectively in cancer cells, but not in non-transformed cells. We identified the inhibition of the wild-type p53-induced phosphatase 1 (Wip1) as the major mechanism important for full engagement of p53 activity accomplished by restoration of the ataxia telangiectasia mutated (ATM) kinase-signalling cascade, which leads to HdmX degradation. In contrast to previously reported transactivation of Wip1 by p53, we observed p53-dependent repression of Wip1 expression, which disrupts the negative feedback loop conferred by Wip1. Our study reveals that the depletion of both HdmX and Wip1 potentiates cell death due to sustained activation of p53. Thus, RITA is an example of a p53-reactivating drug that not only blocks Hdm2, but also inhibits two important negative regulators of p53 – HdmX and Wip1, leading to efficient elimination of tumour cells. PMID:21546907

Abrogation of Wip1 expression by RITA-activated p53 potentiates apoptosis induction via activation of ATM and inhibition of HdmX.

PubMed

Spinnler, C; Hedström, E; Li, H; de Lange, J; Nikulenkov, F; Teunisse, A F A S; Verlaan-de Vries, M; Grinkevich, V; Jochemsen, A G; Selivanova, G

2011-11-01

Inactivation of the p53 tumour suppressor, either by mutation or by overexpression of its inhibitors Hdm2 and HdmX is the most frequent event in cancer. Reactivation of p53 by targeting Hdm2 and HdmX is therefore a promising strategy for therapy. However, Hdm2 inhibitors do not prevent inhibition of p53 by HdmX, which impedes p53-mediated apoptosis. Here, we show that p53 reactivation by the small molecule RITA leads to efficient HdmX degradation in tumour cell lines of different origin and in xenograft tumours in vivo. Notably, HdmX degradation occurs selectively in cancer cells, but not in non-transformed cells. We identified the inhibition of the wild-type p53-induced phosphatase 1 (Wip1) as the major mechanism important for full engagement of p53 activity accomplished by restoration of the ataxia telangiectasia mutated (ATM) kinase-signalling cascade, which leads to HdmX degradation. In contrast to previously reported transactivation of Wip1 by p53, we observed p53-dependent repression of Wip1 expression, which disrupts the negative feedback loop conferred by Wip1. Our study reveals that the depletion of both HdmX and Wip1 potentiates cell death due to sustained activation of p53. Thus, RITA is an example of a p53-reactivating drug that not only blocks Hdm2, but also inhibits two important negative regulators of p53 - HdmX and Wip1, leading to efficient elimination of tumour cells.

P53 Suppression of Homologous Recombination and Tumorigenesis

DTIC Science & Technology

2012-01-01

mutation acted on both rad51 dependent gene conversion events and deletion events (6). Willers et al. also showed an increase in recombination...suffer from sarcomas. MEFs from these mice show aneuploidy, allelic loss and gene amplification. Most of these germline mutations are missense...the absence of tumor suppressor gene activity, such as p53, results in increased genomic instability and increased cancer predisposition

Using yeast to determine the functional consequences of mutations in the human p53 tumor suppressor gene: An introductory course-based undergraduate research experience in molecular and cell biology.

PubMed

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

2017-03-04

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

Using yeast to determine the functional consequences of mutations in the human p53 tumor suppressor gene: An introductory course‐based undergraduate research experience in molecular and cell biology

PubMed Central

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

2016-01-01

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

Functional census of mutation sequence spaces: The example of p53 cancer rescue mutants

PubMed Central

Danziger, Samuel A.; Swamidass, S. Joshua; Zeng, Jue; Dearth, Lawrence R.; Lu, Qiang; Chen, Jonathan H.; Cheng, Jainlin; Hoang, Vinh P.; Saigo, Hiroto; Luo, Ray; Baldi, Pierre; Brachmann, Rainer K.; Lathrop, Richard H.

2009-01-01

Many biomedical problems relate to mutant functional properties across a sequence space of interest, e.g., flu, cancer, and HIV. Detailed knowledge of mutant properties and function improves medical treatment and prevention. A functional census of p53 cancer rescue mutants would aid the search for cancer treatments from p53 rescue. We devised a general methodology for conducting a functional census of a mutation sequence space, and conducted a double-blind predictive test on the functional rescue property of 71 novel putative p53 cancer rescue mutants iteratively predicted in sets of 3. Double-blind predictive accuracy (15-point moving window) rose from 47% to 86% over the trial (r = 0.74). Code and data are available upon request1. PMID:17048398

Both germ line and somatic genetics of the p53 pathway affect ovarian cancer incidence and survival.

PubMed

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

2008-01-01

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

P53 Suppression of Homologous Recombination and Tumorigenesis

DTIC Science & Technology

2013-01-01

absence or mutation of p53 and the mechanism of p53 control of HR in an in vivo system. p53 is often a targeted therapy and further insight into the...function of p53 in DNA repair pathways can be vital to finding novel points of targeted therapy . Our data will add insight to the important paradigm...cancers. Cisplatin works by the aquation of a chloride ligand that results in the formation of a DNA adduct, usually crosslinking the DNA, which impedes

The electrostatic surface of MDM2 modulates the specificity of its interaction with phosphorylated and unphosphorylated p53 peptides.

PubMed

Brown, Christopher John; Srinivasan, Deepa; Jun, Lee Hui; Coomber, David; Verma, Chandra S; Lane, David P

2008-03-01

Florescence anisotropy measurements using FAM-labelled p53 peptides showed that the binding of the peptides to MDM2 was dependant upon the phosphorylation of p53 at Thr18 and that this binding was modulated by the electrostatic properties of MDM2. In agreement with computational predictions, the binding to phosphorylated p53 peptide, in comparison to the unphosphorylated p53 peptide, was enhanced upon mutation of 3 key residues on the MDM2 surface.

Genetics and Prognostication in Splenic Marginal Zone Lymphoma: Revelations from Deep Sequencing

PubMed Central

Gibson, Jane; Wang, Jun; Walewska, Renata; Parker, Helen; Parker, Anton; Davis, Zadie; Gardiner, Anne; McIver-Brown, Neil; Kalpadakis, Christina; Xochelli, Aliki; Anagnostopoulos, Achilles; Fazi, Claudia; de Castro, David Gonzalez; Dearden, Claire; Pratt, Guy; Rosenquist, Richard; Ashton-Key, Margaret; Forconi, Francesco; Collins, Andrew; Ghia, Paolo; Matutes, Estella; Pangalis, Gerassimos; Stamatopoulos, Kostas; Oscier, David; Strefford, Jonathan C

2015-01-01

Purpose Mounting evidence supports the clinical significance of gene mutations and immunogenetic features in common mature B-cell malignancies. Experimental Design We undertook a detailed characterization of the genetic background of splenic marginal zone lymphoma (SMZL), using targeted re-sequencing and explored potential clinical implications in a multinational cohort of 175 SMZL patients. Results We identified recurrent mutations in TP53 (16%), KLF2 (12%), NOTCH2 (10%), TNFAIP3 (7%), MLL2 (11%), MYD88 (7%) and ARID1A (6%), all genes known to be targeted by somatic mutation in SMZL. KLF2 mutations were early, clonal events, enriched in patients with del(7q) and IGHV1-2*04 B-cell receptor immunoglobulins, and were associated with a short median time-to-first-treatment (0.12 vs. 1.11 yrs; P=0.01). In multivariate analysis mutations in NOTCH2 (HR 2.12, 95%CI 1.02-4.4, P=0.044) and 100% germline IGHV gene identity (HR 2.19, 95%CI 1.05-4.55, P=0.036) were independent markers of short time-to-first-treatment, while TP53 mutations were an independent marker of short overall survival (HR 2.36, 95% CI 1.08-5.2, P=0.03). Conclusion We identify key associations between gene mutations and clinical outcome, demonstrating for the first time that NOTCH2 and TP53 gene mutations are independent markers of reduced treatment-free and overall survival, respectively. PMID:25779943

Targeting p53-MDM2-MDMX Loop for Cancer Therapy

PubMed Central

Zhang, Qi; Zeng, Shelya X.

2015-01-01

The tumor suppressor p53 plays a central role in anti-tumorigenesis and cancer therapy. It has been described as “the guardian of the genome”, because it is essential for conserving genomic stability by preventing mutation, and its mutation and inactivation are highly related to all human cancers. Two important p53 regulators, MDM2 and MDMX, inactivate p53 by directly inhibiting its transcriptional activity and mediating its ubiquitination in a feedback fashion, as their genes are also the transcriptional targets of p53. On account of the importance of the p53-MDM2- MDMX loop in the initiation and development of wild type p53-containing tumors, intensive studies over the past decade have been aiming to identify small molecules or peptides that could specifically target individual protein molecules of this pathway for developing better anti-cancer therapeutics. In this chapter, we review the approaches for screening and discovering efficient and selective MDM2 inhibitors with emphasis on the most advanced synthetic small molecules that interfere with the p53-MDM2 interaction and are currently on Phase I clinical trials. Other therapeutically useful strategies targeting this loop, which potentially improve the prospects of cancer therapy and prevention, will also be discussed briefly. PMID:25201201

Analysis of alterations of oncogenes and tumor suppressor genes in chronic lymphocytic leukemia.

PubMed Central

Gaidano, G.; Newcomb, E. W.; Gong, J. Z.; Tassi, V.; Neri, A.; Cortelezzi, A.; Calori, R.; Baldini, L.; Dalla-Favera, R.

1994-01-01

B cell chronic lymphocytic leukemia (B-CLL) represents the most frequent adult leukemia in the Western world. The molecular pathogenesis of B-CLL is largely unknown. Although initial reports on small panels of cases had suggested a role for Bcl-1 and Bcl-2 oncogene activation in B-CLL, later investigations failed to confirm these data. Among tumor suppressor genes, p53 mutations have been reported in a fraction of cases. In this study, we have attempted a conclusive definition of the involvement of dominantly acting oncogenes (Bcl-1 and Bcl-2) and tumor suppressor loci (p53, 6q-) in 100 cases of B-CLL selected for their CD5 positivity and Rai's stage (0 to IV). Rearrangements of Bcl-1 and Bcl-2 and deletions of 6q and 17p were analyzed by Southern blot using multiple probes. Mutational analysis (single strand conformation polymorphism and polymerase chain reaction direct sequencing) was used to assay p53 inactivation. No alterations of Bcl-1 or Bcl-2 were detected in the 100 cases tested. Mutations of p53 were found in 10/100 cases without any significant association with clinical stage. Deletions of 6q were present in 4/100 cases. Overall, our data indicate that: 1) contrary to previous reports, Bcl-1 and Bcl-2 rearrangements are not involved in CD5+ B-CLL pathogenesis and 2) p53 mutations are present in 10% of cases at all stages of the disease. Images Figure 1 Figure 2 Figure 3 PMID:8203469

Heterozygous inactivation of tsc2 enhances tumorigenesis in p53 mutant zebrafish

PubMed Central

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

2013-01-01

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

The role of HPV RNA transcription, immune response-related gene expression and disruptive TP53 mutations in diagnostic and prognostic profiling of head and neck cancer.

PubMed

Wichmann, Gunnar; Rosolowski, Maciej; Krohn, Knut; Kreuz, Markus; Boehm, Andreas; Reiche, Anett; Scharrer, Ulrike; Halama, Dirk; Bertolini, Julia; Bauer, Ulrike; Holzinger, Dana; Pawlita, Michael; Hess, Jochen; Engel, Christoph; Hasenclever, Dirk; Scholz, Markus; Ahnert, Peter; Kirsten, Holger; Hemprich, Alexander; Wittekind, Christian; Herbarth, Olf; Horn, Friedemann; Dietz, Andreas; Loeffler, Markus

2015-12-15

Stratification of head and neck squamous cell carcinomas (HNSCC) based on HPV16 DNA and RNA status, gene expression patterns, and mutated candidate genes may facilitate patient treatment decision. We characterize head and neck squamous cell carcinomas (HNSCC) with different HPV16 DNA and RNA (E6*I) status from 290 consecutively recruited patients by gene expression profiling and targeted sequencing of 50 genes. We show that tumors with transcriptionally inactive HPV16 (DNA+ RNA-) are similar to HPV-negative (DNA-) tumors regarding gene expression and frequency of TP53 mutations (47%, 8/17 and 43%, 72/167, respectively). We also find that an immune response-related gene expression cluster is associated with lymph node metastasis, independent of HPV16 status and that disruptive TP53 mutations are associated with lymph node metastasis in HPV16 DNA- tumors. We validate each of these associations in another large data set. Four gene expression clusters which we identify differ moderately but significantly in overall survival. Our findings underscore the importance of measuring the HPV16 RNA (E6*I) and TP53-mutation status for patient stratification and identify associations of an immune response-related gene expression cluster and TP53 mutations with lymph node metastasis in HNSCC. © 2015 UICC.

A novel natural killer cell line (KHYG-1) from a patient with aggressive natural killer cell leukemia carrying a p53 point mutation.

PubMed

Yagita, M; Huang, C L; Umehara, H; Matsuo, Y; Tabata, R; Miyake, M; Konaka, Y; Takatsuki, K

2000-05-01

We present the establishment of a natural killer (NK) leukemia cell line, designated KHYG-1, from the blood of a patient with aggressive NK leukemia, which both possessed the same p53 point mutation. The immunophenotype of the primary leukemia cells was CD2+, surface CD3-, cytoplasmic CD3epsilon+, CD7+, CD8alphaalpha+, CD16+, CD56+, CD57+ and HLA-DR+. A new cell line (KHYG-1) was established by culturing peripheral leukemia cells with 100 units of recombinant interleukin (IL)-2. The KHYG-1 cells showed LGL morphology with a large nucleus, coarse chromatin, conspicuous nucleoli, and abundant basophilic cytoplasm with many azurophilic granules. The immunophenotype of KHYG-1 cells was CD1-, CD2+, surface CD3-, cytoplasmic CD3epsilon+, CD7+, CD8alphaalpha+, CD16-, CD25-, CD33+, CD34-, CD56+, CD57-, CD122+, CD132+, and TdT-. Southern blot analysis of these cells revealed a normal germline configuration for the beta, delta, and gamma chains of the T cell receptor and the immunoglobulin heavy-chain genes. Moreover, the KHYG-1 cells displayed NK cell activity and IL-2-dependent proliferation in vitro, suggesting that they are of NK cell origin. Epstein-Barr virus (EBV) DNA was not detected in KHYG-1 cells by Southern blot analysis with a terminal repeat probe from an EBV genome. A point mutation in exon 7 of the p53 gene was detected in the KHYG-1 cells by PCR/SSCP analysis, and direct sequencing revealed the conversion of C to T at nucleotide 877 in codon 248. The primary leukemia cells also carried the same point mutation. Although the precise role of the p53 point mutation in leukemogenesis remains to be clarified, the establishment of an NK leukemia cell line with a p53 point mutation could be valuable in the study of leukemogenesis.

Aflatoxin B1-induced DNA adduct formation and p53 mutations in CYP450-expressing human liver cell lines.

PubMed

Macé, K; Aguilar, F; Wang, J S; Vautravers, P; Gómez-Lechón, M; Gonzalez, F J; Groopman, J; Harris, C C; Pfeifer, A M

1997-07-01

Epidemiological evidence has been supporting a relationship between dietary aflatoxin B1 (AFB1) exposure, development of human primary hepatocellular carcinoma (HCC) and mutations in the p53 tumor suppressor gene. However, the correlation between the observed p53 mutations, the AFB1 DNA adducts and their activation pathways has not been elucidated. Development of relevant cellular in vitro models, taking into account species and tissue specificity, could significantly contribute to the knowledge of cytotoxicity and genotoxicity mechanisms of chemical procarcinogens, such as AFB1, in humans. For this purpose a non-tumorigenic SV40-immortalized human liver epithelial cell line (THLE cells) which retained most of the phase II enzymes, but had markedly reduced phase I activities was used for stable expression of the human CYP1A2, CYP2A6, CYP2B6 and CYP3A4 cDNA. The four genetically engineered cell lines (T5-1A2, T5-2A6, T5-2B6 and T5-3A4) produced high levels of the specific CYP450 proteins and showed comparable or higher catalytic activities related to the CYP450 expression when compared to human hepatocytes. The T5-1A2, T5-2A6, T5-2B6 and T5-3A4 cell lines exhibited a very high sensitivity to the cytotoxic effects of AFB1 and were approximately 125-, 2-, 2- and 15-fold, respectively, more sensitive than the control T5-neo cells, transfected with an expressing vector which does not contain CYP450 cDNA. In the CYP450-expressing cells, nanomolar doses of AFB1-induced DNA adduct formation including AFB1-N7-guanine, -pyrimidyl and -diol adducts. In addition, the T5-1A2 cells showed AFM1-DNA adducts. At similar levels of total DNA adducts, both the T5-1A2 and T5-3A4 cells showed, at codon 249 of the p53 gene, AGG to AGT transversions at a relative frequency of 15x10(-6). In contrast, only the T5-3A4 cells showed CCC to ACC transversion at codon 250 at a high frequency, whereas the second most frequent mutations found in the T5-1A2 cells were C to T transitions at the first and second position of the codon 250. No significant AFB1-induced p53 mutations could be detected in the T5-2A6 cells. Therefore, the differential expression of specific CYP450 genes in human hepatocytes can modulate the cytotoxicity, DNA adduct levels and frequency of p53 mutations produced by AFB1.

p53 Dependent Centrosome Clustering Prevents Multipolar Mitosis in Tetraploid Cells

PubMed Central

Yi, Qiyi; Zhao, Xiaoyu; Huang, Yun; Ma, Tieliang; Zhang, Yingyin; Hou, Heli; Cooke, Howard J.; Yang, Da-Qing; Wu, Mian; Shi, Qinghua

2011-01-01

Background p53 abnormality and aneuploidy often coexist in human tumors, and tetraploidy is considered as an intermediate between normal diploidy and aneuploidy. The purpose of this study was to investigate whether and how p53 influences the transformation from tetraploidy to aneuploidy. Principal Findings Live cell imaging was performed to determine the fates and mitotic behaviors of several human and mouse tetraploid cells with different p53 status, and centrosome and spindle immunostaining was used to investigate centrosome behaviors. We found that p53 dominant-negative mutation, point mutation, or knockout led to a 2∼ 33-fold increase of multipolar mitosis in N/TERT1, 3T3 and mouse embryonic fibroblasts (MEFs), while mitotic entry and cell death were not significantly affected. In p53-/- tetraploid MEFs, the ability of centrosome clustering was compromised, while centrosome inactivation was not affected. Suppression of RhoA/ROCK activity by specific inhibitors in p53-/- tetraploid MEFs enhanced centrosome clustering, decreased multipolar mitosis from 38% to 20% and 16% for RhoA and ROCK, respectively, while expression of constitutively active RhoA in p53+/+ tetraploid 3T3 cells increased the frequency of multipolar mitosis from 15% to 35%. Conclusions p53 could not prevent tetraploid cells entering mitosis or induce tetraploid cell death. However, p53 abnormality impaired centrosome clustering and lead to multipolar mitosis in tetraploid cells by modulating the RhoA/ROCK signaling pathway. PMID:22076149

Cell-intrinsic determinants of ibrutinib-induced apoptosis in Chronic Lymphocytic Leukemia

PubMed Central

Amin, Nisar A.; Balasubramanian, Sriram; Saiya-Cork, Kamlai; Shedden, Kerby; Hu, Nan; Malek, Sami N.

2016-01-01

Purpose Ibrutinib, a Bruton’s tyrosine kinase (BTK) inhibitor, is approved for the treatment of relapsed CLL and CLL with del17p. Mechanistically, ibrutinib interferes with BCR signaling as well as multiple CLL cell to microenvironment interactions. Given the importance of ibrutinib in the management of CLL, a deeper understanding of factors governing sensitivity and resistance is warranted. Experimental Design We studied 48 longitudinally sampled paired CLL samples, 42 of which were procured before and after standard CLL chemotherapies, and characterized them for well-studied CLL molecular traits as well as by whole exome sequencing and SNP 6.0 array profiling. We exposed these samples to 0.25 μM – 5 μM of ibrutinib ex vivo and measured apoptosis fractions as well as BCR signaling by immunoblotting. We disrupted TP53 in HG3, PGA1 and PG-EBV cell lines and measured BCR signaling and ibrutinib responses. Results CLL samples demonstrated a surprisingly wide range of ex vivo sensitivities to ibrutinib with IC50 values ranging from 0.4 μM – 9.7 μM. Unmutated IGVH status, elevated ZAP70 expression and trisomy 12 were associated with heightened sensitivity to ibrutinib treatment. Five CLL samples were substantially more resistant to ibrutinib following relapse from chemotherapy; of these, three had acquired a del17p/TP53 mutated status. A validation sample of 15 CLL carrying TP53 mutations, of which 13 carried both del17p and a TP53 mutation confirmed substantially less sensitivity to ibrutinib-induced apoptosis. Conclusions This study identifies that CLL harboring del17p/TP53 mutated cells are substantially less sensitive to ibrutinib-induced apoptosis than del17p/TP53 wild type cells. PMID:27535981

Genetic analyses of isolated high-grade pancreatic intraepithelial neoplasia (HG-PanIN) reveal paucity of alterations in TP53 and SMAD4.

PubMed

Hosoda, Waki; Chianchiano, Peter; Griffin, James F; Pittman, Meredith E; Brosens, Lodewijk Aa; Noë, Michaël; Yu, Jun; Shindo, Koji; Suenaga, Masaya; Rezaee, Neda; Yonescu, Raluca; Ning, Yi; Albores-Saavedra, Jorge; Yoshizawa, Naohiko; Harada, Kenichi; Yoshizawa, Akihiko; Hanada, Keiji; Yonehara, Shuji; Shimizu, Michio; Uehara, Takeshi; Samra, Jaswinder S; Gill, Anthony J; Wolfgang, Christopher L; Goggins, Michael G; Hruban, Ralph H; Wood, Laura D

2017-05-01

High-grade pancreatic intraepithelial neoplasia (HG-PanIN) is the major precursor of pancreatic ductal adenocarcinoma (PDAC) and is an ideal target for early detection. To characterize pure HG-PanIN, we analysed 23 isolated HG-PanIN lesions occurring in the absence of PDAC. Whole-exome sequencing of five of these HG-PanIN lesions revealed a median of 33 somatic mutations per lesion, with a total of 318 mutated genes. Targeted next-generation sequencing of 17 HG-PanIN lesions identified KRAS mutations in 94% of the lesions. CDKN2A alterations occurred in six HG-PanIN lesions, and RNF43 alterations in five. Mutations in TP53, GNAS, ARID1A, PIK3CA, and TGFBR2 were limited to one or two HG-PanINs. No non-synonymous mutations in SMAD4 were detected. Immunohistochemistry for p53 and SMAD4 proteins in 18 HG-PanINs confirmed the paucity of alterations in these genes, with aberrant p53 labelling noted only in three lesions, two of which were found to be wild type in sequencing analyses. Sixteen adjacent LG-PanIN lesions from ten patients were also sequenced using targeted sequencing. LG-PanIN harboured KRAS mutations in 94% of the lesions; mutations in CDKN2A, TP53, and SMAD4 were not identified. These results suggest that inactivation of TP53 and SMAD4 are late genetic alterations, predominantly occurring in invasive PDAC. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Prevention of the neurocristopathy Treacher Collins syndrome through inhibition of p53 function.

PubMed

Jones, Natalie C; Lynn, Megan L; Gaudenz, Karin; Sakai, Daisuke; Aoto, Kazushi; Rey, Jean-Phillipe; Glynn, Earl F; Ellington, Lacey; Du, Chunying; Dixon, Jill; Dixon, Michael J; Trainor, Paul A

2008-02-01

Treacher Collins syndrome (TCS) is a congenital disorder of craniofacial development arising from mutations in TCOF1, which encodes the nucleolar phosphoprotein Treacle. Haploinsufficiency of Tcof1 perturbs mature ribosome biogenesis, resulting in stabilization of p53 and the cyclin G1-mediated cell-cycle arrest that underpins the specificity of neuroepithelial apoptosis and neural crest cell hypoplasia characteristic of TCS. Here we show that inhibition of p53 prevents cyclin G1-driven apoptotic elimination of neural crest cells while rescuing the craniofacial abnormalities associated with mutations in Tcof1 and extending life span. These improvements, however, occur independently of the effects on ribosome biogenesis; thus suggesting that it is p53-dependent neuroepithelial apoptosis that is the primary mechanism underlying the pathogenesis of TCS. Our work further implies that neuroepithelial and neural crest cells are particularly sensitive to cellular stress during embryogenesis and that suppression of p53 function provides an attractive avenue for possible clinical prevention of TCS craniofacial birth defects and possibly those of other neurocristopathies.

Identical mutations of the p53 tumor suppressor gene in the gliomatous and the sarcomatous components of gliosarcomas suggest a common origin from glial cells

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

Biernat, W.; Aguzzi, A.; Sure, U.

Gliosarcomas are morphologically heterogeneous tumors of the central nervous system composed of gliomatous and sarcomatous components. The histogenesis of the latter is still a matter of debate. As mutations of the p53 tumor suppressor gene represent an early event in the development of gliomas, we attempted to determine whether both components of gliosarcomas share identical alterations of the p53 gene. Using single-strand conformation analysis (SSCA) and direct DNA sequencing of the p53 gene, we analyzed dissected gliomatous and sarcomatous parts of 12 formalin-fixed, paraffin-embedded gliosarcomas. The two tumors that contained a p53 alteration were found to carry the identical mutationmore » (exon 5; codon 151, CCC {r_arrow} TCC; codon 173, GTG {r_arrow} GTA) in the gliomatous and the sarcomatous components. These findings suggest a common origin of the two cellular components from neoplastic glial cells. 37 refs., 3 figs., 1 tab.« less

Roles of the functional loss of p53 and other genes in astrocytoma tumorigenesis and progression.

PubMed Central

Nozaki, M.; Tada, M.; Kobayashi, H.; Zhang, C. L.; Sawamura, Y.; Abe, H.; Ishii, N.; Van Meir, E. G.

1999-01-01

Loss of function of the p53 tumor suppressor gene due to mutation occurs early in astrocytoma tumorigenesis in about 30-40% of cases. This is believed to confer a growth advantage to the cells, allowing them to clonally expand due to loss of the p53-controlled G1 checkpoint and apoptosis. Genetic instability due to the impaired ability of p53 to mediate DNA damage repair further facilitates the acquisition of new genetic abnormalities, leading to malignant progression of an astrocytoma into anaplastic astrocytoma. This is reflected by a high rate of p53 mutation (60-70%) in anaplastic astrocytomas. The cell cycle control gets further compromised in astrocytoma by alterations in one of the G1/S transition control genes, either loss of the p16/CDKN2 or RB genes or amplification of the cyclin D gene. The final progression process leading to glioblastoma multiforme seems to need additional genetic abnormalities in the long arm of chromosome 10; one of which is deletion and/or functional loss of the PTEN/MMAC1 gene. Glioblastomas also occur as primary (de novo) lesions in patients of older age, without p53 gene loss but with amplification of the epidermal growth factor receptor (EGFR) genes. In contrast to the secondary glioblastomas that evolve from astrocytoma cells with p53 mutations in younger patients, primary glioblastomas seem to be resistant to radiation therapy and thus show a poorer prognosis. The evaluation and design of therapeutic modalities aimed at preventing malignant progression of astrocytomas and glioblastomas should now be based on stratifying patients with astrocytic tumors according to their genetic diagnosis. PMID:11550308

The p53-Deficient Mouse as a Breast Cancer Model

DTIC Science & Technology

1995-10-01

M.A. Gryka , F.Z. Bischoff, M.A. Tain- Halachmi, R.T. Bronson, and R.A. Weinberg. 1994. Tumor sky, and S.H. Friend. 1990. Germ line p53 mutations in a...J. Kassel, M.A. Gryka , F.Z. Bischoff, Weaver-Feldhaus, W. Ding, Z. Gholami, P. Soderkvist, L. M.A. Tainsky, and S.H. Friend. 1990. Germ line p53

Keeping mammalian mutation load in check: regulation of the activity of error-prone DNA polymerases by p53 and p21.

PubMed

Livneh, Zvi

2006-09-01

To overcome DNA lesions that block replication the cell employs translesion DNA synthesis (TLS) polymerases, a group of low fidelity DNA polymerases that have the capacity to bypass a wide range of DNA lesions. This TLS process is also termed error-prone repair, due to its inherent mutagenic nature. We have recently shown that the tumor suppressor p53 and the cell cycle inhibitor p21 are global regulators of TLS. When these proteins are missing or nonfunctional, TLS gets out of control: its extent increases to very high levels, and its fidelity decreases, causing an overall increase in mutation load. This may be explained by the loss of selectivity in the bypass of specific DNA lesions by their cognate specialized polymerases, such that lesion bypass continues to a maximum, regardless of the price paid in increased mutations. The p53 and p21 proteins are also required for efficient UV light-induced monoubiquitination of PCNA, which is consistent with a model in which this modification of PCNA is necessary but not sufficient for the normal activity of TLS. This regulation suggests that TLS evolved in mammals as a system that balances gain in survival with a tolerable mutational cost, and that disturbing this balance causes a potentially harmful increase in mutations, which might play a role in carcinogenesis.

p53: traffic cop at the crossroads of DNA repair and recombination.

PubMed

Sengupta, Sagar; Harris, Curtis C

2005-01-01

p53 mutants that lack DNA-binding activities, and therefore, transcriptional activities, are among the most common mutations in human cancer. Recently, a new role for p53 has come to light, as the tumour suppressor also functions in DNA repair and recombination. In cooperation with its function in transcription, the transcription-independent roles of p53 contribute to the control and efficiency of DNA repair and recombination.

p53 regulates mesenchymal stem cell-mediated tumor suppression in a tumor microenvironment through immune modulation.

PubMed

Huang, Y; Yu, P; Li, W; Ren, G; Roberts, A I; Cao, W; Zhang, X; Su, J; Chen, X; Chen, Q; Shou, P; Xu, C; Du, L; Lin, L; Xie, N; Zhang, L; Wang, Y; Shi, Y

2014-07-17

p53 is one of the most studied genes in cancer biology, and mutations in this gene may be predictive for the development of many types of cancer in humans and in animals. However, whether p53 mutations in non-tumor stromal cells can affect tumor development has received very little attention. In this study, we show that B16F0 melanoma cells form much larger tumors in p53-deficient mice than in wild-type mice, indicating a potential role of p53 deficiency in non-tumor cells of the microenvironment. As mesenchymal stem cells (MSCs) are attracted to tumors and form a major component of the tumor microenvironment, we examined the potential role of p53 status in MSCs in tumor development. We found that larger tumors resulted when B16F0 melanoma cells were co-injected with bone marrow MSCs derived from p53-deficient mice rather than MSCs from wild-type mice. Interestingly, this tumor-promoting effect by p53-deficient MSCs was not observed in non-obese diabetic/severe combined immunodeficiency mice, indicating the immune response has a critical role. Indeed, in the presence of inflammatory cytokines, p53-deficient MSCs expressed more inducible nitric oxide synthase (iNOS) and exhibited greater immunosuppressive capacity. Importantly, tumor promotion by p53-deficient MSCs was abolished by administration of S-methylisothiourea, an iNOS inhibitor. Therefore, our data demonstrate that p53 status in tumor stromal cells has a key role in tumor development by modulating immune responses.

Novel mutations and their genotype-phenotype correlations in patients with Noonan syndrome, using next-generation sequencing.

PubMed

Tafazoli, Alireza; Eshraghi, Peyman; Pantaleoni, Francesca; Vakili, Rahim; Moghaddassian, Morteza; Ghahraman, Martha; Muto, Valentina; Paolacci, Stefano; Golyan, Fatemeh Fardi; Abbaszadegan, Mohammad Reza

2018-03-01

Noonan Syndrome (NS) is an autosomal dominant disorder with many variable and heterogeneous conditions. The genetic basis for 20-30% of cases is still unknown. This study evaluates Iranian Noonan patients both clinically and genetically for the first time. Mutational analysis of PTPN11 gene was performed in 15 Iranian patients, using PCR and Sanger sequencing at phase one. Then, as phase two, Next Generation Sequencing (NGS) in the form of targeted resequencing was utilized for analysis of exons from other related genes. Homology modelling for the novel founded mutations was performed as well. The genotype, phenotype correlation was done according to the molecular findings and clinical features. Previously reported mutation (p.N308D) in some patients and a novel mutation (p.D155N) in one of the patients were identified in phase one. After applying NGS methods, known and new variants were found in four patients in other genes, including: CBL (p. V904I), KRAS (p. L53W), SOS1 (p. I1302V), and SOS1 (p. R552G). Structural studies of two deduced novel mutations in related genes revealed deficiencies in the mutated proteins. Following genotype, phenotype correlation, a new pattern of the presence of intellectual disability in two patients was registered. NS shows strong variable expressivity along the high genetic heterogeneity especially in distinct populations and ethnic groups. Also possibly unknown other causative genes may be exist. Obviously, more comprehensive and new technologies like NGS methods are the best choice for detection of molecular defects in patients for genotype, phenotype correlation and disease management. Copyright © 2017 Medical University of Bialystok. Published by Elsevier B.V. All rights reserved.

Similar DNA methylation pattern in lung tumours from smokers and never-smokers with second-hand tobacco smoke exposure.

PubMed

Scesnaite, Asta; Jarmalaite, Sonata; Mutanen, Pertti; Anttila, Sisko; Nyberg, Fredrik; Benhamou, Simone; Boffetta, Paolo; Husgafvel-Pursiainen, Kirsti

2012-07-01

Tobacco smoke causes lung cancer in smokers and in never-smokers exposed to second-hand tobacco smoke (SHS). Nonetheless, molecular mechanisms of lung cancer in SHS-exposed never-smokers are still elusive. We studied lung cancers from current smokers (n = 109), former smokers (n = 56) and never-smokers (n = 47) for promoter hypermethylation of five tumour suppressor genes--p16, RARB, RASSF1, MGMT and DAPK1--using methylation-specific polymerase chain reaction. Lung tumours from ever-smokers suggested an increased risk of p16 hypermethylation as compared to never-smokers (P = 0.073), with former smokers having the highest frequency of p16 hypermethylation (P = 0.044 versus current smokers and P = 0.009 versus never-smokers). In the never-smoking group, p16 hypermethylation was seen in lung tumours from SHS-exposed individuals (4/33; 12%) but in none of the non-exposed individuals (0/9). The overall occurrence of hypermethylation (measured both as methylation index and as number of genes affected) was similar in those ever exposed to tobacco smoke (smokers, SHS-exposed never-smokers) and differed from non-exposed never-smokers. In multivariate analysis, p16 hypermethylation was more prevalent in lung tumours from male than female patients (P = 0.018) and in squamous cell carcinomas than in adenocarcinomas (P = 0.025). Occurrence of TP53 mutation in the tumour was associated with hypermethylation of at least one gene (P = 0.027). In all, our data suggest that promoter hypermethylation pattern in SHS-exposed never-smokers resembles that observed in smokers. Association between TP53 mutation, a hallmark of smokers' lung cancer, and methylation of one or more of the lung cancer-related genes studied, provides further evidence for common tobacco smoke-related origin for both types of molecular alterations.

Structure-Based Design of Molecules to Reactivate Tumor-Derived p53 Mutations

DTIC Science & Technology

2007-06-01

cluster in conserved regions or “hot spots” (Hainaut and Hollstein, 2000). Missense mutations leading to amino acid changes are the most common p53...domain stabilization compounds. Analysis of the residue-specific temperature factors of the high resolution core domain structure, coupled with a...second scoring results, 13 compounds (10 from the SPECS database and 3 from the TimTec database) were selected for further analysis using solution

Mutant p53 proteins counteract autophagic mechanism sensitizing cancer cells to mTOR inhibition.

PubMed

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

2016-08-01

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

Changes in O-Linked N-Acetylglucosamine (O-GlcNAc) Homeostasis Activate the p53 Pathway in Ovarian Cancer Cells*

PubMed Central

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

2016-01-01

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

Immunohistochemical analysis of P53 protein in odontogenic cysts

PubMed Central

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

2010-01-01

The p53 is a well-known tumor suppressor gene, the mutations of which are closely related to the decreased differentiation of cells. Findings of studies on immunohistochemical P53 expression in odontogenic cysts are controversial. The present study was carried-out to investigate the immunohistochemical expression of P53 protein in odontogenic cysts. Thirty paraffin blocks of diagnosed odontogenic cysts were processed to determine the immunohistochemical expression of P53 protein. Nine of the 11 odontogenic keratocysts (81.8%) expressed P53, one of three dentigerous cyst cases expressed P53, while none of the 16 radicular cysts expressed P53 protein. The findings of the present work supported the reclassification of OKC as keratocystic odontogenic tumor. PMID:23960493

Co-operative intra-protein structural response due to protein-protein complexation revealed through thermodynamic quantification: study of MDM2-p53 binding

NASA Astrophysics Data System (ADS)

Samanta, Sudipta; Mukherjee, Sanchita

2017-10-01

The p53 protein activation protects the organism from propagation of cells with damaged DNA having oncogenic mutations. In normal cells, activity of p53 is controlled by interaction with MDM2. The well understood p53-MDM2 interaction facilitates design of ligands that could potentially disrupt or prevent the complexation owing to its emergence as an important objective for cancer therapy. However, thermodynamic quantification of the p53-peptide induced structural changes of the MDM2-protein remains an area to be explored. This study attempts to understand the conformational free energy and entropy costs due to this complex formation from the histograms of dihedral angles generated from molecular dynamics simulations. Residue-specific quantification illustrates that, hydrophobic residues of the protein contribute maximum to the conformational thermodynamic changes. Thermodynamic quantification of structural changes of the protein unfold the fact that, p53 binding provides a source of inter-element cooperativity among the protein secondary structural elements, where the highest affected structural elements (α2 and α4) found at the binding site of the protein affects faraway structural elements (β1 and Loop1) of the protein. The communication perhaps involves water mediated hydrogen bonded network formation. Further, we infer that in inhibitory F19A mutation of P53, though Phe19 is important in the recognition process, it has less prominent contribution in the stability of the complex. Collectively, this study provides vivid microscopic understanding of the interaction within the protein complex along with exploring mutation sites, which will contribute further to engineer the protein function and binding affinity.

Tumor markers and rectal cancer: support for an inflammation-related pathway

PubMed Central

Slattery, Martha L.; Wolff, Roger K.; Herrick, Jennifer; Caan, Bette J.; Samowitz, Wade

2009-01-01

Inflammation may be a key element in the etiology of colorectal cancer (CRC). In this study we examine associations between factors related to inflammation and specific rectal cancer mutations. A population-based study of 750 rectal cancer cases with interview and tumor DNA were compared to 1205 population-based controls. Study participants were from Utah and the Northern California Kaiser Permanente Medical Care Program. Tumor DNA was analyzed for TP53 and KRAS2 mutations and CpG Island methylator phenotype (CIMP). We assessed how these tumor markers were associated with use of anti-inflammatory drugs, polymorphisms in the IL6 genes (rs1800795 and rs1800796), and dietary antioxidants. Ibuprofen-type drugs, IL6 polymorphisms (rs1800796), and dietary alpha tocopherol and lycopene significantly altered likelihood of having a TP53 mutation. This was especially true for TP53 transversion mutations and dietary antioxidants (OR for beta carotene 0.51 95% CI 0.27,0.97, p trend 0.03; alpha tocopherol 0.41 95% CI 0.20,0.84, p trend 0.02) Beta carotene and ibuprofen significantly altered risk of KRAS2 tumors. The associations between lutein and tocopherol and TP53 and KRAS2 mutations were modified by IL6 genotype. These results suggest that inflammation-related factors may have unique associations with various rectal tumor markers. Many factors involved in an inflammation related pathway were associated with TP53 mutations and some dietary factors appeared to be modified by IL6 genotype. PMID:19452524

A stapled p53 helix overcomes HDMX-mediated suppression of p53.

PubMed

Bernal, Federico; Wade, Mark; Godes, Marina; Davis, Tina N; Whitehead, David G; Kung, Andrew L; Wahl, Geoffrey M; Walensky, Loren D

2010-11-16

Cancer cells neutralize p53 by deletion, mutation, proteasomal degradation, or sequestration to achieve a pathologic survival advantage. Targeting the E3 ubiquitin ligase HDM2 can lead to a therapeutic surge in p53 levels. However, the efficacy of HDM2 inhibition can be compromised by overexpression of HDMX, an HDM2 homolog that binds and sequesters p53. Here, we report that a stapled p53 helix preferentially targets HDMX, blocks the formation of inhibitory p53-HDMX complexes, induces p53-dependent transcriptional upregulation, and thereby overcomes HDMX-mediated cancer resistance in vitro and in vivo. Importantly, our analysis of p53 interaction dynamics provides a blueprint for reactivating the p53 pathway in cancer by matching HDM2, HDMX, or dual inhibitors to the appropriate cellular context. Copyright © 2010 Elsevier Inc. All rights reserved.

Mutational load distribution analysis (MLDA) in pancreatic cancer — EDRN Public Portal

Cancer.gov

Certain p16 mutation carriers showed mutation elevations in the specific Ki-ras and p53 alleles significantly higher than normal, similar to controls with pancreatitis. Two individuals from separate families started out with "low risk" readings subsequently converted to "high risk" categorization and remained there in each sequential exam.

Molecular heterogeneity assessment by next-generation sequencing and response to gefitinib of EGFR mutant advanced lung adenocarcinoma

PubMed Central

Amato, Eliana; Fassan, Matteo; Novello, Silvia; Peretti, Umberto; Vavalà, Tiziana; Kinspergher, Stefania; Righi, Luisella; Santo, Antonio; Brunelli, Matteo; Corbo, Vincenzo; Giglioli, Eliana; Sperduti, Isabella; Milella, Michele; Chilosi, Marco; Scarpa, Aldo; Tortora, Giampaolo

2015-01-01

Cancer molecular heterogeneity might explain the variable response of EGFR mutant lung adenocarcinomas to tyrosine kinase inhibitors (TKIs). We assessed the mutational status of 22 cancer genes by next-generation sequencing (NGS) in poor, intermediate or good responders to first-line gefitinib. Clinical outcome was correlated with Additional Coexisting Mutations (ACMs) and the EGFR Proportion of Mutated Alleles (PMA). Thirteen ACMs were found in 10/17 patients: TP53 (n=6), KRAS (n=2), CTNNB1 (n=2), PIK3CA, SMAD4 and MET (n=1 each). TP53 mutations were exclusive of poor/intermediate responders (66.7% versus 0, p=0.009). Presence of ACMs significantly affected both PFS (median 3.0 versus 12.3 months, p=0.03) and survival (3.6 months versus not reached, p=0.03). TP53 mutation was the strongest negative modifier (median PFS 4.0 versus 14.0 months). Higher EGFR PMA was present in good versus poor/intermediate responders. Median PFS and survival were longer in patients with EGFR PMA ≥0.36 (12.0 versus 4.0 months, p=0.31; not reached versus 18.0 months, p=0.59). Patients with an EGFR PMA ≥0.36 and no ACMs fared significantly better (p=0.03), with a trend towards increased survival (p=0.06). Our exploratory data suggest that a quantitative (PMA) and qualitative (ACMs) molecular heterogeneity assessment using NGS might be useful for a better selection of patients. PMID:25904052

Immunohistochemical detection of p53 protein in ameloblastoma types.

PubMed

el-Sissy, N A

1999-05-01

Overexpression of p53 protein in unicystic ameloblastoma (uAB) is denser than in the conventional ameloblastoma (cAB) type, indicating increased wild type p53--suppressing the growth potential of uAB and denoting the early event of neoplastic transformation, probably of a previous odontogenic cyst. Overexpression of p53 in borderline cAB and malignant ameloblastoma (mAB) types might reflect a mutational p53 protein playing an oncogenic role, promoting tumour growth. Overexpression of p53 protein could be a valid screening method for predicting underlying malignant genetic changes in AB types, through increased frequency of immunoreactive cells or increased staining density.

CRISPR-mediated direct mutation of cancer genes in the mouse liver

PubMed Central

Xue, Wen; Chen, Sidi; Yin, Hao; Tammela, Tuomas; Papagiannakopoulos, Thales; Joshi, Nikhil S.; Cai, Wenxin; Yang, Gillian; Bronson, Roderick; Crowley, Denise G.; Zhang, Feng; Anderson, Daniel G.; Sharp, Phillip A.; Jacks, Tyler

2014-01-01

The study of cancer genes in mouse models has traditionally relied on genetically-engineered strains made via transgenesis or gene targeting in embryonic stem (ES) cells1. Here we describe a new method of cancer model generation using the CRISPR/Cas system in vivo in wild-type mice. We have used hydrodynamic injection to deliver a CRISPR plasmid DNA expressing Cas9 and single guide RNAs (sgRNAs)2–4 to the liver and directly target the tumor suppressor genes Pten5 and p536, alone and in combination. CRISPR-mediated Pten mutation led to elevated Akt phosphorylation and lipid accumulation in hepatocytes, phenocopying the effects of deletion of the gene using Cre-LoxP technology7, 8. Simultaneous targeting of Pten and p53 induced liver tumors that mimicked those caused by Cre-loxP-mediated deletion of Pten and p53. DNA sequencing of liver and tumor tissue revealed insertion or deletion (indel) mutations of the tumor suppressor genes, including bi-allelic mutations of both Pten and p53 in tumors. Furthermore, co-injection of Cas9 plasmids harboring sgRNAs targeting the β-Catenin gene (Ctnnb1) and a single-stranded DNA (ssDNA) oligonucleotide donor carrying activating point mutations led to the generation of hepatocytes with nuclear localization of β-Catenin. This study demonstrates the feasibility of direct mutation of tumor suppressor genes and oncogenes in the liver using the CRISPR/Cas system, which presents a new avenue for rapid development of liver cancer models and functional genomics. PMID:25119044

Li-Fraumeni syndrome: cancer risk assessment and clinical management.

PubMed

McBride, Kate A; Ballinger, Mandy L; Killick, Emma; Kirk, Judy; Tattersall, Martin H N; Eeles, Rosalind A; Thomas, David M; Mitchell, Gillian

2014-05-01

Carriers of germline mutations in the TP53 gene, encoding the cell-cycle regulator and tumour suppressor p53, have a markedly increased risk of cancer-related morbidity and mortality during both childhood and adulthood, and thus require appropriate and effective cancer risk management. However, the predisposition of such patients to multiorgan tumorigenesis presents a specific challenge for cancer risk management programmes. Herein, we review the clinical implications of germline mutations in TP53 and the evidence for cancer screening and prevention strategies in individuals carrying such mutations, as well as examining the potential psychosocial implications of lifelong management for a ubiquitous cancer risk. In addition, we propose an evidence-based framework for the clinical management of TP53 mutation carriers and provide a platform for addressing the management of other cancer predisposition syndromes that can affect multiple organs.

Direct observations of conformational distributions of intrinsically disordered p53 peptides using UV Raman and explicit solvent simulations

PubMed Central

Xiong, Kan; Zwier, Matthew C.; Myshakina, Nataliya S.; Burger, Virginia M.; Asher, Sanford A.; Chong, Lillian T.

2011-01-01

We report the first experimental measurements of Ramachandran Ψ-angle distributions for intrinsically disordered peptides: the N-terminal peptide fragment of tumor suppressor p53 and its P27 mutant form. To provide atomically detailed views of the conformational distributions, we performed classical, explicit-solvent molecular dynamics simulations on the microsecond timescale. Upon binding its partner protein, MDM2, wild-type p53 peptide adopts an α-helical conformation. Mutation of Pro27 to serine results in the highest affinity yet observed for MDM2-binding of the p53 peptide. Both UV resonance Raman spectroscopy (UVRR) and simulations reveal that the P27S mutation decreases the extent of PPII helical content and increases the probability for conformations that are similar to the α-helical MDM2-bound conformation. In addition, UVRR measurements were performed on peptides that were isotopically labeled at the Leu26 residue preceding the Pro27 in order to determine the conformational distributions of Leu26 in the wild-type and mutant peptides. The UVRR and simulation results are in quantitative agreement in terms of the change in the population of non-PPII conformations involving Leu26 upon mutation of Pro27 to serine. Finally, our simulations reveal that the MDM2-bound conformation of the peptide is significantly populated in both the wild-type and mutant isolated peptide ensembles in their unbound states, suggesting that MDM2 binding of the p53 peptides may involve conformational selection. PMID:21528875

Papillomavirus, p53 alteration, and primary carcinoma of the vulva.

PubMed

Pilotti, S; D'Amato, L; Della Torre, G; Donghi, R; Longoni, A; Giarola, M; Sampietro, G; De Palo, G; Pierotti, M A; Rilke, F

1995-12-01

Twenty-nine samples from 28 cases of vulvar squamous cell carcinoma, of which 13 fulfilled the criteria of the bowenoid subtype (mean age 45 years, range 31-68) and 16 of the usual subtype of invasive squamous cell carcinoma (ISCC) (mean age 67.5 years, range 34-83) were investigated for human papillomavirus (HPV) DNA, TP53 alterations, and mdm2 and bcl-2 gene product deregulation. Microscopically all the bowenoid subtype cases (group I) showed a high-grade intraepithelial (VIN 3, carcinoma in situ) lesion associated with early invasive carcinoma in six cases and overt invasive carcinoma in one. By contrast, no evidence of early carcinoma was present in the ISCCs (group II). By in situ hybridization and/or Southern blot hybridization or polymerase chain reaction (PCR), HPV DNA was detected in all cases of group I and in four of 16 cases (25%) of group II, two only by Southern blot after PCR. By single-strand conformation polymorphism and immunocytochemistry only wild-type TP53 and absence of detectable p53 product, respectively, were found in all cases of group I, i.e., in high-risk HPV-positive carcinomas, whereas mutations and/or p53 overexpression accounted for 75% in group II, i.e., in mainly HPV-negative carcinomas. The TP53 gene mutations observed in invasive carcinomas were significantly related to node-positive cases (p = 0.04). Taken together and in agreement with in vitro data, these results support the view that an alteration of TP53, gained either by interaction with viral oncoproteins or by somatic mutations, is a crucial event in the pathogenesis of vulvar carcinomas, but that TP53 mutations are mainly associated with disease progression. Finally, a preliminary immunocytochemical analysis seems to speak against the possible involvement of both MDM2 and BCL-2 gene products in the development of vulvar carcinoma.

Alterations of p53 in tumorigenic human bronchial epithelial cells correlate with metastatic potential

NASA Technical Reports Server (NTRS)

Piao, C. Q.; Willey, J. C.; Hei, T. K.; Hall, E. J. (Principal Investigator)

1999-01-01

The cellular and molecular mechanisms of radiation-induced lung cancer are not known. In the present study, alterations of p53 in tumorigenic human papillomavirus-immortalized human bronchial epithelial (BEP2D) cells induced by a single low dose of either alpha-particles or 1 GeV/nucleon (56)Fe were analyzed by PCR-single-stranded conformation polymorphism (SSCP) coupled with sequencing analysis and immunoprecipitation assay. A total of nine primary and four secondary tumor cell lines, three of which were metastatic, together with the parental BEP2D and primary human bronchial epithelial (NHBE) cells were studied. The immunoprecipitation assay showed overexpression of mutant p53 proteins in all the tumor lines but not in NHBE and BEP2D cells. PCR-SSCP and sequencing analysis found band shifts and gene mutations in all four of the secondary tumors. A G-->T transversion in codon 139 in exon 5 that replaced Lys with Asn was detected in two tumor lines. One mutation each, involving a G-->T transversion in codon 215 in exon 6 (Ser-->lle) and a G-->A transition in codon 373 in exon 8 (Arg-->His), was identified in the remaining two secondary tumors. These results suggest that p53 alterations correlate with tumorigenesis in the BEP2D cell model and that mutations in the p53 gene may be indicative of metastatic potential.

Mutational analysis of AGXT gene in Libyan children with primary hyperoxaluria type 1 at Tripoli Children Hospital.

PubMed

Rhuma, Naziha R; Fituri, Omar A; Sabei, Laila T

2018-01-01

Primary hyperoxaluria type 1 (PH1) is an inborn error of glyoxylate metabolism. It results from genetic mutation of the AGXT gene. The study objective was to verify the clinical and epidemiological patterns of PH1 in Libyan children at Tripoli Children Hospital confirmed by AGXT gene mutation. A descriptive case series study of 53 children with PH1 diagnosed between 1994 and 2015 was carried out in the Nephrology Unit at Tripoli Children Hospital. Diagnosis of PH1 was based on the clinical presentation (renal stones or nephrocalcinosis), positive family history of PH1, and high 24 h urinary oxalate. Sampling for AGXT gene mutation was collected from April 2012 to December. 2015. Among the 53 children included, males composed of 62.3% of patients. Their age at presentation ranged between two months and 20 years with a mean age of 55.4 ± 48 months. The parents of 81.1% of these patients had positive consanguinity. Forty (75.5%) patients were from South West (mountain area), and 16 (40%) of them were from Yefrin. The most common mutation found in this study was c.731T>C (p.lle244thr) seen in 32 (71%) of children, and interestingly, among these patients, 87.1% were homozygous in gene typing, 86.2% had positive history of consanguinity, 71.4% were from South West (mountain area), 96.6% had family history of PH1, and 20% presented with impaired renal function. The patients with this mutation were younger at presentation than that with other genes, and it was more prevalent among boys (61.3%). Thus, the most common gene mutation found in Libyan children with PH1 was c.731T>C (p.lle244thr) and this is more likely due to the strong genetic pooling caused by the high consanguinity rate which requires an extensive genetic counseling.

Using an international p53 mutation database as a foundation for an online laboratory in an upper level undergraduate biology class.

PubMed

Melloy, Patricia G

2015-01-01

A two-part laboratory exercise was developed to enhance classroom instruction on the significance of p53 mutations in cancer development. Students were asked to mine key information from an international database of p53 genetic changes related to cancer, the IARC TP53 database. Using this database, students designed several data mining activities to look at the changes in the p53 gene from a number of perspectives, including potential cancer-causing agents leading to particular changes and the prevalence of certain p53 variations in certain cancers. In addition, students gained a global perspective on cancer prevalence in different parts of the world. Students learned how to use the database in the first part of the exercise, and then used that knowledge to search particular cancers and cancer-causing agents of their choosing in the second part of the exercise. Students also connected the information gathered from the p53 exercise to a previous laboratory exercise looking at risk factors for cancer development. The goal of the experience was to increase student knowledge of the link between p53 genetic variation and cancer. Students also were able to walk a similar path through the website as a cancer researcher using the database to enhance bench work-based experiments with complementary large-scale database p53 variation information. © 2014 The International Union of Biochemistry and Molecular Biology.

P53 Suppression of Homologous Recombination and Tumorigenesis

DTIC Science & Technology

2011-01-01

huge strides have been made in the numbers of mice breed and relevant cells collected for the purposes of experiments outlined in the aims below. The PI... breeding colony of R172P, R172H, Wild type and p53 null mice in order to have sufficient numbers of animals to perform the in vivo pun assay. Mouse...Strains and Breeding Cohorts Mice heterozygous for the point mutations p53R172P and p53R172H both on a C57BL/6 genetic background were kindly

Specific UV-induced mutation spectrum in the p53 gene of skin tumors from DNA-repair-deficient xeroderma pigmentosum patients

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

Dumaz, N.; Drougard, C.; Sarasin, A.

1993-11-15

The UV component of sunlight is the major carcinogen involved in the etiology of skin cancers. The authors have studied the rare, hereditary syndrome xeroderma pigmentosum (XP), which is characterized by a very high incidence of cutaneous tumors on exposed skin at an early age, probably due to a deficiency in excision repair of UV-induced lesions. It is interesting to determine the UV mutation spectrum in XP skin tumors in order to correlate the absence of repair of specific DNA lesions and the initiation of skin tumors. The p53 gene is frequently mutated in human cancers and represents a goodmore » target for studying mutation spectra since there are >100 potential sites for phenotypic mutations. Using reverse transcription-PCR and single-strand conformation polymorphism to analyze >40 XP skin tumors (mainly basal and squamous cell carcinomas), the authors have found that 40% (17 out of 43) contained at least one point mutation on the p53 gene. All the mutations were located at dipyrimidine sites, essentially at CC sequences, which are hot spots for UV-induced DNA lesions. Sixty-one percent of these mutations were tandem CC [yields] TT mutations considered to be unique to UV-induced lesions; these mutations are not observed in internal human tumors. All the mutations, except two, must be due to translesion synthesis of unrepaired dipyrimidine lesions left on the nontranscribed strand. These results show the existence of preferential repair of UV lesions [either pyrimidine dimers or pyrimidine-pyrimidone (6-4) photoproducts] on the transcribed strand in human tissues.« less

Hepatitis B and Hepatitis C Infection Biomarkers and TP53 Mutations in Hepatocellular Carcinomas from Colombia

PubMed Central

Navas, Maria-Cristina; Suarez, Iris; Carreño, Andrea; Uribe, Diego; Rios, Wilson Alfredo; Cortes-Mancera, Fabian; Martel, Ghyslaine; Vieco, Beatriz; Lozano, Diana; Jimenez, Carlos; Gouas, Doriane; Osorio, German; Hoyos, Sergio; Restrepo, Juan Carlos; Correa, Gonzalo; Jaramillo, Sergio; Lopez, Rocio; Bravo, Luis Eduardo; Arbelaez, Maria Patricia; Scoazec, Jean-Yves; Abedi-Ardekani, Behnoush; Santella, Regina M.; Chemin, Isabelle; Hainaut, Pierre

2011-01-01

Hepatocellular Carcinoma (HCC) is a leading cause of cancer-related death worldwide. Globally, the most important HCC risk factors are Hepatitis B Virus (HBV) and/or Hepatitis C Virus (HCV), chronic alcoholism, and dietary exposure to aflatoxins. We have described the epidemiological pattern of 202 HCC samples obtained from Colombian patients. Additionally we investigated HBV/HCV infections and TP53 mutations in 49 of these HCC cases. HBV biomarkers were detected in 58.1% of the cases; HBV genotypes F and D were characterized in three of the samples. The HCV biomarker was detected in 37% of the samples while HBV/HCV coinfection was found in 19.2%. Among TP53 mutations, 10.5% occur at the common aflatoxin mutation hotspot, codon 249. No data regarding chronic alcoholism was available from the cases. In conclusion, in this first study of HCC and biomarkers in a Colombian population, the main HCC risk factor was HBV infection. PMID:22114738

High frequency of TP53 but not K-ras gene mutations in Bolivian patients with gallbladder cancer.

PubMed

Asai, Takao; Loza, Ernesto; Roig, Guido Villa-Gomez; Ajioka, Yoichi; Tsuchiya, Yasuo; Yamamoto, Masaharu; Nakamura, Kazutoshi

2014-01-01

Although genetic characteristics are considered to be a factor influencing the geographic variation in the prevalence of gallbladder cancer (GBC), they have not been well studied in Bolivia, which has a high prevalence rate of GBC. The purpose of this study was to examine the frequency of TP53 and K-ras mutations in Bolivian patients with GBC and to compare them with our previous data obtained in other high-GBC-prevalence countries, namely Japan, Chile, and Hungary. DNA was extracted from cancer sites in paraffin-embedded tissue from 36 patients using a microdissection technique. TP53 mutations at exons 5 to 8 and K-ras mutations at codons 12, 13 and 61 were examined using direct sequencing techniques. The data obtained were compared with those in the other high-GBC-prevalence countries. Of the 36 patients, 18 (50.0%) had a TP53 mutation (one mutation in each of 17 patients and three mutations in one patient), and only one (2.8%) had a K-ras mutation. Of the 20 TP53 mutations, 12 were of the transition type (60.0%). This rate was significantly lower than that in Chile (12/12, P<0.05). In addition, three mutations were of the CpG transition type (15.0%), which is a feature of endogenous mutation. All three were found in the hot spot region of the TP53 gene. In contrast, G:C to T:A transversion was found in Bolivia, suggesting the presence of exogenous carcinogens. Our findings suggest that the development of GBC in Bolivia is associated with both exogenous carcinogens and endogenous mechanisms. The identification of an environmental risk factor for GBC is needed to confirm these findings.

Characterization of a gene product (Sec53p) required for protein assembly in the yeast endoplasmic reticulum

PubMed Central

1985-01-01

SEC53, a gene that is required for completion of assembly of proteins in the endoplasmic reticulum in yeast, has been cloned, sequenced, and the product localized by cell fractionation. Complementation of a sec53 mutation is achieved with unique plasmids from genomic or cDNA expression banks. These inserts contain the authentic gene, a cloned copy of which integrates at the sec53 locus. An open reading frame in the insert predicts a 29-kD protein with no significant hydrophobic character. This prediction is confirmed by detection of a 28-kD protein overproduced in cells that carry SEC53 on a multicopy plasmid. To follow Sec53p more directly, a LacZ-SEC53 gene fusion has been constructed which allows the isolation of a hybrid protein for use in production of antibody. With such an antibody, quantitative immune decoration has shown that the sec53-6 mutation decreases the level of Sec53p at 37 degrees C, while levels comparable to wild-type are seen at 24 degrees C. An eightfold overproduction of Sec53p accompanies transformation of cells with a multicopy plasmid containing SEC53. Cell fractionation, performed with conditions that preserve the lumenal content of the endoplasmic reticulum (ER), shows Sec53p highly enriched in the cytosol fraction. We suggest that Sec53p acts indirectly to facilitate assembly in the ER, possibly by interacting with a stable ER component, or by providing a small molecule, other than an oligosaccharide precursor, necessary for the assembly event. PMID:3905826

Detection of HPV-DNA, p53 alterations, and methylation in penile squamous cell carcinoma in Japanese men.

PubMed

Yanagawa, Naoki; Osakabe, Mitsumasa; Hayashi, Masahiro; Tamura, Gen; Motoyama, Teiichi

2008-08-01

Penile carcinoma is a rare disease, accordingly there are few studies on molecular changes, and these results also vary greatly. A total of 26 penile squamous cell carcinomas in Japanese men were studied with respect to HPV, p53 alterations, and methylation of gene promoter region. HPV-DNA was detected in three of 26 patients (11.5%). Overexpression of p53 was observed in 13 of 26 patients (50%), and p53 gene mutations were detected in four of 26 patients (15.4%). The frequency of methylation was as follows: DAPK, 26.9% (7/26); FHIT, 88.4% (23/26); MGMT, 19.2% (5/26); p14, 3.8% (1/26); p16, 23.1% (6/26); RAR-beta, 23.1% (6/26); RASSF1A, 11.5% (3/26); and RUNX3, 42.3% (11/26). As for correlation between HPV and p53 alterations, and methylation status, mutations of the p53 gene were detected only in HPV-negative patients, and methylation was more frequently found in HPV-negative than in HPV-positive patients. The present results suggest that the majority of penile squamous cell carcinomas in Japanese men are unrelated to HPV, and gene alterations accumulate more frequently in HPV-unrelated penile carcinomas.

TP53, PIK3CA, FBXW7 and KRAS Mutations in Esophageal Cancer Identified by Targeted Sequencing.

PubMed

Zheng, Huili; Wang, Yan; Tang, Chuanning; Jones, Lindsey; Ye, Hua; Zhang, Guangchun; Cao, Weihai; Li, Jingwen; Liu, Lifeng; Liu, Zhencong; Zhang, Chao; Lou, Feng; Liu, Zhiyuan; Li, Yangyang; Shi, Zhenfen; Zhang, Jingbo; Zhang, Dandan; Sun, Hong; Dong, Haichao; Dong, Zhishou; Guo, Baishuai; Yan, H E; Lu, Qingyu; Huang, Xue; Chen, Si-Yi

2016-01-01

Esophageal cancer (EC) is a common malignancy with significant morbidity and mortality. As individual cancers exhibit unique mutation patterns, identifying and characterizing gene mutations in EC that may serve as biomarkers might help predict patient outcome and guide treatment. Traditionally, personalized cancer DNA sequencing was impractical and expensive. Recent technological advancements have made targeted DNA sequencing more cost- and time-effective with reliable results. This technology may be useful for clinicians to direct patient treatment. The Ion PGM and AmpliSeq Cancer Panel was used to identify mutations at 737 hotspot loci of 45 cancer-related genes in 64 EC samples from Chinese patients. Frequent mutations were found in TP53 and less frequent mutations in PIK3CA, FBXW7 and KRAS. These results demonstrate that targeted sequencing can reliably identify mutations in individual tumors that make this technology a possibility for clinical use. Copyright© 2016, International Institute of Anticancer Research (Dr. John G. Delinasios), All rights reserved.

VPS53 mutations cause progressive cerebello-cerebral atrophy type 2 (PCCA2).

PubMed

Feinstein, Miora; Flusser, Hagit; Lerman-Sagie, Tally; Ben-Zeev, Bruria; Lev, Dorit; Agamy, Orly; Cohen, Idan; Kadir, Rotem; Sivan, Sara; Leshinsky-Silver, Esther; Markus, Barak; Birk, Ohad S

2014-05-01

Progressive cerebello-cerebral atrophy (PCCA) leading to profound mental retardation, progressive microcephaly, spasticity and early onset epilepsy, was diagnosed in four non-consanguineous apparently unrelated families of Jewish Moroccan ancestry. Common founder mutation(s) were assumed. Genome-wide linkage analysis and whole exome sequencing were done, followed by realtime PCR and immunofluorescent microscopy. Genome-wide linkage analysis mapped the disease-associated gene to 0.5 Mb on chromosome 17p13.3. Whole exome sequencing identified only two mutations within this locus, which were common to the affected individuals: compound heterozygous mutations in VPS53, segregating as expected for autosomal recessive heredity within all four families, and common in Moroccan Jews (∼1:37 carrier rate). The Golgi-associated retrograde protein (GARP) complex is involved in the retrograde pathway recycling endocytic vesicles to Golgi; c.2084A>G and c.1556+5G>A VPS53 founder mutations are predicted to affect the C-terminal domain of VPS53, known to be critical to its role as part of this complex. Immunofluorescent microscopy demonstrated swollen and abnormally numerous CD63 positive vesicular bodies, likely intermediate recycling/late endosomes, in fibroblasts of affected individuals. Autosomal recessive PCCA type 2 is caused by VPS53 mutations.

Abrogation of p53 by its antisense in MCF-7 breast carcinoma cells increases cyclin D1 via activation of Akt and promotion of cell proliferation

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

Chhipa, Rishi Raj; Kumari, Ratna; Upadhyay, Ankur Kumar

2007-11-15

The p53 protein has been a subject of intense research interest since its discovery as about 50% of human cancers carry p53 mutations. Mutations in the p53 gene are the most frequent genetic lesions in breast cancers suggesting a critical role of p53 in breast cancer development, growth and chemosensitivity. This report describes the derivation and characterization of MCF-7As53, an isogenic cell line derived from MCF-7 breast carcinoma cells in which p53 was abrogated by antisense p53 cDNA. Similar to MCF-7 and simultaneously selected hygromycin resistant MCF-7H cells, MCF-7As53 cells have consistent basal epithelial phenotype, morphology, and estrogen receptor expressionmore » levels at normal growth conditions. Present work documents investigation of molecular variations, growth kinetics, and cell cycle related studies in relation to absence of wild-type p53 protein and its transactivation potential as well. Even though wild-type tumor suppressor p53 is an activator of cell growth arrest and apoptosis-mediator genes such as p21, Bax, and GADD45 in MCF-7As53 cells, no alterations in expression levels of these genes were detected. The doubling time of these cells decreased due to depletion of G0/G1 cell phase because of constitutive activation of Akt and increase in cyclin D1 protein levels. This proliferative property was abrogated by wortmannin, an inhibitor of PI3-K/Akt signaling pathway. Therefore this p53 null cell line indicates that p53 is an indispensable component of cellular signaling system which is regulated by caveolin-1 expression, involving Akt activation and increase in cyclin D1, thereby promoting proliferation of breast cancer cells.« less

The expanding universe of p53 targets.

PubMed

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

2009-10-01

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

An Old Story Retold: Loss of G1 Control Defines A Distinct Genomic Subtype of Esophageal Squamous Cell Carcinoma.

PubMed

Wang, Qiyan; Bai, Jian; Abliz, Amir; Liu, Ying; Gong, Kenan; Li, Jingjing; Shi, Wenjie; Pan, Yaqi; Liu, Fangfang; Lai, Shujuan; Yang, Haijun; Lu, Changdong; Zhang, Lixin; Chen, Wei; Xu, Ruiping; Cai, Hong; Ke, Yang; Zeng, Changqing

2015-08-01

Esophageal squamous cell carcinoma (ESCC) has a high mortality rate. To determine the molecular basis of ESCC development, this study sought to identify characteristic genome-wide alterations in ESCC, including exonic mutations and structural alterations. The clinical implications of these genetic alterations were also analyzed. Exome sequencing and verification were performed for nine pairs of ESCC and the matched blood samples, followed by validation with additional samples using Sanger sequencing. Whole-genome SNP arrays were employed to detect copy number alteration (CNA) and loss of heterozygosity (LOH) in 55 cases, including the nine ESCC samples subjected to exome sequencing. A total of 108 non-synonymous somatic mutations (NSSMs) in 102 genes were verified in nine patients. The chromatin modification process was found to be enriched in our gene ontology (GO) analysis. Tumor genomes with TP53 mutations were significantly more unstable than those without TP53 mutations. In terms of the landscape of genomic alterations, deletion of 9p21.3 covering CDKN2A/2B (30.9%), amplification of 11q13.3 covering CCND1 (30.9%), and TP53 point mutation (50.9%) occurred in two-thirds of the cases. These results suggest that the deregulation of the G1 phase during the cell cycle is a key event in ESCC. Furthermore, six minimal common regions were found to be significantly altered in ESCC samples and three of them, 9p21.3, 7p11.2, and 3p12.1, were associated with lymph node metastasis. With the high correlation of TP53 mutation and genomic instability in ESCC, the amplification of CCND1, the deletion of CDKN2A/2B, and the somatic mutation of TP53 appear to play pivotal roles via G1 deregulation and therefore helps to classify this cancer into different genomic subtypes. These findings provide clinical significance that could be useful in future molecular diagnoses and therapeutic targeting. Copyright © 2015 The Authors. Production and hosting by Elsevier Ltd.. All rights reserved.

Prevention of the neurocristopathy Treacher Collins syndrome through inhibition of p53 function

PubMed Central

Jones, Natalie C; Lynn, Megan L; Gaudenz, Karin; Sakai, Daisuke; Aoto, Kazushi; Rey, Jean-Phillipe; Glynn, Earl F; Ellington, Lacey; Du, Chunying; Dixon, Jill; Dixon, Michael J; Trainor, Paul A

2010-01-01

Treacher Collins syndrome (TCS) is a congenital disorder of craniofacial development arising from mutations in TCOF1, which encodes the nucleolar phosphoprotein Treacle. Haploinsufficiency of Tcof1 perturbs mature ribosome biogenesis, resulting in stabilization of p53 and the cyclin G1–mediated cell-cycle arrest that underpins the specificity of neuroepithelial apoptosis and neural crest cell hypoplasia characteristic of TCS. Here we show that inhibition of p53 prevents cyclin G1–driven apoptotic elimination of neural crest cells while rescuing the craniofacial abnormalities associated with mutations in Tcof1 and extending life span. These improvements, however, occur independently of the effects on ribosome biogenesis; thus suggesting that it is p53-dependent neuroepithelial apoptosis that is the primary mechanism underlying the pathogenesis of TCS. Our work further implies that neuroepithelial and neural crest cells are particularly sensitive to cellular stress during embryogenesis and that suppression of p53 function provides an attractive avenue for possible clinical prevention of TCS craniofacial birth defects and possibly those of other neurocristopathies. PMID:18246078

p53−/− synergizes with enhanced NrasG12D signaling to transform megakaryocyte-erythroid progenitors in acute myeloid leukemia

PubMed Central

Kong, Guangyao; Rajagopalan, Adhithi; Lu, Li; Song, Jingming; Hussaini, Mohamed; Zhang, Xinmin; Ranheim, Erik A.; Liu, Yangang; Wang, Jinyong; Gao, Xin; Chang, Yuan-I; Johnson, Kirby D.; Zhou, Yun; Yang, David; Bhatnagar, Bhavana; Lucas, David M.; Bresnick, Emery H.; Zhong, Xuehua; Padron, Eric

2017-01-01

Somatic mutations in TP53 and NRAS are associated with transformation of human chronic myeloid diseases to acute myeloid leukemia (AML). Here, we report that concurrent RAS pathway and TP53 mutations are identified in a subset of AML patients and confer an inferior overall survival. To further investigate the genetic interaction between p53 loss and endogenous NrasG12D/+ in AML, we generated conditional NrasG12D/+p53−/− mice. Consistent with the clinical data, recipient mice transplanted with NrasG12D/+p53−/− bone marrow cells rapidly develop a highly penetrant AML. We find that p53−/− cooperates with NrasG12D/+ to promote increased quiescence in megakaryocyte-erythroid progenitors (MEPs). NrasG12D/+p53−/− MEPs are transformed to self-renewing AML-initiating cells and are capable of inducing AML in serially transplanted recipients. RNA sequencing analysis revealed that transformed MEPs gain a partial hematopoietic stem cell signature and largely retain an MEP signature. Their distinct transcriptomes suggests a potential regulation by p53 loss. In addition, we show that during AML development, transformed MEPs acquire overexpression of oncogenic Nras, leading to hyperactivation of ERK1/2 signaling. Our results demonstrate that p53−/− synergizes with enhanced oncogenic Nras signaling to transform MEPs and drive AML development. This model may serve as a platform to test candidate therapeutics in this aggressive subset of AML. PMID:27815262

Pharmacological targeting of p53 through RITA is an effective antitumoral strategy for malignant pleural mesothelioma.

PubMed

Di Marzo, Domenico; Forte, Iris Maria; Indovina, Paola; Di Gennaro, Elena; Rizzo, Valeria; Giorgi, Francesca; Mattioli, Eliseo; Iannuzzi, Carmelina Antonella; Budillon, Alfredo; Giordano, Antonio; Pentimalli, Francesca

2014-01-01

Malignant mesothelioma, a very aggressive tumor associated to asbestos exposure, is expected to increase in incidence, and unfortunately, no curative modality exists. Reactivation of p53 is a new attractive antitumoral strategy. p53 is rarely mutated in mesothelioma, but it is inactivated in most tumors by the lack of p14(ARF). Here, we evaluated the feasibility of this approach in pleural mesothelioma by testing RITA and nutlin-3, two molecules able to restore p53 function through a different mechanism, on a panel of mesothelioma cell lines representing the epithelioid (NCI-H28, NCI-H2452, IST-MES 2), biphasic (MSTO-211H), and sarcomatoid (NCI-H2052) histotypes compared with the normal mesothelial HMC-hTERT. RITA triggered robust caspase-dependent apoptosis specifically in epithelioid and biphasic mesothelioma cell lines, both through wild-type and mutant p53, concomitant to p21 downregulation. Conversely, nutlin-3 induced a p21-dependent growth arrest, rather than apoptosis, and was slightly toxic on HMC-hTERT.   Interestingly, we identified a previously undetected point mutation of p53 (p.Arg249Ser) in IST-MES 2, and showed that RITA is also able to reactivate this p53 mutant protein and its apoptotic function. RITA reduced tumor growth in a MSTO-211H-derived xenograft model of mesothelioma and synergized with cisplatin, which is the mainstay of treatment for this tumor. Our data indicate that reactivation of p53 and concomitant p21 downregulation effectively induce cell death in mesothelioma, a tumor characterized by a high intrinsic resistance to apoptosis. Altogether, our findings provide the preclinical framework supporting the use of p53-reactivating agents alone, or in combination regimens, to improve the outcome of patients with mesothelioma.

Analysis of a p53 Mutation Associated with Cancer Susceptibility for Biochemistry and Genetic Laboratory Courses

ERIC Educational Resources Information Center

Soto-Cruz, Isabel; Legorreta-Herrera, Martha

2009-01-01

We have devised and implemented a module for an upper division undergraduate laboratory based on the amplification and analysis of a p53 polymorphism associated with cancer susceptibility. First, students collected a drop of peripheral blood cells using a sterile sting and then used FTA cards to extract the genomic DNA. The p53 region is then PCR…

Researchers Use a Kinome Screen to Identify New Therapeutic Targets | Office of Cancer Genomics

Cancer.gov

The tumor suppressor p53 is mutated in over 50% of head and neck squamous cell carcinomas (HNSCC), yet there are currently no available therapies to target it. CTD2 researchers at the Fred Hutchison Cancer Research Center hypothesized that HNSCC cancer cells with p53 mutations are dependent on particular kinases for survival. In a study published in Clinical Cancer Research, they sought to identify these kinases using RNAi against known kinase genes in mouse and human cell lines.

Friend or Foe: MicroRNAs in the p53 network.

PubMed

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

2018-04-10

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

Murine Gammaherpesvirus 68 LANA and SOX Homologs Counteract ATM-Driven p53 Activity during Lytic Viral Replication

PubMed Central

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

2015-01-01

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

Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents

PubMed Central

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

2012-01-01

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

Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents.

PubMed

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

2012-04-05

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

Depression of p53-independent Akt survival signals in human oral cancer cells bearing mutated p53 gene after exposure to high-LET radiation

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

Nakagawa, Yosuke; Takahashi, Akihisa; Kajihara, Atsuhisa

Highlights: Black-Right-Pointing-Pointer High-LET radiation induces efficiently apoptosis regardless of p53 gene status. Black-Right-Pointing-Pointer We examined whether high-LET radiation depresses the Akt-survival signals. Black-Right-Pointing-Pointer High-LET radiation depresses of survival signals even in the mp53 cancer cells. Black-Right-Pointing-Pointer High-LET radiation activates Caspase-9 through depression of survival signals. Black-Right-Pointing-Pointer High-LET radiation suppresses cell growth through depression of survival signals. -- Abstract: Although mutations and deletions in the p53 tumor suppressor gene lead to resistance to low linear energy transfer (LET) radiation, high-LET radiation efficiently induces cell lethality and apoptosis regardless of the p53 gene status in cancer cells. Recently, it has been suggestedmore » that the induction of p53-independent apoptosis takes place through the activation of Caspase-9 which results in the cleavage of Caspase-3 and poly (ADP-ribose) polymerase (PARP). This study was designed to examine if high-LET radiation depresses serine/threonine protein kinase B (PKB, also known as Akt) and Akt-related proteins. Human gingival cancer cells (Ca9-22 cells) harboring a mutated p53 (mp53) gene were irradiated with 2 Gy of X-rays or Fe-ion beams. The cellular contents of Akt-related proteins participating in cell survival signaling were analyzed with Western Blotting 1, 2, 3 and 6 h after irradiation. Cell cycle distributions after irradiation were assayed with flow cytometric analysis. Akt-related protein levels decreased when cells were irradiated with high-LET radiation. High-LET radiation increased G{sub 2}/M phase arrests and suppressed the progression of the cell cycle much more efficiently when compared to low-LET radiation. These results suggest that high-LET radiation enhances apoptosis through the activation of Caspase-3 and Caspase-9, and suppresses cell growth by suppressing Akt-related signaling, even in mp53 bearing cancer cells.« less

Requirement of the ATM/p53 tumor suppressor pathway for glucose homeostasis.

PubMed

Armata, Heather L; Golebiowski, Diane; Jung, Dae Young; Ko, Hwi Jin; Kim, Jason K; Sluss, Hayla K

2010-12-01

Ataxia telangiectasia (A-T) patients can develop multiple clinical pathologies, including neuronal degeneration, an elevated risk of cancer, telangiectasias, and growth retardation. Patients with A-T can also exhibit an increased risk of insulin resistance and type 2 diabetes. The ATM protein kinase, the product of the gene mutated in A-T patients (Atm), has been implicated in metabolic disease, which is characterized by insulin resistance and increased cholesterol and lipid levels, blood pressure, and atherosclerosis. ATM phosphorylates the p53 tumor suppressor on a site (Ser15) that regulates transcription activity. To test whether the ATM pathway that regulates insulin resistance is mediated by p53 phosphorylation, we examined insulin sensitivity in mice with a germ line mutation that replaces the p53 phosphorylation site with alanine. The loss of p53 Ser18 (murine Ser15) led to increased metabolic stress, including severe defects in glucose homeostasis. The mice developed glucose intolerance and insulin resistance. The insulin resistance correlated with the loss of antioxidant gene expression and decreased insulin signaling. N-Acetyl cysteine (NAC) treatment restored insulin signaling in late-passage primary fibroblasts. The addition of an antioxidant in the diet rendered the p53 Ser18-deficient mice glucose tolerant. This analysis demonstrates that p53 phosphorylation on an ATM site is an important mechanism in the physiological regulation of glucose homeostasis.

SNP array profiling of childhood adrenocortical tumors reveals distinct pathways of tumorigenesis and highlights candidate driver genes.

PubMed

Letouzé, Eric; Rosati, Roberto; Komechen, Heloisa; Doghman, Mabrouka; Marisa, Laetitia; Flück, Christa; de Krijger, Ronald R; van Noesel, Max M; Mas, Jean-Christophe; Pianovski, Mara A D; Zambetti, Gerard P; Figueiredo, Bonald C; Lalli, Enzo

2012-07-01

Childhood adrenocortical tumors (ACT) are rare malignancies, except in southern Brazil, where a higher incidence rate is associated to a high frequency of the founder R337H TP53 mutation. To date, copy number alterations in these tumors have only been analyzed by low-resolution comparative genomic hybridization. We analyzed an international series of 25 childhood ACT using high-resolution single nucleotide polymorphism arrays to: 1) detect focal copy number alterations highlighting candidate driver genes; and 2) compare genetic alterations between Brazilian patients carrying the R337H TP53 mutation and non-Brazilian patients. We identified 16 significantly recurrent chromosomal alterations (q-value < 0.05), the most frequent being -4q34, +9q33-q34, +19p, loss of heterozygosity (LOH) of chromosome 17 and 11p15. Focal amplifications and homozygous deletions comprising well-known oncogenes (MYC, MDM2, PDGFRA, KIT, MCL1, BCL2L1) and tumor suppressors (TP53, RB1, RPH3AL) were identified. In addition, eight focal deletions were detected at 4q34, defining a sharp peak region around the noncoding RNA LINC00290 gene. Although non-Brazilian tumors with a mutated TP53 were similar to Brazilian tumors, those with a wild-type TP53 displayed distinct genomic profiles, with significantly fewer rearrangements (P = 0.019). In particular, three alterations (LOH of chromosome 17, +9q33-q34, and -4q34) were significantly more frequent in TP53-mutated samples. Finally, two of four TP53 wild-type tumors displayed as sole rearrangement a copy-neutral LOH of the imprinted region at 11p15, supporting a major role for this region in ACT development. Our findings highlight potential driver genes and cellular pathways implicated in childhood ACT and demonstrate the existence of different oncogenic routes in this pathology.

Cell-Intrinsic Determinants of Ibrutinib-Induced Apoptosis in Chronic Lymphocytic Leukemia.

PubMed

Amin, Nisar A; Balasubramanian, Sriram; Saiya-Cork, Kamlai; Shedden, Kerby; Hu, Nan; Malek, Sami N

2017-02-15

Purpose: Ibrutinib, a Bruton tyrosine kinase (BTK) inhibitor, is approved for the treatment of relapsed chronic lymphocytic leukemia (CLL) and CLL with del17p. Mechanistically, ibrutinib interferes with B-cell receptor (BCR) signaling as well as multiple CLL cell-to-microenvironment interactions. Given the importance of ibrutinib in the management of CLL, a deeper understanding of factors governing sensitivity and resistance is warranted. Experimental Design: We studied 48 longitudinally sampled paired CLL samples, 42 of which were procured before and after standard CLL chemotherapies, and characterized them for well-studied CLL molecular traits as well as by whole-exome sequencing and SNP 6.0 array profiling. We exposed these samples to 0.25 to 5 μmol/L of ibrutinib ex vivo and measured apoptosis fractions as well as BCR signaling by immunoblotting. We disrupted TP53 in HG3, PGA1, and PG-EBV cell lines and measured BCR signaling and ibrutinib responses. Results: CLL samples demonstrated a surprisingly wide range of ex vivo sensitivities to ibrutinib, with IC 50 values ranging from 0.4 to 9.7 μmol/L. Unmutated IGVH status, elevated ZAP70 expression, and trisomy 12 were associated with heightened sensitivity to ibrutinib treatment. Five CLL samples were substantially more resistant to ibrutinib following relapse from chemotherapy; of these, three had acquired a del17p/ TP53 -mutated status. A validation sample of 15 CLL carrying TP53 mutations, of which 13 carried both del17p and a TP53 mutation, confirmed substantially less sensitivity to ibrutinib-induced apoptosis. Conclusions: This study identifies that CLL harboring del17p/ TP53 -mutated cells are substantially less sensitive to ibrutinib-induced apoptosis than del17p/ TP53 wild-type cells. Clin Cancer Res; 23(4); 1049-59. ©2016 AACR . ©2016 American Association for Cancer Research.

Chromosome aberrations detected by conventional karyotyping using novel mitogens in chronic lymphocytic leukemia: Clinical and biologic correlations.

PubMed

Rigolin, Gian Matteo; del Giudice, Ilaria; Formigaro, Luca; Saccenti, Elena; Martinelli, Sara; Cavallari, Maurizio; Lista, Enrico; Tammiso, Elisa; Volta, Eleonora; Lupini, Laura; Bassi, Cristian; Bardi, Antonella; Sofritti, Olga; Daghia, Giulia; Cavazzini, Francesco; Marinelli, Marilisa; Tavolaro, Simona; Guarini, Anna; Negrini, Massimo; Foà, Robin; Cuneo, Antonio

2015-12-01

To clarify whether karyotype aberrations (KA) involving regions not covered by the standard fluorescence in situ hybridization (FISH) panel have independent prognostic relevance, we evaluated KA by conventional cytogenetics in a learning cohort (LC; n = 166) and a validation cohort (VC; n = 250) of untreated chronic lymphocytic leukemia (CLL) patients. In the VC, novel mitogens were used to improve metaphase generation and TP53, NOTCH1, and SF3B1 mutations were assessed. KA undetected by FISH were found in 35 and 35% of the cases in the LC and VC, respectively. In addition to FISH, KA allowed reclassification of 23 and 26% of cases in the LC and VC, respectively, into a higher cytogenetic risk group. By multivariate analysis, both in the LC and VC, KA other than isolated 13q deletion correlated with a shorter time to first treatment (TFT; P < 0.001 and 0.003, respectively), while a complex karyotype predicted a worse overall survival (OS, P = 0.015 and 0.010, respectively). In the VC, where a comprehensive biologic assessment was performed, a shorter TFT was also predicted by stage (P < 0.001), IGHV mutational status (P = 0.05), and del(17p)/TP53 mutations (P = 0.033) while stage (P = 0.023) and del(17p)/TP53 mutations (P = 0.024) independently predicted a shorter OS. FISH results did not independently impact on TFT and OS, in the LC and VC cohorts; this was also the case for NOTCH1 and SF3B1 mutations in the VC. We suggest that in CLL, conventional karyotyping with novel mitogens could be more effective than FISH for the detection of KA allowing for a more precise refinement of prognosis. © 2015 Wiley Periodicals, Inc.

Undifferentiated and Dedifferentiated Endometrial Carcinomas With POLE Exonuclease Domain Mutations Have a Favorable Prognosis.

PubMed

Espinosa, Iñigo; Lee, Cheng-Han; D'Angelo, Emanuela; Palacios, José; Prat, Jaime

2017-08-01

POLE exonuclease domain mutations have recently been described in undifferentiated endometrial carcinoma but, because of the rarity of this aggressive type of endometrial cancer, their prognostic significance is unknown. We have analyzed the immunophenotype (ARID1A, MLH1, PMS2, MSH2, MSH6, p53, β-catenin, and SMARCB1) and mutational status (POLE, PIK3CA, and PTEN) of 21 undifferentiated carcinomas (8 undifferentiated and 13 dedifferentiated carcinomas). Loss of ARID1A expression was observed in 9 of 19 cases (47%), loss of expression of at least 1 DNA mismatch repair protein in 7 (7/21; 33%), and p53 immunoreaction was aberrant (mutated/inactivated) in 11 cases (11/21; 52%). All tumors were negative for β-catenin. Normal nuclear SMARCB1 (INI1) staining was found in all but 1 dedifferentiated case. Two undifferentiated and 7 dedifferentiated carcinomas showed POLE exonuclease domain mutations (9/21; 42%). PIK3CA mutations occurred in six tumors (6/21; 28%) (2 undifferentiated and 4 dedifferentiated carcinomas). PTEN mutations were found in 7 of 15 cases (47%) (4 undifferentiated and 3 dedifferentiated carcinomas). POLE-mutated undifferentiated and dedifferentiated endometrial carcinomas were more frequently stage I tumors than similar carcinomas lacking exonuclease domain mutations (7/9; 78% vs. 3/12; 25%; P=0.023) and patients had significantly better outcome (disease-specific survival) than those without POLE exonuclease domain mutations (P=0.02). Determination of the POLE mutation status is important for the management of these patients.

BRCA1, TP53, and CHEK2 germline mutations in uterine serous carcinoma.

PubMed

Pennington, Kathryn P; Walsh, Tom; Lee, Ming; Pennil, Christopher; Novetsky, Akiva P; Agnew, Kathy J; Thornton, Anne; Garcia, Rochelle; Mutch, David; King, Mary-Claire; Goodfellow, Paul; Swisher, Elizabeth M

2013-01-15

Uterine serous carcinoma (USC) is not recognized as part of any defined hereditary cancer syndrome, and its association with hereditary breast and ovarian carcinoma and Lynch syndrome are uncertain. Using targeted capture and massively parallel genomic sequencing, 151 subjects with USC were assessed for germline mutations in 30 tumor suppressor genes, including BRCA1 (breast cancer 1, early onset), BRCA2, the DNA mismatch repair genes (MLH1 [mutL homolog 1], MSH2 [mutS homolog 2], MSH6, PMS2 [postmeiotic segregation increased 2]), TP53 (tumor protein p53), and 10 other genes in the Fanconi anemia-BRCA pathway. Ten cases with < 10% serous histology were also assessed. Seven subjects (4.6%) carried germline loss-of-function mutations: 3 subjects (2.0%) with mutations in BRCA1, 2 subjects (1.3%) with mutations in TP53, and 2 subjects (1.3%) with mutations in CHEK2 (checkpoint kinase 2). One subject with < 10% serous histology had an MSH6 mutation. Subjects with MSH6 and TP53 mutations had neither personal nor family histories suggestive of Lynch or Li-Fraumeni syndromes. Of the 22 women with USC and a personal history of breast carcinoma, the frequency of BRCA1 mutations was 9%, compared to 0.9% in 119 women with no such history. Approximately 5% of women with USC have germline mutations in 3 different tumor suppressor genes: BRCA1, CHEK2, and TP53. Mutations in DNA mismatch repair genes that cause Lynch syndrome are rare in USC. The germline BRCA1 mutation rate in USC subjects of 2% is higher than expected in a nonfounder population, suggesting that USC is associated with hereditary breast and ovarian carcinoma in a small proportion of cases. Women with USC and breast cancer should be offered genetic testing for BRCA1 and BRCA2 mutations. Copyright © 2012 American Cancer Society.

Tumour suppressor protein p53 regulates the stress activated bilirubin oxidase cytochrome P450 2A6

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

Hu, Hao, E-mail: hao.hu1@uqconnect.edu.au; Yu, Ting, E-mail: t.yu2@uq.edu.au; Arpiainen, Satu, E-mail: Satu.Juhila@orion.fi

2015-11-15

Human cytochrome P450 (CYP) 2A6 enzyme has been proposed to play a role in cellular defence against chemical-induced oxidative stress. The encoding gene is regulated by various stress activated transcription factors. This paper demonstrates that p53 is a novel transcriptional regulator of the gene. Sequence analysis of the CYP2A6 promoter revealed six putative p53 binding sites in a 3 kb proximate promoter region. The site closest to transcription start site (TSS) is highly homologous with the p53 consensus sequence. Transfection with various stepwise deletions of CYP2A6-5′-Luc constructs – down to − 160 bp from the TSS – showed p53 responsivenessmore » in p53 overexpressed C3A cells. However, a further deletion from − 160 to − 74 bp, including the putative p53 binding site, totally abolished the p53 responsiveness. Electrophoretic mobility shift assay with a probe containing the putative binding site showed specific binding of p53. A point mutation at the binding site abolished both the binding and responsiveness of the recombinant gene to p53. Up-regulation of the endogenous p53 with benzo[α]pyrene – a well-known p53 activator – increased the expression of the p53 responsive positive control and the CYP2A6-5′-Luc construct containing the intact p53 binding site but not the mutated CYP2A6-5′-Luc construct. Finally, inducibility of the native CYP2A6 gene by benzo[α]pyrene was demonstrated by dose-dependent increases in CYP2A6 mRNA and protein levels along with increased p53 levels in the nucleus. Collectively, the results indicate that p53 protein is a regulator of the CYP2A6 gene in C3A cells and further support the putative cytoprotective role of CYP2A6. - Highlights: • CYP2A6 is an immediate target gene of p53. • Six putative p53REs located on 3 kb proximate CYP2A6 promoter region. • The region − 160 bp from TSS is highly homologous with the p53 consensus sequence. • P53 specifically bind to the p53RE on the − 160 bp region. • HNF4α may interact with p53 in regulating CYP2A6 expression.« less

Noninvasive detection of activating estrogen receptor 1 (ESR1) mutations in estrogen receptor-positive metastatic breast cancer.

PubMed

Guttery, David S; Page, Karen; Hills, Allison; Woodley, Laura; Marchese, Stephanie D; Rghebi, Basma; Hastings, Robert K; Luo, Jinli; Pringle, J Howard; Stebbing, Justin; Coombes, R Charles; Ali, Simak; Shaw, Jacqueline A

2015-07-01

Activating mutations in the estrogen receptor 1 (ESR1) gene are acquired on treatment and can drive resistance to endocrine therapy. Because of the spatial and temporal limitations of needle core biopsies, our goal was to develop a highly sensitive, less invasive method of detecting activating ESR1 mutations via circulating cell-free DNA (cfDNA) and tumor cells as a "liquid biopsy." We developed a targeted 23-amplicon next-generation sequencing (NGS) panel for detection of hot-spot mutations in ESR1, phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA), tumor protein p53 (TP53), fibroblast growth factor receptor 1 (FGFR1), and fibroblast growth factor receptor 2 (FGFR2) in 48 patients with estrogen receptor-α-positive metastatic breast cancer who were receiving systemic therapy. Selected mutations were validated using droplet digital PCR (ddPCR). Nine baseline cfDNA samples had an ESR1 mutation. NGS detected 3 activating mutations in ESR1, and 3 hot-spot mutations in PIK3CA, and 3 in TP53 in baseline cfDNA, and the ESR1 p.D538G mutation in 1 matched circulating tumor cell sample. ddPCR analysis was more sensitive than NGS and identified 6 additional baseline cfDNA samples with the ESR1 p.D538G mutation at a frequency of <1%. In serial blood samples from 11 patients, 4 showed changes in cfDNA, 2 with emergence of a mutation in ESR1. We also detected a low frequency ESR1 mutation (1.3%) in cfDNA of 1 primary patient who was thought to have metastatic disease but was clear by scans. Early identification of ESR1 mutations by liquid biopsy might allow for cessation of ineffective endocrine therapies and switching to other treatments, without the need for tissue biopsy and before the emergence of metastatic disease. © 2015 American Association for Clinical Chemistry.

Selective FLT3 inhibitor FI-700 neutralizes Mcl-1 and enhances p53-mediated apoptosis in AML cells with activating mutations of FLT3 through Mcl-1/Noxa axis.

PubMed

Kojima, K; Konopleva, M; Tsao, T; Andreeff, M; Ishida, H; Shiotsu, Y; Jin, L; Tabe, Y; Nakakuma, H

2010-01-01

Treatment using Fms-like tyrosine kinase-3 (FLT3) inhibitors is a promising approach to overcome the dismal prognosis of acute myeloid leukemia (AML) with activating FLT3 mutations. Current trials are combining FLT3 inhibitors with p53-activating conventional chemotherapy. The mechanisms of cytotoxicity of FLT3 inhibitors are poorly understood. We investigated the interaction of FLT3 and p53 pathways after their simultaneous blockade using the selective FLT3 inhibitor FI-700 and the MDM2 inhibitor Nutlin-3 in AML. We found that FI-700 immediately reduced antiapoptotic Mcl-1 levels and enhanced Nutlin-induced p53-mediated mitochondrial apoptosis in FLT3/internal tandem duplication cells through the Mcl-1/Noxa axis. FI-700 induced proteasome-mediated degradation of Mcl-1, resulting in the reduced ability of Mcl-1 to sequester proapoptotic Bim. Nutlin-3 induced Noxa, which displaced Bim from Mcl-1. The FI-700/Nutlin-3 combination profoundly activated Bax and induced apoptosis. Our findings suggest that FI-700 actively enhances p53 signaling toward mitochondrial apoptosis and that a combination strategy aimed at inhibiting FLT3 and activating p53 signaling could potentially be effective in AML.

Oncogenic collaboration of the cyclin D1 (PRAD1, bcl-1) gene with a mutated p53 and an activated ras oncogene in neoplastic transformation.

PubMed

Uchimaru, K; Endo, K; Fujinuma, H; Zukerberg, L; Arnold, A; Motokura, T

1996-05-01

Cyclin D1 is one of the key regulators in G1 progression in the cell cycle and is also a candidate oncogene (termed PRAD1 or bcl-1) in several types of human tumors. We report a collaboration of the cyclin D1 gene with ras and a mutated form of p53 (p53-mt) in neoplastic transformation. Transfection of cyclin D1 alone or in combination with ras or with p53-mt was not sufficient for focus formation of rat embryonic fibroblasts. However, focus formation induced by co-transfection of ras and p53-mt was enhanced in the presence of the cyclin D1-expression plasmid. Co-transfection of ras- and p53-mt-transformants with the cyclin D1-expression plasmid resulted in reduced serum dependency in vitro. Furthermore, the transformants expressing exogenous cyclin D1 grew faster than those without the cyclin D1 plasmid when injected into nude mice. These observations strengthen the significance of cyclin D1 overexpression through gene rearrangement or gene amplification observed in human tumors as a step in multistep oncogenesis; deregulated expression of cyclin D1 may reduce the requirement for growth factors and may stimulate in vivo growth.

Functional kinomics identifies candidate therapeutic targets in head and neck cancer

PubMed Central

Moser, Russell; Xu, Chang; Kao, Michael; Annis, James; Lerma, Luisa Angelica; Schaupp, Christopher M.; Gurley, Kay E.; Jang, In Sock; Biktasova, Asel; Yarbrough, Wendell G.; Margolin, Adam A.; Grandori, Carla; Kemp, Christopher J.; Méndez, Eduardo

2014-01-01

Purpose To identify novel therapeutic drug targets for p53 mutant head and neck squamous cell carcinoma (HNSCC). Experimental Design RNAi kinome viability screens were performed on HNSCC cells including autologous pairs from primary tumor and recurrent/metastatic lesions, and in parallel on murine squamous cell carcinoma (MSCC) cells derived from tumors of inbred mice bearing germline mutations in Trp53, and p53 regulatory genes: Atm, Prkdc, and p19Arf. Cross-species analysis of cell lines stratified by p53 mutational status and metastatic phenotype was utilized to select 38 kinase targets. Both primary and secondary RNAi validation assays were performed on additional HNSCC cell lines to credential these kinase targets utilizing multiple phenotypic endpoints. Kinase targets were also examined via chemical inhibition utilizing a panel of kinase inhibitors. A preclinical study was conducted on the WEE1 kinase inhibitor, MK-1775. Results Our functional kinomics approach identified novel survival kinases in HNSCC involved in G2/M cell cycle checkpoint, SFK, PI3K and FAK pathways. RNAi mediated knockdown and chemical inhibition of the WEE1 kinase with a specific inhibitor, MK-1775, had a significant effect on both viability and apoptosis. Sensitivity to the MK-1775 kinase inhibitor is in part determined by p53 mutational status, and due to unscheduled mitotic entry. MK-1775 displays single-agent activity and potentiates the efficacy of cisplatin in a p53 mutant HNSCC xenograft model. Conclusions WEE1 kinase is a potential therapeutic drug target for HNSCC. This study supports the application of a functional kinomics strategy to identify novel therapeutic targets for cancer. PMID:25125259

Functional kinomics identifies candidate therapeutic targets in head and neck cancer.

PubMed

Moser, Russell; Xu, Chang; Kao, Michael; Annis, James; Lerma, Luisa Angelica; Schaupp, Christopher M; Gurley, Kay E; Jang, In Sock; Biktasova, Asel; Yarbrough, Wendell G; Margolin, Adam A; Grandori, Carla; Kemp, Christopher J; Méndez, Eduardo

2014-08-15

To identify novel therapeutic drug targets for p53-mutant head and neck squamous cell carcinoma (HNSCC). RNAi kinome viability screens were performed on HNSCC cells, including autologous pairs from primary tumor and recurrent/metastatic lesions, and in parallel on murine squamous cell carcinoma (MSCC) cells derived from tumors of inbred mice bearing germline mutations in Trp53, and p53 regulatory genes: Atm, Prkdc, and p19(Arf). Cross-species analysis of cell lines stratified by p53 mutational status and metastatic phenotype was used to select 38 kinase targets. Both primary and secondary RNAi validation assays were performed on additional HNSCC cell lines to credential these kinase targets using multiple phenotypic endpoints. Kinase targets were also examined via chemical inhibition using a panel of kinase inhibitors. A preclinical study was conducted on the WEE1 kinase inhibitor, MK-1775. Our functional kinomics approach identified novel survival kinases in HNSCC involved in G2-M cell-cycle checkpoint, SFK, PI3K, and FAK pathways. RNAi-mediated knockdown and chemical inhibition of the WEE1 kinase with a specific inhibitor, MK-1775, had a significant effect on both viability and apoptosis. Sensitivity to the MK-1775 kinase inhibitor is in part determined by p53 mutational status, and due to unscheduled mitotic entry. MK-1775 displays single-agent activity and potentiates the efficacy of cisplatin in a p53-mutant HNSCC xenograft model. WEE1 kinase is a potential therapeutic drug target for HNSCC. This study supports the application of a functional kinomics strategy to identify novel therapeutic targets for cancer. ©2014 American Association for Cancer Research.

KRAS and DAXX/ATRX Gene Mutations Are Correlated with the Clinicopathological Features, Advanced Diseases, and Poor Prognosis in Chinese Patients with Pancreatic Neuroendocrine Tumors

PubMed Central

Yuan, Fei; Shi, Min; Ji, Jun; Shi, Hailong; Zhou, Chenfei; Yu, Yingyan; Liu, Bingya; Zhu, Zhenggang; Zhang, Jun

2014-01-01

Background and Aim: Pancreatic neuroendocrine tumor (pNET) is a clinically rare and heterogeneous group of tumors; its pharmacogenetic characteristics are not fully understood. This study was designed to examine the relationship between key gene variations and disease development and prognosis among Chinese patients with pNET. Methods: Various pNET associated genes such as DAXX/ATRX, KRAS, MEN1, PTEN, TSC2, SMAD4/DPC, TP53 and VHL were analyzed in high-throughput sequencing. The links between the gene mutations and the clinicopathological features and prognosis of the patients were determined. Results: The somatic mutation frequencies of the DAXX/ATRX, KRAS, MEN1, mTOR pathway genes (PTEN and TSC2), SMAD4/DPC, TP53, and VHL in Chinese pNET patients were 54.05%, 10.81%, 35.14%, 54.05%, 2.70%, 13.51%, and 40.54%, respectively, while the same figures in Caucasians pNET patients were 43%, 0%, 44%, 15%, 0%, 3%, and 0%, respectively. The numbers of mutated genes were from 0 to 6; 4 patients with more than 3 mutated genes had higher proliferation (Ki-67) index or nerve vascular invasion or organ involvement, but only 9 of 27 patients with 3 or few mutated genes had such features. Mutations in KRAS and DAXX/ATRX, but not other genes analyzed, were associated with a shortened survival. Conclusion: The mutation rates of these genes in Chinese pNET patients are different from those in Caucasians. A higher number of gene mutations and the DAXX/ATRX and KRAS gene mutations are correlated with a poor prognosis of patients with pNET. PMID:25210493

WIP1 deficiency inhibits HTLV-1 Tax oncogenesis: novel therapeutic prospects for treatment of ATL?

PubMed Central

2012-01-01

Attenuation of p53 activity appears to be a major step in Human T-lymphotropic virus type 1 (HTLV-1) Tax transformation. However, p53 genomic mutations are late and rather infrequent events in HTLV-1 induced Adult T cell leukemia (ATL). The paper by Zane et al. shows that a mediator of p53 activity, Wild-type p53-induced phosphatase 1 (Wip1), contributes to Tax-induced oncogenesis in a mouse model. Wip1 may therefore be a novel target for therapeutic approaches. PMID:23256570

KRAS Mutation as a Potential Prognostic Biomarker of Biliary Tract Cancers

PubMed Central

Yokoyama, Masaaki; Ohnishi, Hiroaki; Ohtsuka, Kouki; Matsushima, Satsuki; Ohkura, Yasuo; Furuse, Junji; Watanabe, Takashi; Mori, Toshiyuki; Sugiyama, Masanori

2016-01-01

BACKGROUND The aim of this study was to identify the unique molecular characteristics of biliary tract cancer (BTC) for the development of novel molecular-targeted therapies. MATERIALS AND METHODS We performed mutational analysis of KRAS, BRAF, PIK3CA, and FBXW7 and immunohistochemical analysis of EGFR and TP53 in 63 Japanese patients with BTC and retrospectively evaluated the association between the molecular characteristics and clinicopathological features of BTC. RESULTS KRAS mutations were identified in 9 (14%) of the 63 BTC patients; no mutations were detected within the analyzed regions of BRAF, PIK3CA, and FBXW7. EGFR overexpression was observed in 5 (8%) of the 63 tumors, while TP53 overexpression was observed in 48% (30/63) of the patients. Overall survival of patients with KRAS mutation was significantly shorter than that of patients with the wild-type KRAS gene (P = 0.005). By multivariate analysis incorporating molecular and clinicopathological features, KRAS mutations and lymph node metastasis were identified to be independently associated with shorter overall survival (KRAS, P = 0.004; lymph node metastasis, P = 0.015). CONCLUSIONS Our data suggest that KRAS mutation is a poor prognosis predictive biomarker for the survival in BTC patients. PMID:28008299

Expression of matrix metalloproteinase 1, matrix metalloproteinase 2, and matrix metalloproteinase 9 in carcinoma of the head and neck.

PubMed

Franchi, Alessandro; Santucci, Marco; Masini, Emanuela; Sardi, Iacopo; Paglierani, Milena; Gallo, Oreste

2002-11-01

Numerous reports have documented a direct involvement of matrix metalloproteinase (MMP) overexpression in the development and progression of head and neck squamous cell carcinoma (HNSCC). In this study, the authors examined whether the expression of MMPs in HNSCC is correlated with other steps involved in tumor growth and metastasis, like angiogenesis, activation the nitric oxide (NO) pathway, and alteration of the p53 tumor suppressor gene. MMP-1, MMP-2, and MMP-9 expression levels were examined immunohistochemically in samples from 43 patients with HNSCC. Microvessel density (MVD) was determined by immunostaining of endothelial cells with anti-CD31 monoclonal antibody. Inducible nitric oxide synthase (iNOS) activity and cyclic guanosine monophosphatate (cGMP) levels were assessed in fresh tumor samples, whereas exons 5-9 of the p53 gene were analyzed by reverse transcriptase-polymerase chain reaction, single-strand conformation polymorphism analysis and were sequenced. MMP-1 overexpression (>10% of tumor cells) was identified in 32 tumors (74.5%), whereas elevated levels of MMP-2 and MMP-9 were detected in 17 tumors (39.5%) each. Tumors with MMP-9 overexpression were characterized by significantly higher MVD (P = 0.05) and significantly higher iNOS activity and cGMP levels (P = 0.005 and P = 0.02, respectively). Moreover, p53 mutation was associated strongly with MMP-9 overexpression (P = 0.004). Conversely, no correlation was found between MMP-1 and MMP-2 expression, angiogenesis, iNOS activity, cGMP levels, and p53 mutation in this series. This study documents the existence of a correlation between MMP-9 expression, activity of the iNOS pathway, p53 status, and angiogenesis in patients with HNSCC. This raises the possibility that p53 mutation, which frequently is present in HNSCC, may result in increased angiogenesis and invasiveness related to increased nitric oxide and MMP production by tumor cells, ultimately contributing to tumor progression. Copyright 2002 American Cancer Society.

EMT and induction of miR-21 mediate metastasis development in Trp53-deficient tumours

PubMed Central

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

2012-01-01

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

Synthetically lethal nanoparticles for treatment of endometrial cancer

NASA Astrophysics Data System (ADS)

Ebeid, Kareem; Meng, Xiangbing; Thiel, Kristina W.; Do, Anh-Vu; Geary, Sean M.; Morris, Angie S.; Pham, Erica L.; Wongrakpanich, Amaraporn; Chhonker, Yashpal S.; Murry, Daryl J.; Leslie, Kimberly K.; Salem, Aliasger K.

2018-01-01

Uterine serous carcinoma, one of the most aggressive types of endometrial cancer, is characterized by poor outcomes and mutations in the tumour suppressor p53. Our objective was to engender synthetic lethality to paclitaxel (PTX), the frontline treatment for endometrial cancer, in tumours with mutant p53 and enhance the therapeutic efficacy using polymeric nanoparticles (NPs). First, we identified the optimal NP formulation through comprehensive analyses of release profiles and cellular-uptake and cell viability studies. Not only were PTX-loaded NPs superior to PTX in solution, but the combination of PTX-loaded NPs with the antiangiogenic molecular inhibitor BIBF 1120 (BIBF) promoted synthetic lethality specifically in cells with the loss-of-function (LOF) p53 mutation. In a xenograft model of endometrial cancer, this combinatorial therapy resulted in a marked inhibition of tumour progression and extended survival. Together, our data provide compelling evidence for future studies of BIBF- and PTX-loaded NPs as a therapeutic opportunity for LOF p53 cancers.

Somatic mutations in PIK3CA and activation of AKT in intraductal tubulopapillary neoplasms of the pancreas.

PubMed

Yamaguchi, Hiroshi; Kuboki, Yuko; Hatori, Takashi; Yamamoto, Masakazu; Shiratori, Keiko; Kawamura, Shunji; Kobayashi, Makio; Shimizu, Michio; Ban, Shinichi; Koyama, Isamu; Higashi, Morihiro; Shin, Nobuhiro; Ishida, Kazuyuki; Morikawa, Takanori; Motoi, Fuyuhiko; Unno, Michiaki; Kanno, Atsushi; Satoh, Kennichi; Shimosegawa, Tooru; Orikasa, Hideki; Watanabe, Tomoo; Nishimura, Kazuhiko; Harada, Youji; Furukawa, Toru

2011-12-01

Intraductal tubulopapillary neoplasm (ITPN) is a recently recognized rare variant of intraductal neoplasms of the pancreas. Molecular aberrations underlying the neoplasm remain unknown. We investigated somatic mutations in PIK3CA, PTEN, AKT1, KRAS, and BRAF. We also investigated aberrant expressions of phosphorylated AKT, phosphatase and tensin homolog (PTEN), tumor protein 53 (TP53), SMAD4, and CTNNB1 in 11 cases of ITPNs and compared these data with those of 50 cases of intraductal papillary mucinous neoplasm (IPMN), another distinct variant of pancreatic intraductal neoplasms. Mutations in PIK3CA were found in 3 of 11 ITPNs but not in IPMNs (P = 0.005; Fisher exact test). In contrast, mutations in KRAS were found in none of the ITPNs but were found in 26 of the 50 IPMNs (P = 0.001; Fisher exact test). PIK3CA mutations were associated with strong expression of phosphorylated AKT (P < 0.001; the Mann-Whitney U test). Moreover, the expression of phosphorylated AKT was apparent in most ITPNs but only in a few IPMNs (P < 0.001; the Mann-Whitney U test). Aberrant expressions of TP53, SMAD4, and CTNNB1 were not statistically different between these neoplasms. Mutations in PIK3CA and the expression of phosphorylated AKT were not associated with age, sex, tissue invasion, and patients' prognosis in ITPNs. These results indicate that activation of the phosphatidylinositol 3-kinase pathway may play a crucial role in ITPNs but not in IPMNs. In contrast, the mutation in KRAS seems to play a major role in IPMNs but not in ITPNs. The activated phosphatidylinositol 3-kinase pathway may be a potential target for molecular diagnosis and therapy of ITPNs.

Differentiation-induced skin cancer suppression by FOS, p53, and TACE/ADAM17

PubMed Central

Guinea-Viniegra, Juan; Zenz, Rainer; Scheuch, Harald; Jiménez, María; Bakiri, Latifa; Petzelbauer, Peter; Wagner, Erwin F.

2012-01-01

Squamous cell carcinomas (SCCs) are heterogeneous and aggressive skin tumors for which innovative, targeted therapies are needed. Here, we identify a p53/TACE pathway that is negatively regulated by FOS and show that the FOS/p53/TACE axis suppresses SCC by inducing differentiation. We found that epidermal Fos deletion in mouse tumor models or pharmacological FOS/AP-1 inhibition in human SCC cell lines induced p53 expression. Epidermal cell differentiation and skin tumor suppression were caused by a p53-dependent transcriptional activation of the metalloprotease TACE/ADAM17 (TNF-α–converting enzyme), a previously unknown p53 target gene that was required for NOTCH1 activation. Although half of cutaneous human SCCs display p53-inactivating mutations, restoring p53/TACE activity in mouse and human skin SCCs induced tumor cell differentiation independently of the p53 status. We propose FOS/AP-1 inhibition or p53/TACE reactivating strategies as differentiation-inducing therapies for SCCs. PMID:22772468

Recognition of Local DNA Structures by p53 Protein

PubMed Central

Brázda, Václav; Coufal, Jan

2017-01-01

p53 plays critical roles in regulating cell cycle, apoptosis, senescence and metabolism and is commonly mutated in human cancer. These roles are achieved by interaction with other proteins, but particularly by interaction with DNA. As a transcription factor, p53 is well known to bind consensus target sequences in linear B-DNA. Recent findings indicate that p53 binds with higher affinity to target sequences that form cruciform DNA structure. Moreover, p53 binds very tightly to non-B DNA structures and local DNA structures are increasingly recognized to influence the activity of wild-type and mutant p53. Apart from cruciform structures, p53 binds to quadruplex DNA, triplex DNA, DNA loops, bulged DNA and hemicatenane DNA. In this review, we describe local DNA structures and summarize information about interactions of p53 with these structural DNA motifs. These recent data provide important insights into the complexity of the p53 pathway and the functional consequences of wild-type and mutant p53 activation in normal and tumor cells. PMID:28208646

Myophosphorylase (PYGM) mutations determined by next generation sequencing in a cohort from Turkey with McArdle disease.

PubMed

Inal-Gültekin, Güldal; Toptaş-Hekimoğlu, Bahar; Görmez, Zeliha; Gelişin, Özlem; Durmuş, Hacer; Ergüner, Bekir; Demirci, Hüseyin; Sağıroğlu, Mahmut Ş; Parman, Yeşim; Deymeer, Feza; Yılmaz-Aydoğan, Hülya; Pençe, Sadrettin; Bekircan-Kurt, Can Ebru; Tan, Ersin; Erdem-Özdamar, Sevim; Üstek, Duran; Giger, Urs; Öztürk, Oğuz; Serdaroğlu-Oflazer, Piraye

2017-11-01

This study aimed to identify PYGM mutations in patients with McArdle disease from Turkey by next generation sequencing (NGS). Genomic DNA was extracted from the blood of the McArdle patients (n = 67) and unrelated healthy volunteers (n = 53). The PYGM gene was sequenced with NGS and the observed mutations were validated by direct Sanger sequencing. A diagnostic algorithm was developed for patients with suspected McArdle disease. A total of 16 deleterious PYGM mutations were identified, of which 5 were novel, including 1 splice-site donor, 1 frame-shift, and 3 non-synonymous variants. The p.Met1Val (27-patients/11-families) was the most common PYGM mutation, followed by p.Arg576* (6/4), c.1827+7A>G (5/4), c.772+2_3delTG (5/3), p.Phe710del (4/2), p.Lys754Asnfs (2/1), and p.Arg50* (1/1). A molecular diagnostic flowchart is proposed for the McArdle patients in Turkey, covering the 6 most common PYGM mutations found in Turkey as well as the most common mutation in Europe. The diagnostic algorithm may alleviate the need for muscle biopsies in 77.6% of future patients. A prevalence of any of the mutations to a geographical region in Turkey was not identified. Furthermore, the NGS approach to sequence the entire PYGM gene was successful in detecting a common missense mutation and discovering novel mutations in this population study. Copyright © 2017 Elsevier B.V. All rights reserved.

LATS2 tumour specific mutations and down-regulation of the gene in non-small cell carcinoma.

PubMed

Strazisar, Mojca; Mlakar, Vid; Glavac, Damjan

2009-06-01

LATS2 is a new member of the LATS tumour suppressor family. The human LATS2 gene is located at chromosome 13q11-12, a hot spot (67%) for loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). We screened 129 non-small cell lung cancer samples and 13 lung cancer cell lines, initially for mutations in the LATS2 gene and subsequently for mutations in P53 and K-RAS genes. Either polymorphisms or mutations were identified in over 50 percent of analysed tumours. A novel missense mutation, S1073R, and a large deletion of 8 amino acids in the PAPA-repeat region were detected in 9 and 2 NSCLC tumours, respectively. Those mutations were not identified in the 13 lung cancer cell lines. Mutations were tumour specific and were absent from adjacent normal tissue and healthy controls. Down-regulation of the LATS2 gene was observed in most NSCLC tumours but was not related to any mutation or polymorphism. Tumours with a LATS2 mutation often also harbour a P53 but not K-RAS gene mutation and were mostly in an advanced stage of development, with regional lymph node involvement.

Digital next-generation sequencing identifies low-abundance mutations in pancreatic juice samples collected from the duodenum of patients with pancreatic cancer and intraductal papillary mucinous neoplasms

PubMed Central

Yu, Jun; Sadakari, Yoshihiko; Shindo, Koji; Suenaga, Masaya; Brant, Aaron; Almario, Jose Alejandro Navarro; Borges, Michael; Barkley, Thomas; Fesharakizadeh, Shahriar; Ford, Madeline; Hruban, Ralph H; Shin, Eun Ji; Lennon, Anne Marie; Canto, Marcia Irene; Goggins, Michael

2017-01-01

Objective Secretin-stimulated pancreatic juice contains DNA shed from cells lining the pancreatic ducts. Genetic analysis of this fluid may form a test to detect pancreatic ductal neoplasia. Design We employed digital next-generation sequencing (‘digital NGS’) to detect low-abundance mutations in secretin-stimulated juice samples collected from the duodenum of subjects enrolled in Cancer of the Pancreas Screening studies at Johns Hopkins Hospital. For each juice sample, digital NGS necessitated 96 NGS reactions sequencing nine genes. The study population included 115 subjects (53 discovery, 62 validation) (1) with pancreatic ductal adenocarcinoma (PDAC), (2) intraductal papillary mucinous neoplasm (IPMN), (3) controls with non-suspicious pancreata. Results Cases with PDAC and IPMN were more likely to have mutant DNA detected in pancreatic juice than controls (both p<0.0001); mutant DNA concentrations were higher in patients with PDAC than IPMN (p=0.003) or controls (p<0.001). TP53 and/or SMAD4 mutations were commonly detected in juice samples from patients with PDAC and were not detected in controls (p<0.0001); mutant TP53/SMAD4 concentrations could distinguish PDAC from IPMN cases with 32.4% sensitivity, 100% specificity (area under the curve, AUC 0.73, p=0.0002) and controls (AUC 0.82, p<0.0001). Two of four patients who developed pancreatic cancer despite close surveillance had SMAD4/TP53 mutations from their cancer detected in juice samples collected over 1 year prior to their pancreatic cancer diagnosis when no suspicious pancreatic lesions were detected by imaging. Conclusions The detection in pancreatic juice of mutations important for the progression of low-grade dysplasia to high-grade dysplasia and invasive pancreatic cancer may improve the management of patients undergoing pancreatic screening and surveillance. PMID:27432539

Exonuclease mutations in DNA polymerase epsilon reveal replication strand specific mutation patterns and human origins of replication

PubMed Central

Shinbrot, Eve; Henninger, Erin E.; Weinhold, Nils; Covington, Kyle R.; Göksenin, A. Yasemin; Schultz, Nikolaus; Chao, Hsu; Doddapaneni, HarshaVardhan; Muzny, Donna M.; Gibbs, Richard A.; Sander, Chris; Pursell, Zachary F.

2014-01-01

Tumors with somatic mutations in the proofreading exonuclease domain of DNA polymerase epsilon (POLE-exo*) exhibit a novel mutator phenotype, with markedly elevated TCT→TAT and TCG→TTG mutations and overall mutation frequencies often exceeding 100 mutations/Mb. Here, we identify POLE-exo* tumors in numerous cancers and classify them into two groups, A and B, according to their mutational properties. Group A mutants are found only in POLE, whereas Group B mutants are found in POLE and POLD1 and appear to be nonfunctional. In Group A, cell-free polymerase assays confirm that mutations in the exonuclease domain result in high mutation frequencies with a preference for C→A mutation. We describe the patterns of amino acid substitutions caused by POLE-exo* and compare them to other tumor types. The nucleotide preference of POLE-exo* leads to increased frequencies of recurrent nonsense mutations in key tumor suppressors such as TP53, ATM, and PIK3R1. We further demonstrate that strand-specific mutation patterns arise from some of these POLE-exo* mutants during genome duplication. This is the first direct proof of leading strand-specific replication by human POLE, which has only been demonstrated in yeast so far. Taken together, the extremely high mutation frequency and strand specificity of mutations provide a unique identifier of eukaryotic origins of replication. PMID:25228659

Loss of nuclear p27 (CDKN1B/KIP1) in colorectal cancer is correlated with microsatellite instability and CIMP.

PubMed

Ogino, Shuji; Kawasaki, Takako; Kirkner, Gregory J; Yamaji, Taiki; Loda, Massimo; Fuchs, Charles S

2007-01-01

Downregulation of p27 (cyclin-dependent kinase inhibitor-1B, CDKN1B or KIP1) is caused by increased ubiquitin-mediated proteasomal degradation in colorectal cancer, and has been associated with poor prognosis. CpG island methylator phenotype (CIMP) is a phenotype of colorectal cancer with extensive promoter methylation, and associated with high degree of microsatellite instability (MSI-H) and BRAF mutations. We have recently shown that both CIMP and MSI-H are inversely associated with downregulation of p21 (CDKN1A or CIP1), another cyclin-dependent kinase inhibitor. However, no study to date has examined relationship between p27 and CIMP status in colorectal cancer. Using MethyLight assays, we measured DNA methylation in five CIMP-specific gene promoters {CACNA1G, CDKN2A (p16), CRABP1, MLH1 and NEUROG1} in 706 colorectal cancer samples obtained from two large prospective cohorts. Among the 706 tumors, 112 (16%) were CIMP-high tumors with >or=4/5 methylated promoters. We assessed p27 and p53 expressions by immunohistochemistry. Loss of nuclear p27 expression {observed in 231 tumors (33%)} was significantly associated with CIMP-high, MSI-H and BRAF mutations, and these associations were much more pronounced among p53-negative tumors than p53-positive tumors. When CIMP-high and non-CIMP-high tumors were stratified by MSI status (or KRAS and BRAF status), CIMP-high and MSI-H (but not BRAF mutations) were still significantly associated with nuclear p27 loss. Nuclear p27 loss did not appear to be directly related to CDKN2A (p16) methylation. We conclude that downregulation of nuclear p27 is associated with CIMP-high and MSI-H in colorectal cancer. These associations are stronger among p53 wild-type tumors, implying important interplay of p27 and p53 functions (or dysfunctions) in the development of various molecular subtypes of colorectal cancer.

Germline and somatic FGFR1 abnormalities in dysembryoplastic neuroepithelial tumors

PubMed Central

Rivera, Barbara; Gayden, Tenzin; Carrot-Zhang, Jian; Nadaf, Javad; Boshari, Talia; Faury, Damien; Zeinieh, Michele; Blanc, Romeo; Burk, David L.; Fahiminiya, Somayyeh; Bareke, Eric; Schüller, Ulrich; Monoranu, Camelia M.; Sträter, Ronald; Kerl, Kornelius; Niederstadt, Thomas; Kurlemann, Gerhard; Ellezam, Benjamin; Michalak, Zuzanna; Thom, Maria; Lockhart, Paul J.; Leventer, Richard J.; Ohm, Milou; MacGregor, Duncan; Jones, David; Karamchandani, Jason; Greenwood, Celia MT; Berghuis, Albert M.; Bens, Susanne; Siebert, Reiner; Zakrzewska, Magdalena; Liberski, Pawel P.; Zakrzewski, Krzysztof; Sisodiya, Sanjay M.; Paulus, Werner; Albrecht, Steffen; Hasselblatt, Martin; Jabado, Nada; Foulkes, William D; Majewski, Jacek

2016-01-01

Dysembryoplastic neuroepithelial tumor (DNET) is a benign brain tumor associated with intractable drug-resistant epilepsy. In order to identify underlying genetic alterations and molecular mechanisms, we examined three family members affected by multinodular DNETs as well as 100 sporadic tumors from 96 patients, which had been referred to us as DNETs. We performed whole-exome sequencing on 46 tumors and targeted sequencing for hotspot FGFR1 mutations and BRAF p.V600E was used on the remaining samples. FISH, copy number variation assays and Sanger sequencing were used to validate the findings. By whole exome sequencing of the familial cases, we identified a novel germline FGFR1 mutation, p.R661P. Somatic activating FGFR1 mutations (p.N546K or p.K656E) were observed in the tumor samples and further evidence for functional relevance was obtained by in silico modelling. The FGFR1 p.K656E mutation was confirmed to be in cis with the germline p.R661P variant. In 43 sporadic cases, in which the diagnosis of DNET could be confirmed on central blinded neuropathology review, FGFR1 alterations were also frequent and mainly comprised intragenic tyrosine kinase FGFR1 duplication and multiple mutants in cis (25/43; 58.1%) while BRAF p.V600E alterations were absent (0/43). In contrast, in 53 cases, in which the diagnosis of DNET was not confirmed, FGFR1 alterations were less common (10/53; 19%; p<0.0001) and hotspot BRAF p.V600E (12/53; 22.6%) (p<0.001) prevailed. We observed overexpression of phospho-ERK in FGFR1 p.R661P and p.N546K mutant expressing HEK293 cells as well as FGFR1 mutated tumor samples, supporting enhanced MAP kinase pathway activation under these conditions. In conclusion, constitutional and somatic FGFR1 alterations and MAP kinase pathway activation are key events in the pathogenesis of DNET. These findings point the way towards existing targeted therapies. PMID:26920151

Functional Analysis of Interactions Between 53BP1, BRCA1 and p53

DTIC Science & Technology

2004-07-01

deficiency synergize in tumorigenesis. Furthermore, the loss of a single 53BP1 allele enhances the susceptibility to cancer in the absence of p53. 14...specific antibodies against these sites and showed that at least two of them (S25 and S29) are phosphorylated in vivo by ATM, the kinase mutated in cancer ...characterized by chromosomal aberrations, genetic instability and cancer predisposition. +HU 153BP1 Fig. 5: Lack of 53BP1 prevents the efficient accumulation

Dedifferentiated endometrial carcinomas with neuroendocrine features: a clinicopathologic, immunohistochemical, and molecular genetic study.

PubMed

Espinosa, Iñigo; De Leo, Antonio; D'Angelo, Emanuela; Rosa-Rosa, Juan M; Corominas, Marina; Gonzalez, Alan; Palacios, José; Prat, Jaime

2018-02-01

Undifferentiated endometrial carcinoma is an aggressive type of uterine cancer, which is occasionally associated with a low-grade endometrioid carcinoma component. This combination is referred to as "dedifferentiated endometrioid endometrial carcinoma." Neuroendocrine expression may occur in undifferentiated endometrial carcinoma, but its significance in dedifferentiated endometrial carcinomas is unknown. To gain insight into the pathogenesis of these tumors we have analyzed the immunophenotype (ARID1A, MLH1, PMS2, MSH2, MSH6, p53, β-catenin, SMARCB1, synaptophysin, chromogranin A, and CD56) and mutational status (PTEN, KRAS, PIK3CA, TP53 and POLE) of 4 dedifferentiated endometrial carcinomas with strong and diffuse neuroendocrine expression. All tumors demonstrated neuroendocrine expression in ≥70% of the cells in the undifferentiated carcinoma areas. Loss of expression of at least 1 DNA mismatch repair protein was observed in 2 cases, and p53 immunoreaction was aberrant (mutated/inactivated) in one case. All carcinomas were negative for β-catenin and maintained nuclear SMARCB1 (INI1) and ARID1A expression. Three tumors shared identical endometrioid molecular profile (PTEN and/or PIK3CA mutations) in both components. One tumor had POLE exonuclease domain mutation in the undifferentiated component. In one case, TP53 mutation was found exclusively in the undifferentiated component. Two patients died with peritoneal carcinomatosis and abdominal metastases, respectively; one patient died of a renal failure without evidence of disease, and the last patient is alive and free of disease at 3.3 years. Dedifferentiated endometrial carcinomas with neuroendocrine features are clinically and molecularly heterogeneous tumors. Probably, these carcinomas might acquire undifferentiated phenotype through mutations in TP53 and POLE. Copyright © 2017 Elsevier Inc. All rights reserved.

Clinical multiplexed exome sequencing distinguishes adult oligodendroglial neoplasms from astrocytic and mixed lineage gliomas.

PubMed

Cryan, Jane B; Haidar, Sam; Ramkissoon, Lori A; Bi, Wenya Linda; Knoff, David S; Schultz, Nikolaus; Abedalthagafi, Malak; Brown, Loreal; Wen, Patrick Y; Reardon, David A; Dunn, Ian F; Folkerth, Rebecca D; Santagata, Sandro; Lindeman, Neal I; Ligon, Azra H; Beroukhim, Rameen; Hornick, Jason L; Alexander, Brian M; Ligon, Keith L; Ramkissoon, Shakti H

2014-09-30

Classifying adult gliomas remains largely a histologic diagnosis based on morphology; however astrocytic, oligodendroglial and mixed lineage tumors can display overlapping histologic features. We used multiplexed exome sequencing (OncoPanel) on 108 primary or recurrent adult gliomas, comprising 65 oligodendrogliomas, 28 astrocytomas and 15 mixed oligoastrocytomas to identify lesions that could enhance lineage classification. Mutations in TP53 (20/28, 71%) and ATRX (15/28, 54%) were enriched in astrocytic tumors compared to oligodendroglial tumors of which 4/65 (6%) had mutations in TP53 and 2/65 (3%) had ATRX mutations. We found that oligoastrocytomas harbored mutations in TP53 (80%, 12/15) and ATRX (60%, 9/15) at frequencies similar to pure astrocytic tumors, suggesting that oligoastrocytomas and astrocytomas may represent a single genetic or biological entity. p53 protein expression correlated with mutation status and showed significant increases in astrocytomas and oligoastrocytomas compared to oligodendrogliomas, a finding that also may facilitate accurate classification. Furthermore our OncoPanel analysis revealed that 15% of IDH1/2 mutant gliomas would not be detected by traditional IDH1 (p.R132H) antibody testing, supporting the use of genomic technologies in providing clinically relevant data. In all, our results demonstrate that multiplexed exome sequencing can support evaluation and classification of adult low-grade gliomas with a single clinical test.

Chromosome microduplication in somatic cells decreases the genetic stability of human reprogrammed somatic cells and results in pluripotent stem cells.

PubMed

Yu, Yang; Chang, Liang; Zhao, Hongcui; Li, Rong; Fan, Yong; Qiao, Jie

2015-05-12

Human pluripotent stem cells, including cloned embryonic and induced pluripotent stem cells, offer a limitless cellular source for regenerative medicine. However, their derivation efficiency is limited, and a large proportion of cells are arrested during reprogramming. In the current study, we explored chromosome microdeletion/duplication in arrested and established reprogrammed cells. Our results show that aneuploidy induced by somatic cell nuclear transfer technology is a key factor in the developmental failure of cloned human embryos and primary colonies from implanted cloned blastocysts and that expression patterns of apoptosis-related genes are dynamically altered. Overall, ~20%-53% of arrested primary colonies in induced plurpotent stem cells displayed aneuploidy, and upregulation of P53 and Bax occurred in all arrested primary colonies. Interestingly, when somatic cells with pre-existing chromosomal mutations were used as donor cells, no cloned blastocysts were obtained, and additional chromosomal mutations were detected in the resulting iPS cells following long-term culture, which was not observed in the two iPS cell lines with normal karyotypes. In conclusion, aneuploidy induced by the reprogramming process restricts the derivation of pluripotent stem cells, and, more importantly, pre-existing chromosomal mutations enhance the risk of genome instability, which limits the clinical utility of these cells.

Expression and mutational analysis of Cip/Kip family in early glottic cancer.

PubMed

Kim, D-K; Lee, J H; Lee, O J; Park, C H

2015-02-01

Genetic alteration of cyclin-dependent kinase inhibitors has been associated with carcinogenesis mechanisms in various organs. This study aimed to evaluate the expression and mutational analysis of Cip/Kip family cyclin-dependent kinase inhibitors (p21CIP1/WAF1, p27KIP1 and p57KIP2) in early glottic cancer. Expressions of Cip/Kip family and p53 were determined by quantitative reverse transcription polymerase chain reaction and densitometry. For the analysis of p21 inactivation, sequence alteration was assessed using single-strand conformational polymorphism polymerase chain reaction. Additionally, the inactivation mechanism of p27 and p57 were investigated using DNA methylation analysis. Reduced expression of p27 and p57 were detected in all samples, whereas the expression of p21 was incompletely down-regulated in 6 of 11 samples. Additionally, single-strand conformational polymorphism polymerase chain reaction analysis showed the p53 mutation at exon 6. Methylation of p27 and p57 was detected by DNA methylation assay. Our results suggest that the Cip/Kip family may have a role as a molecular mechanism of carcinogenesis in early glottic cancer.

Medulloblastoma, WNT-activated/SHH-activated: clinical impact of molecular analysis and histogenetic evaluation.

PubMed

Cambruzzi, Eduardo

2018-05-01

Medulloblastoma (MDB) is a small cell poorly differentiated embryonal tumor of the cerebellum, which more frequently compromises children. Overall prognosis is favorable, but dependent of stage, histopathological pattern and molecular group. Approximately 30% of the affected patients will die from the disease. WHO 2016 Classification of Tumors of the Central Nervous System (CNS) has been classified MDB into four principal groups: WNT-activated MDB, SHH-activated MDB, group 3 MDB, and group 4 MDB. WNT-activated MDB is associated to monosomy 6, CTNNB1, DDX3X and TP53 mutations, beta-catenin nuclear immunoexpression, and a better prognosis than SHH-activated MDB. WNT-activated tumors account approximately for 10% of cases of MDBs, and are thought to arise from cells in the dorsal brain stem/lower rhombic lip progenitor cells. SHH-activated MDB more frequently arises in the lateral hemispheres of the cerebellum, and clinical outcome in this group is variable. TP53-mutant SHHactivated MDB usually shows the large cell/anaplastic pattern, and can be related to MYCN amplification, GLI2 amplification and 17p loss. TP53-wildtype SHH-activated MDB is more commonly of desmoplastic/nodular morphology, and can be related to PTCH1 deletion and 10q loss. Gene expression and methylation profiling is the gold standard for defining molecular groups of MDB. In immunohistochemistry assays, anti-GAB1 antibody expression is positive in tumors showing SHH pathway activation or PTCH mutation, while positive immunoexpression for YAP1 antibody can be only found in WNT-activated and SHH-activated MDB.

Long-term response to sulfonylurea in a patient with diabetes due to mutation in the KCNJ11 gene.

PubMed

Vendramini, Marcio F; Gurgel, Lucimary C; Moisés, Regina S

2010-11-01

To report the long-term (30-month) effect of the switch from insulin to sulfonylurea in a patient carrying the p.G53D (c.158G>A) mutation in KCNJ11 gene. A 29-year-old male patient was diagnosed with diabetes in the third month of life and after identification of a heterozygous p.G53D mutation in the KCNJ11 gene, the therapy was switched from insulin to sulfonylurea. Long-term follow-up (30 months) showed that good metabolic control was maintained (HbA1c: 6.6%) and the glibenclamide dose could be reduced. Long-term therapy with sulfonylureas in patients with neonatal diabetes due to mutation in the KCNJ11 gene is safe and promotes sustained improvement of glycemic control.

Investigating DNA Binding and Conformational Variation in Temperature Sensitive p53 Cancer Mutants Using QM-MM Simulations

PubMed Central

Koulgi, Shruti; Achalere, Archana; Sonavane, Uddhavesh; Joshi, Rajendra

2015-01-01

The tp53 gene is found to be mutated in 50% of all the cancers. The p53 protein, a product of tp53 gene, is a multi-domain protein. It consists of a core DNA binding domain (DBD) which is responsible for its binding and transcription of downstream target genes. The mutations in p53 protein are responsible for creating cancerous conditions and are found to be occurring at a high frequency in the DBD region of p53. Some of these mutations are also known to be temperature sensitive (ts) in nature. They are known to exhibit partial or strong binding with DNA in the temperature range (298–306 K). Whereas, at 310 K and above they show complete loss in binding. We have analyzed the changes in binding and conformational behavior at 300 K and 310 K for three of the ts-mutants viz., V143A, R249S and R175H. QM-MM simulations have been performed on the wild type and the above mentioned ts-mutants for 30 ns each. The optimal estimate of free energy of binding for a particular number of interface hydrogen bonds was calculated using the maximum likelihood method as described by Chodera et. al (2007). This parameter has been observed to be able to mimic the binding affinity of the p53 ts-mutants at 300 K and 310 K. Thus the correlation between MM-GBSA free energy of binding and hydrogen bonds formed by the interface residues between p53 and DNA has revealed the temperature dependent nature of these mutants. The role of main chain dihedrals was obtained by performing dihedral principal component analysis (PCA). This analysis, suggests that the conformational variations in the main chain dihedrals (ϕ and ψ) of the p53 ts-mutants may have caused reduction in the overall stability of the protein. The solvent exposure of the side chains of the interface residues were found to hamper the binding of the p53 to the DNA. Solvent Accessible Surface Area (SASA) also proved to be a crucial property in distinguishing the conformers obtained at 300 K and 310 K for the three ts-mutants from the wild type at 300 K. PMID:26579714

Blocking angiotensin II Type 1 receptor triggers apoptotic cell death in human pancreatic cancer cells.

PubMed

Gong, Qiaoke; Davis, Molly; Chipitsyna, Galina; Yeo, Charles J; Arafat, Hwyda A

2010-07-01

Pancreatic ductal adenocarcinoma (PDA) is an aggressive malignancy with an annual mortality rate close to its annual incidence. We recently demonstrated that angiotensin II (AngII) type 1 receptor (AT1R) might be involved in PDA angiogenesis. This study evaluated the antiproliferative and proapoptotic effects of an AT1R blocker, losartan, in PDA cells with different p53 mutation status. Cell cycle was analyzed by flow cytometric analysis of DNA content; apoptosis by annexin V-fluorescein isothiocyanate (V-FITC) and terminal deoxytransferase (TdT)-mediated dUTP nick-end labeling staining; messenger RNA and protein by real-time polymerase chain reaction and Western blotting; caspase-3 activity by colorimetric assay; and promoter activity by luciferase assay. Losartan dose-dependently decreased cell survival and increased their preG1 accumulation. It also increased p53, p21, p27, and Bax and reduced Bcl-2 and Bcl-xl expression. In wtp53 cells, losartan increased p53 transcription and activated caspase-3 in both cell lines. However, its proapoptotic effects in mtp53 cells were mainly caspase-3-dependent. Our data describe the involvement of AT1R in PDA cell apoptotic machinery and provide the first evidences that losartan stimulates the proapoptotic signaling pathways regardless of the p53 mutation status. As loss of p53 function is frequently observed in PDA patients, our data suggest AT1R blockade as a novel therapeutic strategy to control PDA growth.

Loss of p53 protein during radiation transformation of primary human mammary epithelial cells

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

Wazer, D.E.; Chu, Qiuming; Liu, Xiao Long

1994-04-01

The causative factors leading to breast cancer are largely unknown. Increased incidence of breast cancer following diagnostic or therapeutic radiation suggests that radiation may contribute to mammary oncogenesis. This report describes the in vitro neoplastic transformation of a normal human mammary epithelial cell strain, 76N, by fractionated [gamma]-irradiation at a clinically used dose (30 Gy). The transformed cells (76R-30) were immortal, had reduced growth factor requirements, and produced tumors in nude mice. Remarkably, the 76R-30 cells completely lacked the p53 tumor suppressor protein. Loss of p53 was due to deletion of the gene on one allele and a 26-bp deletionmore » within the third intron on the second allele which resulted in abnormal splicing out of either the third or fourth exon from the mRNA. PCR with a mutation-specific primer showed that intron 3 mutation was present in irradiated cells before selection for immortal phenotype. 76R-30 cells did not exhibit G[sub 1] arrest in response to radiation, indicating a loss of p53-mediated function. Expression of the wild-type p53 gene in 76R-30 cells led to their growth inhibition. Thus, loss of p53 protein appears to have contributed to neoplastic transformation of these cells. This unique model should facilitate analyses of molecular mechanisms of radiation-induced breast cancer and allow identification of p53-regulated cellular genes in breast cells. 44 refs., 8 figs., 1 tab.« less

Mutant p53 expression in kidney tubules adjacent to renal cell carcinoma: evidence of a precursor lesion.

PubMed

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

1996-06-01

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

The p53–Mdm2 feedback loop protects against DNA damage by inhibiting p53 activity but is dispensable for p53 stability, development, and longevity

PubMed Central

Pant, Vinod; Xiong, Shunbin; Jackson, James G.; Post, Sean M.; Abbas, Hussein A.; Quintás-Cardama, Alfonso; Hamir, Amirali N.; Lozano, Guillermina

2013-01-01

The p53–Mdm2 feedback loop is perceived to be critical for regulating stress-induced p53 activity and levels. However, this has never been tested in vivo. Using a genetically engineered mouse with mutated p53 response elements in the Mdm2 P2 promoter, we show that feedback loop-deficient Mdm2P2/P2 mice are viable and aphenotypic and age normally. p53 degradation kinetics after DNA damage in radiosensitive tissues remains similar to wild-type controls. Nonetheless, DNA damage response is elevated in Mdm2P2/P2 mice. Enhanced p53-dependent apoptosis sensitizes hematopoietic stem cells (HSCs), causing drastic myeloablation and lethality. These results suggest that while basal Mdm2 levels are sufficient to regulate p53 in most tissues under homeostatic conditions, the p53–Mdm2 feedback loop is critical for regulating p53 activity and sustaining HSC function after DNA damage. Therefore, transient disruption of p53–Mdm2 interaction could be explored as a potential adjuvant/therapeutic strategy for targeting stem cells in hematological malignancies. PMID:23973961

Phosphorylation of p53 modifies sensitivity to ionizing radiation.

PubMed

Okaichi, Kumio; Nose, Kanako; Kotake, Takako; Izumi, Nanaka; Kudo, Takashi

2011-06-01

Phosphorylation is an important modification involved in the control of p53 activity. We examined the relationship between p53 phosphorylation and cell radiosensitivity. We prepared H1299 cells (p53-null) with various mutations of p53 at three sites (serine 15, 20 and 46) and examined the radiosensitivity of the cells. In three mutant forms of p53--S15A, S20A and S46A--serine was converted to alanine at these sites to prevent phosphorylation, and in two other mutant forms, S15D and S20D, serine was converted to aspartic acid to mimic phosphorylation. H1299 cells were more radioresistant than cells with wild-type p53. Cells with the S15A and S46A mutant forms of p53 were radiosensitive, whereas those with the S15D, S20A and S20D forms showed medium radiosensitivity. Thus the sensitivity of cells to ionizing radiation varies according to the site of phosphorylation of p53.

Molecular spectrum of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC somatic gene mutations in Arab patients with colorectal cancer: determination of frequency and distribution pattern

PubMed Central

Al-Shamsi, Humaid O.; Jones, Jeremy; Fahmawi, Yazan; Dahbour, Ibrahim; Tabash, Aziz; Abdel-Wahab, Reham; Abousamra, Ahmed O. S.; Shaw, Kenna R.; Xiao, Lianchun; Hassan, Manal M.; Kipp, Benjamin R.; Kopetz, Scott; Soliman, Amr S.; McWilliams, Robert R.; Wolff, Robert A.

2016-01-01

Background The frequency rates of mutations such as KRAS, NRAS, BRAF, and PIK3CA in colorectal cancer (CRC) differ among populations. The aim of this study was to assess mutation frequencies in the Arab population and determine their correlations with certain clinicopathological features. Methods Arab patients from the Arab Gulf region and a population of age- and sex-matched Western patients with CRC whose tumors were evaluated with next-generation sequencing (NGS) were identified and retrospectively reviewed. The mutation rates of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC were recorded, along with clinicopathological features. Other somatic mutation and their rates were also identified. Fisher’s exact test was used to determine the association between mutation status and clinical features. Results A total of 198 cases were identified; 99 Arab patients and 99 Western patients. Fifty-two point seven percent of Arab patients had stage IV disease at initial presentation, 74.2% had left-sided tumors. Eighty-nine point two percent had tubular adenocarcinoma and 10.8% had mucinous adenocarcinoma. The prevalence rates of KRAS, NRAS, BRAF, PIK3CA, TP53, APC, SMAD, FBXW7 mutations in Arab population were 44.4%, 4%, 4%, 13.1%, 52.5%, 27.3%, 2% and 3% respectively. Compared to 48.4%, 4%, 4%, 12.1%, 47.5%, 24.2%, 11.1% and 0% respectively in matched Western population. Associations between these mutations and patient clinicopathological features were not statistically significant. Conclusions This is the first study to report comprehensive hotspot mutations using NGS in Arab patients with CRC. The frequency of KRAS, NRAS, BRAF, TP53, APC and PIK3CA mutations were similar to reported frequencies in Western population except SMAD4 that had a lower frequency and higher frequency of FBXW7 mutation. PMID:28078112

Disruption of the RP-MDM2-p53 pathway accelerates APC loss-induced colorectal tumorigenesis.

PubMed

Liu, S; Tackmann, N R; Yang, J; Zhang, Y

2017-03-01

Inactivation of the adenomatous polyposis coli (APC) tumor suppressor is frequently found in colorectal cancer. Loss of APC function results in deregulation of the Wnt/β-catenin signaling pathway causing overexpression of the c-MYC oncogene. In lymphoma, both p19ARF and ribosomal proteins RPL11 and RPL5 respond to c-MYC activation to induce p53. Their role in c-MYC-driven colorectal carcinogenesis is unclear, as p19ARF deletion does not accelerate APC loss-triggered intestinal tumorigenesis. To determine the contribution of the ribosomal protein (RP)-murine double minute 2 (MDM2)-p53 pathway to APC loss-induced tumorigenesis, we crossed mice bearing MDM2 C305F mutation, which disrupts RPL11- and RPL5-MDM2 binding, with Apc min/+ mice, which are prone to intestinal tumor formation. Interestingly, loss of RP-MDM2 binding significantly accelerated colorectal tumor formation while having no discernable effect on small intestinal tumor formation. Mechanistically, APC loss leads to overexpression of c-MYC, RPL11 and RPL5 in mouse colonic tumor cells irrespective of MDM2 C305F mutation. However, notable p53 stabilization and activation were observed only in Apc min/+ ;Mdm2 +/+ but not Apc min/+ ;Mdm2 C305F/C305F colon tumors. These data establish that the RP-MDM2-p53 pathway, in contrast to the p19ARF-MDM2-p53 pathway, is a critical mediator of colorectal tumorigenesis following APC loss.

Wilms tumor gene 1 (WT1), TP53, RAS/BRAF and KIT aberrations in testicular germ cell tumors.

PubMed

Boublikova, L; Bakardjieva-Mihaylova, V; Skvarova Kramarzova, K; Kuzilkova, D; Dobiasova, A; Fiser, K; Stuchly, J; Kotrova, M; Buchler, T; Dusek, P; Grega, M; Rosova, B; Vernerova, Z; Klezl, P; Pesl, M; Zachoval, R; Krolupper, M; Kubecova, M; Stahalova, V; Abrahamova, J; Babjuk, M; Kodet, R; Trka, J

2016-07-01

Wilms tumor gene 1 (WT1), a zinc-finger transcription factor essential for testis development and function, along with other genes, was investigated for their role in the pathogenesis of testicular germ cell tumors (TGCT). In total, 284 TGCT and 100 control samples were investigated, including qPCR for WT1 expression and BRAF mutation, p53 immunohistochemistry detection, and massively parallel amplicon sequencing. WT1 was significantly (p < 0.0001) under-expressed in TGCT, with an increased ratio of exon 5-lacking isoforms, reaching low levels in chemo-naïve relapsed TGCT patients vs. high levels in chemotherapy-pretreated relapsed patients. BRAF V600E mutation was identified in 1% of patients only. p53 protein was lowly expressed in TGCT metastases compared to the matched primary tumors. Of 9 selected TGCT-linked genes, RAS/BRAF and WT1 mutations were frequent while significant TP53 and KIT variants were not detected (p = 0.0003). WT1 has been identified as a novel factor involved in TGCT pathogenesis, with a potential prognostic impact. Distinct biologic nature of the two types of relapses occurring in TGCT has been demonstrated. Differential mutation rate of the key TGCT-related genes has been documented. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

p53 functions as a cell cycle control protein in osteosarcomas.

PubMed

Diller, L; Kassel, J; Nelson, C E; Gryka, M A; Litwak, G; Gebhardt, M; Bressac, B; Ozturk, M; Baker, S J; Vogelstein, B

1990-11-01

Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfected cells to progress into S phase. This suggests that the role of the p53 gene as an antioncogene may be in controlling the cell cycle in a fashion analogous to the check-point control genes in Saccharomyces cerevisiae.

Chaperone-mediated autophagy degrades mutant p53

PubMed Central

Vakifahmetoglu-Norberg, Helin; Kim, Minsu; Xia, Hong-guang; Iwanicki, Marcin P.; Ofengeim, Dimitry; Coloff, Jonathan L.; Pan, Lifeng; Ince, Tan A.; Kroemer, Guido; Brugge, Joan S.; Yuan, Junying

2013-01-01

Missense mutations in the gene TP53, which encodes p53, one of the most important tumor suppressors, are common in human cancers. Accumulated mutant p53 proteins are known to actively contribute to tumor development and metastasis. Thus, promoting the removal of mutant p53 proteins in cancer cells may have therapeutic significance. Here we investigated the mechanisms that govern the turnover of mutant p53 in nonproliferating tumor cells using a combination of pharmacological and genetic approaches. We show that suppression of macroautophagy by multiple means promotes the degradation of mutant p53 through chaperone-mediated autophagy in a lysosome-dependent fashion. In addition, depletion of mutant p53 expression due to macroautophagy inhibition sensitizes the death of dormant cancer cells under nonproliferating conditions. Taken together, our results delineate a novel strategy for killing tumor cells that depend on mutant p53 expression by the activation of chaperone-mediated autophagy and potential pharmacological means to reduce the levels of accumulated mutant p53 without the restriction of mutant p53 conformation in quiescent tumor cells. PMID:23913924

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

Ribosomal protein-Mdm2-p53 pathway coordinates nutrient stress with lipid metabolism by regulating MCD and promoting fatty acid oxidation.

PubMed

Liu, Yong; He, Yizhou; Jin, Aiwen; Tikunov, Andrey P; Zhou, Lishi; Tollini, Laura A; Leslie, Patrick; Kim, Tae-Hyung; Li, Lei O; Coleman, Rosalind A; Gu, Zhennan; Chen, Yong Q; Macdonald, Jeffrey M; Graves, Lee M; Zhang, Yanping

2014-06-10

The tumor suppressor p53 has recently been shown to regulate energy metabolism through multiple mechanisms. However, the in vivo signaling pathways related to p53-mediated metabolic regulation remain largely uncharacterized. By using mice bearing a single amino acid substitution at cysteine residue 305 of mouse double minute 2 (Mdm2(C305F)), which renders Mdm2 deficient in binding ribosomal proteins (RPs) RPL11 and RPL5, we show that the RP-Mdm2-p53 signaling pathway is critical for sensing nutrient deprivation and maintaining liver lipid homeostasis. Although the Mdm2(C305F) mutation does not significantly affect growth and development in mice, this mutation promotes fat accumulation under normal feeding conditions and hepatosteatosis under acute fasting conditions. We show that nutrient deprivation inhibits rRNA biosynthesis, increases RP-Mdm2 interaction, and induces p53-mediated transactivation of malonyl-CoA decarboxylase (MCD), which catalyzes the degradation of malonyl-CoA to acetyl-CoA, thus modulating lipid partitioning. Fasted Mdm2(C305F) mice demonstrate attenuated MCD induction and enhanced malonyl-CoA accumulation in addition to decreased oxidative respiration and increased fatty acid accumulation in the liver. Thus, the RP-Mdm2-p53 pathway appears to function as an endogenous sensor responsible for stimulating fatty acid oxidation in response to nutrient depletion.

Involvements of Estrogen Receptor, Proliferating Cell Nuclear Antigen and p53 in Endometrial Adenocarcinoma Development in Donryu Rats

PubMed Central

Yoshida, Midori; Katsuda, Shin-ichi; Maekawa, Akihiko

2012-01-01

Involvements of estrogen receptor (ER)α, proliferating cell nuclear antigen (PCNA) and p53 in the uterine carcinogenesis process in Donryu rats, a high yield strain of the uterine cancer were investigated immunohistochemically. ERα was expressed in atypical endometrial hyperplasia, accepted as a precancerous lesion of the uterine tumors, as well as well- and in moderately-differentiated endometrial adenocarcinomas, and the intensities of expression were similar to those in the luminal epithelial cells of the atrophic uterus at 15 months of age. The expression, however, was negative in the tumor cells of poorly differentiated type. Good growth of implanted grafts of the poorly-differentiated adenocarcinomas in both sexes with or without gonadectomy supported the estrogen independency of tumor progression to malignancy. PCNA labeling indices were increased with tumor development from atypical hyperplasia to adenocarcinoma. The tumor cells in poorly-differentiated adenocarcinomas were positive for p53 positive but negative for p21 expression, suggesting accumulation of mutated p53. These results indicate that the consistent ERα expression is involved in initiation and promotion steps of uterine carcinogenesis, but not progression. In addition, PCNA is related to tumor development and the expression of mutated p53 might be a late event during endometrial carcinogenesis. PMID:23345926

Distinct Molecular Features of Different Macroscopic Subtypes of Colorectal Neoplasms

PubMed Central

Konda, Kenichi; Konishi, Kazuo; Yamochi, Toshiko; Ito, Yoichi M.; Nozawa, Hisako; Tojo, Masayuki; Shinmura, Kensuke; Kogo, Mari; Katagiri, Atsushi; Kubota, Yutaro; Muramoto, Takashi; Yano, Yuichiro; Kobayashi, Yoshiya; Kihara, Toshihiro; Tagawa, Teppei; Makino, Reiko; Takimoto, Masafumi; Imawari, Michio; Yoshida, Hitoshi

2014-01-01

Background Colorectal adenoma develops into cancer with the accumulation of genetic and epigenetic changes. We studied the underlying molecular and clinicopathological features to better understand the heterogeneity of colorectal neoplasms (CRNs). Methods We evaluated both genetic (mutations of KRAS, BRAF, TP53, and PIK3CA, and microsatellite instability [MSI]) and epigenetic (methylation status of nine genes or sequences, including the CpG island methylator phenotype [CIMP] markers) alterations in 158 CRNs including 56 polypoid neoplasms (PNs), 25 granular type laterally spreading tumors (LST-Gs), 48 non-granular type LSTs (LST-NGs), 19 depressed neoplasms (DNs) and 10 small flat-elevated neoplasms (S-FNs) on the basis of macroscopic appearance. Results S-FNs showed few molecular changes except SFRP1 methylation. Significant differences in the frequency of KRAS mutations were observed among subtypes (68% for LST-Gs, 36% for PNs, 16% for DNs and 6% for LST-NGs) (P<0.001). By contrast, the frequency of TP53 mutation was higher in DNs than PNs or LST-Gs (32% vs. 5% or 0%, respectively) (P<0.007). We also observed significant differences in the frequency of CIMP between LST-Gs and LST-NGs or PNs (32% vs. 6% or 5%, respectively) (P<0.005). Moreover, the methylation level of LINE-1 was significantly lower in DNs or LST-Gs than in PNs (58.3% or 60.5% vs. 63.2%, P<0.05). PIK3CA mutations were detected only in LSTs. Finally, multivariate analyses showed that macroscopic morphologies were significantly associated with an increased risk of molecular changes (PN or LST-G for KRAS mutation, odds ratio [OR] 9.11; LST-NG or DN for TP53 mutation, OR 5.30; LST-G for PIK3CA mutation, OR 26.53; LST-G or DN for LINE-1 hypomethylation, OR 3.41). Conclusion We demonstrated that CRNs could be classified into five macroscopic subtypes according to clinicopathological and molecular differences, suggesting that different mechanisms are involved in the pathogenesis of colorectal tumorigenesis. PMID:25093594

Adenovirally mediated p53 overexpression diversely influence the cell cycle of HEp-2 and CAL 27 cell lines upon cisplatin and methotrexate treatment.

PubMed

Kraljević Pavelić, Sandra; Marjanović, Marko; Poznić, Miroslav; Kralj, Marijeta

2009-12-01

p53 gene plays a crucial role in the response to therapy. Since it is inactivated in the majority of human cancers, it is strongly believed that the p53 mutations confer resistance to therapeutics. In this paper we analyzed the influence of two mechanistically diverse antitumor agents--cisplatin and methotrexate on the proliferation and cell cycle of two head and neck squamous cancer cell lines HEp-2 (wild type p53 gene, but HPV 18/E6-inactivated protein) and CAL 27 (mutated p53 gene), along with the influence of adenovirally mediated p53 overexpression in modulation of cisplatin and methoterexate effects, whereby subtoxic vector/compound concentrations were employed. p53 gene was introduced into tumor cells using adenoviral vector (AdCMV-p53). The cell cycle perturbations were measured by two parameter flow cytometry. The expression of p53, p21(WAF1/CIP1) and cyclin B1 proteins was examined using immunocytochemistry and western blot methods. In CAL 27 cells overexpression of p53 completely abrogated high S phase content observed in methotrexate-treated cells into a G1 and slight G2 arrest, while it sustained G2 arrest of the cells treated with cisplatin, along with the reduction of DNA synthesis and cyclin B1 expression. On the other hand, in HEp-2 cell line p53 overexpression slightly slowed down the progression through S phase in cells treated with methotrexate, decreased the cyclin B1 expression only after 24 h, and failed to sustain the G2 arrest after treatment with cisplatin alone. Instead, it increased the population of S phase cells that were not actively synthesizing DNA, sustained cyclin B1 expression and allowed the G2 cells to progress through mitosis. This study demonstrates that adenovirally mediated p53 overexpression at sub-cytotoxic levels enhanced the activity of low doses of cisplatin and methotrexate in HEp-2 and CAL 27 cells through changes in the cell cycle. However, the mechanisms of these effects differ depending on the genetic context and on the chemotherapeutics' modality of action.

TP53 mutation and human papilloma virus status of oral squamous cell carcinomas in young adult patients.

PubMed

Braakhuis, B J M; Rietbergen, M M; Buijze, M; Snijders, P J F; Bloemena, E; Brakenhoff, R H; Leemans, C R

2014-09-01

Little is known about the molecular carcinogenesis of oral squamous cell carcinoma (OSCC) in young adult patients. The aim of this study was to investigate the detailed TP53 mutation and human papilloma virus (HPV) status of OSCC in patients, younger than 45 years. TP53 mutations were determined with direct sequencing on paraffin-embedded carcinoma tissue from 31 young patients and compared with two older age OSCC reference groups: one from the same institute (N = 87) and an independent one (N = 675). Biologically active tumour HPV was detected by p16-immunohistochemistry followed by a HPV-DNA GP5 + /6 + -PCR. HPV16 was present in one OSCC (3%). TP53 mutations were found in 14 (45%) OSCC: five were missense and nine resulted in a truncated protein. Six of these latter were insertions or deletions of one or more nucleotides leading to frameshift, one was at a splice site and two resulted in a stop codon. The percentage of truncating mutations (64% of all mutations) was higher than that observed in the institute's reference group (44%, P = 0.23) and in the independent reference group (24%, P = 0.002). This study shows that TP53 mutations are common in OSCC of young adult patients; infection with biologically active HPV is rare. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Genetic and epigenetic mutations of tumor suppressive genes in sporadic pituitary adenoma

PubMed Central

Zhou, Yunli; Zhang, Xun; Klibanski, Anne

2013-01-01

Human pituitary adenomas are the most common intracranial neoplasms. Approximately 5% of them are familial adenomas. Patients with familial tumors carry germline mutations in predisposition genes, including AIP, MEN1 and PRKAR1A. These mutations are extremely rare in sporadic pituitary adenomas, which therefore are caused by different mechanisms. Multiple tumor suppressive genes linked to sporadic tumors have been identified. Their inactivation is caused by epigenetic mechanisms, mainly promoter hypermethylation, and can be placed into two groups based on their functional interaction with tumor suppressors RB or p53. The RB group includes CDKN2A, CDKN2B, CDKN2C, RB1, BMP4, CDH1, CDH13, GADD45B and GADD45G; AIP and MEN1 genes also belong to this group. The p53 group includes MEG3, MGMT, PLAGL1, RASSF1, RASSF3 and SOCS1. We propose that the tumor suppression function of these genes is mainly mediated by the RB and p53 pathways. We also discuss possible tumor suppression mechanisms for individual genes. PMID:24035864

Impact of the number of mutations in survival and response outcomes to hypomethylating agents in patients with myelodysplastic syndromes or myelodysplastic/myeloproliferative neoplasms

PubMed Central

Montalban-Bravo, Guillermo; Takahashi, Koichi; Patel, Keyur; Wang, Feng; Xingzhi, Song; Nogueras, Graciela M.; Huang, Xuelin; Pierola, Ana Alfonso; Jabbour, Elias; Colla, Simona; Gañan-Gomez, Irene; Borthakur, Gautham; Daver, Naval; Estrov, Zeev; Kadia, Tapan; Pemmaraju, Naveen; Ravandi, Farhad; Bueso-Ramos, Carlos; Chamseddine, Ali; Konopleva, Marina; Zhang, Jianhua; Kantarjian, Hagop; Futreal, Andrew; Garcia-Manero, Guillermo

2018-01-01

The prognostic and predictive value of sequencing analysis in myelodysplastic syndromes (MDS) has not been fully integrated into clinical practice. We performed whole exome sequencing (WES) of bone marrow samples from 83 patients with MDS and 31 with MDS/MPN identifying 218 driver mutations in 31 genes in 98 (86%) patients. A total of 65 (57%) patients received therapy with hypomethylating agents. By univariate analysis, mutations in BCOR, STAG2, TP53 and SF3B1 significantly influenced survival. Increased number of mutations (≥ 3), but not clonal heterogeneity, predicted for shorter survival and LFS. Presence of 3 or more mutations also predicted for lower likelihood of response (26 vs 50%, p = 0.055), and shorter response duration (3.6 vs 26.5 months, p = 0.022). By multivariate analysis, TP53 mutations (HR 3.1, CI 1.3–7.5, p = 0.011) and number of mutations (≥ 3) (HR 2.5, CI 1.3–4.8, p = 0.005) predicted for shorter survival. A novel prognostic model integrating this mutation data with IPSS-R separated patients into three categories with median survival of not reached, 29 months and 12 months respectively (p < 0.001) and increased stratification potential, compared to IPSS-R, in patients with high/very-high IPSS-R. This model was validated in a separate cohort of 413 patients with untreated MDS. Although the use of WES did not provide significant more information than that obtained with targeted sequencing, our findings indicate that increased number of mutations is an independent prognostic factor in MDS and that mutation data can add value to clinical prognostic models. PMID:29515765

Impact of the number of mutations in survival and response outcomes to hypomethylating agents in patients with myelodysplastic syndromes or myelodysplastic/myeloproliferative neoplasms.

PubMed

Montalban-Bravo, Guillermo; Takahashi, Koichi; Patel, Keyur; Wang, Feng; Xingzhi, Song; Nogueras, Graciela M; Huang, Xuelin; Pierola, Ana Alfonso; Jabbour, Elias; Colla, Simona; Gañan-Gomez, Irene; Borthakur, Gautham; Daver, Naval; Estrov, Zeev; Kadia, Tapan; Pemmaraju, Naveen; Ravandi, Farhad; Bueso-Ramos, Carlos; Chamseddine, Ali; Konopleva, Marina; Zhang, Jianhua; Kantarjian, Hagop; Futreal, Andrew; Garcia-Manero, Guillermo

2018-02-09

The prognostic and predictive value of sequencing analysis in myelodysplastic syndromes (MDS) has not been fully integrated into clinical practice. We performed whole exome sequencing (WES) of bone marrow samples from 83 patients with MDS and 31 with MDS/MPN identifying 218 driver mutations in 31 genes in 98 (86%) patients. A total of 65 (57%) patients received therapy with hypomethylating agents. By univariate analysis, mutations in BCOR, STAG2, TP53 and SF3B1 significantly influenced survival. Increased number of mutations (≥ 3), but not clonal heterogeneity, predicted for shorter survival and LFS. Presence of 3 or more mutations also predicted for lower likelihood of response (26 vs 50%, p = 0.055), and shorter response duration (3.6 vs 26.5 months, p = 0.022). By multivariate analysis, TP53 mutations (HR 3.1, CI 1.3-7.5, p = 0.011) and number of mutations (≥ 3) (HR 2.5, CI 1.3-4.8, p = 0.005) predicted for shorter survival. A novel prognostic model integrating this mutation data with IPSS-R separated patients into three categories with median survival of not reached, 29 months and 12 months respectively ( p < 0.001) and increased stratification potential, compared to IPSS-R, in patients with high/very-high IPSS-R. This model was validated in a separate cohort of 413 patients with untreated MDS. Although the use of WES did not provide significant more information than that obtained with targeted sequencing, our findings indicate that increased number of mutations is an independent prognostic factor in MDS and that mutation data can add value to clinical prognostic models.

p21WAF1 immunohistochemical expression in breast carcinoma: correlations with clinicopathological data, oestrogen receptor status, MIB1 expression, p53 gene and protein alterations and relapse-free survival.

PubMed Central

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

1996-01-01

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

Interactions between the otitis media gene, Fbxo11, and p53 in the mouse embryonic lung.

PubMed

Tateossian, Hilda; Morse, Susan; Simon, Michelle M; Dean, Charlotte H; Brown, Steve D M

2015-12-01

Otitis media with effusion (OME) is the most common cause of hearing loss in children, and tympanostomy (ear tube insertion) to alleviate the condition remains the commonest surgical intervention in children in the developed world. Chronic and recurrent forms of otitis media (OM) are known to have a very substantial genetic component; however, until recently, little was known of the underlying genes involved. The Jeff mouse mutant carries a mutation in the Fbxo11 gene, a member of the F-box family, and develops deafness due to a chronic proliferative OM. We previously reported that Fbxo11 is involved in the regulation of transforming growth factor beta (TGF-β) signalling by regulating the levels of phospho-Smad2 in the epithelial cells of palatal shelves, eyelids and airways of the lungs. It has been proposed that FBXO11 regulates the cell's response to TGF-β through the ubiquitination of CDT2. Additional substrates for FBXO11 have been identified, including p53. Here, we have studied both the genetic and biochemical interactions between FBXO11 and p53 in order to better understand the function of FBXO11 in epithelial development and its potential role in OM. In mice, we show that p53 (also known as Tp53) homozygous mutants and double heterozygous mutants (Jf/+ p53/+) exhibit similar epithelial developmental defects to Fbxo11 homozygotes. FBXO11 and p53 interact in the embryonic lung, and mutation in Fbxo11 prevents the interaction with p53. Both p53 and double mutants show raised levels of pSMAD2, recapitulating that seen in Fbxo11 homozygotes. Overall, our results support the conclusion that FBXO11 regulates the TGF-β pathway in the embryonic lung via cross-talk with p53. © 2015. Published by The Company of Biologists Ltd.

Shared genetic predisposition in rheumatoid arthritis-interstitial lung disease and familial pulmonary fibrosis.

PubMed

Juge, Pierre-Antoine; Borie, Raphaël; Kannengiesser, Caroline; Gazal, Steven; Revy, Patrick; Wemeau-Stervinou, Lidwine; Debray, Marie-Pierre; Ottaviani, Sébastien; Marchand-Adam, Sylvain; Nathan, Nadia; Thabut, Gabriel; Richez, Christophe; Nunes, Hilario; Callebaut, Isabelle; Justet, Aurélien; Leulliot, Nicolas; Bonnefond, Amélie; Salgado, David; Richette, Pascal; Desvignes, Jean-Pierre; Lioté, Huguette; Froguel, Philippe; Allanore, Yannick; Sand, Olivier; Dromer, Claire; Flipo, René-Marc; Clément, Annick; Béroud, Christophe; Sibilia, Jean; Coustet, Baptiste; Cottin, Vincent; Boissier, Marie-Christophe; Wallaert, Benoit; Schaeverbeke, Thierry; Dastot le Moal, Florence; Frazier, Aline; Ménard, Christelle; Soubrier, Martin; Saidenberg, Nathalie; Valeyre, Dominique; Amselem, Serge; Boileau, Catherine; Crestani, Bruno; Dieudé, Philippe

2017-05-01

Despite its high prevalence and mortality, little is known about the pathogenesis of rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Given that familial pulmonary fibrosis (FPF) and RA-ILD frequently share the usual pattern of interstitial pneumonia and common environmental risk factors, we hypothesised that the two diseases might share additional risk factors, including FPF-linked genes. Our aim was to identify coding mutations of FPF-risk genes associated with RA-ILD.We used whole exome sequencing (WES), followed by restricted analysis of a discrete number of FPF-linked genes and performed a burden test to assess the excess number of mutations in RA-ILD patients compared to controls.Among the 101 RA-ILD patients included, 12 (11.9%) had 13 WES-identified heterozygous mutations in the TERT , RTEL1 , PARN or SFTPC coding regions . The burden test, based on 81 RA-ILD patients and 1010 controls of European ancestry, revealed an excess of TERT , RTEL1 , PARN or SFTPC mutations in RA-ILD patients (OR 3.17, 95% CI 1.53-6.12; p=9.45×10 -4 ). Telomeres were shorter in RA-ILD patients with a TERT , RTEL1 or PARN mutation than in controls (p=2.87×10 -2 ).Our results support the contribution of FPF-linked genes to RA-ILD susceptibility. Copyright ©ERS 2017.

Hypoxic resistance of KRAS mutant tumor cells to 3-Bromopyruvate is counteracted by Prima-1 and reversed by N-acetylcysteine.

PubMed

Orue, Andrea; Chavez, Valery; Strasberg-Rieber, Mary; Rieber, Manuel

2016-11-18

The metabolic inhibitor 3-bromopyruvate (3-BrPA) is a promising anti-cancer alkylating agent, shown to inhibit growth of some colorectal carcinoma with KRAS mutation. Recently, we demonstrated increased resistance to 3-BrPA in wt p53 tumor cells compared to those with p53 silencing or mutation. Since hypoxic microenvironments select for tumor cells with diminished therapeutic response, we investigated whether hypoxia unequally increases resistance to 3-BrPA in wt p53 MelJuso melanoma harbouring (Q61L)-mutant NRAS and wt BRAF, C8161 melanoma with (G12D)-mutant KRAS (G464E)-mutant BRAF, and A549 lung carcinoma with a KRAS (G12S)-mutation. Since hypoxia increases the toxicity of the p53 activator, Prima-1 against breast cancer cells irrespective of their p53 status, we also investigated whether Prima-1 reversed hypoxic resistance to 3-BrPA. In contrast to the high susceptibility of hypoxic mutant NRAS MelJuso cells to 3-BrPA or Prima-1, KRAS mutant C8161 and A549 cells revealed hypoxic resistance to 3-BrPA counteracted by Prima-1. In A549 cells, Prima-1 increased p21CDKN1mRNA, and reciprocally inhibited mRNA expression of the SLC2A1-GLUT1 glucose transporter-1 and ALDH1A1, gene linked to detoxification and stem cell properties. 3-BrPA lowered CAIX and VEGF mRNA expression. Death from joint Prima-1 and 3-BrPA treatment in KRAS mutant A549 and C8161 cells seemed mediated by potentiating oxidative stress, since it was antagonized by the anti-oxidant and glutathione precursor N-acetylcysteine. This report is the first to show that Prima-1 kills hypoxic wt p53 KRAS-mutant cells resistant to 3-BrPA, partly by decreasing GLUT-1 expression and exacerbating pro-oxidant stress.

Identification of a Novel Mutation in BRD4 that Causes Autosomal Dominant Syndromic Congenital Cataracts Associated with Other Neuro-Skeletal Anomalies

PubMed Central

Jin, Hyun-Seok; Kim, Jeonhyun; Kwak, Woori; Jeong, Hyeonsoo; Lim, Gyu-Bin

2017-01-01

Congenital cataracts can occur as a non-syndromic isolated ocular disease or as a part of genetic syndromes accompanied by a multi-systemic disease. Approximately 50% of all congenital cataract cases have a heterogeneous genetic basis. Here, we describe three generations of a family with an autosomal dominant inheritance pattern and common complex phenotypes, including bilateral congenital cataracts, short stature, macrocephaly, and minor skeletal anomalies. We did not find any chromosomal aberrations or gene copy number abnormalities using conventional genetic tests; accordingly, we conducted whole-exome sequencing (WES) to identify disease-causing genetic alterations in this family. Based on family WES data, we identified a novel BRD4 missense mutation as a candidate causal variant and performed cell-based experiments by ablation of endogenous BRD4 expression in human lens epithelial cells. The protein expression levels of connexin 43, p62, LC3BII, and p53 differed significantly between control cells and cells in which endogenous BRD4 expression was inhibited. We inferred that a BRD4 missense mutation was the likely disease-causing mutation in this family. Our findings may improve the molecular diagnosis of congenital cataracts and support the use of WES to clarify the genetic basis of complex diseases. PMID:28076398

The curcumin analog HO-3867 selectively kills cancer cells by converting mutant p53 protein to transcriptionally active wildtype p53.

PubMed

Madan, Esha; Parker, Taylor M; Bauer, Matthias R; Dhiman, Alisha; Pelham, Christopher J; Nagane, Masaki; Kuppusamy, M Lakshmi; Holmes, Matti; Holmes, Thomas R; Shaik, Kranti; Shee, Kevin; Kiparoidze, Salome; Smith, Sean D; Park, Yu-Soon A; Gomm, Jennifer J; Jones, Louise J; Tomás, Ana R; Cunha, Ana C; Selvendiran, Karuppaiyah; Hansen, Laura A; Fersht, Alan R; Hideg, Kálmán; Gogna, Rajan; Kuppusamy, Periannan

2018-03-23

p53 is an important tumor-suppressor protein that is mutated in more than 50% of cancers. Strategies for restoring normal p53 function are complicated by the oncogenic properties of mutant p53 and have not met with clinical success. To counteract mutant p53 activity, a variety of drugs with the potential to reconvert mutant p53 to an active wildtype form have been developed. However, these drugs are associated with various negative effects such as cellular toxicity, nonspecific binding to other proteins, and inability to induce a wildtype p53 response in cancer tissue. Here, we report on the effects of a curcumin analog, HO-3867, on p53 activity in cancer cells from different origins. We found that HO-3867 covalently binds to mutant p53, initiates a wildtype p53-like anticancer genetic response, is exclusively cytotoxic toward cancer cells, and exhibits high anticancer efficacy in tumor models. In conclusion, HO-3867 is a p53 mutant-reactivating drug with high clinical anticancer potential. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Plac8 links oncogenic mutations to regulation of autophagy and is critical to pancreatic cancer progression

PubMed Central

Kinsey, Conan; Balakrishnan, Vijaya; O’Dell, Michael R.; Huang, Jing Li; Newman, Laurel; Whitney-Miller, Christa L.; Hezel, Aram F.; Land, Hartmut

2014-01-01

Summary Mutations in p53 and RAS potently cooperate in oncogenic transformation and correspondingly these genetic alterations frequently coexist in pancreatic ductal adenocarcinoma (PDA) and other human cancers. Previously we identified a set of genes synergistically activated by combined RAS and p53 mutations as frequent downstream mediators of tumorigenesis. Here, we show that the synergistically activated gene Plac8 is critical for pancreatic cancer growth. Silencing of Plac8 in cell lines suppresses tumor formation by blocking autophagy, a process essential for maintaining metabolic homeostasis in PDA, and genetic inactivation in an engineered mouse model inhibits PDA progression. We show that Plac8 is a critical regulator of the autophagic machinery, localizing to the lysosomal compartment and facilitating lysosome-autophagosome fusion. Plac8 thus provides a mechanistic link between primary oncogenic mutations and the induction of autophagy, a central mechanism of metabolic reprogramming, during PDA progression. PMID:24794439

Novel Insight into Mutational Landscape of Head and Neck Squamous Cell Carcinoma

PubMed Central

Gaykalova, Daria A.; Mambo, Elizabeth; Choudhary, Ashish; Houghton, Jeffery; Buddavarapu, Kalyan; Sanford, Tiffany; Darden, Will; Adai, Alex; Hadd, Andrew; Latham, Gary; Danilova, Ludmila V.; Bishop, Justin; Li, Ryan J.; Westra, William H.; Hennessey, Patrick; Koch, Wayne M.; Ochs, Michael F.; Califano, Joseph A.; Sun, Wenyue

2014-01-01

Development of head and neck squamous cell carcinoma (HNSCC) is characterized by accumulation of mutations in several oncogenes and tumor suppressor genes. We have formerly described the mutation pattern of HNSCC and described NOTCH signaling pathway alterations. Given the complexity of the HNSCC, here we extend the previous study to understand the overall HNSCC mutation context and to discover additional genetic alterations. We performed high depth targeted exon sequencing of 51 highly actionable cancer-related genes with a high frequency of mutation across many cancer types, including head and neck. DNA from primary tumor tissues and matched normal tissues was analyzed for 37 HNSCC patients. We identified 26 non-synonymous or stop-gained mutations targeting 11 of 51 selected genes. These genes were mutated in 17 out of 37 (46%) studied HNSCC patients. Smokers harbored 3.2-fold more mutations than non-smokers. Importantly, TP53 was mutated in 30%, NOTCH1 in 8% and FGFR3 in 5% of HNSCC. HPV negative patients harbored 4-fold more TP53 mutations than HPV positive patients. These data confirm prior reports of the HNSCC mutational profile. Additionally, we detected mutations in two new genes, CEBPA and FES, which have not been previously reported in HNSCC. These data extend the spectrum of HNSCC mutations and define novel mutation targets in HNSCC carcinogenesis, especially for smokers and HNSCC without HPV infection. PMID:24667986

Treacher Collins Syndrome: the genetics of a craniofacial disease.

PubMed

Kadakia, Sameep; Helman, Samuel N; Badhey, Arvind K; Saman, Masoud; Ducic, Yadranko

2014-06-01

The molecular underpinnings of Treacher Collins Syndrome (TCS) are diverse. This article codifies the most recent findings in this complex area of research to further current understanding of the disease process. Elucidating the genetic causes of the disorder can be useful in earlier detection and better treatment planning. Articles from 1991 to 2013 were selected and reviewed by five researchers utilizing the most recent literature of the genetics and pathophysiology of TCS. Mutations in TCOF1, POLR1C and POLR1D have all been implicated in causing TCS. The association of the TCOF1 gene product, Treacle, and gene products of POLR1C and POLR1D with ribosome biosynthesis suggests that a loss of function mutation in these genes disrupts ribosome biosynthesis in constituent neural crest cells and neuroepithelium leading to apoptosis. However, recent data illustrating that P53 heterozygosity is protective against TCS, and that P53 and TCOF1 hemizygous embryos do not affect ribosomal function, implicates P53 or elements downstream of P53 as playing a role in TCS pathogenesis. Our study codified nascent findings of the molecular determinants of TCS. These findings add to a burgeoning database of TCS-associated mutations, and as such, can be used to establish TCS diagnosis and further clarify TCS pathogenesis. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Next-Generation Sequencing of a Cohort of Pulmonary Large Cell Carcinomas Reclassified by World Health Organization 2015 Criteria.

PubMed

Driver, Brandon R; Portier, Bryce P; Mody, Dina R; Deavers, Michael; Bernicker, Eric H; Kim, Min P; Teh, Bin S; Santacruz, Jose F; Kopas, Lisa; Munden, Reginald F; Cagle, Philip T

2016-04-01

The classification of pulmonary large cell carcinoma has undergone a major revision with the recent World Health Organization (WHO) 2015 Classification. Many large cell carcinomas are now reassigned to either adenocarcinoma with solid pattern or nonkeratinizing squamous cell carcinoma based on immunopositivity for adenocarcinoma markers or squamous cell carcinoma markers, respectively. Large cell carcinomas that are negative for adenocarcinoma and squamous cell carcinoma immunomarkers are now classified as large cell carcinoma with null immunohistochemical features (LCC-N). Although a few studies investigated the mutation profile of large cell carcinomas grouped by immunostain profile before the publication of the new WHO classification, investigation of tumors previously diagnosed as large cell carcinoma and reclassified according to the 2015 WHO classification has not, to our knowledge, been reported. To determine the mutation profiles of pulmonary large cell carcinomas reclassified by WHO 2015 criteria. Archival cases of non-small cell lung carcinoma with large cell carcinoma morphology (n = 17) were reclassified according to 2015 WHO criteria. To determine mutation profile, we employed Ion Torrent (Life Technologies, Carlsbad, California)-based next-generation sequencing (50 genes; more than 2800 mutations) in addition to real-time quantitative reverse transcription polymerase chain reaction for ALK translocation detection. Two of 17 cases (12%) were reclassified as LCC-N, and both had mutations-BRAF D594N in one case and KRAS G12C in the other case. Seven of 17 cases (41%) were reclassified in the adenocarcinoma with solid pattern group, which showed one KRAS G12C and one EGFR E709K + G719C double mutation in addition to mutations in TP53. Eight of 17 cases (47%) were reclassified in the nonkeratinizing squamous cell carcinoma group, which showed mutations in PIK3CA, CDKN2A, and TP53. No ALK translocations or amplifications were detected. The adenocarcinoma with solid pattern group showed mutations typical of adenocarcinoma, whereas the nonkeratinizing squamous cell carcinoma group showed mutations typical of squamous cell carcinoma. Both LCC-N cases had mutations associated with adenocarcinoma, supporting the hypothesis that LCC-N is related to adenocarcinoma.

The role of LKB1 in lung cancer.

PubMed

Sanchez-Cespedes, Montse

2011-09-01

In humans, the LKB1 gene is located on the short arm of chromosome 19, which is frequently deleted in lung tumors. Unlike most cancers of sporadic origin, in non-small cell lung cancer (NSCLC) nearly half of the tumors harbor somatic and homozygous inactivating mutations in LKB1. In NSCLC, LKB1 inactivation strongly predominates in adenocarcinomas from smokers and coexists with mutations at other important cancer genes, including KRAS and TP53. Remarkably, LKB1 alterations frequently occur simultaneously with inactivation at another important tumor suppressor gene, BRG1 (also called SMARCA4), which is also located on chromosome 19p. The present review considers the frequency and pattern of LKB1 mutations in lung cancer and the distinct biological pathways in which the LKB1 protein is involved in the development of this type of cancer. Finally, the possible clinical applications in cancer management, especially in lung cancer treatment, associated with the presence of absence of LKB1 are discussed.

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

PubMed

Wachter, Franziska; Grunert, Michaela; Blaj, Cristina; Weinstock, David M; Jeremias, Irmela; Ehrhardt, Harald

2013-04-17

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. 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. 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.

Colorectal tumor molecular phenotype and miRNA: expression profiles and prognosis.

PubMed

Slattery, Martha L; Herrick, Jennifer S; Mullany, Lila E; Wolff, Erica; Hoffman, Michael D; Pellatt, Daniel F; Stevens, John R; Wolff, Roger K

2016-08-01

MiRNAs regulate gene expression by post-transcriptionally suppressing mRNA translation or by causing mRNA degradation. It has been proposed that unique miRNAs influence specific tumor molecular phenotype. In this paper, we test the hypotheses that miRNA expression differs by tumor molecular phenotype and that those differences may influence prognosis. Data come from population-based studies of colorectal cancer conducted in Utah and the Northern California Kaiser Permanente Medical Care Program. A total of 1893 carcinoma samples were run on the Agilent Human miRNA Microarray V19.0 containing 2006 miRNAs. We assessed differences in miRNA expression between TP53-mutated and non-mutated, KRAS-mutated and non-mutated, BRAF-mutated and non-mutated, CpG island methylator phenotype (CIMP) high and CIMP low, and microsatellite instability (MSI) and microsatellite stable (MSS) colon and rectal tumors. Using a Cox proportional hazard model we evaluated if those miRNAs differentially expressed by tumor phenotype influenced survival after adjusting for age, sex, and AJCC stage. There were 22 differentially expressed miRNAs for TP53-mutated colon tumors and 5 for TP53-mutated rectal tumors with a fold change of >1.49 (or <0.67). Additionally, 13 miRNAS were differentially expressed for KRAS-mutated rectal tumors, 8 differentially expressed miRNAs for colon CIMP high tumors, and 2 differentially expressed miRNAs for BRAF-mutated colon tumors. The majority of differentially expressed miRNAS were observed between MSI and MSS tumors (94 differentially expressed miRNAs for colon; 41 differentially expressed miRNAs for rectal tumors). Of these miRNAs differentially expressed between MSI and MSS tumors, the majority were downregulated. Ten of the differentially expressed miRNAs were associated with survival; after adjustment for MSI status, five miRNAS, miR-196b-5p, miR-31-5p, miR-99b-5p, miR-636, and miR-192-3p, were significantly associated with survival. In summary, it appears that the majority of miRNAs that are differentially expressed by tumor molecular phenotype are MSI tumors. However, these miRNAs appear to have minimal effect on prognosis.

Mixed and Ambiguous Endometrial Carcinomas: A Heterogenous Group of Tumors With Different Clinicopathologic and Molecular Genetic Features.

PubMed

Espinosa, Iñigo; D'Angelo, Emanuela; Palacios, José; Prat, Jaime

2016-07-01

Besides endometrioid, serous, and clear cell carcinomas, there are endometrial carcinomas exhibiting mixed and ambiguous morphologic features. We have analyzed the immunophenotype (p53, p16, β-catenin, ER, HNF-1B, MLH1, and Ki-67) and mutational status (PTEN, KRAS, PIK3CA, and POLE) of 7 mixed carcinomas and 13 ambiguous carcinomas, all of them classified initially as mixed carcinomas. Only 2 of the 7 (28%) mixed carcinomas showed different immunophenotypes in different components. All but 2 tumors (5/7, 71%) overexpressed p53 and p16 and were negative for ER. Both carcinomas (2/7, 28%) showed a prominent micropapillary component that resembled an ovarian low-grade serous carcinoma and merged with villoglandular endometrioid carcinoma. The ambiguous carcinomas exhibited glandular architecture, high nuclear grade, and overlapping features of endometrioid and serous carcinomas. All tumors overexpressed p53 and p16, and the majority of cases (12/13, 92%) were negative for ER. KRAS mutations were identified in 3 of 7 (42%) mixed carcinomas, including the 2 cases with a "low-grade" serous-like component. PIK3CA mutations occurred in 2 (2/13, 15%) ambiguous carcinomas and PTEN mutations in 1 (1/7, 14%) mixed and 1 (1/13, 8%) ambiguous carcinoma. POLE exonuclease domain mutations were encountered in a case of mixed undifferentiated and well-differentiated (dedifferentiated) carcinoma. Two of the 7 (29%) mixed endometrial carcinomas and 5 of the 13 (38%) ambiguous carcinomas had extended beyond the pelvis (stages III and IV). Two of the 7 (29%) patients with mixed endometrial carcinoma and 6 of 12 (50%) patients with ambiguous endometrial carcinoma were alive with disease or had died of tumor. Our results show that, biologically, many so-called mixed carcinomas represent serous carcinomas with ambiguous morphology. Our series include 2 true mixed endometrial carcinomas with a "low-grade serous"-like component, microcystic, elongated, or fragmented features, KRAS mutations, and aggressive behavior.

P53 Gene Mutagenesis in Breast Cancer

DTIC Science & Technology

2005-03-01

the wild type T peak. 12 Table 1. Sonic ntations dected by SINtA Individual Cell Sequence Amino Acid Species Conservation 3 ID’ ID Change2 Change... differences in the content of toxic substances in the diet (Biggs et al., 1993; Blaszyk et al., 1996). The development of this p53 mutation load...Changes in the P53 Gene in Single Cells Individual Sequence Amino acid Species conservation ’ ID’ Cell ID change’ change Monkey Mouse Rat Chicken

Oxidation of p53 through DNA Charge Transport Involves a Network of Disulfides within the DNA-Binding Domain

PubMed Central

2016-01-01

Transcription factor p53 plays a critical role in the cellular response to stress stimuli. We have seen that p53 dissociates selectively from various promoter sites as a result of oxidation at long-range through DNA-mediated charge transport (CT). Here, we examine this chemical oxidation and determine the residues in p53 that are essential for oxidative dissociation, focusing on the network of cysteine residues adjacent to the DNA-binding site. Of the eight mutants studied, only the C275S mutation shows decreased affinity for the Gadd45 promoter site. However, both mutations C275S and C277S result in substantial attenuation of oxidative dissociation, with C275S causing the most severe attenuation. Differential thiol labeling was used to determine the oxidation states of cysteine residues within p53 after DNA-mediated oxidation. Reduced cysteines were iodoacetamide-labeled, whereas oxidized cysteines participating in disulfide bonds were 13C2D2-iodoacetamide-labeled. Intensities of respective iodoacetamide-modified peptide fragments were analyzed by mass spectrometry. A distinct shift in peptide labeling toward 13C2D2-iodoacetamide-labeled cysteines is observed in oxidized samples, confirming that chemical oxidation of p53 occurs at long range. All observable cysteine residues trend toward the heavy label under conditions of DNA CT, indicating the formation of multiple disulfide bonds among the cysteine network. On the basis of these data, it is proposed that disulfide formation involving C275 is critical for inducing oxidative dissociation of p53 from DNA. PMID:25584637

p53 functions as a cell cycle control protein in osteosarcomas.

PubMed Central

Diller, L; Kassel, J; Nelson, C E; Gryka, M A; Litwak, G; Gebhardt, M; Bressac, B; Ozturk, M; Baker, S J; Vogelstein, B

1990-01-01

Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfected cells to progress into S phase. This suggests that the role of the p53 gene as an antioncogene may be in controlling the cell cycle in a fashion analogous to the check-point control genes in Saccharomyces cerevisiae. Images PMID:2233717

P-Glycoprotein/MDR1 regulates pokemon gene transcription through p53 expression in human breast cancer cells.

PubMed

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

2010-08-27

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

P-Glycoprotein/MDR1 Regulates Pokemon Gene Transcription Through p53 Expression in Human Breast Cancer Cells

PubMed Central

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

2010-01-01

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

GE-17ALTERATION OF THE p53 PATHWAY AND ANCESTRAL PROGENITORS ARE ASSOCIATED WITH TUMOR RECURRENCE IN GLIOBLASTOMA

PubMed Central

Kim, Hoon; Zheng, Siyuan; Amini, Seyed; Virk, Selene; Mikkelsen, Tom; Brat, Daniel; Sougnez, Carrie; Muller, Florian; Hu, Jian; Sloan, Andrew; Cohen, Mark; Van Meir, Erwin; Scarpace, Lisa; Lander, Eric; Gabriel, Stacey; Getz, Gad; Meyerson, Matthew; Chin, Lynda; Barnholtz-Sloan, Jill; Verhaak, Roel

2014-01-01

To evaluate evolutionary patterns of GBM recurrence, we analyzed whole genome sequencing (WGS) and multi-sector exome sequencing data from pairs of primary and posttreatment GBM. WGS on ten primary-recurrent pairs detected a median number of 12,214 mutations which we utilized to uncover clonal structures, by analyzing the distribution of mutation cellular frequencies (the fraction of tumor cells harboring a mutation). On average, 41 % of the mutations were shared by primary and recurrence. The majority of shared mutations were clonal in both primary and recurrence, but we also observed many clonal mutations that were uniquely detected in either the primary or the recurrence. This raises the intriguing possibility that major tumor clones in the primary tumor and disease relapse both evolved from a shared ancestral tumor cell population. At least one subclone was identified in the majority of WGS samples, and we observed groups of mutations that were at low cancer cell fractions in both primary and recurrence, suggesting that both subclones evolved from the same ancestral tumor cells separate from the major clone ancestral cells. To address the possibility that the lack of overlap between subsequent tumors was due to intratumoral heterogeneity, we analyzed exome sequencing from a second tumor sector of seven primary and six recurrent tumors. We found that the majority of "second biopsy" mutations were not conserved between time points, suggesting that intratumoral heterogeneity did not explain the large number of mutations uniquely detected in primary and recurrence. The limited overlap of mutations in primary and recurrence provides evidence for ancestral tumor cell populations that could not be eradicated by therapy, while offspring cell populations contained unique mutations, were selectively killed by treatment and could therefore no longer be detected after disease relapse. This study has provided new insights into patterns and dynamics of tumor evolution.

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.

Expressions of p53 and p21 in primary gastric lymphomas.

PubMed Central

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

2001-01-01

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

Robustness of the p53 network and biological hackers.

PubMed

Dartnell, Lewis; Simeonidis, Evangelos; Hubank, Michael; Tsoka, Sophia; Bogle, I David L; Papageorgiou, Lazaros G

2005-06-06

The p53 protein interaction network is crucial in regulating the metazoan cell cycle and apoptosis. Here, the robustness of the p53 network is studied by analyzing its degeneration under two modes of attack. Linear Programming is used to calculate average path lengths among proteins and the network diameter as measures of functionality. The p53 network is found to be robust to random loss of nodes, but vulnerable to a targeted attack against its hubs, as a result of its architecture. The significance of the results is considered with respect to mutational knockouts of proteins and the directed attacks mounted by tumour inducing viruses.

HPV-18 E6 mutants reveal p53 modulation of viral DNA amplification in organotypic cultures

PubMed Central

Kho, Eun-Young; Wang, Hsu-Kun; Banerjee, N. Sanjib; Broker, Thomas R.; Chow, Louise T.

2013-01-01

Human papillomaviruses (HPVs) amplify in differentiated strata of a squamous epithelium. The HPV E7 protein destabilizes the p130/retinoblastoma susceptibility protein family of tumor suppressors and reactivates S-phase reentry, thereby facilitating viral DNA amplification. The high-risk HPV E6 protein destabilizes the p53 tumor suppressor and many other host proteins. However, the critical E6 targets relevant to viral DNA amplification have not been identified, because functionally significant E6 mutants are not stably maintained in transfected cells. Using Cre-loxP recombination, which efficiently generates HPV genomic plasmids in transfected primary human keratinocytes, we have recapitulated a highly productive infection of HPV-18 in organotypic epithelial cultures. By using this system, we now report the characterization of four HPV-18 E6 mutations. An E6 null mutant accumulated high levels of p53 and amplified very poorly. p53 siRNA or ectopic WT E6 partially restored amplification, whereas three missense E6 mutations that did not effectively destabilize p53 complemented the null mutant poorly. Unexpectedly, in cis, two of the missense mutants amplified, albeit to a lower extent than the WT and only in cells with undetectable p53. These observations and others implicate p53 and additional host proteins in regulating viral DNA amplification and also suggest an inhibitory effect of E6 overexpression. We show that high levels of viral DNA amplification are critical for late protein expression and report several previously undescribed viral RNAs, including bicistronic transcripts predicted to encode E5 and L2 or an alternative form of E1^E4 and L1. PMID:23572574

LOH at 16p13 is a novel chromosomal alteration detected in benign and malignant microdissected papillary neoplasms of the breast.

PubMed

Lininger, R A; Park, W S; Man, Y G; Pham, T; MacGrogan, G; Zhuang, Z; Tavassoli, F A

1998-10-01

Papillary carcinoma of the breast is a variant of predominantly intraductal carcinoma characterized by a papillary growth pattern with fibrovascular support. Loss of heterozygosity (LOH) was evaluated at multiple chromosomal loci (including loci reported to show frequent genetic alterations in breast cancer) to determine the frequency of genetic mutations in these tumors and their precursors. Thirty-three papillary lesions of the breast (6 papillary carcinomas, 12 carcinomas arising in a papilloma, and 15 intraductal papillomas with florid epithelial hyperplasia) were retrieved from the files of the Armed Forces Institute of Pathology (AFIP). Tumor cells and normal tissue were microdissected in each case and screened for LOH at INT-2 and p53 as well as several loci on chromosome 16p13 in the TSC2/PKD1 gene region (D16S423, D16S663, D16S665). LOH on chromosome 16p13 was present in 10 of 16 (63%) informative cases of either papillary carcinoma or carcinoma arising in a papilloma as well as in 6 of 10 (60%) informative cases of intraductal papilloma with florid epithelial hyperplasia (IDH). One case showed simultaneous LOH in both the florid IDH and carcinoma components of a papilloma. LOH was not observed at either INT-2 or p53 in any of the papillary carcinomas or papillomas with florid IDH. In conclusion, a high frequency of LOH at chromosome 16p13 (the TSC2/PKD1 gene region) is in both papillary carcinomas of the breast as well as in papillomas with florid IDH, including a case with LOH present simultaneously in both components. These findings suggest that chromosome 16p contains a tumor suppressor gene that frequently is mutated early in papillary neoplasia.

Pathways of Metabolite-related Damage to A Synthetic p53 Gene Exon 7 Oligonucleotide using Magnetic Enzyme Bioreactor Beads and LC-MS/MS Sequencing.

PubMed

Malla, Spundana; Kadimisetty, Karteek; Jiang, Di; Choudhary, Dharamainder; Rusling, James F

2018-05-11

Reactive metabolites of environmental chemicals and drugs can cause site-specific damage to p53 tumor suppressor gene in a major pathway for genotoxicity. We report here a high throughput, cell-free, 96-well plate magnetic bead-enzyme system interfaced with LC-MS/MS sequencing to bioactivate test chemicals and identify resulting adduction sites on genes. Bioactivated aflatoxin B1 was reacted with a 32 bp exon 7 fragment of the p53 gene using 8 microsomal cyt P450 enzymes from different organs coated on magnetic beads. All cyt P450s converted aflatoxin B1 to aflatoxin B1-8,9-epoxide that adducts guanine (G) in codon 249, with subsequent depurination to give abasic sites, then strand breaks. This is the first demonstration in a cell-free medium that aflatoxin B1 metabolite selectively causes abasic site formation and strand breaks at codon 249 of the p53 probe, corresponding to the chemical pathway and mutations of p53 in human liver cells and tumors. Molecular modeling supports the view that binding of aflatoxin B1-8,9-epoxide to G in codon 249 precedes the SN2 adduction reaction. Among a range of metabolic enzymes characteristic of different organs, human liver microsomes and cyt P450 3A5 supersomes showed the highest bioactivation rate for p53 exon 7 damage. This method to identify metabolite-related gene damage sites may facilitate predictions of organ-specific cancers for test chemicals via correlations with mutation sites.

Comprehensive Genomic Characterization of Upper Tract Urothelial Carcinoma.

PubMed

Moss, Tyler J; Qi, Yuan; Xi, Liu; Peng, Bo; Kim, Tae-Beom; Ezzedine, Nader E; Mosqueda, Maribel E; Guo, Charles C; Czerniak, Bogdan A; Ittmann, Michael; Wheeler, David A; Lerner, Seth P; Matin, Surena F

2017-10-01

Upper urinary tract urothelial cancer (UTUC) may have unique etiologic and genomic factors compared to bladder cancer. To characterize the genomic landscape of UTUC and provide insights into its biology using comprehensive integrated genomic analyses. We collected 31 untreated snap-frozen UTUC samples from two institutions and carried out whole-exome sequencing (WES) of DNA, RNA sequencing (RNAseq), and protein analysis. Adjusting for batch effects, consensus mutation calls from independent pipelines identified DNA mutations, gene expression clusters using unsupervised consensus hierarchical clustering (UCHC), and protein expression levels that were correlated with relevant clinical variables, The Cancer Genome Atlas, and other published data. WES identified mutations in FGFR3 (74.1%; 92% low-grade, 60% high-grade), KMT2D (44.4%), PIK3CA (25.9%), and TP53 (22.2%). APOBEC and CpG were the most common mutational signatures. UCHC of RNAseq data segregated samples into four molecular subtypes with the following characteristics. Cluster 1: no PIK3CA mutations, nonsmokers, high-grade

Halogen-Enriched Fragment Libraries as Leads for Drug Rescue of Mutant p53

PubMed Central

2012-01-01

The destabilizing p53 cancer mutation Y220C creates a druggable surface crevice. We developed a strategy exploiting halogen bonding for lead discovery to stabilize the mutant with small molecules. We designed halogen-enriched fragment libraries (HEFLibs) as starting points to complement classical approaches. From screening of HEFLibs and subsequent structure-guided design, we developed substituted 2-(aminomethyl)-4-ethynyl-6-iodophenols as p53-Y220C stabilizers. Crystal structures of their complexes highlight two key features: (i) a central scaffold with a robust binding mode anchored by halogen bonding of an iodine with a main-chain carbonyl and (ii) an acetylene linker, enabling the targeting of an additional subsite in the crevice. The best binders showed induction of apoptosis in a human cancer cell line with homozygous Y220C mutation. Our structural and biophysical data suggest a more widespread applicability of HEFLibs in drug discovery. PMID:22439615

Antiangiogenesis and gene aberration-related therapy may improve overall survival in patients with concurrent KRAS and TP53 hotspot mutant cancer

PubMed Central

Wang, Zhijie; Piha-Paul, Sarina; Janku, Filip; Subbiah, Vivek; Shi, Naiyi; Gong, Jing; Wathoo, Chetna; Shaw, Kenna; Hess, Kenneth; Broaddus, Russell; Naing, Aung; Hong, David; Tsimberidou, Apostolia M.; Karp, Daniel; Yao, James; Meric-Bernstam, Funda; Fu, Siqing

2017-01-01

Purpose Genetic alterations such as activating KRAS and/or inactivating TP53 are thought to be the most common drivers to tumorigenesis. Therefore, we assessed phase I cancer patients with KRAS+/TP53+ mutations. Results Approximately 8% of patients referred to phase I clinical trials harbored concurrent KRAS and TP53 mutations. Patients who received a phase I trial therapy (n = 57) had a median OS of 12 months, compared with 4.6 months in those who were not treated (n = 106; p = 0.003). KRAS G13 and TP53 R273 mutations were associated with poor overall survival (OS), while antiangiogenesis and gene aberration-related therapies were associated with prolonged OS. A prognostic model using neutrophilia, thrombocytosis, hypoalbuminemia, body mass index <30 kg/m2, and the absence of lung metastasis was established and validated. Phase I cancer patients in the low-risk group had a median OS of 16.6 months compared with 5.4 months in the high-risk group (p < 0.001). Untreated patients in the low-risk group had a median OS of 6.7 months compared with 3.6 months in the high-risk group (p = 0.033). Experimental Design We analyzed 163 consecutive patients with advanced KRAS+/TP53+ mutant cancer who were referred to phase I clinical trials, to identify molecular aberrations, clinical characteristics, survivals, and potentially effective treatment regimens. Conclusions This study provided preliminary evidence that besides modulation of the proinflammatory state, antiangiogensis and concomitant gene aberration-related therapies may improve the treatment of KRAS+/TP53+ mutant cancer. PMID:28430579

Mammary-specific inactivation of E-cadherin and p53 impairs functional gland development and leads to pleomorphic invasive lobular carcinoma in mice.

PubMed

Derksen, Patrick W B; Braumuller, Tanya M; van der Burg, Eline; Hornsveld, Marten; Mesman, Elly; Wesseling, Jelle; Krimpenfort, Paul; Jonkers, Jos

2011-05-01

Breast cancer is the most common malignancy in women of the Western world. Even though a large percentage of breast cancer patients show pathological complete remission after standard treatment regimes, approximately 30-40% are non-responsive and ultimately develop metastatic disease. To generate a good preclinical model of invasive breast cancer, we have taken a tissue-specific approach to somatically inactivate p53 and E-cadherin, the cardinal cell-cell adhesion receptor that is strongly associated with tumor invasiveness. In breast cancer, E-cadherin is found mutated or otherwise functionally silenced in invasive lobular carcinoma (ILC), which accounts for 10-15% of all breast cancers. We show that mammary-specific stochastic inactivation of conditional E-cadherin and p53 results in impaired mammary gland function during pregnancy through the induction of anoikis resistance of mammary epithelium, resulting in loss of epithelial organization and a dysfunctional mammary gland. Moreover, combined inactivation of E-cadherin and p53 induced lactation-independent development of invasive and metastatic mammary carcinomas, which showed strong resemblance to human pleomorphic ILC. Dissemination patterns of mouse ILC mimic the human malignancy, showing metastasis to the gastrointestinal tract, peritoneum, lung, lymph nodes and bone. Our results confirm that loss of E-cadherin contributes to both mammary tumor initiation and metastasis, and establish a preclinical mouse model of human ILC that can be used for the development of novel intervention strategies to treat invasive breast cancer.

Comprehensive profiling and quantitation of oncogenic mutations in non small-cell lung carcinoma using single molecule amplification and re-sequencing technology

PubMed Central

Jiang, Hong; Wang, Limin; Xu, Rujun; Shi, Yanbin; Zhang, Jianguang; Xu, Mengnan; Cram, David S.; Ma, Shenglin

2016-01-01

Activating and resistance mutations in the tyrosine kinase domain of several oncogenes are frequently associated with non-small cell lung carcinoma (NSCLC). In this study we assessed the frequency, type and abundance of EGFR, KRAS, BRAF, TP53 and ALK mutations in tumour specimens from 184 patients with early and late stage disease using single molecule amplification and re-sequencing technology (SMART). Based on modelling of EGFR mutations, the detection sensitivity of the SMART assay was at least 0.1%. Benchmarking EGFR mutation detection against the gold standard ARMS-PCR assay, SMART assay had a sensitivity and specificity of 98.7% and 99.0%. Amongst the 184 samples, EGFR mutations were the most prevalent (59.9%), followed by KRAS (16.9%), TP53 (12.7%), EML4-ALK fusions (6.3%) and BRAF (4.2%) mutations. The abundance and types of mutations in tumour specimens were extremely heterogeneous, involving either monoclonal (51.6%) or polyclonal (12.6%) mutation events. At the clinical level, although the spectrum of tumour mutation(s) was unique to each patient, the overall patterns in early or advanced stage disease were relatively similar. Based on these findings, we propose that personalized profiling and quantitation of clinically significant oncogenic mutations will allow better classification of patients according to tumour characteristics and provide clinicians with important ancillary information for treatment decision-making. PMID:27409166

Comprehensive profiling and quantitation of oncogenic mutations in non small-cell lung carcinoma using single molecule amplification and re-sequencing technology.

PubMed

Zhang, Shirong; Xia, Bing; Jiang, Hong; Wang, Limin; Xu, Rujun; Shi, Yanbin; Zhang, Jianguang; Xu, Mengnan; Cram, David S; Ma, Shenglin

2016-08-02

Activating and resistance mutations in the tyrosine kinase domain of several oncogenes are frequently associated with non-small cell lung carcinoma (NSCLC). In this study we assessed the frequency, type and abundance of EGFR, KRAS, BRAF, TP53 and ALK mutations in tumour specimens from 184 patients with early and late stage disease using single molecule amplification and re-sequencing technology (SMART). Based on modelling of EGFR mutations, the detection sensitivity of the SMART assay was at least 0.1%. Benchmarking EGFR mutation detection against the gold standard ARMS-PCR assay, SMART assay had a sensitivity and specificity of 98.7% and 99.0%. Amongst the 184 samples, EGFR mutations were the most prevalent (59.9%), followed by KRAS (16.9%), TP53 (12.7%), EML4-ALK fusions (6.3%) and BRAF (4.2%) mutations. The abundance and types of mutations in tumour specimens were extremely heterogeneous, involving either monoclonal (51.6%) or polyclonal (12.6%) mutation events. At the clinical level, although the spectrum of tumour mutation(s) was unique to each patient, the overall patterns in early or advanced stage disease were relatively similar. Based on these findings, we propose that personalized profiling and quantitation of clinically significant oncogenic mutations will allow better classification of patients according to tumour characteristics and provide clinicians with important ancillary information for treatment decision-making.

Alpha-santalol, a chemopreventive agent against skin cancer, causes G2/M cell cycle arrest in both p53-mutated human epidermoid carcinoma A431 cells and p53 wild-type human melanoma UACC-62 cells

PubMed Central

2010-01-01

Background α-Santalol, an active component of sandalwood oil, has shown chemopreventive effects on skin cancer in different murine models. However, effects of α-santalol on cell cycle have not been studied. Thus, the objective of this study was to investigate effects of α-santalol on cell cycle progression in both p53 mutated human epidermoid carcinoma A431 cells and p53 wild-type human melanoma UACC-62 cells to elucidate the mechanism(s) of action. Methods MTT assay was used to determine cell viability in A431 cells and UACC-62; fluorescence-activated cell sorting (FACS) analysis of propidium iodide staining was used for determining cell cycle distribution in A431 cells and UACC-62 cells; immunoblotting was used for determining the expression of various proteins and protein complexes involved in the cell cycle progression; siRNA were used to knockdown of p21 or p53 in A431 and UACC-62 cells and immunofluorescence microscopy was used to investigate microtubules in UACC-62 cells. Results α-Santalol at 50-100 μM decreased cell viability from 24 h treatment and α-santalol at 50 μM-75 μM induced G2/M phase cell cycle arrest from 6 h treatment in both A431 and UACC-62 cells. α-Santalol altered expressions of cell cycle proteins such as cyclin A, cyclin B1, Cdc2, Cdc25c, p-Cdc25c and Cdk2. All of these proteins are critical for G2/M transition. α-Santalol treatment up-regulated the expression of p21 and suppressed expressions of mutated p53 in A431 cells; whereas, α-santalol treatment increased expressions of wild-type p53 in UACC-62 cells. Knockdown of p21 in A431 cells, knockdown of p21 and p53 in UACC-62 cells did not affect cell cycle arrest caused by α-santalol. Furthermore, α-santalol caused depolymerization of microtubules similar to vinblastine in UACC-62 cells. Conclusions This study for the first time identifies effects of α-santalol in G2/M phase arrest and describes detailed mechanisms of G2/M phase arrest by this agent, which might be contributing to its overall cancer preventive efficacy in various mouse skin cancer models. PMID:20682067

Basal brain oxidative and nitrative stress levels are finely regulated by the interplay between superoxide dismutase 2 and p53.

PubMed

Barone, Eugenio; Cenini, Giovanna; Di Domenico, Fabio; Noel, Teresa; Wang, Chi; Perluigi, Marzia; St Clair, Daret K; Butterfield, D Allan

2015-11-01

Superoxide dismutases (SODs) are the primary reactive oxygen species (ROS)-scavenging enzymes of the cell and catalyze the dismutation of superoxide radicals O2- to H2O2 and molecular oxygen (O2). Among the three forms of SOD identified, manganese-containing SOD (MnSOD, SOD2) is a homotetramer located wholly in the mitochondrial matrix. Because of the SOD2 strategic location, it represents the first mechanism of defense against the augmentation of ROS/reactive nitrogen species levels in the mitochondria for preventing further damage. This study seeks to understand the effects that the partial lack (SOD2(-/+) ) or the overexpression (TgSOD2) of MnSOD produces on oxidative/nitrative stress basal levels in different brain isolated cellular fractions (i.e., mitochondrial, nuclear, cytosolic) as well as in the whole-brain homogenate. Furthermore, because of the known interaction between SOD2 and p53 protein, this study seeks to clarify the impact that the double mutation has on oxidative/nitrative stress levels in the brain of mice carrying the double mutation (p53(-/-) × SOD2(-/+) and p53(-/-) × TgSOD2). We show that each mutation affects mitochondrial, nuclear, and cytosolic oxidative/nitrative stress basal levels differently, but, overall, no change or reduction of oxidative/nitrative stress levels was found in the whole-brain homogenate. The analysis of well-known antioxidant systems such as thioredoxin-1 and Nrf2/HO-1/BVR-A suggests their potential role in the maintenance of the cellular redox homeostasis in the presence of changes of SOD2 and/or p53 protein levels. © 2015 Wiley Periodicals, Inc.

Specific interaction of mutant p53 with regions of matrix attachment region DNA elements (MARs) with a high potential for base-unpairing

PubMed Central

Will, Katrin; Warnecke, Gabriele; Wiesmüller, Lisa; Deppert, Wolfgang

1998-01-01

Mutant, but not wild-type p53 binds with high affinity to a variety of MAR-DNA elements (MARs), suggesting that MAR-binding of mutant p53 relates to the dominant-oncogenic activities proposed for mutant p53. MARs recognized by mutant p53 share AT richness and contain variations of an AATATATTT “DNA-unwinding motif,” which enhances the structural dynamics of chromatin and promotes regional DNA base-unpairing. Mutant p53 specifically interacted with MAR-derived oligonucleotides carrying such unwinding motifs, catalyzing DNA strand separation when this motif was located within a structurally labile sequence environment. Addition of GC-clamps to the respective MAR-oligonucleotides or introducing mutations into the unwinding motif strongly reduced DNA strand separation, but supported the formation of tight complexes between mutant p53 and such oligonucleotides. We conclude that the specific interaction of mutant p53 with regions of MAR-DNA with a high potential for base-unpairing provides the basis for the high-affinity binding of mutant p53 to MAR-DNA. PMID:9811860

Mechanisms that enhance sustainability of p53 pulses.

PubMed

Kim, Jae Kyoung; Jackson, Trachette L

2013-01-01

The tumor suppressor p53 protein shows various dynamic responses depending on the types and extent of cellular stresses. In particular, in response to DNA damage induced by γ-irradiation, cells generate a series of p53 pulses. Recent research has shown the importance of sustaining repeated p53 pulses for recovery from DNA damage. However, far too little attention has been paid to understanding how cells can sustain p53 pulses given the complexities of genetic heterogeneity and intrinsic noise. Here, we explore potential molecular mechanisms that enhance the sustainability of p53 pulses by developing a new mathematical model of the p53 regulatory system. This model can reproduce many experimental results that describe the dynamics of p53 pulses. By simulating the model both deterministically and stochastically, we found three potential mechanisms that improve the sustainability of p53 pulses: 1) the recently identified positive feedback loop between p53 and Rorα allows cells to sustain p53 pulses with high amplitude over a wide range of conditions, 2) intrinsic noise can often prevent the dampening of p53 pulses even after mutations, and 3) coupling of p53 pulses in neighboring cells via cytochrome-c significantly reduces the chance of failure in sustaining p53 pulses in the presence of heterogeneity among cells. Finally, in light of these results, we propose testable experiments that can reveal important mechanisms underlying p53 dynamics.

Curcumin inhibits growth potential by G1 cell cycle arrest and induces apoptosis in p53-mutated COLO 320DM human colon adenocarcinoma cells.

PubMed

Dasiram, Jade Dhananjay; Ganesan, Ramamoorthi; Kannan, Janani; Kotteeswaran, Venkatesan; Sivalingam, Nageswaran

2017-02-01

Curcumin, a natural polyphenolic compound and it is isolated from the rhizome of Curcuma longa, have been reported to possess anticancer effect against stage I and II colon cancer. However, the effect of curcumin on colon cancer at Dukes' type C metastatic stage III remains still unclear. In the present study, we have investigated the anticancer effects of curcumin on p53 mutated COLO 320DM human colon adenocarcinoma cells derived from Dukes' type C metastatic stage. The cellular viability and proliferation were assessed by trypan blue exclusion assay and MTT assay, respectively. The cytotoxicity effect was examined by lactate dehydrogenase (LDH) cytotoxicity assay. Apoptosis was analyzed by DNA fragmentation analysis, Hoechst and propidium iodide double fluorescent staining and confocal microscopy analysis. Cell cycle distribution was performed by flow cytometry analysis. Here we have observed that curcumin treatment significantly inhibited the cellular viability and proliferation potential of p53 mutated COLO 320DM cells in a dose- and time-dependent manner. In addition, curcumin treatment showed no cytotoxic effects to the COLO 320DM cells. DNA fragmentation analysis, Hoechst and propidium iodide double fluorescent staining and confocal microscopy analysis revealed that curcumin treatment induced apoptosis in COLO 320DM cells. Furthermore, curcumin caused cell cycle arrest at the G1 phase, decreased the cell population in the S phase and induced apoptosis in COLO 320DM colon adenocarcinoma cells. Together, these data suggest that curcumin exerts anticancer effects and induces apoptosis in p53 mutated COLO 320DM human colon adenocarcinoma cells derived from Dukes' type C metastatic stage. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Characterizing genomic differences of human cancer stratified by the TP53 mutation status.

PubMed

Wang, Mengyao; Yang, Chao; Zhang, Xiuqing; Li, Xiangchun

2018-06-01

The key roles of the TP53 mutation in cancer have been well established. TP53 is the most frequently mutated gene, and its inactivation is widespread among human cancer types. However, the landscape of genomic alterations in human cancers stratified by the TP53 mutation has not yet been described. We obtained somatic mutation and copy number change data of 6551 regular-mutated samples from the Cancer Genome Atlas (TCGA) and compared significantly mutated genes (SMGs), copy number alterations, mutational signatures and mutational strand asymmetries between cancer samples with and without the TP53 mutation. We identified 126 SMGs, 30 of which were statistically significant in both the TP53 mutant and wild-type groups. Several SMGs, such as VHL, SMAD4 and PTEN, showed a mutation bias towards the TP53 wild-type group, whereas ATRX, IDH1 and RB1 were more prevalent in the TP53 mutant group. Five mutational signatures were extracted from the combined TCGA dataset on which mutational asymmetry analysis was performed, revealing that the TP53 mutant group exhibited substantially greater replication and transcription biases. Furthermore, we found that alterations of multiple genes in a merged mutually exclusive network composed of BRAF, EGFR, PAK1, PIK3CA, PTEN, APC and TERT were related to shortened survival in the TP53 wild-type group. In summary, we characterized the genomic differences and similarities underlying human cancers stratified by the TP53 mutation and identified multi-gene alterations of a merged mutually exclusive network to be a poor prognostic factor for the TP53 wild-type group.

De Novo Truncating Mutations in the Last and Penultimate Exons of PPM1D Cause an Intellectual Disability Syndrome.

PubMed

Jansen, Sandra; Geuer, Sinje; Pfundt, Rolph; Brough, Rachel; Ghongane, Priyanka; Herkert, Johanna C; Marco, Elysa J; Willemsen, Marjolein H; Kleefstra, Tjitske; Hannibal, Mark; Shieh, Joseph T; Lynch, Sally Ann; Flinter, Frances; FitzPatrick, David R; Gardham, Alice; Bernhard, Birgitta; Ragge, Nicola; Newbury-Ecob, Ruth; Bernier, Raphael; Kvarnung, Malin; Magnusson, E A Helena; Wessels, Marja W; van Slegtenhorst, Marjon A; Monaghan, Kristin G; de Vries, Petra; Veltman, Joris A; Lord, Christopher J; Vissers, Lisenka E L M; de Vries, Bert B A

2017-04-06

Intellectual disability (ID) is a highly heterogeneous disorder involving at least 600 genes, yet a genetic diagnosis remains elusive in ∼35%-40% of individuals with moderate to severe ID. Recent meta-analyses statistically analyzing de novo mutations in >7,000 individuals with neurodevelopmental disorders highlighted mutations in PPM1D as a possible cause of ID. PPM1D is a type 2C phosphatase that functions as a negative regulator of cellular stress-response pathways by mediating a feedback loop of p38-p53 signaling, thereby contributing to growth inhibition and suppression of stress-induced apoptosis. We identified 14 individuals with mild to severe ID and/or developmental delay and de novo truncating PPM1D mutations. Additionally, deep phenotyping revealed overlapping behavioral problems (ASD, ADHD, and anxiety disorders), hypotonia, broad-based gait, facial dysmorphisms, and periods of fever and vomiting. PPM1D is expressed during fetal brain development and in the adult brain. All mutations were located in the last or penultimate exon, suggesting escape from nonsense-mediated mRNA decay. Both PPM1D expression analysis and cDNA sequencing in EBV LCLs of individuals support the presence of a stable truncated transcript, consistent with this hypothesis. Exposure of cells derived from individuals with PPM1D truncating mutations to ionizing radiation resulted in normal p53 activation, suggesting that p53 signaling is unaffected. However, a cell-growth disadvantage was observed, suggesting a possible effect on the stress-response pathway. Thus, we show that de novo truncating PPM1D mutations in the last and penultimate exons cause syndromic ID, which provides additional insight into the role of cell-cycle checkpoint genes in neurodevelopmental disorders. Copyright © 2017 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

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

Kirsch, David G., E-mail: david.kirsch@duke.ed; Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA; Departments of Radiation Oncology and Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC

Purpose: To image a genetically engineered mouse model of non-small-cell lung cancer with micro-computed tomography (micro-CT) to measure tumor response to radiation therapy. Methods and Materials: The Cre-loxP system was used to generate primary lung cancers in mice with mutation in K-ras alone or in combination with p53 mutation. Mice were serially imaged by micro-CT, and tumor volumes were determined. A comparison of tumor volume by micro-CT and tumor histology was performed. Tumor response to radiation therapy (15.5 Gy) was assessed with micro-CT. Results: The tumor volume measured with free-breathing micro-CT scans was greater than the volume calculated by histology.more » Nevertheless, this imaging approach demonstrated that lung cancers with mutant p53 grew more rapidly than lung tumors with wild-type p53 and also showed that radiation therapy increased the doubling time of p53 mutant lung cancers fivefold. Conclusions: Micro-CT is an effective tool to noninvasively measure the growth of primary lung cancers in genetically engineered mice and assess tumor response to radiation therapy. This imaging approach will be useful to study the radiation biology of lung cancer.« less

Redox Regulation in Bone Marrow Failure

DTIC Science & Technology

2012-06-01

Fanconi anemia mutation for hematopoietic senescence. J Cell Sci, 2007. 120(Pt 9): p. 1572-83. 2. Aylon, Y. and M. Oren, Living with p53, dying of p53...aplastic anemia patients with a p38 MAPK inhibitor can restore defective hematopoietic activity, suggesting the critical role of p38 in bone marrow...hematopoietic stem cells, and eventually leading to bone marrow failure [7, 8] [9] [10]. On the other hand, treating aplastic anemia patients with a p38

An ultrasensitive colorimeter assay strategy for p53 mutation assisted by nicking endonuclease signal amplification.

PubMed

Lin, Zhenyu; Yang, Weiqiang; Zhang, Guiyun; Liu, Qida; Qiu, Bin; Cai, Zongwei; Chen, Guonan

2011-08-28

A novel catalytic colorimetric assay assisted by nicking endonuclease signal amplification (NESA) was developed. With the signal amplification, the detection limit of the p53 target gene can be as low as 1 pM, which is nearly 5 orders of magnitude lower than that of other previously reported colorimetric DNA detection strategies based on catalytic DNAzyme.

Interaction between the Cockayne syndrome B and p53 proteins: implications for aging.

PubMed

Frontini, Mattia; Proietti-De-Santis, Luca

2012-02-01

The CSB protein plays a role in the transcription coupled repair (TCR) branch of the nucleotide excision repair pathway. CSB is very often found mutated in Cockayne syndrome, a segmental progeroid genetic disease characterized by organ degeneration and growth failure. The tumor suppressor p53 plays a pivotal role in triggering senescence and apoptosis and suppressing tumorigenesis. Although p53 is very important to avoid cancer, its excessive activity can be detrimental for the lifespan of the organism. This is why a network of positive and negative feedback loops, which most likely evolved to fine-tune the activity of this tumor suppressor, modulate its induction and activation. Accordingly, an unbalanced p53 activity gives rise to premature aging or cancer. The physical interaction between CSB and p53 proteins has been known for more than a decade but, despite several hypotheses, nobody has been able to show the functional consequences of this interaction. In this review we resume recent advances towards a more comprehensive understanding of the critical role of this interaction in modulating p53’s levels and activity, therefore helping the system find a reasonable equilibrium between the beneficial and the detrimental effects of its activity. This crosstalk re-establishes the physiological balance towards cell proliferation and survival instead of towards cell death, after stressors of a broad nature. Accordingly, cells bearing mutations in the csb gene are unable to re-establish this physiological balance and to properly respond to some stress stimuli and undergo massive apoptosis.

Induction of the 5S RNP-Mdm2-p53 ribosomal stress pathway delays the initiation but fails to eradicate established murine acute myeloid leukemia.

PubMed

Jaako, P; Ugale, A; Wahlestedt, M; Velasco-Hernandez, T; Cammenga, J; Lindström, M S; Bryder, D

2017-01-01

Mutations resulting in constitutive activation of signaling pathways that regulate ribosome biogenesis are among the most common genetic events in acute myeloid leukemia (AML). However, whether ribosome biogenesis presents as a therapeutic target to treat AML remains unexplored. Perturbations in ribosome biogenesis trigger the 5S ribonucleoprotein particle (RNP)-Mdm2-p53 ribosomal stress pathway, and induction of this pathway has been shown to have therapeutic efficacy in Myc-driven lymphoma. In the current study we address the physiological and therapeutic role of the 5S RNP-Mdm2-p53 pathway in AML. By utilizing mice that have defective ribosome biogenesis due to downregulation of ribosomal protein S19 (Rps19), we demonstrate that induction of the 5S RNP-Mdm2-p53 pathway significantly delays the initiation of AML. However, even a severe Rps19 deficiency that normally results in acute bone marrow failure has no consistent efficacy on already established disease. Finally, by using mice that harbor a mutation in the Mdm2 gene disrupting its binding to 5S RNP, we show that loss of the 5S RNP-Mdm2-p53 pathway is dispensable for development of AML. Our study suggests that induction of the 5S RNP-Mdm2-p53 ribosomal stress pathway holds limited potential as a single-agent therapy in the treatment of AML.

Next generation sequencing survey of biliary tract cancer (BTC) reveals the association between tumor somatic variants and chemotherapy resistance

PubMed Central

Ahn, Daniel H.; Javle, Milind; Ahn, Chul W.; Jain, Apurva; Mikhail, Sameh; Noonan, Anne M.; Wu, Christina; Shroff, Rachna T.

2016-01-01

Background BTC are uncommon and associated with a dismal prognosis. Gemcitabine and platinum-combinations (GP) form the standard approach for treating advanced BTC. To characterize the spectrum of mutations and to identify potential biomarkers for GP response in BTC, we evaluated the genomic landscape and assessed whether mutations affecting DNA repair were associated with GP resistance. Methods Pretreatment FFPE samples from 183 BTC patients treated with GP were analyzed. Cox regression models were used to determine the association between mutations, progression free survival (PFS) and overall survival (OS). Results Considering genes with an incidence >10%, no individual gene was independently predictive of GP response. In patients with unresectable BTC who received GP as first-line therapy, the joint status of CDKN2A, TP53 and ARID1A were associated with PFS (P=0.0004) and OS (P=<0.0001). Patients with mutations in CDKN2A and TP53 were identified as a poor prognostic cohort with a median PFS and OS of 2.63 and 5.22 months. Patients with mutant ARID1A regardless of single mutational status of TP53 or CDKN2A had similar outcomes. A patient who exhibited mutations in all three genes had a median PFS of 20.37 months and OS not reached. Conclusions In the largest exploratory analysis of this nature in BTC, the presence of three prevalent, mutually exclusive mutations represents distinct patient cohorts. These mutations are prognostic and may represent a predictive biomarker to GP response. Prospective studies validate these findings are needed, including the incorporation of therapies that exploit the genomic instability observed with these mutations in BTC. PMID:27495988

Andrographolide induces degradation of mutant p53 via activation of Hsp70.

PubMed

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

2018-05-22

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

Copy number neutral loss of heterozygosity at 17p and homozygous mutations of TP53 are associated with complex chromosomal aberrations in patients newly diagnosed with myelodysplastic syndromes.

PubMed

Svobodova, Karla; Zemanova, Zuzana; Lhotska, Halka; Novakova, Milena; Podskalska, Lucie; Belickova, Monika; Brezinova, Jana; Sarova, Iveta; Izakova, Silvia; Lizcova, Libuse; Berkova, Adela; Siskova, Magda; Jonasova, Anna; Cermak, Jaroslav; Michalova, Kyra

2016-03-01

Complex karyotypes are seen in approximately 20% of patients with myelodysplastic syndromes (MDS) and are associated with a high risk of transformation to acute myeloid leukemia and poor outcomes in patients. Copy number neutral loss of heterozygosity (CN-LOH, i.e., both copies of a chromosomal pair or their parts originate from one parent) might contribute to increased genomic instability in the bone-marrow cells of patients with MDS. The pathological potential of CN-LOH, which arises as a clonal aberration in a proportion of somatic cells, consists of tumor suppressor gene and oncogene homozygous mutations. The aim of our study was to evaluate the frequency of CN-LOH at 17p in bone-marrow cells of newly diagnosed MDS patients with complex chromosomal aberrations and to assess its correlation with mutations in the TP53 gene (17p13.1). CN-LOH was detected in 40 chromosomal regions in 21 (29%) of 72 patients analyzed. The changes in 27 of the 40 regions identified were sporadic. The most common finding was CN-LOH of the short arm of chromosome 17, which was detected in 13 (18%) of 72 patients. A mutational analysis confirmed the homozygous mutation of TP53 in all CN-LOH 17p patients, among which two frameshift mutations are not registered in the International Agency for Research on Cancer TP53 Database. CN-LOH 17p correlated with aggressive disease (median overall survival 4 months) and was strongly associated with a complex karyotype in the cohort studied, which might cause rapid disease progression in high-risk MDS. No other CN-LOH region previously recorded in MDS or AML patients (1p, 4q, 7q, 11q, 13q, 19q, 21q) was detected in our cohort of patients with complex karyotype examined at the diagnosis of MDS. The LOH region appeared to be balanced (i.e., with no DNA copy number change) when examined with conventional and molecular cytogenetic methods. Therefore, a microarray that detects single-nucleotide polymorphisms is an ideal method with which to identify and further characterize CN-LOH. Our data should specify the prognosis and should lead to the identification of potential targets for therapeutic interventions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nonoverlapping Clinical and Mutational Patterns in Melanomas from the Female Genital Tract and Atypical Genital Nevi.

PubMed

Yélamos, Oriol; Merkel, Emily A; Sholl, Lauren Meldi; Zhang, Bin; Amin, Sapna M; Lee, Christina Y; Guitart, Gerta E; Yang, Jingyi; Wenzel, Alexander T; Bunick, Christopher G; Yazdan, Pedram; Choi, Jaehyuk; Gerami, Pedram

2016-09-01

Genital melanomas (GM) are the second most common cancer of the female external genitalia and may be confused with atypical genital nevi (AGN), which exhibit atypical histological features but have benign behavior. In this study, we compared the clinical, histological, and molecular features of 19 GM and 25 AGN. We described chromosomal copy number aberrations and the mutational status of 50 oncogenes and tumor suppressor genes in both groups. Our study showed that a pigmented lesion occurring in mucosal tissue, particularly in postmenopausal women, was more likely to be a melanoma than a nevus. GM had high levels of chromosomal instability, with many copy number aberrations. Furthermore, we found a completely nonoverlapping pattern of oncogenic mutations when comparing GM and AGN. In GM, we report somatic mutations in KIT and TP53. Conversely, AGN had frequent BRAF V600E mutations, which were not seen in any of the GM. Our results show that GM and AGN have distinct clinical and molecular changes and that GM have a different mutational pattern compared with AGN. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Individual crypt genetic heterogeneity and the origin of metaplastic glandular epithelium in human Barrett’s oesophagus

PubMed Central

Leedham, S J; Preston, S L; McDonald, S A C; Elia, G; Bhandari, P; Poller, D; Harrison, R; Novelli, M R; Jankowski, J A; Wright, N A

2008-01-01

Objectives: Current models of clonal expansion in human Barrett’s oesophagus are based upon heterogenous, flow-purified biopsy analysis taken at multiple segment levels. Detection of identical mutation fingerprints from these biopsy samples led to the proposal that a mutated clone with a selective advantage can clonally expand to fill an entire Barrett’s segment at the expense of competing clones (selective sweep to fixation model). We aimed to assess clonality at a much higher resolution by microdissecting and genetically analysing individual crypts. The histogenesis of Barrett’s metaplasia and neo-squamous islands has never been demonstrated. We investigated the oesophageal gland squamous ducts as the source of both epithelial sub-types. Methods: Individual crypts across Barrett’s biopsy and oesophagectomy blocks were dissected. Determination of tumour suppressor gene loss of heterozygosity patterns, p16 and p53 point mutations were carried out on a crypt-by-crypt basis. Cases of contiguous neo-squamous islands and columnar metaplasia with oesophageal squamous ducts were identified. Tissues were isolated by laser capture microdissection and genetically analysed. Results: Individual crypt dissection revealed mutation patterns that were masked in whole biopsy analysis. Dissection across oesophagectomy specimens demonstrated marked clonal heterogeneity, with multiple independent clones present. We identified a p16 point mutation arising in the squamous epithelium of the oesophageal gland duct, which was also present in a contiguous metaplastic crypt, whereas neo-squamous islands arising from squamous ducts were wild-type with respect to surrounding Barrett’s dysplasia. Conclusions: By studying clonality at the crypt level we demonstrate that Barrett’s heterogeneity arises from multiple independent clones, in contrast to the selective sweep to fixation model of clonal expansion previously described. We suggest that the squamous gland ducts situated throughout the oesophagus are the source of a progenitor cell that may be susceptible to gene mutation resulting in conversion to Barrett’s metaplastic epithelium. Additionally, these data suggest that wild-type ducts may be the source of neo-squamous islands. PMID:18305067

TP53 mutation and survival in aggressive B cell lymphoma.

PubMed

Zenz, Thorsten; Kreuz, Markus; Fuge, Maxi; Klapper, Wolfram; Horn, Heike; Staiger, Annette M; Winter, Doris; Helfrich, Hanne; Huellein, Jennifer; Hansmann, Martin-Leo; Stein, Harald; Feller, Alfred; Möller, Peter; Schmitz, Norbert; Trümper, Lorenz; Loeffler, Markus; Siebert, Reiner; Rosenwald, Andreas; Ott, German; Pfreundschuh, Michael; Stilgenbauer, Stephan

2017-10-01

TP53 is mutated in 20-25% of aggressive B-cell lymphoma (B-NHL). To date, no studies have addressed the impact of TP53 mutations in prospective clinical trial cohorts. To evaluate the impact of TP53 mutation to current risk models in aggressive B-NHL, we investigated TP53 gene mutations within the RICOVER-60 trial. Of 1,222 elderly patients (aged 61-80 years) enrolled in the study and randomized to six or eight cycles of CHOP-14 with or without Rituximab (NCT00052936), 265 patients were analyzed for TP53 mutations. TP53 mutations were demonstrated in 63 of 265 patients (23.8%). TP53 mutation was associated with higher LDH (65% vs. 37%; p < 0.001), higher international prognostic index-Scores (IPI 4/5 27% vs. 12%; p = 0.025) and B-symptoms (41% vs. 24%; p = 0.011). Patients with TP53 mutation were less likely to obtain a complete remission CR/CRu (CR unconfirmed) 61.9% (mut) vs. 79.7% (wt) (p = 0.007). TP53 mutations were associated with decreased event-free (EFS), progression-free (PFS) and overall survival (OS) (median observation time of 40.2 months): the 3 year EFS, PFS and OS were 42% (vs. 60%; p = 0.012), 42% (vs. 67.5%; p < 0.001) and 50% (vs. 76%; p < 0.001) for the TP53 mutation group. In a Cox proportional hazard analysis adjusting for IPI-factors and treatment arms, TP53 mutation was shown to be an independent predictor of EFS (HR 1.5), PFS (HR 2.0) and OS (HR 2.3; p < 0.001). TP53 mutations are independent predictors of survival in untreated patients with aggressive CD20+ lymphoma. TP53 mutations should be considered for risk models in DLBCL and strategies to improve outcome for patients with mutant TP53 must be developed. © 2017 UICC.

Real-world results of ibrutinib in patients with relapsed or refractory chronic lymphocytic leukemia: data from 95 consecutive patients treated in a compassionate use program. A study from the Swedish Chronic Lymphocytic Leukemia Group

PubMed Central

Winqvist, Maria; Asklid, Anna; Andersson, PO; Karlsson, Karin; Karlsson, Claes; Lauri, Birgitta; Lundin, Jeanette; Mattsson, Mattias; Norin, Stefan; Sandstedt, Anna; Hansson, Lotta; Österborg, Anders

2016-01-01

Ibrutinib, a Bruton’s tyrosine kinase inhibitor is approved for relapsed/refractory and del(17p)/TP53 mutated chronic lymphocytic leukemia. Discrepancies between clinical trials and routine health-care are commonly observed in oncology. Herein we report real-world results for 95 poor prognosis Swedish patients treated with ibrutinib in a compassionate use program. Ninety-five consecutive patients (93 chronic lymphocytic leukemia, 2 small lymphocytic leukemia) were included in the study between May 2014 and May 2015. The median age was 69 years. 63% had del(17p)/TP53 mutation, 65% had Rai stage III/IV, 28% had lymphadenopathy ≥10cm. Patients received ibrutinib 420 mg once daily until progression. At a median follow-up of 10.2 months, the overall response rate was 84% (consistent among subgroups) and 77% remained progression-free. Progression-free survival and overall survival were significantly shorter in patients with del(17p)/TP53 mutation (P=0.017 and P=0.027, log-rank test); no other factor was significant in Cox proportional regression hazards model. Ibrutinib was well tolerated. Hematomas occurred in 46% of patients without any major bleeding. Seven patients had Richter’s transformation. This real-world analysis on consecutive chronic lymphocytic leukemia patients from a well-defined geographical region shows the efficacy and safety of ibrutinib to be similar to that of pivotal trials. Yet, del(17p)/TP53 mutation remains a therapeutic challenge. Since not more than half of our patients would have qualified for the pivotal ibrutinib trial (RESONATE), our study emphasizes that real-world results should be carefully considered in future with regards to new agents and new indications in chronic lymphocytic leukemia. PMID:27198718

Real-world results of ibrutinib in patients with relapsed or refractory chronic lymphocytic leukemia: data from 95 consecutive patients treated in a compassionate use program. A study from the Swedish Chronic Lymphocytic Leukemia Group.

PubMed

Winqvist, Maria; Asklid, Anna; Andersson, P O; Karlsson, Karin; Karlsson, Claes; Lauri, Birgitta; Lundin, Jeanette; Mattsson, Mattias; Norin, Stefan; Sandstedt, Anna; Hansson, Lotta; Österborg, Anders

2016-12-01

Ibrutinib, a Bruton's tyrosine kinase inhibitor is approved for relapsed/refractory and del(17p)/TP53 mutated chronic lymphocytic leukemia. Discrepancies between clinical trials and routine health-care are commonly observed in oncology. Herein we report real-world results for 95 poor prognosis Swedish patients treated with ibrutinib in a compassionate use program. Ninety-five consecutive patients (93 chronic lymphocytic leukemia, 2 small lymphocytic leukemia) were included in the study between May 2014 and May 2015. The median age was 69 years. 63% had del(17p)/TP53 mutation, 65% had Rai stage III/IV, 28% had lymphadenopathy ≥10cm. Patients received ibrutinib 420 mg once daily until progression. At a median follow-up of 10.2 months, the overall response rate was 84% (consistent among subgroups) and 77% remained progression-free. Progression-free survival and overall survival were significantly shorter in patients with del(17p)/TP53 mutation (P=0.017 and P=0.027, log-rank test); no other factor was significant in Cox proportional regression hazards model. Ibrutinib was well tolerated. Hematomas occurred in 46% of patients without any major bleeding. Seven patients had Richter's transformation. This real-world analysis on consecutive chronic lymphocytic leukemia patients from a well-defined geographical region shows the efficacy and safety of ibrutinib to be similar to that of pivotal trials. Yet, del(17p)/TP53 mutation remains a therapeutic challenge. Since not more than half of our patients would have qualified for the pivotal ibrutinib trial (RESONATE), our study emphasizes that real-world results should be carefully considered in future with regards to new agents and new indications in chronic lymphocytic leukemia. Copyright© Ferrata Storti Foundation.

A porcine model of osteosarcoma

PubMed Central

Saalfrank, A; Janssen, K-P; Ravon, M; Flisikowski, K; Eser, S; Steiger, K; Flisikowska, T; Müller-Fliedner, P; Schulze, É; Brönner, C; Gnann, A; Kappe, E; Böhm, B; Schade, B; Certa, U; Saur, D; Esposito, I; Kind, A; Schnieke, A

2016-01-01

We previously produced pigs with a latent oncogenic TP53 mutation. Humans with TP53 germline mutations are predisposed to a wide spectrum of early-onset cancers, predominantly breast, brain, adrenal gland cancer, soft tissue sarcomas and osteosarcomas. Loss of p53 function has been observed in >50% of human cancers. Here we demonstrate that porcine mesenchymal stem cells (MSCs) convert to a transformed phenotype after activation of latent oncogenic TP53R167H and KRASG12D, and overexpression of MYC promotes tumorigenesis. The process mimics key molecular aspects of human sarcomagenesis. Transformed porcine MSCs exhibit genomic instability, with complex karyotypes, and develop into sarcomas on transplantation into immune-deficient mice. In pigs, heterozygous knockout of TP53 was sufficient for spontaneous osteosarcoma development in older animals, whereas homozygous TP53 knockout resulted in multiple large osteosarcomas in 7–8-month-old animals. This is the first report that engineered mutation of an endogenous tumour-suppressor gene leads to invasive cancer in pigs. Unlike in Trp53 mutant mice, osteosarcoma developed in the long bones and skull, closely recapitulating the human disease. These animals thus promise a model for juvenile osteosarcoma, a relatively uncommon but devastating disease. PMID:26974205

Characterisation of the p53 pathway in cell lines established from TH-MYCN transgenic mouse tumours.

PubMed

Chen, Lindi; Esfandiari, Arman; Reaves, William; Vu, Annette; Hogarty, Michael D; Lunec, John; Tweddle, Deborah A

2018-03-01

Cell lines established from the TH-MYCN transgenic murine model of neuroblastoma are a valuable preclinical, immunocompetent, syngeneic model of neuroblastoma, for which knowledge of their p53 pathway status is important. In this study, the Trp53 status and functional response to Nutlin-3 and ionising radiation (IR) were determined in 6 adherent TH-MYCN transgenic cell lines using Sanger sequencing, western blot analysis and flow cytometry. Sensitivity to structurally diverse MDM2 inhibitors (Nutlin-3, MI-63, RG7388 and NDD0005) was determined using XTT proliferation assays. In total, 2/6 cell lines were Trp53 homozygous mutant (NHO2A and 844MYCN+/+) and 1/6 (282MYCN+/-) was Trp53 heterozygous mutant. For 1/6 cell lines (NHO2A), DNA from the corresponding primary tumour was found to be Trp53 wt. In all cases, the presence of a mutation was consistent with aberrant p53 signalling in response to Nutlin-3 and IR. In comparison to TP53 wt human neuroblastoma cells, Trp53 wt murine control and TH-MYCN cell lines were significantly less sensitive to growth inhibition mediated by MI-63 and RG7388. These murine Trp53 wt and mutant TH-MYCN cell lines are useful syngeneic, immunocompetent neuroblastoma models, the former to test p53-dependent therapies in combination with immunotherapies, such as anti-GD2, and the latter as models of chemoresistant relapsed neuroblastoma when aberrations in the p53 pathway are more common. The spontaneous development of Trp53 mutations in 3 cell lines from TH-MYCN mice may have arisen from MYCN oncogenic driven and/or ex vivo selection. The identified species-dependent selectivity of MI-63 and RG7388 should be considered when interpreting in vivo toxicity studies of MDM2 inhibitors.

Association between mutations of critical pathway genes and survival outcomes according to the tumor location in colorectal cancer.

PubMed

Lee, Dae-Won; Han, Sae-Won; Cha, Yongjun; Bae, Jeong Mo; Kim, Hwang-Phill; Lyu, Jaemyun; Han, Hyojun; Kim, Hyoki; Jang, Hoon; Bang, Duhee; Huh, Iksoo; Park, Taesung; Won, Jae-Kyung; Jeong, Seung-Yong; Park, Kyu Joo; Kang, Gyeong Hoon; Kim, Tae-You

2017-09-15

Colorectal cancer (CRC) develops through the alteration of several critical pathways. This study was aimed at evaluating the influence of critical pathways on survival outcomes for patients with CRC. Targeted next-generation sequencing of 40 genes included in the 5 critical pathways of CRC (WNT, P53, RTK-RAS, phosphatidylinositol-4,5-bisphosphate 3-kinase [PI3K], and transforming growth factor β [TGF-β]) was performed for 516 patients with stage III or high-risk stage II CRC treated with surgery followed by adjuvant fluoropyrimidine and oxaliplatin chemotherapy. The associations between critical pathway mutations and relapse-free survival (RFS) and overall survival were analyzed. The associations were further analyzed according to the tumor location. The mutation rates for the WNT, P53, RTK-RAS, PI3K, and TGF-β pathways were 84.5%, 69.0%, 60.7%, 30.0%, and 28.9%, respectively. A mutation in the PI3K pathway was associated with longer RFS (adjusted hazard ratio [HR], 0.59; 95% confidence interval [CI], 0.36-0.99), whereas a mutation in the RTK-RAS pathway was associated with shorter RFS (adjusted HR, 1.60; 95% CI, 1.01-2.52). Proximal tumors showed a higher mutation rate than distal tumors, and the mutation profile was different according to the tumor location. The mutation rates of Kirsten rat sarcoma viral oncogene homolog (KRAS), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA), and B-Raf proto-oncogene serine/threonine kinase (BRAF) were higher in proximal tumors, and the mutation rates of adenomatous polyposis coli (APC), tumor protein 53 (TP53), and neuroblastoma RAS viral oncogene homolog (NRAS) were higher in distal tumors. The better RFS with the PI3K pathway mutation was significant only for proximal tumors, and the worse RFS with the RTK-RAS pathway mutation was significant only for distal tumors. A PI3K pathway mutation was associated with better RFS for CRC patients treated with adjuvant chemotherapy, and an RTK-RAS pathway mutation was associated with worse RFS. The significance of the prognostic impact differed according to the tumor location. Cancer 2017;123:3513-23. © 2017 American Cancer Society. © 2017 American Cancer Society.

Polymorphism of the cytochrome P450 CYP2D6 gene in a European population: characterization of 48 mutations and 53 alleles, their frequencies and evolution.

PubMed

Marez, D; Legrand, M; Sabbagh, N; Lo Guidice, J M; Spire, C; Lafitte, J J; Meyer, U A; Broly, F

1997-06-01

The polymorphic cytochrome P450 CYP2D6 is involved in the metabolism of various drugs of wide therapeutic use and is a presumed susceptibility factor for certain environmentally-induced diseases. Our aim was to define the mutations and alleles of the CYP2D6 gene and to evaluate their frequencies in the European population. Using polymerase chain reaction-single strand conformation polymorphism analysis, 672 unrelated subjects were screened for mutations in the 9 exons of the gene and their exon-intron boundaries. A total of 48 point mutations were identified, of which 29 were novel. Mutations 1749 G-->C, 2938 C-->T and 4268 G-->C represented 52.6%, 34.3% and 52.9% of the mutations in the total population, respectively. Of the eight detrimental mutations detected, the 1934 G-->A, the 1795 Tdel and the 2637 Adel accounted for 65.8%, 6.2% and 4.8% respectively, within the poor metabolizer subgroup. Fifty-three different alleles were characterized from the mutation pattern and by allele-specific sequencing. They are derived from three major alleles, namely the wild-type CYP2D6*1A, the functional CYP2D6*2 and the null CYP2D6*4A. Five allelic variants (CYP2D6*1A, *2, *2B, *4A and *5) account for about 87% of all alleles, while the remaining alleles occur with a frequency of 0.1%-2.7%. These data provide a solid basis for future epidemiological, clinical as well as interethnic studies of the CYP2D6 polymorphism and highlight that the described single strand conformation polymorphism method can be successfully used in designing such studies.

Aspm sustains postnatal cerebellar neurogenesis and medulloblastoma growth in mice

PubMed Central

Williams, Scott E.; Garcia, Idoia; Crowther, Andrew J.; Li, Shiyi; Stewart, Alyssa; Liu, Hedi; Lough, Kendall J.; O'Neill, Sean; Veleta, Katherine; Oyarzabal, Esteban A.; Merrill, Joseph R.; Shih, Yen-Yu Ian; Gershon, Timothy R.

2015-01-01

Alterations in genes that regulate brain size may contribute to both microcephaly and brain tumor formation. Here, we report that Aspm, a gene that is mutated in familial microcephaly, regulates postnatal neurogenesis in the cerebellum and supports the growth of medulloblastoma, the most common malignant pediatric brain tumor. Cerebellar granule neuron progenitors (CGNPs) express Aspm when maintained in a proliferative state by sonic hedgehog (Shh) signaling, and Aspm is expressed in Shh-driven medulloblastoma in mice. Genetic deletion of Aspm reduces cerebellar growth, while paradoxically increasing the mitotic rate of CGNPs. Aspm-deficient CGNPs show impaired mitotic progression, altered patterns of division orientation and differentiation, and increased DNA damage, which causes progenitor attrition through apoptosis. Deletion of Aspm in mice with Smo-induced medulloblastoma reduces tumor growth and increases DNA damage. Co-deletion of Aspm and either of the apoptosis regulators Bax or Trp53 (also known as p53) rescues the survival of neural progenitors and reduces the growth restriction imposed by Aspm deletion. Our data show that Aspm functions to regulate mitosis and to mitigate DNA damage during CGNP cell division, causes microcephaly through progenitor apoptosis when mutated, and sustains tumor growth in medulloblastoma. PMID:26450969

PTEN is a potent suppressor of small cell lung cancer.

PubMed

Cui, Min; Augert, Arnaud; Rongione, Michael; Conkrite, Karina; Parazzoli, Susan; Nikitin, Alexander Yu; Ingolia, Nicholas; MacPherson, David

2014-05-01

Small cell lung carcinoma (SCLC) is a highly metastatic tumor type with neuroendocrine features and a dismal prognosis. PTEN mutations and PIK3CA activating mutations have been reported in SCLC but the functional relevance of this pathway is unknown. The PTEN/PIK3CA pathway was interrogated using an AdenoCre-driven mouse model of SCLC harboring inactivated Rb and p53. Inactivation of one allele of PTEN in Rb/p53-deleted mice led to accelerated SCLC with frequent metastasis to the liver. In contrast with the high mutation burden reported in human SCLC, exome analyses revealed a low number of protein-altering mutations in mouse SCLC. Inactivation of both alleles of PTEN in the Rb/p53-deleted system led to nonmetastatic adenocarcinoma with neuroendocrine differentiation. This study reveals a critical role for the PTEN/PI3K pathway in both SCLC and lung adenocarcinoma and provides an ideal system to test the phosphoinositide 3-kinase (PI3K) pathway inhibitors as targeted therapy for subsets of patients with SCLC. The ability of PTEN inactivation to accelerate SCLC in a genetic mouse model suggests that targeting the PTEN pathway is a therapeutic option for a subset of human patients with SCLC. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/early/2014/04/28/1541-7786.MCR-13-0554/F1.large.jpg. ©2014 AACR.

Concordant p53 and mdm-2 protein expression in vulvar squamous cell carcinoma and adjacent lichen sclerosus.

PubMed

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

2001-06-01

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

Amino-terminal residues of ΔNp63, mutated in ectodermal dysplasia, are required for its transcriptional activity.

PubMed

Lena, Anna Maria; Duca, Sara; Novelli, Flavia; Melino, Sonia; Annicchiarico-Petruzzelli, Margherita; Melino, Gerry; Candi, Eleonora

2015-11-13

p63, a member of the p53 family, is a crucial transcription factor for epithelial development and skin homeostasis. Heterozygous mutations in TP63 gene have been associated with human ectodermal dysplasia disorders. Most of these TP63 mutations are missense mutations causing amino acidic substitutions at p63 DNA binding or SAM domains that reduce or abolish the transcriptional activity of mutants p63. A significant number of mutants, however, resides in part of the p63 protein that apparently do not affect DNA binding and/or transcriptional activity, such as the N-terminal domain. Here, we characterize five p63 mutations at the 5' end of TP63 gene aiming to understand the pathogenesis of the diseases and to uncover the role of ΔNp63α N-terminus residues in determining its transactivation potential. Copyright © 2015 Elsevier Inc. All rights reserved.

Pattern of Expression of p53, Its Family Members, and Regulators during Early Ocular Development and in the Post-Mitotic Retina

PubMed Central

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

2012-01-01

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

Mutant p53 establishes targetable tumor dependency by promoting unscheduled replication

PubMed Central

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

2017-01-01

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

Combining isothermal rolling circle amplification and electrochemiluminescence for highly sensitive point mutation detection

NASA Astrophysics Data System (ADS)

Su, Qiang; Zhou, Xiaoming

2008-12-01

Many pathogenic and genetic diseases are associated with changes in the sequence of particular genes. We describe here a rapid and highly efficient assay for the detection of point mutation. This method is a combination of isothermal rolling circle amplification (RCA) and high sensitive electrochemluminescence (ECL) detection. In the design, a circular template generated by ligation upon the recognition of a point mutation on DNA targets was amplified isothermally by the Phi29 polymerase using a biotinylated primer. The elongation products were hybridized with tris (bipyridine) ruthenium (TBR)-tagged probes and detected in a magnetic bead based ECL platform, indicating the mutation occurrence. P53 was chosen as a model for the identification of this method. The method allowed sensitive determination of the P53 mutation from wild-type and mutant samples. The main advantage of RCA-ECL is that it can be performed under isothermal conditions and avoids the generation of false-positive results. Furthermore, ECL provides a faster, more sensitive, and economical option to currently available electrophoresis-based methods.

Molecular Dynamic Simulation Insights into the Normal State and Restoration of p53 Function

PubMed Central

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

2012-01-01

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

miR-300 promotes proliferation and EMT-mediated colorectal cancer migration and invasion by targeting p53.

PubMed

Wang, Lin; Yu, Peiwu

2016-12-01

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

Leprosy Drug Resistance Surveillance in Colombia: The Experience of a Sentinel Country

PubMed Central

Beltrán-Alzate, Camilo; López Díaz, Fernando; Romero-Montoya, Marcela; Sakamuri, Rama; Li, Wei; Kimura, Miyako; Brennan, Patrick

2016-01-01

An active search for Mycobacterium leprae drug resistance was carried out, 243 multibacillary patients from endemic regions of Colombia were included from 2004 to 2013 in a surveillance program. This program was a World Health Organization initiative for drug resistance surveillance in leprosy, where Colombia is a sentinel country. M. leprae DNA from slit skin smear and/or skin biopsy samples was amplified and sequenced to identify mutations in the drug resistance determining region (DRDR) in rpoB, folP1, gyrA, and gyrB, the genes responsible for rifampicin, dapsone and ofloxacin drug-resistance, respectively. Three isolates exhibited mutations in the DRDR rpoB gene (Asp441Tyr, Ser456Leu, Ser458Met), two in the DRDR folP1 gene (Thr53Ala, Pro55Leu), and one isolate exhibited mutations in both DRDR rpoB (Ser456Met) and DRDR folP1 (Pro55Leu), suggesting multidrug resistance. One isolate had a double mutation in folP1 (Thr53Ala and Thr88Pro). Also, we detected mutations outside of DRDR that required in vivo evaluation of their association or not with drug resistance: rpoB Arg505Trp, folP1 Asp91His, Arg94Trp, and Thr88Pro, and gyrA Ala107Leu. Seventy percent of M. leprae mutations were related to drug resistance and were isolated from relapsed patients; the likelihood of relapse was significantly associated with the presence of confirmed resistance mutations (OR range 20.1–88.7, p < 0.05). Five of these relapsed patients received dapsone monotherapy as a primary treatment. In summary, the current study calls attention to M. leprae resistance in Colombia, especially the significant association between confirmed resistance mutations and relapse in leprosy patients. A high frequency of DRDR mutations for rifampicin was seen in a region where dapsone monotherapy was used extensively. PMID:27706165

Mutation at p53 serine 389 does not rescue the embryonic lethality in mdm2 or mdm4 null mice.

PubMed

Iwakuma, Tomoo; Parant, John M; Fasulo, Mark; Zwart, Edwin; Jacks, Tyler; de Vries, Annemieke; Lozano, Guillermina

2004-10-07

Mdm2 and its homolog Mdm4 inhibit the function of the tumor suppressor p53. Targeted disruption of either mdm2 or mdm4 genes in mice results in embryonic lethality that is completely rescued by concomitant deletion of p53, suggesting that deletion of negative regulators of p53 results in a constitutively active p53. Thus, these mouse models offer a unique in vivo system to assay the functional significance of different p53 modifications. Phosphorylation of serine 389 in murine p53 occurs specifically after ultraviolet-light-induced DNA damage, and phosphorylation of this site enhances p53 activity both in vitro and in vivo. Recently, mice with a serine to alanine substitution at serine 389 (p53S389A) in the endogenous p53 locus were generated. To examine the in vivo significance of serine 389 phosphorylation during embryogenesis, we crossed these mutant mice to mice lacking mdm2 or mdm4. The p53S389A allele did not alter the embryonic lethality of mdm2 or mdm4. Additional crosses to assay the effect of one p53S389A allele with a p53 null allele also did not rescue the lethal phenotypes. In conclusion, the phenotypes due to loss of mdm2 or mdm4 were not even partially rescued by p53S389A, suggesting that p53S389A is functionally wild type during embryogenesis.

Immunohistochemical expression of p53 proteins in Wilms' tumour: a possible association with the histological prognostic parameter of anaplasia.

PubMed

Cheah, P L; Looi, L M; Chan, L L

1996-01-01

Wilms' tumour (nephroblastoma) has been associated with chromosomal abnormalities at the 11p13, 11p15 and 16q regions. A study into the possibility of mutations occurring within p53, the ubiquitous adult tumour suppressor gene, in Wilms' tumour was carried out. Thirty-eight cases were studied. Of these 36 were categorised into the favourable histology group and two into the unfavourable histology group based on the National Wilms' Tumour Study criteria. Archival formalin-fixed, paraffin-embedded tissue sections from each case were stained with a polyclonal (AB565:Chemicon) and a monoclonal (DO7:Dako) antibody raised against p53 protein using a peroxidase-labelled streptavidin biotin kit (Dako). 'Cure' (disease-free survival of 60 months or longer) was documented in 39% of cases with favourable histology tumours. Eleven percent in this group succumbed to the disease. Both cases with unfavourable histology died. Four out of 36 (11%) tumours with favourable histology demonstrated weak to moderate staining with both AB565 and DO7 in more than 75% of tumour cells. In contrast, p53 protein expression in unfavourable histology tumours was significantly increased compared with the favourable histology group (P = 0.021) with both cases demonstrating immunopositivity in > 75% of tumour cells when stained with AB565 and DO7. The intensity of staining ranged from moderate to strong in both cases. It appears from this preliminary study that the immunohistochemical expression of p53 protein in Wilms' tumour, presumably a result of mutation in the p53 tumour suppressor gene, correlates with histological classification, histological categorisation being one of the useful features in the prognostic assessment of Wilms' tumours.

A Sensitive and Specific Diagnostic Panel to Distinguish Diffuse Astrocytoma from Astrocytosis: Chromosome 7 Gain with Mutant Isocitrate Dehydrogenase 1 and p53

PubMed Central

Camelo-Piragua, Sandra; Jansen, Michael; Ganguly, Aniruddha; Kim, J. ChulMin; Cosper, Arjola K.; Dias-Santagata, Dora; Nutt, Catherine L.; Iafrate, A. John; Louis, David N.

2011-01-01

One of the major challenges of surgical neuropathology is the distinction of diffuse astrocytoma (World Health Organization [WHO] grade II) from astrocytosis. The most commonly used ancillary tool to solve this problem is p53 immunohistochemistry (IHC), but this is neither sensitive nor specific. Isocitrate dehydrogenase 1 (IDH1) mutations are common in lower grade gliomas, with most causing a specific amino acid change (R132H) that can be detected with a monoclonal antibody. IDH2 mutations are rare, but also occur in gliomas. In addition, gains of chromosome 7 are common in gliomas. In this study we assessed the status of p53, IDH1/2 and chromosome 7 to determine the most useful panel to distinguish astrocytoma from astrocytosis. We studied biopsy specimens from 21 WHO grade II diffuse astrocytomas and 20 reactive conditions. The single most sensitive test to identify astrocytoma is fluorescence in situ hybridization (FISH) for chromosome 7 gain (76.2%). The combination of p53 and mutant IDH1 IHC provides a higher sensitivity (71.4%) than either test alone (47.8%); this combination offers a practical initial approach for the surgical pathologist. The best overall sensitivity (95%) is achieved when FISH for chromosome 7 gain is added to the p53-mutant IDH1 IHC panel. PMID:21343879

Segregation of non-p.R132H mutations in IDH1 in distinct molecular subtypes of glioma.

PubMed

Gravendeel, Lonneke A M; Kloosterhof, Nanne K; Bralten, Linda B C; van Marion, Ronald; Dubbink, Hendrikus Jan; Dinjens, Winand; Bleeker, Fonnet E; Hoogenraad, Casper C; Michiels, Erna; Kros, Johan M; van den Bent, Martin; Smitt, Peter A E Sillevis; French, Pim J

2010-03-01

Mutations in the gene encoding the isocitrate dehydrogenase 1 gene (IDH1) occur at a high frequency (up to 80%) in many different subtypes of glioma. In this study, we have screened for IDH1 mutations in a cohort of 496 gliomas. IDH1 mutations were most frequently observed in low grade gliomas with c.395G>A (p.R132H) representing >90% of all IDH1 mutations. Interestingly, non-p.R132H mutations segregate in distinct histological and molecular subtypes of glioma. Histologically, they occur sporadically in classic oligodendrogliomas and at significantly higher frequency in other grade II and III gliomas. Genetically, non-p.R132H mutations occur in tumors with TP53 mutation, are virtually absent in tumors with loss of heterozygosity on 1p and 19q and accumulate in distinct (gene-expression profiling based) intrinsic molecular subtypes. The IDH1 mutation type does not affect patient survival. Our results were validated on an independent sample cohort, indicating that the IDH1 mutation spectrum may aid glioma subtype classification. Functional differences between p.R132H and non-p.R132H mutated IDH1 may explain the segregation in distinct glioma subtypes. (c) 2010 Wiley-Liss, Inc.

RAS mutation status predicts survival and patterns of recurrence in patients undergoing hepatectomy for colorectal liver metastases.

PubMed

Vauthey, Jean-Nicolas; Zimmitti, Giuseppe; Kopetz, Scott E; Shindoh, Junichi; Chen, Su S; Andreou, Andreas; Curley, Steven A; Aloia, Thomas A; Maru, Dipen M

2013-10-01

To determine the impact of RAS mutation status on survival and patterns of recurrence in patients undergoing curative resection of colorectal liver metastases (CLM) after preoperative modern chemotherapy. RAS mutation has been reported to be associated with aggressive tumor biology. However, the effect of RAS mutation on survival and patterns of recurrence after resection of CLM remains unclear. Somatic mutations were analyzed using mass spectroscopy in 193 patients who underwent single-regimen modern chemotherapy before resection of CLM. The relationship between RAS mutation status and survival outcomes was investigated. Detected somatic mutations included RAS (KRAS/NRAS) in 34 (18%), PIK3CA in 13 (7%), and BRAF in 2 (1%) patients. At a median follow-up of 33 months, 3-year overall survival (OS) rates were 81% in patients with wild-type versus 52.2% in patients with mutant RAS (P = 0.002); 3-year recurrence-free survival (RFS) rates were 33.5% with wild-type versus 13.5% with mutant RAS (P = 0.001). Liver and lung recurrences were observed in 89 and 83 patients, respectively. Patients with RAS mutation had a lower 3-year lung RFS rate (34.6% vs 59.3%, P < 0.001) but not a lower 3-year liver RFS rate (43.8% vs 50.2%, P = 0.181). In multivariate analyses, RAS mutation predicted worse OS [hazard ratio (HR) = 2.3, P = 0.002), overall RFS (HR = 1.9, P = 0.005), and lung RFS (HR = 2.0, P = 0.01), but not liver RFS (P = 0.181). RAS mutation predicts early lung recurrence and worse survival after curative resection of CLM. This information may be used to individualize systemic and local tumor-directed therapies and follow-up strategies.

RAS mutation status predicts survival and patterns of recurrence in patients undergoing hepatectomy for colorectal liver metastases

PubMed Central

Vauthey, Jean-Nicolas; Zimmitti, Giuseppe; Kopetz, Scott E.; Shindoh, Junichi; Chen, Su S.; Andreou, Andreas; Curley, Steven A.; Aloia, Thomas A.; Maru, Dipen M.

2013-01-01

Objective To determine the impact of RAS mutation status on survival and patterns of recurrence in patients undergoing curative resection of colorectal liver metastases (CLM) after preoperative modern chemotherapy. Summary Background Data RAS mutation has been reported to be associated with aggressive tumor biology. However, the effect of RAS mutation on survival and patterns of recurrence after resection of CLM remains unclear. Methods Somatic mutations were analyzed using mass spectroscopy in 193 patients who underwent single-regimen modern chemotherapy before resection of CLM. The relationship between RAS mutation status and survival outcomes was investigated. Results Detected somatic mutations included RAS (KRAS/NRAS) in 34 patients (18%), PIK3CA in 13 (7%), and BRAF in 2 (1%). At a median follow-up of 33 months, 3-year overall survival (OS) rates were 81% in patients with wild-type vs 52.2% in patients with mutant RAS (P=0.002); 3-year recurrence-free survival (RFS) rates were 33.5% with wild-type vs 13.5% with mutant RAS (P=0.001). Liver and lung recurrences were observed in 89 and 83 patients, respectively. Patients with RAS mutation had a lower 3-year lung RFS rate (34.6% vs 59.3%, P<0.001), but not a lower 3-year liver RFS rate (43.8% vs 50.2%, P=0.181). In multivariate analyses, RAS mutation predicted worse OS (hazard ratio [HR] 2.3, P=0.002), overall RFS (HR 1.9, P=0.005), and lung RFS (HR 2.0, P=0.01), but not liver RFS (P=0.181). Conclusions RAS mutation predicts early lung recurrence and worse survival after curative resection of CLM. This information may be used to individualize systemic and local tumor-directed therapies and follow-up strategies. PMID:24018645

[Clinical significance and mechanism of upregulation of PI3Kp110α in non-small cell lung carcinoma].

PubMed

Xiong, Y; Qu, L L; Li, D; Wang, Y; Li, T

2017-10-23

Objective: To investigate the clinical significance and mechanism of upregulation of phosphoinositide 3-kinase p110α(PI3Kp110α)in non-small cell lung carcinoma (NSCLC). Methods: Expressions of PI3Kp110α and other components in PI3K signaling pathway (including phospho-Akt (p-Akt, Ser 473), MET, ROS1, HER-2, ALK, total EGFR and mutant EGFR) and p53 (the transcription factor of PIK3CA) mutation in NSCLC were detected by immunohistochemistry. The relationships between PI3Kp110α expression and clinicopathological characteristics, expressions of other proteins in PI3K pathway and p53 mutation were analyzed. Results: In 170 NSCLC patients, 72 cases (42.4%) showed lower expression and 98 cases (57.6%) showed higher expression of PI3Kp110α. Upregulation of PI3Kp110α was not significantly associated with gender, age, T stage and pathologic grade ( P >0.05). While upregulation of PI3Kp110α was significantly associated with smoking status of patients, pathologic classification, N stage, TNM stage and Ki-67 index ( P <0.05). Expression of PI3Kp110α was positively correlated with expressions of MET ( P <0.05) and mutant EGFR ( P =0.018), while not significantly related with expressions of p-Akt(Ser473), HER-2, ALK, ROS1, total EGFR or p53 mutation ( P >0.05). Conclusions: Upregulation of PI3Kp110α is closely related with tumorigenesis of non-smoking lung adenocarcinoma. MET overexpression and EGFR mutation may be crucial to upregulate expression of PI3Kp110α in NSCLC. Overexpression of PI3Kp110α may inhibit tumor cell proliferation in NSCLC through a different pathway other than classical PI3K pathway. Upregulation of PI3Kp110α may predict favorable prognosis of NSCLC patients.

Comparison of kinetics, toxicity, oligomers formation and membrane binding capacity of α-synuclein familial mutations at A53 site including newly discovered A53V mutation.

PubMed

Mohite, Ganesh M; Kumar, Rakesh; Panigrahi, Rajlaxmi; Navalkar, Ambuja; Singh, Nitu; Datta, Debalina; Mehra, Surabhi; Ray, Soumik; Gadhe, Laxmikant G; Das, Subhadeep; Singh, Namrata; Chatterjee, Debdeep; Kumar, Ashutosh; Maji, Samir K

2018-05-17

The involvement of α-synuclein (α-Syn) amyloid formation in Parkinson's disease (PD) pathogenesis is supported by the discovery of α-Syn gene (SNCA) mutations linked with familial PD, which are known to modulate the oligomerization and aggregation of α-Syn. Recently, the A53V mutation has been discovered, which leads to the late-onset PD. In the present study, we characterized for the first time the biophysical properties including the aggregation propensities, toxicity of aggregated species and membrane binding capability of A53V along with all familial mutations at A53 position. Present data suggest that A53V accelerate fibrillation of α-Syn without affecting the overall morphology and cytotoxicity of fibrils compared to wild-type protein. The aggregation propensity for A53 mutants is found to be; A53T>A53V>WT>A53E. Further, time course aggregation study reveals that A53V mutant promotes early oligomerization similar to A53T mutation. It promotes the highest amount of oligomer formation immediate after dissolution, which are cytotoxic. Although in the presence of membrane-mimicking environments, A53V mutation showed similar extent of helix-induction capacity as of WT protein, however, it exhibited lesser binding to lipid vesicle. The NMR study revealed unique chemical shift perturbation by A53V mutation com-pared to other mutations at A53 site. The present study might help to establish the disease-causing mechanism of A53V in PD pathology.

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

Pharmacological activation of a novel p53-dependent S-phase checkpoint involving CHK-1

PubMed Central

Ahmed, A; Yang, J; Maya-Mendoza, A; Jackson, D A; Ashcroft, M

2011-01-01

We have recently shown that induction of the p53 tumour suppressor protein by the small-molecule RITA (reactivation of p53 and induction of tumour cell apoptosis; 2,5-bis(5-hydroxymethyl-2-thienyl)furan) inhibits hypoxia-inducible factor-1α and vascular endothelial growth factor expression in vivo and induces p53-dependent tumour cell apoptosis in normoxia and hypoxia. Here, we demonstrate that RITA activates the canonical ataxia telangiectasia mutated/ataxia telangiectasia and Rad3-related DNA damage response pathway. Interestingly, phosphorylation of checkpoint kinase (CHK)-1 induced in response to RITA was influenced by p53 status. We found that induction of p53, phosphorylated CHK-1 and γH2AX proteins was significantly increased in S-phase. Furthermore, we found that RITA stalled replication fork elongation, prolonged S-phase progression and induced DNA damage in p53 positive cells. Although CHK-1 knockdown did not significantly affect p53-dependent DNA damage or apoptosis induced by RITA, it did block the ability for DNA integrity to be maintained during the immediate response to RITA. These data reveal the existence of a novel p53-dependent S-phase DNA maintenance checkpoint involving CHK-1. PMID:21593792

Phosphorylation of p53 at serine 15 in A549 pulmonary epithelial cells exposed to vanadate: Involvement of ATM pathway

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

Suzuki, Katsura; Inageda, Kiyoshi; Nishitai, Gen

2007-04-01

When A549 cells were exposed to sodium metavanadate (NaVO{sub 3}), the pentavalent species of vanadium (vanadate), phosphorylation of p53 protein at Ser15 was found in a time (8-48 h)- and dose (10-200 {mu}M)-dependent manner. After the incubation with 50 or 100 {mu}M NaVO{sub 3} for 48 h, accumulation of p53 protein was accompanied with Ser15 phosphorylation. Among serines in p53 protein immunoprecipitated from A549 cells treated with 100 {mu}M NaVO{sub 3} for 48 h, only Ser15 was markedly phosphorylated. Treatment with other vanadate compounds, sodium orthovanadate (Na{sub 3}VO{sub 4}) and ammonium metavanadate (NH{sub 4}VO{sub 3}), also induced Ser15 phosphorylation andmore » accumulation of p53 protein. While phosphorylation of extracellular signal-regulated protein kinase (ERK) was found in cells treated with NaVO{sub 3}, treatment with U0126 did not suppress Ser15 phosphorylation. On the other hand, treatment with wortmannin or caffeine, the inhibitors to phosphatidylinositol 3-kinase related kinases (PIKKs), suppressed both NaVO{sub 3}-induced Ser15 phosphorylation and accumulation of p53 protein. The silencing of ataxia telangiectasia mutated (ATM) expression using short-interference RNA resulted in the marked suppression of Ser15 phosphorylation in A549 cells exposed to NaVO{sub 3}. However, treatment with antioxidants such as catalase and N-acetylcysteine did not suppress NaVO{sub 3}-induced Ser15 phosphorylation. Transcriptional activation of p53 and DNA fragmentation in A549 cells treated with NaVO{sub 3} were suppressed only slightly by S15A mutation, suggesting that Ser15 phosphorylation is not essential for these responses. The present results showed that vanadate induces the phosphorylation of p53 at Ser15 depending on ATM, one of the members of PIKK family, in this human pulmonary epithelial cell line.« less

Interaction between the Cockayne syndrome B and p53 proteins: implications for aging

PubMed Central

Frontini, Mattia; Proietti-De-Santis, Luca

2012-01-01

The CSB protein plays a role in the transcription coupled repair (TCR) branch of the nucleotide excision repair pathway. CSB is very often found mutated in Cockayne syndrome, a segmental progeroid genetic disease characterized by organ degeneration and growth failure. The tumor suppressor p53 plays a pivotal role in triggering senescence and apoptosis and suppressing tumorigenesis. Although p53 is very important to avoid cancer, its excessive activity can be detrimental for the lifespan of the organism. This is why a network of positive and negative feedback loops, which most likely evolved to fine-tune the activity of this tumor suppressor, modulate its induction and activation. Accordingly, an unbalanced p53 activity gives rise to premature aging or cancer. The physical interaction between CSB and p53 proteins has been known for more than a decade but, despite several hypotheses, nobody has been able to show the functional consequences of this interaction. In this review we resume recent advances towards a more comprehensive understanding of the critical role of this interaction in modulating p53's levels and activity, therefore helping the system find a reasonable equilibrium between the beneficial and the detrimental effects of its activity. This crosstalk re-establishes the physiological balance towards cell proliferation and survival instead of towards cell death, after stressors of a broad nature. Accordingly, cells bearing mutations in the csb gene are unable to re-establish this physiological balance and to properly respond to some stress stimuli and undergo massive apoptosis. PMID:22383384

Neurofibromin Deficiency-Associated Transcriptional Dysregulation Suggests a Novel Therapy for Tibial Pseudoarthrosis in NF1

PubMed Central

Paria, Nandina; Cho, Tae-Joon; Choi, In Ho; Kamiya, Nobuhiro; Kayembe, Kay; Mao, Rong; Margraf, Rebecca L.; Obermosser, Gerlinde; Oxendine, Ila; Sant, David W.; Song, Mi Hyun; Stevenson, David A.; Viskochil, David H.; Wise, Carol A.; Kim, Harry K.W.; Rios, Jonathan J

2014-01-01

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease caused by mutations in NF1. Among the earliest manifestations is tibial pseudoarthrosis and persistent nonunion after fracture. To further understand the pathogenesis of pseudoarthrosis and the underlying bone remodeling defect, pseudoarthrosis tissue and cells cultured from surgically resected pseudoarthrosis tissue from NF1 individuals were analyzed using whole-exome and whole-transcriptome sequencing as well as genomewide microarray analysis. Genomewide analysis identified multiple genetic mechanisms resulting in somatic bi-allelic NF1 inactivation; no other genes with recurring somatic mutations were identified. Gene expression profiling identified dysregulated pathways associated with neurofibromin deficiency, including phosphoinosital-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways. Unlike aggressive NF1-associated malignancies, tibial pseudoarthrosis tissue does not harbor a high frequency of somatic mutations in oncogenes or other tumor-suppressor genes, such as p53. However, gene expression profiling indicates pseudoarthrosis tissue has a tumor-promoting transcriptional pattern, despite lacking tumorigenic somatic mutations. Significant over-expression of specific cancer-associated genes in pseudoarthrosis highlights a potential for receptor tyrosine kinase inhibitors to target neurofibromin-deficient pseudoarthrosis and promote proper bone remodeling and fracture healing. PMID:24932921

Comprehensive mutation analysis of PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1 genes is suggestive of a non- neoplastic nature of phenytoin induced gingival overgrowth.

PubMed

Swamikannu, Bhuminathan; Kumar, Kishore S; Jayesh, Raghavendra S; Rajendran, Senthilnathan; Muthupalani, Rajendran Shanmugam; Ramanathan, Arvind

2013-01-01

Dilantin sodium (phenytoin) is an antiepileptic drug, which is routinely used to control generalized tonic clonic seizure and partial seizure episodes. A few case reports of oral squamous cell carcinomas arising from regions of phenytoin induced gingival overgrowth (GO), and overexpression of mitogenic factors and p53 have presented this condition as a pathology with potential to transform into malignancy. We recently investigated the genetic status of p53 and H-ras, which are known to be frequently mutated in Indian oral carcinomas in GO tissues and found them to only contain wild type sequences, which suggested a non-neoplastic nature of phenytoin induced GO. However, besides p53 and H-ras, other oncogenes and tumor suppressors such as PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1, are frequently altered in oral squamous cell carcinoma, and hence are required to be analyzed in phenytoin induced GO tissues to be affirmative of its non-neoplastic nature. 100ng of chromosomal DNA isolated from twenty gingival overgrowth tissues were amplified with primers for exons 9 and 20 of PIK3CA, exons 1α, 1β and 2 of p16INK4a and p14ARF, and exon 2 of p21Waf1/Cip1, in independent reactions. PCR amplicons were subsequently gel purified and eluted products were sequenced. Sequencing analysis of the twenty samples of phenytoin induced gingival growth showed no mutations in the analyzed exons of PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1. The present data indicate that the mutational alterations of genes, PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1 that are frequently mutated in oral squamous cell carcinomas are rare in phenytoin induced gingival growth. Thus the findings provide further evidence that phenytoin induced gingival overgrowth as a non-neoplastic lesion, which may be considered as clinically significant given the fact that the epileptic patients are routinely administered with phenytoin for the rest of their lives to control seizure episodes.

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

Alexandrov, L. B.

All cancers originate from a single cell that starts to behave abnormally, to divide uncontrollably, and, eventually, to invade adjacent tissues (1). The aberrant behavior of this single cell is due to somatic mutations—changes in the genomic DNA produced by the activity of different mutational processes (1). These various mutational processes include exposure to exogenous or endogenous mutagens, abnormal DNA editing, the incomplete fidelity of DNA polymerases, and failure of DNA repair mechanisms (2). Early studies that sequenced TP53, the most commonly mutated gene in human cancer, provided evidence that mutational processes leave distinct imprints of somatic mutations on themore » genome of a cancer cell (3). For example, C:G>A:T transversions predominate in smoking-associated lung cancer, whereas C:G>T:A transitions occurring mainly at dipyrimidines and CC:GG>TT:AA double-nucleotide substitutions are common in ultraviolet light–associated skin cancers. Moreover, these patterns of mutations matched the ones induced experimentally by tobacco mutagens and ultraviolet light, respectively, the major, known, exogenous carcinogenic influences in these cancer types, and demonstrated that examining patterns of mutations in cancer genomes can yield information about the mutational processes that cause human cancer (4).« less

Understanding the origins of human cancer

DOE PAGES

Alexandrov, L. B.

2015-12-04

All cancers originate from a single cell that starts to behave abnormally, to divide uncontrollably, and, eventually, to invade adjacent tissues (1). The aberrant behavior of this single cell is due to somatic mutations—changes in the genomic DNA produced by the activity of different mutational processes (1). These various mutational processes include exposure to exogenous or endogenous mutagens, abnormal DNA editing, the incomplete fidelity of DNA polymerases, and failure of DNA repair mechanisms (2). Early studies that sequenced TP53, the most commonly mutated gene in human cancer, provided evidence that mutational processes leave distinct imprints of somatic mutations on themore » genome of a cancer cell (3). For example, C:G>A:T transversions predominate in smoking-associated lung cancer, whereas C:G>T:A transitions occurring mainly at dipyrimidines and CC:GG>TT:AA double-nucleotide substitutions are common in ultraviolet light–associated skin cancers. Moreover, these patterns of mutations matched the ones induced experimentally by tobacco mutagens and ultraviolet light, respectively, the major, known, exogenous carcinogenic influences in these cancer types, and demonstrated that examining patterns of mutations in cancer genomes can yield information about the mutational processes that cause human cancer (4).« less

Correlation of Merkel cell polyomavirus positivity with PDGFRα mutations and survivin expression in Merkel cell carcinoma.

PubMed

Batinica, M; Akgül, B; Silling, S; Mauch, C; Zigrino, P

2015-07-01

Merkel cell carcinoma (MCC) is a neuroendocrine cancer of the skin postulated to originate through Merkel cell polyomavirus (MCPyV) oncogenesis and/or by mutations in molecules implicated in the regulation of cell growth and survival. Despite the fact that MCPvV is detected more broadly within the population, only a part of the infected people also develop MCC. It is thus conceivable that together, virus and for example mutations, are necessary for disease development. However, apart from a correlation between MCPyV positivity or mutations and MCC development, less is known about the association of these factors with progressive disease. To analyze MCPyV positivity, load and integration in MCC as well as presence of mutations in PDGFRα and TP53 genes and correlate these with clinical features and disease progression to identify features with prognostic value for clinical progression. This is a study on a MCC population group of 64 patients. MCPyV positivity, load and integration in parallel to mutations in the PDGFRα and TP53 were analyzed on genomic DNA from MCC specimens. In addition, expression of PDGFRα, survivin and p53 proteins was analyzed by immunodetection in tissues specimens. All these parameters were analyzed as function of patient's disease progression status. 83% of MCCs were positive for the MCPyV and among these 36% also displayed virus-T integration. Viral load ranged from 0.006 to 943 viral DNA copies/β-globin gene and was highest in patients with progressive disease. We detected more than one mutation within the PDGFRα gene and identified two new SNPs in 36% of MCC patients, whereas no mutations were found in TP53 gene. Survivin was expressed in 78% of specimens. We could not correlate either mutations in PDGFR or expression of PDGFR, p53 and surviving either to the disease progression or to the MCPyV positivity. In conclusion, our data indicate that the viral positivity when associated with high viral load, correlates with poor disease outcome. Frequent mutations in the PDGFRα gene and high survivin expression were found in MCC independent of the viral positivity. These data suggest that these three factors independently contribute to Merkel cell carcinoma development and that only the viral load can be used as indicator of disease progression in virus positive patients. Copyright © 2015 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

TP53, STK11 and EGFR Mutations Predict Tumor Immune Profile and the Response to anti-PD-1 in Lung Adenocarcinoma.

PubMed

Biton, Jerome; Mansuet-Lupo, Audrey; Pécuchet, Nicolas; Alifano, Marco; Ouakrim, Hanane; Arrondeau, Jennifer; Boudou-Rouquette, Pascaline; Goldwasser, Francois; Leroy, Karen; Goc, Jeremy; Wislez, Marie; Germain, Claire; Laurent-Puig, Pierre; Dieu-Nosjean, Marie-Caroline; Cremer, Isabelle; Herbst, Ronald; Blons, Hélène F; Damotte, Diane

2018-05-15

By unlocking anti-tumor immunity, antibodies targeting programmed cell death 1 (PD-1) exhibit impressive clinical results in non-small cell lung cancer, underlining the strong interactions between tumor and immune cells. However, factors that can robustly predict long-lasting responses are still needed. We performed in depth immune profiling of lung adenocarcinoma using an integrative analysis based on immunohistochemistry, flow-cytometry and transcriptomic data. Tumor mutational status was investigated using next-generation sequencing. The response to PD-1 blockers was analyzed from a prospective cohort according to tumor mutational profiles and to PD-L1 expression, and a public clinical database was used to validate the results obtained. We showed that distinct combinations of STK11 , EGFR and TP53 mutations, were major determinants of the tumor immune profile (TIP) and of the expression of PD-L1 by malignant cells. Indeed, the presence of TP53 mutations without co-occurring STK11 or EGFR alterations ( TP53 -mut/ STK11 - EGFR -WT), independently of KRAS mutations, identified the group of tumors with the highest CD8 T cell density and PD-L1 expression. In this tumor subtype, pathways related to T cell chemotaxis, immune cell cytotoxicity, and antigen processing were up-regulated. Finally, a prolonged progression-free survival (PFS: HR=0.32; 95% CI, 0.16-0.63, p <0.001) was observed in anti-PD-1 treated patients harboring TP53 -mut/ STK11 - EGFR -WT tumors. This clinical benefit was even more remarkable in patients with associated strong PD-L1 expression. Our study reveals that different combinations of TP53 , EGFR and STK11 mutations , together with PD-L1 expression by tumor cells, represent robust parameters to identify best responders to PD-1 blockade. Copyright ©2018, American Association for Cancer Research.

Small cell and large cell neuroendocrine carcinomas of the pancreas are genetically similar and distinct from well-differentiated pancreatic neuroendocrine tumors.

PubMed

Yachida, Shinichi; Vakiani, Efsevia; White, Catherine M; Zhong, Yi; Saunders, Tyler; Morgan, Richard; de Wilde, Roeland F; Maitra, Anirban; Hicks, Jessica; Demarzo, Angelo M; Shi, Chanjuan; Sharma, Rajni; Laheru, Daniel; Edil, Barish H; Wolfgang, Christopher L; Schulick, Richard D; Hruban, Ralph H; Tang, Laura H; Klimstra, David S; Iacobuzio-Donahue, Christine A

2012-02-01

Poorly differentiated neuroendocrine carcinomas (NECs) of the pancreas are rare malignant neoplasms with a poor prognosis. The aim of this study was to determine the clinicopathologic and genetic features of poorly differentiated NECs and compare them with other types of pancreatic neoplasms. We investigated alterations of KRAS, CDKN2A/p16, TP53, SMAD4/DPC4, DAXX, ATRX, PTEN, Bcl2, and RB1 by immunohistochemistry and/or targeted exomic sequencing in surgically resected specimens of 9 small cell NECs, 10 large cell NECs, and 11 well-differentiated neuroendocrine tumors (PanNETs) of the pancreas. Abnormal immunolabeling patterns of p53 and Rb were frequent (p53, 18 of 19, 95%; Rb, 14 of 19, 74%) in both small cell and large cell NECs, whereas Smad4/Dpc4, DAXX, and ATRX labeling was intact in virtually all of these same carcinomas. Abnormal immunolabeling of p53 and Rb proteins correlated with intragenic mutations in the TP53 and RB1 genes. In contrast, DAXX and ATRX labeling was lost in 45% of PanNETs, whereas p53 and Rb immunolabeling was intact in these same cases. Overexpression of Bcl-2 protein was observed in all 9 small cell NECs (100%) and in 5 of 10 (50%) large cell NECs compared with only 2 of 11 (18%) PanNETs. Bcl-2 overexpression was significantly correlated with higher mitotic rate and Ki67 labeling index in neoplasms in which it was present. Small cell NECs are genetically similar to large cell NECs, and these genetic changes are distinct from those reported in PanNETs. The finding of Bcl-2 overexpression in poorly differentiated NECs, particularly small cell NEC, suggests that Bcl-2 antagonists/inhibitors may be a viable treatment option for these patients.

Multiplex Detection of Rare Mutations by Picoliter Droplet Based Digital PCR: Sensitivity and Specificity Considerations.

PubMed

Zonta, Eleonora; Garlan, Fanny; Pécuchet, Nicolas; Perez-Toralla, Karla; Caen, Ouriel; Milbury, Coren; Didelot, Audrey; Fabre, Elizabeth; Blons, Hélène; Laurent-Puig, Pierre; Taly, Valérie

2016-01-01

In cancer research, the accuracy of the technology used for biomarkers detection is remarkably important. In this context, digital PCR represents a highly sensitive and reproducible method that could serve as an appropriate tool for tumor mutational status analysis. In particular, droplet-based digital PCR approaches have been developed for detection of tumor-specific mutated alleles within plasmatic circulating DNA. Such an approach calls for the development and validation of a very significant quantity of assays, which can be extremely costly and time consuming. Herein, we evaluated assays for the detection and quantification of various mutations occurring in three genes often misregulated in cancers: the epidermal growth factor receptor (EGFR), the v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) and the Tumoral Protein p53 (TP53) genes. In particular, commercial competitive allele-specific TaqMan® PCR (castPCR™) technology, as well as TaqMan® and ZEN™ assays, have been evaluated for EGFR p.L858R, p.T790M, p.L861Q point mutations and in-frame deletions Del19. Specificity and sensitivity have been determined on cell lines DNA, plasmatic circulating DNA of lung cancer patients or Horizon Diagnostics Reference Standards. To show the multiplexing capabilities of this technology, several multiplex panels for EGFR (several three- and four-plexes) have been developed, offering new "ready-to-use" tests for lung cancer patients.

Controlling aggregation propensity in A53T mutant of alpha-synuclein causing Parkinson's disease

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

Kumar, Sonu; Sarkar, Anita; Sundar, Durai, E-mail: sundar@dbeb.iitd.ac.in

2009-09-18

Understanding {alpha}-synuclein in terms of fibrillization, aggregation, solubility and stability is fundamental in Parkinson's disease (PD). The three familial mutations, namely, A30P, E46K and A53T cause PD because the hydrophobic regions in {alpha}-synuclein acquire {beta}-sheet configuration, and have a propensity to fibrillize and form amyloids that cause cytotoxicity and neurodegeneration. On simulating the native form and mutants (A30P, E46K and A53T) of {alpha}-synuclein in water solvent, clear deviations are observed in comparison to the all-helical 1XQ8 PDB structure. We have identified two crucial residues, {sup 40}Val and {sup 74}Val, which play key roles in {beta}-sheet aggregation in the hydrophobic regionsmore » 36-41 and 68-78, respectively, leading to fibrillization and amyloidosis in familial (A53T) PD. We have also identified V40D{sub V}74D, a double mutant of A53T (the most amyloidogenic mutant). The simultaneous introduction of these two mutations in A53T nearly ends its aggregation propensity, increases its solubility and positively enhances its thermodynamic stability.« less

Identification of a small molecule that overcomes HdmX-mediated suppression of p53

PubMed Central

Chakrabarti, Amit; Karan, Sukanya; Liu, Zhigang; Xia, Zhiqiang; Gundluru, Mahesh; Moreton, Stephen; Saunthararajah, Yogen; Jackson, Mark W; Agarwal, Mukesh K; Wald, David N

2016-01-01

Inactivation of the p53 tumor suppressor by mutation or overexpression of negative regulators occurs frequently in cancer. Since p53 plays a key role in regulating proliferation or apoptosis in response to DNA damaging chemotherapies, strategies aimed at reactivating p53 are increasingly being sought. Strategies to reactivate wild-type p53 include the use of small molecules capable of releasing wild-type p53 from key, cellular negative regulators, such as Hdm2 and HdmX. Derivatives of the Hdm2 antagonist Nutlin-3 are in clinical trials. However, Nutlin-3 specifically disrupts Hdm2-p53, leaving tumors harboring high levels of HdmX resistant to Nutlin-3 treatment. Here we identify CTX1, a novel small molecule that overcomes HdmX-mediated p53 repression. CTX1 binds directly to HdmX to prevent p53-HdmX complex formation, resulting in the rapidly induction of p53 in a DNA damage-independent manner. Treatment of a panel of cancer cells with CTX1 induced apoptosis or suppressed proliferation and importantly, CTX1 demonstrates promising activity as a single agent in a mouse model of circulating primary human leukemia. CTX1 is a small molecule HdmX inhibitor that demonstrates promise as a cancer therapeutic candidate. PMID:26883273

Cell-free DNA as a molecular tool for monitoring disease progression and response to therapy in breast cancer patients.

PubMed

Liang, Diana H; Ensor, Joe E; Liu, Zhe-Bin; Patel, Asmita; Patel, Tejal A; Chang, Jenny C; Rodriguez, Angel A

2016-01-01

Due to the spatial and temporal genomic heterogeneity of breast cancer, genomic sequencing obtained from a single biopsy may not capture the complete genomic profile of tumors. Thus, we propose that cell-free DNA (cfDNA) in plasma may be an alternate source of genomic information to provide comprehensive data throughout a patient's clinical course. We performed a retrospective chart review of 100 patients with stage 4 or high-risk stage 3 breast cancer. The degree of agreement between genomic alterations found in tumor DNA (tDNA) and cfDNA was determined by Cohen's Kappa. Clinical disease progression was compared to mutant allele frequency using a two-sided Fisher's exact test. The presence of mutations and mutant allele frequency was correlated with progression-free survival (PFS) using a Cox proportional hazards model and a log-rank test. The most commonly found genomic alterations were mutations in TP53 and PIK3CA, and amplification of EGFR and ERBB2. PIK3CA mutation and ERBB2 amplification demonstrated robust agreement between tDNA and cfDNA (Cohen's kappa = 0.64 and 0.77, respectively). TP53 mutation and EGFR amplification demonstrated poor agreement between tDNA and cfDNA (Cohen's kappa = 0.18 and 0.33, respectively). The directional changes of TP53 and PIK3CA mutant allele frequency were closely associated with response to therapy (p = 0.002). The presence of TP53 mutation (p = 0.0004) and PIK3CA mutant allele frequency [p = 0.01, HR 1.074 (95 % CI 1.018-1.134)] was excellent predictors of PFS. Identification of selected cancer-specific genomic alterations from cfDNA may be a noninvasive way to monitor disease progression, predict PFS, and offer targeted therapy.

[Analysis on mutation of S gene and P gene of hepatitis B virus in two counties of Sichuan Province].

PubMed

Tong, Wen-Bin; He, Ji-Lan; Sun, Li

2009-02-01

To analyze HBV S gene/P gene mutation in 2 counties (districts) of Sichuan province. HBV DNA were extracted from sera positive both for HBsAg and HBeAg. After PCR and nucleotide sequencing, nucleotide/amino acid mutation in S and P gene were compared and analyzed. Of 47 serum samples from patients with chronic HBV infection, amino acid mutation in 'a' determinant occurred in 12 samples (25.53%,12/47), correlating with T126A, I126T/S, P127T, T131N, M133L, M133T and T140I; high proportion of mutation clustered in first loop of 'a' determinant (92.86%,13/14), rtV207I mutation in C domain of reverse transcription occured in one sample. Naturally occurring mutation in 'a' determinant clustered predominantly in the first loop and usually associated with altered antigenicity, posing a potential threat to successfully vaccinated individuals; Lamivudine-resistant mutant might occur in patient even without nucleotide analogue treatment.

Chronic lymphocytic leukemia with isochromosome 17q: An aggressive subgroup associated with TP53 mutations and complex karyotypes.

PubMed

Collado, Rosa; Puiggros, Anna; López-Guerrero, José Antonio; Calasanz, Ma José; Larráyoz, Ma José; Ivars, David; García-Casado, Zaida; Abella, Eugènia; Orero, Ma Teresa; Talavera, Elisabet; Oliveira, Ana Carla; Hernández-Rivas, Jesús Ma; Hernández-Sánchez, María; Luño, Elisa; Valiente, Alberto; Grau, Javier; Portal, Inmaculada; Gardella, Santiago; Salgado, Anna Camino; Giménez, Ma Teresa; Ardanaz, Ma Teresa; Campeny, Andrea; Hernández, José Julio; Álvarez, Sara; Espinet, Blanca; Carbonell, Félix

2017-11-28

Although i(17q) [i(17q)] is frequently detected in hematological malignancies, few studies have assessed its clinical role in chronic lymphocytic leukemia (CLL). We recruited a cohort of 22 CLL patients with i(17q) and described their biological characteristics, mutational status of the genes TP53 and IGHV and genomic complexity. Furthermore, we analyzed the impact of the type of cytogenetic anomaly bearing the TP53 defect on the outcome of CLL patients and compared the progression-free survival (PFS) and overall survival (OS) of i(17q) cases with those of a group of 38 CLL patients harboring other 17p aberrations. We detected IGHV somatic hypermutation in all assessed patients, and TP53 mutations were observed in 71.4% of the cases. Patients with i(17q) were more commonly associated with complex karyotypes (CK) and tended to have a poorer OS than patients with other anomalies affecting 17p13 (median OS, 44 vs 120 months, P = 0.084). Regarding chromosomal alterations, significant differences in the median OS were found among groups (P = 0.044). In conclusion, our findings provide new insights regarding i(17q) in CLL and show a subgroup with adverse prognostic features. Copyright © 2017 Elsevier B.V. All rights reserved.

Periosteal chondrosarcoma: a histopathological and molecular analysis of a rare chondrosarcoma subtype.

PubMed

Cleven, Arjen H G; Zwartkruis, Evita; Hogendoorn, Pancras C W; Kroon, Herman M; Briaire-de Bruijn, Inge; Bovée, Judith V M G

2015-10-01

Periosteal chondrosarcoma is a rare, malignant cartilage-forming neoplasm originating from the periosteal surface of bone. We collected 38 cases from the archives of the Netherlands Committee on Bone Tumours, with the aim of studying histological features and evaluating the involvement of isocitrate dehydrogenase 1 (IDH1), EXT, Wnt/β-catenin, the pRB pathway (CDK4 and p16), and the TP53 pathway (p53 and MDM2). Histology showed a moderately cellular matrix with mucoid-myxoid changes and, in 42% of cases, formation of a neocortex. Occasional intramedullary extension (26%) and subsequent host bone entrapment (40%) were seen. Histological grading revealed grade 1 (53%) and grade 2 (45%). The EXT1 protein was normally expressed, and mutations in IDH1 were observed in only 15% of cases. pRb signalling was deregulated by loss of p16 expression in 50% of cases, and Wnt signalling was lost in 89%. No alterations were found in CDK4, p53, or MDM2. We report the first large histological and molecular study on periosteal chondrosarcoma showing that histopathological examination and molecular aberrations do not predict prognosis. Although the mutation frequency of IDH1 was low, we confirm the supposed relationship with central chondrosarcoma. Moreover, we identify loss of canonical Wnt signalling and deregulation of pRb signalling as possible events contributing to its histogenesis. © 2015 John Wiley & Sons Ltd.

Genetic and Early Clinical Manifestations of Females Heterozygous for Duchenne/Becker Muscular Dystrophy.

PubMed

Papa, Riccardo; Madia, Francesca; Bartolomeo, Domenico; Trucco, Federica; Pedemonte, Marina; Traverso, Monica; Broda, Paolo; Bruno, Claudio; Zara, Federico; Minetti, Carlo; Fiorillo, Chiara

2016-02-01

Female carriers of Duchenne muscular dystrophy (DMD), although usually asymptomatic, develop muscle weakness up to 17% of the time, and a third present cardiac abnormalities or cognitive impairment. Clinical features of DMD carriers during childhood are poorly known. We describe a cohort of pediatric DMD carriers, providing clinical, genetic, and histopathologic features, with a mean follow-up of 7 years. Fifteen females with a DMD mutation (age range 5 to 18 years) were included. Seven patients (46%) presented with clinically evident symptoms and signs such as limb girdle weakness, abnormal gait, and exercise intolerance. The other eight patients (53%) were evaluated because of an incidental finding of elevated level of creatine kinase. Creatine kinase level was elevated in all, ranging from 392 to 13,000 U/L. Calf hypertrophy was observed in eight patients (53%). No patient developed respiratory or cardiac involvement. The most frequent complication was scoliosis (46%). Four patients (29%) also presented minor learning disabilities or behavioral problems. We performed electromyography in half of patients, showing myopathic pattern in four (53%). Muscle biopsy revealed a mosaic reduction of dystrophin in nine available cases. DMD gene mutations were mostly deletions (71%), resulting in loss of reading frame in five patients (36%). The three patients who experienced the most severe disease course were affected either by a nonsense or frameshift mutation. Our analysis suggests that DMD gene mutations may be suspected in a female child with persistently elevated levels of creatine kinase. Evidence of scoliosis, calf hypertrophy, or myopathic pattern at electromyography may also be helpful, and muscle biopsy is always indicative. DMD carriers should be followed for subtle orthopedic and psychiatric complications during childhood. Copyright © 2016 Elsevier Inc. All rights reserved.

Oncogenic Smad3 signaling induced by chronic inflammation is an early event in ulcerative colitis-associated carcinogenesis.

PubMed

Kawamata, Seiji; Matsuzaki, Koichi; Murata, Miki; Seki, Toshihito; Matsuoka, Katsuyoshi; Iwao, Yasushi; Hibi, Toshifumi; Okazaki, Kazuichi

2011-03-01

Both chronic inflammation and somatic mutations likely contribute to the pathogenesis of ulcerative colitis (UC)-associated dysplasia and cancer. On the other hand, both tumor suppression and oncogenesis can result from transforming growth factor (TGF)-β signaling. TGF-β type I receptor (TβRI) and Ras-associated kinases differentially phosphorylate a mediator, Smad3, to become C-terminally phosphorylated Smad3 (pSmad3C), linker phosphorylated Smad3 (pSmad3L), and both C-terminally and linker phosphorylated Smad3 (pSmad3L/C). The pSmad3C/p21(WAF1) pathway transmits a cytostatic TGF-β signal, while pSmad3L and pSmad3L/C promote cell proliferation by upregulating c-Myc oncoprotein. The purpose of this study was to clarify the alteration of Smad3 signaling during UC-associated carcinogenesis. By immunostaining and immunofluorescence, we compared pSmad3C-, pSmad3L-, and pSmad3L/C-mediated signaling in colorectal specimens representing colitis, dysplasia, or cancer from eight UC patients with signaling in normal colonic crypts. We also investigated p53 expression and mutations of p53 and K-ras genes. We further sought functional meaning of the phosphorylated Smad3-mediated signaling in vitro. As enterocytes in normal crypts migrated upward toward the lumen, cytostatic pSmad3C/p21(WAF1) tended to increase, while pSmad3L/c-Myc shown by progenitor cells gradually decreased. Colitis specimens showed prominence of pSmad3L/C/c-Myc, mediated by TGF-β and tumor necrosis factor (TNF)-α, in all enterocyte nuclei throughout entire crypts. In proportion with increases in frequency of p53 and K-ras mutations during progression from dysplasia to cancer, the oncogenic pSmad3L/c-Myc pathway came to be dominant with suppression of the pSmad3C/p21(WAF1) pathway. Oncogenic Smad3 signaling, altered by chronic inflammation and eventually somatic mutations, promotes UC-associated neoplastic progression by upregulating growth-related protein. Copyright © 2010 Crohn's & Colitis Foundation of America, Inc.

Okadaic acid mediates p53 hyperphosphorylation and growth arrest in cells with wild-type p53 but increases aberrant mitoses in cells with non-functional p53.

PubMed

Milczarek, G J; Chen, W; Gupta, A; Martinez, J D; Bowden, G T

1999-06-01

The protein phosphatase inhibitor and tumor promoting agent okadaic acid (OA), has been shown previously to induce hyperphosphorylation of p53 protein, which in turn correlated with increased transactivation or apoptotic function. However, how the tumor promotion effects of OA relate to p53 tumor supressor function (or dysfunction) remain unclear. Rat embryonic fibroblasts harboring a temperature-sensitive mouse p53 transgene were treated with 50 nM doses of OA. At the wild-type permissive temperature this treatment resulted in: (i) the hyperphosphorylation of sites within tryptic peptides of the transactivation domain of p53; (ii) an increase in p53 affinity for a p21(waf1) promotor oligonucleotide; (iii) an increase in cellular steady state levels of p21(waf1) message; (iv) a G2/M cell cycle blockage in addition to the G1/S arrest previously associated with p53; and (v) no increased incidence of apoptosis. On the other hand, OA treatment at the mutated p53 permissive temperature resulted in a relatively high incidence of aberrant mitosis with no upregulation of p21(waf1) message. These results suggest that while wild-type p53 blocks the proliferative effects of OA through p21(waf1)-mediated growth arrest, cells with non-functional p53 cannot arrest and suffer relatively high levels of OA-mediated aberrant mitoses.

Prognostic impact of KRAS mutation subtypes in 677 patients with metastatic lung adenocarcinomas

PubMed Central

Yu, Helena A.; Sima, Camelia S.; Shen, Ronglai; Kass, Samantha; Gainor, Justin; Shaw, Alice; Hames, Megan; Iams, Wade; Aston, Jonathan; Lovly, Christine M.; Horn, Leora; Lydon, Christine; Oxnard, Geoffrey R.; Kris, Mark G.; Ladanyi, Marc; Riely, Gregory J.

2015-01-01

Background We previously demonstrated that patients with metastatic KRAS mutant lung cancers have a shorter survival compared to patients with KRAS wild type cancers. Recent reports have suggested different clinical outcomes and distinct activated signaling pathways depending on KRAS mutation subtype. To better understand the impact of KRAS mutation subtype, we analyzed data from 677 patients with KRAS mutant metastatic lung cancer. Methods We reviewed all patients with metastatic or recurrent lung cancers found to have KRAS mutations over a 6 year time period. We evaluated the associations between KRAS mutation type, clinical factors, and overall survival in univariate and multivariate analyses. Any significant findings were validated in an external multi-institution patient data set. Results Among 677 patients with KRAS mutant lung cancers (53 at codon 13, 624 at codon 12), there was no difference in overall survival for patients when comparing KRAS transition versus transversion mutations (p=0.99), smoking status (p=0.33) or when comparing specific amino acid substitutions (p=0.20). In our data set, patients with KRAS codon 13 mutant tumors (n=53) had shorter overall survival compared to patients with codon 12 mutant tumors (n=624)( 1.1 vs 1.3 years, respectively, p=0.009), and the findings were confirmed in a multivariate Cox model controlling for age, sex and smoking status (HR 1.52 95% CI 1.11-2.08, p=0.008). In an independent validation set of tumors from 682 patients with stage IV KRAS mutant lung cancers, there was no difference in survival between patients with KRAS codon 13 versus codon 12 mutations (1.0 vs 1.1 years respectively, p=0.41). Conclusions Among individuals with KRAS mutant metastatic lung cancers treated with conventional therapy, there are apparent differences in outcome based on KRAS mutation subtype PMID:25415430

Bcl-2/Bax protein ratio predicts 5-fluorouracil sensitivity independently of p53 status

PubMed Central

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

2000-01-01

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

Using a preclinical mouse model of high-grade astrocytoma to optimize p53 restoration therapy.

PubMed

Shchors, Ksenya; Persson, Anders I; Rostker, Fanya; Tihan, Tarik; Lyubynska, Natalya; Li, Nan; Swigart, Lamorna Brown; Berger, Mitchel S; Hanahan, Douglas; Weiss, William A; Evan, Gerard I

2013-04-16

Based on clinical presentation, glioblastoma (GBM) is stratified into primary and secondary types. The protein 53 (p53) pathway is functionally incapacitated in most GBMs by distinctive type-specific mechanisms. To model human gliomagenesis, we used a GFAP-HRas(V12) mouse model crossed into the p53ER(TAM) background, such that either one or both copies of endogenous p53 is replaced by a conditional p53ER(TAM) allele. The p53ER(TAM) protein can be toggled reversibly in vivo between wild-type and inactive conformations by administration or withdrawal of 4-hydroxytamoxifen (4-OHT), respectively. Surprisingly, gliomas that develop in GFAP-HRas(V12);p53(+/KI) mice abrogate the p53 pathway by mutating p19(ARF)/MDM2 while retaining wild-type p53 allele. Consequently, such tumors are unaffected by restoration of their p53ER(TAM) allele. By contrast, gliomas arising in GFAP-HRas(V12);p53(KI/KI) mice develop in the absence of functional p53. Such tumors retain a functional p19(ARF)/MDM2-signaling pathway, and restoration of p53ER(TAM) allele triggers p53-tumor-suppressor activity. Congruently, growth inhibition upon normalization of mutant p53 by a small molecule, Prima-1, in human GBM cultures also requires p14(ARF)/MDM2 functionality. Notably, the antitumoral efficacy of p53 restoration in tumor-bearing GFAP-HRas(V12);p53(KI/KI) animals depends on the duration and frequency of p53 restoration. Thus, intermittent exposure to p53ER(TAM) activity mitigated the selective pressure to inactivate the p19(ARF)/MDM2/p53 pathway as a means of resistance, extending progression-free survival. Our results suggest that intermittent dosing regimes of drugs that restore wild-type tumor-suppressor function onto mutant, inactive p53 proteins will prove to be more efficacious than traditional chronic dosing by similarly reducing adaptive resistance.

Using a preclinical mouse model of high-grade astrocytoma to optimize p53 restoration therapy

PubMed Central

Shchors, Ksenya; Persson, Anders I.; Rostker, Fanya; Tihan, Tarik; Lyubynska, Natalya; Li, Nan; Swigart, Lamorna Brown; Berger, Mitchel S.; Hanahan, Douglas; Weiss, William A.; Evan, Gerard I.

2013-01-01

Based on clinical presentation, glioblastoma (GBM) is stratified into primary and secondary types. The protein 53 (p53) pathway is functionally incapacitated in most GBMs by distinctive type-specific mechanisms. To model human gliomagenesis, we used a GFAP-HRasV12 mouse model crossed into the p53ERTAM background, such that either one or both copies of endogenous p53 is replaced by a conditional p53ERTAM allele. The p53ERTAM protein can be toggled reversibly in vivo between wild-type and inactive conformations by administration or withdrawal of 4-hydroxytamoxifen (4-OHT), respectively. Surprisingly, gliomas that develop in GFAP-HRasV12;p53+/KI mice abrogate the p53 pathway by mutating p19ARF/MDM2 while retaining wild-type p53 allele. Consequently, such tumors are unaffected by restoration of their p53ERTAM allele. By contrast, gliomas arising in GFAP-HRasV12;p53KI/KI mice develop in the absence of functional p53. Such tumors retain a functional p19ARF/MDM2-signaling pathway, and restoration of p53ERTAM allele triggers p53-tumor–suppressor activity. Congruently, growth inhibition upon normalization of mutant p53 by a small molecule, Prima-1, in human GBM cultures also requires p14ARF/MDM2 functionality. Notably, the antitumoral efficacy of p53 restoration in tumor-bearing GFAP-HRasV12;p53KI/KI animals depends on the duration and frequency of p53 restoration. Thus, intermittent exposure to p53ERTAM activity mitigated the selective pressure to inactivate the p19ARF/MDM2/p53 pathway as a means of resistance, extending progression-free survival. Our results suggest that intermittent dosing regimes of drugs that restore wild-type tumor-suppressor function onto mutant, inactive p53 proteins will prove to be more efficacious than traditional chronic dosing by similarly reducing adaptive resistance. PMID:23542378

Met synergizes with p53 loss to induce mammary tumors that possess features of claudin-low breast cancer

PubMed Central

Knight, Jennifer F.; Lesurf, Robert; Zhao, Hong; Pinnaduwage, Dushanthi; Davis, Ryan R.; Saleh, Sadiq M. I.; Zuo, Dongmei; Naujokas, Monica A.; Chughtai, Naila; Herschkowitz, Jason I.; Prat, Aleix; Mulligan, Anna Marie; Muller, William J.; Cardiff, Robert D.; Gregg, Jeff P.; Andrulis, Irene L.; Hallett, Michael T.; Park, Morag

2013-01-01

Triple-negative breast cancer (TNBC) accounts for ∼20% of cases and contributes to basal and claudin-low molecular subclasses of the disease. TNBCs have poor prognosis, display frequent mutations in tumor suppressor gene p53 (TP53), and lack targeted therapies. The MET receptor tyrosine kinase is elevated in TNBC and transgenic Met models (Metmt) develop basal-like tumors. To investigate collaborating events in the genesis of TNBC, we generated Metmt mice with conditional loss of murine p53 (Trp53) in mammary epithelia. Somatic Trp53 loss, in combination with Metmt, significantly increased tumor penetrance over Metmt or Trp53 loss alone. Unlike Metmt tumors, which are histologically diverse and enriched in a basal-like molecular signature, the majority of Metmt tumors with Trp53 loss displayed a spindloid pathology with a distinct molecular signature that resembles the human claudin-low subtype of TNBC, including diminished claudins, an epithelial-to-mesenchymal transition signature, and decreased expression of the microRNA-200 family. Moreover, although mammary specific loss of Trp53 promotes tumors with diverse pathologies, those with spindloid pathology and claudin-low signature display genomic Met amplification. In both models, MET activity is required for maintenance of the claudin-low morphological phenotype, in which MET inhibitors restore cell-cell junctions, rescue claudin 1 expression, and abrogate growth and dissemination of cells in vivo. Among human breast cancers, elevated levels of MET and stabilized TP53, indicative of mutation, correlate with highly proliferative TNBCs of poor outcome. This work shows synergy between MET and TP53 loss for claudin-low breast cancer, identifies a restricted claudin-low gene signature, and provides a rationale for anti-MET therapies in TNBC. PMID:23509284

Ovarian carcinomas with genetic and epigenetic BRCA1 loss have distinct molecular abnormalities

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

Gilks, C. Blake; Press, Joshua Z.; De Luca, Alessandro

2008-05-02

Subclassification of ovarian carcinomas can be used to guide treatment and determine prognosis. Germline and somatic mutations, loss of heterozygosity (LOH), and epigenetic events such as promoter hypermethylation can lead to decreased expression of BRCA1/2 in ovarian cancers. The mechanism of BRCA1/2 loss is a potential method of subclassifying high grade serous carcinomas. A consecutive series of 49 ovarian cancers was assessed for mutations status of BRCA1 and BRCA2, LOH at the BRCA1 and BRCA2 loci, methylation of the BRCA1 promoter, BRCA1, BRCA2, PTEN, and PIK3CA transcript levels, PIK3CA gene copy number, and BRCA1, p21, p53, and WT-1 immunohistochemistry. Eighteenmore » (37%) of the ovarian carcinomas had germline or somatic BRCA1 mutations, or epigenetic loss of BRCA1. All of these tumors were high-grade serous or undifferentiated type. None of the endometrioid (n=5), clear cell (n=4), or low grade serous (n=2) carcinomas showed loss of BRCA1, whereas 47% of the 38 high-grade serous or undifferentiated carcinomas had loss of BRCA1. It was possible to distinguish high grade serous carcinomas with BRCA1 mutations from those with epigenetic BRCA1 loss: tumors with BRCA1 mutations typically had decreased PTEN mRNA levels while those with epigenetic loss of BRCA1 had copy number gain of PIK3CA. Overexpression of p53 with loss of p21 expression occurred significantly more frequently in high grade serous carcinomas with epigenetic loss of BRCA1, compared to high grade serous tumors without loss of BRCA1. High grade serous carcinomas can be subclassified into three groups: BRCA1 loss (genetic), BRCA1 loss (epigenetic), and no BRCA1 loss. Tumors in these groups show distinct molecular alterations involving the PI3K/AKT and p53 pathways.« less

Ovarian carcinomas with genetic and epigenetic BRCA1 loss havedistinct molecular abnormalities

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

Press, Joshua Z.; De Luca, Alessandro; Boyd, Niki

2007-07-23

Subclassification of ovarian carcinomas can be used to guide treatment and determine prognosis. Germline and somatic mutations, loss of heterozygosity (LOH), and epigenetic events such as promoter hypermethylation can lead to decreased expression of BRCA1/2 in ovarian cancers. The mechanism of BRCA1/2 loss is a potential method of subclassifying high grade serous carcinomas. A consecutive series of 49 ovarian cancers was assessed for mutations status of BRCA1 and BRCA2, LOH at the BRCA1 and BRCA2 loci, methylation of the BRCA1 promoter, BRCA1, BRCA2, PTEN, and PIK3CA transcript levels, PIK3CA gene copy number, and BRCA1, p21, p53, and WT-1 immunohistochemistry. Eighteenmore » (37%) of the ovarian carcinomas had germline or somatic BRCA1 mutations, or epigenetic loss of BRCA1. All of these tumors were high-grade serous or undifferentiated type. None of the endometrioid (n = 5), clear cell (n = 4), or low grade serous (n = 2) carcinomas showed loss of BRCA1, whereas 47% of the 38 high-grade serous or undifferentiated carcinomas had loss of BRCA1. It was possible to distinguish high grade serous carcinomas with BRCA1 mutations from those with epigenetic BRCA1 loss: tumors with BRCA1 mutations typically had decreased PTEN mRNA levels while those with epigenetic loss of BRCA1 had copy number gain of PIK3CA. Overexpression of p53 with loss of p21 expression occurred significantly more frequently in high grade serous carcinomas with epigenetic loss of BRCA1, compared to high grade serous tumors without loss of BRCA1. High grade serous carcinomas can be subclassified into three groups: BRCA1 loss (genetic), BRCA1 loss (epigenetic), and no BRCA1 loss. Tumors in these groups show distinct molecular alterations involving the PI3K/AKT and p53 pathways.« less

TP53-based interaction analysis identifies cis-eQTL variants for TP53BP2, FBXO28, and FAM53A that associate with survival and treatment outcome in breast cancer

PubMed Central

Fagerholm, Rainer; Khan, Sofia; Schmidt, Marjanka K.; GarcClosas, Montserrat; Heikkilä, Päivi; Saarela, Jani; Beesley, Jonathan; Jamshidi, Maral; Aittomäki, Kristiina; Liu, Jianjun; Raza Ali, H.; Andrulis, Irene L.; Beckmann, Matthias W.; Behrens, Sabine; Blows, Fiona M.; Brenner, Hermann; Chang-Claude, Jenny; Couch, Fergus J.; Czene, Kamila; Fasching, Peter A.; Figueroa, Jonine; Floris, Giuseppe; Glendon, Gord; Guo, Qi; Hall, Per; Hallberg, Emily; Hamann, Ute; Holleczek, Bernd; Hooning, Maartje J.; Hopper, John L.; Jager, Agnes; Kabisch, Maria; Investigators, kConFab/AOCS; Keeman, Renske; Kosma, Veli-Matti; Lambrechts, Diether; Lindblom, Annika; Mannermaa, Arto; Margolin, Sara; Provenzano, Elena; Shah, Mitul; Southey, Melissa C.; Dennis, Joe; Lush, Michael; Michailidou, Kyriaki; Wang, Qin; Bolla, Manjeet K.; Dunning, Alison M.; Easton, Douglas F.; Pharoah, Paul D.P .; Chenevix-Trench, Georgia; Blomqvist, Carl; Nevanlinna, Heli

2017-01-01

TP53 overexpression is indicative of somatic TP53 mutations and associates with aggressive tumors and poor prognosis in breast cancer. We utilized a two-stage SNP association study to detect variants associated with breast cancer survival in a TP53-dependent manner. Initially, a genome-wide study (n = 575 cases) was conducted to discover candidate SNPs for genotyping and validation in the Breast Cancer Association Consortium (BCAC). The SNPs were then tested for interaction with tumor TP53 status (n = 4,610) and anthracycline treatment (n = 17,828). For SNPs interacting with anthracycline treatment, siRNA knockdown experiments were carried out to validate candidate genes. In the test for interaction between SNP genotype and TP53 status, we identified one locus, represented by rs10916264 (p(interaction) = 3.44 05E010-5; FDR-adjusted p = 0.0011) in estrogen receptor (ER) positive cases. The rs10916264 AA genotype associated with worse survival among cases with ER-positive, TP53-positive tumors (hazard ratio [HR] 2.36, 95% confidence interval [C.I] 1.45 - 3.82). This is a cis-eQTL locus for FBXO28 and TP53BP2; expression levels of these genes were associated with patient survival specifically in ER-positive, TP53-mutated tumors. Additionally, the SNP rs798755 was associated with survival in interaction with anthracycline treatment (p(interaction) = 9.57 05E010-5, FDR-adjusted p = 0.0130). RNAi-based depletion of a predicted regulatory target gene, FAM53A, indicated that this gene can modulate doxorubicin sensitivity in breast cancer cell lines. If confirmed in independent data sets, these results may be of clinical relevance in the development of prognostic and predictive marker panels for breast cancer. PMID:28179588

Targeting the p53 signaling pathway in cancer therapy - The promises, challenges, and perils

PubMed Central

Stegh, Alexander H.

2012-01-01

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

p53 as a retrovirus-induced oxidative stress modulator.

PubMed

Kim, Soo Jin; Wong, Paul K Y

2015-01-01

Infection of astrocytes by the neuropathogenic mutant of Moloney murine leukemia virus, ts1, exhibits increased levels of reactive oxygen species (ROS) and signs of oxidative stress compared with uninfected astrocytes. Previously, we have demonstrated that ts1 infection caused two separate events of ROS upregulation. The first upregulation occurs during early viral establishment in host cells and the second during the virus-mediated apoptotic process. In this study, we show that virus-mediated ROS upregulation activates the protein kinase, ataxia telangiectasia mutated, which in turn phosphorylates serine 15 on p53. This activation of p53 however, is unlikely associated with ts1-induced cell death. Rather p53 appears to be involved in suppressing intracellular ROS levels in astrocytes under oxidative stress. The activated p53 appears to delay retroviral gene expression by suppressing NADPH oxidase, a superoxide-producing enzyme. These results suggest that p53 plays a role as a retrovirus-mediated oxidative stress modulator. © 2015 The Authors.

P53 nuclear stabilization is associated with FHIT loss and younger age of onset in squamous cell carcinoma of oral tongue

PubMed Central

2014-01-01

Background Squamous cell carcinoma of tongue (SCCT) is expected to harbor unique clinico-pathological and molecular genetic features since a significant proportion of patients are young and exhibit no association with tobacco or alcohol. Methods We determined P53, epidermal growth factor receptor, microsatellite instability, human papilloma virus infection and loss of heterozygosity status at several tumor suppressor loci in one hundred and twenty one oral SCCT (SSCOT) samples and analyzed their association with clinico-pathological features and patient survival. Results Our results revealed a significantly higher incidence of p53 nuclear stabilization in early (as against late) onset SCCOT. FHIT loss was significantly associated with p53 nuclear stabilization and the association was stronger in patients with no history of tobacco use. Samples harboring mutation in p53 DNA binding domain or exhibiting p53 nuclear stabilization, were significantly associated with poor survival. Conclusion Our study has therefore identified distinct features in SCCOT tumorigenesis with respect to age and tobacco exposure and revealed possible prognostic utility of p53. PMID:25152695

Genome-wide CpG island methylation and intergenic demethylation propensities vary among different tumor sites.

PubMed

Lee, Seung-Tae; Wiemels, Joseph L

2016-02-18

The epigenetic landscape of cancer includes both focal hypermethylation and broader hypomethylation in a genome-wide manner. By means of a comprehensive genomic analysis on 6637 tissues of 21 tumor types, we here show that the degrees of overall methylation in CpG island (CGI) and demethylation in intergenic regions, defined as 'backbone', largely vary among different tumors. Depending on tumor type, both CGI methylation and backbone demethylation are often associated with clinical, epidemiological and biological features such as age, sex, smoking history, anatomic location, histological type and grade, stage, molecular subtype and biological pathways. We found connections between CGI methylation and hypermutability, microsatellite instability, IDH1 mutation, 19p gain and polycomb features, and backbone demethylation with chromosomal instability, NSD1 and TP53 mutations, 5q and 19p loss and long repressive domains. These broad epigenetic patterns add a new dimension to our understanding of tumor biology and its clinical implications. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Life science experiments performed in space in the ISS/Kibo facility and future research plans

PubMed Central

Ohnishi, Takeo

2016-01-01

Over the past several years, current techniques in molecular biology have been used to perform experiments in space, focusing on the nature and effects of space radiation. In the Japanese ‘Kibo’ facility in the International Space Station (ISS), the Japan Aerospace Exploration Agency (JAXA) has performed five life science experiments since 2009, and two additional experiments are currently in progress. The first life science experiment in space was the ‘Rad Gene’ project, which utilized two human cultured lymphoblastoid cell lines containing a mutated p53 gene (mp53) and a parental wild-type p53 gene (wtp53) respectively. Four parameters were examined: (i) detecting space radiation–induced DSBs by observing γH2AX foci; (ii) observing p53-dependent gene expression during space flight; (iii) observing p53-dependent gene expression after space flight; and (iv) observing the adaptive response in the two cell lines containing the mutated and wild type p53 genes after exposure to space radiation. These observations were completed and have been reported, and this paper is a review of these experiments. In addition, recent new information from space-based experiments involving radiation biology is presented here. These experiments involve human cultured cells, silkworm eggs, mouse embryonic stem cells and mouse eggs in various experiments designed by other principal investigators in the ISS/Kibo. The progress of Japanese science groups involved in these space experiments together with JAXA are also discussed here. The Japanese Society for Biological Sciences in Space (JSBSS), the Utilization Committee of Space Environment Science (UCSES) and the Science Council of Japan (ACJ) have supported these new projects and new experimental facilities in ISS/Kibo. Currently, these organizations are proposing new experiments for the ISS through 2024. PMID:27130692

Recurrent TP53 missense mutation in cancer patients of Arab descent.

PubMed

Zick, Aviad; Kadouri, Luna; Cohen, Sherri; Frohlinger, Michael; Hamburger, Tamar; Zvi, Naama; Plaser, Morasha; Avital, Eilat; Breuier, Shani; Elian, Firase; Salah, Azzam; Goldberg, Yael; Peretz, Tamar

2017-04-01

Hereditary cancer comprises more than 10% of all breast cancer cases. Identification of germinal mutations enables the initiation of a preventive program that can include early detection or preventive treatment and may also have a major impact on cancer therapy. Several recurrent mutations were identified in the BRCA1/2 genes in Jewish populations however, in other ethnic groups in Israel, no recurrent mutations were identified to date. Our group established panel sequencing in cancer patients to identify recurrent, founder, and new mutations in the heterogeneous and diverse populations in Israel, We evaluated five breast cancer patients of Arab descent diagnosed with cancer before the age of 50 years and identified the previously described TP53 mutation, c.541C>T, R181C (rs587782596), in two women from unrelated Arab families. The two probands were diagnosed with breast cancer at a young age (27 and 34 years) and had significant family history spanning a wide range of tumors (breast cancer (BC), papillary thyroid cancer, glioblastoma multiform (GBM), colon cancer and leukemia). The R181C variant is expected to disrupt p53 at the ASPP2 binding domain but not the DNA binding domain and is defined by Clinvar as likely pathogenic and in HGMD as disease mutation. We further tested 85 unrelated Arab cancer patients and father of a BC carrier patient for TP53 c.541C>T using a real time polymerase chain reaction (RT-PCR) approach and identified four additional carriers, two with BC one with lung cancer, and the father of a BC carrier patient, diagnosed with GBM. Another carrier suffering from BC was identified using a Myriad panel, suggesting a recurrent mutation in this population with a frequency of 5/42 (11.9%) of our selected BC patients. We suggest testing Arab women with a breast cancer at a young age, Arab patients with multiple malignancies, or with suggestive family history for TP53 c.541C>T.

DNA-PK, ATM and ATR collaboratively regulate p53-RPA interaction to facilitate homologous recombination DNA repair

PubMed Central

Serrano, Moises A.; Li, Zhengke; Dangeti, Mohan; Musich, Phillip R.; Patrick, Steve; Roginskaya, Marina; Cartwright, Brian; Zou, Yue

2012-01-01

Homologous recombination (HR) and nonhomologous end-joining (NHEJ) are two distinct DNA double-strand break (DSB) repair pathways. Here we report that DNA-dependent protein kinase (DNA-PK), the core component of NHEJ, partnering with DNA-damage checkpoint kinases ataxia telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR), regulates HR repair of DSBs. The regulation was accomplished through modulation of the p53 and replication protein A (RPA) interaction. We show that upon DNA damage, p53 and RPA were freed from a p53-RPA complex by simultaneous phosphorylations of RPA at the N-terminus of RPA32 subunit by DNA-PK and of p53 at Ser37 and Ser46 in a Chk1/Chk2-independent manner by ATR and ATM, respectively. Neither the phosphorylation of RPA nor of p53 alone could dissociate p53 and RPA. Furthermore, disruption of the release significantly compromised HR repair of DSBs. Our results reveal a mechanism for the crosstalk between HR repair and NHEJ through the co-regulation of p53-RPA interaction by DNA-PK, ATM and ATR. PMID:22797063

DNA-PK, ATM and ATR collaboratively regulate p53-RPA interaction to facilitate homologous recombination DNA repair.

PubMed

Serrano, M A; Li, Z; Dangeti, M; Musich, P R; Patrick, S; Roginskaya, M; Cartwright, B; Zou, Y

2013-05-09

Homologous recombination (HR) and nonhomologous end joining (NHEJ) are two distinct DNA double-stranded break (DSB) repair pathways. Here, we report that DNA-dependent protein kinase (DNA-PK), the core component of NHEJ, partnering with DNA-damage checkpoint kinases ataxia telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR), regulates HR repair of DSBs. The regulation was accomplished through modulation of the p53 and replication protein A (RPA) interaction. We show that upon DNA damage, p53 and RPA were freed from a p53-RPA complex by simultaneous phosphorylations of RPA at the N-terminus of RPA32 subunit by DNA-PK and of p53 at Ser37 and Ser46 in a Chk1/Chk2-independent manner by ATR and ATM, respectively. Neither the phosphorylation of RPA nor of p53 alone could dissociate p53 and RPA. Furthermore, disruption of the release significantly compromised HR repair of DSBs. Our results reveal a mechanism for the crosstalk between HR repair and NHEJ through the co-regulation of p53-RPA interaction by DNA-PK, ATM and ATR.

Full-length mutation search of the TP53 gene in acute myeloid leukemia has increased significance as a prognostic factor.

PubMed

Terada, Kazuki; Yamaguchi, Hiroki; Ueki, Toshimitsu; Usuki, Kensuke; Kobayashi, Yutaka; Tajika, Kenji; Gomi, Seiji; Kurosawa, Saiko; Miyadera, Keiki; Tokura, Taichiro; Omori, Ikuko; Marumo, Atushi; Fujiwara, Yusuke; Yui, Shunsuke; Ryotokuji, Takeshi; Osaki, Yoshiki; Arai, Kunihito; Kitano, Tomoaki; Kosaka, Fumiko; Wakita, Satoshi; Tamai, Hayato; Fukuda, Takahiro; Inokuchi, Koiti

2018-01-01

TP53 gene abnormality has been reported to be an unfavorable prognostic factor in acute myeloid leukemia (AML). However, almost all studies of TP53 gene abnormality so far have been limited to mutation searches in the DNA binding domain. As there have been few reports examining both mutation and deletion over the full-length of the TP53 gene, the clinical characteristics of TP53 gene abnormality have not yet been clearly established. In this study, TP53 gene mutation was observed in 7.3% of the total 412 de novo AML cases (33 mutations in 30 cases), with mutation outside the DNA binding domain in eight cases (27%). TP53 gene deletion was observed in 3.1% of 358 cases. All cases had monoallelic deletion with TP53 gene mutation on the opposite allele. Multivariate analysis demonstrated that TP53 gene mutation in the DNA binding domain and outside the DNA binding domain was an independent poor prognostic factor for overall survival and relapse-free survival among the total cohort and it is also an unfavorable prognostic factor in FLT3-ITD-negative AML cases aged 70 years or below with intermediate cytogenetic prognosis. In stratified treatment, full-length search for TP53 gene mutation is therefore very important.

Ovarian transitional cell carcinoma represents a poorly differentiated form of high-grade serous or endometrioid adenocarcinoma.

PubMed

Takeuchi, Tadahisa; Ohishi, Yoshihiro; Imamura, Hiroko; Aman, Murasaki; Shida, Kaai; Kobayashi, Hiroaki; Kato, Kiyoko; Oda, Yoshinao

2013-07-01

Ovarian transitional cell tumors include Brenner tumors (BTs) and transitional cell carcinoma (TCC; non-BTs) according to the most recent World Health Organization classification. However, it remains a matter of debate whether TCC represents a distinct entity or a morphologic variant of high-grade serous adenocarcinoma (HG-SC). The purpose of this study was to resolve the above question by clarifying the morphologic, immunohistochemical, and molecular features of TCC. We reviewed 488 cases of epithelial ovarian carcinomas and reclassified them on the basis of the most recent World Health Organization classification with the modifications proposed by Köbel and colleagues, and 35 cases of TCC were identified; 25 and 6 TCCs were admixed with HG-SC and endometrioid adenocarcinoma (EC), respectively, and the remaining 4 cases were pure TCC. TCC components were not observed in any clear cell carcinomas or mucinous adenocarcinomas. Only 2 cases of malignant BT were identified. In addition to TCCs, malignant BTs, and related adenocarcinomas, benign and borderline BTs were included in the following immunohistochemical and molecular analyses. Immunohistochemically, pure TCCs, TCCs admixed with HG-SC, and pure HG-SCs were characterized by frequent aberrant p53 expression (diffuse or null pattern) and WT1+/ER+/PR+/IMP2+ immunophenotype, whereas BTs, including benign, borderline, and malignant BTs, were characterized by lack of aberrant p53 expression and WT1-/ER-/PR-/IMP2- immunophenotype. In contrast to the BTs, pure ECs and TCCs admixed with EC showed an ER+/PR+ immunophenotype. Nearly all the tumors with a TP53 gene mutation by molecular analysis showed aberrant p53 staining patterns. In conclusion, TCC is not a distinct entity but a poorly differentiated form of serous or EC, as (1) most TCCs coexist with HG-SC (mostly) or EC (occasionally), and (2) the immunophenotype and molecular features are similar to those of HG-SC or EC but different from those of BTs.

Retroperitoneal dedifferentiated liposarcoma lacking MDM2 amplification in a patient with a germ line CHEK2 mutation.

PubMed

Sadri, Navid; Surrey, Lea F; Fraker, Douglas L; Zhang, Paul J

2014-04-01

Germ line mutations in genes that encode proteins involved in the DNA damage response predispose patients to a variety of tumors. Checkpoint kinase 2, encoded by the CHEK2 gene, is important in transducing the DNA damage response. Germ line CHEK2 mutations are seen in a subset of patients with a familial breast cancer and sarcoma phenotype. We report a case of retroperitoneal dedifferentiated liposarcoma in a 61-year-old female with germ line CHEK2 mutation. MDM2 gene amplification normally present and used to aid in the diagnosis of retroperitoneal dedifferentiated liposarcoma was absent in this case. Lack of MDM2 overexpression has similarly been reported in liposarcomas arising in patients with germ line TP53 mutations. We propose this case may highlight a nonamplified MDM2 phenotype in well- and dedifferentiated liposarcomas arising in patients with germ line mutations of genes involved in p53-associated DNA damage response pathways.

AID protein expression in chronic lymphocytic leukemia/small lymphocytic lymphoma is associated with poor prognosis and complex genetic alterations.

PubMed

Leuenberger, Mona; Frigerio, Simona; Wild, Peter J; Noetzli, Franziska; Korol, Dimitri; Zimmermann, Dieter R; Gengler, Carole; Probst-Hensch, Nicole M; Moch, Holger; Tinguely, Marianne

2010-02-01

The biological behavior of chronic lymphocytic leukemia and small lymphocytic lymphoma is unpredictable. Nonetheless, non-mutated IgV(H) gene rearrangement, ATM (11q22-23) and p53 (17p13) deletion are recognized as unfavorable prognosticators in chronic lymphocytic leukemia. The mRNA expression of activation-induced cytidine deaminase (AID), an enzyme indispensable for somatic hypermutation processes, was claimed to be predictive of non-mutated chronic lymphocytic leukemia cells in blood. Here, we evaluated AID protein expression compared with known molecular and immunohistochemical prognostic indicators in 71 chronic lymphocytic leukemia/small lymphocytic lymphoma patients using a tissue microarray approach. We found AID heterogeneously expressed in tumor cells as shown by colocalization analysis for CD5 and CD23. Ki-67 positive paraimmunoblasts of the proliferation centers displayed the highest expression. This observation is reflected by a significant association of AID positivity with a high proliferation rate (P=0.012). ATM deletion was detected in 10% (6/63) of patients and p53 deletion in 19% (13/67) of patients. Moreover, both ATM (P=0.002) and p53 deletion (P=0.004) were significantly associated with AID. IgV(H) gene mutation was seen in 45% (27/60) of patients. Twenty-five percent (17/69) of patients with AID-positive chronic lymphocytic leukemia/small lymphocytic lymphoma displayed a shorter survival than AID-negative chronic lymphocytic leukemia/small lymphocytic lymphoma patients (61 vs 130 months, P=0.001). Although there was a trend, we could not show an association with the IgV(H) gene mutation status. Taken together, our study shows that AID expression is an indicator of an unfavorable prognosis in chronic lymphocytic leukemia/small lymphocytic lymphoma patients, although it is not a surrogate marker for the IgV(H) status. Furthermore, the microenvironment of proliferation centers seems to influence AID regulation and might be an initiating factor in its transformation.

Cross-species comparison of aCGH data from mouse and human BRCA1- and BRCA2-mutated breast cancers

PubMed Central

2010-01-01

Background Genomic gains and losses are a result of genomic instability in many types of cancers. BRCA1- and BRCA2-mutated breast cancers are associated with increased amounts of chromosomal aberrations, presumably due their functions in genome repair. Some of these genomic aberrations may harbor genes whose absence or overexpression may give rise to cellular growth advantage. So far, it has not been easy to identify the driver genes underlying gains and losses. A powerful approach to identify these driver genes could be a cross-species comparison of array comparative genomic hybridization (aCGH) data from cognate mouse and human tumors. Orthologous regions of mouse and human tumors that are commonly gained or lost might represent essential genomic regions selected for gain or loss during tumor development. Methods To identify genomic regions that are associated with BRCA1- and BRCA2-mutated breast cancers we compared aCGH data from 130 mouse Brca1Δ/Δ;p53Δ/Δ, Brca2Δ/Δ;p53Δ/Δ and p53Δ/Δ mammary tumor groups with 103 human BRCA1-mutated, BRCA2-mutated and non-hereditary breast cancers. Results Our genome-wide cross-species analysis yielded a complete collection of loci and genes that are commonly gained or lost in mouse and human breast cancer. Principal common CNAs were the well known MYC-associated gain and RB1/INTS6-associated loss that occurred in all mouse and human tumor groups, and the AURKA-associated gain occurred in BRCA2-related tumors from both species. However, there were also important differences between tumor profiles of both species, such as the prominent gain on chromosome 10 in mouse Brca2Δ/Δ;p53Δ/Δ tumors and the PIK3CA associated 3q gain in human BRCA1-mutated tumors, which occurred in tumors from one species but not in tumors from the other species. This disparity in recurrent aberrations in mouse and human tumors might be due to differences in tumor cell type or genomic organization between both species. Conclusions The selection of the oncogenome during mouse and human breast tumor development is markedly different, apart from the MYC gain and RB1-associated loss. These differences should be kept in mind when using mouse models for preclinical studies. PMID:20735817