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Sample records for p53 mutation analysis

  1. Dipeptide analysis of p53 mutations and evolution of p53 family proteins.

    PubMed

    Huang, Qiang; Yu, Long; Levine, Arnold J; Nussinov, Ruth; Ma, Buyong

    2014-01-01

    p53 gain-of-function mutations are similar to driver mutations in cancer genes, with both promoting tumorigenesis. Most previous studies focused on residues lost by mutations, providing information related to a dominantly-negative effect. However, to understand gain-of-function mutations, it is also important to investigate what are the distributions of residues gained by mutations. We compile available p53/p63/p73 protein sequences and construct a non-redundant dataset. We analyze the amino acid and dipeptide composition of p53/p63/p73 proteins across evolution and compare them with the gain/loss of amino acids and dipeptides in human p53 following cancer-related somatic mutations. We find that the ratios of amino acids gained via somatic mutations during evolution to those lost through p53 cancer mutations correlate with the ratios found in single nucleotide polymorphisms in the human proteome. The dipeptide mutational gain/loss ratios are inversely correlated with those observed over p53 evolution but tend to follow the increasing p63/p73-like dipeptide propensities. We successfully simulated the p53 cancer mutation spectrum using the dipeptide composition across the p53 family accounting for the likelihood of mutations in p53 codons. The results revealed that the p53 mutation spectrum is dominated not only by p53 evolution but also by reversal of evolution to a certain degree. This article is part of a Special Issue entitled: Computational Proteomics, Systems Biology & Clinical Implications. Guest Editor: Yudong Cai.

  2. Systematic Mutational Analysis of Peptide Inhibition of the p53-MDM2/MDMX Interactions

    PubMed Central

    Li, Chong; Pazgier, Marzena; Li, Changqing; Yuan, Weirong; Liu, Min; Wei, Gang; Lu, Wei-Yue; Lu, Wuyuan

    2010-01-01

    Inhibition of the interaction between the tumor suppressor protein p53 and its negative regulators MDM2 and MDMX is of great interest in cancer biology and drug design. We previously reported a potent duodecimal peptide inhibitor, termed PMI (TSFAEYWNLLSP), of the p53-MDM2 and -MDMX interactions. PMI competes with p53 for MDM2 and MDMX binding at an affinity roughly two orders of magnitude higher than that of 17–28p53 (ETFSDLWKLLPE) of the same length; both peptides adopt nearly identical α-helical conformations in the complexes, where the three highlighted hydrophobic residues Phe, Trp and Leu dominate PMI or 17–28p53 binding to MDM2 and MDMX. To elucidate the molecular determinants for PMI activity and specificity, we performed a systematic Ala scanning mutational analysis of PMI and 17–28p53. The binding affinities for MDM2 and MDMX of a total of 35 peptides including 10 truncation analogs were quantified, affording a complete dissection of energetic contributions of individual residues of PMI and 17–28p53 to MDM2 and MDMX association. Importantly, the N8A mutation turned PMI into the most potent dual specific antagonist of MDM2 and MDMX reported to date, registering respective Kd values of 490 pM and 2.4 nM. The co-crystal structure of N8A-PMI-25–109MDM2 was determined at 1.95 Å, affirming that high-affinity peptide binding to MDM2/MDMX necessitates, in addition to optimized inter-molecular interactions, enhanced helix stability or propensity contributed by non-contact residues. The powerful empirical binding data and crystal structures present a unique opportunity for computational studies of peptide inhibition of the p53-MDM2/MDMX interactions. PMID:20226197

  3. Molecular Genetic Analysis of a Suprasellar Immature Teratoma : Mutation of Exon 4 P53 Gene

    PubMed Central

    Udin, Nujaimin; Ahmad, Ku Asmarina Ku; Ahmad, Farizan; Omar, Effat; Aziz, Mohd Ezanee; Kumar, Raj; Abdullah, Jafri Malin

    2008-01-01

    We described an intracranial immature teratoma in a 13 year old Malay boy who presented with history of chronic headache and blurring of vision. Physical findings revealed bilateral papilloedema but no other localizing sign. A Magnetic Resonance Imaging of the brain revealed a suprasellar well defined lobulated midline heterogenous mass which was intraoperatively described as mainly solid tumour with multiple small cystic component filled with yellowish jelly like material. Histopathological finding confirmed the case as immature teratoma. Molecular genetic analysis of p53 and p27 genes revealed substitution of nucleotide G to C at location nucleotide 12139, exon 4 of gene p53. No alteration was detected at exon 5–6 and 8 of p53 gene and exon 1 and 2 of p27 gene. This is the first case report of an intracranial immature teratoma with genetic mutation occuring in a Malay boy. PMID:22589625

  4. Analysis of p53 mutations and the expression of p53 and p21WAF1/CIP1 protein in 15 cases of sebaceous carcinoma of the eyelid.

    PubMed

    Kiyosaki, Kunihiro; Nakada, Chisato; Hijiya, Naoki; Tsukamoto, Yoshiyuki; Matsuura, Keiko; Nakatsuka, Kazuo; Daa, Tsutomu; Yokoyama, Shigeo; Imaizumi, Masamoto; Moriyama, Masatsugu

    2010-01-01

    The purpose of this study was to detect mutation of the p53 gene, to assess its relationship with p53 or p21(WAF1/CIP1) expression, and to evaluate the correlation between p53 mutation or p21(WAF1/CIP1) expression and clinicopathologic findings in sebaceous carcinoma of the eyelid. Fifteen conventional paraffin-embedded samples of sebaceous carcinoma of the eyelid were analyzed. Using the single-strand conformation polymorphism technique, the authors sequenced coding exons 5-8 of the p53 gene. The expression of p53 and p21(WAF1/CIP1) protein was analyzed by immunohistochemistry. In 10 of the 15 cases (66.7%), point mutations were detected in the p53 gene. CC to TT double-base changes (tandem mutations), which are known to be induced only by UV, were not detected in any of the mutations. Correlations between p53 mutation and expression were found to be statistically significant (P = 0.007). There was no significant correlation between p53 mutation and clinicopathologic findings or p21(WAF1/CIP1) expression. However, there was a significant inverse correlation between p21(WAF1/CIP1) expression and presence of lymph node metastasis (P = 0.007). Among human cancers, sebaceous carcinoma of the eyelid may be one of those showing most frequent mutation of the p53 gene, which may not be caused by exposure to UV. p21(WAF1/CIP1) downregulation may be associated with lymph node metastasis.

  5. 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.

  6. 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…

  7. 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…

  8. Somatic mutation analysis of p53 and ST7 tumor suppressor genes in gastric carcinoma by DHPLC.

    PubMed

    Lu, Chong; Xu, Hui-Mian; Ren, Qun; Ao, Yang; Wang, Zhen-Ning; Ao, Xue; Jiang, Li; Luo, Yang; Zhang, Xue

    2003-12-01

    To verify the effectiveness of denaturing high-performance liquid chromatography (DHPLC) in detecting somatic mutation of p53 gene in gastric carcinoma tissues. The superiority of this method has been proved in the detection of germline mutations, but it was not very affirmative with respect to somatic mutations in tumor specimens. ST7 gene, a candidate tumor suppressor gene identified recently at human chromosome 7q31.1, was also detected because LOH at this site has also been widely reported in stomach cancer. DNA was extracted from 39 cases of surgical gastric carcinoma specimen and their correspondent normal mucosa. Seven fragments spanning the 11 exons were used to detect the mutation of p53 gene and the four exons reported to have mutations in ST7 gene were amplified by PCR and directly analyzed by DHPLC without mixing with wild-type allele. In the analysis of p53 gene mutation, 9 aberrant DHPLC chromatographies were found in tumor tissues, while their normal-adjacent counterparts running in parallel showed a normal shape. Subsequent sequencing revealed nine sequence variations, 1 polymorphism and 8 mutations including 3 mutations not reported before. The mutation rate of p53 gene (21%) was consistent with that previously reported. Furthermore, no additional aberrant chromatography was found when wild-type DNA was added into the DNA of other 30 tumor samples that showed normal shapes previously. The positivity of p53 mutations was significantly higher in intestinal-type carcinomas (40%) than that in diffuse-type (8.33%) carcinomas of the stomach. No mutation of ST7 gene was found. DHPLC is a very convenient method for the detection of somatic mutations in gastric carcinoma. The amount of wild type alleles supplied by the non-tumorous cells in gastric tumor specimens is enough to form heteroduplex with mutant alleles for DHPLC detection. ST7 gene may not be the target gene of inactivation at 7q31 site in gastric carcinoma.

  9. p53 mutation heterogeneity in cancer

    SciTech Connect

    Soussi, T. . E-mail: thierry.soussi@free.fr; Lozano, G.

    2005-06-10

    The p53 gene is inactivated in about 50% of human cancers and the p53 protein is an essential component of the cell response induced by genotoxic stresses such as those generated by radiotherapy or chemotherapy. It is therefore highly likely that these alterations are an important component in tumor resistance to therapy. The particular characteristics of these alterations, 80% of which are missense mutations leading to functionally heterogeneous proteins, make p53 a unique gene in the class of tumor suppressor genes. A considerable number of mutant p53 proteins probably have an oncogenic activity per se and therefore actively participate in cell transformation. The fact that the apoptotic and antiproliferative functions of p53 can be dissociated in certain mutants also suggests another level of complexity in the relationships between p53 inactivation and neoplasia.

  10. Smoking, p53 mutation, and lung cancer.

    PubMed

    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.

  11. Somatic mutation analysis of p53 and ST7 tumor suppressor genes in gastric carcinoma by DHPLC

    PubMed Central

    Lu, Chong; Xu, Hui-Mian; Ren, Qun; Ao, Yang; Wang, Zhen-Ning; Ao, Xue; Jiang, Li; Luo, Yang; Zhang, Xue

    2003-01-01

    AIM: To verify the effectiveness of denaturing high-performance liquid chromatography (DHPLC) in detecting somatic mutation of p53 gene in gastric carcinoma tissues. The superiority of this method has been proved in the detection of germline mutations, but it was not very affirmative with respect to somatic mutations in tumor specimens. ST7 gene, a candidate tumor suppressor gene identified recently at human chromosome 7q31.1, was also detected because LOH at this site has also been widely reported in stomach cancer. METHODS: DNA was extracted from 39 cases of surgical gastric carcinoma specimen and their correspondent normal mucosa. Seven fragments spanning the 11 exons were used to detect the mutation of p53 gene and the four exons reported to have mutations in ST7 gene were amplified by PCR and directly analyzed by DHPLC without mixing with wild-type allele. RESULTS: In the analysis of p53 gene mutation, 9 aberrant DHPLC chromatographies were found in tumor tissues, while their normal-adjacent counterparts running in parallel showed a normal shape. Subsequent sequencing revealed nine sequence variations, 1 polymorphism and 8 mutations including 3 mutations not reported before. The mutation rate of p53 gene (21%) was consistent with that previously reported. Furthermore, no additional aberrant chromatography was found when wild-type DNA was added into the DNA of other 30 tumor samples that showed normal shapes previously. The positivity of p53 mutations was significantly higher in intestinal-type carcinomas (40%) than that in diffuse-type (8.33%) carcinomas of the stomach. No mutation of ST7 gene was found. CONCLUSION: DHPLC is a very convenient method for the detection of somatic mutations in gastric carcinoma. The amount of wild type alleles supplied by the non-tumorous cells in gastric tumor specimens is enough to form heteroduplex with mutant alleles for DHPLC detection. ST7 gene may not be the target gene of inactivation at 7q31 site in gastric carcinoma

  12. 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.
    <...

  13. 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.
    <...

  14. Prognostic value of p53 mutation for poor outcome of Asian primary liver cancer patients: evidence from a cohort study and meta-analysis of 988 patients

    PubMed Central

    Wen, Xiajie; Lu, Fengmin; Liu, Shuang

    2016-01-01

    Several previous studies have investigated the association between gene p53 (p53) mutation and the poor outcome of primary liver cancer (PLC) patients; however, the results remain inconsistent. In the present study, p53 mutation in 60 paired tumor and corresponding nontumor tissues derived from a cohort of 60 PLC patients was systematically analyzed. The results showed that p53 mutation was only an independent risk factor for overall survival (OS), not for recurrence-free survival (RFS), and a meta-analysis was performed to verify this. Online databases were searched up to July 1, 2016. Studies about the association between p53 mutation and the postsurgery survival of PLC patients were collected. A total of 988 patients from eight studies were analyzed; among them, 341 (34.51%) patients had p53 mutation. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were 2.03 (1.64, 2.41) and 2.36 (1.31, 3.42) for OS and RFS, respectively. In conclusion, both the cohort study and meta-analysis suggested that the p53 mutation was associated with postsurgery OS in Asian PLC patients. However, the relationship between p53 mutation and recurrence should be confirmed by further studies. PMID:27994473

  15. P53 Mutation Analysis to Predict Tumor Response in Patients Undergoing Neoadjuvant Treatment for Locally Advanced Breast Cancer

    DTIC Science & Technology

    2006-10-01

    examined have an impact on func However, for some mutations the impact on the transcriptional network or biological response may occur only at low...yeast that enable the assessment of the transactivation potential for wt or mutant p53 proteins towards individual REs in the p53 transcriptional ... network . Each strain differs only by the mutation of interest and the 4-5 a particular RE varies from the consensus. Approach

  16. Analysis of p53 mutation and epidermal growth factor receptor amplification in recurrent gliomas with malignant progression

    SciTech Connect

    Reifenberger, J.; Ring, G.U.; Gies, U.

    1996-07-01

    Genomic alterations and expression of the p53 tumor suppressor gene and the epidermal growth factor receptor gene (EGFR) were investigated in 22 patients with primary World Health Organization (WHO) grade II gliomas that on recurrence had progressed to malignant gliomas of WHO grades III or IV. Mutations of the p53 gene (exons 5 to 8) were found in 12 of 22 primary tumors (10 of 13 astrocytomas, 1 of 7 oligodendrogliomas, 1 of 2 oligoastrocytomas). In each of these cases identical p53 mutations were present in the respective malignant recurrences. In all instances in which the p53 mutation was associated with p53 protein accumulation (10 of 12 cases), the percentage of p53 immunopositive tumor cells had increased from the primary to the recurrent tumor. None of the primary low-grade and none of the recurrent high-grade tumors (7 anaplastic astrocytomas, 10 anaplastic oligodendrogliomas, 4 anaplastic oligoastrocytomas, and 5 glioblastomas) showed evidence of EGFR gene amplification. Our results thus demonstrate that p53 is mutated in a high fraction of low-grade astrocytomas with progression to anaplastic astrocytomas and glioblastomas and that progression in such cases is frequently associated with an increase in the fraction of p53 immunopositive tumor cells. The general absence of EGFR amplification in our tumor series supports the hypothesis that the significance of p53 mutation and EGFR amplification may be different in glioblastomas that developed by progression from low-grade astrocytomas (secondary glioblastomas) compared to glioblastomas that developed rapidly in a de novo manner without a history of previous low-grade tumor (primary glioblastomas). 54 refs., 3 figs., 1 tab.

  17. Mutation analysis of the p53, APC, and p16 genes in the Barrett's oesophagus, dysplasia, and adenocarcinoma.

    PubMed Central

    González, M V; Artímez, M L; Rodrigo, L; López-Larrea, C; Menéndez, M J; Alvarez, V; Pérez, R; Fresno, M F; Pérez, M J; Sampedro, A; Coto, E

    1997-01-01

    AIMS: To study the loss of heterozygosity and the presence of mutations at the p53, p16/CDKN2, and APC genes in Barrett's oesophagus, low grade dysplastic oesophageal epithelium, and adenocarcinoma of the oesophagus; to relate the presence of alterations at these genes with the progression from Barrett's oesophagus to adenocarcinoma. METHODS: DNA was extracted from paraffin blocks containing tissue from Barrett's oesophagus (12 samples), low grade dysplasia (15 cases), and adenocarcinoma (14 cases). Loss of heterozygosity (LOH) at the p53, p16, and APC genes was determined by comparing the autoradiographic patterns of several microsatellite markers between the normal tissue and the malignant tissue counterpart. SSCP was used to determine the presence of mutations at p53 (exons 5 to 8), p16 (exon 2), and APC. Homozygous deletion of the p16 gene was defined through polymerase chain reaction followed by Southern blot. RESULTS: LOH at the p53, p16, and APC genes was not observed in Barrett's oesophagus without dysplasia, and increased to 90% (p53), 89% (p16), and 60% (APC) in the adenocarcinomas. The p53 gene was mutated in only two adenocarcinomas (codons 175 and 245). In one case a mutation at the APC gene (codon 1297) was found. No patient had mutation at the second exon of p16. However, this gene was homozygously deleted in three of the 12 adenocarcinomas. CONCLUSIONS: The tumour suppressor genes p53, p16, and APC are often deleted in adenocarcinomas derived from Barrett's oesophagus. Mutations at these genes are also found in the adenocarcinomas, including the homozygous deletion of the p16 gene. However, the absence of genetic alterations in the Barrett's oesophagus and the low grade dysplastic epithelia suggest that mutations at these genes develop later in the progression from Barrett's oesophagus to adenocarcinoma. Images PMID:9155671

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

    SciTech Connect

    Okazaki, Ryuji; Ootsuyama, Akira; Kakihara, Hiroyo; Mabuchi, Yo; Matsuzaki, Yumi; Michikawa, Yuichi; Imai, Takashi; Norimura, Toshiyuki

    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 situ 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.

  19. Targeted point mutations of p53 lead to dominant-negative inhibition of wild-type p53 function.

    PubMed

    de Vries, Annemieke; Flores, Elsa R; Miranda, Barbara; Hsieh, Harn-Mei; van Oostrom, Conny Th M; Sage, Julien; Jacks, Tyler

    2002-03-05

    The p53 tumor suppressor gene is the most frequently mutated gene in human cancers, and germ-line p53 mutations cause a familial predisposition for cancer. Germ-line or sporadic p53 mutations are usually missense and typically affect the central DNA-binding domain of the protein. Because p53 functions as a tetrameric transcription factor, mutant p53 is thought to inhibit the function of wild-type p53 protein. Here, we studied the possible dominant-negative inhibition of wild-type p53 protein by two different, frequently occurring point mutations. The R270H and P275S mutations were targeted into the genome of mouse embryonic stem cells to allow the analysis of the effects of the mutant proteins expressed in normal cells at single-copy levels. In embryonic stem cells, the presence of a heterozygous point-mutated allele resulted in delayed transcriptional activation of several p53 downstream target genes on exposure to gamma irradiation. Doxorubicin-induced apoptosis was severely affected in the mutant embryonic stem cells compared with wild-type cells. Heterozygous mutant thymocytes had a severe defect in p53-dependent apoptotic pathways after treatment with gamma irradiation or doxorubicin, whereas p53-independent apoptotic pathways were intact. Together these data demonstrate that physiological expression of point-mutated p53 can strongly limit overall cellular p53 function, supporting the dominant-negative action of such mutants. Also, cells heterozygous for such mutations may be compromised in terms of tumor suppression and response to chemotherapeutic agents.

  20. P53 Mutation and Epigenetic Imprinted IGF2/H19 Gene Analysis in Mesenchymal Stem Cells Derived from Amniotic Fluid, Amnion, Endometrium, and Wharton's Jelly.

    PubMed

    Phermthai, Tatsanee; Pokathikorn, Puttachart; Wichitwiengrat, Suparat; Thongbopit, Sasiprapa; Tungprasertpol, Kittima; Julavijitphong, Suphakde

    2017-09-15

    Mesenchymal stem cells (MSC) are promising cells for medical therapy. In in vitro expansion, MSC can give rise to progeny with genomic and epigenomic alterations, resulting in senescence, loss of terminal differentiation, and transformation to cancer. However, MSC genome protects its genetic instability by a guardian function of the P53 tumor suppressor gene and epigenetic balance system during MSC culture. Mutations of P53 and epigenetic alterations have been reported to disrupt the quality and quantity of MSC and initiate tumorigenesis. We monitor P53 and epigenetic changes in MSC derived from amniotic fluid (AF-MSC), amnion membrane (AM-MSC), endometrium (EM-MSC), and Wharton's jelly (WJ-MSC) by the missense mutation analysis of the P53 gene and the expression levels of P53, and epigenetic insulin-like growth factor 2 (IGF2) and H19-imprinted genes. Our work demonstrates a variation of P53 expression among different MSC types. AF-MSC has a high P53 expression level with retaining a stability of P53 expression throughout a long culture period, whereas EM-MSC and WJ-MSC showed variation of P53 gene expression during culture. Epigenetic analysis showed a stable H19 expression pattern in AF-MSC, AM-MSC, and EM-MSC culture, whereas H19 expression fluctuated in WJ-MSC culture. We conclude that gene instability can be found during in vitro MSC expansion. With awareness to MSC quality and safety in MSC transformation risk, P53 mutation and IGF2 and H19-imprinted gene analysis should be applied to monitor in therapeutic-grade MSC. We also demonstrated that AF-MSC is one of the most interesting MSC for medical therapy because of its high genomic stability and epigenetic fidelity.

  1. p53 gene mutations in asbestos associated cancers.

    PubMed

    Liu, B C; Fu, D C; Miao, Q; Wang, H H; You, B R

    1998-09-01

    The accumulation of mutant p53 protein in cancer cells was observed by immunohistochemistry analysis. DNA was extracted from paraffin-embedded tissue. Exons 5, 7 and 8 were amplified and studied by PCR-SSCP and sequencing analysis. Ten cases of asbestos associated cancer tissue were studied, of which five cases had adenocarcinoma, and the other five had mesothelioma, squamous carcinoma, small cell lung cancer, adenosquamous carcinoma and malignant lymphoma respectively. Employing monoclonal antibody PAb1801, five cases were found to be mutant p53 protein positive. Seven cases were found to have mutations by PCR-SSCP. A total of 7 cases (8 mutations) were found to be positive and 4 cases were found to be positive by both of these analyses. Of the 8 mutations found by SSCP analysis, 4(50%, 4/8) were clustered in exon 8. A high mutation frequency was noticed in adenocarcinoma (80%, 4/5). Sequencing analysis on two specimens revealed two hotspot mutations. In codon 234, TAC for tyrosin was mutated to AAC for asparagine by a T to A transversion of the first letter. In codon 273, CGT for arginine was mutated to AGT for serine by a C to A transversion of the first letter. In conclusion, the mutation of p53 gene is common in asbestos associated cancers. However, the mutational spectrum of asbestos associated cancers might be different from that of non-asbestos associated cancers.

  2. Analysis of EGFR, KRAS and P53 mutations in lung cancer using cells in the curette lavage fluid obtained by bronchoscopy.

    PubMed

    Yamaguchi, Fumihiro; Kugawa, Satoshi; Tateno, Hidetsugu; Kokubu, Fumio; Fukuchi, Kunihiko

    2012-12-01

    Histopathological samples are commonly used for molecular testing to detect both oncogenes and tumor-suppressor genes in lung cancer. The purpose of this study was to determine the efficacy of using curette lavage fluid for molecular testing to detect EGFR, KRAS and P53 mutations in lung cancer patients. Samples were obtained from 77 lung cancer patients by bronchoscopy at the time of diagnosis, collected by scraping the site of the primary tumor lesion with a curette. DNA was extracted from cells in the curette lavage fluid, and PCRs were performed to amplify mutation hot spot regions in the EGFR, KRAS and P53 genes. The PCR products were direct-sequenced to detect mutations of each gene. The reference sequence of each gene was obtained from GenBank. Overall, 27% (21 of 77) were found with EGFR mutations, 1% (1 of 77) with KRAS mutations, and 36% (28 of 77) with P53 mutations. KRAS mutations were not detected in patients harboring mutations in either EGFR or P53. P53 mutations were identified in 38% (8 of 21) of the patients with EGFR mutations, all of who had advanced lung cancer. Of these patients, a 62-year-old female current smoker was given EGFR-TKI as third-line therapy, with no improvement in clinical symptoms or results of radiographic examination. Multivariate analysis indicated that P53 mutation rates in advanced-stage lung cancer were significantly higher than those in early-stage lung cancer (P=.017). In contrast, EGFR mutation rates were not significantly associated with staging. L747S in EGFR, described as a mutation associated with secondary resistance to EGFR-TKI, was detected in three patients who had never received EGFR-TKI, including one SCLC patient. It is possible to analyze EGFR, KRAS and P53 mutations using curette lavage fluid collected from lung cancer patients. This is useful when sufficient amounts of tumor samples cannot be obtained. Data from the current study suggest that EGFR mutations in concert with P53 mutations accelerate cancer

  3. Hitting cancers' weak spots: vulnerabilities imposed by p53 mutation.

    PubMed

    Gurpinar, Evrim; Vousden, Karen H

    2015-08-01

    The tumor suppressor protein p53 plays a critical role in limiting malignant development and progression. Almost all cancers show loss of p53 function, through either mutation in the p53 gene itself or defects in the mechanisms that activate p53. While reactivation of p53 can effectively limit tumor growth, this is a difficult therapeutic goal to achieve in the many cancers that do not retain wild type p53. An alternative approach focuses on identifying vulnerabilities imposed on cancers by virtue of the loss of or alterations in p53, to identify additional pathways that can be targeted to specifically kill or inhibit the growth of p53 mutated cells. These indirect ways of exploiting mutations in p53 - which occur in more than half of all human cancers - provide numerous exciting therapeutic possibilities.

  4. Analysis of p53, K-ras gene mutation & Helicobacter pylori infection in patients with gastric cancer & peptic ulcer disease at a tertiary care hospital in north India.

    PubMed

    Saxena, Ashish; Shukla, Sanket Kumar; Prasad, Kashi Nath; Ghoshal, Uday Chand

    2012-10-01

    Mutations in the oncogene and tumour suppressor genes play an important role in carcinogenesis. We investigated the association of p53 and K-ras gene mutation and Helicobacter pylori infection in patients with gastric cancer (GC) and peptic ulcer disease (PUD) attending a tertiary care hospital in north India. In total, 348 adult patients [62 GC, 45 PUD and 241 non-ulcer dyspepsia (NUD)] who underwent an upper gastrointestinal endoscopy were enrolled. H. pylori infection was diagnosed by rapid urease test, culture, histopathology and PCR. Mutation in the exon 5-8 of p53 gene was analyzed by PCR-single stranded conformational polymorphism (SSCP) and confirmed by sequence analysis. K-ras gene codon 12 mutation was analyzed by PCR-based restriction fragment length polymorphism. Overall p53 gene mutation was found in 4.6 per cent of the study population, and its distribution in GC, PUD and NUD was 21, 4.4 and 0.4 per cent, respectively. p53 gene mutation was significantly higher in patients with GC than PUD (P<0.05) and NUD (P<0.001). No difference in p53 gene mutation was observed between H. pylori infected and non-infected individuals. K-ras gene mutation was absent in all the patients. Our results show that p53 gene mutation may be associated with gastric carcinogenesis independent to H. pylori infection and absence of K-ras gene mutation questions its role in the pathogenesis of GC and PUD in Indian patients.

  5. Analysis of p53, K-ras gene mutation & Helicobacter pylori infection in patients with gastric cancer & peptic ulcer disease at a tertiary care hospital in north India

    PubMed Central

    Saxena, Ashish; Shukla, Sanket Kumar; Prasad, Kashi Nath; Ghoshal, Uday Chand

    2012-01-01

    Background & objectives: Mutations in the oncogene and tumour suppressor genes play an important role in carcinogenesis. We investigated the association of p53 and K-ras gene mutation and Helicobacter pylori infection in patients with gastric cancer (GC) and peptic ulcer disease (PUD) attending a tertiary care hospital in north India. Methods: In total, 348 adult patients [62 GC, 45 PUD and 241 non-ulcer dyspepsia (NUD)] who underwent an upper gastrointestinal endoscopy were enrolled. H. pylori infection was diagnosed by rapid urease test, culture, histopathology and PCR. Mutation in the exon 5-8 of p53 gene was analyzed by PCR-single stranded conformational polymorphism (SSCP) and confirmed by sequence analysis. K-ras gene codon 12 mutation was analyzed by PCR-based restriction fragment length polymorphism. Results: Overall p53 gene mutation was found in 4.6 per cent of the study population, and its distribution in GC, PUD and NUD was 21, 4.4 and 0.4 per cent, respectively. p53 gene mutation was significantly higher in patients with GC than PUD (P<0.05) and NUD (P<0.001). No difference in p53 gene mutation was observed between H. pylori infected and non-infected individuals. K-ras gene mutation was absent in all the patients. Interpretation & conclusions: Our results show that p53 gene mutation may be associated with gastric carcinogenesis independent to H. pylori infection and absence of K-ras gene mutation questions its role in the pathogenesis of GC and PUD in Indian patients. PMID:23168708

  6. Microvessel density and p53 mutations in advanced-stage epithelial ovarian cancer.

    PubMed

    Nadkarni, Niyati J; Geest, Koen De; Neff, Traci; Young, Barry De; Bender, David P; Ahmed, Amina; Smith, Brian J; Button, Anna; Goodheart, Michael J

    2013-04-30

    We planned to determine the relationship between angiogenesis and p53 mutational status in advanced-stage epithelial ovarian cancer. Using 190 tumor samples from patients with stage III and IV ovarian cancer we performed p53 sequencing, immunohistochemistry, and CD31 microvessel density (MVD) determination. MVD was elevated in tumors with p53 null mutations compared to p53 missense mutation or no mutation. Disease recurrence was increased with higher MVD in both unadjusted and adjusted analyses. In adjusted analysis, p53 null mutation was associated with increased recurrence and worse overall survival. Worse overall survival and increased recurrence risk were also associated with the combination of CD31 MVD values >25 vessels/HPF and any p53 mutation. P53 mutation status and MVD may have prognostic significance in patients with advanced-stage ovarian cancer. Tumors with p53 null mutations are likely to be more vascular, contributing to decreased survival and increased recurrence probability.

  7. P53 mutations and cancer: a tight linkage

    PubMed Central

    Pisconti, Salvatore; Della Vittoria Scarpati, Giuseppina

    2016-01-01

    P53 is often mutated in solid tumors, in fact, somatic changes involving the gene encoding for p53 (TP53) have been discovered in more than 50% of human malignancies and several data confirmed that p53 mutations represent an early event in cancerogenesis. Main p53 functions consist in cell cycle arrest, DNA repair, senescence and apoptosis induction in response to mutagenic stimuli, and, to exert those functions, p53 acts as transcriptional factor. Recent data have highlighted another very important role of p53, consisting in regulate cell metabolism and cell response to oxidative stress. Majority of tumor suppressor genes, such as adenomatous polyposis coli (APC), retinoblastoma-associated protein (RB) and Von-Hippel-Lindau (VHL) are inactivated by deletion or early truncation mutations in tumors, resulting in the decreased or loss of expression of their proteins. Differently, most p53 mutations in human cancer are missense mutations, which result in the production of full-length mutant p53 proteins. It has been reported that mutant p53 proteins and wild type p53 proteins often regulate same cellular biological processes with opposite effects. So, mutant p53 has been reported to supply the cancer cells of glucose and nutrients, and, to avoid reactive oxygen species (ROS) mediated damage during oxidative stress. These last features are able to render tumor cells resistant to ionizing radiations and chemotherapy. A future therapeutic approach in tumors bearing p53 mutations may be to deplete cancer cells of their energy reserves and antioxidants. PMID:28149884

  8. A multiple primary carcinoma consisting of leukoplakia and SCC: a case report with p53 mutation analysis.

    PubMed

    Hassan, Nur Mohammad Monsur; Tada, Mitsuhiro; Shindoh, Masanobu; Hamada, Jun-Ichi; Kashiwazaki, Haruhiko; Shimo, Tsuyoshi; Ashikaga, Yuichi; Yamazaki, Yutaka; Sasaki, Akira; Moriuchi, Tetsuya; Inoue, Nobuo

    2010-11-01

    Patients with an oral squamous cell carcinoma (OSCC) often develop multiple malignant lesions. This report examined whether individual tumours developed in a patient show the same genetic alteration, such as p53 mutations. This case study describes three SCCs and three leukoplakias which developed simultaneously in a single 67-year-old Japanese man. A p53 mutation was detected in two of the three SCCs and one of the three leukoplakias. One SCC had a missense mutation at codon 285 (GAG>AAG, Glu>Lys) and the other a nonsense mutation at codon 336, and the leukoplakia had a missense mutation at codon 273 (CGT>CAT, Arg>His). This case showed that individual oral tumours may have different genetic changes even when they develop in a single patient. Therefore, this report provided strong evidence that in cases of multiple tumours it is necessary to design tailor-made therapies for each individual tumour rather than a single standardised therapy for all multiple tumours.

  9. Thyroid adenomatous nodule with bizarre nuclei: a case report and mutation analysis of the p53 gene.

    PubMed

    Sato, Katsuaki; Shimode, Yuzo; Hirokawa, Mitsuyoshi; Ueda, Yoshimichi; Katsuda, Shogo

    2008-01-01

    We present a rare case of adenomatous nodule with bizarre nuclei. The patient was incidentally found to have a nodule in the left lobe of the thyroid gland by ultrasonographic examination. Papillary thyroid carcinoma was suspected by fine needle aspiration cytology, and hemithyroidectomy was performed. The demarcated 1.5-cm nodule had a multinodular appearance with various features, including micro- and macrofollicular components, cystic degeneration, a hyalinized area, and a papillary structure. Hyperchromatic bizarre nuclei with cytoplasmic inclusions were restrictively observed in the microfollicular area. The bizarre nuclei demonstrated diffuse p53 protein immmunoreactivity, but no mutation in exons 5-9 of the p53 gene was detected. The bizarre nuclei were reactive for anti-5-methyl-2'-deoxycytidine antibody, indicating the enclosure of presumably inactive methylated DNA. The intranuclear cytoplasmic inclusions (ICIs) were proven to contain vimentin and beta-catenin by immunohistochemistry. In this case, a degenerative process is involved in the formation of bizarre nuclei because of the compression by surrounding micronodules, unidentifiable mitotic figures, and a quite low proliferative activity. This case suggests that bizarre nuclei and ICIs, which might be identical to those of papillary carcinomas, can be seen in benign thyroid lesions, and overdiagnosis should be avoided regardless of immunohistochemical overexpression of p53.

  10. p53: its mutations and their impact on transcription.

    PubMed

    Vaughan, Catherine; Pearsall, Isabella; Yeudall, Andrew; Deb, Swati Palit; Deb, Sumitra

    2014-01-01

    p53 is a tumor suppressor protein whose key function is to maintain the integrity of the cell. Mutations in p53 have been found in up to 50 % of all human cancers and cause an increase in oncogenic phenotypes such as proliferation and tumorigenicity. Both wild-type and mutant p53 have been shown to transactivate their target genes, either through directly binding to DNA, or indirectly through protein-protein interactions. This review discusses possible mechanisms behind both wild-type and mutant p53-mediated transactivation and touches on the concept of addiction to mutant p53 of cancer cells and how that may be used for future therapies.

  11. Immunohistochemical staining patterns of p53 can serve as a surrogate marker for TP53 mutations in ovarian carcinoma: an immunohistochemical and nucleotide sequencing analysis.

    PubMed

    Yemelyanova, Anna; Vang, Russell; Kshirsagar, Malti; Lu, Dan; Marks, Morgan A; Shih, Ie Ming; Kurman, Robert J

    2011-09-01

    Immunohistochemical staining for p53 is used as a surrogate for mutational analysis in the diagnostic workup of carcinomas of multiple sites including ovarian cancers. Strong and diffuse immunoexpression of p53 is generally interpreted as likely indicating a TP53 gene mutation. The immunoprofile that correlates with wild-type TP53, however, is not as clear. In particular, the significance of completely negative immunostaining is controversial. The aim of this study was to clarify the relationship of the immunohistochemical expression of p53 with the mutational status of the TP53 gene in ovarian cancer. A total of 57 ovarian carcinomas (43 high-grade serous ovarian/peritoneal carcinomas, 2 malignant mesodermal mixed tumors (carcinosarcomas), 2 low-grade serous carcinomas, 4 clear cell carcinomas, 1 well-differentiated endometrioid carcinoma, and 5 carcinomas with mixed epithelial differentiation) were analyzed for TP53 mutations by nucleotide sequencing (exons 4-9), and subjected to immunohistochemical analysis of p53 expression. Thirty six tumors contained functional mutations and 13 had wild type TP53. Five tumors were found to harbor known TP53 polymorphism and changes in the intron region were detected in three. Tumors with wild-type TP53 displayed a wide range of immunolabeling patterns, with the most common pattern showing ≤10% of positive cells in 6 cases (46%). Mutant TP53 was associated with 60-100% positive cells in 23 cases (64% of cases). This pattern of staining was also seen in three cases with wild-type TP53. Tumors that were completely negative (0% cells staining) had a mutation of TP53 in 65% of cases and wild-type TP53 in 11%. Combining two immunohistochemical labeling patterns associated with TP53 mutations (0% and 60-100% positive cells), correctly identified a mutation in 94% of cases (P<0.001). Immunohistochemical analysis can be used as a robust method for inferring the presence of a TP53 mutation in ovarian carcinomas. In addition to a

  12. Analysis of different versions of the IARC p53 database with respect to G-->T transversion mutation frequencies and mutation hotspots in lung cancer of smokers and non-smokers.

    PubMed

    Paschke, T

    2000-11-01

    Analysis of the IARC p53 database revealed a large number of discrepancies in the classification of smoking status for identical lung cancer entries in different versions of the database. In addition, no statistically significant differences in G-->T transversion mutation frequencies or in mutational hotspots at codons 157, 248 and 273 were found in the R3 version of the database between p53 sequences from smoking and non-smoking lung cancer patients. The possible influence of confounding factors on p53 mutation spectra was demonstrated as illustrated by the impact of ethnicity on G-->T transversion mutation frequencies.

  13. Quantifying levels of p53 mutation in mouse skin tumors.

    PubMed

    Verkler, Tracie L; Couch, Letha H; Howard, Paul C; Parsons, Barbara L

    2005-06-01

    Allele-specific competitive blocker PCR (ACB-PCR) amplification and quantification was developed for mouse p53 codon 270 CGT-->TGT base substitution and codon 244/245 AAC/CGC-->AAT/TGC tandem mutation. PCR products corresponding to p53 mutant and wild-type DNA sequences were generated. These DNAs were mixed in known proportions to construct samples with defined mutant fractions and the allele-specific detection of each mutation was systematically optimized. Each assay was used to analyze eight simulated solar light (SSL)-induced tumors. By analyzing mutant fraction (MF) standards in parallel with PCR products generated from tumor samples, p53 mutants could be quantified as subpopulations within the tumors. All eight tumors contained detectable levels of p53 codon 270 CGT-->TGT mutation. Three tumors had p53 MFs between 10(-4) and 10(-3). Five tumors had p53 MFs between 10(-3) and 10(-2). None of the eight mouse skin tumors had measurable levels of p53 codon 244/245 tandem mutation. Frequent detection of p53 codon 270 CGT-->TGT mutation provides additional evidence that a pyrimidine dinucleotide overlapping a methylated CpG site (Pyr(me)CG) is a susceptible target for SSL-induced mutagenesis. The absence of p53 codon 244/245 mutation in tumors may be explained by its mutant p53 phenotype and/or indicate that this site is not methylated. These initial results indicate that p53 codon 270 CGT-->TGT mutation may be a sensitive biomarker for SSL- or UV-induced mutagenesis. This mutational endpoint may be useful for evaluating the co-carcinogenicity of compounds administered in combination with UV or SSL.

  14. The isolation of an RNA aptamer targeting to p53 protein with single amino acid mutation

    PubMed Central

    Chen, Liang; Rashid, Farooq; Shah, Abdullah; Awan, Hassaan M.; Wu, Mingming; Liu, An; Wang, Jun; Zhu, Tao; Luo, Zhaofeng; Shan, Ge

    2015-01-01

    p53, known as a tumor suppressor, is a DNA binding protein that regulates cell cycle, activates DNA repair proteins, and triggers apoptosis in multicellular animals. More than 50% of human cancers contain a mutation or deletion of the p53 gene, and p53R175 is one of the hot spots of p53 mutation. Nucleic acid aptamers are short single-stranded oligonucleotides that are able to bind various targets, and they are typically isolated from an experimental procedure called systematic evolution of ligand exponential enrichment (SELEX). Using a previously unidentified strategy of contrast screening with SELEX, we have isolated an RNA aptamer targeting p53R175H. This RNA aptamer (p53R175H-APT) has a significantly stronger affinity to p53R175H than to the wild-type p53 in both in vitro and in vivo assays. p53R175H-APT decreased the growth rate, weakened the migration capability, and triggered apoptosis in human lung cancer cells harboring p53R175H. Further analysis actually indicated that p53R175H-APT might partially rescue or correct the p53R175H to function more like the wild-type p53. In situ injections of p53R175H-APT to the tumor xenografts confirmed the effects of this RNA aptamer on p53R175H mutation in mice. PMID:26216949

  15. The isolation of an RNA aptamer targeting to p53 protein with single amino acid mutation.

    PubMed

    Chen, Liang; Rashid, Farooq; Shah, Abdullah; Awan, Hassaan M; Wu, Mingming; Liu, An; Wang, Jun; Zhu, Tao; Luo, Zhaofeng; Shan, Ge

    2015-08-11

    p53, known as a tumor suppressor, is a DNA binding protein that regulates cell cycle, activates DNA repair proteins, and triggers apoptosis in multicellular animals. More than 50% of human cancers contain a mutation or deletion of the p53 gene, and p53R175 is one of the hot spots of p53 mutation. Nucleic acid aptamers are short single-stranded oligonucleotides that are able to bind various targets, and they are typically isolated from an experimental procedure called systematic evolution of ligand exponential enrichment (SELEX). Using a previously unidentified strategy of contrast screening with SELEX, we have isolated an RNA aptamer targeting p53R175H. This RNA aptamer (p53R175H-APT) has a significantly stronger affinity to p53R175H than to the wild-type p53 in both in vitro and in vivo assays. p53R175H-APT decreased the growth rate, weakened the migration capability, and triggered apoptosis in human lung cancer cells harboring p53R175H. Further analysis actually indicated that p53R175H-APT might partially rescue or correct the p53R175H to function more like the wild-type p53. In situ injections of p53R175H-APT to the tumor xenografts confirmed the effects of this RNA aptamer on p53R175H mutation in mice.

  16. p53 mutation, but not p53 overexpression, correlates with survival in head and neck squamous cell carcinoma.

    PubMed Central

    Mineta, H.; Borg, A.; Dictor, M.; Wahlberg, P.; Akervall, J.; Wennerberg, J.

    1998-01-01

    Survival in squamous cell carcinoma of the head and neck (HNSCC) was compared with overexpression and mutation of the p53 gene. Archival tissue from 77 tumours was analysed for protein expression using immunohistochemistry (IHC) with the monoclonal antibody Do-7, and for the presence of mutation in exons 5-8 using single-stranded conformation polymorphism (SSCP), followed by DNA sequencing in SSCP-positive cases. p53 expression was scored as high (>70% nuclei stained) in 25 (32%) tumours, as intermediate (10-70% nuclei stained) in 19 (25%) tumours and as low (<10% nuclei stained) in 33 (43%) tumours. Twelve (18%) tumours exhibited gene mutation (ten missense and two nonsense mutations) and an additional five tumours contained changes that could not result in amino acid substitution or protein truncation. There was no correlation between gene expression and mutation, mutations being equally frequent in tumours with either high (4/25), intermediate (4/19) or low protein expression (4/33). Fifty-eight patients were eligible for survival analysis. There was a strong correlation between p53 mutation and cause-specific survival; median survival among mutated cases was 12.5 months compared with >160 months among non-mutated patients (P < 0.005). There was no correlation between p53 overexpression and survival. The results suggest that p53 mutation status is an important prognostic factor in HNSCC, and that IHC analysis of protein overexpression is an inadequate measure of gene mutation in these tumours. Images Figure 1 PMID:9792155

  17. Pancreatic adenocarcinomas frequently show p53 gene mutations.

    PubMed Central

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

    1993-01-01

    Thirty-four pancreatic adenocarcinomas were studied for the presence of p53 gene mutations by the single-strand conformation polymorphism method and by direct sequencing of PCR-amplified fragments. p53 protein expression was immunohistochemically evaluated using monoclonal PAb1801 and polyclonal CM1 antibodies. Mutations were detected in 14 cases. The transitions were six G to A and two A to G; the transversions were one C to G and two A to C; the remaining three were frameshift mutations. Immunostaining results were identical with both antibodies. Nuclear immunohistochemical p53-positive cells were found in nine p53 mutated cases and in 12 cases in which no mutation was detected. In most of these latter cases only a minority of cancer cells showed immunohistochemical positivity. Twenty-nine cases, including all p53 mutated cancers, were known to contain codon 12 Ki-ras gene mutations. Also in the light of the demonstrated cooperation of ras and p53 gene alterations in the transformation of cultured cells, our data suggest that p53 mutation is one of the genetic defects that may have a role in the pathogenesis of a proportion of pancreatic cancers. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:8494051

  18. Characteristics and survival of patients with advanced cancer and p53 mutations.

    PubMed

    Said, Rabih; Ye, Yang; Hong, David S; Janku, Filip; Fu, Siqing; Naing, Aung; Wheler, Jennifer J; Kurzrock, Razelle; Thomas, Christoforos; Palmer, Gary A; Hess, Kenneth R; Aldape, Kenneth; Tsimberidou, Apostolia M

    2014-06-15

    P53 mutations are associated with invasive tumors in mouse models. We assessed the p53mutations and survival in patients with advanced cancer treated in the Phase I Program. Of 691 tested patients, 273 (39.5%) had p53 mutations. Patients with p53 mutations were older (p<.0001) and had higher numbers of liver metastases (p=.005). P53 mutations were associated with higher numbers of other aberrations; PTEN (p=.0005) and HER2 (p=.003)aberrations were more common in the p53 mutation group. No survival difference was observed between patients with p53 mutations and those with wild-type p53. In patients with wild-type p53 and other aberrations, patients treated with matched-therapy against the additional aberrations had longer survival compared to those treated with non-matched-therapy or those who received no therapy (median survival, 26.0 vs. 11.8 vs. 9.8 months, respectively; p= .0007). Results were confirmed in a multivariate analysis (p= .0002). In the p53 mutation group with additional aberrations, those who received matched-therapy against the additional aberrations had survival similar to those treated with non-matched-therapy or those who received no therapy (p=.15). In conclusion, our results demonstrated resistance to matched-targeted therapy to the other aberrations in patients with p53 mutations and emphasize the need to overcome this resistance.

  19. Sensitivity of single-strand conformation polymorphism (SSCP) analysis in detecting p53 point mutations in tumors with mixed cell populations

    SciTech Connect

    Wu, J.K.; Zhen Ye; Darras, B.T. Tufts Univ., Boston, MA )

    1993-06-01

    Mutations in the p53 tumor-suppressor gene are commonly found in human cancers of diverse origin. Once of a number of methods developed to analyze large numbers of DNA samples for specific mutations is the single-strand conformation polymorphism (SSCP) analysis. This method is particularly well suited for analysis of tissues, such as brain tumors, with mixed cell populations. It takes advantage of the fact that, in a mixed cell population containing DNA with and without a mutation (e.g., the p53 gene mutation), both molecular species will be amplified by the PCR. A mutation within a PCR-amplified DNA fragment will alter the secondary structure of the amplified fragment and affect its electrophoretic mobility in a nondenaturing gel. The DNA fragments with the mutation are detected as an aberrantly migrating allele that can be seen concurrently with the wild-type allele. Although many studies have used this technique to screen for p53 mutations in tumors, with detection of a number of different mutations the limit of detection of point mutations in a background of wild-type DNA is not known. To test this, mixtures of mutant DNA from tumor D317 with a G-to-A point mutation in codon 272 of the p53 gene; or from tumor D263 (with a G-to-A point mutation in codon 175 of the p53 gene) and wild-type DNA from leukocytes, in ratios of 1:100, 5:95, 10:90, 15:85, 50:50, and 30:70, were prepared. The mixtures containing 100 ng of DNA were amplified using standard PCR technique. After the double-stranded DNAs were denatured, the DNA samples were loaded and electrophoresed on a nondenaturing acrylamide gel. The mutant allele was detectable even when the ratio of mutant to wild-type DNA was 5:95 in tumor D317. For tumor D263, the mutant allele was detectable when the ratio of mutant to wild-type DNA was 15:85, and it was not detectable at 10:90.

  20. Acquisition of p53 mutations in response to the non-genotoxic p53 activator Nutlin-3.

    PubMed

    Aziz, M H; Shen, H; Maki, C G

    2011-11-17

    Wild-type p53 is a stress-responsive tumor suppressor and potent growth inhibitor. Genotoxic stresses (for example, ionizing and ultraviolet radiation or chemotherapeutic drug treatment) can activate p53, but also induce mutations in the P53 gene, and thus select for p53-mutated cells. Nutlin-3a (Nutlin) is pre-clinical drug that activates p53 in a non-genotoxic manner. Nutlin occupies the p53-binding pocket of murine double minute 2 (MDM2), activating p53 by blocking the p53-MDM2 interaction. Because Nutlin neither binds p53 directly nor introduces DNA damage, we hypothesized Nutlin would not induce P53 mutations, and, therefore, not select for p53-mutated cells. To test this, populations of SJSA-1 (p53 wild-type) cancer cells were expanded that survived repeated Nutlin exposures, and individual clones were isolated. Group 1 clones were resistant to Nutlin-induced apoptosis, but still underwent growth arrest. Surprisingly, while some Group 1 clones retained wild-type p53, others acquired a heterozygous p53 mutation. Apoptosis resistance in Group 1 clones was associated with decreased PUMA induction and decreased caspase 3/7 activation. Group 2 clones were resistant to both apoptosis and growth arrest induced by Nutlin. Group 2 clones had acquired mutations in the p53-DNA-binding domain and expressed only mutant p53s that were induced by Nutlin treatment, but were unable to bind the P21 and PUMA gene promoters, and unable to activate transcription. These results demonstrate that non-genotoxic p53 activation (for example, by Nutlin treatment) can lead to the acquisition of somatic mutations in p53 and select for p53-mutated cells. These findings have implications for the potential clinical use of Nutlin and other small molecule MDM2 antagonists.

  1. Mutational analysis of the N-ras, p53, p16INK4a, CDK4, and MC1R genes in human congenital melanocytic naevi.

    PubMed

    Papp, T; Pemsel, H; Zimmermann, R; Bastrop, R; Weiss, D G; Schiffmann, D

    1999-08-01

    Eighteen human congenital melanocytic naevi (CMN) from 17 patients were screened for activating point mutations in the oncogenes N-ras and CDK4 and for sequence variants in the MC1R gene by combined RFLP-PCR/SSCP analysis. In addition, all lesions were screened for deletions and point mutations in the tumour suppressor genes p53 and p16INK4a (CDKN2A) by combined multiplex PCR/SSCP analysis. Positive screening data were specified by sequencing of the corresponding PCR product. Activating point mutations in the N-ras gene (nine CAA (Gln) to AAA (Lys) transversions and one CAA (Gln) to CGA (Arg) transition at codon 61) were detected at high frequency (56%). Furthermore, three missense mutations (V92M) and two silent mutations (CGA (Arg) to CGG (Arg), codon 213, exon 6) were found in the MC1R and p53 genes, respectively. No mutations were found in p16 or CDK4. The activated N-ras oncogene, which is also found in human cutaneous melanomas, may constitute a potential risk factor for melanoma formation within CMN.

  2. Patterns and Biologic Features of p53 Mutation Types in Korean Breast Cancer Patients

    PubMed Central

    Kim, Hyung Won; Lee, Hak Min; Hwang, Seung Hyun; Ahn, Sung Gwe; Lee, Kyung-A

    2014-01-01

    Purpose The p53 gene is one of the most frequently mutated genes in breast cancer. We investigated the patterns and biologic features of p53 gene mutation and evaluated their clinical significance in Korean breast cancer patients. Methods Patients who underwent p53 gene sequencing were included. Mutational analysis of exon 5 to exon 9 of the p53 gene was carried out using polymerase chain reaction-denaturing high performance liquid chromatography and direct sequencing. Results A total of 497 patients were eligible for the present study and p53 gene mutations were detected in 71 cases (14.3%). Mutation of p53 was significantly associated with histologic grading (p<0.001), estrogen receptor and progesterone receptor status (p<0.001), HER2 status (p<0.001), Ki-67 (p=0.028), and tumor size (p=0.004). The most frequent location of p53 mutations was exon 7 and missense mutation was the most common type of mutation. Compared with patients without mutation, there was a statistically significant difference in relapse-free survival of patients with p53 gene mutation and missense mutation (p=0.020, p=0.006, respectively). Only p53 missense mutation was an independent prognostic factor for relapse-free survival in multivariate analysis, with an adjusted hazard ratio of 2.29 (95% confidence interval, 1.08-4.89, p=0.031). Conclusion Mutation of the p53 gene was associated with more aggressive clinicopathologic characteristics and p53 missense mutation was an independent negative prognostic factor in Korean breast cancer patients. PMID:24744791

  3. 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.

  4. Depression of p53-independent Akt survival signals after high-LET radiation in mutated p53 cells

    NASA Astrophysics Data System (ADS)

    Ohnishi, Takeo; Takahashi, Akihisa; Nakagawa, Yosuke

    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. Recently, it has been suggested 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 the activities of 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 signals were analyzed with Western blotting analysis 1 h, 2 h, 3 h and 6 h after irradiation. Cell cycle distributions after irradiation were assayed with flow cytometric analysis.Akt-related protein levels were decreased when cells were irradiated with high-LET radiation. High-LET radiation increased G _{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 depresses cell growth by suppressing Akt-related signals, even in the mp53 cells.

  5. Mutations in p53 as potential molecular markers for human breast cancer

    SciTech Connect

    Runnebaum, I.B.; Nagarajan, M.; Bowman, M.; Soto, D.; Sukumar, S. )

    1991-12-01

    Based on the high incidence of loss of heterozygosity for loci on chromosome 17p in the vicinity of the p53 locus in human breast tumors. The authors investigated the frequency and effects of mutations in the p53 tumor suppressor gene in mammary neoplasia. They examined the p53 gene in 20 breast cancer cell lines and 59 primary breast tumors. Northern blot analysis, immunoprecipitation, and nucleotide sequencing analysis revealed aberrant mRNA expression, over-expression of protein, and point mutations in the p53 gene in 50% of the cell line tested. A multiplex PCR assay was developed to search for deletions in the p53 genomic locus. Multiplex PCR of genomic DNA showed that up to 36% of primary tumors contained aberrations in the p53 locus. Mutations in exons 5-9 of the p53 gene were found in 10 out of 59 (17%) of the primary tumors studied by single-stranded conformation polymorphism analysis. They conclude that, compared to amplification of HER2/NEU, MYC, or INT2 oncogene loci, p53 gene mutations and deletions are the most frequently observed genetic change in breast cancer related to a single gene. Correlated to disease status, p53 gene mutations could prove to be a valuable marker for diagnosis and/or prognosis of breast neoplasia.

  6. Detection of a novel point mutation in the p53 gene in grade II astrocytomas by PCR-SSCP analysis with additional Klenow treatment.

    PubMed

    Chawengchao, B; Petmitr, S; Ponglikitmongkol, M; Chanyavanich, V; Sangruji, T; Theerapuncharoen, V; Hayashi, K; Thangnipon, W

    2001-01-01

    Using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) with additional Klenow treatment and direct sequencing mutations in the p53 tumor suppressor gene were analyzed from 21 cases of human astrocytomas. Three cases had p53 gene mutations: two of them were glioblastomas showing a point mutation, one in exon 5 and the other in 6. The last one was a gemistocytic astrocytoma showing a point mutation in exon 5. The frequency of p53 gene mutations in the astrocytomas examined was 14.3% (3 out of 21). No SSCP alterations were observed in any of the p53 fragments amplified from WHO grade I pilocytic astrocytomas and WHO grade III anaplastic astrocytomas. Further examination by direct sequencing showed that two mutations of glioblastomas had single-base substitutions resulting in silent and missense mutations, whereas one of the gemistocytic astrocytomas had a double-base substitution resulting in a missense mutation. The present studies revealed that all mutations were located outside the hot spots and, interestingly, one of them disclosed a missense mutation in exon 5 at codon 166, which was first detected in a grade II astrocytoma (gemistocytic type). It is possible that the missense mutation at this codon may be associated with special risk factors for the development of astrocytic tumors in Thai patients.

  7. Lung cancer stem cells, p53 mutations and MDM2.

    PubMed

    Gadepalli, Venkat Sundar; Deb, Swati Palit; Deb, Sumitra; Rao, Raj R

    2014-01-01

    Over the past few decades, advances in cancer research have enabled us to understand the different mechanisms that contribute to the aberrant proliferation of normal cells into abnormal cells that result in tumors. In the pursuit to find cures, researchers have primarily focused on various molecular level changes that are unique to cancerous cells. In humans, about 50 % or more cancers have a mutated tumor suppressor p53 gene thereby resulting in accumulation of p53 protein and losing its function to activate the target genes that regulate cell cycle and apoptosis. Extensive research conducted in murine cancer models with activated p53, loss of p53, or p53 missense mutations have facilitated researchers to understand the role of this key protein. Despite the identification of numerous triggers that causes lung cancer specific cure still remain elusive. One of the primary reasons attributed to this is due to the fact that the tumor tissue is heterogeneous and contains numerous sub-populations of cells. Studies have shown that a specific sub-population of cells termed as cancer stem cells (CSCs) drive the recurrence of cancer in response to standard chemotherapy. These CSCs are mutated cells with core properties similar to those of adult stem cells. They reside in a microenvironment within the tumor tissue that supports their growth and make them less susceptible to drug treatment. These cells possess properties of symmetric self-renewal and migration thus driving tumor formation and metastasis. Therefore, research specifically targeting these cells has gained prominence towards developing new therapeutic agents against cancer. This chapter focuses on lung cancer stem cells, p53 mutations noted in these cells, and importance of MDM2 interactions. Further, research approaches for better understanding of molecular mechanisms that drive CSC function and developing appropriate therapies are discussed.

  8. The carcinogenic role of oncogenic HPV and p53 gene mutation in cervical adenocarcinomas.

    PubMed

    Andersson, S; Hellström, A-C; Ren, Zhi-Ping; Wilander, E

    2006-01-01

    Thirty tumors were collected from our archive of cervical adenocarcinomas. They were examined with respect to the content of oncogenic HPV and presence of mutations in the p53 gene exons 5 through 8. Furthermore, available clinical information on the cases was reviewed. For the detection of p53 gene and presence of oncogenic HPV, PCR followed by direct sequence analysis of the amplified DNA was employed. Seventeen tumors were identified as HPV-positive, comprising both HPV types 18 and 16. Six cases showed a p53 gene mutation, of which five were of the missence and one of the silent type. No statistical correlation between the occurrence of oncogenic HPV and presence of p53 gene mutation (p = 0.67) was recorded. Among the tumors with p53 gene mutation, three were HPV-positive and three were HPV-negative. The determination of p53 gene mutations was not related to clinical findings such as the stage of the tumor or presence of metastases of the lymph nodes. However, p53 gene mutations were somewhat more prevalent in low differentiated tumors (p < 0.02). The results indicate that oncogenic HPV and p53 gene mutations have independent carcinogenic roles in cervical adenocarcinomas.

  9. Persistent p53 Mutations in Single Cells from Normal Human Skin

    PubMed Central

    Ling, Gao; Persson, Åsa; Berne, Berit; Uhlén, Mathias; Lundeberg, Joakim; Ponten, Fredrik

    2001-01-01

    Epidermal clones of p53-mutated keratinocytes are abundant in chronically sun-exposed skin and may play an important role in early development of skin cancer. Advanced laser capture microdissection enables genetic analysis of targeted cells from tissue sections without contamination from neighboring cells. In this study p53 gene mutations were characterized in single cells from normal, chronically sun-exposed skin. Biopsies were obtained from skin subjected to daily summer sun and skin totally protected from the sun by blue denim fabric. Using laser capture microdissection, 172 single-cell samples were retrieved from four biopsies and analyzed using single-cell polymerase chain reaction and direct DNA sequencing. A total of 14 different mutations were identified in 26 of 99 keratinocytes from which the p53 gene could be amplified. Mutations displayed a typical UV signature and were detected in both scattered keratinocytes and in a small cluster of p53-immunoreactive keratinocytes. This minute epidermal p53 clone had a diameter of 10 to 15 basal cells. Two missense mutations were found in all layers of epidermis within the p53 clone. The presented data show that p53 mutations are common in normal skin and that a clone of keratinocytes with a mutated p53 gene prevailed despite 2 months of total protection from ultraviolet light. PMID:11583952

  10. Characterization of p53 gene mutations in a Brazilian population with oral squamous cell carcinomas.

    PubMed

    Chaves, Anna C M; Cherubini, Karen; Herter, Nilton; Furian, Roque; Santos, Diogenes S; Squier, Christopher; Domann, Frederick E

    2004-02-01

    Mutations in the p53 tumor suppressor gene are present in approximately 50% of all human cancers. We sought to determine the frequency and type of p53 mutations in squamous cell carcinomas (SCC) of the oral cavity in a Brazilian population. To identify p53 mutations we used PCR-SSCP in tumor tissue microdissected from paraffin- embedded and from fresh-frozen sections followed by direct sequencing of SSCP bands with altered electrophoretic mobility. We identified p53 mutations in 40% of the human SCC analyzed. The mutations were of a broad spectrum, with a preponderance of G --> A and A --> G transitions with an apparent hotspot at the CpG dinucleotide at codon 290. Patient samples were stratified according to tobacco and alcohol consumption as well as by anatomic location of the tumor, and although trends did emerge, no statistically significant associations were obtained between the occurance of TP53 mutations and these lifestyle habits. We conclude that p53 mutations are common among oral cavity cancers in this population, and stress the significance of this study since it is the first analysis of p53 mutation in oral cancer in a southern Brazilian population.

  11. Diet, Helicobacter pylori, and p53 mutations in gastric cancer: a molecular epidemiology study in Italy.

    PubMed

    Palli, D; Caporaso, N E; Shiao, Y H; Saieva, C; Amorosi, A; Masala, G; Rice, J M; Fraumeni, J F

    1997-12-01

    A series of 105 gastric cancer (GC) cases with paraffin-embedded specimens interviewed in a previous population-based case-control study conducted in a high-risk area around Florence, Italy, was examined for the presence of p53 mutations. Overall, 33 of 105 cases had a mutation (p53+) identified by single-strand conformational polymorphism and confirmed by sequencing (Y-H. Shiao et al., submitted for publication). p53+ cases had a more traditional dietary pattern (i.e., corn meal mush, meat soup, and other homemade dishes) and reported less frequent consumption of raw vegetables (particularly lettuce and raw carrots). A positive association with a high nitrite intake and a negative association with raw vegetables and diffuse type histology persisted in a multivariate analysis. In addition, p53+ cases tended to be located in the upper portion of the stomach and to be associated with advanced age and blood group A. No relation was found between the presence of p53 mutations and histologically defined Helicobacter pylori infection, smoking history, family history of gastric cancer, education, and social class. Of the 33 p53+ cases, 19 had G:C-->A:T transitions at CpG sites. These tumors tended to occur in females and in association with H. pylori infection but not other risk factors. The remaining 14 cases with a p53 mutation had mainly transversions but also two deletions and two transitions at non-CpG sites. These tumors showed a strong positive association with a traditional dietary pattern and with the estimated intake of selected nutrients (nitrite, protein, and fat, particularly from animal sources). The findings of this case-case analysis suggest that p53 mutations at non-CpG sites are related to exposure to alkylating compounds from diet, whereas p53 mutations at CpG sites might be related to H. pylori infection.

  12. Restoring expression of wild-type p53 suppresses tumor growth but does not cause tumor regression in mice with a p53 missense mutation

    PubMed Central

    Wang, Yongxing; Suh, Young-Ah; Fuller, Maren Y.; Jackson, James G.; Xiong, Shunbin; Terzian, Tamara; Quintás-Cardama, Alfonso; Bankson, James A.; El-Naggar, Adel K.; Lozano, Guillermina

    2011-01-01

    The transcription factor p53 is a tumor suppressor. As such, the P53 gene is frequently altered in human cancers. However, over 80% of the P53 mutations found in human cancers are missense mutations that lead to expression of mutant proteins that not only lack p53 transcriptional activity but exhibit new functions as well. Recent studies show that restoration of p53 expression leads to tumor regression in mice carrying p53 deletions. However, the therapeutic efficacy of restoring p53 expression in tumors containing p53 missense mutations has not been evaluated. Here we demonstrate that restoring wild-type p53 expression halted tumor growth in mice inheriting a p53R172H missense mutation that is equivalent to a P53 missense mutation detected in approximately 6% of human cancers. However, it did not lead to tumor regression, as was observed in mice lacking p53. We further showed that the dominant-negative effect of the mutant p53 encoded by p53R172H dampened the activity of the restored wild-type p53. We therefore conclude that in a mutant p53 background, p53 restoration has the therapeutic potential to suppress tumor progression. Our findings support using p53 restoration as a strategy to treat human cancers with P53 missense mutations and provide direction for optimizing p53 restoration in cancer therapy. PMID:21285512

  13. Restoring expression of wild-type p53 suppresses tumor growth but does not cause tumor regression in mice with a p53 missense mutation.

    PubMed

    Wang, Yongxing; Suh, Young-Ah; Fuller, Maren Y; Jackson, James G; Xiong, Shunbin; Terzian, Tamara; Quintás-Cardama, Alfonso; Bankson, James A; El-Naggar, Adel K; Lozano, Guillermina

    2011-03-01

    The transcription factor p53 is a tumor suppressor. As such, the P53 gene is frequently altered in human cancers. However, over 80% of the P53 mutations found in human cancers are missense mutations that lead to expression of mutant proteins that not only lack p53 transcriptional activity but exhibit new functions as well. Recent studies show that restoration of p53 expression leads to tumor regression in mice carrying p53 deletions. However, the therapeutic efficacy of restoring p53 expression in tumors containing p53 missense mutations has not been evaluated. Here we demonstrate that restoring wild-type p53 expression halted tumor growth in mice inheriting a p53(R172H) missense mutation that is equivalent to a P53 missense mutation detected in approximately 6% of human cancers. However, it did not lead to tumor regression, as was observed in mice lacking p53. We further showed that the dominant-negative effect of the mutant p53 encoded by p53(R172H) dampened the activity of the restored wild-type p53. We therefore conclude that in a mutant p53 background, p53 restoration has the therapeutic potential to suppress tumor progression. Our findings support using p53 restoration as a strategy to treat human cancers with P53 missense mutations and provide direction for optimizing p53 restoration in cancer therapy.

  14. Germline p53 mutations are frequently detected in young children with rhabdomyosarcoma.

    PubMed Central

    Diller, L; Sexsmith, E; Gottlieb, A; Li, F P; Malkin, D

    1995-01-01

    We investigated the possibility that a proportion of children with sporadic rhabdomyosarcoma (RMS) carry constitutional mutations of the p53 tumor suppressor gene. 33 patients with sporadic RMS at two large outpatient pediatric oncology clinics submitted blood samples. Genomic DNA was extracted from peripheral blood leukocytes and PCR was used to amplify exons 2-11 of the p53 gene. Amplified genomic DNA was screened for the presence of germline p53 mutations using single-strand conformation polymorphism (SSCP) analysis. The DNA sequence of those samples that showed aberrant migration of bands on SSCP analysis was determined to identify the precise nature of the gene mutations. Patient records were reviewed to assess clinical correlates of the mutant p53 carrier state. Heterozygous constitutional mutations were detected in 3/33 patient samples screened. Two of these missense mutations are located in exon 7 and one in exon 8 of the p53 gene. The presence of mutations was not correlated with tumor histology, stage, or site. However, an association between young age at diagnosis and presence of a constitutional p53 mutation was noted: 3/13 children under the age of 3 yr at diagnosis carried mutations, whereas none of 20 children over 3 yr of age at diagnosis harbored a detectable constitutional mutation. These results in children with RMS corroborates previous findings in other clinical settings suggesting that the mutant p53 carrier state may predispose individuals to malignancy at an early age. Although this study did not assess whether the mutations were preexisting or new germline alterations, assessment of close relatives of RMS patients for cancer risk and predictive genetic testing may be indicated. Images PMID:7706467

  15. Determination of HER2 and p53 Mutations by Sequence Analysis Method and EGFR/Chromosome 7 Gene Status by Fluorescence in Situ Hybridization for the Predilection of Targeted Therapy Modalities in Immunohistochemically Triple Negative Breast Carcinomas in Turkish Population.

    PubMed

    Pala, Emel Ebru; Bayol, Umit; Keskin, Elif Usturali; Ozguzer, Alp; Kucuk, Ulku; Ozer, Ozge; Koc, Altug

    2015-09-01

    Triple negative breast cancer (TNBC), an agressive subtype accounts nearly 15 % of all breast carcinomas. Conventional chemotherapy is the only treatment modality thus new, effective targeted therapy methods have been investigated. Epidermal growth factor receptor (EGFR) inhibitors give hope according to the recent studies results. Also therapeutic agents have been tried against aberrant p53 signal activity as TNBC show high p53 mutation rates. Our aim was to detect the incidence of mutations/amplifications identified in TNBC in our population. Here we used sequence analysis to detect HER2 (exon 18-23), p53 (exon 5-8) mutations; fluorescence in situ hybridization (FISH) method to analyse EGFR/chromosome 7 centromere gene status in 82 immunohistochemically TNBC. Basaloid phenotype was identified in 49 (59.8 %) patients. EGFR amplification was noted in 5 cases (6.1 %). All EGFR amplified cases showed EGFR overexpression by immunohistochemistry (IHC). p53 mutations were identified in 33 (40.2 %) cases. Almost 60 % of the basal like breast cancer cases showed p53 mutation. Only one case showed HER2 mutation (exon 20:g.36830_3). Our results showed that gene amplification is not the unique mechanism in EGFR overexpression. IHC might be used in the decision of anti-EGFR therapy in routine practice. p53 mutation rate was lower than the rates reported in the literature probably due to ethnic differences and low sensitivity of sanger sequences in general mutation screening. We also established the rarity of HER2 mutation in TNBC. In conclusion EGFR and p53 are the major targets in TNBC also for our population.

  16. p53 exon 5 mutations as a prognostic indicator of shortened survival in non-small-cell lung cancer.

    PubMed

    Vega, F J; Iniesta, P; Caldés, T; Sanchez, A; López, J A; de Juan, C; Diaz-Rubio, E; Torres, A; Balibrea, J L; Benito, M

    1997-01-01

    Inactivation of the tumour-suppressor gene p53 has been described as one of the most common molecular changes found in lung tumours. Our purpose was to study the prognostic value of p53 alterations and to determine whether some specific mutation type in the p53 gene could be associated with poor clinical evolution in non-small-cell lung cancer (NSCLC) patients. To this end, we studied 81 resected primary NSCLCs in order to detect p53 alterations. p53 protein accumulation was analysed using immunohistochemistry methods; p53 gene mutations in exons 5-9 were studied using polymerase chain reaction-single-strand conformation polymorphism and sequencing techniques. p53 protein was immunodetected in 46.9% of lung carcinomas and 44.7% of p53-immunopositive tumours showed p53 mutations. Survival analysis was performed on 62 patients. No survival differences were found for patients with or without p53 immunopositivity. A shorter survival was found in patients with underlying p53 gene mutations, mainly in patients with squamous cell lung tumours; the worst prognosis was found when mutations were located in exon 5 (P = 0.007). In conclusion, the location of p53 mutations might be considered as a prognostic indicator for the evaluation of poor clinical evolution in NSCLC patients.

  17. p53 exon 5 mutations as a prognostic indicator of shortened survival in non-small-cell lung cancer.

    PubMed Central

    Vega, F. J.; Iniesta, P.; Caldés, T.; Sanchez, A.; López, J. A.; de Juan, C.; Diaz-Rubio, E.; Torres, A.; Balibrea, J. L.; Benito, M.

    1997-01-01

    Inactivation of the tumour-suppressor gene p53 has been described as one of the most common molecular changes found in lung tumours. Our purpose was to study the prognostic value of p53 alterations and to determine whether some specific mutation type in the p53 gene could be associated with poor clinical evolution in non-small-cell lung cancer (NSCLC) patients. To this end, we studied 81 resected primary NSCLCs in order to detect p53 alterations. p53 protein accumulation was analysed using immunohistochemistry methods; p53 gene mutations in exons 5-9 were studied using polymerase chain reaction-single-strand conformation polymorphism and sequencing techniques. p53 protein was immunodetected in 46.9% of lung carcinomas and 44.7% of p53-immunopositive tumours showed p53 mutations. Survival analysis was performed on 62 patients. No survival differences were found for patients with or without p53 immunopositivity. A shorter survival was found in patients with underlying p53 gene mutations, mainly in patients with squamous cell lung tumours; the worst prognosis was found when mutations were located in exon 5 (P = 0.007). In conclusion, the location of p53 mutations might be considered as a prognostic indicator for the evaluation of poor clinical evolution in NSCLC patients. Images Figure 1 PMID:9218731

  18. Functional repair of p53 mutation in colorectal cancer cells using trans-splicing.

    PubMed

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

    2015-02-10

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

  19. Functional repair of p53 mutation in colorectal cancer cells using trans-splicing

    PubMed Central

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

    2015-01-01

    Mutation in the p53 gene is arguably the most frequent type of gene-specific alterations in human cancers. Current p53-based gene therapy contains the administration of wt-p53 or the suppression of mutant p53 expression in p53-defective cancer cells. We hypothesized that trans-splicing could be exploited as a tool for the correction of mutant p53 transcripts in p53-mutated human colorectal cancer (CRC) cells. In this study, the plasmids encoding p53 pre-trans-splicing molecules (PTM) were transfected into human CRC cells carrying p53 mutation. The plasmids carrying p53-PTM repaired mutant p53 transcripts in p53-mutated CRC cells, which resulted in a reduction in mutant p53 transcripts and an induction of wt-p53 simultaneously. Intratumoral administration of adenovirus vectors carrying p53 trans-splicing cassettes suppressed the growth of tumor xenografts. Repair of mutant p53 transcripts by trans-splicing induced cell-cycle arrest and apoptosis in p53-defective colorectal cancer cells in vitro and in vivo. In conclusion, the present study demonstrated for the first time that trans-splicing was exploited as a strategy for the repair of mutant p53 transcripts, which revealed that trans-splicing would be developed as a new therapeutic approach for human colorectal cancers carrying p53 mutation. PMID:25576916

  20. 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

  1. Bioinformatics study of cancer-related mutations within p53 phosphorylation site motifs.

    PubMed

    Ji, Xiaona; Huang, Qiang; Yu, Long; Nussinov, Ruth; Ma, Buyong

    2014-07-29

    p53 protein has about thirty phosphorylation sites located at the N- and C-termini and in the core domain. The phosphorylation sites are relatively less mutated than other residues in p53. To understand why and how p53 phosphorylation sites are rarely mutated in human cancer, using a bioinformatics approaches, we examined the phosphorylation site and its nearby flanking residues, focusing on the consensus phosphorylation motif pattern, amino-acid correlations within the phosphorylation motifs, the propensity of structural disorder of the phosphorylation motifs, and cancer mutations observed within the phosphorylation motifs. Many p53 phosphorylation sites are targets for several kinases. The phosphorylation sites match 17 consensus sequence motifs out of the 29 classified. In addition to proline, which is common in kinase specificity-determining sites, we found high propensity of acidic residues to be adjacent to phosphorylation sites. Analysis of human cancer mutations in the phosphorylation motifs revealed that motifs with adjacent acidic residues generally have fewer mutations, in contrast to phosphorylation sites near proline residues. p53 phosphorylation motifs are mostly disordered. However, human cancer mutations within phosphorylation motifs tend to decrease the disorder propensity. Our results suggest that combination of acidic residues Asp and Glu with phosphorylation sites provide charge redundancy which may safe guard against loss-of-function mutations, and that the natively disordered nature of p53 phosphorylation motifs may help reduce mutational damage. Our results further suggest that engineering acidic amino acids adjacent to potential phosphorylation sites could be a p53 gene therapy strategy.

  2. Optimized p53 immunohistochemistry is an accurate predictor of TP53 mutation in ovarian carcinoma.

    PubMed

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

    2016-10-01

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

  3. p53 mutations in leukemia and myelodysplastic syndrome after ovarian cancer.

    PubMed

    Leonard, Debra G B; Travis, Lois B; Addya, Kathakali; Dores, Graca M; Holowaty, Eric J; Bergfeldt, Kjell; Malkin, David; Kohler, Betsy A; Lynch, Charles F; Wiklund, Tom; Stovall, Marilyn; Hall, Per; Pukkala, Eero; Slater, Diana J; Felix, Carolyn A

    2002-05-01

    Although p53 mutations occur in alkylating agent-related leukemias, their frequency and spectrum in leukemias after ovarian cancer have not been addressed. The purpose of this study was to examine p53 mutations in leukemias after ovarian cancer, for which treatment with platinum analogues was widely used. Adequate leukemic or dysplastic cells were available in 17 of 82 cases of leukemia or myelodysplastic syndrome that occurred in a multicenter, population-based cohort of 23,170 women with ovarian cancer. Eleven of the 17 received platinum compounds and other alkylating agents with or without DNA topoisomerase II inhibitors and/or radiation. Six received other alkylating agents, in one case, with radiation. Genomic DNA was extracted and p53 exons 5, 6, 7, and 8 were amplified by PCR. Mutations and loss of heterozygosity were analyzed on the WAVE instrument (Transgenomic) followed by selected analysis by sequencing. Eleven p53 mutations involving all four exons studied and one polymorphism were identified. Genomic DNA analyses were consistent with loss of heterozygosity for four of the mutations. The 11 mutations occurred in 9 cases, such that 6 of 11 leukemias after platinum-based regimens (55%) and 3 of 6 leukemias after other treatments (50%) contained p53 mutations. Two leukemias that occurred after treatment with platinum analogues contained two mutations. Among eight mutations in leukemias after treatment with platinum analogues, there were four G-to-A transitions and one G-to-C transversion. p53 mutations are common in leukemia and myelodysplastic syndrome after multiagent therapy for ovarian cancer. The propensity for G-to-A transitions may reflect specific DNA damage in leukemias after treatment with platinum analogues.

  4. Alternate splicing of the p53 inhibitor HDMX offers a superior prognostic biomarker than p53 mutation in human cancer.

    PubMed

    Lenos, Kristiaan; Grawenda, Anna M; Lodder, Kirsten; Kuijjer, Marieke L; Teunisse, Amina F A S; Repapi, Emmanouela; Grochola, Lukasz F; Bartel, Frank; Hogendoorn, Pancras C W; Wuerl, Peter; Taubert, Helge; Cleton-Jansen, Anne-Marie; Bond, Gareth L; Jochemsen, Aart G

    2012-08-15

    Conventional high-grade osteosarcoma is the most common primary bone malignancy. Although altered expression of the p53 inhibitor HDMX (Mdmx/Mdm4) is associated with cancer risk, progression, and outcome in other tumor types, little is known about its role in osteosarcoma. High expression of the Hdmx splice variant HDMX-S relative to the full-length transcript (the HDMX-S/HDMX-FL ratio) correlates with reduced HDMX protein expression, faster progression, and poorer survival in several cancers. Here, we show that the HDMX-S/HDMX-FL ratio positively correlates with less HDMX protein expression, faster metastatic progression, and a trend to worse overall survival in osteosarcomas. We found that the HDMX-S/HDMX-FL ratio associated with common somatic genetic lesions connected with p53 inhibition, such as p53 mutation and HDM2 overexpression in osteosarcoma cell lines. Interestingly, this finding was not limited to osteosarcomas as we observed similar associations in breast cancer and a variety of other cancer cell lines, as well as in tumors from patients with soft tissue sarcoma. The HDMX-S/HDMX-FL ratio better defined patients with sarcoma with worse survival rates than p53 mutational status. We propose a novel role for alternative splicing of HDMX, whereby it serves as a mechanism by which HDMX protein levels are reduced in cancer cells that have already inhibited p53 activity. Alternative splicing of HDMX could, therefore, serve as a more effective biomarker for p53 pathway attenuation in cancers than p53 gene mutation.

  5. A Novel Radiation-Induced p53 Mutation Is Not Implicated in Radiation Resistance via a Dominant-Negative Effect

    PubMed Central

    Sun, Yunguang; Myers, Carey Jeanne; Dicker, Adam Paul; Lu, Bo

    2014-01-01

    Understanding the mutations that confer radiation resistance is crucial to developing mechanisms to subvert this resistance. Here we describe the creation of a radiation resistant cell line and characterization of a novel p53 mutation. Treatment with 20 Gy radiation was used to induce mutations in the H460 lung cancer cell line; radiation resistance was confirmed by clonogenic assay. Limited sequencing was performed on the resistant cells created and compared to the parent cell line, leading to the identification of a novel mutation (del) at the end of the DNA binding domain of p53. Levels of p53, phospho-p53, p21, total caspase 3 and cleaved caspase 3 in radiation resistant cells and the radiation susceptible (parent) line were compared, all of which were found to be similar. These patterns held true after analysis of p53 overexpression in H460 cells; however, H1299 cells transfected with mutant p53 did not express p21, whereas those given WT p53 produced a significant amount, as expected. A luciferase assay demonstrated the inability of mutant p53 to bind its consensus elements. An MTS assay using H460 and H1299 cells transfected with WT or mutant p53 showed that the novel mutation did not improve cell survival. In summary, functional characterization of a radiation-induced p53 mutation in the H460 lung cancer cell line does not implicate it in the development of radiation resistance. PMID:24558369

  6. Heterozygous p53V172F mutation in cisplatin-resistant human tumor cells promotes MDM4 recruitment and decreases stability and transactivity of p53

    PubMed Central

    Xie, Xiaolei; Lozano, Guillermina; Siddik, Zahid H.

    2017-01-01

    Cisplatin is an important antitumor agent, but its clinical utility is often limited by multifactorial mechanism of resistance. Loss of tumor suppressor p53 function is a major mechanism, affected by either mutation in the DNA binding domain or dysregulation by overexpression of p53 inhibitors MDM2 and MDM4 that destabilize p53 by increasing its proteosomal degradation. In the present study, cisplatin-resistant 2780CP/Cl-16 ovarian tumor cells expressed a heterozygous, temperature-sensitive p53V172F mutation, which reduced p53 half-life by 2- to 3-fold compared to homozygous wild-type p53 in parental A2780 cells. Although reduced p53 stability in 2780CP/Cl-16 cells was associated with moderate cellular overexpression of MDM2 or MDM4 (<1.5-fold), their binding to p53 was substantially enhanced (5- to 8-fold). The analogous cisplatin-resistant 2780CP/Cl-24 cells, which express loss of p53 heterozygosity, retained the p53V172F mutation and high p53-MDM4 binding, but demonstrated lower p53-bound MDM2 that was associated with reduced p53 ubiquitination and enhanced p53 stability. The inference that p53 was unstable as a hetromeric p53wt/p53V172F complex was confirmed in 2780CP/Cl-24 cells transfected with wild-type (wt) p53 or multimer-inhibiting p53L344P mutant, and further supported by normalization of p53 stability in both resistant cell lines grown at the permissive temperature of 32.5°C. Surprisingly, in 2780CP/Cl-16 and 2780CP/Cl-24 models, cisplatin-induced transactivity of p53 was attenuated at 37°C, and this correlated with cisplatin resistance. However, downregulation of MDM2 or MDM4 by siRNA in either resistant cell line induced p53 and restored p21 transactivation at 37°C, as did cisplatin-induced DNA damage at 32.5°C that coincided with reduced p53-MDM4 binding and cisplatin resistance. These results demonstrate that cisplatin-mediated p53V172F mutation regulates p53 stability at the normothermic temperature, but it is the increased recruitment of MDM4

  7. Mutations in the p53 and Ki-ras genes, microsatellite instability and site of tumor origin in colorectal cancer.

    PubMed

    Catalano, Teresa; Curia, Maria Cristina; Aceto, Gitana; Verginelli, Fabio; Cascinu, Stefano; Cama, Alessandro; Mariani-Costantini, Renato; Teti, Diana; Battista, Pasquale

    2005-09-01

    Using PCR-SSCP screening and direct sequencing we analyzed a series of 28 colorectal carcinomas for mutations in p53 (exons 5-8) and Ki-ras (codons 12, 13 and 61), and for micro-satellite instability (MSI) at BAT25 and BAT26, supplementing data with the analysis of the IARC colorectal cancer p53 mutation database. Mutations were correlated with the site of tumor origin (proximal or distal to the splenic flexure). We identified 19 mutations in p53, 9 in Ki-ras, and 4 MSI-positive cases in a total of 20 tumors. Only 6/20 cases (30%) carried mutations in both p53 and Ki-ras. Mutations in p53 were detected at similar frequencies in proximal and distal tumors, while IARC data pointed to a strong association of p53 mutations with distal cancers. Ki-ras mutations were more frequent in proximal tumors, and MSI occurred at similar frequencies in proximal and distal tumors and was associated with mutations in p53 or Ki-ras. The p53 mutations detected in the series analyzed, as well as those retrieved from the IARC database, were predominantly transitions, with no preferential sequence localization or nucleotide position. Ki-ras mutations were predominantly transversions in position 2 at codon 12. MSI-H occurred at similar frequencies in proximal and distal tumors and was associated with either p53 or Ki-ras mutations. Overall these data suggest that distinct mutagenic factors target p53 and Ki-ras in colorectal epithelium irrespective of MSI-H status.

  8. Unequal prognostic potentials of p53 gain-of-function mutations in human cancers associate with drug-metabolizing activity.

    PubMed

    Xu, J; Wang, J; Hu, Y; Qian, J; Xu, B; Chen, H; Zou, W; Fang, J-Y

    2014-03-06

    Mutation of p53 is the most common genetic change in human cancer, causing complex effects including not only loss of wild-type function but also gain of novel oncogenic functions (GOF). It is increasingly likely that p53-hotspot mutations may confer different types and magnitudes of GOF, but the evidences are mainly supported by cellular and transgenic animal models. Here we combine large-scale cancer genomic data to characterize the prognostic significance of different p53 mutations in human cancers. Unexpectedly, only mutations on the Arg248 and Arg282 positions displayed significant association with shorter patient survival, but such association was not evident for other hotspot GOF mutations. Gene set enrichment analysis on these mutations revealed higher activity of drug-metabolizing enzymes, including the CYP3A4 cytochrome P450. Ectopic expression of p53 mutant R282W in H1299 and SaOS2 cells significantly upregulated CYP3A4 mRNA and protein levels, and cancer cell lines bearing mortality-associated p53 mutations display higher CYP3A4 expression and resistance to several CYP3A4-metabolized chemotherapeutic drugs. Our results suggest that p53 mutations have unequal GOF activities in human cancers, and future evaluation of p53 as a cancer biomarker should consider which mutation is present in the tumor, rather than having comparison between wild-type and mutant genotypes.

  9. p53 mutations in human lymphoid malignancies: Association with Burkitt lymphoma and chronic lymphocytic leukemia

    SciTech Connect

    Gaidano, G.; Ballerini, P.; Gong, J.Z.; Inghirami, G.; Knowles, D.M.; Dalla-Favera, R. ); Neri, A, Centro Malattie del Sangue G. Marcora, Milan ); Newcomb, E.W. ); Magrath, I.T. )

    1991-06-15

    The authors have investigated the frequency of p53 mutations in B- and T-cell human lymphoid malignancies, including acute lymphoblastic leukemia, the major subtypes of non-Hodgkin lymphoma, and chronic lymphocytic leukemia. p53 exons 5-9 were studied by using genomic DNA from 197 primary tumors and 27 cell lines by single-strand conformation polymorphism analysis and by direst sequencing of PCR-amplified fragments. Mutations were found associated with (i) Burkitt lymphoma (9/27 biopsoes; 17/27 cell lines) and its leukemic counterpart L{sub 3}-type B-cell acute lymphoblastic leukemia (5/9), both of which also carry activated c-myc oncogenes, and (ii) B-cell chronic lymphocytic leukemia (6/40) and, in particular, its stage of progression known as Richter's transformation (3/7). Mutations were not found at any significant frequency in other types of non-Hodgkin lymphoma or acute lymphoblastic leukemia. In many cases, only the mutated allele was detectable, implying loss of the normal allele. These results suggest that (1) significant differences in the frequency of p53 mutations are present among subtypes of neoplasms derived from the same tissue; (2) p53 may play a role in tumor progression in B-cell chronic lymphocytic leukemia; (3) the presence of both p53 loss/inactivation and c-myc oncogene activation may be important in the pathogenesis of Burkitt lymphoma and its leukemia form L{sub 3}-type B-cell acute lymphoblastic leukemia.

  10. p53 mutation is common in microsatellite stable, BRAF mutant colorectal cancers.

    PubMed

    Bond, Catherine E; Umapathy, Aarti; Ramsnes, Ingunn; Greco, Sonia A; Zhen Zhao, Zhen; Mallitt, Kylie-Ann; Buttenshaw, Ron L; Montgomery, Grant W; Leggett, Barbara A; Whitehall, Vicki L J

    2012-04-01

    The majority of "serrated pathway" colorectal cancers have mutation of the BRAF oncogene and display the CpG island methylator phenotype (CIMP). Half these cancers have microsatellite instability (MSI) and an excellent prognosis. In the absence of MSI (microsatellite stable, MSS), BRAF mutation has been associated with a particularly poor prognosis. "Traditional pathway" cancers are BRAF wild type. Mutation of p53 is common and this correlates with advanced stage. We therefore hypothesized that p53 mutation would be common in MSS/BRAF mutant colorectal cancer. One thousand and eighty-one colorectal cancers were screened for BRAF mutation to identify two BRAF mutant study groups (MSI: n = 77; MSS: n = 69) and a BRAF wild type control group (n = 101). These were screened for p53 mutation by high resolution melt analysis and classified for CIMP and MGMT methylation by quantitative methylation specific PCR. Molecular data were compared to patient age, gender, tumor location and stage. p53 was mutated significantly more frequently in MSS/BRAF mutant (28/69, 40.6%) compared to MSI/BRAF mutant cancers (13/77, 16.9%), but this mutation rate did not differ from MSS/BRAF wild type cancers (47/101, 46.5%)(p < 0.0001). CIMP was less common in MSS/BRAF mutant (26/47, 55.3%) compared to MSI/BRAF mutant cancers (41/54, 75.9%), but was more common than in MSS/BRAF wild type cancers (3/85, 3.5%) (p < 0.0001). MSS/BRAF mutant cancers were more commonly proximal (38/54, 70.3%), but were similar to MSS/BRAF wild type cancers in terms of patient age, gender distribution and stage at presentation. MSS/BRAF mutant cancers share molecular and clinical features of both the serrated and traditional pathways of colorectal tumorigenesis.

  11. Centrosome Hypertrophy Induced by p53 Mutations Leads to Tumor Aneuploidy

    DTIC Science & Technology

    2002-06-01

    Hypertrophy Induced by p53 Mutations Leads to Tumor Aneuploidy PRINCIPAL INVESTIGATOR: Wilma L. Lingle, Ph.D. CONTRACTING ORGANIZATION: Mayo Foundation...p 5 3 Mutations DAMD17-98-1-8122 Leads to Tumor Aneuploidy 6. AUTHOR(S) Wilma L. Lingle, Ph.D. 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8... tumors is caused by centrosome abnormalities which are induced by alteration in p53 function. Specific mutations in p53 that are associated with breast

  12. p53 exon 7 mutations as a predictor of poor prognosis in patients with colorectal cancer.

    PubMed

    Iniesta, P; Vega, F J; Caldés, T; Massa, M; de Juan, C; Cerdán, F J; Sánchez, A; López, J A; Torres, A J; Balibrea, J L; Benito, M

    1998-08-14

    We have studied 61 resected colorectal adenocarcinomas in order to investigate p53 mutations as a prognostic factor for this pathology. Mutations in exons 5-9 of the p53 gene were analyzed by the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique followed by sequencing. Our data indicate that p53 exon 7 mutations were prevalent in the latest stages of colorectal carcinogenesis and patients bearing this alteration had the worst prognosis. Therefore, according to our results, mutations affecting exon 7 of the p53 gene could be considered as a useful marker of biological aggressiveness for colorectal cancer.

  13. Somatic point mutations in the p53 gene of human tumors and cell lines: updated compilation.

    PubMed

    Hollstein, M; Shomer, B; Greenblatt, M; Soussi, T; Hovig, E; Montesano, R; Harris, C C

    1996-01-01

    In 1994 we described a list of approximately 2500 point mutations in the p53 gene of human tumors and cell lines which we had compiled from the published literature and made available electronically through the file server at the EMBL Data Library. This database, updated twice a year, now contains records on 4496 published mutations (July 1995 release) and can be obtained from the EMBL Outstation-the European Bioinformatics Institute (EBI) through the network or on CD-ROM. This report describes the criteria for inclusion of data in this database, a description of the current format and a brief discussion of the current relevance of p53 mutation analysis to clinical and biological questions.

  14. Mutations of the p53 gene in human functional adrenal neoplasms

    SciTech Connect

    Shiu-Ru Lin; Yau-Jiunn Lee; Juei-Hsiung Tsai

    1994-02-01

    To clarify gene alterations in functional human adrenal tumors, the authors performed molecular analysis for p53 abnormalities in 23 cases with adrenal neoplasms. The immunohistochemical study with anti-p53 monoclonal antibody pAb1801 demonstrated that 10 of 23 (43.5%) cases overexpressed p53 protein in the tumor cells. Using a polymerase chain reaction-single strand conformation polymorphism study, 5 of 6 (83.3%) pheochromocytoma tissues (1 malignant and 5 benign) and 11 of 15 (73.3%) adrenocortical adenomas (2 with Cushing`s syndrome and 13 with primary aldosteronism, all benign) showed an apparent electrophoretic mobility shift between the tumor and its paired adjacent normal adrenal tissue. Such differences were detected in exon 4 (12 cases), exon 5 (2 cases), and exon 7 (3 cases). The types of these mutations in exon 4 were a substitution from threonine (ACC) to isoleucine (ATC) at codon 102 in 5 cases, from glutamine (CAG) to histidine (CAC) at codon 104 in 1 case, from glycine (GGG) to alanine (CGG) at codon 117 in 1 case, from glutamate (GAG) to glutamine (CAG) at codon 68 in 1 case, and single base changes resulting in a premature stop codon at codon 100 in 2 cases. A 2-basepair deletion at codon 175 in exon 5 resulting in a frame shift was identified in 1 case. A single point mutation was identified, resulting in the substitution of glutamine (CAG) for arginine (CGG) at codon 248 of exon 7 in 1 case. A single basepair deletion at codon 249 resulted in a frame shift in 2 cases. There was 1 case with malignant pheochromocytoma that combined a single point mutation in exon 4 and a single base deletion in exon 7. Only 2 of 23 cases showed a loss of a normal allele encoding in the p53 gene. Northern blot analysis with 1.8-kilobase p53 cDNA revealed that p53 mRNA was overexpressed in 6 cases. The results indicate that high frequencies of p53 gene mutation, especially in exon 4, exist in functional adrenal tumors. 39 refs., 6 figs., 4 tabs.

  15. 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.

  16. Effect of FHIT loss and p53 mutation on HPV-infected lung carcinoma development.

    PubMed

    Yu, Yan; Liu, Xiaofei; Yang, Yuxuan; Zhao, Xiaodan; Xue, Jianjun; Zhang, Weixiao; Yang, Aimin

    2015-07-01

    High-risk human papillomavirus (HPV)16/18 infection in the development of lung cancer has previously been identified, and fragile histidine triad (FHIT) loss and p53 mutation are frequently observed in the disease. However, the association between these factors has not been well studied. The present study aimed to further investigate the significance of HPV infection, FHIT loss and p53 mutations in the development of lung cancer and their possible associations. DNA was extracted from paraffin-embedded specimens from 88 cases of squamous cell carcinoma (SCC), 56 of adenocarcinoma (AC), 36 of small cell lung carcinoma (SCLC) and 110 non-cancer control cases of lung neoplasms. The prevalence of HPV infection was determined by polymerase chain reaction analysis, and FHIT loss and p53 mutations were detected by immunohistochemistry. The χ(2), Fisher's exact and Pearson correlation tests were applied for statistical analysis. The results of the present study demonstrated that HPVL1 (the major capsid protein of HPV), HPV16 and HPV18 infection were more prevalent in the lung cancer samples compared with the non-cancer controls (all P<0.001). FHIT loss occurred more frequently in the lung cancer samples (44.44%) compared with the non-cancer controls (7.25%) (P<0.001). FHIT loss in the HPVL1-positive group was significantly increased compared with the HPVL1-negative group in the lung cancer cases and the non-cancer controls (P<0.05). In the lung cancer cases, the p53 mutation rates in the HPVL1- and HPV16/18-positive groups were significantly increased compared with the HPVL1- and HPV16/18-negative groups (P<0.05). In the 180 lung cancer cases, the coexistence rate of FHIT loss and a history of smoking was 38.33% (69/180; Pearson contingency coefficient of r=0.318; P<0.001). FHIT loss and p53 mutation exhibited a synergistic effect on HPV-associated lung cancer (Pearson contingency coefficient r=0.357, P<0.001). The present study demonstrated that FHIT loss may be important

  17. Clonal expansion to anaplasia in Wilms` tumors is associated with p53 mutations

    SciTech Connect

    Pelletier, J.; Beckwith, B.; Bardeesy, N. |

    1994-09-01

    The genetics of Wilms` tumor (WT), a pediatric malignancy of the kidney, is complex. Three loci are implicated in WT initiation and include the WT1 tumor suppressor gene (residing at 11p13), an 11p15 locus, and a non-11p locus. As well, allelic loss at 16q24 in {approximately}20% of sporadic WTs suggests the location of (an) additional gene(s) involved in tumor progression. Initiation and progression in WTs is associated with multiple histological variants. Anaplasia is a rare WT subtype associated with poor prognosis and defined by enlarged and multipolar mitotic figures, a threefold nuclear enlargement (compared with adjacent nuclei of the same cell type), and hyperchromasia of the enlarged nuclei. We have previously demonstrated that p53 gene mutations are exclusively associated with anaplastic WTs, being absent from a large number of non-anaplastic WTs analyzed. To determine if such mutations are involved in clonal progression to anaplasia, we performed a retrospective analysis of histologically defined sections from tumor specimens. Six of ten WTs demonstrated p53 mutations by PCR-single stranded conformational polymorphism analysis. Two of these samples were paired, consisting of geographically demarcated anaplastic cells embedded within a non-anaplastic tumor bed. In these cases, p53 mutations were only present in the anaplastic region of the tumor. An overall decrease in the number of apoptotic cells was found associated with the anaplastic tumor region, compared to adjacent non-anaplastic tumor bed. These results indicate that p53 mutations arise during progression to anaplasia late in Wilms` tumor etiology and are associated with a more aggressive form of this cancer.

  18. SIRT1 inhibition restores apoptotic sensitivity in p53-mutated human keratinocytes.

    PubMed

    Herbert, Katharine J; Cook, Anthony L; Snow, Elizabeth T

    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-mutated (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.

  19. In situ detection of specific p53 mutations in cultured cells using the amplification refractory mutation system polymerase chain reaction.

    PubMed

    Low, E O; Gibbins, J R; Walker, D M

    2000-12-01

    Accurate molecular detection of genetic mutations involved in tumorigenesis has been based predominantly on analysis of extracted DNA, but this does not provide detailed information on the location, number, type or clonal distribution of mutated cells and their precise anatomic location and clonal distribution. This study has used a sensitive and specific application of the amplification refractory mutation system (ARMS)-polymerase chain reaction (PCR) in situ, combined with in situ hybridization to localize and identify cells with defined p53 mutations. The ARMS-PCR was performed in situ in SW480 cells in suspension and in cells either cultured or cytospun onto glass slides. Amplified mutant DNA PCR products were detected in SW480 cells using digoxigenin-labeled probes, visually identifying cells harboring specific mutations in the p53 gene. In situ hybridization alone of the mutant cells without the amplification step was negative. Normal human fibroblasts or endothelial cells were refractory to in situ amplification. This reaction was mutation-specific as CEM cells with different p53 mutations reacted negatively. Mutant messenger RNA (mRNA) in tumor cells was also selectively amplified in situ by ARMS-PCR following reverse transcription (RT). This study demonstrates the potential of in situ ARMS-PCR or RT-ARMS-PCR for mutation analysis in situ and could have useful clinical applications.

  20. Correlation of mutation and immunohistochemistry of p53 in hepatocellular carcinomas in Korean people.

    PubMed Central

    Lee, Shi Nae; Park, Cheol Keun; Sung, Chang Ohk; Choi, Jong Sun; Oh, Young Lyun; Cho, Jae Won; Yoo, Byung Chul

    2002-01-01

    The degree of correlation between sequencing and immunohistochemisty (IHC) for detecting mutations of p53 has not been well established in human hepatocellular carcinoma (HCC). We analyzed 36 HCCs from Korean people for p53 mutation at exons 4-10 by PCR-SSCP and sequencing, and compared the results with the IHC positivity. p53 mutations were identified in 7 out of 36 HCCs (19.4%). These mutations were found widely throughout exons 4-8. No mutation was detected in codon 249. Among the 7 mutations, 6 missense mutations were detected in 15 HCCs with > or =5% immunoreactive tumor cells and one nonsense mutation was in 21 HCCs with <5% immunoreactive tumor cells. The sensitivity for p53 mutation was 85.7% (6/7), the specificity 69.0% (20/29), the predictive value of positive IHC 40.0% (6/15), and the predictive value of negative IHC 95.2% (20/21). Two missense mutations were detected in 25 cases with <10% immunoreactive tumor cells. Predictive values of both positive IHC and negative IHC were higher in > or =5% overexpression group than in > or =10% overexpression group or >0% overexpression group. This study suggests that 5% immunoreactivity is a reliable immunohistochemical threshold value to detect p53 mutations in HCCs and the spectrum of p53 mutations in HCCs in Korean people is different from that of high aflatoxin B1 exposure areas. PMID:12483005

  1. Mutation of Lkb1 and p53 genes exert a cooperative effect on tumorigenesis.

    PubMed

    Wei, Chongjuan; Amos, Christopher I; Stephens, L Clifton; Campos, Imelda; Deng, Jian Min; Behringer, Richard R; Rashid, Asif; Frazier, Marsha L

    2005-12-15

    Peutz-Jeghers syndrome (PJS) is a dominantly inherited disorder characterized by gastrointestinal hamartomatous polyps and mucocutaneous melanin pigmentation. Germ line mutations in LKB1 cause PJS. We have generated mice carrying an Lkb1 exon 2 to 8 deletion by gene targeting in embryonic stem cells. Heterozygotes develop gastric hamartomas that are histologically similar to those found in humans with PJS. LKB1 is also reportedly a mediator of p53-dependent apoptosis. To explore the potential combined effects of p53 and Lkb1 alterations on tumorigenesis, we carried out a series of matings with Lkb1(+/-) and p53 null mice to generate Lkb1(+/-)/p53(+/-) and Lkb1(+/-)/p53(-/-) mice. Similar to the Lkb1(+/-) mice, gastrointestinal hamartomas have also been detected in the mice with these two genotypes. The Lkb1(+/-)/p53(+/-) mice displayed a dramatically reduced life span and increased tumor incidence compared to the mice with either Lkb1 or p53 single gene knockout. The time to onset of polyposis in Lkb1(+/-)/p53(-/-) mice is approximately 2 months earlier than Lkb1(+/-)/p53(+/-) and Lkb1(+/-) mice, whereas the latter two show a similar time to onset which is at approximately 6 months of age. These results strongly suggested that mutations of p53 and Lkb1 gene cooperate in the acceleration of tumorigenesis.

  2. SIRT1 inhibition restores apoptotic sensitivity in p53-mutated human keratinocytes

    SciTech Connect

    Herbert, Katharine J.; Cook, Anthony L. Snow, Elizabeth T.

    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-mutated (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.

  3. p53 Mutations in human adrenocortical neoplasms: Immunohistochemical and molecular studies

    SciTech Connect

    Reincke, M.; Allolio, B.; Travis, W.H.; Linehan, H.M.; Karl, M.; Mastorakos, G.; Chrousos, G.P.

    1994-03-01

    p53 is a recessive tumor suppressor gene located on chromosome 17p. Mutations in the p53 gene play an important role in the tumorigenesis of diverse types of human neoplasms including breast and colon cancers. More than 90% of all mutations discovered in such tumors have been detected in 4 hot spot areas that lie between exons 5 and 8. In contrast to wild-type p53, mutant p53 accumulates intracellularly and can be easily detected by immunohistochemistry. The authors therefore investigated the frequency of p53 mutations in human adrenocortical neoplasms using molecular biology and immunohistochemistry techniques. Five patients with adrenocortical adenomas (5 female; ages 39-72 yr), 11 patients with adrenocortical carcinomas (8 female, 3 male; ages 15-50 yr), and two adrenocortical tumor cell lines were studied. After DNA extraction from frozen tumor tissue or paraffin-embedded material, exons 5 through 8 were amplified using the polymerase chain reaction and directly sequenced by the dideoxy termination method. Immunohistochemistry was performed on paraffin-embedded tumor specimens obtained during adrenalectomy using a monoclonal antibody reacting with both wild-type and mutant p53. Prevalence of mutations was adenomas, 0/5, carcinomas, 3/11, and adrenocortical cell lines, 2/2. Single point mutations were detected in 3 cases (exons 5, 6, and 7, respectively), and rearrangements of exon 7/8 and 8 were found in 2 cases. Immunohistochemistry detected strong nuclear and/or cytoplasmic p53 immunoreactivity in all adrenocortical carcinomas with point mutations of the p53 gene but not in adenomas and carcinomas with the wild-type sequence or with deletion/rearrangement of the p53 gene. They conclude that p53 plays a role in the tumorigenesis of adrenocortical carcinomas but is of less importance to benign adenomas. 27 refs., 3 figs., 2 tabs.

  4. Ameloblastic carcinoma developing in preexisting ameloblastoma with a mutation of the p53 gene: a case report.

    PubMed

    Nobusawa, Aiko; Sano, Takaaki; Yokoo, Satoshi; Oyama, Tetsunari

    2014-11-01

    Ameloblastic carcinoma is a rare malignant odontogenic tumor. Here we present a case of a large ameloblastic carcinoma, which developed in a preexisting ameloblastoma in the right submandibular region. The patient was an 84-year-old woman who had received several surgical procedures for ameloblastoma, including a segmental mandibulectomy. The dimensions of the tumor were 12 × 8 × 5 cm, and both benign ameloblastoma and ameloblastic carcinoma were observed histologically. Based on histologic diagnosis, immunohistochemical staining and sequence analysis for p53 were performed. Overexpression of p53 was observed only in the ameloblastic carcinoma. Additionally, a mutation of the p53 gene (TP53) in exon 5 was found by sequence analysis in the ameloblastic carcinoma. This is the first case of ameloblastic carcinoma with a mutation of the p53 gene that has been associated with carcinomatous transformation. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Evaluating Drosophila p53 as a model system for studying cancer mutations.

    PubMed

    Herzog, Gal; Joerger, Andreas C; Shmueli, Merav D; Fersht, Alan R; Gazit, Ehud; Segal, Daniel

    2012-12-28

    The transcription factor p53 is a key tumor suppressor protein. In about half of human cancers, p53 is inactivated directly through mutation in its sequence-specific DNA-binding domain. Drosophila p53 (Dmp53) has similar apoptotic functions as its human homolog and is therefore an attractive model system for studying cancer pathways. To probe the structure and function of Dmp53, we studied the effect of point mutations, corresponding to cancer hot spot mutations in human p53 (Hp53), on the stability and DNA binding affinity of the full-length protein. Despite low sequence conservation, the Hp53 and Dmp53 proteins had a similar melting temperature and generally showed a similar energetic and functional response to cancer-associated mutations. We also found a correlation between the thermodynamic stability of the mutant proteins and their rate of aggregation. The effects of the mutations were rationalized based on homology modeling of the Dmp53 DNA-binding domain, suggesting that the drastically different effects of a cancer mutation in the loop-sheet-helix motif (R282W in Hp53 and R268W in Dmp53) on stability and DNA binding affinity of the two proteins are related to conformational differences in the L1 loop adjacent to the mutation site. On the basis of these data, we discuss the advantages and limitations of using Dmp53 as a model system for studying p53 function and testing p53 rescue drugs.

  6. The incidence of p53 mutations increases with progression of head and neck cancer.

    PubMed

    Boyle, J O; Hakim, J; Koch, W; van der Riet, P; Hruban, R H; Roa, R A; Correo, R; Eby, Y J; Ruppert, J M; Sidransky, D

    1993-10-01

    To establish a genetic model of the progression of head and neck squamous carcinoma we have defined the incidence and timing of p53 mutations in this type of cancer. We sequenced the conserved regions of the p53 gene in 102 head and neck squamous carcinoma lesions. These included 65 primary invasive carcinomas and 37 noninvasive archival specimens consisting of 13 severe dysplasias and 24 carcinoma in situ lesions. The incidence of p53 mutations in noninvasive lesions was 19% (7/37) and increased to 43% (28/65) in invasive carcinomas. These data suggest that p53 mutations can precede invasion in primary head and neck cancer. Furthermore, the spectrum of codon hotspots is similar to that seen in squamous carcinoma of the lung and 64% of mutations are at G nucleotides, implicating carcinogens from tobacco smoke in the etiology of head and neck squamous carcinoma.

  7. Frequent p53 gene mutations in soft tissue sarcomas arising in burn scar.

    PubMed

    Nakanishi, H; Tomita, Y; Yoshikawa, H; Sato, N; Ochi, T; Aozasa, K

    1999-03-01

    Squamous cell carcinoma (SCC) is the commonest malignancy that arises in burn scars, which frequently contain p53 mutations. Soft tissue sarcoma (STS) also develops, though less frequently, in burn scars. p53 gene mutations were analyzed in paraffin-embedded specimens from 5 patients with STS (4 males and 1 female) that had arisen in a burn scar, by means of polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) followed by direct sequencing. Age at burn injury ranged from 2 to 10 (median 3) years, and STS developed with a latent period ranging from 29 to 79 (median 60) years. Histologically, all were malignant fibrous histiocytoma. The PCR-SSCP revealed aberrant bands in 4 (80%) of 5 cases. Direct sequencing revealed a total of 11 mutations in these 4 cases: 1 case had a single mutation, 1 had 2 mutations, and 2 had 4 mutations. Every tumor had at least 1 mutation that changed an amino acid, which may have provided the selection pressure for expansion. Thus, there is a high frequency of p53 gene mutations in STS appearing in burn scars. p53 mutations were also frequent in pyothorax-associated lymphoma (PAL), a lymphoma that develops in patients with long-standing pyothorax, so p53 mutations might be frequent in malignancies that develop in chronic inflammatory sites.

  8. Divergence between the high rate of p53 mutations in skin carcinomas and the low prevalence of anti-p53 antibodies

    PubMed Central

    Moch, C; Moysan, A; Lubin, R; Salmonière, P de La; Soufir, N; Galisson, F; Vilmer, C; Venutolo, E; Pelletier, F Le; Janin, A; Basset-Séguin, N

    2001-01-01

    Circulating anti-p53 antibodies have been described and used as tumoural markers in patients with various cancers and strongly correlate with the p53 mutated status of the tumours. No study has yet looked at the prevalence of such antibodies in skin carcinoma patients although these tumours have been shown to be frequently p53 mutated. Most skin carcinoma can be diagnosed by examination or biopsy, but aggressive, recurrent and/or non-surgical cases' follow up would be helped by a biological marker of residual disease. We performed a prospective study looking at the prevalence of anti-p53 antibodies using an ELISA technique in a series of 105 skin carcinoma patients in comparison with a sex- and age-matched control skin carcinoma-free group (n = 130). Additionally, p53 accumulation was studied by immunohistochemistry to confirm p53 protein altered expression in a sample of tumours. Anti-p53 antibodies were detected in 2.9% of the cases, with a higher prevalence in patients suffering from the more aggressive squamous cell type (SCC) of skin carcinoma (8%) than for the more common and slowly growing basal cell carcinoma type or BCC (1.5%). p53 protein stabilization could be confirmed in 80% of tumours studied by IHC. This low level of anti-p53 antibody detection contrasts with the high rate of p53 mutations reported in these tumours. This observation shows that the anti-p53 humoral response is a complex and tissue-specific mechanism. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11747330

  9. p53 mutations associated with aging-related rise in cancer incidence rates.

    PubMed

    Richardson, Richard B

    2013-08-01

    TP53's role as guardian of the genome diminishes with age, as the probability of mutation increases. Previous studies have shown an association between p53 gene mutations and cancer. However, the role of somatic TP53 mutations in the steep rise in cancer rates with aging has not been investigated at a population level. This relationship was quantified using the International Agency for Research on Cancer (IARC) TP53 and GLOBOCAN cancer databases. The power function exponent of the cancer rate was calculated for 5-y age-standardized incidence or mortality rates for up to 25 cancer sites occurring in adults of median age 42 to 72 y. Linear regression analysis of the mean percentage of a cancer's TP53 mutations and the corresponding cancer exponent was conducted for four populations: worldwide, Japan, Western Europe, and the United States. Significant associations (P ≤ 0.05) were found for incidence rates but not mortality rates. Regardless of the population studied, positive associations were found for all cancer sites, with more significant associations for solid tumors, excluding the outlier prostate cancer or sex-related tumors. Worldwide and Japanese populations yielded P values as low as 0.002 and 0.005, respectively. For the United States, a significant association was apparent only when analysis utilized the Surveillance, Epidemiology, and End Results (SEER) database. This study found that TP53 mutations accounts for approximately one-quarter and one-third of the aging-related rise in the worldwide and Japanese incidence of all cancers, respectively. These significant associations between TP53 mutations and the rapid rise in cancer incidence with aging, considered with previously published literature, support a causal role for TP53 according to the Bradford-Hill criteria. However, questions remain concerning the contribution of TP53 mutations to neoplastic development and the role of factors such as genetic instability, obesity, and gene deficiencies other

  10. Ribosomal Protein Mutations Result in Constitutive p53 Protein Degradation through Impairment of the AKT Pathway

    PubMed Central

    Hermkens, Dorien; Wlodarski, Marcin W.; Da Costa, Lydie; MacInnes, Alyson W.

    2015-01-01

    Mutations in ribosomal protein (RP) genes can result in the loss of erythrocyte progenitor cells and cause severe anemia. This is seen in patients with Diamond-Blackfan anemia (DBA), a pure red cell aplasia and bone marrow failure syndrome that is almost exclusively linked to RP gene haploinsufficiency. While the mechanisms underlying the cytopenia phenotype of patients with these mutations are not completely understood, it is believed that stabilization of the p53 tumor suppressor protein may induce apoptosis in the progenitor cells. In stark contrast, tumor cells from zebrafish with RP gene haploinsufficiency are unable to stabilize p53 even when exposed to acute DNA damage despite transcribing wild type p53 normally. In this work we demonstrate that p53 has a limited role in eliciting the anemia phenotype of zebrafish models of DBA. In fact, we find that RP-deficient embryos exhibit the same normal p53 transcription, absence of p53 protein, and impaired p53 response to DNA damage as RP haploinsufficient tumor cells. Recently we reported that RP mutations suppress activity of the AKT pathway, and we show here that this suppression results in proteasomal degradation of p53. By re-activating the AKT pathway or by inhibiting GSK-3, a downstream modifier that normally represses AKT signaling, we are able to restore the stabilization of p53. Our work indicates that the anemia phenotype of zebrafish models of DBA is dependent on factors other than p53, and may hold clinical significance for both DBA and the increasing number of cancers revealing spontaneous mutations in RP genes. PMID:26132763

  11. p53 mutations and tetraploids under r- and K-selection.

    PubMed

    Chikatsu, Norio; Nakamura, Yukari; Sato, Hiroyuki; Fujita, Toshiro; Asano, Shigetaka; Motokura, Toru

    2002-05-02

    Cotransfection of rat embryo fibroblasts with c-myc and activated H-ras oncogenes is one experimental model of the multistep oncogenesis associated with p53 mutations and aneuploidy. Using the model, we found that selection processes, e.g., r- and K-selection, affect emergence of p53 mutants and tetraploids. Culture optimum for logarithmic growth (r-selection) selected p53 mutants as they proliferated rapidly, while in confluent culture (K-selection) tetraploids emerged regardless of the p53 status. Transfection of the mutated p53 gene with dominant negative functions eradicated untransfected cells under both r- and K-selection. However, these p53 mutants can be eradicated under K-selection by cells with normal p53 function and that had been selected under prolonged K-selection. The presence of competitors and the type of selection should determine whether or not p53 mutants and/or tetraploids predominate. These observations strengthen the importance of selection processes in case of cancer.

  12. Combining intracellular antibodies to restore function of mutated p53 in cancer.

    PubMed

    Chan, Grace; Jordaan, Gwen; Nishimura, Robert N; Weisbart, Richard H

    2016-01-01

    TP53 is a tumor suppressor gene that is mutated in 50% of cancers, and its function is tightly regulated by the E3 ligase, Mdm2. Both p53 and Mdm2 are localized in the cell nucleus, a site that is impervious to therapeutic regulation by most antibodies. We identified a cell-penetrating lupus monoclonal anti-DNA antibody, mAb 3E10, that targets the nucleus, and we engineered mAb 3E10 to function as an intranuclear transport system to deliver therapeutic antibodies into the nucleus as bispecific single chain Fv (scFv) fragments. Bispecific scFvs composed of 3E10 include PAb421 (3E10-PAb421) that binds p53 and restores the function of mutated p53, and 3G5 (3E10-3G5) that binds Mdm2 and prevents destruction of p53 by Mdm2. We documented the therapeutic efficacy of these bispecific scFvs separately in previous studies. In this study, we show that combination therapy with 3E10-PAb421 and 3E10-3G5 augments growth inhibition of cells with p53 mutations compared to the effect of either antibody alone. By contrast, no enhanced response was observed in cells with wild-type p53 or in cells homozygous null for p53.

  13. The p53 transcriptional pathway is preserved in ATMmutated and NOTCH1mutated chronic lymphocytic leukemias

    PubMed Central

    Rigolin, Gian Matteo; Agnoletto, Chiara; Voltan, Rebecca; Vozzi, Diego; Piscianz, Elisa; Segat, Ludovica; Dal Monego, Simeone; Cuneo, Antonio; Secchiero, Paola; Zauli, Giorgio

    2014-01-01

    By using next generation sequencing, we have analyzed 108 B chronic lymphocytic leukemia (B-CLL) patients. Among genes involved in the TP53 pathway, we found frequent mutations in ATM (n=18), TP53 (n=10) and NOTCH1 (n=10) genes, rare mutations of NOTCH2 (n=2) and CDKN1A/p21 (n=1) and no mutations in BAX, MDM2, TNFRSF10A and TNFRSF10B genes. The in vitro treatment of primary B-CLL cells with the activator of p53 Nutlin-3 induced the transcription of p53 target genes, without significant differences between the B-CLL without mutations and those harboring either ATM or NOTCH1 mutations. On the other hand, the subgroup of TP53mutated B-CLL exhibited a significantly lower induction of the p53 target genes in response to Nutlin-3 as compared to the other B-CLL samples. However, among the TP53mutated B-CLL, those showing mutations in the high hot spot region of the DNA binding domain [273-280 aa] maintained a significantly higher p53-dependent transcriptional activity as compared to the other TP53mutated B-CLL samples. Since the ability to elicit a p53-dependent transcriptional activity in vitro has a positive prognostic significance, our data suggest that ATMmutated, NOTCH1mutated and surprisingly, also a subset of TP53mutated B-CLL patients might benefit from therapeutic combinations including small molecule activator of the p53 pathway. PMID:25587027

  14. Depression of p53-independent Akt survival signals in human oral cancer cells bearing mutated p53 gene after exposure to high-LET radiation

    SciTech Connect

    Nakagawa, Yosuke; Takahashi, Akihisa; Kajihara, Atsuhisa; Yamakawa, Nobuhiro; Imai, Yuichiro; Ota, Ichiro; Okamoto, Noritomo; Mori, Eiichiro; Noda, Taichi; Furusawa, Yoshiya; Kirita, Tadaaki; Ohnishi, Takeo

    2012-07-13

    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 suggested 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 mp

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

    SciTech Connect

    Isoe, Yasuko; Okuyama, Teruhiro; Taniguchi, Yoshihito; Kubo, Takeo; Takeuchi, Hideaki

    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 zones 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.

  16. Functional interactions between p53 and the TFIIH complex are affected by tumour-associated mutations.

    PubMed Central

    Léveillard, T; Andera, L; Bissonnette, N; Schaeffer, L; Bracco, L; Egly, J M; Wasylyk, B

    1996-01-01

    The p53 tumour suppressor is mutated in the majority of human tumours. p53's proposed role as the guardian of the genome is reflected in its multiple effects on transcription genome stability, cell growth and survival. We show that p53 interacts both physically and functionally with the TFIIH complex. There are multiple protein-protein contacts, involving two regions of p53 and three subunits of TFIIH, ERCC2 (XPD), ERCC3 (XPB) and p62. p53 and its C-terminus (amino acids 320-393) inhibit both of the TFIIH helicases and in vitro transcription in the absence of TFIIH. Transcription inhibition is overcome by TFIIH. The N-terminal region of p53 (1-320), lacking the C-terminus, is inactive on its own, yet apparently affects the activity of the C-terminus in the native protein. Interestingly, mutant p53s that are frequently found in tumours are less efficient inhibitors of the helicases and transcription. We hypothesize that the interactions provide an immediate and direct link for p53 to the multiple functions of TFIIH in transcription, DNA repair and possibly the cell cycle. Images PMID:8612585

  17. VHL missense mutations in the p53 binding domain show different effects on p53 signaling and HIFα degradation in clear cell renal cell carcinoma

    PubMed Central

    Razafinjatovo, Caroline Fanja; Stiehl, Daniel; Deininger, Eva; Rechsteiner, Markus; Moch, Holger; Schraml, Peter

    2017-01-01

    Clear cell Renal Cell Carcinoma (ccRCC) formation is connected to functional loss of the von Hippel-Lindau (VHL) gene. Recent data identified its gene product, pVHL, as a multifunctional adaptor protein which interacts with HIFα subunits but also with the tumor suppressor p53. p53 is hardly expressed and rarely mutated in most ccRCC. We showed that low and absent p53 expression correlated with the severity of VHL mutations in 262 analyzed ccRCC tissues. In contrast to nonsense and frameshift mutations which abrogate virtually all pVHL functions, missense mutations may rather influence one or few functions. Therefore, we focused on four VHL missense mutations, which affect the overlapping pVHL binding sites of p53 and Elongin C, by investigating their impact on HIFα degradation, p53 expression and signaling, as well as on cellular behavior using ccRCC cell lines and tissues. TP53 mRNA and its effector targets p21, Bax and Noxa, were altered both in engineered cell lines and in tumor tissues which carried the same missense mutations. Two of these mutations were not able to degrade HIFα whereas the remaining two mutations led to HIFα downregulation, suggesting the latter are p53 binding site-specific. The selected VHL missense mutations further enhanced tumor cell survival, but had no effects on cell proliferation. Whereas Sunitinib was able to efficiently reduce cell proliferation, Camptothecin was additionally able to increase apoptotic activity of the tumor cells. It is concluded that systematic characterization of the VHL mutation status may help optimizing targeted therapy for patients with metastatic ccRCC. PMID:28052007

  18. VHL missense mutations in the p53 binding domain show different effects on p53 signaling and HIFα degradation in clear cell renal cell carcinoma.

    PubMed

    Razafinjatovo, Caroline Fanja; Stiehl, Daniel; Deininger, Eva; Rechsteiner, Markus; Moch, Holger; Schraml, Peter

    2017-02-07

    Clear cell Renal Cell Carcinoma (ccRCC) formation is connected to functional loss of the von Hippel-Lindau (VHL) gene. Recent data identified its gene product, pVHL, as a multifunctional adaptor protein which interacts with HIFα subunits but also with the tumor suppressor p53. p53 is hardly expressed and rarely mutated in most ccRCC. We showed that low and absent p53 expression correlated with the severity of VHL mutations in 262 analyzed ccRCC tissues. In contrast to nonsense and frameshift mutations which abrogate virtually all pVHL functions, missense mutations may rather influence one or few functions. Therefore, we focused on four VHL missense mutations, which affect the overlapping pVHL binding sites of p53 and Elongin C, by investigating their impact on HIFα degradation, p53 expression and signaling, as well as on cellular behavior using ccRCC cell lines and tissues. TP53 mRNA and its effector targets p21, Bax and Noxa, were altered both in engineered cell lines and in tumor tissues which carried the same missense mutations. Two of these mutations were not able to degrade HIFα whereas the remaining two mutations led to HIFα downregulation, suggesting the latter are p53 binding site-specific. The selected VHL missense mutations further enhanced tumor cell survival, but had no effects on cell proliferation. Whereas Sunitinib was able to efficiently reduce cell proliferation, Camptothecin was additionally able to increase apoptotic activity of the tumor cells. It is concluded that systematic characterization of the VHL mutation status may help optimizing targeted therapy for patients with metastatic ccRCC.

  19. P53 mutations in colorectal cancer - molecular pathogenesis and pharmacological reactivation.

    PubMed

    Li, Xiao-Lan; Zhou, Jianbiao; Chen, Zhi-Rong; Chng, Wee-Joo

    2015-01-07

    Colorectal cancer (CRC) is one of the most common malignancies with high prevalence and low 5-year survival. CRC is a heterogeneous disease with a complex, genetic and biochemical background. It is now generally accepted that a few important intracellular signaling pathways, including Wnt/β-catenin signaling, Ras signaling, and p53 signaling are frequently dysregulated in CRC. Patients with mutant p53 gene are often resistant to current therapies, conferring poor prognosis. Tumor suppressor p53 protein is a transcription factor inducing cell cycle arrest, senescence, and apoptosis under cellular stress. Emerging evidence from laboratories and clinical trials shows that some small molecule inhibitors exert anti-cancer effect via reactivation and restoration of p53 function. In this review, we summarize the p53 function and characterize its mutations in CRC. The involvement of p53 mutations in pathogenesis of CRC and their clinical impacts will be highlighted. Moreover, we also describe the current achievements of using p53 modulators to reactivate this pathway in CRC, which may have great potential as novel anti-cancer therapy.

  20. Loss of p53 in esophageal squamous cell carcinoma and the correlation with survival: analyses of gene mutations, protein expression, and loss of heterozygosity in Japanese patients.

    PubMed

    Egashira, Akinori; Morita, Masaru; Yoshida, Rintaro; Saeki, Hiroshi; Oki, Eiji; Sadanaga, Noriaki; Kakeji, Yoshihiro; Tsujitani, Shun-Ichi; Maehara, Yoshihiko

    2011-08-01

    A high frequency of p53 protein expression or gene mutation has been reported in the early stages of esophageal squamous cell carcinoma (ESCC), and thus loss of p53 function is thought to be very important in esophageal carcinogenesis. However, there is controversy surrounding the correlation between p53 dysfunction and ESCC tumor progression. The complexity arises from the different modalities, such as mutation analysis, immunohistochemistry, and the detection of loss of heterozygosity (LOH) at the p53 genomic locus. In this study, we comprehensively analyzed p53 gene mutation, p53 protein expression, and LOH at 17p13 in 94 surgically resected Japanese cases of ESCC. The frequency of p53 gene mutation was 60.6%. The rate of positive p53 protein expression was 56.4%. The frequency of LOH at 17p13 was 67.5%. There was a statistically significant correlation between the presence of a gene mutation and LOH, whereas, there was no significant correlation between gene mutation and protein expression. Despite the importance of loss of p53 function in esophageal carcinogenesis, none of the examined parameters, either singly or combined, correlated with overall survival. Taken together, p53 function is a primary target for esophageal carcinogenesis but there is no apparent correlation with the malignant phenotype in ESCC. Copyright © 2011 Wiley-Liss, Inc.

  1. Frequent mutation of the p53 gene in human esophageal cancer

    SciTech Connect

    Hollstein, M.C.; Montesano, R. ); Metcalf, R.A.; Welsh, J.A.; Harris, C.C. )

    1990-12-01

    Sequence alterations in the p53 gene have been detected in human tumors of the brain, breast, lung, and colon, and it has been proposed that p53 mutations spanning a major portion of the coding region inactivate the tumor suppressor function of this gene. To our knowledge, neither transforming mutations in oncogenes nor mutations in tumor suppressor genes have been reported in human esophageal tumors. The authors examined four human esophageal carcinoma cell lines and 14 human esophageal squamous cell carcinomas by polymerase chain reaction amplification and direct sequencing for the presence of p53 mutations in exons 5,6,7,8, and 9. Two cell lines and five of the tumor speicmens contained a mutated allele (one frameshift and six missense mutations). All missense mutations detected occurred at G{center dot}C base pairs in codons at or adjacent to mutations previously reported in other cancers. The identification of aberrant p53 genes alleles in one-third of the tumors they tested suggests that mutations at this locus are common genetic events in the pathogenesis of squamous cell carcinomas of the esophagus.

  2. p53 mutation is a poor prognostic indicator for survival in patients with hepatocellular carcinoma undergoing surgical tumour ablation.

    PubMed Central

    Honda, K.; Sbisà, E.; Tullo, A.; Papeo, P. A.; Saccone, C.; Poole, S.; Pignatelli, M.; Mitry, R. R.; Ding, S.; Isla, A.; Davies, A.; Habib, N. A.

    1998-01-01

    Forty-two patients with hepatocellular carcinoma (HCC) were resected and their tumours were analysed for p53 mutations by GC-clamped denaturing gradient gel electrophoresis (DGGE), single-strand conformation polymorphism (SSCP) and gene sequencing. All the exons have been analysed in this study. Eight of 12 HCCs with cirrhosis due to viral hepatitis and the two patients with sarcomatoid changes displayed p53 mutations. In contrast, no mutation was observed in the fibrolamellar variant (n = 9), non-cirrhotics (n = 13) and alcoholic cirrhosis (n = 6). The mutations observed were in exons 5-8. Two mutations were observed in codons 136 and 213 as well as a T insertion between residues 156 and 157 (exon 5) and these are reported for the first time in HCC. Likewise, the silent mutation polymorphism in codon 213 was noticed in 3 of the 42 patients. Survival analysis of these patients after surgery showed the mean and median survival in patients with wild-type p53 to be 60 and 43 months respectively. In the group with p53 mutations, the mean and median survival was 15 and 12 months. The difference was statistically significant (P= 0.003). Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:9514057

  3. High prevalence of mutations of the p53 gene in poorly differentiated human thyroid carcinomas.

    PubMed Central

    Fagin, J A; Matsuo, K; Karmakar, A; Chen, D L; Tang, S H; Koeffler, H P

    1993-01-01

    The development and progression of thyroid tumors is signaled by phenotype-specific mutations of genes involved in growth control. Molecular events associated with undifferentiated thyroid cancer are not known. We examined normal, benign, and malignant thyroid tissue for structural abnormalities of the p53 tumor suppressor gene. Mutations were detected by single-strand conformation polymorphisms of PCR-amplified DNA, using primers bracketing the known hot spots on either exons 5, 6, 7, or 8. The prevalence of mutations was as follows: normal thyroid 0/6; follicular adenomas 0/31; papillary carcinomas 0/37; medullary carcinomas 0/2; follicular carcinomas 1/11; anaplastic carcinomas 5/6; thyroid carcinoma cell lines 3/4. Positive cases were confirmed by direct sequencing of the PCR products. All five anaplastic carcinoma tissues and the anaplastic carcinoma cell line ARO had G:C to A:T transitions leading to an Arg to His substitution at codon 273. In both tumors and cell lines, examples of heterozygous and homozygous p53 mutations were identified. The only thyroid carcinoma cell line in which p53 mutations were not detected in exons 5-8 had markedly decreased p53 mRNA levels, suggesting the presence of a structural abnormality of either p53 itself or of some factor controlling its expression. The presence of p53 mutations almost exclusively in poorly differentiated thyroid tumors and thyroid cancer cell lines suggests that inactivation of p53 may confer these neoplasms with aggressive properties, and further loss of differentiated function. Images PMID:8423216

  4. Evidence for activation of mutated p53 by apigenin in human pancreatic cancer

    PubMed Central

    King, Jonathan C; Lu, Qing-Yi; Li, Gang; Moro, Aune; Takahashi, Hiroki; Chen, Monica; Go, Vay Liang W; Reber, Howard A; Eibl, Guido; Hines, O. Joe

    2012-01-01

    Pancreatic cancer is an exceedingly lethal disease with a five-year survival that ranks among the lowest of gastrointestinal malignancies. Part of its lethality is attributable to a generally poor response to existing chemotherapeutic regimens. New therapeutic approaches are urgently needed. We aimed to elucidate the anti-neoplastic mechanisms of apigenin-an abundant, naturally-occurring plant flavonoid-with a particular focus on p53 function. Pancreatic cancer cells (BxPC-3, MiaPaCa-2) experienced dose and time-dependent growth inhibition and increased apoptosis with apigenin treatment. p53 post-translational modification, nuclear translocation, DNA binding, and upregulation of p21 and PUMA were all enhanced by apigenin treatment despite mutated p53 in both cell lines. Transcription-dependent p53 activity was reversed by pifithrin-α, a specific DNA binding inhibitor of p53, but not growth inhibition or apoptosis suggesting transcription-independent p53 activity. This was supported by immunoprecipitation assays which demonstrated disassociation of p53/BclXL and PUMA/BclXL and formation of complexes with Bak followed by Cytochrome c release. Treated animals grew smaller tumors with increased cellular apoptosis than those fed control diet. These results suggest that despite deactivating mutation, p53 retains some of its function which is augmented following treatment with apigenin. Cell cycle arrest and apoptosis induction may be mediated by transcription-independent p53 function via interactions with BclXL and PUMA. Further study of flavonoids as chemotherapeutics is warranted PMID:22227579

  5. Human papillomavirus and p53 mutations in head and neck squamous cell carcinoma among Japanese population.

    PubMed

    Maruyama, Hiromi; Yasui, Toshimichi; Ishikawa-Fujiwara, Tomoko; Morii, Eiichi; Yamamoto, Yoshifumi; Yoshii, Tadashi; Takenaka, Yukinori; Nakahara, Susumu; Todo, Takeshi; Hongyo, Tadashi; Inohara, Hidenori

    2014-04-01

    We aimed to reveal the prevalence and pattern of human papillomavirus (HPV) infection and p53 mutations among Japanese head and neck squamous cell carcinoma (HNSCC) patients in relation to clinicopathological parameters. Human papillomavirus DNA and p53 mutations were examined in 493 HNSCCs and its subset of 283 HNSCCs. Oropharyngeal carcinoma was more frequently HPV-positive than non-oropharyngeal carcinoma (34.4% vs 3.6%, P < 0.001), and HPV16 accounted for 91.1% of HPV-positive tumors. In oropharyngeal carcinoma, which showed an increasing trend of HPV prevalence over time (P < 0.001), HPV infection was inversely correlated with tobacco smoking, alcohol drinking, p53 mutations, and a disruptive mutation (P = 0.003, <0.001, <0.001, and <0.001, respectively). The prevalence of p53 mutations differed significantly between virus-unrelated HNSCC and virus-related HNSCC consisting of nasopharyngeal and HPV-positive oropharyngeal carcinomas (48.3% vs 7.1%, P < 0.001). Although p53 mutations were associated with tobacco smoking and alcohol drinking, this association disappeared in virus-unrelated HNSCC. A disruptive mutation was never found in virus-related HNSCC, whereas it was independently associated with primary site, such as the oropharynx and hypopharynx (P = 0.01 and 0.03, respectively), in virus-unrelated HNSCC. Moreover, in virus-unrelated HNSCC, G:C to T:A transversions were more frequent in ever-smokers than in never-smokers (P = 0.04), whereas G:C to A:T transitions at CpG sites were less frequent in ever-smokers than in never-smokers (P = 0.04). In conclusion, HNSCC is etiologically classified into virus-related and virus-unrelated subgroups. In virus-related HNSCC, p53 mutations are uncommon with the absence of a disruptive mutation, whereas in virus-unrelated HNSCC, p53 mutations are common, and disruptive mutagenesis of p53 is related with oropharyngeal and hypopharyngeal carcinoma.

  6. Different mutation profiles associated to P53 accumulation in colorectal cancer.

    PubMed

    López, Ignacio; P Oliveira, Ligia; Tucci, Paula; Alvarez-Valín, Fernando; A Coudry, Renata; Marín, Mónica

    2012-05-10

    The tumor suppressor TP53 gene is one of the most frequently mutated in different types of human cancer. Particularly in colorectal cancer (CRC), it is believed that TP53 mutations play a role in the adenoma-carcinoma transition of tumors during pathological process. In order to analyze TP53 expressed alleles in CRC, we examined TP53 mRNA in tumor samples from 101 patients with sporadic CRC. Samples were divided in two groups defined according to whether they exhibit positive or negative P53 protein expression as detected by immunohistochemistry (IHC). The presence of TP53 mutation was a common event in tumors with an overall frequency of 54.5%. By direct sequencing, we report 42 different TP53 sequence changes in 55 CRC patients, being two of them validated polymorphisms. TP53 mutations were more frequent in positive than in negative P53 detection group (p<0.0001), being the precise figures 79.6% and 30.8%, respectively. In addition, the mutation profiles were also different between the two groups of samples; while most of the mutations detected in P53 positive group were missense (38 out of 39), changes in P53 negative detection group include 7 insertions/deletions, 6 missense, 2 nonsense and 1 silent mutation. As previously observed, most mutations were concentrated in regions encoding P53 DNA binding domain (DBD). Codons 175, 248 and 273 together account for 36.7% of point mutations, in agreement with previous observations provided that these codons are considered mutation hotspots. Interestingly, we detected two new deletions and two new insertions. In addition, in three samples we detected two deletions and one insertion that could be explained as putative splicing variants or splicing errors.

  7. Functional studies of a novel germline p53 splicing mutation identified in a patient with Li-Fraumeni-like syndrome.

    PubMed

    Piao, Jinhua; Sakurai, Naoto; Iwamoto, Shotaro; Nishioka, Junji; Nakatani, Kaname; Komada, Yoshihiro; Mizutani, Shuki; Takagi, Masatoshi

    2013-10-01

    Most p53 mutations identified in Li-Fraumeni syndrome (LFS) are missense mutations; splicing mutations have rarely been reported. A novel splicing p53 mutation was identified in a patient with Li-Fraumeni-like syndrome (LFL). Usually, p53 missense mutants identified in LFS and cancer cells function as dominant negative mutations interfering with wild-type p53 function. However, the mechanism by which p53 haploinsufficiency causes carcinogenesis is not well characterized. In this study, we describe a novel splicing mutation that results in the loss-of-function of p53. These findings suggest a linkage between the loss-of-function type p53 mutation and a LFL phenotype.

  8. Gastrointestinal stromal tumors: clinical significance of p53 expression, MDM2 amplification, and KIT mutation status.

    PubMed

    Wallander, Michelle L; Layfield, Lester J; Tripp, Sheryl R; Schmidt, Robert L

    2013-07-01

    Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. Clinical behavior is best predicted by size and mitotic count (risk index). KIT and platelet-derived growth factor receptor α (PDGFRA) mutations have therapeutic and prognostic value but few other prognostically significant molecular markers have been identified. We investigated the prognostic value of p53 protein expression and MDM2 gene amplification in a series of GISTs. Thirty-five GISTs were tested for KIT and PDGFRA mutations, p53 protein expression (high >10% positive by immunohistochemistry) and MDM2 gene amplification (ratio >1.8). Mitotic index (>5/50 HPF), MDM2 amplification status, p53 protein expression, tumor size, and KIT/PDGFRA mutational status were correlated with clinical outcome. Only a single (3%) GIST was amplified for MDM2. p53 protein expression, mitotic index, and KIT/PDGFRA mutations did not correlate with recurrence or metastasis (P=0.20, 0.50, and 0.08, respectively) but tumor size did (P=0.04). Risk assessment (size and mitotic index) showed a weak association with clinical behavior (P=0.19). MDM2 amplification is uncommon in GISTs. Although high p53 expression occurred in 35% of cases, it did not correlate with clinical behavior. Only GIST size predicted clinical outcome.

  9. p53 gene mutational rate, Gleason score, and BK virus infection in prostate adenocarcinoma: Is there a correlation?

    PubMed

    Russo, Giuseppe; Anzivino, Elena; Fioriti, Daniela; Mischitelli, Monica; Bellizzi, Anna; Giordano, Antonio; Autran-Gomez, Anamaria; Di Monaco, Franco; Di Silverio, Franco; Sale, Patrizio; Di Prospero, Laura; Pietropaolo, Valeria

    2008-12-01

    Prostate cancer represents the second leading cause of cancer deaths in Western countries. Viral infections could play a role in prostate carcinogenesis. Human polyomavirus BK (BKV) is a possible candidate because of its transforming properties. In this study, BKV sequences in urine, blood, fresh, and paraffin-embedded prostate cancer samples from 26 patients were searched using Q-PCR analysis. T antigen (TAg) and p53 localization in neoplastic cells were evaluated by immunohistochemical analysis. Also, the presence of mutations in 5-9 exons of p53 gene was analyzed. Results showed that BKV-DNA was found in urine (54%), plasma (31%), and in fresh prostate cancer specimens (85%). The analysis of p53 gene evidenced several mutations in high Gleason patients, according to tumor advanced stage. Immunohistochemical analysis results evidenced the localization of p53 and TAg into cytoplasm, whereas in TAg-negative tumors, p53 was nuclear. This study suggests that BKV acts as cofactor in the pathogenesis of prostate cancer. These observations emphasize previous studies regarding the cellular pathways that may be deregulated by BKV.

  10. p53 protein expression and gene mutation in phyllodes tumors of the breast.

    PubMed

    Gatalica, Z; Finkelstein, S; Lucio, E; Tawfik, O; Palazzo, J; Hightower, B; Eyzaguirre, E

    2001-01-01

    The malignant potential of mammary phyllodes tumors is difficult to assess on initial pathologic examination. Studies on the p53 tumor suppressor gene have shown that it has an important role in the development of a variety of malignancies, yet the specific contribution to the pathogenesis and development of the malignant potential of phyllodes tumor is largely unknown. We studied p53 protein expression in 25 cases of phyllodes tumors histologically classified as either malignant (12 cases) or benign (13 cases). Using microdissection approach, we also analyzed the p53 gene sequence in a case that demonstrated progression from benign to malignant phenotype. Nuclear p53 staining was detected in various proportions (1-90%) of neoplastic stromal cells of malignant tumors. No staining was found in benign tumors. Progression from benign to malignant phenotype was associated with a significant increase in the accumulation of p53 (more than 20 times). This was caused by an underlying missense mutation in exon 7, resulting in a change from Arg248 to Trp248 in the malignant component of the tumor. Stromal p53 over-expression was observed only in neoplasms histologically classified as malignant and was associated with an increased proliferation index (MIB-1 staining). These two markers may be used as useful adjuncts in the diagnosis of malignancy in difficult cases or when only a limited sample size is available. Somatic mutation in exon 7 of p53 gene in malignant phyllodes tumor points toward the importance of p53 in the malignant transformation of phyllodes tumors.

  11. Preferential Formation of Benzo[a]pyrene Adducts at Lung Cancer Mutational Hotspots in P53

    NASA Astrophysics Data System (ADS)

    Denissenko, Mikhail F.; Pao, Annie; Tang, Moon-Shong; Pfeifer, Gerd P.

    1996-10-01

    Cigarette smoke carcinogens such as benzo[a]pyrene are implicated in the development of lung cancer. The distribution of benzo[a]pyrene diol epoxide (BPDE) adducts along exons of the P53 gene in BPDE-treated HeLa cells and bronchial epithelial cells was mapped at nucleotide resolution. Strong and selective adduct formation occurred at guanine positions in codons 157, 248, and 273. These same positions are the major mutational hotspots in human lung cancers. Thus, targeted adduct formation rather than phenotypic selection appears to shape the P53 mutational spectrum in lung cancer. These results provide a direct etiological link between a defined chemical carcinogen and human cancer.

  12. Loss of heterozygosity and mutation analysis of the p16 (9p21) and p53 (17p13) genes in squamous cell carcinoma of the head and neck.

    PubMed

    González, M V; Pello, M F; López-Larrea, C; Suárez, C; Menéndez, M J; Coto, E

    1995-09-01

    We analyzed allelic loss at the p53 gene (17p13) and at chromosome region 9p21 in 35 primary head and neck squamous cell carcinomas. Loss of heterozygosity (LOH) at p53 and 9p21 was found in 50 and 75% of informative cases, respectively. LOH at the p53 gene did not increase significantly with tumor stage, but was more frequent in moderately and poorly differentiated tumors than in well-differentiated tumors. LOH plus mutation or homozygous deletion of p53 was limited to advanced stage and poorly differentiated tumors. Allelic loss at 9p21 is frequent in early stage head and neck squamous cell carcinoma and is not significantly associated with LOH at p53. The second exon of the p16/MTS1/CDKN2 gene was found to be homozygously deleted in 1 of 19 cases showing LOH at 9p21, but direct sequencing did not show mutations in the remaining 18 cases. This suggests that p16 plays a limited role in the development of head and neck squamous cell carcinoma.

  13. P53 germline mutations in childhood cancers and cancer risk for carrier individuals

    PubMed Central

    Chompret, A; Brugières, L; Ronsin, M; Gardes, M; Dessarps-Freichey, F; Abel, A; Hua, D; Ligot, L; Dondon, M-G; Paillerets, B Bressac-de; Frébourg, T; Lemerle, J; Bonaïti-Pellié, C; Feunteun, J

    2000-01-01

    The family history of cancer in children treated for a solid malignant tumour in the Paediatric Oncology Department at Institute Gustave-Roussy, has been investigated. In order to determine the role of germline p53 mutations in genetic predisposition to childhood cancer, germline p53 mutations were sought in individuals with at least one relative (first- or second-degree relative or first cousin) affected by any cancer before 46 years of age, or affected by multiple cancers. Screening for germline p53 mutation was possible in 268 index cases among individuals fulfilling selection criteria. Seventeen (6.3%) mutations were identified, of which 13 were inherited and four were de novo. Using maximum likelihood methods that incorporate retrospective family data and correct for ascertainment bias, the lifetime risk of cancer for mutation carriers was estimated to be 73% for males and nearly 100% for females with a high risk of breast cancer accounting for the difference. The risk of cancer associated with such mutations is very high and no evidence of low penetrance mutation was found. These mutations are frequently inherited but de novo mutations are not rare. © 2000 Cancer Research Campaign PMID:10864200

  14. Identification of a germ-line mutation in the p53 gene in a patient with an intracranial ependymoma

    SciTech Connect

    Metzger, A.K.; Duyk, G.; Daneshvar, L.; Edwards, M.S.B.; Cogen, P.H. ); Sheffield, V.C. )

    1991-09-01

    The authors detected a germ-line mutation of the p53 gene in a patient with a malignant ependymoma of the posterior fossa. This mutation, which was found at codon 242, resulted in an amino acid substitution in a highly conserved site of exon 7 of the p53 gene; the same mutation was found in both the germ-line and tumor tissue. This is the most common region of previously described somatic p53 mutations in tumor specimens and of the germ-line p53 mutations in patients with the Li-Fraumeni cancer syndrome. Evaluation of the patient's family revealed several direct maternal and paternal relatives who had died at a young age from different types of cancer. The association of a germ-line p53 mutation with an intracranial malignancy and a strong family history of cancer suggests that p53 gene mutations predispose a person to malignancy and, like retinoblastoma mutations, may be inherited.

  15. Mutations of the p53 and PTCH gene in basal cell carcinomas: UV mutation signature and strand bias.

    PubMed

    Kim, Mi-Yeon; Park, Hyun Jeong; Baek, Seung-Cheol; Byun, Dae Gyoo; Houh, Dong

    2002-05-01

    Mutations of p53 and PTCH gene, two candidate tumor suppressor genes for basal cell carcinoma (BCC), were screened in 15 cases of sporadic BCCs that developed in sun-exposed skin region in a Korean population. p53 and PTCH mutations were detected at a frequency of 33 and 40%, respectively, and the mutations were predominantly UV-signature transition, C-->T transitions at dipyrimidine sites and CC-->TT tandem mutations. In both genes, the most common mutations were missense mutations resulting in amino acid substitution, which is different than the results from Caucasian BCCs where mutations are frequently predicted to make truncated or absent proteins. All mutations, except for one, occurred on the nontranscribed strand where is little efficient removal of UV-induced pyrimidine dimers relative to the transcribed strand. Loss of heterozygocity (LOH) of 9q22 for PTCH loci was found in eight of 15 informative cases of BCCs (53%), but none of the cases were informative for LOH of 17p13 for p53 loci. Not only do our data indicate the key role played by p53 and PTCH in the development of BCCs, these findings also suggest that UVB may significantly contribute to BCC tumorigenesis. Moreover, molecular epidemiology composed of incidence of p53 and PTCH mutations, difference in the type of mutation and repair bias of UV-induced DNA lesions might affect the distinct features of BCCs between different racial population.

  16. Altered-function p53 missense mutations identified in breast cancers can have subtle effects on transactivation

    PubMed Central

    Jordan, Jennifer J.; Inga, Alberto; Conway, Kathleen; Edmiston, Sharon; Carey, Lisa A.; Wu, Lin; Resnick, Michael A.

    2010-01-01

    Mutations of the sequence-specific master regulator p53 that alter transactivation function from promoter response elements (REs) could result in changes in the strength of gene activation or spectra of genes regulated. Such mutations in this tumor suppressor might lead to dramatic phenotypic changes and diversification of cell responses to stress. We have determined “functional fingerprints” of sporadic breast cancer-related p53 mutants many of which are also associated with familial cancer proneness such as the Li-Fraumeni Syndrome and germline BRCA1/2 mutant-associated cancers. The ability of p53, wild type and mutants, to transactivate from 11 human target REs has been assessed at variable expression levels using a cellular, isogenomic yeast model system that allows for the rapid analysis of p53 function using a qualitative and a quantitative reporter. Among 50 missense mutants, 29 were classified as loss-of-function. The remaining 21 retained transactivation towards at least one RE. At high levels of galactose induced p53 expression, 12/21 mutants that retain transactivation appeared similar to WT. When the level of galactose was reduced, transactivation defects could be revealed suggesting that some breast cancer related mutants can have subtle changes in transcription. These findings have been compared with clinical data from an ongoing neoadjuvant chemotherapy treatment trial for locally advanced breast tumors. The functional and nonfunctional missense mutations may distinguish tumors in terms of demographics, appearance and relapse, implying that heterogeneity in the functionality of specific p53 mutations could impact clinical behavior and outcome. PMID:20407015

  17. Altered-function p53 missense mutations identified in breast cancers can have subtle effects on transactivation.

    PubMed

    Jordan, Jennifer J; Inga, Alberto; Conway, Kathleen; Edmiston, Sharon; Carey, Lisa A; Wu, Lin; Resnick, Michael A

    2010-05-01

    Mutations of the sequence-specific master regulator p53 that alter transactivation function from promoter response elements (RE) could result in changes in the strength of gene activation or spectra of genes regulated. Such mutations in this tumor suppressor might lead to dramatic phenotypic changes and diversification of cell responses to stress. We have determined "functional fingerprints" of sporadic breast cancer-related p53 mutants, many of which are also associated with familial cancer proneness such as the Li-Fraumeni syndrome and germline BRCA1/2 mutant-associated cancers. The ability of p53, wild-type and mutants, to transactivate from 11 human target REs has been assessed at variable expression levels using a cellular, isogenomic yeast model system that allows for the rapid analysis of p53 function using a qualitative and a quantitative reporter. Among 50 missense mutants, 29 were classified as loss of function. The remaining 21 retained transactivation toward at least one RE. At high levels of galactose-induced p53 expression, 12 of 21 mutants that retain transactivation seemed similar to wild-type. When the level of galactose was reduced, transactivation defects could be revealed, suggesting that some breast cancer-related mutants can have subtle changes in transcription. These findings have been compared with clinical data from an ongoing neoadjuvant chemotherapy treatment trial for locally advanced breast tumors. The functional and nonfunctional missense mutations may distinguish tumors in terms of demographics, appearance, and relapse, implying that heterogeneity in the functionality of specific p53 mutations could affect clinical behavior and outcome.

  18. Quantitative analysis of γ-H2AX and p53 nuclear expression levels in ovarian and fallopian tube epithelium from risk-reducing salpingo-oophorectomies in BRCA1 and BRCA2 mutation carriers.

    PubMed

    Staff, Synnöve; Tolonen, Teemu; Laasanen, Satu-Leena; Mecklin, Jukka-Pekka; Isola, Jorma; Mäenpää, Johanna

    2014-05-01

    Mutations in BRCA1 and BRCA2 genes confer an increased lifetime risk for breast and ovarian cancer. Increased lifetime ovarian cancer risk among BRCA1/BRCA2 mutation carriers can be substantially decreased by risk-reducing salpingo-oophorectomy (RRSO), which also provides material for molecular research on early pathogenesis of serous ovarian cancer. RRSO studies have suggested fallopian tube as a primary site of serous high-grade ovarian cancer. In this study, the nuclear expression levels of γ-H2AX and p53 using immunohistochemical (IHC) study was quantitatively assessed in ovarian and fallopian tube epithelium derived from RRSOs in 29 BRCA1 and BRCA2 mutation carriers and in 1 patient with a strong family history of breast and ovarian cancer but showing an unknown BRCA status. Both p53 and γ-H2AX nuclear staining levels were significantly higher in BRCA1/2 mutation-positive fallopian tube epithelium compared with the control fallopian tube epithelium (P<0.006 and P=0.011, respectively). Nuclear expression levels of p53 and γ-H2AX were similar between the BRCA1/2 mutation-positive ovarian epithelium and controls. Both γ-H2AX and p53 showed significantly higher nuclear expression levels in BRCA1/2 mutation-positive fallopian tube epithelium compared with BRCA1/2 mutation-positive ovarian epithelium (P<0.0001 and P<0.0001, respectively). BRCA1/2 mutation-positive fallopian tube epithelium showed a positive correlation between the γ-H2AX and p53 nuclear expression levels (Pearson r=0.508, P=0.003). Our results of quantitative nuclear p53 and γ-H2AX expression levels in ovarian and fallopian tube epithelium derived from RRSO in high-risk patients support the previously suggested role of fallopian tube epithelium serving as a possible site of initial serous ovarian carcinogenesis.

  19. ZIKA virus elicits P53 activation and genotoxic stress in human neural progenitors similar to mutations involved in severe forms of genetic microcephaly and p53

    PubMed Central

    Ghouzzi, Vincent El; Bianchi, Federico T; Molineris, Ivan; Mounce, Bryan C; Berto, Gaia E; Rak, Malgorzata; Lebon, Sophie; Aubry, Laetitia; Tocco, Chiara; Gai, Marta; Chiotto, Alessandra MA; Sgrò, Francesco; Pallavicini, Gianmarco; Simon-Loriere, Etienne; Passemard, Sandrine; Vignuzzi, Marco; Gressens, Pierre; Di Cunto, Ferdinando

    2016-01-01

    Epidemiological evidence from the current outbreak of Zika virus (ZIKV) and recent studies in animal models indicate a strong causal link between ZIKV and microcephaly. ZIKV infection induces cell-cycle arrest and apoptosis in proliferating neural progenitors. However, the mechanisms leading to these phenotypes are still largely obscure. In this report, we explored the possible similarities between transcriptional responses induced by ZIKV in human neural progenitors and those elicited by three different genetic mutations leading to severe forms of microcephaly in mice. We found that the strongest similarity between all these conditions is the activation of common P53 downstream genes. In agreement with these observations, we report that ZIKV infection increases total P53 levels and nuclear accumulation, as well as P53 Ser15 phosphorylation, correlated with genotoxic stress and apoptosis induction. Interestingly, increased P53 activation and apoptosis are induced not only in cells expressing high levels of viral antigens but also in cells showing low or undetectable levels of the same proteins. These results indicate that P53 activation is an early and specific event in ZIKV-infected cells, which could result from cell-autonomous and/or non-cell-autonomous mechanisms. Moreover, we highlight a small group of P53 effector proteins that could act as critical mediators, not only in ZIKV-induced microcephaly but also in many genetic microcephaly syndromes. PMID:27787521

  20. p53 mutations associated with increased sensitivity to ionizing radiation in human head and neck cancer cell lines.

    PubMed

    Servomaa, K; Kiuru, A; Grénman, R; Pekkola-Heino, K; Pulkkinen, J O; Rytömaa, T

    1996-05-01

    The p53 tumour suppressor gene is activated following cellular exposure to DNA-damaging agents. The functions of wild-type p53 protein include transient blocking of cell cycle progression, direct or indirect stimulation of DNA repair machinery and triggering of apoptosis if DNA repair fails. Therefore, the status of p53 protein may be critically associated with tumour cell radiosensitivity. In the present study we examine the intrinsic radiosensitivity of 20 human carcinoma cell lines derived from 15 patients with different types of head and neck tumour. Radiosensitivities were measured in a 96-well plate clonogenic assay in terms of the mean inactivation dose, surviving fraction at 2 Gy, and constants alpha and beta in the linear quadratic survival curve. The p53 allele status was determined by amplifying exons 4-10 by the polymerase chain reaction (PCR), screening for mutations using single-strand conformation polymorphism (SSCP) analysis and determining the exact type and location of a mutation by direct sequencing. The results showed that prevalence of p53 mutations in squamous cell carcinoma (SCC) cell lines is high (80%), and that deletion of one or both wild-type alleles is common (75%). Intrinsic radiosensitivity of the cell lines varied greatly in terms of mean inactivation dose, from 1.4 +/- 0.1 to 2.6 +/- 0.2 Gy. Radiosensitivity correlated well with the p53 allele status so that cell lines carrying a wild-type p53 allele were significantly (P < 0.01) more radioresistant (mean inactivation dose 2.23 +/- 0.15 Gy) than cell lines which lacked a wild-type gene (1.82 +/- 0.24 Gy). Evaluation of our own results and those published in the literature lead us to conclude that absence of the wild-type p53 allele in human head and neck cancer cell lines is associated with increased radiosensitivity. However, the sensitivity is also strongly dependent on the exact type and location of the p53 mutation.

  1. Widely dispersed p53 mutation in respiratory epithelium. A novel mechanism for field carcinogenesis.

    PubMed Central

    Franklin, W A; Gazdar, A F; Haney, J; Wistuba, I I; La Rosa, F G; Kennedy, T; Ritchey, D M; Miller, Y E

    1997-01-01

    Individuals with one aerodigestive tract malignancy have a high incidence of second primary aerodigestive tumors. The mechanism for this field effect has not been determined. We studied an individual with widespread dysplastic changes in the respiratory epithelium but no overt carcinoma. The entire tracheobronchial tree obtained at autopsy was embedded in paraffin, and bronchial epithelial cells were isolated by microdissection. DNA extracted from the microdissected cells was analyzed for point mutations in the p53 tumor suppressor gene. A single, identical point mutation consisting of a G:C to T:A transversion in codon 245 was identified in bronchial epithelium from 7 of 10 sites in both lungs. Epithelium at sites containing the p53 mutation was morphologically abnormal, exhibiting squamous metaplasia and mild to moderate atypia. No invasive tumor was found in the tracheobronchial tree or any other location. Cells from peripheral blood, kidney, liver, and lymph node exhibited no abnormality in the p53 gene. The widespread presence of a single somatic p53 point mutation in the bronchi of a smoker suggests that a single progenitor bronchial epithelial clone may expand to populate broad areas of the bronchial mucosa-a novel mechanism for field carcinogenesis in the respiratory epithelium that may be of importance in assessing individuals for risk of a second primary tumor as well as in devising effective strategies for chemoprevention of lung cancer. PMID:9329980

  2. Canine tumour suppressor gene p53--mutation in a case of adenoma of circumanal glands.

    PubMed

    Mayr, B; Schaffner, W; Botto, I; Reifinger, M; Loupal, G

    1997-07-01

    Highly conserved regions of the tumour suppressor gene p53, including the typical human tumour hot spots (codons 175, 245, 248, 249, 273 and 282), were investigated in various canine neoplasms. A mutation CGG-->TGG (arginine-->tryptophan) was detected in codon 249 in an adenoma of the circumanal gland.

  3. Canine tumour suppressor gene p53 mutation in a case of anaplastic carcinoma of the intestine.

    PubMed

    Mayr, B; Reifinger, M

    2002-01-01

    Tumours localised in the large bowel of dogs were subjected to molecular genetic studies. Highly conserved regions of the tumour suppressor gene p53, including typical tumour hot spots (codons 175, 245, 248, 249, 273 and 282), were analysed. A mutation CGG-->TGG (arginine-->tryptophan) was present in codon 249 in an anaplastic carcinoma in the caecum.

  4. Association Between BRCA Status and P53 Status in Breast Cancer: A Meta-Analysis

    PubMed Central

    Peng, Lin; Xu, Tao; Long, Ting; Zuo, Huaiquan

    2016-01-01

    Background Research on BRCA mutation has meaningful clinical implications, such as identifying risk of second primary cancers and risk of hereditary cancers. This study seeks to summarize available data to investigate the association between BRCA status and P53 status by meta-analysis. Material/Methods We searched PubMed, Embase, and Cochrane library databases for relevant studies. Meta-analysis was conducted using STATA software. We summarized odds ratios by fixed-effects or random-effects models. Results This study included a total of 4288 cases from 16 articles, which including 681 BRCA1 mutation carriers (BRCA1Mut), 366 carriers of BRCA2 mutation (BRCA2Mut), and 3241 carriers of normal versions of these genes. BRCA1Mut was significantly associated with P53 over-expression compared with BRCA2Mut (OR 1.851, 95% CI=1.393–2.458) or non-carriers (OR=2.503, 95% CI=1.493–4.198). No difference was found between p53 protein expression in BRCA2 Mut carriers and non-carriers (OR=0.881, 95% CI=0.670–1.158). Conclusions Our meta-analysis suggests that BRCA1Mut breast cancer patients are more likely to have P53 overexpression compared with BRCA2Mut and non-carriers. This information provides valuable information for clinicians who perform related studies in the future. PMID:27272763

  5. Relation between food habits and p53 mutational spectrum in gastric cancer patients.

    PubMed

    Fedriga, R; Calistri, D; Nanni, O; Cortesi, L; Saragoni, L; Amadori, D

    2000-07-01

    p53 tumour suppressor gene mutations were analysed in gastric cancer in relation to food habits and social class in 56 patients from a high risk region of Italy. Exons 5-8 were analysed with DGGE method on amplified DNA from formalin-fixed paraffin-embedded samples. All p53 mutations were observed in patients belonging to low social class and the majority of mutations were found in intestinal type cancers. A positive association was also found with low raw vegetables, fresh, dried and preserved fruits, and ascorbic acid intake. Moreover, specific types of mutations were significantly associated with particular factors, thus suggesting the presence of specific molecular etiologic process in stomach carcinogenesis.

  6. Identification of known p53 point mutations by capillary electrophoresis using unique mobility profiles in a blinded study.

    PubMed

    Wenz, H M; Ramachandra, S; O'Connell, C D; Atha, D H

    1998-05-01

    This study is part of an ongoing project at the National Institute of Standards and Technology (NIST) that generates a panel of DNA clones containing the most common mutations found in the human p53 tumor suppressor gene. This panel will be made available as a reference source for evaluation and testing for p53 mutations. Single strand conformation polymorphism (SSCP) analysis has found widespread acceptance as a tool for simply and rapidly screening for mutations, albeit with a detection rate that can be below 100%. We have begun to analyze mutations found in exon 7 of the p53 gene by SSCP using laser induced fluorescence capillary electrophoresis (LIF-CE). PCR fragments, containing single point mutations, were amplified from genomic DNA isolated from cell lines using primers labeled with two different fluorophores. This dual labeling approach allowed better traceability of mobility shifts as a function of the experimental conditions. While analyzing the clones H596, Colo320, Namalwa and wild type (reference samples) at different temperatures, ranging from 25 to 45 degrees C, it was observed that each mutation responded in a unique way to changes in temperature both in magnitude and direction of shifts relative to the wild type sample. In a blinded study, ten p53 exon 7 samples were matched automatically, using ABI PRISM Genotyper software, against the four reference samples. From these 10 samples, six were correctly identified as containing one of the reference mutations, two corresponded to wild type, and two were correctly identified as non-reference mutations. This approach should prove helpful in the rapid screening of target sequences that are known to bear a limited number of mutations.

  7. Comparison of Effects of p53 Null and Gain-of-Function Mutations on Salivary Tumors in MMTV-Hras Transgenic Mice

    PubMed Central

    Jiang, Dadi; Dumur, Catherine I.; Massey, H. Davis; Ramakrishnan, Viswanathan; Subler, Mark A.; Windle, Jolene J.

    2015-01-01

    p53 is an important tumor suppressor gene which is mutated in ~50% of all human cancers. Some of these mutants appear to have acquired novel functions beyond merely losing wild-type functions. To investigate these gain-of-function effects in vivo, we generated mice of three different genotypes: MMTV-Hras/p53+/+, MMTV-Hras/p53-/-, and MMTV-Hras/p53R172H/R172H. Salivary tumors from these mice were characterized with regard to age of tumor onset, tumor growth rates, cell cycle distribution, apoptotic levels, tumor histopathology, as well as response to doxorubicin treatment. Microarray analysis was also performed to profile gene expression. The MMTV-Hras/p53-/- and MMTV-Hras/p53R172H/R172H mice displayed similar properties with regard to age of tumor onset, tumor growth rates, tumor histopathology, and response to doxorubicin, while both groups were clearly distinct from the MMTV-Hras/p53+/+ mice by these measurements. In addition, the gene expression profiles of the MMTV-Hras/p53-/- and MMTV-Hras/p53R172H/R172H tumors were tightly clustered, and clearly distinct from the profiles of the MMTV-Hras/p53+/+ tumors. Only a small group of genes showing differential expression between the MMTV-Hras/p53-/- and MMTV-Hras/p53R172H/R172H tumors, that did not appear to be regulated by wild-type p53, were identified. Taken together, these results indicate that in this MMTV-Hras-driven salivary tumor model, the major effect of the p53 R172H mutant is due to the loss of wild-type p53 function, with little or no gain-of-function effect on tumorigenesis, which may be explained by the tissue- and tumor type-specific properties of this gain-of-function mutant of p53. PMID:25695772

  8. Comparison of effects of p53 null and gain-of-function mutations on salivary tumors in MMTV-Hras transgenic mice.

    PubMed

    Jiang, Dadi; Dumur, Catherine I; Massey, H Davis; Ramakrishnan, Viswanathan; Subler, Mark A; Windle, Jolene J

    2015-01-01

    p53 is an important tumor suppressor gene which is mutated in ~50% of all human cancers. Some of these mutants appear to have acquired novel functions beyond merely losing wild-type functions. To investigate these gain-of-function effects in vivo, we generated mice of three different genotypes: MMTV-Hras/p53(+/+), MMTV-Hras/p53(-/-), and MMTV-Hras/p53R172H/R172H. Salivary tumors from these mice were characterized with regard to age of tumor onset, tumor growth rates, cell cycle distribution, apoptotic levels, tumor histopathology, as well as response to doxorubicin treatment. Microarray analysis was also performed to profile gene expression. The MMTV-Hras/p53(-/-) and MMTV-Hras/p53R172H/R172H mice displayed similar properties with regard to age of tumor onset, tumor growth rates, tumor histopathology, and response to doxorubicin, while both groups were clearly distinct from the MMTV-Hras/p53(+/+) mice by these measurements. In addition, the gene expression profiles of the MMTV-Hras/p53(-/-) and MMTV-Hras/p53(R172H/R172H) tumors were tightly clustered, and clearly distinct from the profiles of the MMTV-Hras/p53(+/+) tumors. Only a small group of genes showing differential expression between the MMTV-Hras/p53(-/-) and MMTV-Hras/p53(R172H/R172H) tumors, that did not appear to be regulated by wild-type p53, were identified. Taken together, these results indicate that in this MMTV-Hras-driven salivary tumor model, the major effect of the p53 R172H mutant is due to the loss of wild-type p53 function, with little or no gain-of-function effect on tumorigenesis, which may be explained by the tissue- and tumor type-specific properties of this gain-of-function mutant of p53.

  9. Codon 249 mutation of the p53 gene is a rare event in hepatocellular carcinomas from ethnic Chinese in Singapore.

    PubMed Central

    Shi, C. Y.; Phang, T. W.; Lin, Y.; Wee, A.; Li, B.; Lee, H. P.; Ong, C. N.

    1995-01-01

    The present study characterised p53 mutations in 44 hepatocellular carcinomas (HCCs) from Chinese patients residing in a high-incidence area. Twelve point mutations (27%) were detected in tumour tissues using single-strand conformation polymorphism analysis followed by direct DNA sequencing. Remarkably, no mutations were observed at codon 249. This is in contrast to HCCs from other high HCC incidence areas with endemic aflatoxin exposures, in which codon 249 is a mutational hot spot. It is therefore suggested that risk factors other than dietary exposure to aflatoxin may contribute to the high HCC incidence in Singapore. Images Figure 1 Figure 2 Figure 3 PMID:7599044

  10. P53 gene mutations in breast cancers in Midwestern U.S. women: Null as well as missense-type mutations are associated with poor prognosis

    SciTech Connect

    Blaszyk, H.; Hartmann, A.; Saitoh, S.

    1994-09-01

    Differences in patterns of p53 gene mutation in different types of cancers support the idea that analysis of acquired alterations in this gene will be useful as a {open_quotes}mutagen test{close_quotes}. We are studying the pattern of p53 gene mutation in sporadic breast carcinomas in high and low risk populations. All translated exons and adjacent splice regions have been analyzed in 53 primary breast cancers from Midwestern U.S. Caucasian women. A total of 21 mutations were found in exons 2-11 and splice regions (39.6%). The mutations include 8 missense, 4 nonsense, 1 splice site point mutation, and 8 microdeletions. Comparisons of the pattern of mutations within exons 5-9 show that the frequency of missense mutations (44%) was lower in breast cancers of U.S. Midwestern women than in most tumor types and in breast cancers in other populations. Compared to breast cancers reported in a Scottish population, Midwestern U.S. women have a high frequency of microdeletion mutations (p=0.006) and a low frequency of G:C-T:A transversions (p=0.046). These findings suggest that environmental or endogenous factors contribute to p53 mutagenesis in mammary tissue to different extents among different populations. The presence of a mutation was associated with shorter time to disease recurrence (p=0.05) and shorter survival (p=0.003) (median duration of follow-up 19 months). Both putative dominant negative missense-type mutations (missense and in-frame microdeletions; p=0.001) and null mutations (hemizygous nonsense and frameshift mutations; p=0.007) were associated with poor prognosis. Thus, tumors with missense p53 mutations associated with altered binding to other proteins, altered transcriptional regulation and a dramatic increase in p53 protein concentration have similar clinical outcomes to tumors with null mutations associated with truncated or garbled proteins.

  11. 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

  12. TP53 mutations in astrocytic gliomas: an association with histological grade, TP53 codon 72 polymorphism and p53 expression.

    PubMed

    Faria, Mario H G; Neves Filho, Eduardo H C; Alves, Markenia K S; Burbano, Rommel M R; de Moraes Filho, Manoel O; Rabenhorst, Silvia H B

    2012-11-01

    TP53 mutations and polymorphisms have been widely related to many cancers as long as these alterations may impair its capacity to induce cell cycle arrest, DNA repair mechanisms, and apoptosis. Although TP53 alterations have been studied in astrocytic tumors, there is a lack of analysis considering specific TP53 mutations and their associations with p53 immunostainning, polymorphisms and their significance among the histological grades. Thus, we analyzed TP53 alterations in exons 2-11, including the codon 72 polymorphism, using DNA sequencing in 96 astrocytic gliomas (18 grade I, 20 grade II, 14 grade III, and 44 grade IV). Also, immunohistochemistry was assessed to evaluate the p53 protein expression. In this study, we found that the higher histological grades were statistically associated with TP53 mutations. Some of these mutations, such as TP53 P98T and TP53 G244S, seemed to be a specific marker for the higher grades, and the TP53 E286K mutation appears to be a World Health Organization grade III-IV progression marker. Also, the TP53 P98T mutation, in exon 4, is very likely to be important on the stabilization of the p53 protein, leading to its immunopositivity and it is potentially associated with the TP53 72Pro/Pro genotype.

  13. 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.

  14. Mutations of APC, K-ras, and p53 are associated with specific chromosomal aberrations in colorectal adenocarcinomas.

    PubMed

    Leslie, Amy; Pratt, Norman R; Gillespie, Karen; Sales, Mark; Kernohan, Neil M; Smith, Gillian; Wolf, C Roland; Carey, Francis A; Steele, Robert J C

    2003-08-01

    It is widely accepted that both large-scale chromosomal abnormalities and mutation of specific genes, such as APC, K-ras, and/or p53, occur in the majority of colorectal adenocarcinomas. Whether or not a relationship exists between these different forms of genetic abnormalities was previously unknown. Using comparative genomic hybridization and mutational analysis of APC, K-ras, and p53 to evaluate 50 colorectal adenocarcinomas, we have shown that mutation of p53 is significantly associated with gain of 20q, 13q, and 8q and loss of 18q (P = 0.000, 0.02, 0.044, and 0.001, respectively). Conversely, APC mutation did not associate with any of the above-mentioned aberrations but did associate significantly with gain of 7p (P = 0.01). Gain of chromosomal arm 12p, although a less common aberration, was significantly associated with K-ras mutation (P = 0.011). The associations we have described should refine the search for candidate genes underlying chromosomal aberrations and assist in the definition of distinct pathways in colorectal tumorigenesis.

  15. Mutability of p53 hotspot codons to benzo(a)pyrene diol epoxide (BPDE) and the frequency of p53 mutations in nontumorous human lung.

    PubMed

    Hussain, S P; Amstad, P; Raja, K; Sawyer, M; Hofseth, L; Shields, P G; Hewer, A; Phillips, D H; Ryberg, D; Haugen, A; Harris, C C

    2001-09-01

    p53 mutations are common in lung cancer. In smoking-associated lung cancer,the occurrence of G:C to T:A transversions at hotspot codons, e.g., 157, 248, 249,and 273, has been linked to the presence of carcinogenic chemicalsin tobacco smoke including polycyclic aromatic hydrocarbons suchas benzo(a)pyrene (BP). In the present study, we have used a highly sensitive mutation assay to determine the p53 mutation load in nontumorous human lung and to study the mutability of p53 codons 157, 248, 249, and 250 to benzo(a)pyrene-diol-epoxide (BPDE), an active metabolite of BP in human bronchial epithelial BEAS-2B cells. We determined the p53 mutational load at codons 157, 248, 249, and 250 in nontumorous peripheral lung tissue either from lung cancer cases among smokers or noncancer controls among smokers and nonsmokers. A 5-25-fold higher frequency of GTC(val) to TTC(phe) transversions at codon 157 was found in nontumorous samples (57%) from cancer cases (n = 14) when compared with noncancer controls (n = 8; P < 0.01). Fifty percent (7/14) of the nontumorous samples from lung cancer cases showed a high frequency of codon 249 AGG(arg) to AGT(ser) mutations (P < 0.02). Four of these seven samples with AGT(ser) mutations also showed a high frequency of codon 249 AGG(arg) to ATG(met) mutations, whereas only one sample showed a codon 250 CCC to ACC transversion. Tumor tissue from these lung cancer cases (38%) contained p53 mutations but were different from the above mutations found in the nontumorous pair. Noncancer control samples from smokers or nonsmokers did not contain any detectable mutations at codons 248, 249, or 250. BEAS-2B bronchial epithelial cells exposed to doses of 0.125, 0.5, and 1.0 microM BPDE, showed G:C to T:A transversions at codon 157 at a frequency of 3.5 x 10(-7), 4.4 x 10(-7), and 8.9 x 10(-7), respectively. No mutations at codon 157 were found in the DMSO-treated controls. These doses of BPDE induced higher frequencies, ranging from 4-12-fold, of G:C to

  16. Secondary breast cancer in patients presenting with osteosarcoma: possible involvement of germline p53 mutations.

    PubMed

    Russo, C L; McIntyre, J; Goorin, A M; Link, M P; Gebhardt, M C; Friend, S H

    1994-01-01

    Second malignancies following treatment for osteosarcoma are unusual. Breast cancer occurring in patients with osteosarcoma has been reported following therapeutic chest irradiation. We now report three cases of breast cancer occurring in young women who were successfully treated for osteosarcoma. These women had not received therapeutic chest irradiation and in two of the three women there was no family history of breast cancer. Peripheral blood was available for study from one case. Of import, this case demonstrated a germline mutation in exon 7 of the tumor suppressor gene, p53. The mutation was detected by constant denaturing gradient gel electrophoresis and confirmed by DNA sequencing. In this particular patient, inactivation of the p53 gene may be involved in the development of both the first and second malignancy.

  17. APC, K-ras, and p53 gene mutations in colorectal cancer patients: correlation to clinicopathologic features and postoperative surveillance.

    PubMed

    Hsieh, Jan-Sing; Lin, Shiu-Ru; Chang, Mei-Yin; Chen, Fang-Ming; Lu, Chien-Yu; Huang, Tsung-Jen; Huang, Yu-Sheng; Huang, Che-Jen; Wang, Jaw-Yuan

    2005-04-01

    Current researches have proposed a genetic model for colorectal cancer (CRC), in which the sequential accumulation of mutations in specific cancer-related genes, including adenomatous polyposis coli (APC), K-ras, and p53, drives the transition from normal epithelium through increasing adenomatous dysplasia to colorectal cancer. To identify patients with an increased risk of tumor recurrence or metastasis and evaluate the prognostic values of APC, K-ras, and p53 gene mutations, we investigated the frequency of these three mutated genes in tumors and sera of CRC patients. APC, K-ras, and p53 gene mutations in primary tumor tissues and their paired preoperative serum samples of 118 CRC patients were detected by using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, followed by direct DNA sequencing of the PCR-amplified genomic DNA. Subsequently, serum molecular markers were analyzed for their correlation with patients' clinicopathologic features and presence of postoperative recurrence/metastasis. We did not observe any significant difference in the association of APC or K-ras or p53 gene mutations in primary tumors with patients' demographic data (all were P > 0.05). In contrast, both serum APC and p53 molecular markers were closely correlated with lymph node metastasis and TNM stage (both P < 0.05). Moreover, the serum overall molecular markers (at least one of the three markers) were prominently associated with depth of tumor invasion (P = 0.033), lymph node metastasis (P < 0.001), and TNM stage (P < 0.001). In addition, a significantly higher postoperative metastasis/recurrence rate in patients positive for overall molecular markers compared to those negative for these molecular markers were also demonstrated (P < 0.001). APC and K-ras molecular markers were more frequently observed in patients with locoregional metastasis (both P < 0.05), while p53 molecular marker was usually detected in the cases of peritoneal metastasis (P

  18. Structure and Function of p53-DNA Complexes with Inactivation and Rescue Mutations: A Molecular Dynamics Simulation Study

    PubMed Central

    Kamaraj, Balu; Bogaerts, Annemie

    2015-01-01

    The tumor suppressor protein p53 can lose its function upon DNA-contact mutations (R273C and R273H) in the core DNA-binding domain. The activity can be restored by second-site suppressor or rescue mutations (R273C_T284R, R273H_T284R, and R273H_S240R). In this paper, we elucidate the structural and functional consequence of p53 proteins upon DNA-contact mutations and rescue mutations and the underlying mechanisms at the atomic level by means of molecular dynamics simulations. Furthermore, we also apply the docking approach to investigate the binding phenomena between the p53 protein and DNA upon DNA-contact mutations and rescue mutations. This study clearly illustrates that, due to DNA-contact mutants, the p53 structure loses its stability and becomes more rigid than the native protein. This structural loss might affect the p53-DNA interaction and leads to inhibition of the cancer suppression. Rescue mutants (R273C_T284R, R273H_T284R and R273H_S240R) can restore the functional activity of the p53 protein upon DNA-contact mutations and show a good interaction between the p53 protein and a DNA molecule, which may lead to reactivate the cancer suppression function. Understanding the effects of p53 cancer and rescue mutations at the molecular level will be helpful for designing drugs for p53 associated cancer diseases. These drugs should be designed so that they can help to inhibit the abnormal function of the p53 protein and to reactivate the p53 function (cell apoptosis) to treat human cancer. PMID:26244575

  19. Structure and Function of p53-DNA Complexes with Inactivation and Rescue Mutations: A Molecular Dynamics Simulation Study.

    PubMed

    Kamaraj, Balu; Bogaerts, Annemie

    2015-01-01

    The tumor suppressor protein p53 can lose its function upon DNA-contact mutations (R273C and R273H) in the core DNA-binding domain. The activity can be restored by second-site suppressor or rescue mutations (R273C_T284R, R273H_T284R, and R273H_S240R). In this paper, we elucidate the structural and functional consequence of p53 proteins upon DNA-contact mutations and rescue mutations and the underlying mechanisms at the atomic level by means of molecular dynamics simulations. Furthermore, we also apply the docking approach to investigate the binding phenomena between the p53 protein and DNA upon DNA-contact mutations and rescue mutations. This study clearly illustrates that, due to DNA-contact mutants, the p53 structure loses its stability and becomes more rigid than the native protein. This structural loss might affect the p53-DNA interaction and leads to inhibition of the cancer suppression. Rescue mutants (R273C_T284R, R273H_T284R and R273H_S240R) can restore the functional activity of the p53 protein upon DNA-contact mutations and show a good interaction between the p53 protein and a DNA molecule, which may lead to reactivate the cancer suppression function. Understanding the effects of p53 cancer and rescue mutations at the molecular level will be helpful for designing drugs for p53 associated cancer diseases. These drugs should be designed so that they can help to inhibit the abnormal function of the p53 protein and to reactivate the p53 function (cell apoptosis) to treat human cancer.

  20. MOLECULAR MECHANISMS OF FUNCTIONAL RESCUE MEDIATED BY P53 TUMOR SUPPRESSOR MUTATIONS

    PubMed Central

    Tan, Yu-Hong; Chen, Y. Morris; Ye, Xiang; Lu, Qiang; Tretyachenko-Ladokhina, Vira; Yang, Wei; Senear, Donald F.; Luo, Ray

    2009-01-01

    We have utilized both molecular dynamics simulations and solution biophysical measurements to investigate the rescue mechanism of mutation N235K, which plays a key role in the recently identified global suppressor motif of K235/Y239/R240 in the human p53 DNA-binding domain (DBD). Previous genetic analysis indicates that N235K alone rescues five out of six destabilized cancer mutants. However, the solution biophysical measurement shows that N235K generates only a slight increase to the stability of DBD, implying a rescue mechanism that is not a simple additive contribution to thermodynamic stability. Our molecular simulations show that the N235K substitution generates two non-native salt bridges with residues D186 and E198. We find that the nonnative salt bridges, D186-K235 and E198-K235, and a native salt bridge, E171-R249, are mutually exclusive, thus resulting in only a marginal increase in stability as compared to the wild type protein. When a destabilized V157F is paired with N235K, the native salt bridge E171-R249 is retained. In this context, the non-native salt bridges, D186-K235 and E198-K235, produce a net increase in stability as compared to V157F alone. A similar rescue mechanism may explain how N235K stabilize other highly unstable β-sandwich cancer mutants. PMID:19748724

  1. The carcinogenic air pollutant 3-nitrobenzanthrone induces GC to TA transversion mutations in human p53 sequences.

    PubMed

    vom Brocke, Jochen; Krais, Annette; Whibley, Catherine; Hollstein, Monica C; Schmeiser, Heinz H

    2009-01-01

    3-Nitrobenzanthrone (3-NBA) is a potent mutagen and a suspected human carcinogen present in particulate matter of diesel exhaust and ambient air pollution. Employing an assay with human p53 knock-in (Hupki) murine embryonic fibroblasts (HUFs), we examined p53 mutations induced by 3-NBA and its active metabolite, N-hydroxy-3-aminobenzanthrone (N-OH-3-ABA). Twenty-nine immortalized cultures (cell lines) from 89 HUF primary cultures exposed at passage 1 for 5 days to 2 microM 3-NBA harboured 22 different mutations in the human DNA-binding domain sequence of the Hupki p53 tumour suppressor gene. The most frequently observed mutation was GC to TA transversion (46%), corroborating previous mutation studies with 3-NBA, and consistent with the presence of persistent 3-NBA-guanosine adducts found in DNA of exposed rodents. Six of the transversions found solely in 3-NBA-treated HUFs have not been detected thus far in untreated HUFs, but have been found repeatedly in human lung tumours. (32)P-post-labelling adduct analysis of DNA from HUF cells treated with 2 microM 3-NBA for 5 days showed a pattern similar to that found in vivo, indicating the metabolic competence of HUF cells to metabolize 3-NBA to electrophilic intermediates. Total DNA binding was 160 +/- 56 per 10(7) normal nucleotides with N(2)-guanosine being the major adduct. In contrast, identical treatment with N-OH-3-ABA resulted in a 100-fold lower level of specific DNA adducts and no carcinogen-specific mutation pattern in the Hupki assay. This indicates that the level of DNA adduct formation by the mutagen is critical to obtain specific mutation spectra in the assay. Our results are consistent with previous experiments in Muta Mouse and are compatible with the possibility that diesel exhaust exposure contributes to mutation load in humans and to lung cancer risk.

  2. Cluster Analysis of p53 Binding Site Sequences Reveals Subsets with Different Functions

    PubMed Central

    Lim, Ji-Hyun; Latysheva, Natasha S.; Iggo, Richard D.; Barker, Daniel

    2016-01-01

    p53 is an important regulator of cell cycle arrest, senescence, apoptosis and metabolism, and is frequently mutated in tumors. It functions as a tetramer, where each component dimer binds to a decameric DNA region known as a response element. We identify p53 binding site subtypes and examine the functional and evolutionary properties of these subtypes. We start with over 1700 known binding sites and, with no prior labeling, identify two sets of response elements by unsupervised clustering. When combined, they give rise to three types of p53 binding sites. We find that probabilistic and alignment-based assessments of cross-species conservation show no strong evidence of differential conservation between types of binding sites. In contrast, functional analysis of the genes most proximal to the binding sites provides strong bioinformatic evidence of functional differentiation between the three types of binding sites. Our results are consistent with recent structural data identifying two conformations of the L1 loop in the DNA binding domain, suggesting that they reflect biologically meaningful groups imposed by the p53 protein structure. PMID:27812278

  3. R280T mutation of p53 gene promotes proliferation of human glioma cells through GSK-3β/PTEN pathway.

    PubMed

    Lin, Chenli; Liang, Yinji; Zhu, Huili; Zhang, Jijun; Zhong, Xueyun

    2012-10-31

    p53 mutation is associated with "gain-of-function" capabilities of human cancers. We aim to identify p53 mutations in human glioma cells and to explore the potential mechanism for mutant p53-promoted cellular growth. Whole genomic DNA was isolated from SWO-38, a human glioma cell line and amplified for the region of exons 5, 6, and 8 in p53 gene using polymerase chain reaction (PCR). By means of direct sequencing of PCR products and alignment analysis using BLAST database, a mutation of G to C transition at codon 280 of p53 exon 8 (AGA→ACA), i.e. R280T was detected in SWO-38 cells. Knockdown of R280T mutant p53 by RNA interference inhibited the GSK-3β/PTEN associated cell proliferation, and PI3K/Akt but not Wnt/β-catenin signaling pathway was involved in this process. Furthermore, depletion or overexpression of PTEN alone did not affect cell proliferation and cell cycle, implicating the impairment of PTEN function in SWO-38 cells. However, knockdown of both PTEN and p53 mutation could significantly rescue the p53 depletion-mediated growth inhibition, suggesting that the R280T mutation in glioma may promote the proliferation through an underlying mechanism related to PTEN. Our observations indicate that the R280T mutation of p53 regulates the proliferation of human glioma cells related to the GSK-3β/PTEN pathway. These findings provide valuable insights for better understanding the molecular mechanism of uncontrolled growth of glioma cells.

  4. Suppression of inhibitor of differentiation 2, a target of mutant p53, is required for gain-of-function mutations.

    PubMed

    Yan, Wensheng; Liu, Gang; Scoumanne, Ariane; Chen, Xinbin

    2008-08-15

    Overexpression of mutant p53 is a common theme in human tumors, suggesting a tumor-promoting gain-of-function for mutant p53. To elucidate whether and how mutant p53 acquires its gain-of-function, mutant p53 is inducibly knocked down in the SW480 colon cancer cell line, which contains mutant p53(R273H/P309S), and the MIA PaCa-2 pancreatic cancer cell line, which contains mutant p53(R248W). We found that knockdown of mutant p53 markedly inhibits cell proliferation. In addition, knockdown of mutant p53 sensitizes tumor cells to growth suppression by various chemotherapeutic drugs. To determine whether a gene involved in cell growth and survival is regulated by mutant p53, gene expression profiling analysis was performed and showed that the expression level of Id2, a member of the inhibitor of differentiation (Id) family, was markedly increased upon knockdown of mutant p53. To confirm this, Northern blot analysis was performed and showed that the expression level of Id2 was regulated by various mutant p53s in multiple cell lines. In addition, we found that the Id2 promoter is responsive to mutant but not wild-type p53, and mutant p53 binds to the Id2 promoter. Consistent with these observations, expression of endogenous Id2 was found to be inhibited by exogenous mutant p53 in p53-null HCT116 cells. Finally, we showed that knockdown of Id2 can restore the proliferative potential of tumor cells inhibited by withdrawal of mutant p53. Together, these findings suggest that one mechanism by which mutant p53 acquires its gain-of-function is through the inhibition of Id2 expression.

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

    PubMed Central

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

    1999-01-01

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

  6. Cooperative action of germ-line mutations in decorin and p53 accelerates lymphoma tumorigenesis.

    PubMed

    Iozzo, R V; Chakrani, F; Perrotti, D; McQuillan, D J; Skorski, T; Calabretta, B; Eichstetter, I

    1999-03-16

    Ectopic expression of decorin in a wide variety of transformed cells results in growth arrest and the inability to generate tumors in nude mice. This process is caused by a decorin-mediated activation of the epidermal growth factor receptor, which leads to a sustained induction of endogenous p21(WAF1/CIP1) (the cyclin-dependent kinase inhibitor p21) and growth arrest. However, mice harboring a targeted disruption of the decorin gene do not develop spontaneous tumors. To test the role of decorin in tumorigenesis, we generated mice lacking both decorin and p53, an established tumor-suppressor gene. Mice lacking both genes showed a faster rate of tumor development and succumbed almost uniformly to thymic lymphomas within 6 months [mean survival age (T50) approximately 4 months]. Mice harboring one decorin allele and no p53 gene developed the same spectrum of tumors as the double knockout animals, but had a survival rate similar to the p53 null animals (T50 approximately 6 months). Ectopic expression of decorin in thymic lymphoma cells isolated from double mutant animals markedly suppressed their colony-forming ability. When these lymphoma cells were cocultured with fibroblasts derived from either wild-type or decorin null embryos, the cells grew faster in the absence of decorin. Moreover, exogenous decorin proteoglycan or its protein core significantly retarded their growth in vitro. These results indicate that the lack of decorin is permissive for lymphoma tumorigenesis in a mouse model predisposed to cancer and suggest that germ-line mutations in decorin and p53 may cooperate in the transformation of lymphocytes and ultimately lead to a more aggressive phenotype by shortening the tumor latency.

  7. 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

  8. Rat p53 gene mutations in primary Zymbal gland tumors induced by 2-amino-3-methylimidazo[4,5-f]quinoline, a food mutagen.

    PubMed Central

    Makino, H; Ishizaka, Y; Tsujimoto, A; Nakamura, T; Onda, M; Sugimura, T; Nagao, M

    1992-01-01

    There are reports of p53 gene mutations in various human cancers but not in rat tumor cell lines or rat primary tumor tissue. We found a p53 gene mutation in a cell line of a spontaneous squamous cell carcinoma of the rat Zymbal gland, SCC131, at codon 171 by direct sequencing of cDNA fragments amplified by PCR. We tested for p53 gene mutations in 15 primary Zymbal gland tumors induced by 2-amino-3-methylimidazo[4,5-f]quinoline by single-strand conformation polymorphism analysis of the PCR-amplified cDNA products. Samples of four tumors showed mobility shifts. Direct sequencing revealed that all these tumors had mutations in conserved regions or in scattered conserved residues. Single-strand conformation polymorphism analysis of cDNA suggested that mRNA from the wild-type allele of the p53 gene was not present in tumor cells of three of four positive cases, although genomic DNA analysis indicated that the wild-type allele was retained in all the cases. All mutations were found at a guanine base: three mutations were guanine----pyrimidine transversions and one was a deletion of a guanine base within a G+C-rich sequence. These findings indicate that 2-amino-3-methylimidazo[4,5-f]quinoline may be directly involved in induction of these mutations by forming DNA adducts at various sites in the p53 gene. Images PMID:1594584

  9. A comparative study of detection of p53 mutations in human breast cancer by flow cytometry, single-strand conformation polymorphism and genomic sequencing.

    PubMed Central

    Chakravarty, G.; Redkar, A.; Mittra, I.

    1996-01-01

    The accuracy of immunodetection by dual parameter flow cytometry (FCM), polymerase chain reaction-mediated single strand conformation polymorphism (PCR-SSCP) and genomic sequencing to detect p53 mutations were compared. Analysis by the last two techniques was restricted to exons 5-8. Initially, 110 breast tumours were screened for p53 expression by FCM. Seventy (64%) of tumours were immunopositive. Fifteen highly immunopositive and 15 completely immunonegative tumours were selected for further analysis by PCR-SSCP and genomic sequencing. Eleven out of 15 immunopositive tumours were found to have mutation by PCR-SSCP. Genomic sequencing confirmed the presence of mutation in 10 of these 11 immunopositive tumours. Therefore, four immunopositive tumours failed to show mutation by SSCP and five by genomic sequencing. Of the 15 immunonegative tumours, one showed mutation by both PCR-SSCP and genomic sequencing and one tumour has undergone deletion of the p53 gene. Overall, immunoreactivity correlated with both PCR-SSCP and genomic sequencing in 80% of cases (24/30), and there was 96.5% (28/29) concordance between PCR-SSCP and genomic sequencing. We conclude that there is good concordance between mutations detected by PCR-SSCP and genomic sequencing, but immunochemical detection of p53 overexpression is not an absolute indicator of p53 gene mutation. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:8883402

  10. IARC Database of p53 gene mutations in human tumors and cell lines: updated compilation, revised formats and new visualisation tools.

    PubMed Central

    Hainaut, P; Hernandez, T; Robinson, A; Rodriguez-Tome, P; Flores, T; Hollstein, M; Harris, C C; Montesano, R

    1998-01-01

    Since 1989, about 570 different p53 mutations have been identified in more than 8000 human cancers. A database of these mutations was initiated by M. Hollstein and C. C. Harris in 1990. This database originally consisted of a list of somatic point mutations in the p 53 gene of human tumors and cell lines, compiled from the published literature and made available in a standard electronic form. The database is maintained at the International Agency for Research on Cancer (IARC) and updated versions are released twice a year (January and July). The current version (July 1997) contains records on 6800 published mutations and will surpass the 8000 mark in the January 1998 release. The database now contains information on somatic and germline mutations in a new format to facilitate data retrieval. In addition, new tools are constructed to improve data analysis, such as a Mutation Viewer Java applet developed at the European Bioinformatics Institute (EBI) to visualise the location and impact of mutations on p53 protein structure. The database is available in different electronic formats at IARC (http://www.iarc. fr/p53/homepage.htm ) or from the EBI server (http://www.ebi.ac.uk ). The IARC p53 website also provides reports on database analysis and links with other p53 sites as well as with related databases. In this report, we describe the criteria for inclusion of data, the revised format and the new visualisation tools. We also briefly discuss the relevance of p 53 mutations to clinical and biological questions. PMID:9399837

  11. [Correlation between RARbeta gene promoter methylation and P53 gene mutations in non-small cell lung cancer].

    PubMed

    Tan, Cong; Jin, Yong-tang; Xu, He-yun; Zhang, Chen-ye; Zhang, Hu; Zhang, Wei-min; Chen, Chun-mei; Sun, Xiao-yu

    2012-04-01

    To investigate the correlation between RARbeta gene promoter methylation and P53 gene mutations in non-small cell lung cancer (NSCLC). Promoter methylation of RARbeta and P53 mutations of exons 5 through 9 in 198 resected primary NSCLC tissues were determined by methylation-specific PCR and direct sequencing. RARbeta gene promoter methylation and P53 mutation were detected in 58.1% and 36.4% of tumors, respectively. Both were higher in males than in females and in smokers than in nonsmokers. A higher prevalence of RARbeta promoter methylation was found in patients with advanced stage tumors than those with TNM stage I. P53 gene mutations were more frequent in squamous cell carcinoma and adeno-squamous carcinoma than adenocarcinoma. All such differences were statistically significant (P< 0.05). Frequencies of P53 mutations, including G:C>T:A mutations, transversions and missense mutations were significantly higher in tumors with RARbeta methylation than in those without (P< 0.05). A significantly higher prevalence of RARbeta methylation was found in tumors with only G:C>T:A mutation in P53 gene than those without P53 mutations (P< 0.05). This difference (OR=3.737, 95%CI: 1.414-9.873) was still statistically significant (P< 0.05) in smokers (OR=4.020, 95%CI: 1.263-12.800), squamous cell carcinomas (OR=5.480, 95%CI: 1.400-21.446) or patients with advanced tumors (OR=3.446, 95%CI: 1.054-11.267) after adjusting for age and sex. RARbeta methylation is associated with G:C>T:A mutations in P53 gene in NSCLC.

  12. K-ras, p53 mutations, and microsatellite instability (MSI) in gallbladder cancer.

    PubMed

    Saetta, Angelica A

    2006-06-15

    Despite the considerable progress in understanding the molecular pathology of carcinogenesis, the genetic mechanisms underlying the development and progression of gallbladder cancer (GC) are poorly understood. The survival of GC patients is generally poor. Therefore, it is very useful to define valuable prognostic factors. The most extensively studied oncogenes in gallbladder carcinogenesis are ras, commonly mutated in neoplasms of the gastrointestinal tract. K-ras oncogene is altered in a subset of gallbladder patients and mainly in those having anomalous junction of the pancreaticobiliary tract. Most of the studies of genetic abnormalities in GC have focused on p53 gene. p53 mutation/overexpression and/or LOH is present in more than 50% of gallbladder carcinomas, suggesting an important role in their pathogenesis. However, these results have not any predictive value yet. Moreover, the involvement of an alternative molecular pathway, that of microsatellite instability (MSI), is found in a limited group of GC patients. Additional research is necessary to establish its possible relation to defects of the mismatch repair (MMR) system and its proposed prognostic significance. Further elucidation of the molecular events specific to GC will help to identify novel molecular targets for the diagnosis and clinical management of the patients. Copyright 2006 Wiley-Liss, Inc.

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

    DTIC Science & Technology

    2005-06-01

    Tumor suppressor, p53, DNA-Damage, apoptosis, inhibitors, structural 10 biology, x-ray crystallography, structure-based drug design 16. PRICE CODE 77...Compounds that show favorable properties will be structurally characterized for further analysis (Aim 4). The structure-based drug design approach...often called "rational drug design "), which we are using towards the development of small molecule compounds that might restore function to tumor-derived

  14. Mutations of p53 gene and SV40 sequences in asbestos associated and non-asbestos-associated mesotheliomas.

    PubMed Central

    Mayall, F G; Jacobson, G; Wilkins, R

    1999-01-01

    AIM: To examine mesotheliomas for a possible relation between p53 immunostaining, p53 gene mutation, simian virus 40 (SV40), and asbestos exposure. METHODS: Paraffin sections from 11 mesotheliomas were used for p53 immunostaining and also to extract DNA. This was analysed for the presence of mutations in exons 5 to 8 of the p53 gene using a "cold" single strand conformational polymorphism method, together with sequencing. The DNA from the paraffin sections was also used to search for SV40 sequences. A 105 base pair segment at the 3' of the SV40 large T antigen (Tag) was targeted and any PCR amplification products were sequenced to confirm that they were of SV40 origin. EDAX electron microscopic differential mineral fibre counts were performed on dried lung tissue at a specialist referral centre. RESULTS: The fibre counts showed that seven of the mesotheliomas were associated with abnormally high asbestos exposure. Of these, two showed p53 immunostaining, none showed p53 gene mutation, and five showed SV40. Of the four other mesotheliomas, three showed p53 immunostaining, one showed a (silent) p53 mutation, and none showed SV40. The difference in frequency of SV40 detection was significant at the p < 0.05 level. CONCLUSIONS: Immunostaining for the p53 gene was relatively common but p53 mutations were rare in this series. SV40 virus sequence was detected in five of seven asbestos associated mesotheliomas but in none of the non-asbestos-associated mesotheliomas. This suggests there may be a synergistic interaction between asbestos and SV40 in human mesotheliomas. A study with a larger number of cases is needed to investigate these observations further. Images PMID:10474522

  15. UV and skin cancer: specific p53 gene mutation in normal skin as a biologically relevant exposure measurement.

    PubMed Central

    Nakazawa, H; English, D; Randell, P L; Nakazawa, K; Martel, N; Armstrong, B K; Yamasaki, H

    1994-01-01

    Many human skin tumors contain mutated p53 genes that probably result from UV exposure. To investigate the link between UV exposure and p53 gene mutation, we developed two methods to detect presumptive UV-specific p53 gene mutations in UV-exposed normal skin. The methods are based on mutant allele-specific PCRs and ligase chain reactions and designed to detect CC to TT mutations at codons 245 and 247/248, using 10 micrograms of DNA samples. These specific mutations in the p53 gene have been reported in skin tumors. CC to TT mutations in the p53 gene were detected in cultured human skin cells only after UV irradiation, and the mutation frequency increased with increasing UV dose. Seventeen of 23 samples of normal skin from sun-exposed sites (74%) on Australian skin cancer patients contained CC to TT mutations in one or both of codons 245 and 247/248 of the p53 gene, and only 1 of 20 samples from non-sun-exposed sites (5%) harbored the mutation. None of 15 biopsies of normal skin from non-sun-exposed or intermittently exposed sites on volunteers living in France carried such mutations. Our results suggest that specific p53 gene mutations associated with human skin cancer are induced in normal skin by solar UV radiation. Measurement of these mutations may be useful as a biologically relevant measure of UV exposure in humans and as a possible predictor of risk for skin cancer. Images Fig. 2 Fig. 3 Fig. 4 PMID:8278394

  16. UV and skin cancer: Specific p53 gene mutation in normal skin as a biologically relevant exposure measurement

    SciTech Connect

    Nakazawa, H.; Martel, N.; Armstrong, B.K.; Yamasaki, H. ); English, D.; Randell, P.L. ); Nakazawa, K. )

    1994-01-04

    Many human skin tumors contain mutated p53 genes that probably results from UV exposure. To investigate the link between UV exposure and p53 gene mutation, the authors developed two methods to detect presumptive UV-specific p53 gene mutations in UV-exposed normal skin. The methods are based on mutant allele-specific PCRs and ligase chain reactions and designed to detect CC to TT mutations at codons 245 and 247/248, using 10 [mu]g of DNA samples. These specific mutations in the p53 gene have been reported in skin tumors. CC to TT mutations in the p53 gene were detected in cultured human skin cells only after UV irradiation, and the mutation frequency increased with increasing UV dose. Seventeen of 23 samples of normal skin from sun-exposed sites (74%) on Australian skin cancer patients contained CC to TT mutations in one or both of codons 245 and 247/248 of the p53 gene, and only 1 of 20 samples form non-sun-exposed sites (5%) harbored the mutation. None of 15 biopsies of normal skin from non-sun-exposed or intermittently exposed sites on volunteers living in France carried such mutations. The results suggest that specific p53 gene mutations associated with human skin cancer are induced in normal skin by solar UV radiation. Measurement of these mutations may be useful as a biologically relevant measure of UV exposure in humans and as a possible predictor of risk for skin cancer.

  17. Founder effect for the highly prevalent R337H mutation of tumor suppressor p53 in Brazilian patients with adrenocortical tumors.

    PubMed

    Pinto, Emilia M; Billerbeck, Ana Elisa C; Villares, Maria Candida B F; Domenice, Sorahia; Mendonça, Berenice B; Latronico, Ana Claudia

    2004-10-01

    The incidence of adrenocortical tumors in children from the Southern region of Brazil is higher than in other parts of the world. This fact has been related to the identification of an inherited missense mutation of the p53 (R337H) at high frequency (78-97%) in Brazilian children with adrenocortical tumors. Given the high frequency of this germline mutation in the Brazilian population, it is very likely that the R337H mutation has arisen from a common origin. In this study, we analyzed two highly polymorphic intragenic markers (VNTRp53 and p53CA) in 22 patients (16 children and 6 adults) with adrenocortical tumors carrying the germline R337H mutation and 60 normal individuals using GeneScan Fragment Analysis software. We found six and sixteen different alleles for the VNTRp53 and p53CA polymorphic markers, respectively. Two distinct alleles, both with 122 bp, were found in 56.8% (VNTRp53) and 54.5% (p53CA) of the 44 alleles from patients with adrenocortical tumors associated with the R337H mutation. Differently, these same VNTRp53 and p53CA alleles were found in 18.3% and 14.2% of 120 alleles from normal individuals, respectively (p<0.01, Chi-square test). An identical haplotype for p53 locus was also identified in 95% of the apparently unrelated Brazilian patients with adrenocortical tumors carrying the R337H mutation. In conclusion, we demonstrated a strong evidence of co-segregation between two intragenic polymorphic p53 markers and the germline R337H mutation, indicating that this mutation has originated from a single common ancestral in the great majority of the Brazilian patients with adrenocortical tumors.

  18. 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.

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

    SciTech Connect

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

    2008-12-15

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

  20. Genome-wide analysis of the p53 gene regulatory network in the developing mouse kidney.

    PubMed

    Li, Yuwen; Liu, Jiao; McLaughlin, Nathan; Bachvarov, Dimcho; Saifudeen, Zubaida; El-Dahr, Samir S

    2013-10-16

    Despite mounting evidence that p53 senses and responds to physiological cues in vivo, existing knowledge regarding p53 function and target genes is largely derived from studies in cancer or stressed cells. Herein we utilize p53 transcriptome and ChIP-Seq (chromatin immunoprecipitation-high throughput sequencing) analyses to identify p53 regulated pathways in the embryonic kidney, an organ that develops via mesenchymal-epithelial interactions. This integrated approach allowed identification of novel genes that are possible direct p53 targets during kidney development. We find the p53-regulated transcriptome in the embryonic kidney is largely composed of genes regulating developmental, morphogenesis, and metabolic pathways. Surprisingly, genes in cell cycle and apoptosis pathways account for <5% of differentially expressed transcripts. Of 7,893 p53-occupied genomic regions (peaks), the vast majority contain consensus p53 binding sites. Interestingly, 78% of p53 peaks in the developing kidney lie within proximal promoters of annotated genes compared with 7% in a representative cancer cell line; 25% of the differentially expressed p53-bound genes are present in nephron progenitors and nascent nephrons, including key transcriptional regulators, components of Fgf, Wnt, Bmp, and Notch pathways, and ciliogenesis genes. The results indicate widespread p53 binding to the genome in vivo and context-dependent differences in the p53 regulon between cancer, stress, and development. To our knowledge, this is the first comprehensive analysis of the p53 transcriptome and cistrome in a developing mammalian organ, substantiating the role of p53 as a bona fide developmental regulator. We conclude p53 targets transcriptional networks regulating nephrogenesis and cellular metabolism during kidney development.

  1. Genome-wide analysis of the p53 gene regulatory network in the developing mouse kidney

    PubMed Central

    Li, Yuwen; Liu, Jiao; McLaughlin, Nathan; Bachvarov, Dimcho; El-Dahr, Samir S.

    2013-01-01

    Despite mounting evidence that p53 senses and responds to physiological cues in vivo, existing knowledge regarding p53 function and target genes is largely derived from studies in cancer or stressed cells. Herein we utilize p53 transcriptome and ChIP-Seq (chromatin immunoprecipitation-high throughput sequencing) analyses to identify p53 regulated pathways in the embryonic kidney, an organ that develops via mesenchymal-epithelial interactions. This integrated approach allowed identification of novel genes that are possible direct p53 targets during kidney development. We find the p53-regulated transcriptome in the embryonic kidney is largely composed of genes regulating developmental, morphogenesis, and metabolic pathways. Surprisingly, genes in cell cycle and apoptosis pathways account for <5% of differentially expressed transcripts. Of 7,893 p53-occupied genomic regions (peaks), the vast majority contain consensus p53 binding sites. Interestingly, 78% of p53 peaks in the developing kidney lie within proximal promoters of annotated genes compared with 7% in a representative cancer cell line; 25% of the differentially expressed p53-bound genes are present in nephron progenitors and nascent nephrons, including key transcriptional regulators, components of Fgf, Wnt, Bmp, and Notch pathways, and ciliogenesis genes. The results indicate widespread p53 binding to the genome in vivo and context-dependent differences in the p53 regulon between cancer, stress, and development. To our knowledge, this is the first comprehensive analysis of the p53 transcriptome and cistrome in a developing mammalian organ, substantiating the role of p53 as a bona fide developmental regulator. We conclude p53 targets transcriptional networks regulating nephrogenesis and cellular metabolism during kidney development. PMID:24003036

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

    SciTech Connect

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

    1995-09-01

    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 mutation (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.

  3. The influence of p53 mutation status on the anti-cancer effect of cisplatin in oral squamous cell carcinoma cell lines

    PubMed Central

    2016-01-01

    Objectives The purpose of this study was to evaluate the anti-cancer activity of cisplatin by studying its effects on cell viability and identifying the mechanisms underlying the induction of cell cycle arrest and apoptosis on oral squamous cell carcinoma (OSCC) cell lines with varying p53 mutation status. Materials and Methods Three OSCC cell lines, YD-8 (p53 point mutation), YD-9 (p53 wild type), and YD-38 (p53 deletion) were used. To determine the cytotoxic effect of cisplatin, MTS assay was performed. The cell cycle alteration and apoptosis were analyzed using flow cytometry. Western blot analysis was used to detect the expression of cell cycle alteration- or apoptosis-related proteins as well as p53. Results Cisplatin showed a time- and dose-dependent anti-proliferative effect in all cell lines. Cisplatin induced G2/M cell accumulation in the three cell lines after treatment with 0.5 and 1.0 µg/mL of cisplatin for 48 hours. The proportion of annexin V-FITC-stained cells increased following treatment with cisplatin. The apoptotic proportion was lower in the YD-38 cell line than in the YD-9 or YD-8 cell lines. Also, immunoblotting analysis indicated that p53 and p21 were detected only in YD-8 and YD-9 cell lines after cisplatin treatment. Conclusion In this study, cisplatin showed anti-cancer effects via G2/M phase arrest and apoptosis, with some difference among OSCC cell lines. The mutation status of p53 might have influenced the difference observed among cell lines. Further studies on p53 mutation status are needed to understand the biological behavior and characteristics of OSCCs and to establish appropriate treatment. PMID:28053903

  4. The Cancer-associated K351N Mutation Affects the Ubiquitination and the Translocation to Mitochondria of p53 Protein*

    PubMed Central

    Muscolini, Michela; Montagni, Elisa; Palermo, Vanessa; Di Agostino, Silvia; Gu, Wei; Abdelmoula-Souissi, Salma; Mazzoni, Cristina; Blandino, Giovanni; Tuosto, Loretta

    2011-01-01

    Stress-induced monoubiquitination of p53 is a crucial event for the nuclear-cytoplasm-mitochondria trafficking and transcription-independent pro-apoptotic functions of p53. Although an intact ubiquitination pathway and a functional nuclear export sequence are required for p53 nuclear export, the role of specific residues within this region in regulating both processes remains largely unknown. Here we characterize the mechanisms accounting for the nuclear accumulation of a new point mutation (Lys-351 to Asn) in the nuclear export sequence of p53 identified in a cisplatin-resistant ovarian carcinoma cell line (A2780 CIS). We found that K351N substitution abrogates the monoubiquitination of p53 induced by both Mdm2 and MSL2 E3-ligases. As a consequence, cells expressing p53 K351N mutant showed defects in cisplatin-induced translocation of p53 to mitochondria, Bax oligomerization, and mitochondrial membrane depolarization. These data identify K351N as a critical mutation of p53 that contributes to the development and maintenance of resistance to cisplatin. PMID:21953469

  5. The cancer-associated K351N mutation affects the ubiquitination and the translocation to mitochondria of p53 protein.

    PubMed

    Muscolini, Michela; Montagni, Elisa; Palermo, Vanessa; Di Agostino, Silvia; Gu, Wei; Abdelmoula-Souissi, Salma; Mazzoni, Cristina; Blandino, Giovanni; Tuosto, Loretta

    2011-11-18

    Stress-induced monoubiquitination of p53 is a crucial event for the nuclear-cytoplasm-mitochondria trafficking and transcription-independent pro-apoptotic functions of p53. Although an intact ubiquitination pathway and a functional nuclear export sequence are required for p53 nuclear export, the role of specific residues within this region in regulating both processes remains largely unknown. Here we characterize the mechanisms accounting for the nuclear accumulation of a new point mutation (Lys-351 to Asn) in the nuclear export sequence of p53 identified in a cisplatin-resistant ovarian carcinoma cell line (A2780 CIS). We found that K351N substitution abrogates the monoubiquitination of p53 induced by both Mdm2 and MSL2 E3-ligases. As a consequence, cells expressing p53 K351N mutant showed defects in cisplatin-induced translocation of p53 to mitochondria, Bax oligomerization, and mitochondrial membrane depolarization. These data identify K351N as a critical mutation of p53 that contributes to the development and maintenance of resistance to cisplatin.

  6. Ethanol and aloe emodin alter the p53 mutational spectrum in ultraviolet radiation-induced murine skin tumors.

    PubMed

    Badgwell, Donna B; Walker, Christopher M; Baker, Whitney T; Strickland, Faith M

    2004-03-01

    Mutations in the p53 tumor-suppressor gene contribute to the development of skin cancer, and the spectrum of mutations in this gene correlates with specific physical and chemical carcinogens in the environment. Cosmetics may contain alcohols and/or aloe emodin (AE). Although these compounds are not carcinogenic when applied to the skin, they may increase the carcinogenicity of ultraviolet (UV) radiation. We investigated whether ethanol (EtOH) and AE alone or combined with UV radiation cause mutations in the p53 gene. In the absence of UV radiation, C3H/HeN mice chronically treated for up to 33 wk with AE in 25% EtOH-in-water vehicle or vehicle alone failed to develop tumors and had no mutations in exons 4-8 of the p53 gene. UV radiation alone induced skin tumors, which had mutations predominantly in p53 exons 5 and 8. In contrast, mutations arising in UV + EtOH-or UV + AE-treated groups were more broadly distributed throughout the p53 gene. Mutations were found in exons 4, 6, and 7, as well as in exons 5 and 8. This altered distribution of mutations across the p53 DNA sequence more closely resembles the pattern observed in TP53 from human skin tumors at sun-exposed sites than that in the p53 gene of mice treated with UV alone. Thus, treatment with UV radiation in combination with two chemicals not thought to be carcinogenic, alcohol, and AE results in a broader distribution of mutations in a critical tumor-suppressor gene.

  7. Global analysis of p53-regulated transcription identifies its direct targets and unexpected regulatory mechanisms

    PubMed Central

    Allen, Mary Ann; Andrysik, Zdenek; Dengler, Veronica L; Mellert, Hestia S; Guarnieri, Anna; Freeman, Justin A; Sullivan, Kelly D; Galbraith, Matthew D; Luo, Xin; Kraus, W Lee; Dowell, Robin D; Espinosa, Joaquin M

    2014-01-01

    The p53 transcription factor is a potent suppressor of tumor growth. We report here an analysis of its direct transcriptional program using Global Run-On sequencing (GRO-seq). Shortly after MDM2 inhibition by Nutlin-3, low levels of p53 rapidly activate ∼200 genes, most of them not previously established as direct targets. This immediate response involves all canonical p53 effector pathways, including apoptosis. Comparative global analysis of RNA synthesis vs steady state levels revealed that microarray profiling fails to identify low abundance transcripts directly activated by p53. Interestingly, p53 represses a subset of its activation targets before MDM2 inhibition. GRO-seq uncovered a plethora of gene-specific regulatory features affecting key survival and apoptotic genes within the p53 network. p53 regulates hundreds of enhancer-derived RNAs. Strikingly, direct p53 targets harbor pre-activated enhancers highly transcribed in p53 null cells. Altogether, these results enable the study of many uncharacterized p53 target genes and unexpected regulatory mechanisms. DOI: http://dx.doi.org/10.7554/eLife.02200.001 PMID:24867637

  8. Xeroderma pigmentosum group C gene expression is predominantly regulated by promoter hypermethylation and contributes to p53 mutation in lung cancers.

    PubMed

    Wu, Y-H; Tsai Chang, J-H; Cheng, Y-W; Wu, T-C; Chen, C-Y; Lee, H

    2007-07-19

    Reduced DNA repair capability is associated with developing lung cancer, especially in nonsmokers. XPC participates in the initial recognition of DNA damage during the DNA nucleotide excision repair process. We hypothesize that inactivation of XPC by promoter hypermethylation may play an important role in the reduction of DNA repair capability to cause p53 mutation during lung carcinogenesis. In this report we demonstrate that hypermethylation of 17 CpG islands between -175 and -1 of the XPC promoter correlates very well with XPC expression levels in eight lung cancer cell lines. When cells with hypermethylated XPC promoters were treated with the demethylating agent 5-aza-2'-deoxycytidine, XPC expression was de-repressed. Interestingly, XPC hypermethylation was found in 4 of 5 (80%) lung cancer cell lines harbored p53 mutation, but not observed in two lung cancer cells which had a wild-type p53 gene. Among the analysis of the hypermethylation status of 158 lung tumors, XPC hypermethylation is more common in nonsmokers (39 of 94, 41%) than in smokers (14 of 64, 22%; P=0.010). Additionally, XPC hypermethylation is more often with G --> T or G --> C mutations in the p53 gene. To verify whether XPC inactivation is involved in the occurrence of p53 mutation, XPC gene of A549 cells was knockdown by a small interference RNA and then XPC-inactivated cells were treated with benzo[a]pynrene for different passages. Surprisingly, G --> T mutation in p53 gene at codon 215 was indeed detected in XPC-inactivated A549 cells of passages 15 and confirmed by loss of transcription activity of mdm2. These results show that hypermethylation of the XPC promoter may play a crucial role in XPC inactivation, which may partly contribute to the occurrence of p53 mutations during lung tumorigenesis, especially nonsmokers.

  9. Involvement of p53 mutation and mismatch repair proteins dysregulation in NNK-induced malignant transformation of human bronchial epithelial cells.

    PubMed

    Shen, Ying; Zhang, Shuilian; Huang, Xiaobin; Chen, Kailin; Shen, Jing; Wang, Zhengyang

    2014-01-01

    Genome integrity is essential for normal cellular functions and cell survival. Its instability can cause genetic aberrations and is considered as a hallmark of most cancers. To investigate the carcinogenesis process induced by tobacco-specific carcinogen NNK, we studied the dynamic changes of two important protectors of genome integrity, p53 and MMR system, in malignant transformation of human bronchial epithelial cells after NNK exposure. Our results showed that the expression of MLH1, one of the important MMR proteins, was decreased early and maintained the downregulation during the transformation in a histone modification involved and DNA methylation-independent manner. Another MMR protein PMS2 also displayed a declined expression while being in a later stage of transformation. Moreover, we conducted p53 mutation analysis and revealed a mutation at codon 273 which led to the replacement of arginine by histidine. With the mutation, DNA damage-induced activation of p53 was significantly impaired. We further reintroduced the wild-type p53 into the transformed cells, and the malignant proliferation can be abrogated by inducing cell cycle arrest and apoptosis. These findings indicate that p53 and MMR system play an important role in the initiation and progression of NNK-induced transformation, and p53 could be a potential therapeutic target for tobacco-related cancers.

  10. UV-specific p53 and PTCH mutations in sporadic basal cell carcinoma of sun-exposed skin.

    PubMed

    Ratner, D; Peacocke, M; Zhang, H; Ping, X L; Tsou, H C

    2001-02-01

    UVB irradiation is known to produce DNA damage at mutation hotspots in the p53 tumor suppressor gene, leading to the development of skin cancers. Mutations in the PTCH tumor suppressor gene, which is known to be responsible for the development of nevoid basal cell carcinoma syndrome, have also been identified in sporadic basal cell carcinomas (BCCs). We describe the case of an 80-year-old welder in whom 3 novel p53 mutations, as well as UV-specific PTCH mutations, were detected in two BCC samples from sun-exposed skin. The simultaneous presence of UV-specific p53 and PTCH mutations in the same BCC sample has not previously been reported.

  11. Anti-cancer efficacy of SREBP inhibitor, alone or in combination with docetaxel, in prostate cancer harboring p53 mutations

    PubMed Central

    Li, Xiangyan; Wu, Jason Boyang; Chung, Leland W.K.; Huang, Wen-Chin

    2015-01-01

    Mutant p53 proteins (mutant p53s) have oncogenic gain-of-function properties correlated with tumor grade, castration resistance, and prostate cancer (PCa) tumor recurrence. Docetaxel is a standard first-line treatment for metastatic castration-resistant PCa (mCRPC) after the failure of hormone therapy. However, most mCRPC patients who receive docetaxel experience only transient benefits and rapidly develop incurable drug resistance, which is closely correlated with the p53 mutation status. Mutant p53s were recently reported to regulate the metabolic pathways via sterol regulatory element-binding proteins (SREBPs). Therefore, targeting the SREBP metabolic pathways with docetaxel as a combination therapy may offer a potential strategy to improve anti-tumor efficacy and delay cellular drug resistance in mCRPC harboring mutant p53s. Our previous data showed that fatostatin, a new SREBP inhibitor, inhibited cell proliferation and induced apoptosis in androgen receptor (AR)-positive PCa cell lines and xenograft mouse models. In this study, we demonstrated that mutant p53s activate the SREBP-mediated metabolic pathways in metastatic AR-negative PCa cells carrying mutant p53s. By blocking the SREBP pathways, fatostatin inhibited cell growth and induced apoptosis in metastatic AR-negative PCa cells harboring mutant p53s. Furthermore, the combination of fatostatin and docetaxel resulted in greater proliferation inhibition and apoptosis induction compared with single agent treatment in PCa cells in vitro and in vivo, especially those with mutant p53s. These data suggest for the first time that fatostatin alone or in combination with docetaxel could be exploited as a novel and promising therapy for metastatic PCa harboring p53 mutations. PMID:26512780

  12. Anti-cancer efficacy of SREBP inhibitor, alone or in combination with docetaxel, in prostate cancer harboring p53 mutations.

    PubMed

    Li, Xiangyan; Wu, Jason Boyang; Chung, Leland W K; Huang, Wen-Chin

    2015-12-01

    Mutant p53 proteins (mutant p53s) have oncogenic gain-of-function properties correlated with tumor grade, castration resistance, and prostate cancer (PCa) tumor recurrence. Docetaxel is a standard first-line treatment for metastatic castration-resistant PCa (mCRPC) after the failure of hormone therapy. However, most mCRPC patients who receive docetaxel experience only transient benefits and rapidly develop incurable drug resistance, which is closely correlated with the p53 mutation status. Mutant p53s were recently reported to regulate the metabolic pathways via sterol regulatory element-binding proteins (SREBPs). Therefore, targeting the SREBP metabolic pathways with docetaxel as a combination therapy may offer a potential strategy to improve anti-tumor efficacy and delay cellular drug resistance in mCRPC harboring mutant p53s. Our previous data showed that fatostatin, a new SREBP inhibitor, inhibited cell proliferation and induced apoptosis in androgen receptor (AR)-positive PCa cell lines and xenograft mouse models. In this study, we demonstrated that mutant p53s activate the SREBP-mediated metabolic pathways in metastatic AR-negative PCa cells carrying mutant p53s. By blocking the SREBP pathways, fatostatin inhibited cell growth and induced apoptosis in metastatic AR-negative PCa cells harboring mutant p53s. Furthermore, the combination of fatostatin and docetaxel resulted in greater proliferation inhibition and apoptosis induction compared with single agent treatment in PCa cells in vitro and in vivo, especially those with mutant p53s. These data suggest for the first time that fatostatin alone or in combination with docetaxel could be exploited as a novel and promising therapy for metastatic PCa harboring p53 mutations.

  13. Targeted mutation of p53 and Rb in mesenchymal cells of the limb bud produces sarcomas in mice.

    PubMed

    Lin, Patrick P; Pandey, Manoj K; Jin, Fenghua; Raymond, A Kevin; Akiyama, Haruhiko; Lozano, Guillermina

    2009-10-01

    Mice bearing germ line mutations of p53 develop sarcomas at a significant rate. Since they are susceptible to a variety of other malignancies, they are not ideally suited to the study of sarcomas. To test the possibility that targeted mutation of tumor suppressor genes in early mesenchymal cells would induce formation of sarcomas, the Prx1-cre transgenic mouse was crossed to mice-bearing floxed alleles of p53 and Rb. Mice with homozygous deletion of p53 (Prx1-cre p53(lox/lox)) developed sarcomas in the extremities at a mean time of 50 weeks. Osteosarcomas (OS) were the most common type of sarcoma (61%) followed by poorly differentiated soft tissue sarcomas (PDSTS) (32%). Homozygous deletion of p53 produced sarcomas significantly more rapidly than heterozygous deletion, which resulted in sarcoma formation after a mean of 96 weeks. Mice with homozygous Rb mutation (Prx1-cre Rb(lox/lox)) developed normally and had no ostensible defects in the limbs. In contrast to p53, targeted deletion of Rb did not produce sarcomas in the limbs. However, simultaneous deletion of Rb and p53 accelerated the time to sarcoma formation, and a greater percentage of PDSTS were found. Deletion of p53 in committed osteoblasts by the Col1a1-cre transgenic mouse bearing an osteoblast-specific enhancer resulted in a high percentage of OS. These findings suggest that deletion of p53 in mesenchymal cells that give rise to osteoblasts is a powerful initiator of OS. Deletion of Rb does not initiate sarcoma formation in mice, but it accelerates formation of both soft tissue sarcomas and OS.

  14. 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.

  15. The evaluation of human papillomavirus and p53 gene mutation in benign and malignant conjunctiva and eyelid lesions.

    PubMed

    Joanna, Reszec; Renata, Zalewska; Witold, Pepiński; Małgorzata, Skawronska; Bernaczyk, Piotr; Chyczewski, Lech

    2010-12-01

    Papillomas and squamous cell carcinomas are the most common conjunctival and eyelid lesions. The etiology is still unclear and recently human papillomavirus infection and p53 gene mutation have been taken into consideration. The aim of our study was the evaluation of HPV DNApresence and p53 gene mutation in 45 benign and 38 malignant squamous lesions of the conjunctiva and eyelid. For HPV detection PCR-RFLP and immunohistochemical reaction were used; for p53 gene mutation PCR-SSCP was used. Only 8.8% papillomas, 9.1% squamous cell cancers and 3.7% basal cell cancers (using PCR-RFLP method) and 26.6% papillomas, 7.4% squamous cell cancers and 9.1% basal cell cancers (using immunohisto-chemical reaction) were HPV positive. p53 gene mutation was evaluated in 24.4% papillomas, 54.5% squamous cell cancers and 22.2% basal cell cancers; most commonly in 6 and 7 exon. Human papillomavirus infection, opposite to p53 gene mutation, is not a significant etiological factor of the benign and malignant conjunctival and eyelid lesions development.

  16. Identification of a polymorphic site as a mutational site in exon VI of the mouse p53 gene

    SciTech Connect

    Paunesku, T.; Gemmell, M.A.; Crkvenjakov, R.; Woloschak, G.E.

    1993-07-01

    Sequencing by hybridization techniques are being used to analyze the incidence of specific p53 mutations associated with radiation-induced and spontaneous lymphosarcomas in mice. One sequence difference noted as being a mouse strain-specific polymorphism has been identified through these experiments as being a mutational, rather than a polymorphic, site.

  17. 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…

  18. 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…

  19. Nickel accumulation in lung tissues is associated with increased risk of p53 mutation in lung cancer patients.

    PubMed

    Chiou, Yu-Hu; Wong, Ruey-Hong; Chao, Mu-Rong; Chen, Chih-Yi; Liou, Saou-Hsing; Lee, Huei

    2014-10-01

    Occupational exposure to nickel compounds has been associated with lung cancer. The correlation between high nickel levels and increased risk of lung cancer has been previously reported in a case-control study. This study assessed whether nickel exposure increased the occurrence of p53 mutations due to DNA repair inhibition by nickel. A total of 189 lung cancer patients were enrolled to determine nickel levels in tumor-adjacent normal lung tissues and p53 mutation status in lung tumors through atomic absorption spectrometry and direct sequencing, respectively. Nickel levels in p53 mutant patients were significantly higher than those in p53 wild-type patients. When patients were divided into high- and low-nickel subgroups by median nickel level, the high-nickel subgroup of patients had an odds ratio (OR) of 3.25 for p53 mutation risk relative to the low-nickel subgroup patients. The OR for p53 mutation risk of lifetime non-smokers, particularly females, in the high-nickel subgroup was greater than that in the low-nickel subgroup. To determine whether nickel affected DNA repair capacity, we conducted the host cell reactivation assay in A549 and H1975 lung cancer cells and showed that the DNA repair activity was reduced by nickel chloride in a dose-dependent manner. This was associated with elevated production of hydrogen peroxide-induced 8-oxo-deoxyguanosine. Therefore, increased risk of p53 mutation due to defective DNA repair caused by high nickel levels in lung tissues may be one mechanism by which nickel exposure contributes to lung cancer development, especially in lifetime female non-smokers.

  20. Optimized polymerase chain reaction-based single-strand conformation polymorphism analysis of p53 gene applied to Bulgarian patients with invasive breast cancer.

    PubMed

    Krasteva, M E; Garanina, Z; Georgieva, E I

    2003-11-01

    During the last few decades a substantial amount of evidence has accumulated proving that the abrogation of the normal p53 pathway is a critical step in the initiation and progression of tumors. Decoding the genetic mechanisms involved in carcinogenesis requires screening for consistent genetic tumor alterations, including those concerning the p53 gene. Thus, practical, efficient, and inexpensive techniques for accurate determination of p53 mutational status are needed. Polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis is considered to be a useful tool to investigate the role of the p53 gene in the development and progression of human cancers. The sensitivity of the method can be increased considerably by varying the experimental conditions. Here we demonstrate a scheme of PCR-SSCP optimization for detection of p53 gene mutations of patients with various cancers. Optimal conditions for PCRSSCP of p53 exons 4-9 are reported. Such PCR-SSCP optimization could allow an increase in the sensitivity and reproducibility of the technique and facilitates screening of large series of patients to assess the clinical significance of p53 mutations in human cancers. Using the optimized PCR-SSCP analysis we screened Bulgarian patients with invasive breast cancer for p53 gene mutations and registered a 33.33% frequency of mutations. To date, there are no data concerning the p53 status of Bulgarian breast cancer patients. Screening for p53 gene mutations enables an accurate and routine determination of the p53 status of patients with cancer and may be applied in clinical oncology to cancer diagnosis, prediction of prognosis and response to treatment.

  1. Role of uL3 in Multidrug Resistance in p53-Mutated Lung Cancer Cells

    PubMed Central

    Russo, Annapina; Saide, Assunta; Smaldone, Silvia; Faraonio, Raffaella; Russo, Giulia

    2017-01-01

    Cancer is one of the most common causes of death among adults. Chemotherapy is crucial in determining patient survival and quality of life. However, the development of multidrug resistance (MDR) continues to pose a significant challenge in the management of cancer. In this study, we analyzed the role of human ribosomal protein uL3 (formerly rpL3) in multidrug resistance. Our studies revealed that uL3 is a key determinant of multidrug resistance in p53-mutated lung cancer cells by controlling the cell redox status. We established and characterized a multidrug resistant Calu-6 cell line. We found that uL3 down-regulation correlates positively with multidrug resistance. Restoration of the uL3 protein level re-sensitized the resistant cells to the drug by regulating the reactive oxygen species (ROS) levels, glutathione content, glutamate release, and cystine uptake. Chromatin immunoprecipitation experiments and luciferase assays demonstrated that uL3 coordinated the expression of stress-response genes acting as transcriptional repressors of solute carrier family 7 member 11 (xCT) and glutathione S-transferase α1 (GST-α1), independently of Nuclear factor erythroid 2-related factor 2 (Nrf2). Altogether our results describe a new function of uL3 as a regulator of oxidative stress response genes and advance our understanding of the molecular mechanisms underlying multidrug resistance in cancers. PMID:28273808

  2. Differences in the mutation of the p53 gene in exons 6 and 7 in cervical samples from HIV- and HPV-infected women

    PubMed Central

    2013-01-01

    Background Human Papillomavirus (HPV) infection is a serious problem for human immunodeficiency virus (HIV)-infected women, increases their risk of cervical lesions and cancer. In cervical carcinogenesis, mutations in the p53 gene occur most frequently within exons 5–8. To our knowledge, no previous studies have analyzed mutations in exons 5–8 of the p53 gene in HIV- and HPV-infected women. In our study, we verified these mutations in women with and without cervical abnormalities. Findings The study included 160 women, divided into three groups: (1) 83 HPV- and HIV-infected women (HIV group); (2) 37 HPV-infected/HIV-uninfected (control group); and (3) 40 normal cytology/DNA-HPV negative/HIV-uninfected women (negative control p53 reactions). HPV-DNA was detected using polymerase chain reaction (PCR) and genotyping by PCR-restriction fragment length polymorphism analysis. Using primers for exons 5–8, the mutation of the p53 gene was verified by PCR-single strand conformational polymorphism. The total mutation of the p53 gene in exons 5–8 was not significantly associated with the HIV and control groups. The mutations in exon 7 were the highest in the HIV group (43.8%) and in exon 6 in the control group (57.2%) (p = 0.0793) suggesting a tendency toward differential mutation in exon 7 in the HIV group. Conclusions Our study provides preliminary evidence that the mutation in exon 7 might be an important differentiating factor for cervical carcinogenesis in HIV-infected women. This aspect deserves an additional cross-sectional and longitudinal study using a larger sample size with a higher number of High-grade squamous intraephitelial lesion (HSIL) to observe the evolution of cervical lesions. PMID:24098975

  3. Mutations of p53 gene in hepatocellular carcinoma: roles of hepatitis B virus and aflatoxin contamination in the diet.

    PubMed

    Hsia, C C; Kleiner, D E; Axiotis, C A; Di Bisceglie, A; Nomura, A M; Stemmermann, G N; Tabor, E

    1992-11-04

    Mutations of the p53 tumor suppressor gene have been reported in 50% of patients with hepatocellular carcinoma (HCC) from China and South Africa. These reports suggested an association of p53 mutations with high levels of aflatoxin in the diet. Most studies of p53 and HCC, however, have not fully evaluated the possible role of the hepatitis B virus (HBV). Aflatoxin is a substance produced by food mold that is known to cause HCC in experimental animals. The purpose of this study was to evaluate the relationship of p53 gene mutation to high or low levels of aflatoxin in the diet and to HBV infection. p53 protein and hepatitis B surface antigen (HBsAg) were evaluated by immunohistochemistry using the avidin-biotin-peroxidase system in paraffin-embedded specimens of HCC and of adjacent nontumorous liver tissue from 43 patients. Tissue specimens from three normal human livers were also evaluated. HCCs and adjacent nontumorous liver tissues were obtained from 23 patients from Qidong, China, where aflatoxin levels in the diet are high, and from 20 patients from two regions in the United States (patients from the National Institutes of Health, Bethesda, Md., and Kuakini Medical Center, Honolulu, Hawaii), where aflatoxin levels in the diet are low. Mutant p53 protein was detected in the nuclei of HCCs from 14 (61%) of 23 patients from China and from three (30%) of 10 patients and six (60%) of 10 patients, respectively, from the two regions of the United States. A statistically significant association between detection of mutant p53 protein in HCC cells and the detection of HBsAg in hepatocytes of the adjacent nontumorous liver tissue was observed in patients from China and the United States considered together. Mutations of the tumor suppressor gene p53 in hepatocellular carcinomas are not limited to patients from geographic regions where the ingestion of aflatoxin is high. In many patients, these mutations may be associated with HBV infection. The possible interaction of

  4. Analysis of chromosome 17p13 (p53 locus) alterations in gastric carcinoma cells by dual-color fluorescence in situ hybridization.

    PubMed

    Kobayashi, M; Kawashima, A; Mai, M; Ooi, A

    1996-11-01

    Chromosome 17 and p53 gene locus alterations were determined on 67 gastric carcinomas by dual-color fluorescence in situ hybridization, using probes for centromere 17 and the 17p13.1 (p53 locus). The results were compared with loss of heterozygosity (LOH) at 17p13.3, direct sequencing of exons 5 to 9 of p53, and nuclear overexpression of p53 protein. Deletion of p53 was found in 26 of 67 tumors (39%). All 26 also showed LOH at 17p13.3, frequently overexpressed p53 protein, and had polysomy 17. The functional loss of p53 gene in these tumors, 85% of which were of intestinal type, appears to be caused by both deletion of 17p13.1 and missense mutation of the remaining allele. There were 9 tumors that had neither deletion nor LOH but had a large proportion of cancer cells that overexpressed p53 election. Despite evidence of LOH, there was no p53 deletion in 11 tumors. Finally, 21 tumors, mostly of diffuse type, showed neither deletions, LOH, nor p53 overexpression. Our data suggest that in gastric cancer, deletion of 17p is principally responsible for the allelic loss at the p53 gene and that analysis of deletions by the dual-color fluorescence in situ hybridization is a sensitive and useful approach to clarify chromosomal aberrations.

  5. Enhanced cytotoxicity of PARP inhibition in mantle cell lymphoma harbouring mutations in both ATM and p53

    PubMed Central

    Williamson, Chris T; Kubota, Eiji; Hamill, Jeffrey D; Klimowicz, Alexander; Ye, Ruiqiong; Muzik, Huong; Dean, Michelle; Tu, LiRen; Gilley, David; Magliocco, Anthony M; McKay, Bruce C; Bebb, D Gwyn; Lees-Miller, Susan P

    2012-01-01

    Poly-ADP ribose polymerase (PARP) inhibitors have shown promise in the treatment of human malignancies characterized by deficiencies in the DNA damage repair proteins BRCA1 and BRCA2 and preclinical studies have demonstrated the potential effectiveness of PARP inhibitors in targeting ataxia-telangiectasia mutated (ATM)-deficient tumours. Here, we show that mantle cell lymphoma (MCL) cells deficient in both ATM and p53 are more sensitive to the PARP inhibitor olaparib than cells lacking ATM function alone. In ATM-deficient MCL cells, olaparib induced DNA-PK-dependent phosphorylation and stabilization of p53 as well as expression of p53-responsive cell cycle checkpoint regulators, and inhibition of DNA-PK reduced the toxicity of olaparib in ATM-deficient MCL cells. Thus, both DNA-PK and p53 regulate the response of ATM-deficient MCL cells to olaparib. In addition, small molecule inhibition of both ATM and PARP was cytotoxic in normal human fibroblasts with disruption of p53, implying that the combination of ATM and PARP inhibitors may have utility in targeting p53-deficient malignancies. PMID:22416035

  6. 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

  7. 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...

  8. 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...

  9. Effect of arsenic on p53 mutation and occurrence of teratogenic salamanders: their potential as ecological indicators for arsenic contamination.

    PubMed

    Chang, Jin-Soo; Gu, Man Bock; Kim, Kyoung-Woong

    2009-05-01

    The p53 mutation in salamanders can be used as an indicator of arsenic contamination. The influence of arsenic exposure was studied on mutation of tumor suppressor gene in salamanders collected from several As-contaminated mine areas in Korea. Salamander eggs and larvae were exposed to arsenic in a toxicity test, and teratogenic salamanders found in heavy metal- and As-contaminated water from As-Bi mines were evaluated using PCR-SSCP to determine if they would be useful as an ecological indicator species. Changes in amino acids were shown to have occurred as a result of an arsenic-accumulating event that occurred after the DNA damage. In addition, both of the Hynobius leechii exposed groups were primarily affected by forms of skin damage, changes in the lateral tail/dorsal flexure and/or abnormality teratogenesis. Single-base sense mutation in codons 346 (AAG: Lys to ATG: Met), 224 (TTT: Phe to TTA: Leu), 211 (ATG: Met to AAG: Lys), 244 (TTT: Phe to TTTG: insertion), 245 (Glu GAG to Gln CAG) and 249 (TGT Cys to TGA stop) of the p53 gene were simultaneously found in mutated salamanders. Based on the results of our data illustrating the effect of arsenic exposure on the p53 mutation of salamanders in arsenic-contaminated mine areas, these mutated salamanders can be used as potential ecological indicators in the arsenic-contaminated ecosystems.

  10. A role for sunlight in skin cancer: UV-induced p53 mutations in squamous cell carcinoma.

    PubMed Central

    Brash, D E; Rudolph, J A; Simon, J A; Lin, A; McKenna, G J; Baden, H P; Halperin, A J; Pontén, J

    1991-01-01

    Sunlight is a carcinogen to which everyone is exposed. Its UV component is the major epidemiologic risk factor for squamous cell carcinoma of the skin. Of the multiple steps in tumor progression, those that are sunlight-related would be revealed if they contained mutations specific to UV. In a series of New England and Swedish patients, we find that 14/24 (58%) of invasive squamous cell carcinomas of the skin contain mutations in the p53 tumor suppressor gene, each altering the amino acid sequence. Involvement of UV light in these p53 mutations is indicated by the presence in three of the tumors of a CC----TT double-base change, which is only known to be induced by UV. UV is also implicated by a UV-like occurrence of mutations exclusively at dipyrimidine sites, including a high frequency of C----T substitutions. p53 mutations in internal malignancies do not show these UV-specific mutations. The dipyrimidine specificity also implicates dipyrimidine photoproducts containing cytosine as oncogenic photoproducts. We believe these results identify a carcinogen-related step in a gene involved in the subsequent human cancer. Images PMID:1946433

  11. A role for sunlight in skin cancer: UV-induced p53 mutations in squamous cell carcinoma

    SciTech Connect

    Brash, D.E.; Rudolph, J.A.; Simon, J.A.; Lin, A.; McKenna, G.J. ); Baden, H.P. ); Ponten, J. )

    1991-11-15

    Sunlight is a carcinogen to which everyone is exposed. Its UV component is the major epidemiologic risk factor for squamous cell carcinoma of the skin. Of the multiple steps in tumor progression, those that are sunlight-related would be revealed if they contained mutations specific to UV. In a series of New England and Swedish patients, the authors find that 14/24 (58%) of invasive squamous cell carcinomas of the skin contain mutations in the p53 tumor suppressor gene, each altering the amino acid sequence. Involvement of UV light in these p53 mutations is indicated by the presence in three of the tumors of a CC {yields} TT double-base change, which is only known to be induced by UV. UV is also implicated by a UV-like occurrence of mutations exclusively at dipyrimidine sites, including a high frequency of C {yields} T substitutions. p53 mutations in internal malignancies do not show these UV-specific mutations. The dipyrimidine specificity also implicates dipyrimidine photoproducts containing cytosine as oncogenic photoproducts. They believe these results identify a carcinogen-related step in a gene involved in the subsequent human cancer.

  12. Depletion of runt-related transcription factor 2 (RUNX2) enhances SAHA sensitivity of p53-mutated pancreatic cancer cells through the regulation of mutant p53 and TAp63

    PubMed Central

    Ogata, Takehiro; Nakamura, Mizuyo; Sang, Meijie; Yoda, Hiroyuki; Hiraoka, Kiriko; Yin, Danjing; Sang, Mexiang; Shimozato, Osamu

    2017-01-01

    Suberoylanilide hydroxamic acid (SAHA) represents one of the new class of anti-cancer drugs. However, multiple lines of clinical evidence indicate that SAHA might be sometimes ineffective on certain solid tumors including pancreatic cancer. In this study, we have found for the first time that RUNX2/mutant p53/TAp63-regulatory axis has a pivotal role in the determination of SAHA sensitivity of p53-mutated pancreatic cancer MiaPaCa-2 cells. According to our present results, MiaPaCa-2 cells responded poorly to SAHA. Forced depletion of mutant p53 stimulated SAHA-mediated cell death of MiaPaCa-2 cells, which was accomapanied by a further accumulation of γH2AX and cleaved PARP. Under these experimental conditions, pro-oncogenic RUNX2 was strongly down-regulated in mutant p53-depleted MiaPaCa-2 cells. Surprisingly, RUNX2 silencing augmented SAHA-dependent cell death of MiaPaCa-2 cells and caused a significant reduction of mutant p53. Consistent with these observations, overexpression of RUNX2 in MiaPaCa-2 cells restored SAHA-mediated decrease in cell viability and increased the amount of mutant p53. Thus, it is suggestive that there exists a positive auto-regulatory loop between RUNX2 and mutant p53, which might amplify their pro-oncogenic signals. Intriguingly, knockdown of mutant p53 or RUNX2 potentiated SAHA-induced up-regulation of TAp63. Indeed, SAHA-stimulated cell death of MiaPaCa-2 cells was partially attenuated by p63 depletion. Collectively, our present observations strongly suggest that RUNX2/mutant p53/TAp63-regulatory axis is one of the key determinants of SAHA sensitivity of p53-mutated pancreatic cancer cells. PMID:28671946

  13. Depletion of runt-related transcription factor 2 (RUNX2) enhances SAHA sensitivity of p53-mutated pancreatic cancer cells through the regulation of mutant p53 and TAp63.

    PubMed

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

    2017-01-01

    Suberoylanilide hydroxamic acid (SAHA) represents one of the new class of anti-cancer drugs. However, multiple lines of clinical evidence indicate that SAHA might be sometimes ineffective on certain solid tumors including pancreatic cancer. In this study, we have found for the first time that RUNX2/mutant p53/TAp63-regulatory axis has a pivotal role in the determination of SAHA sensitivity of p53-mutated pancreatic cancer MiaPaCa-2 cells. According to our present results, MiaPaCa-2 cells responded poorly to SAHA. Forced depletion of mutant p53 stimulated SAHA-mediated cell death of MiaPaCa-2 cells, which was accomapanied by a further accumulation of γH2AX and cleaved PARP. Under these experimental conditions, pro-oncogenic RUNX2 was strongly down-regulated in mutant p53-depleted MiaPaCa-2 cells. Surprisingly, RUNX2 silencing augmented SAHA-dependent cell death of MiaPaCa-2 cells and caused a significant reduction of mutant p53. Consistent with these observations, overexpression of RUNX2 in MiaPaCa-2 cells restored SAHA-mediated decrease in cell viability and increased the amount of mutant p53. Thus, it is suggestive that there exists a positive auto-regulatory loop between RUNX2 and mutant p53, which might amplify their pro-oncogenic signals. Intriguingly, knockdown of mutant p53 or RUNX2 potentiated SAHA-induced up-regulation of TAp63. Indeed, SAHA-stimulated cell death of MiaPaCa-2 cells was partially attenuated by p63 depletion. Collectively, our present observations strongly suggest that RUNX2/mutant p53/TAp63-regulatory axis is one of the key determinants of SAHA sensitivity of p53-mutated pancreatic cancer cells.

  14. DN-R175H p53 mutation is more effective than p53 interference in inducing epithelial disorganization and activation of proliferation signals in human carcinoma cells: role of E-cadherin.

    PubMed

    Rieber, Manuel; Strasberg Rieber, Mary

    2009-10-01

    One of the hallmarks of carcinomas is epithelial disorganization, linked to overexpression of matrix metalloproteases (MMP) like MMP-9, loss of intercellular E-cadherin and activation of epidermal growth receptor (EGFR/erbB1). Since the p53 tumor suppressor pathway is inactivated in most human cancers due to gene mutations or defective wt p53 signaling, we now investigated in human wt p53 breast carcinoma MCF-7 cells, whether single treatment with the p53 transactivation pharmacological inhibitor pifithrin-alpha, transient p53 siRNA interference or stable insertion of a dominant-negative (DN) R175H p53 mutant increase: (i) EGFR/erbB1 activation, (ii) MMP-9 expression and (iii) loss of surface E-cadherin. Transient abrogation of wt p53 function increased phosphorylation of EGFR/erbB1 and MMP-9 expression. However, all these effects were much more pronounced in cells stably transduced with the dominant negative-Arg-175His mutant p53 (DN-R175H mutant p53), which also showed loss of epithelial cytoarchitecture and extensive E-cadherin downregulation. Collectively, these results support the notion that the DN-R175H mutant p53 exerts a gain of oncogenic function by promoting disruption of E-cadherin intercellular contacts and activation of proliferation signals. Our data suggests that epithelial shape and growth control are unequally affected depending on how wt p53 function is impaired and whether partial or full tumor suppressor activity is lost.

  15. EGFR, p53, IDH-1 and MDM2 immunohistochemical analysis in glioblastoma: therapeutic and prognostic correlation.

    PubMed

    Montgomery, Richard Murdoch; Queiroz, Luciano de Souza; Rogerio, Fabio

    2015-07-01

    We studied 36 glioblastoma cases at HC-UNICAMP from 2008 to 2012 and classified the immunohistochemical distribution of the wild-type epidermal growth factor receptor (EGFR), mutated forms of p53 protein and isocitrate dehydrogenase-1 (IDH-1) and murine double protein 2 (MDM2). Immunostaining findings were correlated with clinical data and response to treatment (surgery, chemotherapy and radiotherapy). About 97% of the tumors were primary, most of them localized in the frontal lobe. Mean time free of clinical or symptomatic disease and free time of radiological disease were 7.56 and 7.14 months, respectively. We observed a significant positive correlation between expressions of p53 and MDM2, EGFR and MDM2. Clinical, radiological and overall survivals also showed a significant positive correlation. p53 staining and clinical survival showed a significant negative correlation. The current series provides clinical and histopathological data that contribute to knowledge on glioblastoma in Brazilians.

  16. Modulation of the Disordered Conformational Ensembles of the p53 Transactivation Domain by Cancer-Associated Mutations

    PubMed Central

    Ganguly, Debabani; Chen, Jianhan

    2015-01-01

    Intrinsically disordered proteins (IDPs) are frequently associated with human diseases such as cancers, and about one-fourth of disease-associated missense mutations have been mapped into predicted disordered regions. Understanding how these mutations affect the structure-function relationship of IDPs is a formidable task that requires detailed characterization of the disordered conformational ensembles. Implicit solvent coupled with enhanced sampling has been proposed to provide a balance between accuracy and efficiency necessary for systematic and comparative assessments of the effects of mutations as well as post-translational modifications on IDP structure and interaction. Here, we utilize a recently developed replica exchange with guided annealing enhanced sampling technique to calculate well-converged atomistic conformational ensembles of the intrinsically disordered transactivation domain (TAD) of tumor suppressor p53 and several cancer-associated mutants in implicit solvent. The simulations are critically assessed by quantitative comparisons with several types of experimental data that provide structural information on both secondary and tertiary levels. The results show that the calculated ensembles reproduce local structural features of wild-type p53-TAD and the effects of K24N mutation quantitatively. On the tertiary level, the simulated ensembles are overly compact, even though they appear to recapitulate the overall features of transient long-range contacts qualitatively. A key finding is that, while p53-TAD and its cancer mutants sample a similar set of conformational states, cancer mutants could introduce both local and long-range structural modulations to potentially perturb the balance of p53 binding to various regulatory proteins and further alter how this balance is regulated by multisite phosphorylation of p53-TAD. The current study clearly demonstrates the promise of atomistic simulations for detailed characterization of IDP conformations, and

  17. Modulation of the disordered conformational ensembles of the p53 transactivation domain by cancer-associated mutations.

    PubMed

    Ganguly, Debabani; Chen, Jianhan

    2015-04-01

    Intrinsically disordered proteins (IDPs) are frequently associated with human diseases such as cancers, and about one-fourth of disease-associated missense mutations have been mapped into predicted disordered regions. Understanding how these mutations affect the structure-function relationship of IDPs is a formidable task that requires detailed characterization of the disordered conformational ensembles. Implicit solvent coupled with enhanced sampling has been proposed to provide a balance between accuracy and efficiency necessary for systematic and comparative assessments of the effects of mutations as well as post-translational modifications on IDP structure and interaction. Here, we utilize a recently developed replica exchange with guided annealing enhanced sampling technique to calculate well-converged atomistic conformational ensembles of the intrinsically disordered transactivation domain (TAD) of tumor suppressor p53 and several cancer-associated mutants in implicit solvent. The simulations are critically assessed by quantitative comparisons with several types of experimental data that provide structural information on both secondary and tertiary levels. The results show that the calculated ensembles reproduce local structural features of wild-type p53-TAD and the effects of K24N mutation quantitatively. On the tertiary level, the simulated ensembles are overly compact, even though they appear to recapitulate the overall features of transient long-range contacts qualitatively. A key finding is that, while p53-TAD and its cancer mutants sample a similar set of conformational states, cancer mutants could introduce both local and long-range structural modulations to potentially perturb the balance of p53 binding to various regulatory proteins and further alter how this balance is regulated by multisite phosphorylation of p53-TAD. The current study clearly demonstrates the promise of atomistic simulations for detailed characterization of IDP conformations, and

  18. p53 codon 72 polymorphism and breast cancer risk: A meta-analysis

    PubMed Central

    HOU, JING; JIANG, YUAN; TANG, WENRU; JIA, SHUTING

    2013-01-01

    p53 is a tumor suppressor gene and plays important roles in the etiology of breast cancer. Studies have produced conflicting results concerning the role of p53 codon 72 polymorphism (G>C) on the risk of breast cancer; therefore, a meta-analysis was performed to estimate the association between the p53 codon 72 polymorphism and breast cancer. Screening of the PubMed database was conducted to identify relevant studies. Studies containing available genotype frequencies of the p53 codon 72 polymorphism were selected and a pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. Sixty-one published studies, including 28,539 breast cancer patients and 32,788 controls were identified. The results suggest that variant genotypes are not associated with breast cancer risk (Pro/Pro + Arg/Pro vs. Arg/Arg: OR=1.016, 95% CI=0.931–1.11, P=0.722). The symmetric funnel plot, Egger’s test (P=0.506) and Begg’s test (P=0.921) were all suggestive of the lack of publication bias. This meta-analysis suggests that the p53 codon 72 Pro/Pro + Arg/Pro genotypes are not associated with an increased risk of breast cancer. To validate the association between the p53 codon 72 polymorphism and breast cancer, further studies with larger numbers of participants worldwide are required. PMID:23737888

  19. Tumour suppressor gene p53 mutation in a case of haemangiosarcoma of a dog.

    PubMed

    Mayr, B; Zwetkoff, S; Schaffner, G; Reifinger, M

    2002-01-01

    Haemangiosarcomas of dogs were analysed by molecular genetic techniques. Regions of the tumour suppressor gene p53, including the well-known tumour hot spots (codons 175, 245, 248, 249, 273 and 282) were screened. A 24 bp deletion was detected in exon 5 of the gene.

  20. Label-free Detection of Missense Mutations and Methylation Differences in the p53 Gene Using Optically Diffracting Hydrogels

    PubMed Central

    MacConaghy, Kelsey I.; Chadly, Duncan M.; Stoykovich, Mark P.; Kaar, Joel L.

    2015-01-01

    We have developed a novel approach for DNA detection as well as genetic screening of mutations by uniquely combining DNA-responsive and optically diffracting materials. This approach entails the polymerization of a photonic crystal within a hydrogel network that alters the diffraction of light in response to a target DNA strand. The utility of this approach, which permits label-free sensing, was demonstrated via the detection of a target sequence from the DNA binding domain of the major tumor suppressor protein p53. Using a complementary capture probe strand, we were able to detect down to picomole concentrations of the target p53 sequence. Moreover, we demonstrated that this approach could readily detect a single base pair mutation in the target strand, which corresponds to the hotspot cancer mutation R175H in p53. The sensitivity of detection was increased by lowering the rate of annealing of the target strand and adjusting the solution ionic strength during optical characterization. Changes in ionic strength during characterization impact the melting temperature of the bound target DNA and the Donnan potential between the hydrogel and solution, which influence detection. We further showed that this approach is sensitive to epigenetic changes via the detection of a fully methylated form of the target p53 sequence. Ultimately, this approach represents a new paradigm for DNA detection and specifically genetic screening of p53 as well as other disease markers and nucleotide modifications that alter the properties of DNA (e.g., epigenetic alterations and adducts with chemical carcinogens). PMID:26270146

  1. The Enigma of p53.

    PubMed

    Lozano, Guillermina

    2016-12-08

    This perspective will focus on the physiological impact of wild-type and mutant p53 activities. In particular, the tissue-specific nature of activation of p53 targets and their subsequent effects on cell behavior will be discussed. Because mutations in p53 are common in human cancers, the regulation and physiological consequences of mutant p53 proteins will also be discussed.

  2. 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.

  3. P53 mutation in acute T cell lymphoblastic leukemia is of somatic origin and is stable during establishment of T cell acute lymphoblastic leukemia cell lines.

    PubMed Central

    Yeargin, J; Cheng, J; Yu, A L; Gjerset, R; Bogart, M; Haas, M

    1993-01-01

    Samples donated by patients with T cell acute lymphoblastic leukemia (T-ALL) were screened for mutations of the p53 tumor suppressor gene. Peripheral blood cells of T-ALL relapse patient H.A. were found to possess a heterozygous point mutation at codon 175 of the p53 gene. To determine whether this was an inherited mutation, a B cell line (HABL) was established. Leukemic T cell lines (HATL) were concurrently established by growing peripheral blood leukemic T cells at low oxygen tension in medium supplemented with IGF-I. Previously we had shown that > 60% of leukemic T cell lines possessed mutations in the p53 gene (Cheng, J., and M. Hass. 1990. Mol. Cell. Biol. 10:5502), mutations that might have originated with the donor's leukemic cells, or might have been induced during establishment of the cell lines. To answer whether establishment of the HATL lines was associated with the induction of p53 mutations, cDNAs of the HATL and HABL lines were sequenced. The HATL lines retained the same heterozygous p53 mutation that was present in the patient's leukemic cells. The HABL line lacked p53 mutations. Immunoprecipitation with specific anti-p53 antibodies showed that HATL cells produced p53 proteins of mutant and wild type immunophenotype, while the HABL line synthesized only wild-type p53 protein. The HATL cells had an abnormal karyotype, while the HABL cells possessed a normal diploid karyotype. These experiments suggest that (a) p53 mutation occurred in the leukemic cells of relapse T-ALL patient HA; (b) the mutation was of somatic rather than hereditary origin; (c) the mutation was leukemia associated; and (d) establishment of human leukemia cell lines needs not be associated with in vitro induction of p53 mutations. It may be significant that patient HA belonged to a category of relapse T-ALL patients in whom a second remission could not be induced. Images PMID:8486778

  4. Role of wild-type p53 in apoptotic and non-apoptotic cell death induced by X-irradiation and heat treatment in p53-mutated mouse M10 cells.

    PubMed

    Ito, Atsushi; Nakano, Hisako; Shinohara, Kunio

    2010-01-01

    The sensitizing effects of wild-type p53 on X-ray-induced cell death and on heat-induced apoptosis in M10, a radiosensitive and Trp53 (mouse p53 gene)-mutated lymphoma cell line which dies through necrosis by X-irradiation, were investigated using three M10 derived transfectants with wild-type TP53 (human p53 gene). Cell death was determined by colony formation and/or dye exclusion test, and apoptosis was detected as the changes in nuclear morphology by Giemsa staining. Expression of wild-type p53 protein increased radiosensitivity of cell death as determined by both clonogenic and dye exclusion assays. This increase in radiosensitivity was attributable largely to apoptosis induction in addition to a small enhancement of necrosis. Interestingly neither pathway to cell death was accompanied by caspase-3 activation. On the other hand, heat-induced caspase-3 dependent apoptotic cell death without transfection was further increased by the transfection of wild-type p53. In conclusion, the introduction of wild-type p53 enhanced apoptotic cell death by X-rays or heat via different mechanisms that do or do not activate caspase-3, respectively. In addition, p53 also enhanced the X-ray-induced necrosis in M10 cells.

  5. Targeting of MCL-1 kills MYC-driven mouse and human lymphomas even when they bear mutations in p53.

    PubMed

    Kelly, Gemma L; Grabow, Stephanie; Glaser, Stefan P; Fitzsimmons, Leah; Aubrey, Brandon J; Okamoto, Toru; Valente, Liz J; Robati, Mikara; Tai, Lin; Fairlie, W Douglas; Lee, Erinna F; Lindstrom, Mikael S; Wiman, Klas G; Huang, David C S; Bouillet, Philippe; Rowe, Martin; Rickinson, Alan B; Herold, Marco J; Strasser, Andreas

    2014-01-01

    The transcriptional regulator c-MYC is abnormally overexpressed in many human cancers. Evasion from apoptosis is critical for cancer development, particularly c-MYC-driven cancers. We explored which anti-apoptotic BCL-2 family member (expressed under endogenous regulation) is essential to sustain c-MYC-driven lymphoma growth to reveal which should be targeted for cancer therapy. Remarkably, inducible Cre-mediated deletion of even a single Mcl-1 allele substantially impaired the growth of c-MYC-driven mouse lymphomas. Mutations in p53 could diminish but not obviate the dependency of c-MYC-driven mouse lymphomas on MCL-1. Importantly, targeting of MCL-1 killed c-MYC-driven human Burkitt lymphoma cells, even those bearing mutations in p53. Given that loss of one allele of Mcl-1 is well tolerated in healthy tissues, our results suggest that therapeutic targeting of MCL-1 would be an attractive therapeutic strategy for MYC-driven cancers.

  6. [Abnormal expression of c-myc, p53, p16 protein and GNAS1 gene mutation in fibrous dysplasia].

    PubMed

    Tang, Juan; Zhao, Hong-ye; Zheng, Li; Zhang, Hui-zhen; Jiang, Zhi-ming

    2009-05-01

    To study the significance of c-myc, p53 and p16 protein expression in fibrous dysplasia, to detect the GNAS1 gene mutation in fibrous dysplasia, and to explore the property of fibrous dysplasia. The expression of c-myc, p53 and p16 protein was evaluated by immunohistochemistry SP method in 35 cases of fibrous dysplasia including 1 FD with malignancy, 1 Mazabraud syndrome and 20 control cases (10 cases of bony callus, 10 cases of osteosarcoma). Genomic DNA extraction, PCR amplification and gene sequencing were used to detect GNAS1 gene mutation in 35 cases of fibrous dysplasia. C-myc protein immunoreactivity was detected in 91 percentage of FD (P = 0.001). Compared with the negative control group, the difference was significant. P16 positive was detected in 34 FD cases (P = 0.001). The difference was significant as compared with the positive control group. Positive p53 protein expression was detected in the only 1 case of fibrous dysplasia with malignant transformation. PCR amplification was successful in 12 of 35 FD cases. Two of the 12 FD cases were detected to have GNAS1 gene mutation, in which 1 case was FD of Mazabraud syndrome, 1 case was a monostotic lesion. C-myc could be another protooncogene in addition to c-fos in the fibrous dysplasia disease. P53 protein overexpression could be useful in the diagnosis of FD malignancy and in the prediction of the prognosis of FD. The abnormal expression of the gene p16 might play an important role in the formation of FD. The GNAS1 mutation exist in FD. All of the results indicate that FD could be a neoplasia disease, caused by multiple factors leading to a dysfunction of bone development.

  7. p53 missense but not truncation mutations are associated with low levels of p21CIP1/WAF1 mRNA expression in primary human sarcomas

    PubMed Central

    Mousses, S; Gokgoz, N; Wunder, J S; Ozcelik, H; Bull, S; Bell, R S; Andrulis, I L

    2001-01-01

    Many growth-suppressing signals converge to control the levels of the CDK inhibitor p21CIP1/WAF1. Some human cancers exhibit low levels of expression of p21CIP1/WAF1and mutations in p53 have been implicated in this down-regulation. To evaluate whether the presence of p53 mutations was related to the in vivo expression of p21CIP1/WAF1 mRNA in sarcomas we measured the p21CIP1/WAF1 mRNA levels for a group of 71 primary bone and soft tissue tumours with known p53 status. As expected, most tumours with p53 mutations expressed low levels of p21CIP1/WAF1 mRNA. However, we identified a group of tumours with p53 gene mutations that exhibited normal or higher levels of p21CIP1/WAF1 mRNA. The p53 mutations in the latter group were not the common missense mutations in exons 4–9, but were predominantly nonsense mutations predicted to result in truncation of the p53 protein. The results of this study suggest that different types of p53 mutations can have different effects on the expression of downstream genes such as p21CIP1/WAF1 in human sarcomas. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11401317

  8. d-Amino acid mutation of PMI as potent dual peptide inhibitors of p53-MDM2/MDMX interactions.

    PubMed

    Li, Xiang; Liu, Chao; Chen, Si; Hu, Honggang; Su, Jiacan; Zou, Yan

    2017-09-07

    According to the previously reported potent dual l-peptide PMI of p53-MDM2/MDMX interactions, a series of d-amino acid mutational PMI analogues, PMI-1-4, with enhanced proteolytic resistence and in vitro tumor cell inhibitory activities were reported, of which Liposome-PMI-1 showed a stronger inhibitory activity against the U87 cell lines than Nutlin-3. This d-amino acid mutation strategy may give a hand for enhancing the potential of peptide drugs. Copyright © 2017. Published by Elsevier Ltd.

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

    DTIC Science & Technology

    2006-06-01

    E., Belew, R. K., and Olson, A. J. (1998). Automated docking using a lamarckian genetic algorithm and emperical binding free energy function. J...Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT: Of the genetic alterations associated with breast cancer, changes in p53 are the most...8 References…………………………………………………………………………….8 MARMORSTEIN, Ronen (5) INTRODUCTION Of the genetic alterations

  10. Identification and characterization of small molecules that inhibit nonsense-mediated RNA decay and suppress nonsense p53 mutations.

    PubMed

    Martin, Leenus; Grigoryan, Arsen; Wang, Ding; Wang, Jinhua; Breda, Laura; Rivella, Stefano; Cardozo, Timothy; Gardner, Lawrence B

    2014-06-01

    Many of the gene mutations found in genetic disorders, including cancer, result in premature termination codons (PTC) and the rapid degradation of their mRNAs by nonsense-mediated RNA decay (NMD). We used virtual library screening, targeting a pocket in the SMG7 protein, a key component of the NMD mechanism, to identify compounds that disrupt the SMG7-UPF1 complex and inhibit NMD. Several of these compounds upregulated NMD-targeted mRNAs at nanomolar concentrations, with minimal toxicity in cell-based assays. As expected, pharmacologic NMD inhibition disrupted SMG7-UPF1 interactions. When used in cells with PTC-mutated p53, pharmacologic NMD inhibition combined with a PTC "read-through" drug led to restoration of full-length p53 protein, upregulation of p53 downstream transcripts, and cell death. These studies serve as proof-of-concept that pharmacologic NMD inhibitors can restore mRNA integrity in the presence of PTC and can be used as part of a strategy to restore full-length protein in a variety of genetic diseases.

  11. Effect of Mutation on an Aggregation-Prone Segment of p53: From Monomer to Dimer to Multimer.

    PubMed

    Das, Atanu; Makarov, Dmitrii E

    2016-11-17

    Protein aggregation and amyloid formation are implicated in many diseases as well as in other biological phenomena. Recent studies have suggested that amyloid formation of tumor suppressor p53 can lead to loss of its physiological function, resulting in accelerated cancer progression. Design of cancer therapeutics, therefore, requires understanding of the mechanism of p53 aggregation. Here, we have employed atomistic simulations to characterize the aggregation process of the aggregation-prone (as suggested by experimental studies) p53 fragment (LTIITLE, 252-258) and to assess the efficiency of its I254R mutant as an aggregation suppressor. We show that the wild-type sequence attains stable β-sheet rich structure in the parallely arranged dimeric form, which dissociates in a sequential manner under mechanical force. The wild-type sequence further displays high aggregation propensity self-assembling into structures with parallel peptide arrangement. The I254R mutation destabilizes the dimer, changes the mechanical dissociation of the dimer to cooperative unfolding, reduces the aggregation propensity of the sequence, and alters the relative orientation of the peptides in the aggregate. Addition of the wild-type sequence, however, partially restores the aggregation propensity of the I254R mutant.

  12. P53 codon 72 Arg/Pro polymorphism and glioma risk: an updated meta-analysis.

    PubMed

    He, Fang; Xia, Yi; Liu, Huafeng; Li, Jin; Wang, Chao

    2013-10-01

    P53 codon 72 Arg/Pro is a C/G variation upstream of the p53 gene on human chromosome 17p13. Many case-control studies have investigated the association between p53 codon 72 Arg/Pro polymorphism and glioma risk but provided inconsistent findings. To better understand the pathogenesis of glioma, we performed the current meta-analysis by pooling data from all available individual studies. According to the inclusion criteria, ten independent publications with 11 case-control studies were included into this meta-analysis. The pooled odds ratio (OR) with 95 % confidence interval (95 % CI) was calculated to estimate the effect of p53 codon 72 Arg/Pro variant on the development of glioma. Overall, no appreciable correlation was observed among the total studies in all gene models (ORPro allele vs. Arg allele = 1.04, 95 % CI = 0.90-1.20, P OR = 0.581; ORPro/Pro vs. Arg/Arg = 0.95, 95 % CI = 0.80-1.14, P OR = 0.614; ORPro/Arg vs. Arg/Arg = 1.01, 95 % CI = 0.79-1.29, P OR = 0.993; ORPro/Arg + Pro/Pro vs. Arg/Arg = 1.03, 95 % CI = 0.82-1.29, P OR = 0.799; ORPro/Pro vs. Arg/Arg + Pro/Arg = 1.02, 95 % CI = 0.86-1.22, P OR = 0.785). In stratified analyses by ethnicity, source of controls, and glioma subtypes, the p53 codon 72 Arg/Pro polymorphism did not alter the risk for glioma in population-based, hospital-based, astrocytoma, and oligodendroglioma studies among Caucasian. Interestingly, the Pro/Pro genotype seemed to be negatively associated with the glioma risk among patients with glioblastoma (ORPro/Pro vs. Arg/Arg = 0.68, 95 % CI = 0.48-0.95, P OR = 0.026). Our study suggests that the polymorphism of p53 codon 72 Arg/Pro may play a protective role in the development of glioblastoma. The relationship of p53 codon 72 Arg/Pro polymorphism with the susceptibility to glioma needs further estimation by more individual studies with high quality across ethnicities.

  13. 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…

  14. 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…

  15. Specific-mutational patterns of p53 gene in bladder transitional cell carcinoma among a group of Iraqi patients exposed to war environmental hazards

    PubMed Central

    2012-01-01

    Background To unfold specific-mutational patterns in TP53 gene due to exposures to war environmental hazards and to detect the association of TP53 gene alteration with the depth of bladder cancer. Methods Twenty-nine bladder carcinomas were analyzed for TP53 alterations. PCR-single strand conformational polymorphism analysis, DNA sequencing and immunohistochemical analysis using monoclonal mouse anti-human p53 antibody (Clone DO-7) were employed. Results TP53 gene mutations occurred in 37.9% of the cases while TP53 overexpression occurred in 58.6%. Both of them were associated with deep invasive-tumors. Single mutations were seen in 63.6%, whereas only 27.3% have shown double mutations. Four mutations were frameshifted (30.8%); two of them showed insertion A after codon 244. There was no significant association between TP53 mutations and protein overexpression (P>0.05), while a significant association was observed between TP53 alterations and tumors progression (P ≤ 0.01). Conclusion The infrequent TP53mutations, especially insertion A and 196 hotspot codon, may represent the specific-mutational patterns in bladder carcinoma among the Iraqi patients who were exposed to war environmental hazards. TP53 alteration associated with bladder cancer progression should be analyzed by both mutational and protein expression analysis. PMID:22929185

  16. Specific-mutational patterns of p53 gene in bladder transitional cell carcinoma among a group of Iraqi patients exposed to war environmental hazards.

    PubMed

    Al-Kashwan, Thekra A; Houshmand, Massoud; Al-Janabi, Asaad; Melconian, Alice K; Al-Abbasi, Dhafir; Al-Musawi, Muhammad N; Rostami, Maryam; Yasseen, Akeel A

    2012-08-28

    To unfold specific-mutational patterns in TP53 gene due to exposures to war environmental hazards and to detect the association of TP53 gene alteration with the depth of bladder cancer. Twenty-nine bladder carcinomas were analyzed for TP53 alterations. PCR-single strand conformational polymorphism analysis, DNA sequencing and immunohistochemical analysis using monoclonal mouse anti-human p53 antibody (Clone DO-7) were employed. TP53 gene mutations occurred in 37.9% of the cases while TP53 overexpression occurred in 58.6%. Both of them were associated with deep invasive-tumors. Single mutations were seen in 63.6%, whereas only 27.3% have shown double mutations. Four mutations were frameshifted (30.8%); two of them showed insertion A after codon 244. There was no significant association between TP53 mutations and protein overexpression (P>0.05), while a significant association was observed between TP53 alterations and tumors progression (P ≤ 0.01). The infrequent TP53mutations, especially insertion A and 196 hotspot codon, may represent the specific-mutational patterns in bladder carcinoma among the Iraqi patients who were exposed to war environmental hazards. TP53 alteration associated with bladder cancer progression should be analyzed by both mutational and protein expression analysis.

  17. Mutations of C-reactive protein (CRP) -286 SNP, APC and p53 in colorectal cancer: implication for a CRP-Wnt crosstalk.

    PubMed

    Su, Hai-Xiang; Zhou, Hai-Hong; Wang, Ming-Yu; Cheng, Jin; Zhang, Shi-Chao; Hui, Feng; Chen, Xue-Zhong; Liu, Shan-Hui; Liu, Qin-Jiang; Zhu, Zi-Jiang; Hu, Qing-Rong; Wu, Yi; Ji, Shang-Rong

    2014-01-01

    C-reactive protein (CRP) is an established marker of inflammation with pattern-recognition receptor-like activities. Despite the close association of the serum level of CRP with the risk and prognosis of several types of cancer, it remains elusive whether CRP contributes directly to tumorigenesis or just represents a bystander marker. We have recently identified recurrent mutations at the SNP position -286 (rs3091244) in the promoter of CRP gene in several tumor types, instead suggesting that locally produced CRP is a potential driver of tumorigenesis. However, it is unknown whether the -286 site is the sole SNP position of CRP gene targeted for mutation and whether there is any association between CRP SNP mutations and other frequently mutated genes in tumors. Herein, we have examined the genotypes of three common CRP non-coding SNPs (rs7553007, rs1205, rs3093077) in tumor/normal sample pairs of 5 cancer types (n = 141). No recurrent somatic mutations are found at these SNP positions, indicating that the -286 SNP mutations are preferentially selected during the development of cancer. Further analysis reveals that the -286 SNP mutations of CRP tend to co-occur with mutated APC particularly in rectal cancer (p = 0.04; n = 67). By contrast, mutations of CRP and p53 or K-ras appear to be unrelated. There results thus underscore the functional importance of the -286 mutation of CRP in tumorigenesis and imply an interaction between CRP and Wnt signaling pathway.

  18. Wrapping Effects within a Proposed Function-Rescue Strategy for the Y220C Oncogenic Mutation of Protein p53

    PubMed Central

    Accordino, Sebastián R.; Rodríguez Fris, J. Ariel; Appignanesi, Gustavo A.

    2013-01-01

    Soluble proteins must protect their structural integrity from water attack by wrapping interactions which imply the clustering of nonpolar residues around the backbone hydrogen bonds. Thus, poorly wrapped hydrogen bonds constitute defects which have been identified as promoters of protein associations since they favor the removal of hydrating molecules. More specifically, a recent study of our group has shown that wrapping interactions allow the successful identification of protein binding hot spots. Additionally, we have also shown that drugs disruptive of protein-protein interfaces tend to mimic the wrapping behavior of the protein they replace. Within this context, in this work we study wrapping three body interactions related to the oncogenic Y220C mutation of the tumor suppressor protein p53. Our computational results rationalize the oncogenic nature of the Y220C mutation, explain the binding of a drug-like molecule already designed to restore the function of p53 and provide clues to help improve this function-rescue strategy and to apply in other drug design or re-engineering techniques. PMID:23365691

  19. The role of tumor protein 53 mutations in common human cancers and targeting the murine double minute 2-p53 interaction for cancer therapy.

    PubMed

    Hamzehloie, Tayebeh; Mojarrad, Majid; Hasanzadeh Nazarabadi, Mohammad; Shekouhi, Sahar

    2012-03-01

    The gene TP53 (also known as protein 53 or tumor protein 53), encoding transcription factor P53, is mutated or deleted in half of human cancers, demonstrating the crucial role of P53 in tumor suppression. There are reports of nearly 250 independent germ line TP53 mutations in over 100 publications. The P53 protein has the structure of a transcription factor and, is made up of several domains. The main function of P53 is to organize cell defense against cancerous transformation. P53 is a potent transcription factor that is activated in response to diverse stresses, leading to the induction of cell cycle arrest, apoptosis or senescence. The P53 tumor suppressor is negatively regulated in cells by the murine double minute 2 (MDM2) protein. Murine double minute 2 favors its nuclear export, and stimulates its degradation. Inhibitors of the P53-MDM2 interaction might be attractive new anticancer agents that could be used to activate wild-type P53 in tumors. Down regulation of MDM2 using an small interfering RNA (siRNA) approach has recently provided evidence for a new role of MDM2 in the P53 response, by modulating the inhibition of the cyclindependent kinase 2 (cdk2) by P21/WAF1 (also known as cyclin-dependent kinase inhibitor 1 or CDK-interacting protein 1).

  20. Dominant-negative but not gain-of-function effects of a p53.R270H mutation in mouse epithelium tissue after DNA damage.

    PubMed

    Wijnhoven, Susan W P; Speksnijder, Ewoud N; Liu, Xiaoling; Zwart, Edwin; vanOostrom, Conny Th M; Beems, Rudolf B; Hoogervorst, Esther M; Schaap, Mirjam M; Attardi, Laura D; Jacks, Tyler; van Steeg, Harry; Jonkers, Jos; de Vries, Annemieke

    2007-05-15

    p53 alterations in human tumors often involve missense mutations that may confer dominant-negative or gain-of-function properties. Dominant-negative effects result in inactivation of wild-type p53 protein in heterozygous mutant cells and as such in a p53 null phenotype. Gain-of-function effects can directly promote tumor development or metastasis through antiapoptotic mechanisms or transcriptional activation of (onco)genes. Here, we show, using conditional mouse technology, that epithelium-specific heterozygous expression of mutant p53 (i.e., the p53.R270H mutation that is equivalent to the human hotspot R273H) results in an increased incidence of spontaneous and UVB-induced skin tumors. Expression of p53.R270H exerted dominant-negative effects on latency, multiplicity, and progression status of UVB-induced but not spontaneous tumors. Surprisingly, gain-of-function properties of p53.R270H were not detected in skin epithelium. Apparently, dominant-negative and gain-of-function effects of mutant p53 are highly tissue specific and become most manifest upon stabilization of p53 after DNA damage.

  1. [Analysis of loss of heterozygosity of the tumor suppressor genes p53 and BRCA1 in ovarial carcinomas].

    PubMed

    Petrović, Bojana; Perović, Milica; Novaković, Ivana; Atanacković, Jasmina; Popović, Branka; Luković, Ljiljana; Petković, Spasoje

    2006-09-01

    Among the genes involved in ovarian carcinogenesis, there has been increased interest in tumor-suppressor genes p53 and BRCA1. Both of the genes make control of cell cycle, DNA repair and apoptosis. The p53 is a "genome guardian" inactivated in more than 50% of human cancers, while BRCA1 mutations are found mostly in breast and ovarian cancer. The aim of this investigation was to establish the frequency of loss of heterozygosity (LOH) in the regions of the genes p53 and BRCA1 in ovarian carcinomas, and to analyze the association of LOH with the disease stage and prognosis. We analyzed 20 patients with a confirmed diagnosis of epithelilal ovarian carcinoma. DNA for molecular-genetic analysis was extracted from the tumor tissue and blood as normal tissue of each person. Microsatellite markers of the regions of genes p53 and BRCA1 were amplified by PCR method. The determination of allelic status of microsatellites and detection of LOH was performed after PAA gel electroforesis. Both of the analyzed microsatellite markers were informative in 13/20 (65%) cases. In the region of gene p53, LOH was established in 4/13 (30.7%) tumors. One of them had histological gradus G1, one had gradus G2, and two of them had gradus G3, while all were with the International Federation of Gynecology and Obstetrics (FIGO) IIIc stage. In the region of gene BRCA1, LOH was detected in 5/13 (38.5%) tumors. Four of them had histological gradus G2, and one had gradus G3, while by the (FIGO) classification one was with stage Ib, one was with stage IIIb, while the three were with stage IlIc. LOH in both of the analyzed regions was detected in one tumor (7.70), with histological gradus G3 and the FIGO IIIc stage. The frequency of LOH in epthelial ovarian carcinomas was 30.7% and 38.5% for p53 and BRCA1 gene regions, respectively. Most of tumors with LOH had histological gradus G2 or G3, and the clinical FIGO stage IIIc, suggesting the association of this occurrence with a later phase of the disease.

  2. 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.

  3. Lack of association between p53 codon 72 polymorphism and endometrial cancer: a meta-analysis.

    PubMed

    Tang, Wenru; He, Xinggang; Chan, Ying; Luo, Ying

    2012-06-01

    It has been suggested that the p53 tumor suppressor gene Arg72Pro polymorphism is associated with endometrial cancer. However, results have been inconsistent. We performed this meta-analysis to estimate the association between p53 Arg72Pro polymorphism and endometrial cancer. An electronic search of PubMed was conducted to select studies. Studies containing available genotype frequencies of Arg72Pro were chosen, and the association was assessed by pooled odds ratios (ORs) with 95% confidence intervals (CIs). Nine published studies, including 829 endometrial cancer cases and 1387 controls, were identified. The overall results suggested that the variant genotypes were not associated with the endometrial cancer risk in all genetic models (additive model: OR 1.027, 95% CI 0.893-1.18, P=0.71; recessive model: OR 1.099, 95% CI 0.802-1.507, P=0.556; dominant model: OR 1.013, 95% CI 0.842-1.219 P=0.89). Similarly, the results were negative in subgroup analyses for ethnicity (Caucasian, Asian). This meta-analysis suggests that p53 codon 72 polymorphism is not associated with increased risk of endometrial cancer, especially in Caucasians and Asians. To validate the association between this polymorphism and endometrial cancer, further studies with larger numbers of participants worldwide are needed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. The patterns of p53 gene mutations differ inside and outside of exons 5-8 in breast and other cancers

    SciTech Connect

    Hartmann, A.; Blaszyk, H.; McGovern, R.M.

    1994-09-01

    Most studies of the p53 gene in tumors examine only exons 5-8. In these exons, there is a predominance of missense mutations clustered in four regions of high evolutionary conservation. We previously found 64 mutations in exons 5-8 of the p53 gene in 194 primary breast cancers. Herein, we report 18 additional mutations found by analyzing the promotor region, the first noncoding exon, and the remaining coding exons. Mutations were found in exons 4, 9, and 10, and flanking splice junctions, but not in the promotor region or in exons 1, 2, 3, and 11. Outside of exons 5-8 not a single missense mutation was found. Microdeletions and microinsertions predominate but nonsense and splice site mutations also occur. In contrast, the majority of mutations in exons 5-8 were missense changes which exclusively occurred at amino acids that were identical in all known p53 sequences which represent about 1.6 billion years of evolutionary divergence. The difference in the mutational pattern between these two regions of the p53 gene is due to a lack of missense and inframe microdeletion mutations outside exons 5-8 (p<.0001), whereas frameshift deletions and insertions, nonsense mutations and splicing defects are equally distributed over the gene. A review of the literature shows that the difference in the patterns of mutation inside and outside of exons 5-8 we have found in breast cancer is present in other types of cancers as well. These data show the importance of comparing equivalent exons when examining the pattern of p53 gene mutation in different populations. In addition, the paucity of missense mutations in breast and other cancers (even at amino acids identical throughout p53 gene evolution) indicates that at least some of the missense mutations in exons 2-4 and 9-11 result in a phenotype other than malignant transformation.

  5. Tumour selection advantage of non‐dominant negative P53 mutations in homozygotic MDM2‐SNP309 colorectal cancer cells

    PubMed Central

    Alazzouzi, Hafid; Suriano, Gianpaolo; Guerra, Angel; Plaja, Alberto; Espín, Eloi; Armengol, Manel; Alhopuro, Pia; Velho, Sergia; Shinomura, Yasuhisa; González‐Aguilera, Juan José; Yamamoto, Hiroyuki; Aaltonen, Lauri A; Moreno, Víctor; Capellà, Gabriel; Peinado, Miguel Angel; Seruca, Raquel; Arango, Diego

    2007-01-01

    Background Mdm2 is a natural inhibitor of p53 function and its overexpression impairs p53 transcriptional activity. T→G single‐nucleotide polymorphism at position 309 (SNP309) of mdm2 induces overexpression of mdm2, but inhibits p53. Objectives To determine whether SNP309 is a risk‐modifier polymorphism in colorectal cancer (CRC) and whether tumour selection of P53 mutations are influenced by SNP309. Methods Single‐stranded conformation polymorphism and automatic sequencing were performed. Results SNP309 is not associated with the risk of CRC or recurrence of tumours. These data do not over‐ride the tumour‐selection capabilities of P53 mutations in CRC. However, a significant association with non‐dominant‐negative P53 mutations (p = 0.02) was found. Conclusions MDM2‐SNP309 favours tumour selection of non‐dominant negative P53 mutations in CRC, which also show an earlier age of tumour onset. PMID:16825434

  6. Mutation R273H confers p53 a stimulating effect on the IGF-1R-AKT pathway via miR-30a suppression in breast cancer.

    PubMed

    Guo, Fangdong; Chen, Hongshen; Chang, Jian; Zhang, Lin

    2016-03-01

    p53 is the most highly mutated tumor suppressor in human malignancies. A wide array of p53 mutations has been revealed to play pivotal roles during cancer progression, which abolish anti-tumor functions of wild type p53 but also elicit tumorigenic effects by activating a diverse subset of downstream molecules. R273H mutation of p53 has been closely implicated in human cancer. Here we report miR-30a as a novel downstream target of p53 R273H mutant, which binds to the promoter region to repress miR-30a expression. Consequently, p53 R273H mutant enhances the migratory capabilities of tumor cells that are compromised by exogenous miR-30a over-expression. Our further investigation indicates that p53 R273H mutation unleashes the inhibition effect of miR-30a on IGF-1R expression, thus leading to elevated activation of IGF-1R-AKT signaling cascade in tumor cells.

  7. Frequent mutations of p53 gene in oesophageal squamous cell carcinomas with and without human papillomavirus (HPV) involvement suggest the dominant role of environmental carcinogens in oesophageal carcinogenesis.

    PubMed Central

    Chang, F.; Syrjänen, S.; Tervahauta, A.; Kurvinen, K.; Wang, L.; Syrjänen, K.

    1994-01-01

    Epidemiological evidence suggests that alcohol intake, use of tobacco, ingestion of mycotoxins and nitrosamines and nutritional deficiencies are high-risk factors for the development of oesophageal cancer. Similarly, viral infections have been postulated to play a role in some tumours. However, the molecular events underlying the development of oesophageal carcinoma are poorly understood as yet. Loss of p53 tumour-suppressor gene function has been found in different human malignancies, and it can occur in a variety of ways, including gene mutation and interaction with the E6 protein of oncogenic human papillomaviruses (HPVs). Because the oesophageal mucosa is potentially exposed to mutagens and HPVs, we studied DNA samples derived from nine HPV-positive squamous cell carcinomas and 12 HPV-negative tumours. Exons 5-9 of the p53 gene containing phylogenetically conserved domains were examined using the polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) technique. HPV detection was done using DNA in situ hybridisation with biotin-labelled HPV DNA probes. Mutations were detected in eight (38%) out of the 21 cases. Three mutations were found in exons 5/6, three in exon 7 and two in exon 8/9. Six (50%) of the 12 HPV-negative carcinomas showed p53 mutations. Two (22.2%) of the nine HPV-positive carcinomas were found to contain p53 mutations as well; one contained HPV 16 DNA sequences and showed p53 mutation in exon 8/9, and the other was HPV 6/11 positive with the mutation in exon 5/6. Although mutations were more common in HPV-negative tumours (50.0% vs 22.2%), the difference in p53 mutations in HPV-positive and -negative tumours did not reach statistical significance (P = 0.1946). These data indicate that inactivation of the p53 gene is a frequent event in oesophageal squamous cell carcinomas and such an inactivation might be an important molecular pathway for the development of oesophageal cancer. The findings of p53 mutations in HPV

  8. Analysis of Association Between MGMT and p53 Gene Single Nucleotide Polymorphisms and Laryngeal Cancer.

    PubMed

    Lv, Yayun; Jia, Chuanliang; Jiang, Aihua; Zhang, Hua; Wang, Yunqiang; Liu, Feifei; Yang, Linlin; Sun, Yan; Lv, Runli; Song, Xicheng

    2017-08-01

    To investigate the p53 and O(6)-methylguanine DNA methyltransferase (MGMT)5' upstream sequence gene promoter regions for single nucleotide polymorphisms and explore the p53 gene 5' upstream sequence consisting of two haplotypes to provide a genetic marker for the incidence of laryngeal squamous cell carcinoma. We included 96 cases of laryngeal squamous cell carcinoma and 102 controls. We used SNaPshot micro-sequencing analysis of the MGMT promoter region for four single nucleotide polymorphisms and p53 gene 5' upstream sequence loci (rs1625649, rs2287499, rs2287498, rs228749) genotypes. We calculated and compared two groups for genotypic and allelic frequencies, applied HaploView4.2 for computing rs2287499, rs2287498, rs228749 values and haplotype frequencies and tested control loci and Hardy-Weinberg equilibrium. All the experimental data were statistically evaluated using SPSS17.0. The Chi-square test was used for statistical analysis with p<0.05 indicating statistical significance. 5'Upstream single nucleotide polymorphisms rs1625649, rs2287499, rs2287498, rs228749 of p53 were polymorphic in both patient and control groups. There was no statistical significance in frequency distributions for the four loci genotypes when comparing patients and healthy controls (Chi-square values were 4.47, 0.98, 1.67, 4.68, respectively; p>0.05). However, allelic frequencies of the MGMT promoter region locus rs1625649 between patients and healthy control groups were statistically significantly different (chi-square value of 5.77; p<0.05). Differences between allelic frequencies for the p53 gene 5' upstream sequence loci rs2287499, rs2287498 and rs228749 between patients and the healthy control group were not statistically significant (Chi-square values were 1.11,1.56,3.36; p>0.05). Nor were those for the two haplotypes of rs2287499, rs2287498 and rs228749 between patients and the healthy control group were not statistically significant (Chi-square value 1.46, p>0.05). MGMT gene

  9. p53 mutation and cyclin D1 amplification correlate with cisplatin sensitivity in xenografted human squamous cell carcinomas from head and neck.

    PubMed

    Henriksson, Eva; Baldetorp, Bo; Borg, Ake; Kjellen, Elisabeth; Akervall, Jan; Wennerberg, Johan; Wahlberg, Peter

    2006-01-01

    To investigate the response of tumour growth to cisplatin treatment, in relation to p53 mutation and cyclin D1 dysregulation on DNA and protein level, biopsies from seven xenografted human squamous cell carcinomas from the head and neck were analysed with immunohistochemistry for p53 expression and cyclin D1 expression. Polymerase chain reaction-singlestranded conformation polymorphism was used to determine p53 mutations. Fluorescence in situ hybridization was performed to analyse cyclin D1 amplification. The mice were injected i.p. with NaCl (controls) or cisplatin. After injection the tumour volume were measured. The inhibition of tumour growth by cisplatin was defined as the area under the growth curves, and compared with the growth curves of the tumours in the control group. Xenografts with p53 mutation showed significantly higher resistance to cisplatin (p < 0.001) and also tumours with cyclin D1 amplification showed significantly higher resistance (p < 0.001).

  10. Assessment of the mutations of p53 suppressor gene and Ha- and Ki-ras oncogenes in malignant mesothelioma in relation to asbestos exposure: a study of 12 American patients.

    PubMed

    Kitamura, Fumihiko; Araki, Shunichi; Suzuki, Yasunosuke; Yokoyama, Kazuhito; Tanigawa, Takeshi; Iwasaki, Ryu

    2002-04-01

    In our previous study, we found no genetic alteration in exons 1 and 2 of Ha- and Ki-ras oncogenes nor in exons 5 to 9 of the p53 suppressor gene in seven Japanese malignant mesothelioma patients exposed to asbestos. To examine further whether malignant mesothelioma due to asbestos has genetic alterations in the p53 suppressor gene and in Ha- and Ki-ras oncogenes, we analyzed point mutations of these genes in paraffin embedded operative open biopsied samples of the primary tumor of malignant mesothelioma in twelve American patients. The genetic analysis was conducted by the PCR-SSCP (polymerase chain reaction single-strand conformation polymorphism) method in all patients and by sequencing analysis of DNA bases in the two patients with suspected gene mutation. The analysis of the p53 suppressor gene showed an amino acid converting mutation of exon 7 in one patient and a polymorphism of exon 6 in another patient; the former patient was a heavy smoker with a biphasic cell type. No genetic alteration was found in exons 1 and 2 of Ha- and Ki-ras oncogenes in any of the patients. The results suggest that the effects of asbestos on the p53 suppressor gene and Ha- and Ki-ras oncogenes in malignant mesothelioma are negligible. Further studies are needed to examine whether the observed mutation of the p53 suppressor gene is due to the combined effects of asbestos and smoking or to other unknown factors.

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

    PubMed Central

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

    2012-01-01

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

  12. Lipidomic analysis of skeletal muscle tissues of p53 knockout mice by nUPLC-ESI-MS/MS.

    PubMed

    Park, Se Mi; Byeon, Seul Kee; Lee, Hojun; Sung, Hyerim; Kim, Il Yong; Seong, Je Kyung; Moon, Myeong Hee

    2017-06-12

    Tumour suppressor p53 is known to be associated with the maintenance of mitochondrial functional properties in the skeletal muscles. As deactivation or mutation of p53 can affect the synthesis of lipids, investigating the relationship between p53-related energy generation metabolism and perturbation of lipid profile is critical. In this study, 329 lipid species (among 412 identified species) in two different skeletal muscle tissues (the gastrocnemius and soleus) from p53 knockout (KO) mice were quantitatively analysed using nanoflow ultrahigh performance liquid chromatography tandem mass spectrometry (nUPLC-MS/MS). Overall, lipids from the soleus tissues were more affected by p53 KO than those from the gastrocnemius in most lipid profiles. In p53 KO, lysophosphatidylcholine (LPC), lysophosphatidylserine (LPS), phosphatidic acid (PA), sphingomyelin (SM), and triacylglycerol (TAG), including 6 TAG (44:2, 46:0, 58:5, 58:8, 58:9, and 50:0), were significantly increased (p < 0.05) by 1.4-2-fold only in the soleus tissue. Overall monohexosylceramide (MHC) levels, including those of 3 MHC species (d18:0/24:0, d18:1/22:0, and d18:1/24:0), were significantly increased (p < 0.05) by 2-4 fold, only in the gastrocnemius tissue. The results suggest that lipid profiles are significantly altered by the lack of p53 in muscle tissues.

  13. Genetic basis for p53 overexpression in human breast cancer.

    PubMed Central

    Davidoff, A M; Humphrey, P A; Iglehart, J D; Marks, J R

    1991-01-01

    Overexpression of an activated form of the p53 protein may be involved in neoplastic transformation. We found widespread overexpression of p53 by immunohistochemical staining in 11 (22%) of 49 primary invasive human breast cancers. Northern blot analysis showed that this overexpression was not due to an increase in the steady-state level of p53 mRNA. The p53 gene was directly sequenced in 7 of these tumors with elevated levels of the protein and, in each case, a mutation that altered the coding sequence for p53 was found in a highly conserved region of the gene. Whereas 4 of these tumors contained only a mutant p53 allele, the other 3 tumors exhibited coding sequences from both a mutant and a wild-type allele. p53 mutations have previously been correlated with allelic loss of part of chromosome 17p that contains the p53 locus. Examination of all 49 breast tumors revealed a 61% frequency of deletion at or near the p53 locus. However, the presence of allelic deletion did not correlate with overexpression of the protein. Six tumors that were deleted but did not express high levels of the protein were sequenced and all retained a wild-type p53 allele. In this series of human breast cancers, overexpression of the p53 protein, not allelic loss on chromosome 17p, was always associated with mutation of the p53 gene. Images PMID:2052583

  14. p53 mutation is rare in oral mucosa brushings from patients previously treated for a head and neck squamous cell carcinoma.

    PubMed

    Acha-Sagredo, Amelia; Ruesga, Maria T; Rodriguez, Carlos; Aguirregaviria, Jose I; de Pancorbo, Marian M; Califano, Joseph A; Aguirre, Jose M

    2009-08-01

    Mutations of the tumour suppressor gene p53 are common in human cancer, and seem to be an early event in head and neck squamous cell carcinomas. The aim of our study was to determine the status of the tumour suppressor gene p53 in the oral mucosa of patients previously treated for a head and neck squamous cell carcinoma, at risk of developing an oral squamous cell carcinoma, but without oral clinical lesions. Oral brushings from 87 patients were sequenced with matched genomic DNA. No mutations were found in exons 5, 7 and 8, whereas in exon 6 silent mutations (n=6) and a polymorphism (n=7) were found. Mutation of the tumour suppressor gene p53 does not seem to be a frequent event in patients at risk but without oral lesions.

  15. Structural effects of the L145Q, V157F, and R282W cancer-associated mutations in the p53 DNA-binding core domain.

    PubMed

    Calhoun, Sara; Daggett, Valerie

    2011-06-14

    The p53 tumor suppressor is a transcription factor involved in many important signaling pathways, such as apoptosis and cell-cycle arrest. In over half of human cancers, p53 function is compromised by a mutation in its gene. Mutations in the p53 DNA-binding core domain destabilize the structure and reduce DNA-binding activity. We performed molecular dynamics simulations at physiological temperature to study the structural and dynamic effects of the L145Q, V157F, and R282W cancer-associated mutations in comparison to the wild-type protein. While there were common regions of destabilization in the mutant simulations, structural changes particular to individual mutations were also observed. Significant backbone deviations of the H2 helix and S7-S8 loop were observed in all mutant simulations; the H2 helix binds to DNA. In addition, the L145Q and V157F mutations, which are located in the β-sandwich core of the domain, disrupted the β-sheet structure and the loop-sheet-helix motif. The R282W mutation caused distortion of the loop-sheet-helix motif, but otherwise this mutant was similar to the wild-type structure. The introduction of these mutations caused rearrangement of the DNA-binding surface, consistent with their reduced DNA-binding activity. The simulations reveal detailed effects of the mutations on the stability and dynamics of p53 that may provide insight for therapeutic approaches.

  16. Prognostic significance of p53 immunohistochemical expression in adenoid cystic carcinoma of the salivary glands: a meta-analysis.

    PubMed

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

    2017-04-25

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

  17. Mutations of C-Reactive Protein (CRP) -286 SNP, APC and p53 in Colorectal Cancer: Implication for a CRP-Wnt Crosstalk

    PubMed Central

    Cheng, Jin; Zhang, Shi-Chao; Hui, Feng; Chen, Xue-Zhong; Liu, Shan-Hui; Liu, Qin-Jiang; Zhu, Zi-Jiang; Hu, Qing-Rong; Wu, Yi; Ji, Shang-Rong

    2014-01-01

    C-reactive protein (CRP) is an established marker of inflammation with pattern-recognition receptor-like activities. Despite the close association of the serum level of CRP with the risk and prognosis of several types of cancer, it remains elusive whether CRP contributes directly to tumorigenesis or just represents a bystander marker. We have recently identified recurrent mutations at the SNP position -286 (rs3091244) in the promoter of CRP gene in several tumor types, instead suggesting that locally produced CRP is a potential driver of tumorigenesis. However, it is unknown whether the -286 site is the sole SNP position of CRP gene targeted for mutation and whether there is any association between CRP SNP mutations and other frequently mutated genes in tumors. Herein, we have examined the genotypes of three common CRP non-coding SNPs (rs7553007, rs1205, rs3093077) in tumor/normal sample pairs of 5 cancer types (n = 141). No recurrent somatic mutations are found at these SNP positions, indicating that the -286 SNP mutations are preferentially selected during the development of cancer. Further analysis reveals that the -286 SNP mutations of CRP tend to co-occur with mutated APC particularly in rectal cancer (p = 0.04; n = 67). By contrast, mutations of CRP and p53 or K-ras appear to be unrelated. There results thus underscore the functional importance of the -286 mutation of CRP in tumorigenesis and imply an interaction between CRP and Wnt signaling pathway. PMID:25025473

  18. Systems-level analysis of the regulation and function of p53 dynamics in cancer

    NASA Astrophysics Data System (ADS)

    Batchelor, Eric

    Living cells use complex signaling pathways to detect environmental stimuli and generate appropriate responses. As methods for quantifying intracellular signaling have improved, several signaling pathways have been found to transmit information using signals that pulse in time. The transcription factor p53 is a key tumor suppressor and stress-response regulator that exhibits pulsatile dynamics. In response to DNA double-strand breaks, the concentration of p53 in the cell nucleus increases in pulses with a fixed amplitude, duration, and period; the mean number of pulses increases with DNA damage. p53 regulates the expression of over 100 target genes involved in a range of cellular stress responses including apoptosis, cell cycle arrest, and changes in metabolism. p53 pulsing directly impacts p53 function: altering p53 dynamics by pharmacologically inhibiting p53 degradation changes patterns of target gene expression and cell fate. While p53 pulsing serves an important signaling function, it is less clear what it accomplishes mechanistically. Here we will describe our recent efforts to determine the impact of p53 pulsing on the dynamics and coordination of target gene expression.

  19. Mutation of the endogenous p53 gene in cells transformed by HPV-16 E7 and EJ c-ras confers a growth advantage involving an autocrine mechanism.

    PubMed Central

    Peacock, J W; Benchimol, S

    1994-01-01

    Rat embryo fibroblasts transformed with the HPV-16 E7 gene and the activated c-H-ras gene fall into two distinct phenotypic classes. At high cell density, clones of one class form colonies in methylcellulose supplemented with low serum; at low cell density, these cells display responsiveness to mitogenic factors present in serum-free conditioned medium from rat embryo fibroblasts. In contrast, clones of the second class exhibit an absolute dependency on growth factors present in serum at all cell densities in the methylcellulose colony assay and fail to respond to conditioned medium. We find that the status of the endogenous p53 gene is tightly correlated with these two classes of clones. Clones of the first class contain missense mutations in the p53 gene and have lost the wild-type allele. Clones of the second class express wild-type p53 protein. The importance of mutant p53 expression in reducing the growth factor dependency of transformed clones was confirmed in a separate series of experiments in which rat embryo fibroblasts were transformed with three genes, E7 + ras + mutant p53. The growth behaviour of these triply transfected clones was similar to that of the E7 + ras clones expressing endogenous mutant p53. We demonstrate that the enhanced proliferation of E7 + ras clones expressing mutant p53 protein involves an autocrine mechanism. Images PMID:8131742

  20. 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.

  1. The biological impact of the human master regulator p53 can be altered by mutations that change the spectrum and expression of its target genes.

    PubMed

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

    2006-03-01

    Human tumor suppressor p53 is a sequence-specific master regulatory transcription factor that targets response elements (REs) in many genes. p53 missense mutations in the DNA-binding domain are often cancer associated. As shown with systems based on the yeast Saccharomyces cerevisiae, p53 mutants can alter the spectra and intensities of transactivation from individual REs. We address directly in human cells the relationship between changes in the p53 master regulatory network and biological outcomes. Expression of integrated, tightly regulated DNA-binding domain p53 mutants resulted in many patterns of apoptosis and survival following UV or ionizing radiation, or spontaneously. These patterns reflected changes in the spectra and activities of target genes, as demonstrated for P21, MDM2, BAX, and MSH2. Thus, as originally proposed for "master genes of diversity," p53 mutations in human cells can differentially influence target gene transactivation, resulting in a variety of biological consequences which, in turn, might be expected to influence tumor development and therapeutic efficacy.

  2. Analysis of p53 binding to DNA by fluorescence imaging microscopy.

    PubMed

    Ong, Hwee Jing; Siau, Jia Wei; Zhang, Jing Bo; Hong, Minghui; Flotow, Horst; Ghadessy, Farid

    2012-09-01

    Transcription factors play a central role in cell biology through binding to target DNA elements and regulating gene expression. In this study, we used the p53 tumour suppressor as a model transcription factor to develop an imaging based assay to measure DNA binding. The assay utilizes fluorescence imaging microscopy to detect labelled p53 bound to DNA coated on microbeads. We demonstrate the ability to multiplex the assay by interrogating simultaneous binding to variant DNA sequences present on tractable beads. Additionally, the assay measures activation of p53 for increased DNA binding by a known peptide in addition to reactivation of mutant p53 by a small molecule. It may therefore be adaptable to a high-content imaging screen for compounds capable of restoring the function of mutant p53 associated with cancer. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Frequent p53 mutation in brain (fetal)-type glycogen phosphorylase positive foci adjacent to human ‘de novo’olorectal carcinomas

    PubMed Central

    Shimada, S; Shiomori, K; Tashima, S; Tsuruta, J; Ogawa, M

    2001-01-01

    ‘de novo’ carcinogenesis has been advocated besides ‘adenoma carcinoma sequence’ as another dominant pathway leading to colorectal carcinoma. Our recent study has demonstrated that the distribution of brain (fetal)-type glycogen phosphorylase (BGP) positive foci (BGP foci) has a close relationship with the location of ‘de novo’ carcinoma. The aims of the present study are to investigate genetic alteration in the BGP foci and to characterize them in the ‘de novo’ carcinogenesis. 17 colorectal carcinomas without any adenoma component expressing both immunoreactive p53 and BGP protein were selected from 96 resected specimens from our previous study. Further investigations to examine the proliferating cell nuclear antigen (PCNA)-labelling index, and the p53 and the codon 12 of K-ras mutation using the polymerase chain reaction-single strand conformation polymorphism were performed in the BGP foci, BGP negative mucosa and carcinoma. The BGP foci were observed sporadically in the transitional mucosa adjacent to the carcinoma in all cases. The PCNA labelling index in the BGP foci was significantly higher than that in the BGP negative mucosa (P< 0.001). p53 mutations were observed in 8 carcinomas, but no K-ras mutation was detected. Interestingly, although none of the overexpressions of p53 protein was detected immunohistochemically in the BGP positive foci, the p53 gene frequently (41.2% of the BGP foci tested) mutated in spite of no K-ras mutation. The present study demonstrates potentially premalignant foci in the colorectal transitional mucosa with frequent p53 gene mutation. It is suggested that BGP foci are promising candidates for the further investigation of ‘de novo’ colorectal carcinogenesis. © 2001Cancer Research Campaign http://www.bjcancer.com PMID:11384100

  4. Phosphomimetic mutation of the N-terminal lid of MDM2 enhances the polyubiquitination of p53 through stimulation of E2-ubiquitin thioester hydrolysis.

    PubMed

    Fraser, Jennifer A; Worrall, Erin G; Lin, Yao; Landre, Vivien; Pettersson, Susanne; Blackburn, Elizabeth; Walkinshaw, Malcolm; Muller, Petr; Vojtesek, Borek; Ball, Kathryn; Hupp, Ted R

    2015-04-24

    Mouse double minute 2 (MDM2) has a phosphorylation site within a lid motif at Ser17 whose phosphomimetic mutation to Asp17 stimulates MDM2-mediated polyubiquitination of p53. MDM2 lid deletion, but not Asp17 mutation, induced a blue shift in the λ(max) of intrinsic fluorescence derived from residues in the central domain including Trp235, Trp303, Trp323, and Trp329. This indicates that the Asp17 mutation does not alter the conformation of MDM2 surrounding the tryptophan residues. In addition, Phe235 mutation enhanced MDM2 binding to p53 but did not stimulate its ubiquitination function, thus uncoupling increases in p53 binding from its E3 ubiquitin ligase function. However, the Asp17 mutation in MDM2 stimulated its discharge of the UBCH5a-ubiquitin thioester adduct (UBCH5a is a ubiquitin-conjugating enzyme E2D 1 UBC4/5 homolog yeast). This stimulation of ubiquitin discharge from E2 was independent of the p53 substrate. There are now four known effects of the Asp17 mutation on MDM2: (i) it alters the conformation of the isolated N-terminus as defined by NMR; (ii) it induces increased thermostability of the isolated N-terminal domain; (iii) it stimulates the allosteric interaction of MDM2 with the DNA-binding domain of p53; and (iv) it stimulates a novel protein-protein interaction with the E2-ubiquitin complex in the absence of substrate p53 that, in turn, increases hydrolysis of the E2-ubiquitin thioester bond. These data also suggest a new strategy to disrupt MDM2 function by targeting the E2-ubiquitin discharge reaction.

  5. 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

  6. Spontaneous and irradiation-induced tumor susceptibility in BRCA2 germline mutant mice and cooperative effects with a p53 germline mutation.

    PubMed

    McAllister, Kimberly A; Houle, Christopher D; Malphurs, Jason; Ward, Toni; Collins, N Keith; Gersch, William; Wharey, Laura; Seely, John C; Betz, Laura; Bennett, L Michelle; Wiseman, Roger W; Davis, Barbara J

    2006-01-01

    Mutations in both p53 and BRCA2 are commonly seen together in human tumors suggesting that the loss of both genes enhances tumor development. To elucidate this interaction in an animal model, mice lacking the carboxy terminal domain of Brca2 were crossed with p53 heterozygous mice. Females from this intercross were then irradiated with an acute dose of 5 Gy ionizing radiation at 5 weeks of age and compared to nonirradiated controls. We found decreased survival and timing of tumor onsets, and significantly higher overall tumor incidences and prevalence of particular tumors, including stomach tumors and squamous cell carcinomas, associated with the homozygous loss of Brca2, independent of p53 status. The addition of a p53 mutation had a further impact on overall survival, incidence of osteosarcomas and stomach tumors, and tumor latency. The spectrum of tumors observed for this Brca2 germline mouse model suggest that it faithfully recapitulates some human disease phenotypes associated with BRCA2 loss. In addition, these findings include extensive in vivo data demonstrating that germline Brca2 and p53 mutations cooperatively affect animal survivals, tumor susceptibilities, and tumor onsets.

  7. Molecular genetic characterization of p53 mutated oropharyngeal squamous cell carcinoma cells transformed with human papillomavirus E6 and E7 oncogenes.

    PubMed

    Oh, Ji-Eun; Kim, Jeong-Oh; Shin, Jung-Young; Zhang, Xiang-Hua; Won, Hye-Sung; Chun, Sang-Hoon; Jung, Chan-Kwon; Park, Won-Sang; Nam, Suk-Woo; Eun, Jung-Woo; Kang, Jin-Hyoung

    2013-08-01

    Patients with HPV-positive oropharyngeal cancer show better tumor response to radiation or chemotherapy than patients with HPV-negative cancer. HPV oncoprotein E6 binds and degrades a typically wild-type p53 protein product. However, HPV16 infection and p53 mutation infrequently coexist in a subset of HNSCCs. The purpose of this study was to investigate the mechanisms through which tumor biology and molecular genetic mechanisms change when two HPV-negative, p53-mutated oropharyngeal cell lines (YD8, non-disruptive p53 mutation; YD10B, disruptive p53 mutation) derived from patients with a history of heavy smoking are transfected with HPV E6 and E7 oncogenes in vitro. Transfection with HPV E6 and E7 oncogenes in YD8, reduced the abundance of proteins encoded by tumor suppressor genes, such as p-p53 and p-Rb. Cell proliferative activity was increased in the cells transfected with E6E7 compared to cells transfected with vector alone (P=0.09), whereas the invasiveness of E6E7-transfected cells was significantly reduced (P=0.02). cDNA microarray of the transfected cells with E6E7 showed significant changes in mRNA expression in several signaling pathways, including focal adhesion, JAK-STAT signaling pathway, cell cycle and p53 signaling pathway. Regarding the qPCR array for the p53 signaling pathway, the mRNA expression of STAT1 was remarkably upregulated by 6.47-fold (P<0.05); in contrast, IGF-1R was significantly downregulated by 2.40-fold in the YD8-vector compared toYD8-E6E7 (P<0.01). Finally, data collected from these two array experiments enabled us to select two genes, STAT1 and IGF-1R, for further study. In immunohistochemical study, nuclear STAT1 expression was slightly higher in HPV-positive compared to HPV-negative oropharyngeal tumors (P=0.18); however, cytoplasmic STAT1 was significantly lower in HPV-positive cases (P=0.03). IGF-1R expression levels were remarkably lower in HPV-positive compared to HPV-negative cases (P=0.01). Our data suggest that

  8. 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

  9. 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.

  10. Telomerase activity, P53 mutation and Ki-ras codon 12 point mutation of the peripheral blood in patients with hepato pancreato biliary diseases

    PubMed Central

    Chijiiwa, Kazuo; Torata, Nobuhiro; Kinoshita, Moritoshi; Tanaka, Masao

    2002-01-01

    Background With progress in molecular biology, the presence of telomerase activity, P53 mutation and Ki-ras codon 12 point mutation has been reported in malignant tumours of the liver, pancreas and biliary tree. The purpose of this paper is to clarify the clinical implications of finding these three biomarkers in the peripheral blood of affected patients. Methods Telomerase activity, P53 mutation, and Ki-ras codon 12 point mutation in the peripheral blood were examined among 86 patients with hepato pancreato biliary disease, both benign and malignant, and the results were compared with clinical findings. Results Of 20 patients with benign conditions, only one patient with intraductal papillary adenoma showing severe dysplasia exhibited a biomarker (telomerase activity) in the peripheral blood. In total, there were 66 patients with various HPB carcinomas. Of 56 cancer patients studied pre-operatively, 16 were positive for more than one biomarker, 13 were positive for telomerase activity, 4 for P53 mutation (three at exon 7 and another at exon 8), and 2 for Kiras codon 12 point mutation (both in the second letter). Twelve of the 16 biomarker-postiive patients had stage IV disease as opposed to 23 of 40 biomarker-negative patients. The resectability rate of the cancer was 38% in positive patients and 50% in negative patients. The one-year survival rate after resection was zero in positive patients and 15% in negative patients, but the difference was not significant (P=0.65). Of 32 patients with liver metastasis at the time of the molecular examination, eight were positive and 24 negative. Of 34 patients without liver metastasis, nine were positive and 25 negative. The development of subsequent liver metastases in those without them at the start was not significantly different in those with and without biomarkers (56 vs 36%: P=0.31). Conclusions The three novel biomarkers of the peripheral blood seemed to be of little value for screening of early malignant HPB

  11. Amino-terminal p53 mutations lead to expression of apoptosis proficient p47 and prognosticate better survival, but predispose to tumorigenesis.

    PubMed

    Phang, Beng Hooi; Othman, Rashidah; Bougeard, Gaelle; Chia, Ren Hui; Frebourg, Thierry; Tang, Choong Leong; Cheah, Peh Yean; Sabapathy, Kanaga

    2015-11-17

    Whereas most mutations in p53 occur in the DNA-binding domain and lead to its functional inactivation, their relevance in the amino-terminal transactivation domain is unclear. We show here that amino-terminal p53 (ATp53) mutations often result in the abrogation of full-length p53 expression, but concomitantly lead to the expression of the amino-terminally truncated p47 isoform. Using genetically modified cancer cells that only express p47, we demonstrate it to be up-regulated in response to various stimuli, and to contribute to cell death, through its ability to selectively activate a group of apoptotic target genes. Target gene selectivity is influenced by K382 acetylation, which depends on the amino terminus, and is required for recruitment of selective cofactors. Consistently, cancers capable of expressing p47 had a better overall survival. Nonetheless, retention of the apoptotic function appears insufficient for tumor suppression, because these mutations are also found in the germ line and lead to Li-Fraumeni syndrome. These data from ATp53 mutations collectively demonstrate that p53's apoptosis proficiency is dispensable for tumor suppression, but could prognosticate better survival.

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

    PubMed Central

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

    2002-01-01

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

  13. Analysis of fused maxillary incisor dentition in p53-deficient exencephalic mice

    PubMed Central

    KAUFMAN, M. H.; KAUFMAN, D. B.; BRUNE, R. M.; STARK, M.; ARMSTRONG, J. F.; CLARKE, A. R.

    1997-01-01

    Out of a total of 21 exencephalic p53-deficient embryonic and newborn mice, 6 (28.6%) possessed fused maxillary incisor teeth. On histological analysis of the 5 examples seen on day 19.5 of gestation and newborn mice, 3 varieties were observed: an example of ‘simple’ fusion, 3 examples of simple fusion each of which contained a ‘dens in dente’ (‘tooth within a tooth’), and a single example in which the fused teeth were associated with a median supernumerary incisor tooth which, while deeply indenting the labial surface of the fused teeth, was in all locations a completely separate unit. 3-D reconstructions of the fused teeth demonstrated that they were all of the fusio subtotalis variety. No gross abnormalities were observed in the other dentition in these mice. It is noted that in mice fused maxillary incisor teeth are relatively commonly associated with both hypervitaminosis A-induced and trypan blue-induced exencephaly. It is believed that the presence of dens in dente within fused maxillary incisor teeth has only once been reported in mice, and the association between fused maxillary incisor teeth and a median supernumerary incisor tooth has not previously been reported in this species. PMID:9279659

  14. Detection of the anti-P53 antibodies in dogs with tumors.

    PubMed

    Kanaya, Noriko; Okuda, Masaru; Toyama, Naomi; Oikawa, Tatsuo; Inokuma, Hisashi; Morimoto, Masahiro; Hayashi, Toshiharu; Une, Satoshi; Nakaichi, Munekazu; Taura, Yasuho; Tsujimoto, Hajime; Onishi, Takafumi

    2002-11-01

    To detect the anti-P53 antibodies of dogs with tumors, a GST-recombinant canine (rc) P53 fusion protein was expressed and purified. Immunoblot analysis was performed using this GST-rcP53 fusion protein as an antigen and serum samples from dogs suffering from tumors as primary antibodies. Out of 16 serum samples obtained from various tumor cases, four samples showed reaction with GST-rcP53. In contrast, serum from other 12 dogs with tumors, four dogs with non-neoplastic diseases and two control healthy dogs (as controls) did not show any reaction with GST-rcP53 in immunoblotting. The p53 gene mutation and the P53 protein expression were examined, using the tumor tissues to explore the relationship between the existence of the GST-rcP53 bands, gene mutations of p53 and the accumulation of P53 protein. One case, which showed a clear GST-rcP53 band, had a point mutation of the p53 cDNA and showed nuclear accumulation of P53 protein. These results suggest that the anti-P53 antibodies are also produced in tumor dogs with p53 gene mutations.

  15. Development of functionalized nanodiamond fluorescence detection platform: Analysis the specific promoter regulated by p53

    NASA Astrophysics Data System (ADS)

    Wu, Diansyue; Chu, Hsueh-Liang; Chuang, Hung; Lu, Yu-Ning; Ho, Li-Ping; Li, Hsing-Yuan; Hsu, Ming-Hua; Chang, Chia-Ching

    2014-03-01

    Nanodiamond (ND) is one of the biocompatible nanomaterials with large tunable surface for chemical modification. It possesses unique mechanical, spectroscopy, and thermal properties. It is an excellent molecular vehicle to deliver specific molecules in biological system. The green fluorescent protein (GFP) is a protein that emits strong green fluorescence when it is excited by ultra-violet to blue light. It makes GFP a good indicator. By combining ND-GFP, a visible biocompatible delivery system will be developed. p53 is a tumor suppressor protein encoded by the TP53 gene. P53 plays an important role in apoptosis, genomic stability, and inhibition of angiogenesis by interacting with specific DNA sequence of promoter of related genes. In this study, a p53 functionalized ND-GFP will be developed. This complex can recognize the specific DNA sequence of promoter and the intermolecular interactions can be monitored directly by fluorescence and Raman spectroscopy both in vivo and in vitro.

  16. Caffeine Suppresses Apoptosis of Bladder Cancer RT4 Cells in Response to Ionizing Radiation by Inhibiting Ataxia Telangiectasia Mutated-Chk2-p53 Axis

    PubMed Central

    Zhang, Zhe-Wei; Xiao, Jing; Luo, Wei; Wang, Bo-Han; Chen, Ji-Min

    2015-01-01

    Background: Caffeine suppresses ataxia telangiectasia and Rad3 related and ataxia telangiectasia mutated (ATM) activities; ATM is the major kinase for DNA damage detection. This study aimed to investigate the effects of caffeine on DNA damage responses in cells from the bladder cancer cell line RT4 those were exposed to ionizing radiation (IR). Methods: Immunofluorescent staining was performed to investigate changes in the proteins involved in DNA damage responses with or without caffeine. A mouse xenograft model was used to study the effects of caffeine on the DNA damage responses. Western blotting was used to investigate the effects of caffeine pretreatment on the ATM-Chk2-p53-Puma axis, while real-time polymerase chain reaction (RT-PCR) assessed changes in messenger RNA levels of p53 and downstream targets responding to IR. Finally, terminal deoxynucleotidyl transferase-dUTP nick end labeling assay. Western blotting and colony formation assay were used to measure the effects of caffeine on radiation-related apoptosis. All of the data were analyzed with a two-tailed Student's t-test. Results: Immunofluorescent staining showed that caffeine pretreatment profoundly suppressed the formation of γH2AXand p53-binding protein 1 foci in RT4 cells in response to irradiation. Cellular and animal experiments suggested that this suppression was mediated by suppression of the ATM-Chk2-p53-Puma DNA damage-signaling axis. RT-PCR indicated caffeine also attenuated transactivation of p53 and p53-inducible genes. The colony formation assay revealed that caffeine displayed radioprotective effects on RT4 cells in response to low-dose radiation compared to the radiosensitization effects on T24 cells. Conclusion: Caffeine may inhibit IR-related apoptosis of bladder cancer RT4 cells by suppressing activation of the ATM-Chk2-p53-Puma axis. PMID:26521794

  17. [Assessment of prognosis and p 53 mutations in patients with multiple tumors of the lung; intrapulmonary metastasis or double primary cancers?].

    PubMed

    Osaki, T; Oyama, T; Takenoyama, M; Taga, S; So, T; Yamashita, T; Nakata, S; Sugio, K; Yasumoto, K

    2002-01-01

    To assess whether a satellite lesion in the primary-tumor lobe is intrapulmonary metastasis from primary cancer (pm 1) or they are double primary lung cancers, we examined the postoperative prognosis of patients with pm 1 and the p 53 genetic differentiation between a satellite lesion and a primary lesion. Of 772 consecutive patients with N0-2M0 non-small cell lung cancer who underwent surgical resections between 1979 and 2000, 31 patients had a satellite lesion in the primary-tumor lobe. The 5-year survival rate was 26.3% in the pm 1 (+) T 4 group (n = 37), 14.7% in the pm 1 (-) T 4 group (n = 43), and 32.5% in the T 3 group (n = 132), suggesting that pm 1 cases should be classified as T 3. We examined 16 of 37 patients with pm 1 for mutations of the p 53 gene occurring exons 5 through 8 by the fluorescence-based polymerase chain reaction single-strand conformation polymorphism. Seven of the 16 patients analyzed had at least one p 53 mutations in their tumors. The mutational status of the p 53 gene was discordant in 5 patients, suggesting they were double primary lung cancers. The mutational status including DNA sequencing of the p 53 gene was concordant in 2 patients, suggesting they were intrapulmonary metastases. It remains arguable in the TNM staging system whether a satellite lesion in the primary-tumor lobe is intrapulmonary metastasis from primary cancer or they are double primary lung cancers.

  18. A novel p53 mutant found in iatrogenic urothelial cancers is dysfunctional and can be rescued by a second-site global suppressor mutation.

    PubMed

    Odell, Adam F; Odell, Luke R; Askham, Jon M; Alogheli, Hiba; Ponnambalam, Sreenivasan; Hollstein, Monica

    2013-06-07

    Exposure to herbal remedies containing the carcinogen aristolochic acid (AA) has been widespread in some regions of the world. Rare A→T TP53 mutations were recently discovered in AA-associated urothelial cancers. The near absence of these mutations among all other sequenced human tumors suggests that they could be biologically silent. There are no cell banks with established lines derived from human tumors with which to explore the influence of the novel mutants on p53 function and cellular behavior. To investigate their impact, we generated isogenic mutant clones by integrase-mediated cassette exchange at the p53 locus of platform (null) murine embryonic fibroblasts and kidney epithelial cells. Common tumor mutants (R248W, R273C) were compared with the AA-associated mutants N131Y, R249W, and Q104L. Assays of cell proliferation, migration, growth in soft agar, apoptosis, senescence, and gene expression revealed contrasting outcomes on cellular behavior following introduction of N131Y or Q104L. The N131Y mutant demonstrated a phenotype akin to common tumor mutants, whereas Q104L clone behavior resembled that of cells with wild-type p53. Wild-type p53 responses were restored in double-mutant cells harboring N131Y and N239Y, a second-site rescue mutation, suggesting that pharmaceutical reactivation of p53 function in tumors expressing N131Y could have therapeutic benefit. N131Y is likely to contribute directly to tumor phenotype and is a promising candidate biomarker of AA exposure and disease. Rare mutations thus do not necessarily point to sites where amino acid exchanges are phenotypically neutral. Encounter with mutagenic insults targeting cryptic sites can reveal specific signature hotspots.

  19. Association of p53 binding and immortalization of primary C57BL/6 mouse embryo fibroblasts by using simian virus 40 T-antigen mutants bearing internal overlapping deletion mutations.

    PubMed Central

    Kierstead, T D; Tevethia, M J

    1993-01-01

    To more precisely map the immortalization and p53 binding domains of T antigen, a large series of overlapping deletion mutations were created between codons 251 to 651 by utilizing a combination of Bal 31 deletion and oligonucleotide-directed mutagenesis. Immortalization assay results indicated that amino acids (aa) 252 to 350, 400, and 451 to 532 could be removed without seriously compromising immortalization, although the appearance of immortal colonies was delayed in some cases. Western immunoblotting experiments indicated that the p53 binding capacities of T antigen produced by mutants missing aa 252 to 300, 301 to 350, 400, or 451 to 532 were only slightly reduced relative to that of wild-type T antigen. Within the limits of this deletion analysis, the immortalization and p53 binding domains appear to be colinear and, in fact, may represent two aspects of the same domain. This deletion analysis eliminates the entire zinc finger domain (aa 302 to 320), a small portion of the leucine-rich region (aa 345 to 350), and a large portion of the ATP binding domain (aa 451 to 528) as participants in p53 binding or in the immortalization process. The results also show that removal of T antigen amino acids within the region 451 to 532 appears to alter the capacity of newly synthesized but not older T antigen and p53 molecules to form complexes. Images PMID:8383212

  20. Gain of function in the mouse model of a recurrent mutation p53(N236S) promotes the formation of double minute chromosomes and the oncogenic potential of p19(ARF).

    PubMed

    Zhao, Lanjun; Wang, Boyuan; Zhao, Xilong; Wu, Xiaoming; Zhang, Qiushi; Wei, Chuanyu; Shi, Minling; Li, Yunlong; Tang, Wenru; Zhang, Jihong; Yang, Julun; Singh, Sanjay Kumar; Jia, Shuting; Luo, Ying

    2017-09-26

    The mutation p53(N236S) (p53S) has been identified as one of the recurrent mutations in human cancers by TCGA database. Our in vitro data revealed the oncogenic gain of function of p53S. To understand the function of p53S in vivo, we generated the p53S knock-in mouse. The p53(S/S) mice manifested highly invasive lymphomas and metastatic sarcomas with dramatically increased double minute chromosomes. The survival curve, the incidence of tumors and the tumor spectrum of p53(S/S) mice is very similar to the p53(R172H) mouse model. The p53(S/+) mice showed delayed onset of tumorigenesis and a high metastasis rate (40%) and low loss of heterozygosity rate (2/16). The activation of CDKN2A pathway in p53(S/S) MEF and tumors, and the accumulation of p19(ARF) protein in tumor tissues suggested p19(ARF) might contribute to the accumulation of mutant p53S protein in the tumor and promote tumorigenesis. The high expression of p19(ARF) correlated with mutant p53 accumulation and tumor progression, suggesting a dual role of p19(ARF) in tumor promotion or suppression that might depend on the p53 mutation status in tumor cells. The oncogenic gain of function of this recurrent mutation p53S prompts the reconsideration of p53 mutations function that occurs at a low frequency. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  1. P53 mutations in triple negative breast cancer upregulate endosomal recycling of epidermal growth factor receptor (EGFR) increasing its oncogenic potency.

    PubMed

    Shapira, Iuliana; Lee, Annette; Vora, Reena; Budman, Daniel R

    2013-11-01

    There is no available targeted therapy for triple-negative or its more aggressive subtype, basal-like breast cancer. Multiple therapeutic strategies based on translational knowledge have not improved the treatment options for triple negative patients. As understanding of molecular pathways that drive tumor development is rapidly increasing, it is imperative to adapt our treatment strategies to perturbations in molecular pathways driving the malignant process. Basal-like breast cancers over-express EGFR (without mutations or EGFR gene amplifications) and have p53 mutations. While EGFR drives the malignant behavior in triple negative breast cancer (TNBC), anti-EGFR therapies have fallen short of the expected results in clinical trials. Here we bring evidence that the less than optimal results of the anti-EGFR therapies may be explained in part by the increased potency of the EGFR signaling due to increased endosomal recycling. The functional connection between EGFR and endosomal trafficking in TNBC is mutant p53 found in the most aggressive forms of TNBC. Mutant p53 acquires oncogenic functions and binds p63 protein, a member of p53 family with tumor suppressor activities. In the absence of functional p63 there is an upregulation of endosomal recycling EGFR and integrin to the membrane with increased proinvasive abilities of cancer cells. Blocking endosomal trafficking combined with anti-EGFR treatments may result in better clinical outcomes in TNBC.

  2. p53 expression as a prognostic factor in upper urinary tract urothelial carcinoma: a systematic review and meta-analysis.

    PubMed

    Lee, Joo Yong; Cho, Kang Su; Diaz, Richilda Red; Choi, Young Deuk; Choi, Hong Yong

    2015-01-01

    To conduct a meta-analysis examining p53 expression as a potential risk factor in upper urinary tract urothelial carcinoma (UUT-UC) and to systematically review the available data. A comprehensive literature review was performed from January 1991 to August 2012, using search engines such as PubMed, EMBASE, Cochrane Library and KoreaMed. All retrieved references were manually reviewed, and two authors independently extracted the data. The quality of case-control and cohort studies was assessed using the Scottish Intercollegiate Guidelines Network (SIGN) checklists. Heterogeneity among studies was examined using the Q statistics and Higgins' I(2) statistic. Of 302 abstracts of original research studies, nine case-control trials fit our criteria for inclusion in the analysis. Of the nine articles included, four scored 'low' and five scored 'modest' in the quality assessment performed according to the SIGN checklists. Analysis of the correlation between different factors and p53 expression in UUT-UC showed that pathologic stage (≥pT3 or p53 and non-p53 groups (OR = 2.720, p < 0.001). Statistically significant correlations were also detected between p53 expression and histologic grade (OR = 4.507, p < 0.001) and female gender (OR = 2.724, p < 0.001). The results of our meta-analysis suggest that p53 expression in UUT-UC was correlated with advanced pathologic stage, high histologic grade and female gender. © 2014 S. Karger AG, Basel.

  3. Association of p53 codon72 Arg>Pro polymorphism with susceptibility to nasopharyngeal carcinoma: evidence from a case-control study and meta-analysis.

    PubMed

    Sahu, S K; Chakrabarti, S; Roy, S D; Baishya, N; Reddy, R R; Suklabaidya, S; Kumar, A; Mohanty, S; Maji, S; Suryanwanshi, A; Rajasubramaniam, S; Asthana, M; Panda, A K; Singh, S P; Ganguly, S; Shaw, O P; Bichhwalia, A K; Sahoo, P K; Chattopadhyay, N R; Chatterjee, K; Kundu, C N; Das, A K; Kannan, R; Zorenpuii; Zomawia, E; Sema, S A; Singh, Y I; Ghosh, S K; Sharma, K; Das, B S; Choudhuri, T

    2016-05-09

    Tumor suppressor p53 is a critical player in the fight against cancer as it controls the cell cycle check point, apoptotic pathways and genomic stability. It is known to be the most frequently mutated gene in a wide variety of human cancers. Single-nucleotide polymorphism of p53 at codon72 leading to substitution of proline (Pro) in place of arginine (Arg) has been identified as a risk factor for development of many cancers, including nasopharyngeal carcinoma (NPC). However, the association of this polymorphism with NPC across the published literature has shown conflicting results. We aimed to conduct a case-control study for a possible relation of p53 codon72 Arg>Pro polymorphism with NPC risk in underdeveloped states of India, combine the result with previously available records from different databases and perform a meta-analysis to draw a more definitive conclusion. A total of 70 NPC patients and 70 healthy controls were enrolled from different hospitals of north-eastern India. The p53 codon72 Arg>Pro polymorphism was typed by polymerase chain reaction, which showed an association with NPC risk. In the meta-analysis consisting of 1842 cases and 2330 controls, it was found that individuals carrying the Pro allele and the ProPro genotype were at a significantly higher risk for NPC as compared with those with the Arg allele and the ArgArg genotype, respectively. Individuals with a ProPro genotype and a combined Pro genotype (ProPro+ArgPro) also showed a significantly higher risk for NPC over a wild homozygote ArgArg genotype. Additionally, the strength of each study was tested by power analysis and genotype distribution by Hardy-Weinberg equilibrium. The outcome of the study indicated that both allele frequency and genotype distribution of p53 codon72 Arg>Pro polymorphism were significantly associated with NPC risk. Stratified analyses based on ethnicity and source of samples supported the above result.

  4. Slow repair of bulky DNA adducts along the nontranscribed strand of the human p53 gene may explain the strand bias of transversion mutations in cancers.

    PubMed

    Denissenko, M F; Pao, A; Pfeifer, G P; Tang, M

    1998-03-12

    Using UvrABC incision in combination with ligation-mediated PCR (LMPCR) we have previously shown that benzo(a)pyrene diol epoxide (BPDE) adduct formation along the nontranscribed strand of the human p53 gene is highly selective; the preferential binding sites coincide with the major mutation hotspots found in human lung cancers. Both sequence-dependent adduct formation and repair may contribute to these mutation hotspots in tumor tissues. To test this possibility, we have extended our previous studies by mapping the BPDE adduct distribution in the transcribed strand of the p53 gene and quantifying the rates of repair for individual damaged bases in exons 5, 7, and 8 for both DNA strands of this gene in normal human fibroblasts. We found that: (i) on both strands, BPDE adducts preferentially form at CpG sequences, and (ii) repair of BPDE adducts in the transcribed DNA strand is consistently faster than repair of adducts in the nontranscribed strand, while repair at the major damage hotspots (guanines at codons 157, 248 and 273) in the nontranscribed strand is two to four times slower than repair at other damage sites. These results strongly suggest that both preferential adduct formation and slow repair lead to hotspots for mutations at codons 157, 248 and 273, and that the strand bias of bulky adduct repair is primarily responsible for the strand bias of G to T transversion mutations observed in the p53 gene in human cancers.

  5. Allele-specific PCR analysis of p53 codon 249 AGT transversion in liver tissues from patients with viral hepatitis.

    PubMed

    Kirby, G M; Batist, G; Fotouhi-Ardakani, N; Nakazawa, H; Yamasaki, H; Kew, M; Cameron, R G; Alaoui-Jamali, M A

    1996-09-27

    AGG to AGT mutations in codon 249 of the p53 tumor-suppressor gene are frequently observed in hepatocellular carcinomas (HCC) from areas where exposure to aflatoxin B1 (AFB) occurs. We developed a sensitive allele-specific polymerase chain reaction (AS-PCR) assay to detect this point mutation in non-neoplastic human liver tissues. Three oligonucleotide primers, 1 specific for the mutant allele and 2 specific for the wild-type allele were used. The mutant allele primer differed from the wild-type allele due to a G-to-T transversion in its terminal 3' nucleotide. The first stage involved amplification of exon 7 of p53 followed by a selective amplification of mutant codon 249 sequences. This method allowed for the detection of a mutant codon 249 allele in the presence of as many as 105 copies of the wild-type allele and was 100-fold more sensitive than the restriction fragment length polymorphism-PCR technique. We have applied this AS-PCR protocol to examine codon 249 AGT transversion in tumor and matched non-tumor liver samples from North American patients with hepatitis and from Mozambiquan patients exposed to AFB. Mutations were detected in 5 of 6 samples of non-neoplastic liver from Mozambiquan patients, all of whom were HBsAg- or HBcAg-positive and AFB-exposed. In contrast, no mutations were detected in non-neoplastic liver from North American patients with either HBV- or HCV-derived hepatitis and cirrhosis. This procedure is a simple and powerful approach for screening p53 codon 249 AGT mutation in heterogeneous non-neoplastic hepatocyte populations.

  6. AFB1 hepatocarcinogenesis is via lipid peroxidation that inhibits DNA repair, sensitizes mutation susceptibility and induces aldehyde-DNA adducts at p53 mutational hotspot codon 249

    PubMed Central

    Hu, Yu; Mehta, Manju; Desai, Dhimant; Amin, Shantu; Zheng, Yi; Tang, Moon-Shong

    2017-01-01

    Aflatoxin B1 (AFB1) contamination in the food chain is a major cause of hepatocellular carcinoma (HCC). More than 60% of AFB1 related HCC carry p53 codon 249 mutations but the causal mechanism remains unclear. We found that 1) AFB1 induces two types of DNA adducts in human hepatocytes, AFB1-8,9-epoxide-deoxyguanosine (AFB1-E-dG) induced by AFB1-E and cyclic α-methyl-γ-hydroxy-1,N2-propano-dG (meth-OH-PdG) induced by lipid peroxidation generated acetaldehyde (Acet) and crotonaldehyde (Cro); 2) the level of meth-OH-PdG is >30 fold higher than the level of AFB1-E-dG; 3) AFB1, Acet, and Cro, but not AFB1-E, preferentially induce DNA damage at codon 249; 4) methylation at –CpG- sites enhances meth-OH-PdG formation at codon 249; and 5) repair of meth-OH-PdG at codon 249 is poor. AFB1, Acet, and Cro can also inhibit DNA repair and enhance hepatocyte mutational sensitivity. We propose that AFB1-induced lipid peroxidation generated aldehydes contribute greatly to hepatocarcinogenesis and that sequence specificity of meth-OH-PdG formation and repair shape the codon 249 mutational hotspot. PMID:28212554

  7. Distinct in vitro sensitivity of p53-mutated and ATM-mutated chronic lymphocytic leukemia cells to ofatumumab and rituximab.

    PubMed

    Sebejova, Ludmila; Borsky, Marek; Jaskova, Zuzana; Potesil, David; Navrkalova, Veronika; Malcikova, Jitka; Sramek, Martin; Doubek, Michael; Loja, Tomas; Pospisilova, Sarka; Mayer, Jiri; Trbusek, Martin

    2014-10-01

    Abnormalities in ATM and TP53 genes represent important predictive factors in chronic lymphocytic leukemia (CLL); however, the efficacy of CD20 targeting immunotherapy is only poorly defined in the affected patients. Therefore, we tested the in vitro response to ofatumumab (OFA) and rituximab (RTX) in 75 CLL samples with clearly defined p53 or ATM inactivation. Using standard conditions allowing complement-dependent cytotoxicity, i.e., 10 μg/mL of antibodies and 20% active human serum, we observed clear differences among the tested genetic categories: ATM-mutated samples (n = 17) represented the most sensitive, wild-type samples (n = 31) intermediate, and TP53-mutated samples (n = 27) the most resistant group (ATM-mut vs. TP53-mut: P = 0.0005 for OFA and P = 0.01 for RTX). The response correlated with distinct levels of CD20 and critical complement inhibitors CD55 and CD59; CD20 level median was the highest in ATM-mutated and the lowest in TP53-mutated samples (difference between the groups P < 0.01), while the total level of complement inhibitors (CD55 plus CD59) was distributed in the opposite manner (P < 0.01). Negligible response to both OFA and RTX was noted in all cultures (n = 10) tested in the absence of active serum, which strongly indicated that complement-dependent cytotoxicity was a principal cell death mechanism. Our study shows that (1) common genetic defects in CLL cells significantly impact a primary response to anti-CD20 monoclonal antibodies and (2) ATM-mutated patients with currently poor prognosis may potentially benefit from immunotherapy targeting CD20. Copyright © 2014 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

  8. Analysis of central regulatory pathways in p53-deficient primary cultures of malignant fibrous histiocytoma exposed to ifosfamide.

    PubMed

    Schlott, Thilo; Taubert, Helge; Fayyazi, Afshin; Schweyer, Stefan; Bartel, Frank; Korabiowska, Monika; Brinck, Ulrich

    2004-01-01

    Soft tissue sarcomas frequently carry p53 mutations reducing chemotherapeutical response. Especially malignant fibrous histiocytoma (MFH) reveals a reduced ifosfamide (IF) chemosensitivity when compared to other sarcoma entities. This is the first study to analyze MFH cells for the effects of IF on the expression of the pathways P16-CDK4-Rb and P14ARF-MDM2-P73 regulating cell cycle. The aim was to identify candidate genes possibly involved in the anti-apoptotic response of p53-deficient MFH cells during chemotherapy. PCR, real-time RT-PCR and confocal laser scanning microscopy were applied on primary cultures of MFH cells containing defective p53 genes. The cultures were treated with different concentrations of IF. A non-treated MFH culture served as negative control. A threshold concentration of IF (100 microM) was determined sparing the majority of the cells (99%), whereas higher IF quantities caused complete apoptosis. Data collected over a period of 48 h showed that the MFH cells surviving 100 microM IF overexpressed the kinase gene CDK4 and oncogene MDM2 by a factor of 63. A similar strong increase was observed at the protein level for both proteins. In contrast, the other proteins analyzed were not detectable. Additionally, the MFH cells induced complex patterns of MDM2 mRNA splicing and an abnormal mRNA transcript carrying a novel MDM2 missense mutation. These effects were neither observed in the non-treated culture nor in cultures completely inducing spontaneous apoptosis. Therefore, we speculate that the induction of the gene CDK4, and especially of MDM2, is involved in anti-apoptotic mechanisms of p53-negative MFH cells tolerating IF in vitro. Further experiments are necessary to test whether the novel candidate genes favor development of chemoresistance and whether MDM2 mRNA splicing variants contribute to this process in vivo.

  9. The incidence of germline p53 mutations in 53 Li-Fraumeni-like families and in individuals with multiple primary tumors

    SciTech Connect

    Eeles, R.; Seal, S.; Horwich, A.

    1994-09-01

    The classical Li-Fraumeni Syndrome (LFS) is the association of sarcoma (at <45 years) with either sarcoma, breast cancer, brain tumor, leukemia or adrenal carcinoma in a first degree relative and cancer (at <45) or sarcoma (any age) in a close relative. Prostate cancer, testicular cancer and melanoma are now considered also to be part of LFS, and members of such families often have multiple tumors. We have defined Li-Fraumeni-like families (LFL) as having at least two relatives affected with the tumors in the extended definition of LFS, but not fulfilling the classical definition. We analyzed exons in 1 through 11 of the p53 gene from blood DNA from affected individuals in 53 LFL families by single strand conformational polymorphism. Four of the 53 had abnormalities, in exons 5, 7 and 8, confirmed by sequencing. We also studied 11 individuals with two primary tumors, both of which are part of LFS and 22 individuals with 3 primary tumors at any site (excluding multiple colonic tumors). Two of the 33 (6%) individuals has germline mutations; both were members of LFL families and both had sarcoma as one of their primaries. Germline p53 mutations occur in 8% of LFL families and in patients with multiple primaries; p53 mutations are restricted to those in LFL/LFS families.

  10. CpG methylation of ubiquitin carboxyl-terminal hydrolase 1 (UCHL1) and P53 mutation pattern in sporadic colorectal cancer.

    PubMed

    Abdelmaksoud-Dammak, Rania; Saadallah-Kallel, Amena; Miladi-Abdennadher, Imen; Ayedi, Lobna; Khabir, Abdelmajid; Sallemi-Boudawara, Tahia; Frikha, Mounir; Daoud, Jamel; Mokdad-Gargouri, Raja

    2016-02-01

    The ubiquitin-proteasome system plays an essential regulatory role in various cellular processes. Besides its involvement in normal cellular functions, the alteration of proteasomal activity contributes to the pathological states of several clinical disorders, including cancer. Aberrant methylation of the CpG islands has been reported as an alternative way to inactivate gene expression involved in the ubiquitination process and thus protein degradation in tumor tissues. In this study, we aimed to determine the CpG methylation pattern of the UCHL1 promoter, as well as the mutation spectrum and the expression pattern of P53 in sporadic colorectal cancer (CRC) from Tunisian patients. We found that UCHL1 was methylated in 68.57 % and correlated significantly with lymph node metastasis (P = 0.029) and transcriptional silencing in tumor tissues (P = 0.013). Mutation screening of exons 5-9 of P53 showed that 42.85 % of cases harbor somatic mutation and are positively correlated with the methylated pattern of UCHL1 (P = 0.001). Furthermore, cytoplasmic accumulation of P53 was strongly associated with the unmethylated UCHL1 profile (P = 0.006), supporting the relationship between these two proteins in CRC.

  11. p21WAF1/Cip1 expression is associated with cell differentiation but not with p53 mutations in squamous cell carcinomas of the larynx.

    PubMed

    Nadal, A; Jares, P; Cazorla, M; Fernández, P L; Sanjuan, X; Hernandez, L; Pinyol, M; Aldea, M; Mallofré, C; Muntané, J; Traserra, J; Campo, E; Cardesa, A

    1997-10-01

    p21WAF1/Cip1 is a recently identified gene involved in cell cycle regulation through cyclin-CDK-complex inhibition. The expression of this gene in several cell lines seems to be induced by wild-type, but not mutant, p53. p21WAF1/Cip1 expression has been studied at both mRNA and protein levels in a series of 49 normal mucosae and squamous cell carcinomas of the larynx. A significant association was found between mRNA and protein expression in tumours (P < 0.0001). p21WAF1/Cip1 expression was strongly associated with squamous cell differentiation of carcinomas, because six of seven (86 per cent) undifferentiated carcinomas (grade 4) showed very low levels of p21WAF1/Cip1 expression, whereas 41 out of 42 (98 per cent) carcinomas with squamous cell differentiation (grades 1-3) had normal or high levels of p21WAF1/Cip1 expression (P < 0.0001). In addition, p21WAF1/Cip1 expression was topologically related to the squamous differentiation of tumour cells with a distribution similar to that seen in normal squamous epithelium. No correlation was found between p21WAF1/Cip1 expression and the global S-phase of the carcinomas. p53 mutations (exons 5-9) were found in ten carcinomas with p21WAF1/Cip1 expression, but no p53 mutations were detected in three p21WAF1/Cip1-negative tumours. In conclusion, p21WAF1/Cip1 expression is frequently upregulated in squamous cell carcinomas of the larynx and is associated with tumour cell differentiation. p21WAF1/Cip1 expression in these tumours is independent of p53 gene mutations.

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

    DTIC Science & Technology

    1997-10-01

    We originally proposed the Differential Display method (Liang and Pardee 1992) to identify genes that are modulated by p53 and BRCA1 deficiency. As...retroviral delivery of tetracycline-inducible genes in a single autoregulatory cassette. Proc Natl Acad Sci U S A 93:5185-5190 (1996). Liang P, Pardee A...Shoemaker A, Dove W. ApcMin: a mouse model for intestinal and mammary tumorigenesis. Eur J Cancer 3 1A: 1061-4 (1995). Moser A, Mattes E, Dove W, Lindstrom M

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

    PubMed Central

    Dumaz, N; Drougard, C; Sarasin, A; Daya-Grosjean, L

    1993-01-01

    The UV component of sunlight is the major carcinogen involved in the etiology of skin cancers. We 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 good 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), we 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-->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. Images Fig. 1 PMID:8248141

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

    SciTech Connect

    Dumaz, N.; Drougard, C.; Sarasin, A.; Daya-Grosjean, L. )

    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 good 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.

  15. Whole Genome Pathway Analysis Identifies an Association of Cadmium Response Gene Loss with Copy Number Variation in Mutant p53 Bearing Uterine Endometrial Carcinomas

    PubMed Central

    Stupack, Dwayne G

    2016-01-01

    Background Massive chromosomal aberrations are a signature of advanced cancer, although the factors promoting the pervasive incidence of these copy number alterations (CNAs) are poorly understood. Gatekeeper mutations, such as p53, contribute to aneuploidy, yet p53 mutant tumors do not always display CNAs. Uterine Corpus Endometrial Carcinoma (UCEC) offers a unique system to begin to evaluate why some cancers acquire high CNAs while others evolve another route to oncogenesis, since about half of p53 mutant UCEC tumors have a relatively flat CNA landscape and half have 20–90% of their genome altered in copy number. Methods We extracted copy number information from 68 UCEC genomes mutant in p53 by the GISTIC2 algorithm. GO term pathway analysis, via GOrilla, was used to identify suppressed pathways. Genes within these pathways were mapped for focal or wide distribution. Deletion hotspots were evaluated for temporal incidence. Results Multiple pathways contributed to the development of pervasive CNAs, including developmental, metabolic, immunological, cell adhesion and cadmium response pathways. Surprisingly, cadmium response pathway genes are predicted as the earliest loss events within these tumors: in particular, the metallothionein genes involved in heavy metal sequestration. Loss of cadmium response genes were associated with copy number changes and poorer prognosis, contrasting with 'copy number flat' tumors which instead exhibited substantive mutation. Conclusion Metallothioneins are lost early in the development of high CNA endometrial cancer, providing a potential mechanism and biological rationale for increased incidence of endometrial cancer with cadmium exposure. Developmental and metabolic pathways are altered later in tumor progression. PMID:27391266

  16. Comparative transcriptional pathway bioinformatic analysis of dietary restriction, Sir2, p53 and resveratrol life span extension in Drosophila.

    PubMed

    Antosh, Michael; Whitaker, Rachel; Kroll, Adam; Hosier, Suzanne; Chang, Chengyi; Bauer, Johannes; Cooper, Leon; Neretti, Nicola; Helfand, Stephen L

    2011-03-15

    A multiple comparison approach using whole genome transcriptional arrays was used to identify genes and pathways involved in calorie restriction/dietary restriction (DR) life span extension in Drosophila. Starting with a gene centric analysis comparing the changes in common between DR and two DR related molecular genetic life span extending manipulations, Sir2 and p53, lead to a molecular confirmation of Sir2 and p53's similarity with DR and the identification of a small set of commonly regulated genes. One of the identified upregulated genes, takeout, known to be involved in feeding and starvation behavior, and to have sequence homology with Juvenile Hormone (JH) binding protein, was shown to directly extend life span when specifically overexpressed. Here we show that a pathway centric approach can be used to identify shared physiological pathways between DR and Sir2, p53 and resveratrol life span extending interventions. The set of physiological pathways in common among these life span extending interventions provides an initial step toward defining molecular genetic and physiological changes important in life span extension. The large overlap in shared pathways between DR, Sir2, p53 and resveratrol provide strong molecular evidence supporting the genetic studies linking these specific life span extending interventions.

  17. Mitofusin-2 is a novel direct target of p53

    SciTech Connect

    Wang, Weilin; Cheng, Xiaofei; Lu, Jianju; Wei, Jianfeng; Fu, Guanghou; Zhu, Feng; Jia, Changku; Zhou, Lin; Xie, Haiyang; Zheng, Shusen

    2010-10-01

    Research highlights: {yields} Mfn2 is a novel target gene of p53. {yields} Mfn2 mRNA and protein levels can be up-regulated in a p53-dependent manner. {yields} Mfn2 promoter activity can be elevated by the p53 protein. {yields} P53 protein binds the Mfn2 promoter directly both in vitro and in vivo. -- Abstract: The tumor suppressor p53 modulates transcription of a number of target genes involved in cell cycle arrest, apoptosis, DNA repair, and other important cellular responses. Mitofusin-2 (Mfn2) is a novel suppressor of cell proliferation that may also exert apoptotic effects via the mitochondrial apoptotic pathway. Through bioinformatics analysis, we identified a p53 binding site in the Mfn2 promoter. Consistent with this, we showed that the p53 protein binds the Mfn2 promoter directly both in vitro and in vivo. Additionally, we found that Mfn2 mRNA and protein levels are up-regulated in a p53-dependent manner. Furthermore, luciferase assays revealed that the activity of the wild-type Mfn2 promoter, but not a mutated version of the promoter, was up-regulated by p53. These results indicate that Mfn2 is a novel p53-inducible target gene, which provides insight into the regulation of Mfn2 and its associated activities in the inhibition of cell proliferation, promotion of apoptosis, and modulation of tumor suppression.

  18. Comparison of p53 mutations between adenocarcinoma and squamous cell carcinoma of the lung: unique spectra involving G to A transitions and G to T transversions in both histologic types.

    PubMed

    Gao, Wei-Min; Mady, Hussam H; Yu, Guo-Ying; Siegfried, Jill M; Luketich, James D; Melhem, Mona F; Keohavong, Phouthone

    2003-05-01

    The p53 gene is frequently mutated in lung tumors, and mutations may be caused by both polycyclic aromatic hydrocarbons (PAHs) and nitrosamines found in tobacco smoke. The two major forms of lung cancer, adenocarcinoma (AC) and squamous cell carcinoma (SCC), are known to differ in the proportion of tumors exhibiting p53 mutation, and may also differ in the mutational spectra produced. Previous studies comparing p53 mutational spectra between AC and SCC of the lung have been limited by small sample size. We examined p53 mutations in exons 5-8 in 202 cases of AC and 82 cases of SCC from smoking lung cancer patients in the Western Pennsylvania region. The percent of cases with p53 mutation was significantly lower in ACs (40/202, 20%) compared to SCCs (29/82, 35%, P=0.006). The proportion of mutations present that were G to T transversions was not significantly different between the two tumor types (52% of p53 mutations in AC compared to 32% in SCC). G to A transitions either did not differ in frequency in the two types of lung cancer (20% of mutations in AC and 24% of mutations in SCC). A distinct spectrum was observed, however, in the p53 mutation pattern in the two types of lung cancer. ACs showed a strong preference for a mutational hotspot at codons 248 and 249, while squamous cell tumors showed mutational events spread throughout exons 5-8, with a preference for codon 267. Mutations at codon 267 in SCC were all C to T transitions that occurred at CpG sites. Both tumor types demonstrated preferential mutation of the non-transcribed strand (100% of all G to T transversions and 55% of the G to A transitions). These results suggest that p53 mutations in both types of lung tumors may arise from adduction by both PAHs and nitrosamines. Mutations arising in ACs appear selectively in regions of p53 that produce more rigid proteins, suggesting a drastic change in p53 function is needed to result in ACs, while less constrained changes in p53 function can result in SCCs

  19. Flavopiridol Potentiates the Cytotoxic Effects of Radiation in Radioresistant Tumor Cells in Which p53 is Mutated or Bcl-2 is Overexpressed

    SciTech Connect

    Hara, Takamitsu; Omura-Minamisawa, Motoko Kang, Yun; Cheng, Chao; Inoue, Tomio

    2008-08-01

    Purpose: Loss of the cell-cycle regulatory protein p53 or overexpression of the antiapoptotic protein Bcl-2 is associated with resistance to radiation in several types of cancer cells. Flavopiridol, a synthetic flavone, inhibits the growth of malignant tumors cells in vitro and in vivo through multiple mechanisms. The purpose of the present study is to clarify whether flavopiridol enhances the cytotoxic effects of radiation in tumor cells that contain dysfunction p53 or that overexpress Bcl-2. Methods and Materials: A human glioma cell line (A172/mp53) stably transfected with a plasmid containing mutated p53 and a human cervical cancer cell line (HeLa/bcl-2) transfected with a bcl-2 expression plasmid were used. Cells were incubated with flavopiridol for 24 h after radiation, and then cell viability was determined by a colony formation assay. Foci of phosphorylated histone H2AX were also evaluated as a sensitive indicator of DNA double-strand breaks. Results: Compared with the parental wild-type cells, both transfected cell lines were more resistant to radiation. Post-treatment with flavopiridol increased the cytotoxic effects of radiation in both transfected cell lines, but not in their parental wild-type cell lines. Post-treatment with flavopiridol inhibited sublethal damage repair as well as the repair of DNA double-strand breaks in response to radiation. Conclusions: Flavopiridol enhanced the cytotoxic effect of radiation in radioresistant tumor cells that harbor p53 dysfunction or Bcl-2 overexpression. A combination treatment of flavopiridol with radiation has the potential to conquer the radioresistance of malignant tumors induced by the genetic alteration of p53 or bcl-2.

  20. Evidence for selection against human lung cancers bearing p53 missense mutations which occur within the HLA A*0201 peptide consensus motif.

    PubMed

    Wiedenfeld, E A; Fernandez-Viña, M; Berzofsky, J A; Carbone, D P

    1994-03-01

    Short peptide fragments of intracellular proteins that fit a defined sequence motif bind to the most common human major histocompatibility complex class I molecule, HLA A*0201, and mediate killing by cytotoxic T-cells [D.F. Hunt et al., Science (Washington DC), 255: 1261-1263, 1992; K. Falk et al., Nature (Lond.), 351: 290-296, 1991]. The existence of such a motif allows prediction of whether novel peptides derived from mutant oncoporteins might be presented on the surface of cancer cells bearing that HLA allele. Clinical cancer might develop only when these mutations occur outside a major histocompatibility complex binding motif or in those cells that acquire defects in antigen presentation. Here, we find that missense mutations of p53 from a variety of tumors fall within the HLA A*0201 motif less often than would be expected if the location of mutations and motifs were independent. When we analyzed the HLA subtype of lung cancer cell lines with known p53 missense mutations, we found that all of the mutant oncopeptides predicted to be presentable by HLA A*0201 came from tumors that either did not carry the A*0201 allele or had lost that allele in the process of tumorigenesis. Presentation of mutant oncogene peptides on class I major histocompatibility complex might thus represent a physiologically significant selection pressure in the development of human cancer.

  1. Hot-spot mutations in the p53 gene of liver nodules induced in rats fed DL-ethionine with a methyl-deficient diet.

    PubMed Central

    Tsujiuchi, T.; Yeleswarapu, L.; Konishi, Y.; Lombardi, B.

    1997-01-01

    Male F-344 rats were fed for 15 weeks a methyl-deficient L-amino acid defined diet containing 0.05% DL-ethionine. Nodules protruding from the surface of the liver were dissected free of surrounding tissue, and polyadenylated RNA isolated from the nodules was reverse transcribed. The region of the p53 gene comprising codons 120-290 was amplified by the polymerase chain reaction, and cDNAs were sequenced. Mutations were detected in nodules obtained from 7 of 12 rats. In all seven cases, the same two point mutations were present. The first was at the first base of codon 246 and consisted of a C-->T transition (C:G-->T:A, Arg-->Cys), while the second was at the second base of codon 247 and consisted of a G-->T transversion (G:C-->T:A, Arg-->Leu). It is concluded that the hepatocarcinogen ethionine induces specific hot-spot p53 gene mutations; this is in contrast to the mutations at various sites previously observed to occur in rats fed a hepatocarcinogenic methyl-deficient diet alone. The results also provide the first evidence that ethionine is mutagenic in the rat. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:9218726

  2. Regulation of Mutant p53 Protein Expression.

    PubMed

    Vijayakumaran, Reshma; Tan, Kah Hin; Miranda, Panimaya Jeffreena; Haupt, Sue; Haupt, Ygal

    2015-01-01

    For several decades, p53 has been detected in cancer biopsies by virtue of its high protein expression level which is considered indicative of mutation. Surprisingly, however, mouse genetic studies revealed that mutant p53 is inherently labile, similar to its wild type (wt) counterpart. Consistently, in response to stress conditions, both wt and mutant p53 accumulate in cells. While wt p53 returns to basal level following recovery from stress, mutant p53 remains stable. In part, this can be explained in mutant p53-expressing cells by the lack of an auto-regulatory loop with Mdm2 and other negative regulators, which are pivotal for wt p53 regulation. Further, additional protective mechanisms are acquired by mutant p53, largely mediated by the co-chaperones and their paralogs, the stress-induced heat shock proteins. Consequently, mutant p53 is accumulated in cancer cells in response to chronic stress and this accumulation is critical for its oncogenic gain of functions (GOF). Building on the extensive knowledge regarding wt p53, the regulation of mutant p53 is unraveling. In this review, we describe the current understanding on the major levels at which mutant p53 is regulated. These include the regulation of p53 protein levels by microRNA and by enzymes controlling p53 proteasomal degradation.

  3. p53: out of Africa.

    PubMed

    Lane, David

    2016-04-15

    Somatic mutations in the tumor suppressor gene p53 occur in more than half of all human cancers. Rare germline mutations result in the Li-Fraumeni cancer family syndrome. In this issue ofGenes&Development, Jennis and colleagues (pp. 918-930) use an elegant mouse model to examine the affect of a polymorphism, P47S (rs1800371), in the N terminus of p53 that is found in Africans as well as more than a million African Americans. Remarkably, the single nucleotide change causes the mice to be substantially tumor-prone compared with littermates, suggesting that this allele causes an increased risk of developing cancer. The defect in p53 function is traced to a restriction in downstream gene regulation that reduces cell death in response to stress.

  4. P53 codon 72 Arg/Pro polymorphism and lung cancer risk in Asians: an updated meta-analysis.

    PubMed

    Wang, Siyang; Lan, Xingang; Tan, Sheng; Wang, Siwen; Li, Yu

    2013-10-01

    The polymorphism of p53 codon 72, a transversion of G to C (Arg to Pro), has been demonstrated to be associated with the risk for lung cancer. However, individual studies conducted in Asians have provided conflicting and inconclusive findings. Thus, we performed a meta-analysis by pooling all currently available case-control studies to estimate the effect of p53 codon 72 Arg/Pro polymorphism on the development of lung cancer. The pooled odds ratios (ORs) with the corresponding 95 % confidence intervals (95 %CIs) were calculated to assess this effect. A total of 14 individual studies involving 7,929 cases and 5,924 controls were included into this meta-analysis according to the inclusion criteria. The overall OR for the dominant genetic model indicated that the p53 codon 72 Arg/Pro variant was positively correlated with lung cancer risk (ORArg/Pro + Pro/Pro vs. Arg/Arg = 1.14, 95 %CI 1.07-1.23, P OR < 0.001). Similar results were found in the stratified analysis of population-based studies. The histological types of lung cancer and smoking status seemed to exert no effect on the lung cancer risk. Sensitivity analysis confirmed the stability of the above findings. The updated meta-analysis suggests that the p53 codon 72 Arg/Pro polymorphism is a risk factor for lung cancer in the Asian population. However, the potential role of gene-environment interaction in lung cancer susceptibility needs further investigation in future studies with high quality.

  5. Genome-wide analysis reveals recurrent structural abnormalities of TP63 and other p53-related genes in peripheral T-cell lymphomas

    PubMed Central

    Vasmatzis, George; Johnson, Sarah H.; Knudson, Ryan A.; Ketterling, Rhett P.; Braggio, Esteban; Fonseca, Rafael; Viswanatha, David S.; Law, Mark E.; Kip, N. Sertac; Özsan, Nazan; Grebe, Stefan K.; Frederick, Lori A.; Eckloff, Bruce W.; Thompson, E. Aubrey; Kadin, Marshall E.; Milosevic, Dragana; Porcher, Julie C.; Asmann, Yan W.; Smith, David I.; Kovtun, Irina V.; Ansell, Stephen M.; Dogan, Ahmet

    2012-01-01

    Peripheral T-cell lymphomas (PTCLs) are aggressive malignancies of mature T lymphocytes with 5-year overall survival rates of only ∼ 35%. Improvement in outcomes has been stymied by poor understanding of the genetics and molecular pathogenesis of PTCL, with a resulting paucity of molecular targets for therapy. We developed bioinformatic tools to identify chromosomal rearrangements using genome-wide, next-generation sequencing analysis of mate-pair DNA libraries and applied these tools to 16 PTCL patient tissue samples and 6 PTCL cell lines. Thirteen recurrent abnormalities were identified, of which 5 involved p53-related genes (TP53, TP63, CDKN2A, WWOX, and ANKRD11). Among these abnormalities were novel TP63 rearrangements encoding fusion proteins homologous to ΔNp63, a dominant-negative p63 isoform that inhibits the p53 pathway. TP63 rearrangements were seen in 11 (5.8%) of 190 PTCLs and were associated with inferior overall survival; they also were detected in 2 (1.2%) of 164 diffuse large B-cell lymphomas. As TP53 mutations are rare in PTCL compared with other malignancies, our findings suggest that a constellation of alternate genetic abnormalities may contribute to disruption of p53-associated tumor suppressor function in PTCL. PMID:22855598

  6. Evaluation of p53 protein expression as a marker for long-term prognosis in colorectal carcinoma.

    PubMed Central

    Mulder, J. W.; Baas, I. O.; Polak, M. M.; Goodman, S. N.; Offerhaus, G. J.

    1995-01-01

    Mutation of the p53 gene is reported to be of prognostic importance in colorectal carcinomas. Immunohistochemical staining of the accumulated p53 gene product may be a simple alternative for p53 mutation analysis. Previous studies addressing the prognostic importance of p53 expression, however, yielded contradictory results. Therefore, we evaluated the importance of p53 expression as a marker for long-term prognosis in a well-characterised study population of 109 colorectal carcinomas. After antigen retrieval with target unmasking fluid (TUF), immunostaining of p53 was performed with both monoclonal antibody DO7 and polyclonal antibody CM1. Objective quantification of the p53 signal was assessed by a computerised image analyser. p53 expression was higher in non-mucinous tumours than in mucinous tumours (p53 labelling index = 30% and 17% respectively, P = 0.05), and in metastatic tumours compared with non-metastatic tumours (p53 labelling index = 37% and 22% respectively, P = 0.05). Other histopathological features were not related to p53 expression. In multivariate analysis, Dukes' stage (P = 0.02) and histological grade (P = 0.05) stood out as independent markers for prognosis. p53 expression was not an independent marker for prognosis. At present, p53 expression is not a useful marker for long-term prognosis. Further insight into the relationship between p53 mutations and p53 expression is needed to elucidate more precisely the clinical relevance of p53 alterations. PMID:7779721

  7. Method for lipidomic analysis: p53 expression modulation of sulfatide, ganglioside, and phospholipid composition of U87 MG glioblastoma cells.

    PubMed

    He, Huan; Conrad, Charles A; Nilsson, Carol L; Ji, Yongjie; Schaub, Tanner M; Marshall, Alan G; Emmett, Mark R

    2007-11-15

    Lipidomics can complement genomics and proteomics by providing new insight into dynamic changes in biomembranes; however, few reports in the literature have explored, on an organism-wide scale, the functional link between nonenzymatic proteins and cellular lipids. Here, we report changes induced by adenovirus-delivered wild-type p53 gene and chemotherapy of U87 MG glioblastoma cells, a treatment known to trigger apoptosis and cell cycle arrest. We compare polar lipid changes in treated cells and control cells by use of a novel, sensitive method that employs lipid extraction, one-step liquid chromatography separation, high-resolution mass analysis, and Kendrick mass defect analysis. Nano-LC FT-ICR MS and quadrupole linear ion trap MS/MS analysis of polar lipids yields hundreds of unique assignments of glyco- and phospholipids at sub-ppm mass accuracy and high resolving power (m/Deltam50% = 200 000 at m/z 400) at 1 s/scan. MS/MS data confirm molecular structures in many instances. Sulfatides are most highly modulated by wild-type p53 treatment. The treatment also leads to an increase in phospholipids such as phosphatidyl inositols, phosphatidyl serines, phosphatidyl glycerols, and phosphatidyl ethanolamines. An increase in hydroxylated phospholipids is especially noteworthy. Also, a decrease in the longer chain gangliosides, GD1 and GM1b, is observed in wild-type p53 (treated) cells.

  8. Nobiletin induces apoptosis and potentiates the effects of the anticancer drug 5-fluorouracil in p53-mutated SNU-16 human gastric cancer cells.

    PubMed

    Moon, Jeong Yong; Cho, Moonjae; Ahn, Kwang Seok; Cho, Somi Kim

    2013-01-01

    Nobiletin is a typical polymethoxyl flavone from citrus fruits that has anticancer properties, but the molecular mechanism of its inhibitory effects on the growth of p53-mutated SNU-16 human gastric cancer cells has not been explored. In this study, nobiletin was found to be effective at inhibiting the proliferation of SNU-16 cells than other flavonoids. Nobiletin induced the death of SNU-16 cells through apoptosis, as evidenced by the increased cell population in the sub-G1 phase, the appearance of fragmented nuclei, an increase in the Bax/Bcl-2 ratio, the proteolytic activation of caspase-9, an increase in caspase-3 activity, and the degradation of poly(ADP-ribose) polymerase (PARP) protein. We found that the combination of nobiletin plus the anticancer drug 5-fluorouracil (5-FU) reduced the viability of SNU-16 cells in a concentration-dependent manner and exhibited a synergistic anticancer effect (combination index = 0.38) when 5-FU was used at relatively low concentrations. The expression of p53 protein increased after treatment with 5-FU, but not nobiletin, whereas the expression of p21 (WAF1/CIP1) protein increased after treatment with nobiletin, but not 5-FU. The cellular responses to nobiletin and 5-FU occurred through different pathways. The results of this study suggest the potential application of nobiletin to the enhancement of 5-FU efficiency in p53 mutant tumors.

  9. Ki-67, p53, and p16 expression, and G691S RET polymorphism in desmoplastic melanoma (DM): A clinicopathologic analysis of predictors of outcome.

    PubMed

    Lawrence, Nicholas F; Hammond, Marc R; Frederick, Dennie T; Su, Yuhua; Dias-Santagata, Dora; Deng, April; Selim, M Angelica; Mahalingam, Meera; Flaherty, Keith T; Hoang, Mai P

    2016-09-01

    The prognostic role Ki-67, p53, and p16 immunostains and RET (rearranged during transfection) polymorphism in desmoplastic melanoma has not been evaluated. We sought to identify potential prognostic markers. We performed Ki-67, p53, and p16 immunostains on 66 desmoplastic melanomas, and sequenced RET G691 polymorphism and recurrent mutations of 17 cancer genes in 55 and 20 cases, respectively. Recurrence and metastasis were documented in 11 of 66 (17%) and 26 of 66 (39%) patients, respectively. Death was noted in 25 of 55 (45%) patients. Ki-67 expression (≥10%, 43%) correlated with male gender (P = .009), ulceration (P = .002), and Breslow depth (P = .009). p53 Expression (≥50%, 28%) correlated with male gender (P = .002) and head and neck location (P = .0228). Using Kaplan-Meier plots, Ki-67 expression (P = .0425) and mitosis (P = .00295) correlated with overall survival, whereas vascular invasion (P = .0292) correlated with disease progression. There was a significant correlation between Ki-67 and p53 expression (P = .003). RET polymorphism was present in 10 of 46 (22%) cases and inversely correlated with Breslow depth (P = .024). Our study is small and lacks power to perform a multivariate analysis. Although Ki-67 expression correlated with overall survival, additional studies are needed to determine whether Ki-67 would be an independent prognostic marker in addition to the current routine histopathologic assessment. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  10. Functional analysis of the ATM-p53-p21 pathway in the LRF CLL4 trial: blockade at the level of p21 is associated with short response duration.

    PubMed

    Lin, Ke; Adamson, Janet; Johnson, Gillian G; Carter, Anthony; Oates, Melanie; Wade, Rachel; Richards, Sue; Gonzalez, David; Matutes, Estella; Dearden, Claire; Oscier, David G; Catovsky, Daniel; Pettitt, Andrew R

    2012-08-01

    This study sought to establish whether functional analysis of the ATM-p53-p21 pathway adds to the information provided by currently available prognostic factors in patients with chronic lymphocytic leukemia (CLL) requiring frontline chemotherapy. Cryopreserved blood mononuclear cells from 278 patients entering the LRF CLL4 trial comparing chlorambucil, fludarabine, and fludarabine plus cyclophosphamide were analyzed for ATM-p53-p21 pathway defects using an ex vivo functional assay that uses ionizing radiation to activate ATM and flow cytometry to measure upregulation of p53 and p21 proteins. Clinical endpoints were compared between groups of patients defined by their pathway status. ATM-p53-p21 pathway defects of four different types (A, B, C, and D) were identified in 194 of 278 (70%) samples. The type A defect (high constitutive p53 expression combined with impaired p21 upregulation) and the type C defect (impaired p21 upregulation despite an intact p53 response) were each associated with short progression-free survival. The type A defect was associated with chemoresistance, whereas the type C defect was associated with early relapse. As expected, the type A defect was strongly associated with TP53 deletion/mutation. In contrast, the type C defect was not associated with any of the other prognostic factors examined, including TP53/ATM deletion, TP53 mutation, and IGHV mutational status. Detection of the type C defect added to the prognostic information provided by TP53/ATM deletion, TP53 mutation, and IGHV status. Our findings implicate blockade of the ATM-p53-p21 pathway at the level of p21 as a hitherto unrecognized determinant of early disease recurrence following successful cytoreduction.

  11. The p53 gene and protein in human brain tumors

    SciTech Connect

    Louis, D.N. )

    1994-01-01

    Because p53 gene alterations are commonplace in human tumors and because p53 protein is involved in a number of important cellular pathways, p53 has become a topic of intensive investigation, both by basic scientists and clinicians. p53 was initially identified by two independent laboratories in 1979 as a 53 kilodalton (kD) protein that complexes with the large T antigen of SV40 virus. Shortly thereafter, it was shown that the E1B oncoprotein of adenovirus also binds p53. The binding of two different oncogenic viral tumor proteins to the same cellular protein suggested that p53 might be integral to tumorigenesis. The human p53 cDNA and gene were subsequently cloned in the mid-1980s, and analysis of p53 gene alterations in human tumors followed a few year later. During these 10 years, researchers grappling with the vagaries of p53 first characterized the gene as an oncogene, then as a tumor suppressor gene, and most recently as both a tumor suppressor gene and a so-called [open quotes]dominant negative[close quotes] oncogene. The last few years have seen an explosion in work on this single gene and its protein product. A review of a computerized medical database revealed approximately 650 articles on p53 in 1992 alone. p53 has assumed importance in neuro-oncology because p53 mutations and protein alterations are frequent in the common diffuse, fibrillary astrocytic tumors of adults. p53 mutations in astrocytomas were first described in 1989 and were followed by more extensive analyses of gene mutations and protein alterations in adult astrocytomas. The gene has also been studied in less common brain tumors. Elucidating the role of p53 in brain tumorigenesis will not only enhance understanding of brain tumor biology but may also contribute to improved diagnosis and therapy. This discussion reviews key aspects of the p53 gene and protein, and describe their emerging roles in central nervous system neoplasia. 102 refs., 6 figs., 1 tab.

  12. A computational analysis of binding modes and conformation changes of MDM2 induced by p53 and inhibitor bindings

    NASA Astrophysics Data System (ADS)

    Chen, Jianzhong; Wang, Jinan; Zhu, Weiliang; Li, Guohui

    2013-11-01

    Molecular dynamics (MD) simulations followed by principal component analysis were performed to study the conformational change of MDM2 induced by p53 and two inhibitor (P4 and MI63a) bindings. The results show that the hydrophobic cleft of MDM2 is very flexible and adaptive to different structural binding partners. The cleft tends to become wider and more stable as MDM2 binds to the three binding partners, while unbound MDM2 shows a narrower and pretty flexible cleft, which agrees with recent experimental data and theoretical studies. It was also found that the binding of P4 and p53 stabilizes the motion of the loop L2 linking the helix α2 and β strand (β3), but the presence of MI63a makes the motion of L2 disordered. In addition, the binding free energies of the three partners to MDM2 were calculated using molecular mechanics generalized Born surface area to explain the binding modes of these three partners to MDM2. This study will be helpful not only for better understanding the functional, concerted motion of MDM2, but also for the rational design of potent anticancer drugs targeting the p53-MDM2 interaction.

  13. Assessment of mutations of Ha- and Ki-ras oncogenes and the p53 suppressor gene in seven malignant mesothelioma patients exposed to asbestos--PCR-SSCP and sequencing analyses of paraffin-embedded primary tumors.

    PubMed

    Kitamura, F; Araki, S; Tanigawa, T; Miura, H; Akabane, H; Iwasaki, R

    1998-01-01

    To examine whether malignant mesothelioma due to asbestos has genetic alterations in the Ha- and Ki-ras oncogenes or in the p53 suppressor gene, we analyzed the point mutations of these genes in paraffin-embedded autopsy samples of the primary tumors of malignant mesothelioma in seven asbestos patients who died from malignant mesothelioma. The genetic analysis was conducted by the polymerase chain reaction-single strand comformation polymorphysms (PCR-SSCP) method in all patients, and through the sequencing of deoxyribonucleic acid (DNA) bases in one patient. No genetic alterations were found in exons 1 or 2 of Ha- and Ki-ras oncogenes, or in exons 5 to 9 of the p53 gene, in any of the patients. Further studies on a larger number of patients are required to reach a definite conclusion concerning the genetic effects of asbestos on malignant mesothelioma.

  14. FGFR3b Extracellular Loop Mutation Lacks Tumorigenicity In Vivo but Collaborates with p53/pRB Deficiency to Induce High-grade Papillary Urothelial Carcinoma

    PubMed Central

    Zhou, Haiping; He, Feng; Mendelsohn, Cathy L.; Tang, Moon-shong; Huang, Chuanshu; Wu, Xue-Ru

    2016-01-01

    Missense mutations of fibroblast growth factor receptor 3 (FGFR3) occur in up to 80% of low-grade papillary urothelial carcinoma of the bladder (LGP-UCB) suggesting that these mutations are tumor drivers, although direct experimental evidence is lacking. Here we show that forced expression of FGFR3b-S249C, the most prevalent FGFR3 mutation in human LGP-UCB, in cultured urothelial cells resulted in slightly reduced surface translocation than wild-type FGFR3b, but nearly twice as much proliferation. When we expressed a mouse equivalent of this mutant (FGFR3b-S243C) in urothelia of adult transgenic mice in a tissue-specific and inducible manner, we observed significant activation of AKT and MAPK pathways. This was, however, not accompanied by urothelial proliferation or tumorigenesis over 12 months, due to compensatory tumor barriers in p16-pRB and p19-p53-p21 axes. Indeed, expressing FGFR3b-S249C in cultured human urothelial cells expressing SV40T, which functionally inactivates pRB/p53, markedly accelerated proliferation and cell-cycle progression. Furthermore, expressing FGFR3b-S243C in transgenic mouse urothelium expressing SV40T converted carcinoma-in-situ to high-grade papillary urothelial carcinoma. Together, our study provides new experimental evidence indicating that the FGFR3 mutations have very limited urothelial tumorigenicity and that these mutations must collaborate with other genetic events to drive urothelial tumorigenesis. PMID:27157475

  15. Prevalence of aflatoxin induced p53 mutation at codon 249 (R249s) in hepatocellular carcinoma patients with and without hepatitis B surface antigen (HBsAg).

    PubMed

    Chittmittrapap, Salyavit; Chieochansin, Thaweesak; Chaiteerakij, Roongruedee; Treeprasertsuk, Sombat; Klaikaew, Naruemon; Tangkijvanich, Pisit; Komolmit, Piyawat; Poovorawan, Yong

    2013-01-01

    A missense mutation in exon 7 (R249S) of the p53 tumor suppressor gene is characteristic of aflatoxin B1 (AFB1) exposure. AFB1 is believed to have a synergistic effect on hepatitis virus B (HBV) carcinogenesis. However, results of studies comparing R249S prevalence among patients are conflicting. The aim of this study was to determine the prevalence of the R249S mutation in hepatocellular carcinoma (HCC) patients with or without positive HBsAg. Paraffin embedded liver tissues were obtained from 124 HCC patients who underwent liver resection and liver biopsy in King Chulalongkorn Memorial Hospital. Restriction fragment length polymorphism (RFLP) was utilized to detect the R249S mutation. Positive results were confirmed by direct sequencing. Sixty four (52%) patients were positive for HBsAg and 18 (15%) were anti-HCV positive. 12 specimens tested positive by RFLP. Ten HCC patients (8.1%) were confirmed to be R249S positive by Sanger sequencing (AGG to AGT). Out of these 10, six were HBsAg positive, and out of the remaining 4, two were anti-HCV positive. The R249S prevalence among HCC patients with positive HBsAg was 9.4% compared to 6.7% for HBsAg negative samples. Patients with the R249S mutation were younger (55±10 vs 60±13 year-old) and tended to have a more advanced Edmonson-Steiner grade of HCC, although differences did not reach statistical significance. Our study shows moderate prevalence of aflatoxin B1-related p53 mutation (R249S) in HCC with or without HBsAg. HBsAg positive status was not associated with R249S prevalence.

  16. Association of p53 codon72 Arg>Pro polymorphism with susceptibility to nasopharyngeal carcinoma: evidence from a case–control study and meta-analysis

    PubMed Central

    Sahu, S K; Chakrabarti, S; Roy, S D; Baishya, N; Reddy, R R; Suklabaidya, S; Kumar, A; Mohanty, S; Maji, S; Suryanwanshi, A; Rajasubramaniam, S; Asthana, M; Panda, A K; Singh, S P; Ganguly, S; Shaw, O P; Bichhwalia, A K; Sahoo, P K; Chattopadhyay, N R; Chatterjee, K; Kundu, C N; Das, A K; Kannan, R; Zorenpuii; Zomawia, E; Sema, S A; Singh, Y I; Ghosh, S K; Sharma, K; Das, B S; Choudhuri, T

    2016-01-01

    Tumor suppressor p53 is a critical player in the fight against cancer as it controls the cell cycle check point, apoptotic pathways and genomic stability. It is known to be the most frequently mutated gene in a wide variety of human cancers. Single-nucleotide polymorphism of p53 at codon72 leading to substitution of proline (Pro) in place of arginine (Arg) has been identified as a risk factor for development of many cancers, including nasopharyngeal carcinoma (NPC). However, the association of this polymorphism with NPC across the published literature has shown conflicting results. We aimed to conduct a case–control study for a possible relation of p53 codon72 Arg>Pro polymorphism with NPC risk in underdeveloped states of India, combine the result with previously available records from different databases and perform a meta-analysis to draw a more definitive conclusion. A total of 70 NPC patients and 70 healthy controls were enrolled from different hospitals of north-eastern India. The p53 codon72 Arg>Pro polymorphism was typed by polymerase chain reaction, which showed an association with NPC risk. In the meta-analysis consisting of 1842 cases and 2330 controls, it was found that individuals carrying the Pro allele and the ProPro genotype were at a significantly higher risk for NPC as compared with those with the Arg allele and the ArgArg genotype, respectively. Individuals with a ProPro genotype and a combined Pro genotype (ProPro+ArgPro) also showed a significantly higher risk for NPC over a wild homozygote ArgArg genotype. Additionally, the strength of each study was tested by power analysis and genotype distribution by Hardy–Weinberg equilibrium. The outcome of the study indicated that both allele frequency and genotype distribution of p53 codon72 Arg>Pro polymorphism were significantly associated with NPC risk. Stratified analyses based on ethnicity and source of samples supported the above result. PMID:27159678

  17. p53 and MDM2 in Renal Cell Carcinoma

    PubMed Central

    Noon, Aidan P.; Vlatković, Nikolina; Polański, Radosław; Maguire, Maria; Shawki, Howida; Parsons, Keith; Boyd, Mark T.

    2010-01-01

    Renal cell carcinoma (RCC) is the most common type of kidney cancer and follows an unpredictable disease course. To improve prognostication, a better understanding of critical genes associated with disease progression is required. The objective of this review was to focus attention on 2 such genes, p53 and murine double minute 2 (MDM2), and to provide a comprehensive summary and critical analysis of the literature regarding these genes in RCC. Information was compiled by searching the PubMed database for articles that were published or e-published up to April 1, 2009. Search terms included renal cancer, renal cell carcinoma, p53, and MDM2. Full articles and any supplementary data were examined; and, when appropriate, references were checked for additional material. All studies that described assessment of p53 and/or MDM2 in renal cancer were included. The authors concluded that increased p53 expression, but not p53 mutation, is associated with reduced overall survival/more rapid disease progression in RCC. There also was evidence that MDM2 up-regulation is associated with decreased disease-specific survival. Two features of RCC stood out as unusual and will require further investigation. First, increased p53 expression is tightly linked with increased MDM2 expression; and, second, patients who have tumors that display increased p53 and MDM2 expression may have the poorest overall survival. Because there was no evidence to support the conclusion that p53 mutation is associated with poorer survival, it seemed clear that increased p53 expression in RCC occurs independent of mutation. Further investigation of the mechanisms leading to increased p53/MDM2 expression in RCC may lead to improved prognostication and to the identification of novel therapeutic interventions. PMID:20052733

  18. Energetic Landscape of MDM2-p53 Interactions by Computational Mutagenesis of the MDM2-p53 Interaction.

    PubMed

    Thayer, Kelly M; Beyer, George A

    2016-01-01

    The ubiquitin ligase MDM2, a principle regulator of the tumor suppressor p53, plays an integral role in regulating cellular levels of p53 and thus a prominent role in current cancer research. Computational analysis used MUMBO to rotamerize the MDM2-p53 crystal structure 1YCR to obtain an exhaustive search of point mutations, resulting in the calculation of the ΔΔG comprehensive energy landscape for the p53-bound regulator. The results herein have revealed a set of residues R65-E69 on MDM2 proximal to the p53 hydrophobic binding pocket that exhibited an energetic profile deviating significantly from similar residues elsewhere in the protein. In light of the continued search for novel competitive inhibitors for MDM2, we discuss possible implications of our findings on the drug discovery field.

  19. Slow repair of lipid peroxidation-induced DNA damage at p53 mutation hotspots in human cells caused by low turnover of a DNA glycosylase

    PubMed Central

    Woodrick, Jordan; Gupta, Suhani; Khatkar, Pooja; Sarangi, Sanchita; Narasimhan, Ganga; Trehan, Akriti; Adhikari, Sanjay; Roy, Rabindra

    2014-01-01

    Repair of oxidative stress- and inflammation-induced DNA lesions by the base excision repair (BER) pathway prevents mutation, a form of genomic instability which is often observed in cancer as ‘mutation hotspots’. This suggests that some sequences have inherent mutability, possibly due to sequence-related differences in repair. This study has explored intrinsic mutability as a consequence of sequence-specific repair of lipid peroxidation-induced DNA adduct, 1, N6-ethenoadenine (εA). For the first time, we observed significant delay in repair of ϵA at mutation hotspots in the tumor suppressor gene p53 compared to non-hotspots in live human hepatocytes and endothelial cells using an in-cell real time PCR-based method. In-cell and in vitro mechanism studies revealed that this delay in repair was due to inefficient turnover of N-methylpurine-DNA glycosylase (MPG), which initiates BER of εA. We determined that the product dissociation rate of MPG at the hotspot codons was ≈5–12-fold lower than the non-hotspots, suggesting a previously unknown mechanism for slower repair at mutation hotspots and implicating sequence-related variability of DNA repair efficiency to be responsible for mutation hotspot signatures. PMID:25081213

  20. The APE1 Asp/Asp genotype and the combination of APE1 Asp/Asp and hOGG1-Cys variants are associated with increased p53 mutation in non-small cell lung cancer.

    PubMed

    Lin, Chun-Hsuan; Chen, Po-Ming; Cheng, Ya-Wen; Chen, Chih-Yi; Yuan, Chiun-Jye; Lee, Huei

    2012-01-01

    The hOGG1 Ser326Cys polymorphism is associated with lung cancer risk, but there are limited data regarding an association between the APE1 Asp148Glu polymorphism and lung cancer. Biological evidence shows that the hOGG1-Cys allele results in less DNA repair activity; however, this is not associated with p53 mutation in lung cancer. Therefore, we investigated whether an interaction between hOGG1 and APE1 is associated with the frequency of p53 mutation in lung cancer. We studied 217 Taiwanese adults with primary lung cancer. DNA polymorphisms of hOGG1 and APE1 were determined by polymerase chain reaction (PCR)-based restriction fragment length polymorphism. Mutations in p53 exons 5-8 were detected by direct sequencing. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% CIs for the risk of p53 mutation associated with polymorphisms of hOGG1 and APE1 in lung cancer. As expected, no association between hOGG1 polymorphism and p53 mutation was observed in this population. However, a higher risk of p53 mutation was found in participants with the APE1 Asp/Asp genotype than in those with the APE1-Glu allele (OR, 2.15; 95% CI, 1.19-3.87; P = 0.011). The risk of p53 mutation was also higher in participants with APE1 Asp/Asp plus hOGG1-Cys than in those with APE1-Glu plus hOGG1 Ser/Ser (OR, 3.72; 95% CI, 1.33-10.40; P = 0.012). These results suggest that the APE1 Asp/Asp genotype and the combination of the APE1 Asp/Asp and hOGG1-Cys variants are associated with increased risk of p53 mutation in non-small cell lung cancer.

  1. Genome-wide analysis of the human p53 transcriptional network unveils a lncRNA tumour suppressor signature.

    PubMed

    Sánchez, Yolanda; Segura, Victor; Marín-Béjar, Oskar; Athie, Alejandro; Marchese, Francesco P; González, Jovanna; Bujanda, Luis; Guo, Shuling; Matheu, Ander; Huarte, Maite

    2014-12-19

    Despite the inarguable relevance of p53 in cancer, genome-wide studies relating endogenous p53 activity to the expression of lncRNAs in human cells are still missing. Here, by integrating RNA-seq with p53 ChIP-seq analyses of a human cancer cell line under DNA damage, we define a high-confidence set of 18 lncRNAs that are p53 transcriptional targets. We demonstrate that two of the p53-regulated lncRNAs are required for the efficient binding of p53 to some of its target genes, modulating the p53 transcriptional network and contributing to apoptosis induction by DNA damage. We also show that the expression of p53-lncRNAs is lowered in colorectal cancer samples, constituting a tumour suppressor signature with high diagnostic power. Thus, p53-regulated lncRNAs establish a positive regulatory feedback loop that enhances p53 tumour suppressor activity. Furthermore, the signature defined by p53-regulated lncRNAs supports their potential use in the clinic as biomarkers and therapeutic targets.

  2. SAGE analysis highlights the importance of p53csv, ddx5, mapkapk2 and ranbp2 to multiple myeloma tumorigenesis.

    PubMed

    Felix, Roberta S; Colleoni, Gisele W B; Caballero, Otavia L; Yamamoto, Mihoko; Almeida, Manuella S S; Andrade, Valéria C C; Chauffaille, Maria de Lourdes L F; Silva, Wilson A da; Begnami, Maria Dirlei; Soares, Fernando Augusto; Simpson, Andrew J; Zago, Marco Antonio; Vettore, André L

    2009-06-08

    Serial analysis of gene expression (SAGE) allows a comprehensive profiling of gene expression within a given tissue and also an assessment of transcript abundance. We generated SAGE libraries from normal and neoplastic plasma cells to identify genes differentially expressed in multiple myeloma (MM). Normal plasma cells were obtained from palatine tonsils and MM SAGE library was generated from bone marrow plasma cells of MM patients. We obtained 29,918 SAGE tags from normal and 10,340 tags from tumor libraries. Computer-generated genomic analysis identified 46 upregulated genes in the MM library. Ten upregulated genes were selected for further investigation. Differential expression was validated by quantitative real-time PCR in purified plasma cells of 31 patients and three controls. P53CSV, DDX5, MAPKAPK2 and RANBP2 were found to be upregulated in at least 50% of the MM cases tested. All of them were also found upregulated in MM when compared to normal plasma cells in a meta-analysis using ONCOMINE microarray database. Antibodies specific to DDX5, RANBP2 and MAPKAPK2 were used in a TMA containing 57 MM cases and confirmed the expression of these proteins in 74%, 96%, and 21% of the MM samples, respectively. Analysis of differential expression using SAGE could identify genes important for myeloma tumorigenesis (P53CSV, DDX5, MAPKPK2 and RANBP2) and that could potentially be useful as therapeutic targets.

  3. Autoantibody recognition mechanisms of p53 epitopes

    NASA Astrophysics Data System (ADS)

    Phillips, J. C.

    2016-06-01

    There is an urgent need for economical blood based, noninvasive molecular biomarkers to assist in the detection and diagnosis of cancers in a cost-effective manner at an early stage, when curative interventions are still possible. Serum autoantibodies are attractive biomarkers for early cancer detection, but their development has been hindered by the punctuated genetic nature of the ten million known cancer mutations. A landmark study of 50,000 patients (Pedersen et al., 2013) showed that a few p53 15-mer epitopes are much more sensitive colon cancer biomarkers than p53, which in turn is a more sensitive cancer biomarker than any other protein. The function of p53 as a nearly universal "tumor suppressor" is well established, because of its strong immunogenicity in terms of not only antibody recruitment, but also stimulation of autoantibodies. Here we examine dimensionally compressed bioinformatic fractal scaling analysis for identifying the few sensitive epitopes from the p53 amino acid sequence, and show how it could be used for early cancer detection (ECD). We trim 15-mers to 7-mers, and identify specific 7-mers from other species that could be more sensitive to aggressive human cancers, such as liver cancer. Our results could provide a roadmap for ECD.

  4. Latex bead immobilisation in PDMS matrix for the detection of p53 gene point mutation and anti-HIV-1 capsid protein antibodies.

    PubMed

    Marquette, Christophe A; Degiuli, Agnès; Imbert-Laurenceau, Emmanuelle; Mallet, Francois; Chaix, Carole; Mandrand, Bernard; Blum, Loïc J

    2005-03-01

    Two diagnostic chemiluminescent biochips were developed for either the detection of p53 gene point mutation or the serological detection of anti-HIV-1 p24 capsid protein. Both biochips were composed of 24 microarrays of latex beads spots (4x4) (150 microm in diameter, 800 microm spacing) entrapped in a poly(dimethylsiloxane) elastomer (PDMS). The latex beads, bearing oligonucleotide sequences or capsid protein, were spotted with a conventional piezoelectric spotter and subsequently transferred at the PDMS interface. The electron microscopy observation of the biochips showed how homogeneous and well distributed the spots could be. Point mutation detection on the codon 273 of the p53 gene was performed on the basis of the melting temperature difference between the perfect match sequence and the one base pair mismatch sequence. The hybridisation of a 20-mer oligonucleotide form the codon 273 including a one base pair mutation in its sequence on a biochip arrayed with non-muted and the muted complementary sequences, enabled a clear discrimination at 56 degrees C between muted and wild sequences. Moreover, the quantitative measurement of the amount of muted sequence in a sample was possible in the range 0.4-4 pmol. Serological measurement of anti-HIV-1 p24 capsid protein on the biochip, prepared with 1-microm-diameter latex beads, enabled the detection of monoclonal antibodies in the range 1.55-775 ng mL(-1). Such a range could be lowered to 0.775 ng mL(-1) when using 50-nm-diameter beads, which generated a higher specific surface. The validation of the biochip for the detection of anti-HIV-1 capsid protein antibodies was performed in human sera from seropositive and seronegative patients. The positivity of the sera was easily discriminated at serum dilutions below 1:1,000.

  5. Towards MIB-1 and p53 detection in glioma magnetic resonance image: a novel computational image analysis method.

    PubMed

    Liu, Chenbin; Zhang, Haishi; Pan, Ying; Huang, Fengping; Xia, Shunren

    2012-12-21

    Glioma is the primary tumor in the central nervous system, and poses one of the greatest challenges in clinical treatment. MIB-1 and p53 are the most useful biomarkers for gliomas and could help neurosurgeons establish a therapeutic schedule. However, these biomarkers are commonly detected with the help of immunohistochemistry (IHC), which wastes time and energy and is often influenced by subjective factors. To reduce the subjective factors and improve the efficiency in the judgment of IHC, a novel magnetic resonance image (MRI) analysis method is proposed in the present study to detect the expression status of MIB-1 and p53 in IHC. The proposed method includes two kinds of MRI acquisition (FLAIR and T1 FLAIR images), regions of interest (ROIs) selection, texture features (i.e. the gray level gradient co-occurrence matrix (GLGCM), Minkowski functions (MFs), etc) extraction in ROIs, and classification with a support vector machine in a leave-one-out cross validation strategy. By classifying the ROIs, the performance of the method was evaluated by accuracy, area under ROC curve (AUC), etc. A high accuracy (0.7640 ± 0.0225) and AUC (0.7873 ± 0.0377) for MIB-I detection were achieved. In terms of the texture features, 0.7621 ± 0.0199, 0.7666 ± 0.0365 and 0.7426 ± 0.0451 AUC can be obtained using only GLCM, RLM or GLGCM for MIB-1 detection, respectively. In all, the experimental results demonstrated that MR image texture features are associated with the expression status of MIB-1 and p53. The proposed method has the potential to realize high accuracy and robust detection for MIB-I expression status, which makes it promising for clinical glioma diagnosis and prognosis.

  6. Towards MIB-1 and p53 detection in glioma magnetic resonance image: a novel computational image analysis method

    NASA Astrophysics Data System (ADS)

    Liu, Chenbin; Zhang, Haishi; Pan, Ying; Huang, Fengping; Xia, Shunren

    2012-12-01

    Glioma is the primary tumor in the central nervous system, and poses one of the greatest challenges in clinical treatment. MIB-1 and p53 are the most useful biomarkers for gliomas and could help neurosurgeons establish a therapeutic schedule. However, these biomarkers are commonly detected with the help of immunohistochemistry (IHC), which wastes time and energy and is often influenced by subjective factors. To reduce the subjective factors and improve the efficiency in the judgment of IHC, a novel magnetic resonance image (MRI) analysis method is proposed in the present study to detect the expression status of MIB-1 and p53 in IHC. The proposed method includes two kinds of MRI acquisition (FLAIR and T1 FLAIR images), regions of interest (ROIs) selection, texture features (i.e. the gray level gradient co-occurrence matrix (GLGCM), Minkowski functions (MFs), etc) extraction in ROIs, and classification with a support vector machine in a leave-one-out cross validation strategy. By classifying the ROIs, the performance of the method was evaluated by accuracy, area under ROC curve (AUC), etc. A high accuracy (0.7640 ± 0.0225) and AUC (0.7873 ± 0.0377) for MIB-I detection were achieved. In terms of the texture features, 0.7621 ± 0.0199, 0.7666 ± 0.0365 and 0.7426 ± 0.0451 AUC can be obtained using only GLCM, RLM or GLGCM for MIB-1 detection, respectively. In all, the experimental results demonstrated that MR image texture features are associated with the expression status of MIB-1 and p53. The proposed method has the potential to realize high accuracy and robust detection for MIB-I expression status, which makes it promising for clinical glioma diagnosis and prognosis.

  7. Expression pattern of ataxia telangiectasia mutated (ATM), p53, Akt, and glycogen synthase kinase-3β in the striatum of rats treated with 3-nitropropionic acid.

    PubMed

    Duran-Vilaregut, Joaquim; Manich, Gemma; Del Valle, Jaume; Camins, Antoni; Pallàs, Mercè; Vilaplana, Jordi; Pelegrí, Carme

    2012-09-01

    3-Nitropropionic acid (3-NPA) is a mitochondrial toxin used in the laboratory to replicate neurodegenerative conditions that are accompanied by degeneration of the caudate-putamen. 3-NPA induces depletion in ATP production, reactive oxygen species production, and secondary excitotoxicity mediated by activation of N-methyl-D-aspartate receptors that culminates in the triggering of cell death mechanisms, including apoptosis. We here examined by immunohistochemical methods whether cellular expression of phospho(Ser1981) -ataxia telangiectasia mutated (ATM), phospho(Ser15) -p53, phospho(Ser473) -Akt, and phospho(Ser9) -glycogen synthase kinase-3β (GSK3β), which are key signal molecules that play a critical role in regulating cellular processes related to cell survival and demise, were involved in the striatal neurodegeneration in the brains of rats treated with 3-NPA. Our results indicate that the toxin induced the activation of ATM and p53 only in astrocytes, and a role for these proteins in neuronal degeneration was ruled out. On the other hand, striatal neurons lost the active form of Akt as soon as they began to appear pyknotic, indicating impairment of the PI3K/Akt/GSK3 pathway in their degenerative process. The inactive form of GSK3β was detected extensively, mainly in the rim of the striatal lesions around degenerating neurons, which could be attributed to a cell death or cell survival response.

  8. Regulation of p53 tetramerization and nuclear export by ARC

    PubMed Central

    Foo, Roger S.-Y.; Nam, Young-Jae; Ostreicher, Marc Jason; Metzl, Mark D.; Whelan, Russell S.; Peng, Chang-Fu; Ashton, Anthony W.; Fu, Weimin; Mani, Kartik; Chin, Suet-Feung; Provenzano, Elena; Ellis, Ian; Figg, Nichola; Pinder, Sarah; Bennett, Martin R.; Caldas, Carlos; Kitsis, Richard N.

    2007-01-01

    Inactivation of the transcription factor p53 is central to carcinogenesis. Yet only approximately one-half of cancers have p53 loss-of-function mutations. Here, we demonstrate a mechanism for p53 inactivation by apoptosis repressor with caspase recruitment domain (ARC), a protein induced in multiple cancer cells. The direct binding in the nucleus of ARC to the p53 tetramerization domain inhibits p53 tetramerization. This exposes a nuclear export signal in p53, triggering Crm1-dependent relocation of p53 to the cytoplasm. Knockdown of endogenous ARC in breast cancer cells results in spontaneous tetramerization of endogenous p53, accumulation of p53 in the nucleus, and activation of endogenous p53 target genes. In primary human breast cancers with nuclear ARC, p53 is almost always WT. Conversely, nearly all breast cancers with mutant p53 lack nuclear ARC. We conclude that nuclear ARC is induced in cancer cells and negatively regulates p53. PMID:18087040

  9. The pattern of p53 mutations caused by PAH o-quinones is driven by 8-oxo-dGuo formation while the spectrum of mutations is determined by biological selection for dominance.

    PubMed

    Park, Jong-Heum; Gelhaus, Stacy; Vedantam, Srilakshmi; Oliva, Andrea L; Batra, Abhita; Blair, Ian A; Troxel, Andrea B; Field, Jeffrey; Penning, Trevor M

    2008-05-01

    PAHs (polycyclic aromatic hydrocarbons) are suspect lung cancer carcinogens that must be metabolically converted into DNA-reactive metabolites. P4501A1/P4501B1 plus epoxide hydrolase activate PAH to (+/-)- anti-benzo[ a]pyrene diol epoxide ((+/-)- anti-BPDE), which causes bulky DNA adducts. Alternatively, aldo-keto reductases (AKRs) convert intermediate PAH trans-dihydrodiols to o-quinones, which cause DNA damage by generating reactive oxygen species (ROS). In lung cancer, the types or pattern of mutations in p53 are predominantly G to T transversions. The locations of these mutations form a distinct spectrum characterized by single point mutations in a number of hotspots located in the DNA binding domain. One route to the G to T transversions is via oxidative DNA damage. An RP-HPLC-ECD assay was used to detect the formation of 8-oxo-dGuo in p53 cDNA exposed to representative quinones, BP-7,8-dione, BA-3,4-dione, and DMBA-3,4-dione under redox cycling conditions. Concurrently, a yeast reporter system was used to detect mutations in the same cDNA samples. Nanomolar concentrations of PAH o-quinones generated 8-oxo-dGuo (detected by HPLC-ECD) in a concentration dependent manner that correlated in a linear fashion with mutagenic frequency. By contrast, micromolar concentrations of (+/-)- anti-BPDE generated (+)- trans- anti-BPDE-N (2)-dGuo adducts (detected by stable-isotope dilution LC/MS methodology) in p53 cDNA that correlated in a linear fashion with mutagenic frequency, but no 8-oxo-dGuo was detected. Previous studies found that mutations observed with PAH o-quinones were predominately G to T transversions and those observed with (+/-)- anti-BPDE were predominately G to C transversions. However, mutations at guanine bases observed with either PAH-treatment occurred randomly throughout the DNA-binding domain of p53. Here, we find that when the mutants were screened for dominance, the dominant mutations clustered at or near hotspots primarily at the protein

  10. p16INK4A, p53, EGFR expression and KRAS mutation status in squamous cell cancers of the anus: correlation with outcomes following chemo-radiotherapy.

    PubMed

    Gilbert, Duncan C; Williams, Anthony; Allan, Kimberley; Stokoe, Joanna; Jackson, Tim; Linsdall, Suzanne; Bailey, Charles Mh; Summers, Jeff

    2013-10-01

    Squamous cell carcinomas of the anal canal are associated with infection with Human Papilloma Viruses (HPVs). Chemo-radiotherapy (CRT) gives 70% 3-year relapse-free survival. Improved predictive markers and therapeutic options are required. Tumours from 153 patients treated with radical chemo-radiotherapy (50.4 Gy in 28# with concurrent Mitomycin and 5-Fluorouracil between 2004 and 2009) were retrieved and immunohistochemistry performed for p16(INK4A), p53 and EGFR and correlated with outcome. Primary and relapsed samples were analysed for mutations in KRAS. 137/153 (89.5%) stained moderately or strongly for p16(INK4A). p16(INK4A) correlated strongly with outcome. 37/137 patients demonstrating moderate/strong p16(INK4A) expression relapsed (27.0%), as opposed to 10/16 (62.5%) with absent/weak staining (log rank test p<0.001). p16 and p53 expression were inversely correlated. p16(INK4A) negative tumours were more frequent in men. p16(INK4A) negative patients had significantly worse overall survival (p<0.001). No mutations in KRAS were identified in primary tumours or relapses following treatment. p16(INK4A) is strongly associated with relapse in SCC of the anus and identifies patients with very poor rates of relapse-free and overall survival. Primary and recurrent anal cancer expresses wild type KRAS, unaffected by treatment, supporting trials targeting EGFR in poor risk/recurrent anal cancer. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  11. Fractionated radiotherapy is the main stimulus for the induction of cell death and of Hsp70 release of p53 mutated glioblastoma cell lines

    PubMed Central

    2014-01-01

    Background Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. Despite a multimodal therapy consisting of resection followed by fractionated radiotherapy (RT) combined with the chemotherapeutic agent (CT) temozolomide (TMZ), its recurrence is almost inevitable. Since the immune system is capable of eliminating small tumor masses, a therapy should also aim to stimulate anti-tumor immune responses by induction of immunogenic cell death forms. The histone deacetylase inhibitor valproic acid (VPA) might foster this. Methods Reflecting therapy standards, we applied in our in vitro model fractionated RT with a single dose of 2Gy and clinically relevant concentrations of CT. Not only the impact of RT and/or CT with TMZ and/or VPA on the clonogenic potential and cell cycle of the glioblastoma cell lines T98G, U251MG, and U87MG was analyzed, but also the resulting cell death forms and release of danger signals such as heat-shock protein70 (Hsp70) and high-mobility group protein B1 (HMGB1). Results The clonogenic assays revealed that T98G and U251MG, having mutated tumor suppressor protein p53, are more resistant to RT and CT than U87MG with wild type (WT) p53. In all glioblastoma cells lines, fractionated RT induced a G2 cell cycle arrest, but only in the case of U87MG, TMZ and/or VPA alone resulted in this cell cycle block. Further, fractionated RT significantly increased the number of apoptotic and necrotic tumor cells in all three cell lines. However, only in U87MG, the treatment with TMZ and/or VPA alone, or in combination with fractionated RT, induced significantly more cell death compared to untreated or irradiated controls. While necrotic glioblastoma cells were present after VPA, TMZ especially led to significantly increased amounts of U87MG cells in the radiosensitive G2 cell cycle phase. While CT did not impact on the release of Hsp70, fractionated RT resulted in significantly increased extracellular concentrations of Hsp70 in p53

  12. Mutations of p53 and KRAS activate NF-κB to promote chemoresistance and tumorigenesis via dysregulation of cell cycle and suppression of apoptosis in lung cancer cells.

    PubMed

    Yang, Lina; Zhou, Yunjiao; Li, Yinghua; Zhou, Juan; Wu, Yougen; Cui, Yunqing; Yang, Gong; Hong, Yang

    2015-02-28

    Although mutations of p53 and KRAS and activation of NF-κB signaling have been highly associated with chemoresistance and tumorigenesis of lung cancer, the interactive mechanisms between two of p53, KRAS, and NF-κB are elusive. In the present study, we first observed that blocking of NF-κB function in KRAS mutant A549 cell line with an IκBα mutant (IκBαM) inhibited cell cycle progression, anti-apoptosis, chemoresistance, and tumorigenesis. Silencing of p53 or KRAS in A549 or H358 cells either enhanced or attenuated the resistance of cells to cisplatin and taxol through promotion or suppression of the NF-κB p65 nuclear translocation. Introduction of a wild type p53 into p53 null lung cancer cell lines H1299 and H358 inhibited NF-κB activity, leading to the enhanced response to chemotherapeutic drugs. Delivery of a mutant p53 or KRAS-V12 into A549/IκBαM or H1299/p53Wt cells increased cell cycle progression, anti-apoptosis, chemoresistance, and tumorigenesis due to the accumulated nuclear localization of NF-κB p65, while treatment of H1299/p53Wt/KRAS-V12 with NF-κB inhibitor PS1145 diminished these effects. Thus, we conclude that p53 deficiency and KRAS mutation activate the NF-κB signaling to control chemoresistance and tumorigenesis, and that the status of p53 and KRAS may be considered for the targeted therapy against NF-κB in lung cancer patients.

  13. 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.

  14. SCH529074, a small molecule activator of mutant p53, which binds p53 DNA binding domain (DBD), restores growth-suppressive function to mutant p53 and interrupts HDM2-mediated ubiquitination of wild type p53.

    PubMed

    Demma, Mark; Maxwell, Eugene; Ramos, Robert; Liang, Lianzhu; Li, Cheng; Hesk, David; Rossman, Randall; Mallams, Alan; Doll, Ronald; Liu, Ming; Seidel-Dugan, Cynthia; Bishop, W Robert; Dasmahapatra, Bimalendu

    2010-04-02

    Abrogation of p53 function occurs in almost all human cancers, with more than 50% of cancers harboring inactivating mutations in p53 itself. Mutation of p53 is indicative of highly aggressive cancers and poor prognosis. The vast majority of mutations in p53 occur in its core DNA binding domain (DBD) and result in inactivation of p53 by reducing its thermodynamic stability at physiological temperature. Here, we report a small molecule, SCH529074, that binds specifically to the p53 DBD in a saturable manner with an affinity of 1-2 microm. Binding restores wild type function to many oncogenic mutant forms of p53. This small molecule reactivates mutant p53 by acting as a chaperone, in a manner similar to that previously reported for the peptide CDB3. Binding of SCH529074 to the p53 DBD is specifically displaced by an oligonucleotide with a sequence derived from the p53-response element. In addition to reactivating mutant p53, SCH529074 binding inhibits ubiquitination of p53 by HDM2. We have also developed a novel variant of p53 by changing a single amino acid in the core domain of p53 (N268R), which abolishes binding of SCH529074. This amino acid change also inhibits HDM2-mediated ubiquitination of p53. Our novel findings indicate that through its interaction with p53 DBD, SCH529074 restores DNA binding activity to mutant p53 and inhibits HDM2-mediated ubiquitination.

  15. The p53R172H Mutant Does Not Enhance Hepatocellular Carcinoma Development and Progression

    PubMed Central

    Ahronian, Leanne G.; Driscoll, David R.; Klimstra, David S.; Lewis, Brian C.

    2015-01-01

    Hepatocellular carcinoma is a highly deadly malignancy, accounting for approximately 800,000 deaths worldwide every year. Mutation of the p53 tumor suppressor gene is a common genetic change in HCC, present in 30% of cases. p53R175H (corresponding to p53R172H in mice) is a hotspot for mutation that demonstrates “prometastatic” gain-of-function in other cancer models. Since the frequency of p53 mutation increases with tumor grade in HCC, we hypothesized that p53R172H is a gain-of-function mutation in HCC that contributes to a decrease in tumor-free survival and an increase in metastasis. In an HCC mouse model, we found that p53R172H/flox mice do not have decreased survival, increased tumor incidence, or increased metastasis, relative to p53flox/flox littermates. Analysis of cell lines derived from both genotypes indicated that there are no differences in anchorage-independent growth and cell migration. However, shRNA-mediated knockdown of mutant p53 in p53R172H-expressing HCC cell lines resulted in decreased cell migration and anchorage-independent growth. Thus, although p53 mutant-expressing cells and tumors do not have enhanced properties relative to their p53 null counterparts, p53R172H-expressing HCC cells depend on this mutant for their transformation. p53 mutants have been previously shown to bind and inhibit the p53 family proteins p63 and p73. Interestingly, we find that the levels of p63 and p73 target genes are similar in p53 mutant and p53 null HCC cells. These data suggest that pathways regulated by these p53 family members are similarly impacted by p53R172H in mutant expressing cells, and by alternate mechanisms in p53 null cells, resulting in equivalent phenotypes. Consistent with this, we find that p53 null HCC cell lines display lower levels of the TA isoforms of p63 and p73 and higher levels of ΔNp63. Taken together these data point to the importance of p63 and p73 in constraining HCC progression. PMID:25885474

  16. p53 alterations predict tumor response to neoadjuvant chemotherapy in head and neck squamous cell carcinoma: a prospective series.

    PubMed

    Cabelguenne, A; Blons, H; de Waziers, I; Carnot, F; Houllier, A M; Soussi, T; Brasnu, D; Beaune, P; Laccourreye, O; Laurent-Puig, P

    2000-04-01

    The tumor suppressor gene p53 plays a crucial role in cell cycle control and apoptosis in response to DNA damages. p53 gene mutations and allelic losses at 17p are one of the most common genetic alterations in primary head and neck squamous cell carcinoma (HNSCC). Alterations of the p53 gene have been shown to contribute to carcinogenesis and drug resistance. In this prospective series, patients with HNSCC were treated with cisplatin-fluorouracil neoadjuvant chemotherapy. p53 status was characterized in 106 patients with HNSCC (p53 mutations, allelic losses at p53 locus, and plasma anti-p53 antibodies) to determine the existence of a relationship between p53 gene status and response to neoadjuvant chemotherapy. Exons 4 to 9 of the p53 gene were analyzed, and mutations were found in 72 of 106 patients with HNSCC. p53 mutations were associated with loss of heterozygosity at chromosome 17p (P <.001). The prevalence of p53-mutated tumors was higher in the group of patients with nonresponse to neoadjuvant chemotherapy than in the group of responders (81% v 61%, respectively; P <.04). When compiling p53 mutations and anti-p53 antibodies in plasma, the correlation between p53 status and response to chemotherapy was significant (87% v 57%, respectively; P =.003). A multivariate analysis showed that p53 status is an independent predictive factor of response to chemotherapy. This prospective study suggests that p53 status may be a useful indicator of response to neoadjuvant chemotherapy in HNSCC.

  17. Bifurcation analysis and potential landscapes of the p53-Mdm2 module regulated by the co-activator programmed cell death 5.

    PubMed

    Bi, Yuanhong; Yang, Zhuoqin; Zhuge, Changjing; Lei, Jinzhi

    2015-11-01

    The dynamics of p53 play important roles in the regulation of cell fate decisions in response to various stresses, and programmed cell death 5 (PDCD5) functions as a co-activator of p53 that modulates p53 dynamics. In the present paper, we investigated how p53 dynamics are modulated by PDCD5 during the deoxyribose nucleic acid damage response using methods of bifurcation analysis and potential landscape. Our results revealed that p53 activities display rich dynamics under different PDCD5 levels, including monostability, bistability with two stable steady states, oscillations, and the coexistence of a stable steady state (or two states) and an oscillatory state. The physical properties of the p53 oscillations were further demonstrated by the potential landscape in which the potential force attracts the system state to the limit cycle attractor, and the curl flux force drives coherent oscillation along the cyclic trajectory. We also investigated the efficiency with which PDCD5 induced p53 oscillations. We show that Hopf bifurcation can be induced by increasing the PDCD5 efficiency and that the system dynamics exhibited clear transition features in both barrier height and energy dissipation when the efficiency was close to the bifurcation point.

  18. Bifurcation analysis and potential landscapes of the p53-Mdm2 module regulated by the co-activator programmed cell death 5

    NASA Astrophysics Data System (ADS)

    Bi, Yuanhong; Yang, Zhuoqin; Zhuge, Changjing; Lei, Jinzhi

    2015-11-01

    The dynamics of p53 play important roles in the regulation of cell fate decisions in response to various stresses, and programmed cell death 5 (PDCD5) functions as a co-activator of p53 that modulates p53 dynamics. In the present paper, we investigated how p53 dynamics are modulated by PDCD5 during the deoxyribose nucleic acid damage response using methods of bifurcation analysis and potential landscape. Our results revealed that p53 activities display rich dynamics under different PDCD5 levels, including monostability, bistability with two stable steady states, oscillations, and the coexistence of a stable steady state (or two states) and an oscillatory state. The physical properties of the p53 oscillations were further demonstrated by the potential landscape in which the potential force attracts the system state to the limit cycle attractor, and the curl flux force drives coherent oscillation along the cyclic trajectory. We also investigated the efficiency with which PDCD5 induced p53 oscillations. We show that Hopf bifurcation can be induced by increasing the PDCD5 efficiency and that the system dynamics exhibited clear transition features in both barrier height and energy dissipation when the efficiency was close to the bifurcation point.

  19. Quantitative analysis of residual folding and DNA binding in mutant p53 core domain: definition of mutant states for rescue in cancer therapy.

    PubMed

    Bullock, A N; Henckel, J; Fersht, A R

    2000-03-02

    The tumour suppressor p53 is mutated in half of all human cancers, most frequently with missense substitutions in its core domain. We present a new assessment of the mutation database based on quantitative folding and DNA-binding studies of the isolated core domain. Our data identify five distinct mutant classes that correlate with four well-defined regions of the core domain structure. On extrapolation to 37 degrees C the wild-type protein has a stability of 3.0 kcal/mol. This also emerges as an oncogenic threshold: all beta-sandwich mutants destabilized by this amount (50% denatured) are expected to promote cancer. Other weakly destabilizing mutations are restricted to loop 3 in the DNA-binding region. Drugs that stabilize mutant p53 folding have the potential to reactivate apoptotic signalling pathways in tumour cells either by transactivation-dependent or independent pathways. Using an affinity ligand as a proof of principle we have recovered the thermodynamic stability of the hotspot G245S. With reference states for the five mutant classes as a guide, future therapeutic strategies may similarly stabilize partially structured or binding states of mutant p53 that restore limited p53 pathways to tumour suppression.

  20. p53 gene alterations and protein accumulation in colorectal cancer

    PubMed Central

    Bertorelle, R; Esposito, G; Belluco, C; Bonaldi, L; Del Mistro, A; Nitti, D; Lise, M; Chieco-Bianchi, L

    1996-01-01

    Aim—To correlate immunohistochemical staining with single strand conformation polymorphism (SSCP) analysis of the p53 gene in colorectal cancer in order to understand how the findings provided by the two techniques complement each other in defining p53 functional status. Methods—Frozen tumour tissue from 94 patients with colorectal cancer was studied for p53 protein accumulation and gene mutations. Accumulation of p53 protein was detected by immunohistochemistry using PAb1801 and BP53-12-1 monoclonal antibodies. The findings were then compared with SSCP analysis of exons 5 to 8 of the p53 gene. All cases with a positive result by SSCP analysis were confirmed by sequencing. Results—Nuclear staining was observed in 51 (54.2%) cases. SSCP analysis of the DNA amplified by PCR revealed that the electrophoretic pattern had shifted in 30 cases; sequence analysis confirmed the occurrence of a mutation in 29 cases and of a polymorphism in one. In 27 cases both assays gave a positive result, and in 40 both were negative; therefore, concordance between PCR-SSCP and immunohistochemistry was seen in 72% of cases. Conclusion—The data indicate that positive immunostaining corresponds with the presence of a mutation in most, but not all, cases studied; other mechanisms could be responsible for stabilisation and accumulation of p53 protein in the nucleus. Nonsense mutations which do not confer stability on the protein will not be detected by immunohistochemistry and false negative results can also occur with SSCP analysis. Images PMID:16696056

  1. Analysis of the Mechanism of Action of RPF1: Potentiator of Progesterone Receptor and p53-dependent Transcriptional Activity

    DTIC Science & Technology

    2000-07-01

    of the Mechanism of Action of RPFl: Potentiator of Progesterone Receptor and p53-dependent Transcriptional Activity PRINCIPAL INVESTIGATOR: Maria ...this change. Thank you in advance for your help. Sincerely, Maria R. Huacani Principal Investigator DAMD17-98-1-8072 2 Form Approved REPORT...the Mechanism of Action of RPFl: Potentiator DAMD17-98-1-8072 of Progesterone Receptor and p53-dependent Transcriptional Activity 6. AUTHOR(S) Maria

  2. Mutant p53: Multiple Mechanisms Define Biologic Activity in Cancer.

    PubMed

    Kim, Michael Paul; Zhang, Yun; Lozano, Guillermina

    2015-01-01

    The functional importance of p53 as a tumor suppressor gene is evident through its pervasiveness in cancer biology. The p53 gene is the most commonly altered gene in human cancer; however, not all genetic alterations are biologically equivalent. The majority of alterations involve p53 missense mutations that result in the production of mutant p53 proteins. Such mutant p53 proteins lack normal p53 function and may concomitantly gain novel functions, often with deleterious effects. Here, we review characterized mechanisms of mutant p53 gain of function in various model systems. In addition, we review mutant p53 addiction as emerging evidence suggests that tumors may depend on sustained mutant p53 activity for continued growth. We also discuss the role of p53 in stromal elements and their contribution to tumor initiation and progression. Lastly, current genetic mouse models of mutant p53 in various organ systems are reviewed and their limitations discussed.

  3. Mutant p53: Multiple Mechanisms Define Biologic Activity in Cancer

    PubMed Central

    Kim, Michael Paul; Zhang, Yun; Lozano, Guillermina

    2015-01-01

    The functional importance of p53 as a tumor suppressor gene is evident through its pervasiveness in cancer biology. The p53 gene is the most commonly altered gene in human cancer; however, not all genetic alterations are biologically equivalent. The majority of alterations involve p53 missense mutations that result in the production of mutant p53 proteins. Such mutant p53 proteins lack normal p53 function and may concomitantly gain novel functions, often with deleterious effects. Here, we review characterized mechanisms of mutant p53 gain of function in various model systems. In addition, we review mutant p53 addiction as emerging evidence suggests that tumors may depend on sustained mutant p53 activity for continued growth. We also discuss the role of p53 in stromal elements and their contribution to tumor initiation and progression. Lastly, current genetic mouse models of mutant p53 in various organ systems are reviewed and their limitations discussed. PMID:26618142

  4. Microarray and ChIP-seq data analysis revealed changes in p53-mediated transcriptional regulation in Nutlin-3-treated U2OS cells.

    PubMed

    Zhao, Song; Niu, Feng; Xu, Chang-Yan; Ye, Long; Bi, Gui-Bin; Chen, Lin; Gong, Ping; Tian, Gang; Nie, Tian-Hong

    2015-09-01

    Integrative analysis of chromatin immunoprecipitation-sequencing (ChIP-seq) data and microarray data was performed to illustrate the effect of Nutlin‑3 on promoter selectivity and transcriptional regulation by the tumor suppressor p53 in U2OS human osteosarcoma cells. Raw data (accession number, GSE46642) were downloaded from Gene Expression Omnibus. Differential analyses were performed using package limma of R software. Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed for the differentially expressed genes (DEGs) using the Database for Annotation, Visualization and Integration Discovery. Integrative analysis of ChIP‑seq data and microarray data were confirmed with ChIP‑Array. A total of 565 DEGs were identified, including 373 upregulated genes and 192 downregulated genes. Genes involved in the p53 signaling pathway, cell cycle, DNA replication, cytokine‑cytokine receptor interaction and melanoma were markedly over‑represented in the DEGs. A total of 39 DEGs were directly regulated by p53 and two were the transcription factors (TFs), E2F2 and HOXA1. E2F2 regulated 25 DEGs, while HOXA1 regulated one DEG. The cell cycle, p53 signaling pathway, melanoma and pathways involved in cancer were enriched in the direct and indirect target genes. Changes in the p53‑binding pattern induced by Nutlin‑3 were described in the present study, which may advance the understanding of the regulatory network of p53 in osteosarcoma and aid in the development of novel therapies.

  5. Methylated CpG dinucleotides are the preferential targets for G-to-T transversion mutations induced by benzo[a]pyrene diol epoxide in mammalian cells: similarities with the p53 mutation spectrum in smoking-associated lung cancers.

    PubMed

    Yoon, J H; Smith, L E; Feng, Z; Tang, M; Lee, C S; Pfeifer, G P

    2001-10-01

    A large fraction of the p53 mutations in lung cancers from smokers are G-to-T transversions, a type of mutation that is infrequent in lung cancers from nonsmokers and in most other tumors. Previous studies have indicated that there is an association between G-to-T transversion hotspots in lung cancers and sites of preferential formation of polycyclic aromatic hydrocarbon adducts along the p53 gene. p53 codons containing methylated CpG sequences are preferential targets for formation of adducts by (+/-) anti-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE). To assess the role of CpG methylation in induction of mutations by BPDE, we analyzed BPDE mutagenesis in three CpG methylated target genes: a supF shuttle vector and the cII and lacI transgenes in embryonic mouse fibroblasts. After methylation of the shuttle vector at all CpG sequences, 42% of all G-to-T transversions were at CpG sites compared with 23% in unmethylated DNA. In the cII transgene, which is methylated at CpG sequences in vivo, 83 of 147 (56%) of the BPDE-induced mutations were G-to-T transversions, and 58% (48 of 83) of all G-to-T transversions occurred at methylated CpG sequences. In the lacI gene, 68% (75 of 111) of the BPDE-induced mutations were G-to-T events, and 58 of 75 (77%) of these occurred at methylated CpG sequences. The occurrence of transversion hotspots at methylated CpGs correlated with high levels of BPDE adducts formed at such sites. This situation mirrors the one in the p53 gene in lung cancers from smokers where 236 of 465 (51%) of the G-to-T transversions occurred at methylated CpG sites. These findings further strengthen a link between polycyclic aromatic hydrocarbons present in cigarette smoke and lung cancer mutations and provide evidence that mutational processes other than C-to-T transition mutations can occur selectively at methylated CpG sequences.

  6. The effect of silibinin in enhancing toxicity of temozolomide and etoposide in p53 and PTEN-mutated resistant glioma cell lines.

    PubMed

    Elhag, Rashid; Mazzio, Elizabeth A; Soliman, Karam F A

    2015-03-01

    Glioblastoma multiforme (GBM) is an intractable brain tumor, associated with poor prognosis and low survival rate. Combination therapy such as surgery, radiotherapy and temozolomide is considered standard in overcoming this aggressive cancer, despite poor prognosis. There is a need to identify potential agents, which may augment the chemotherapeutic effects of standard drugs such as temozolomide. In this project, we evaluated the effects of silibinin, a natural plant component of milk thistle seeds, to potentiate toxic effects of chemotherapy drugs such as temozolomide, etoposide and irinotecan on LN229, U87 and A172 (P53 and phosphatase and tensin homolog (PTEN) -tumor suppressor-mutated) glioma cell lines. Data from this work suggest that silibinin was effective in potentiating the cytotoxic efficacy of temozolomide in LN229, U87 and A172 cells. While silibinin reduced survivin protein expression only in LN229 cells, its ability to potentiate cytotoxicity of chemo therapy drugs occurred irrespective of survivin protein levels. The data also demonstrated that silibinin potentiated the effect of etoposide and but not irinotecan in LN229 cells. Future research will be required to evaluate the in vivo efficacy of silibinin to delineate its mechanism of action and its ability to cross the blood-brain barrier.

  7. Combined p16 and p53 expression in cervical cancer of unknown primary and other prognostic parameters : A single-center analysis.

    PubMed

    Yildirim, Müjdat; Müller von der Grün, Jens; Winkelmann, Ria; Fokas, Emmanouil; Rödel, Franz; Ackermann, Hanns; Rödel, Claus; Balermpas, Panagiotis

    2017-04-01

    Cervical cancer of unknown primary (CUP) represents an uncommon and heterogeneous subentity of head and neck cancer. However, both optimal diagnostics and therapy remain unclear. An improved understanding of the underlying pathology is essential to enable future tailored therapies and optimized outcomes. We retrospectively analyzed 53 patients with head and neck CUP and 48 available cervical lymph node specimens. All patients have received radiotherapy between 2007 and 2015. Preradiotherapy involved lymph node specimens were analyzed for p16 and p53 immunoreactivity. The prognostic relevance of the combined p16 and p53 status and other clinical parameters were examined by univariate and multivariate analyses. Median patient age was 61.5 years and median irradiation dose to the involved nodal levels was 66 Gy. Of the 48 evaluated specimens, 13 (27%) were p16-positive and 31 (64.6%) p53-positive. After a median follow up of 32.9 months, patients with p16-negative and simultaneously p53-positive tumors showed a significantly inferior tumor-specific survival (TSS) compared to those with either p16+/p53-, p16+/p53+, or p16-/p53- (univariate: p = 0.055, multivariate: p = 0.038). Other factors with an adverse impact on TSS in the univariate analysis were smoking history (p = 0.032) and nodal stage (p = 0.038). The combined p16- and p53-expression status in cervical metastases of CUP may represent a simple method for risk stratification. Further validation of these biomarkers in large prospective trials is essential to design rational trials for CUP treatment optimization.

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

    SciTech Connect

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

    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 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{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

  9. Targeting Oncogenic Mutant p53 for Cancer Therapy.

    PubMed

    Parrales, Alejandro; Iwakuma, Tomoo

    2015-01-01

    Among genetic alterations in human cancers, mutations in the tumor suppressor p53 gene are the most common, occurring in over 50% of human cancers. The majority of p53 mutations are missense mutations and result in the accumulation of dysfunctional p53 protein in tumors. These mutants frequently have oncogenic gain-of-function activities and exacerbate malignant properties of cancer cells, such as metastasis and drug resistance. Increasing evidence reveals that stabilization of mutant p53 in tumors is crucial for its oncogenic activities, while depletion of mutant p53 attenuates malignant properties of cancer cells. Thus, mutant p53 is an attractive druggable target for cancer therapy. Different approaches have been taken to develop small-molecule compounds that specifically target mutant p53. These include compounds that restore wild-type conformation and transcriptional activity of mutant p53, induce depletion of mutant p53, inhibit downstream pathways of oncogenic mutant p53, and induce synthetic lethality to mutant p53. In this review article, we comprehensively discuss the current strategies targeting oncogenic mutant p53 in cancers, with special focus on compounds that restore wild-type p53 transcriptional activity of mutant p53 and those reducing mutant p53 levels.

  10. Mouse models of p53 functions.

    PubMed

    Lozano, Guillermina

    2010-04-01

    Studies in mice have yielded invaluable insight into our understanding of the p53 pathway. Mouse models with activated p53, no p53, and mutant p53 have queried the role of p53 in development and tumorigenesis. In these models, p53 is activated and stabilized via redundant posttranslational modifications. On activation, p53 initiates two major responses: inhibition of proliferation (via cell-cycle arrest, quiescence, senescence, and differentiation) and induction of apoptosis. Importantly, these responses are cell-type and tumor-type-specific. The analysis of mutant p53 alleles has established a gain-of-function role for p53 mutants in metastasis. The development of additional models that can precisely time the oncogenic events in single cells will provide further insight into the evolution of tumors, the importance of the stroma, and the cooperating events that lead to disruption of the p53 pathway. Ultimately, these models should serve to study the effects of novel drugs on tumor response as well as normal homeostasis.

  11. 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

  12. 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.

  13. The p53-dependent radioadaptive response

    NASA Astrophysics Data System (ADS)

    Ohnishi, Takeo

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

  14. 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

  15. p53 in the game of transposons.

    PubMed

    Wylie, Annika; Jones, Amanda E; Abrams, John M

    2016-11-01

    Throughout the animal kingdom, p53 genes function to restrain mobile elements and recent observations indicate that transposons become derepressed in human cancers. Together, these emerging lines of evidence suggest that cancers driven by p53 mutations could represent "transpospoathies," i.e. disease states linked to eruptions of mobile elements. The transposopathy hypothesis predicts that p53 acts through conserved mechanisms to contain transposon movement, and in this way, prevents tumor formation. How transposon eruptions provoke neoplasias is not well understood but, from a broader perspective, this hypothesis also provides an attractive framework to explore unrestrained mobile elements as inciters of late-onset idiopathic disease. Also see the video abstract here.

  16. Grape seed extract induces anoikis and caspase-mediated apoptosis in human prostate carcinoma LNCaP cells: possible role of ataxia telangiectasia mutated-p53 activation.

    PubMed

    Kaur, Manjinder; Agarwal, Rajesh; Agarwal, Chapla

    2006-05-01

    Prostate cancer is the second leading cancer diagnosed in elderly males in the Western world. Epidemiologic studies suggest that dietary modifications could be an effective approach in reducing various cancers, including prostate cancer, and accordingly cancer-preventive efficacy of dietary nutrients has gained increased attention in recent years. We have recently shown that grape seed extract (GSE) inhibits growth and induces apoptotic death of advanced human prostate cancer DU145 cells in culture and xenograft. Because prostate cancer is initially an androgen-dependent malignancy, here we used LNCaP human prostate cancer cells as a model to assess GSE efficacy and associated mechanisms. GSE treatment of cells led to their detachment within 12 hours, as occurs in anoikis, and caused a significant decrease in live cells mostly due to their apoptotic death. GSE-induced anoikis and apoptosis were accompanied by a strong decrease in focal adhesion kinase levels, but an increase in caspase-3, caspase-9, and poly(ADP-ribose) polymerase cleavage; however, GSE caused both caspase-dependent and caspase-independent apoptosis as evidenced by cytochrome c and apoptosis-inducing factor release into cytosol. Additional studies revealed that GSE causes DNA damage-induced activation of ataxia telangiectasia mutated kinase and Chk2, as well as p53 Ser(15) phosphorylation and its translocation to mitochondria, suggesting this to be an additional mechanism for apoptosis induction. GSE-induced apoptosis, cell growth inhibition, and cell death were attenuated by pretreatment with N-acetylcysteine and involved reactive oxygen species generation. Together, these results show GSE effects in LNCaP cells and suggest additional in vivo efficacy studies in prostate cancer animal models.

  17. Transcriptome analysis of tetraploid cells identifies cyclin D2 as a facilitator of adaptation to genome doubling in the presence of p53

    PubMed Central

    Potapova, Tamara A.; Seidel, Christopher W.; Box, Andrew C.; Rancati, Giulia; Li, Rong

    2016-01-01

    Tetraploidization, or genome doubling, is a prominent event in tumorigenesis, primarily because cell division in polyploid cells is error-prone and produces aneuploid cells. This study investigates changes in gene expression evoked in acute and adapted tetraploid cells and their effect on cell-cycle progression. Acute polyploidy was generated by knockdown of the essential regulator of cytokinesis anillin, which resulted in cytokinesis failure and formation of binucleate cells, or by chemical inhibition of Aurora kinases, causing abnormal mitotic exit with formation of single cells with aberrant nuclear morphology. Transcriptome analysis of these acute tetraploid cells revealed common signatures of activation of the tumor-suppressor protein p53. Suppression of proliferation in these cells was dependent on p53 and its transcriptional target, CDK inhibitor p21. Rare proliferating tetraploid cells can emerge from acute polyploid populations. Gene expression analysis of single cell–derived, adapted tetraploid clones showed up-regulation of several p53 target genes and cyclin D2, the activator of CDK4/6/2. Overexpression of cyclin D2 in diploid cells strongly potentiated the ability to proliferate with increased DNA content despite the presence of functional p53. These results indicate that p53-mediated suppression of proliferation of polyploid cells can be averted by increased levels of oncogenes such as cyclin D2, elucidating a possible route for tetraploidy-mediated genomic instability in carcinogenesis. PMID:27559130

  18. Polymorphisms of H-ras-1 and p53 in breast cancer and lung cancer: a meta-analysis.

    PubMed Central

    Weston, A; Godbold, J H

    1997-01-01

    Certain polymorphic variants of H-ras-1 and p53 have been investigated for an association between inheritance and cancer risk. The results of a metaanalysis, which reviews studies of H-ras-1 rare alleles and p53 codon 72 allelic variants in breast and lung cancer, are presented. The data constituted evidence for elevated risk of both breast and lung cancer with inheritance of rare H-ras-1 alleles. Calculated population attributable risks are 0.092 and 0.037 for breast and lung cancer, respectively. The frequency of the rare H-ras-1 alleles was observed to be greater in African Americans than in Caucasians, and a specific allele (A3.5) that is common in African Americans was found only at low frequency in Caucasians. For p53 a consensus has yet to be reached. Lung cancer studies conducted in Caucasian and African-American populations have found no evidence of risk associated with the proline variant of codon 72. Two similar studies conducted in Japanese populations suggested an association between p53 genotype distribution and lung cancer risk. However, one implicates the proline allele but the other implicates the arginine allele. The frequency of the proline variant is significantly dependent on race. Frequencies have been reported for control populations of Japanese (0.347 and 0.401), Caucasian (0.295, 0.284, and 0.214), African American (0.628 and 0.527), and Mexican American (0.263). PMID:9255581

  19. Alterations in the K-ras and p53 genes in rat lung tumors

    SciTech Connect

    Belinsky, S.A.; Swafford, D.S.; Finch, G.L.; Mitchell, C.E.

    1997-06-01

    Activation of the K-ras protooncogene and inactivation of the p53 tumor suppressor gene are events common to many types of human cancers. Molecular epidemiology studies have associated mutational profiles in these genes with specific exposures. The purpose of this paper is to review investigations that have examined the role of the K-ras and p53 genes in lung tumors induced in the F344 rat by mutagenic and nonmutagenic exposures. Mutation profiles within the K-ras and p53 genes, if present in rat lung tumors, would help to define some of the molecular mechanisms underlying cancer induction by various environmental agents. Pulmonary adenocarcinomas or squamous cell carcinomas were induced by tetranitromethane (TNM), 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK), beryllium metal, plutonium-239, X-ray, diesel exhaust, or carbon black. These agents were chosen because the tumors they produced could arise via different types of DNA damage. Mutation of the K-ras gene was determined by approaches that included DNA transfection, direct sequencing, mismatch hybridization, and restriction fragment length polymorphism analysis. The frequency for mutation of the K-ras gene was exposure dependent. The transition mutations formed could have been derived from deamination of cytosine. Alteration in the p53 gene was assessed by immunohistochemical analysis for p53 protein and single-strand conformation polymorphism (SSCP) analysis of exons 4 to 9. None of the 93 adenocarinomas examined was immunoreactive toward the anti-p53 antibody CM1. In contrast, 14 of 71 squamous cell carcinomas exhibited nuclear p53 immunoreactivity with no correlation to type of exposure. However, SSCP analysis only detected mutations in 2 of 14 squamous cell tumors that were immunoreactive, suggesting that protein stabilization did not stem from mutations within the p53 gene. Thus, the p53 gene does not appear to be involved in the genesis of most rat lung tumors. 2 figs., 2 tabs., 48 refs.

  20. Improvement of gemcitabine sensitivity of p53-mutated pancreatic cancer MiaPaCa-2 cells by RUNX2 depletion-mediated augmentation of TAp73-dependent cell death

    PubMed Central

    Nakamura, M; Sugimoto, H; Ogata, T; Hiraoka, K; Yoda, H; Sang, M; Sang, M; Zhu, Y; Yu, M; Shimozato, O; Ozaki, T

    2016-01-01

    Pancreatic cancer exhibits the worst prognostic outcome among human cancers. Recently, we have described that depletion of RUNX2 enhances gemcitabine (GEM) sensitivity of p53-deficient pancreatic cancer AsPC-1 cells through the activation of TAp63-mediated cell death pathway. These findings raised a question whether RUNX2 silencing could also improve GEM efficacy on pancreatic cancer cells bearing p53 mutation. In the present study, we have extended our study to p53-mutated pancreatic cancer MiaPaCa-2 cells. Based on our current results, MiaPaCa-2 cells were much more resistant to GEM as compared with p53-proficient pancreatic cancer SW1990 cells, and there existed a clear inverse relationship between the expression levels of TAp73 and RUNX2 in response to GEM. Forced expression of TAp73α in MiaPaCa-2 cells significantly promoted cell cycle arrest and/or cell death, indicating that a large amount of TAp73 might induce cell death even in the presence of mutant p53. Consistent with this notion, overexpression of TAp73α stimulated luciferase activity driven by p53/TAp73-target gene promoters in MiaPaCa-2 cells. Similar to AsPC-1 cells, small interfering RNA-mediated knockdown of RUNX2 remarkably enhanced GEM sensitivity of MiPaCa-2 cells. Under our experimental conditions, TAp73 further accumulated in RUNX2-depleted MiaPaCa-2 cells exposed to GEM relative to GEM-treated non-silencing control cells. As expected, silencing of p73 reduced GEM sensitivity of MiPaCa-2 cells. Moreover, GEM-mediated Tyr phosphorylation level of TAp73 was much more elevated in RUNX2-depleted MiaPaCa-2 cells. Collectively, our present findings strongly suggest that knockdown of RUNX2 contributes to a prominent enhancement of GEM sensitivity of p53-mutated pancreatic cancer cells through the activation of TAp73-mediated cell death pathway, and also provides a promising strategy for the treatment of patients with pancreatic cancer bearing p53 mutation. PMID:27294865

  1. TP53 genotype but not p53 immunohistochemical result predicts response to preoperative short-term radiotherapy in rectal cancer.

    PubMed

    Kandioler, Daniela; Zwrtek, Ronald; Ludwig, Carmen; Janschek, Elisabeth; Ploner, Meinhard; Hofbauer, Friedrich; Kührer, Irene; Kappel, Sonja; Wrba, Friedrich; Horvath, Manfred; Karner, Josef; Renner, Karl; Bergmann, Michael; Karner-Hanusch, Judith; Pötter, Richard; Jakesz, Raimund; Teleky, Bela; Herbst, Friedrich

    2002-04-01

    To evaluate and compare the predictive power of p53 gene analysis versus p53 immunohistochemical staining in terms of response to preoperative short-term radiotherapy using 25 Gy in operable rectal cancer. Recent studies show that p53 may be a determinant of radiosensitivity being required for induction of apoptosis in case of radiation-induced DNA damage. Preirradiation biopsy samples of 64 patients with rectal carcinoma were analyzed. Genetic alterations of the p53 gene were detected by complete direct sequencing of exons 2 to 10. Expression of the nuclear phosphoprotein p53 was assessed by immunohistochemical staining. Results were correlated with histopathology of resected specimens and follow-up data, respectively. Mutations of the p53 gene were present in 45% of tumors. Patients with a normal p53 gene had a significant survival advantage. Comparing pre- and postradiotherapy T category, a reduction was seen in patients with normal p53 genotype only. A mutant p53 genotype was highly specific in indicating stable disease concerning T category after irradiation. Protein overexpression was detected in 61%. Overexpression of the p53 protein was not related to survival or response. The concordance between immunohistochemistry and sequencing was only 0.51. The authors show that downstaging after short-term radiation may occur but is seen in tumors with normal p53 gene only. Moreover, p53 genotype but not p53 immunohistochemistry is predictive for response to preoperative short-term radiotherapy and patient survival.

  2. Probing the alpha-helical structural stability of stapled p53 peptides: molecular dynamics simulations and analysis.

    PubMed

    Guo, Zuojun; Mohanty, Udayan; Noehre, Justin; Sawyer, Tomi K; Sherman, Woody; Krilov, Goran

    2010-04-01

    Reactivation of the p53 cell apoptosis pathway through inhibition of the p53-hDM2 interaction is a viable approach to suppress tumor growth in many human cancers and stabilization of the helical structure of synthetic p53 analogs via a hydrocarbon cross-link (staple) has been found to lead to increased potency and inhibition of protein-protein binding (J. Am. Chem. Soc. 129: 5298). However, details of the structure and dynamic stability of the stapled peptides are not well understood. Here, we use extensive all-atom molecular dynamics simulations to study a series of stapled alpha-helical peptides over a range of temperatures in solution. The peptides are found to exhibit substantial variations in predicted alpha-helical propensities that are in good agreement with the experimental observations. In addition, we find significant variation in local structural flexibility of the peptides with the position of the linker, which appears to be more closely related to the observed differences in activity than the absolute alpha-helical stability. These simulations provide new insights into the design of alpha-helical stapled peptides and the development of potent inhibitors of alpha-helical protein-protein interfaces.

  3. Metabolite and transcriptome analysis during fasting suggest a role for the p53-Ddit4 axis in major metabolic tissues

    PubMed Central

    2013-01-01

    Background Fasting induces specific molecular and metabolic adaptions in most organisms. In biomedical research fasting is used in metabolic studies to synchronize nutritional states of study subjects. Because there is a lack of standardization for this procedure, we need a deeper understanding of the dynamics and the molecular mechanisms in fasting. Results We investigated the dynamic changes of liver gene expression and serum parameters of mice at several time points during a 48 hour fasting experiment and then focused on the global gene expression changes in epididymal white adipose tissue (WAT) as well as on pathways common to WAT, liver, and skeletal muscle. This approach produced several intriguing insights: (i) rather than a sequential activation of biochemical pathways in fasted liver, as current knowledge dictates, our data indicates a concerted parallel response; (ii) this first characterization of the transcriptome signature of WAT of fasted mice reveals a remarkable activation of components of the transcription apparatus; (iii) most importantly, our bioinformatic analyses indicate p53 as central node in the regulation of fasting in major metabolic tissues; and (iv) forced expression of Ddit4, a fasting-regulated p53 target gene, is sufficient to augment lipolysis in cultured adipocytes. Conclusions In summary, this combination of focused and global profiling approaches provides a comprehensive molecular characterization of the processes operating during fasting in mice and suggests a role for p53, and its downstream target Ddit4, as novel components in the transcriptional response to food deprivation. PMID:24191950

  4. Development of Yeast as an In Vivo Test Tube to Characterize a Broad Spectrum of p53 Mutations Associated with Breast Cancer

    DTIC Science & Technology

    2002-10-01

    RESULTS a new set of isogenic haploid yeast strains based upon the RADE2 red-white p53 reporter system initially described by Fla- Development of a panel of...diverse p53- dependent responses, which has implications for cancer sus- ACKNOWLEDGMENTS ceptibility and evolution . Our thanks go to Richard Iggo for the...673-682. 78. Wahl, G. M., and A. M. Carr. 2001. The evolution of diverse biological 85. Yu, J., L. Zhang, P. M. Hwang, C. Rago, K. W. Kinzier, and B

  5. Radiation response and cell cycle regulation of p53 rescued malignant keratinocytes

    SciTech Connect

    Niemantsverdriet, Maarten; Jongmans, Wim; Backendorf, Claude . E-mail: backendo@chem.leidenuniv.nl

    2005-10-15

    Mutations in the tumor suppressor gene p53 were found in more than 90% of all human squamous cell carcinomas (SCC). To study the function of p53 in a keratinocyte background, a tetracycline-controlled p53 transgene was introduced into a human SCC cell line (SCC15), lacking endogenous p53. Conditional expression of wild-type p53 protein upon withdrawal of tetracycline was accompanied with increased expression of p21{sup WAF1/Cip1} resulting in reduced cell proliferation. Flow-cytometric analysis revealed that these cells were transiently arrested in the G1/S phase of the cell cycle. However, when SCC15 cells expressing p53 were exposed to ionizing radiation (IR), a clear shift from a G1/S to a G2/M cell cycle arrest was observed. This effect was greatly depending on the presence of wild-type p53, as it was not observed to the same extent in SCC15 cells lacking p53. Unexpectedly, the p53- and IR-dependent G2/M cell cycle arrest in the keratinocyte background was not depending on increased expression or stabilization of 14-3-3{sigma}, a p53-regulated effector of G2/M progression in colorectal cancer cells. In keratinocytes, 14-3-3{sigma} (stratifin) is involved in terminal differentiation and its cell cycle function in this cell type might diverge from the one it fulfills in other cellular backgrounds.

  6. Papillary microcarcinomas of the thyroid gland and immunohistochemical analysis of expression of p53 protein in papillary microcarcinomas.

    PubMed

    Corapcioglu, Demet; Sak, Serpil D; Delibasi, Tuncay; Tonyukuk, Vedia; Kamel, Nuri; Uysal, Ali R; Kocak, Savas; Aydintug, Semih; Erdogan, Gurbuz

    2006-07-05

    Thyroid papillary microcarcinoma (TPM) is defined according to WHO criteria as a thyroid tumor smaller than 1-1.5 cm. TPMs are encountered in 0.5-35.6% of autopsies or surgical specimens where carcinoma had been unsuspected. The purpose of the present study was to evaluate patients who had TPMs in terms of clinical findings, histopathological features and immunohistochemical evidence of expression of the tumor suppressor gene p53. A total of 44 patients with TPMs less than 1.0 cm in diameter were included in the study. The patients were evaluated clinically and the tumors were evaluated in terms of their histopathological and immunohistochemical features, including expression of p53. The female/male ratio was 2.8/1, and the median age at time of diagnosis was 49 years (range 20-71 years). The maximum diameter of the smallest focus was 0.1 mm, and that of the largest was 10 mm microscopically. The mean diameter of all tumors was 5.7 mm. There was no correlation between tumor size and age or gender. Of the TPMs, 72% were found in the right lobe, 24% in the left lobe and 4% in the isthmus. Fine-needle aspiration biopsy provided the diagnosis of TPM in only 43.2% of the patients. All patients were treated with surgery, with 20 undergoing conservative surgery, i.e. lobectomy or isthmusectomy, and 24 undergoing total thyroidectomy. Frozen section provided the diagnosis of TPM in only 56.8% of the patients. We found lymphocytic thyroiditis in 13.6% of patients, follicular variants in 11.9%, capsular invasion in 26.8%, lymph node involvement in 11.9%, soft tissue metastases in the neck in 12.1% and multifocality in 31.7%, and none of these were related to age or gender (p > 0.05). No distant metastases were observed during approximately 10 years of follow up. We found p53 positivity in 34.5% of TPM tumors. However, p53 expression was not statistically related to age or gender. Our findings imply that TPMs may not be entirely innocent since they are associated with signs of

  7. Papillary microcarcinomas of the thyroid gland and immunohistochemical analysis of expression of p53 protein in papillary microcarcinomas

    PubMed Central

    Corapcioglu, Demet; Sak, Serpil D; Delibasi, Tuncay; Tonyukuk, Vedia; Kamel, Nuri; Uysal, Ali R; Kocak, Savas; Aydintug, Semih; Erdogan, Gurbuz

    2006-01-01

    Background Thyroid papillary microcarcinoma (TPM) is defined according to WHO criteria as a thyroid tumor smaller than 1–1.5 cm. TPMs are encountered in 0.5–35.6 % of autopsies or surgical specimens where carcinoma had been unsuspected. The purpose of the present study was to evaluate patients who had TPMs in terms of clinical findings, histopathological features and immunohistochemical evidence of expression of the tumor suppressor gene p53. Methods A total of 44 patients with TPMs less than 1.0 cm in diameter were included in the study. The patients were evaluated clinically and the tumors were evaluated in terms of their histopathological and immunohistochemical features, including expression of p53. Results The female/male ratio was 2.8/1, and the median age at time of diagnosis was 49 years (range 20–71 years). The maximum diameter of the smallest focus was 0.1 mm, and that of the largest was 10 mm microscopically. The mean diameter of all tumors was 5.7 mm. There was no correlation between tumor size and age or gender. Of the TPMs, 72 % were found in the right lobe, 24 % in the left lobe and 4 % in the isthmus. Fine-needle aspiration biopsy provided the diagnosis of TPM in only 43.2 % of the patients. All patients were treated with surgery, with 20 undergoing conservative surgery, i.e. lobectomy or isthmusectomy, and 24 undergoing total thyroidectomy. Frozen section provided the diagnosis of TPM in only 56.8 % of the patients. We found lymphocytic thyroiditis in 13.6% of patients, follicular variants in 11.9%, capsular invasion in 26.8%, lymph node involvement in 11.9%, soft tissue metastases in the neck in 12.1% and multifocality in 31.7 %, and none of these were related to age or gender (p > 0.05). No distant metastases were observed during approximately 10 years of follow up. We found p53 positivity in 34.5 % of TPM tumors. However, p53 expression was not statistically related to age or gender. Conclusion Our findings imply that TPMs may not be

  8. 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.

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

    PubMed

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

    2008-03-01

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

  10. What's new in p53

    PubMed Central

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

    2006-01-01

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

  11. What's new in p53?

    PubMed

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

    2006-07-01

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

  12. p53 expression and its relationship to DNA alterations in bone and soft tissue sarcomas.

    PubMed Central

    Wadayama, B.; Toguchida, J.; Yamaguchi, T.; Sasaki, M. S.; Yamamuro, T.

    1993-01-01

    The p53 gene is one of the best studied tumour suppressor genes. Recently we performed mutation analysis on the p53 gene in a large number of bone and soft tissue sarcomas, and found that approximately one-third of the sarcomas have some type of DNA alteration at the p53 locus (Toguchida et al., 1992). However, the expression of the p53 protein resulting from these alterations still remains to be clarified. In this study, p53 expression in the sarcoma tissues was analysed immunohistochemically using antibody PAb421 (Oncogene Science) and its relationship to DNA alterations was examined. Of 113 tumours, 29 (25.7%) showed positive staining for the p53 protein. These included 19 of 67 osteosarcomas, five of 20 chondrosarcomas, four of 11 malignant fibrous histiocytomas (MFHs) and one Ewing's sarcoma. In chondrosarcomas, most of the p53-positive tumours belonged to highly malignant and atypical tumour types (dedifferentiated or mesenchymal type), suggesting a role for p53 mutation in the progression of cartilaginous tumours. All the cases with a missense mutation showed strongly positive staining, while no immunoreactivity was observed in the remaining three-quarters with DNA alterations including gross rearrangement, frame-shift mutation, nonsense mutation or mutation at splicing site except in one case. These results demonstrated the dominance of the p53 mutations with null protein expression in bone and soft tissue sarcomas, showing a unique characteristic of these types of tumours compared with other malignancies such as colon carcinomas. Images Figure 1 Figure 2 Figure 3 PMID:8260365

  13. Mutant p53 disrupts mammary tissue architecture via the mevalonate pathway.

    PubMed

    Freed-Pastor, William A; Mizuno, Hideaki; Zhao, Xi; Langerød, Anita; Moon, Sung-Hwan; Rodriguez-Barrueco, Ruth; Barsotti, Anthony; Chicas, Agustin; Li, Wencheng; Polotskaia, Alla; Bissell, Mina J; Osborne, Timothy F; Tian, Bin; Lowe, Scott W; Silva, Jose M; Børresen-Dale, Anne-Lise; Levine, Arnold J; Bargonetti, Jill; Prives, Carol

    2012-01-20

    p53 is a frequent target for mutation in human tumors, and mutant p53 proteins can actively contribute to tumorigenesis. We employed a three-dimensional culture model in which nonmalignant breast epithelial cells form spheroids reminiscent of acinar structures found in vivo, whereas breast cancer cells display highly disorganized morphology. We found that mutant p53 depletion is sufficient to phenotypically revert breast cancer cells to a more acinar-like morphology. Genome-wide expression analysis identified the mevalonate pathway as significantly upregulated by mutant p53. Statins and sterol biosynthesis intermediates reveal that this pathway is both necessary and sufficient for the phenotypic effects of mutant p53 on breast tissue architecture. Mutant p53 associates with sterol gene promoters at least partly via SREBP transcription factors. Finally, p53 mutation correlates with highly expressed sterol biosynthesis genes in human breast tumors. These findings implicate the mevalonate pathway as a therapeutic target for tumors bearing mutations in p53.

  14. Identification of the mismatch repair genes PMS2 and MLH1 as p53 target genes by using serial analysis of binding elements

    PubMed Central

    Chen, Jiguo; Sadowski, Ivan

    2005-01-01

    The ability to determine the global location of transcription factor binding sites in vivo is important for a comprehensive understanding of gene regulation in human cells. We have developed a technology, called serial analysis of binding elements (SABE), involving subtractive hybridization of chromatin immunoprecipitation-enriched DNA fragments followed by the generation and analysis of concatamerized sequence tags. We applied the SABE technology to search for p53 target genes in the human genome, and have identified several previously described p53 targets in addition to numerous potentially novel targets, including the DNA mismatch repair genes MLH1 and PMS2. Both of these genes were determined to be responsive to DNA damage and p53 activation in normal human fibroblasts, and have p53-response elements within their first intron. These two genes may serve as a sensor in DNA repair mechanisms and a critical determinant for the decision between cell-cycle arrest and apoptosis. These results also demonstrate the potential for use of SABE as a broadly applicable means to globally identify regulatory elements for human transcription factors in vivo. PMID:15781865

  15. Tumor-specific p53 sequences in blood and peritoneal fluid of women with epithelial ovarian cancer.

    PubMed

    Swisher, Elizabeth M; Wollan, Melissa; Mahtani, Sarita M; Willner, Julia B; Garcia, Rochelle; Goff, Barbara A; King, Mary-Claire

    2005-09-01

    Free tumor DNA in body fluids may be an important biomarker. We tested whether tumor-specific mutated p53 DNA can be detected in blood and peritoneal fluid from women with epithelial ovarian cancer. Sequencing of tumor DNA identified somatic p53 mutations. Free DNA from matched blood or peritoneal fluid was evaluated for the tumor-specific p53 mutation using a ligase detection reaction. Sixty-nine of 137 tumors (50%) had p53 mutations. Plasma or serum from 21 (30%) of the 69 informative cases contained the tumor-specific p53 mutation. Circulating tumor was an independent predictor of decreased survival in multivariate analysis (P=.02). We detected tumor DNA in peritoneal fluid in 28 of 30 (93%) cases, including all 6 cases with negative cytology. One third of women with ovarian cancer have circulating tumor DNA and an associated reduced survival. Free tumor DNA can be detected in the majority of peritoneal fluid samples.

  16. A p53 Super-tumor Suppressor Reveals a Tumor Suppressive p53-Ptpn14-Yap Axis in Pancreatic Cancer.

    PubMed

    Mello, Stephano S; Valente, Liz J; Raj, Nitin; Seoane, Jose A; Flowers, Brittany M; McClendon, Jacob; Bieging-Rolett, Kathryn T; Lee, Jonghyeob; Ivanochko, Danton; Kozak, Margaret M; Chang, Daniel T; Longacre, Teri A; Koong, Albert C; Arrowsmith, Cheryl H; Kim, Seung K; Vogel, Hannes; Wood, Laura D; Hruban, Ralph H; Curtis, Christina; Attardi, Laura D

    2017-10-09

    The p53 transcription factor is a critical barrier to pancreatic cancer progression. To unravel mechanisms of p53-mediated tumor suppression, which have remained elusive, we analyzed pancreatic cancer development in mice expressing p53 transcriptional activation domain (TAD) mutants. Surprisingly, the p53(53,54) TAD2 mutant behaves as a "super-tumor suppressor," with an enhanced capacity to both suppress pancreatic cancer and transactivate select p53 target genes, including Ptpn14. Ptpn14 encodes a negative regulator of the Yap oncoprotein and is necessary and sufficient for pancreatic cancer suppression, like p53. We show that p53 deficiency promotes Yap signaling and that PTPN14 and TP53 mutations are mutually exclusive in human cancers. These studies uncover a p53-Ptpn14-Yap pathway that is integral to p53-mediated tumor suppression. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  17. Mutant p53(R270H) gain of function phenotype in a mouse model for oncogene-induced mammary carcinogenesis.

    PubMed

    Heinlein, Christina; Krepulat, Frauke; Löhler, Jürgen; Speidel, Daniel; Deppert, Wolfgang; Tolstonog, Genrich V

    2008-04-15

    In human breast cancer, mutations in the p53 gene are associated with poor prognosis. However, analysis of patient data so far did not clarify, whether missense point mutations in the p53 gene, in addition to causing loss of wild-type p53 function, also confer a gain of function phenotype to the encoded mutant p53. As heterogeneity of patient material and data might obscure a clear answer, we studied the effects of a coexpressed mutant p53(R270H) in transgenic mice in which SV40 early proteins initiate the development of mammary adenocarcinoma (WAP-T mice). In such tumors the endogenous wild-type p53 is functionally compromised by complex formation with SV40 T-antigen, thereby constituting a loss of wild-type p53 function situation that allowed analysis of the postulated gain of function effects of mutant p53(R270H). We found that mutant p53(R270H) in bi-transgenic mice enhanced the transition from intraepithelial neoplasia to invasive carcinoma, resulting in a higher frequency of invasive carcinoma per gland and per mouse, a more severe tumor phenotype, and more frequent pulmonary metastasis. Surprisingly, mutant p53(R270H) in this system does not increase genomic instability. Therefore, other postulated gain of function activities of mutant p53 must be responsible for the effects described here.

  18. Impact of low-frequency hotspot mutation R282Q on the structure of p53 DNA-binding domain as revealed by crystallography at 1.54 Å resolution

    SciTech Connect

    Tu, Chao; Tan, Yu-Hong; Shaw, Gary; Zhou, Zheng; Bai, Yawen; Luo, Ray; Ji, Xinhua

    2008-05-01

    The impact of hotspot mutation R282Q on the structure of human p53 DNA-binding domain has been characterized by X-ray crystallography and molecular-dynamics simulations. Tumor suppressor p53 is a sequence-specific DNA-binding protein and its central DNA-binding domain (DBD) harbors six hotspots (Arg175, Gly245, Arg248, Arg249, Arg273 and Arg282) for human cancers. Here, the crystal structure of a low-frequency hotspot mutant, p53DBD(R282Q), is reported at 1.54 Å resolution together with the results of molecular-dynamics simulations on the basis of the structure. In addition to eliminating a salt bridge, the R282Q mutation has a significant impact on the properties of two DNA-binding loops (L1 and L3). The L1 loop is flexible in the wild type, but it is not flexible in the mutant. The L3 loop of the wild type is not flexible, whereas it assumes two conformations in the mutant. Molecular-dynamics simulations indicated that both conformations of the L3 loop are accessible under biological conditions. It is predicted that the elimination of the salt bridge and the inversion of the flexibility of L1 and L3 are directly or indirectly responsible for deactivating the tumor suppressor p53.

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

    PubMed

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

    2017-03-01

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

  20. Mechanisms That Enhance Sustainability of p53 Pulses

    PubMed Central

    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. PMID:23755198

  1. 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.

  2. Multiple stress signals activate mutant p53 in vivo

    PubMed Central

    Suh, Young-Ah; Post, Sean M.; Elizondo-Fraire, Ana C.; Maccio, Danela R.; Jackson, James G.; El-Naggar, Adel K.; Van Pelt, Carolyn; Terzian, Tamara; Lozano, Guillermina

    2012-01-01

    p53 levels are tightly regulated in normal cells, and thus the wild-type p53 protein is nearly undetectable until stimulated through a variety of stresses. In response to stress, p53 is released from its negative regulators, mainly Mdm2, allowing p53 to be stabilized to activate cell cycle arrest, senescence, and apoptosis programs. Many of the upstream signals that regulate wild type p53 are known; however, limited information for the regulation of mutant p53 exists. Previously, we demonstrated that wild-type and mutant p53R172H are regulated in a similar manner in the absence of Mdm2 or p16. Additionally, this stabilization of mutant p53 is responsible for the gain-of-function metastatic phenotype observed in the mouse. In this report, we examined the role of oncogenes, DNA damage, and reactive oxygen species, signals that stabilize wild type p53, on the stabilization of mutant p53 in vivo and the consequences of this expression on tumor formation and survival. These factors stabilized mutant p53 protein which often times contributed to exacerbated tumor phenotypes. These findings, coupled with the fact that patients carry p53 mutations without stabilization of p53, suggest that personalized therapeutic schemes may be needed for individual patients depending on their p53 status. PMID:21983037

  3. Nucleolar stress with and without p53

    PubMed Central

    James, Allison; Wang, Yubo; Raje, Himanshu; Rosby, Raphyel; DiMario, Patrick

    2014-01-01

    A veritable explosion of primary research papers within the past 10 years focuses on nucleolar and ribosomal stress, and for good reason: with ribosome biosynthesis consuming ~80% of a cell’s energy, nearly all metabolic and signaling pathways lead ultimately to or from the nucleolus. We begin by describing p53 activation upon nucleolar stress resulting in cell cycle arrest or apoptosis. The significance of this mechanism cannot be understated, as oncologists are now inducing nucleolar stress strategically in cancer cells as a potential anti-cancer therapy. We also summarize the human ribosomopathies, syndromes in which ribosome biogenesis or function are impaired leading to birth defects or bone narrow failures; the perplexing problem in the ribosomopathies is why only certain cells are affected despite the fact that the causative mutation is systemic. We then describe p53-independent nucleolar stress, first in yeast which lacks p53, and then in other model metazoans that lack MDM2, the critical E3 ubiquitin ligase that normally inactivates p53. Do these presumably ancient p53-independent nucleolar stress pathways remain latent in human cells? If they still exist, can we use them to target >50% of known human cancers that lack functional p53? PMID:25482194

  4. Nucleolar stress with and without p53.

    PubMed

    James, Allison; Wang, Yubo; Raje, Himanshu; Rosby, Raphyel; DiMario, Patrick

    2014-01-01

    A veritable explosion of primary research papers within the past 10 years focuses on nucleolar and ribosomal stress, and for good reason: with ribosome biosynthesis consuming ~80% of a cell's energy, nearly all metabolic and signaling pathways lead ultimately to or from the nucleolus. We begin by describing p53 activation upon nucleolar stress resulting in cell cycle arrest or apoptosis. The significance of this mechanism cannot be understated, as oncologists are now inducing nucleolar stress strategically in cancer cells as a potential anti-cancer therapy. We also summarize the human ribosomopathies, syndromes in which ribosome biogenesis or function are impaired leading to birth defects or bone narrow failures; the perplexing problem in the ribosomopathies is why only certain cells are affected despite the fact that the causative mutation is systemic. We then describe p53-independent nucleolar stress, first in yeast which lacks p53, and then in other model metazoans that lack MDM2, the critical E3 ubiquitin ligase that normally inactivates p53. Do these presumably ancient p53-independent nucleolar stress pathways remain latent in human cells? If they still exist, can we use them to target >50% of known human cancers that lack functional p53?

  5. Annexin A2 and PSF proteins interact with p53 IRES and regulate translation of p53 mRNA.

    PubMed

    Sharathchandra, Arandkar; Lal, Ridhima; Khan, Debjit; Das, Saumitra

    2012-12-01

    p53 mRNA has been shown to be translated into two isoforms, full-length p53 (FL-p53) and a truncated isoform ΔN-p53, which modulates the functions of FL-p53 and also has independent functions. Previously, we have shown that translation of p53 and ΔN-p53 can be initiated at Internal Ribosome Entry Sites (IRES). These two IRESs were shown to regulate the translation of p53 and ΔN-p53 in a distinct cell-cycle phase-dependent manner. Earlier observations from our laboratory also suggest that the structural integrity of the p53 RNA is critical for IRES function and is compromised by mutations that affect the structure as well as RNA protein interactions. In the current study, using RNA affinity approach we have identified Annexin A2 and PTB associated Splicing Factor (PSF/SFPQ) as novel ITAFs for p53 IRESs. We have showed that the purified Annexin A2 and PSF proteins specifically bind to p53 IRES elements. Interestingly, in the presence of calcium ions Annexin A2 showed increased binding with p53 IRES. Immunopulldown experiments suggest that these two proteins associate with p53 mRNA ex vivo as well. Partial knockdown of Annexin A2 and PSF showed decrease in p53 IRES activity and reduced levels of both the p53 isoforms. More importantly the interplay between Annexin A2, PSF and PTB proteins for binding to p53mRNA appears to play a crucial role in IRES function. Taken together, our observations suggest pivotal role of two new trans-acting factors in regulating the p53-IRES function, which in turn influences the synthesis of p53 isoforms.

  6. Quaternary structure of the specific p53–DNA complex reveals the mechanism of p53 mutant dominance

    PubMed Central

    Aramayo, Ricardo; Sherman, Michael B.; Brownless, Kathryne; Lurz, Rudi; Okorokov, Andrei L.; Orlova, Elena V.

    2011-01-01

    The p53 tumour suppressor is a transcriptional activator that controls cell fate in response to various stresses. p53 can initiate cell cycle arrest, senescence and/or apoptosis via transactivation of p53 target genes, thus preventing cancer onset. Mutations that impair p53 usually occur in the core domain and negate the p53 sequence-specific DNA binding. Moreover, these mutations exhibit a dominant negative effect on the remaining wild-type p53. Here, we report the cryo electron microscopy structure of the full-length p53 tetramer bound to a DNA-encoding transcription factor response element (RE) at a resolution of 21 Å. While two core domains from both dimers of the p53 tetramer interact with DNA within the complex, the other two core domains remain available for binding another DNA site. This finding helps to explain the dominant negative effect of p53 mutants based on the fact that p53 dimers are formed co-translationally before the whole tetramer assembles; therefore, a single mutant dimer would prevent the p53 tetramer from binding DNA. The structure indicates that the Achilles’ heel of p53 is in its dimer-of-dimers organization, thus the tetramer activity can be negated by mutation in only one allele followed by tumourigenesis. PMID:21764777

  7. Mutant p53 promotes tumor progression and metastasis by the endoplasmic reticulum UDPase ENTPD5

    PubMed Central

    Vogiatzi, Fotini; Brandt, Dominique T.; Schneikert, Jean; Fuchs, Jeannette; Grikscheit, Katharina; Wanzel, Michael; Pavlakis, Evangelos; Charles, Joël P.; Timofeev, Oleg; Nist, Andrea; Mernberger, Marco; Kantelhardt, Eva J.; Siebolts, Udo; Bartel, Frank; Jacob, Ralf; Rath, Ariane; Moll, Roland; Grosse, Robert; Stiewe, Thorsten

    2016-01-01

    Mutations in the p53 tumor suppressor gene are the most frequent genetic alteration in cancer and are often associated with progression from benign to invasive stages with metastatic potential. Mutations inactivate tumor suppression by p53, and some endow the protein with novel gain of function (GOF) properties that actively promote tumor progression and metastasis. By comparative gene expression profiling of p53-mutated and p53-depleted cancer cells, we identified ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a mutant p53 target gene, which functions as a uridine 5′-diphosphatase (UDPase) in the endoplasmic reticulum (ER) to promote the folding of N-glycosylated membrane proteins. A comprehensive pan-cancer analysis revealed a highly significant correlation between p53 GOF mutations and ENTPD5 expression. Mechanistically, mutp53 is recruited by Sp1 to the ENTPD5 core promoter to induce its expression. We show ENTPD5 to be a mediator of mutant p53 GOF activity in clonogenic growth, architectural tissue remodeling, migration, invasion, and lung colonization in an experimental metastasis mouse model. Our study reveals folding of N-glycosylated membrane proteins in the ER as a mechanism underlying the metastatic progression of tumors with mutp53 that could provide new possibilities for cancer treatment. PMID:27956623

  8. Mutant p53 promotes tumor progression and metastasis by the endoplasmic reticulum UDPase ENTPD5.

    PubMed

    Vogiatzi, Fotini; Brandt, Dominique T; Schneikert, Jean; Fuchs, Jeannette; Grikscheit, Katharina; Wanzel, Michael; Pavlakis, Evangelos; Charles, Joël P; Timofeev, Oleg; Nist, Andrea; Mernberger, Marco; Kantelhardt, Eva J; Siebolts, Udo; Bartel, Frank; Jacob, Ralf; Rath, Ariane; Moll, Roland; Grosse, Robert; Stiewe, Thorsten

    2016-12-27

    Mutations in the p53 tumor suppressor gene are the most frequent genetic alteration in cancer and are often associated with progression from benign to invasive stages with metastatic potential. Mutations inactivate tumor suppression by p53, and some endow the protein with novel gain of function (GOF) properties that actively promote tumor progression and metastasis. By comparative gene expression profiling of p53-mutated and p53-depleted cancer cells, we identified ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a mutant p53 target gene, which functions as a uridine 5'-diphosphatase (UDPase) in the endoplasmic reticulum (ER) to promote the folding of N-glycosylated membrane proteins. A comprehensive pan-cancer analysis revealed a highly significant correlation between p53 GOF mutations and ENTPD5 expression. Mechanistically, mutp53 is recruited by Sp1 to the ENTPD5 core promoter to induce its expression. We show ENTPD5 to be a mediator of mutant p53 GOF activity in clonogenic growth, architectural tissue remodeling, migration, invasion, and lung colonization in an experimental metastasis mouse model. Our study reveals folding of N-glycosylated membrane proteins in the ER as a mechanism underlying the metastatic progression of tumors with mutp53 that could provide new possibilities for cancer treatment.

  9. G-actin guides p53 nuclear transport: potential contribution of monomeric actin in altered localization of mutant p53

    PubMed Central

    Saha, Taniya; Guha, Deblina; Manna, Argha; Panda, Abir Kumar; Bhat, Jyotsna; Chatterjee, Subhrangsu; Sa, Gaurisankar

    2016-01-01

    p53 preserves genomic integrity by restricting anomaly at the gene level. Till date, limited information is available for cytosol to nuclear shuttling of p53; except microtubule-based trafficking route, which utilizes minus-end directed motor dynein. The present study suggests that monomeric actin (G-actin) guides p53 traffic towards the nucleus. Histidine-tag pull-down assay using purified p53(1–393)-His and G-actin confirms direct physical association between p53 and monomeric G-actin. Co-immunoprecipitation data supports the same. Confocal imaging explores intense perinuclear colocalization between p53 and G-actin. To address atomistic details of the complex, constraint-based docked model of p53:G-actin complex was generated based on crystal structures. MD simulation reveals that p53 DNA-binding domain arrests very well the G-actin protein. Docking benchmark studies have been carried out for a known crystal structure, 1YCS (complex between p53DBD and BP2), which validates the docking protocol we adopted. Co-immunoprecipitation study using “hot-spot” p53 mutants suggested reduced G-actin association with cancer-associated p53 conformational mutants (R175H and R249S). Considering these findings, we hypothesized that point mutation in p53 structure, which diminishes p53:G-actin complexation results in mutant p53 altered subcellular localization. Our model suggests p53Arg249 form polar-contact with Arg357 of G-actin, which upon mutation, destabilizes p53:G-actin interaction and results in cytoplasmic retention of p53R249S. PMID:27601274

  10. Mutant p53: One, No One, and One Hundred Thousand.

    PubMed

    Walerych, Dawid; Lisek, Kamil; Del Sal, Giannino

    2015-01-01

    Encoded by the mutated variants of the TP53 tumor suppressor gene, mutant p53 proteins are getting an increased experimental support as active oncoproteins promoting tumor growth and metastasis. p53 missense mutant proteins are losing their wild-type tumor suppressor activity and acquire oncogenic potential, possessing diverse transforming abilities in cell and mouse models. Whether various mutant p53s differ in their oncogenic potential has been a matter of debate. Recent discoveries are starting to uncover the existence of mutant p53 downstream programs that are common to different mutant p53 variants. In this review, we discuss a number of studies on mutant p53, underlining the advantages and disadvantages of alternative experimental approaches that have been used to describe the numerous mutant p53 gain-of-function activities. Therapeutic possibilities are also discussed, taking into account targeting either individual or multiple mutant p53 proteins in human cancer.

  11. Activation and activities of the p53 tumour suppressor protein

    PubMed Central

    Bálint, É; Vousden, K H

    2001-01-01

    The p53 tumour suppressor protein inhibits malignant progression by mediating cell cycle arrest, apoptosis or repair following cellular stress. One of the major regulators of p53 function is the MDM2 protein, and multiple forms of cellular stress activate p53 by inhibiting the MDM2-mediated degradation of p53. Mutations in p53, or disruption of the pathways that allow activation of p53, seem to be a general feature of all cancers. Here we review recent advances in our understanding of the pathways that regulate p53 and the pathways that are induced by p53, as well as their implications for cancer therapy. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11747320

  12. Virilizing Adrenocortical Carcinoma Invading the Right Atrium with Histological High-Grade Malignancy and p53 Mutation in a 3-Year-Old Child: Indication of Post Operative Adjuvant Chemotherapy.

    PubMed

    Nagasaki, Keisuke; Horikawa, Reiko; Nagaishi, Jun-Ichi; Honna, Toshiro; Sekiguchi, Akihiko; Tsunematsu, Yukiko; Tanaka, Toshiaki

    2004-01-01

    We present a 3-yr-old girl with a virilizing adrenocortical carcinoma invading into the right atrium with histological high-grade malignancy and p53 mutation. Development of facial acne and pubic hair were noted at 3 yr and 2 mo. The levels of androgens were high. Diurnal variation in ACTH and cortisol were absent. Abdominal computed tomography revealed a large right suprarenal mass, with extension into the inferior vena cava and right atrium. Based on the diagnosis of a right virilizing adrenocortical tumor with Cushing syndrome, surgery was performed by a combined thoracoabdominal approach with the patient on cardiopulmonary bypass. The tumor was 7 × 5.5 × 3.5 cm in size, and weighed 95 g. The histological diagnosis was adrenocartical carcinoma with high-grade malignancy according to the category of Weiss. A heterozygous mutation of the p53 tumor-suppressor gene (codon 248 CGC→TGG) was found. We did not perform adjuvant chemotherapy because of radical resection on macroscopic observation and no metastasis in radiological findings. Five months after the surgery, her chest X ray and computed tomography revealed multiple lung metastases and a single liver metastasis. In this type of patient with histological high-grade malignancy and p53 mutations, postoperative adjuvant chemotherapy is indicated even if macroscopic total surgical removal had been performed.

  13. P53 Gene Mutagenesis in Breast Cancer

    DTIC Science & Technology

    2005-03-01

    suppressor gene in sporadic breast tumours . 1991. Loss of chromosome 17 pl3 sequences and mutation of p53 Oncogene 5 :1573-1579. in human breast...COVERED March 2005 Final (I Aug 2000 - 1 Feb 2004) 4. TITLE AND SUBTITLE 5 . FUNDING NUMBERS p53 Gene Mutagenesis in Breast Cancer DAMD17-00-1-0204 6. AUTHOR...The central hypothesis of this proposal is that variability in the patterns of p 5 3 mutagenesis in breast cancer reflects differences in exposures to

  14. Arsenic promotes centrosome abnormalities and cell colony formation in p53 compromised human lung cells

    SciTech Connect

    Liao Weiting; Lin Pinpin; Cheng, T.-S.; Yu, H.-S.; Chang, Louis W.

    2007-12-01

    Epidemiological evidence indicated that residents, especially cigarette smokers, in arseniasis areas had significantly higher lung cancer risk than those living in non-arseniasis areas. Thus, an interaction between arsenic and cigarette smoking in lung carcinogenesis was suspected. p53 dysfunction or mutation in lung epithelial cells was frequently observed in cigarette smokers. Our present study was to explore the differential effects by arsenic on H1355 cells (human lung adenocarcinoma cell line with mutation in p53), BEAS-2B (immortalized lung epithelial cell with functional p53) and pifithrin-{alpha}-treated BEAS-2B cells (p53-inhibited cells). These cells were treated with different doses of sodium arsenite (0, 0.1, 1, 5 and 10 {mu}M) for 48 h. A greater reduction in cell viability was observed in the BEAS-2B cells vs. p53 compromised cells (H1355 or p53-inhibited BEAS-2B). Similar observation was also made on 7-day cell survival (growth) study. TUNEL analysis confirmed that there was indeed a significantly reduced arsenite-induced apoptosis found in p53-compromised cells. Centrosomal abnormality has been attributed to eventual chromosomal missegregation, aneuploidy and tumorigenesis. In our present study, reduced p21 and Gadd45a expressions and increased centrosomal abnormality (atopic and multiple centrosomes) were observed in both arsenite-treated H1355 and p53-inhibited BEAS-2B cells as compared with similarly treated BEAS-2B cells. Increased anchorage-independent growth (colony formation) of BEAS-2B cells co-treated with pifithrin-{alpha} and 5 {mu}M sodium arsenite was also observed in soft agar. Our present investigation demonstrated that arsenic would act specifically on p53 compromised cells (either with p53 dysfunction or inhibited) to induce centrosomal abnormality and colony formation. These findings provided strong evidence on the carcinogenic promotional role of arsenic, especially under the condition of p53 dysfunction.

  15. Relative genomic stability of adipose tissue derived mesenchymal stem cells: analysis of ploidy, H19 long non-coding RNA and p53 activity.

    PubMed

    Ravid, Orly; Shoshani, Ofer; Sela, Meirav; Weinstock, Ada; Sadan, Tommy Weiss; Gur, Eyal; Zipori, Dov; Shani, Nir

    2014-12-17

    Mesenchymal stem cells (MSCs) are multipotent and have been derived from various tissues. Although MSCs share many basic features, they often display subtle tissue specific differences. We previously demonstrated that bone marrow (BM) MSCs frequently become polyploid in culture. This tendency was mediated by a reduction in the expression of H19 long non-coding RNA during the transition from a diploid to a polyploid state. MSCs were derived from both BM and adipose tissue of mice and expanded under normoxic and hypoxic culture conditions. Cells were stained by propidium iodide and their ploidy was evaluated by FACS. Gene expression of independent MSC preparations was compared by quantitative real time PCR and protein expression levels by Western blot analysis. p53 silencing in MSCs was performed by a specific small hairpin RNA (shRNA). We set to examine whether genomic instability is common to MSCs originating from different tissues. It is demonstrated that adipose derived MSCs (ASCs) tend to remain diploid during culture while a vast majority of BM MSCs become polyploid. The diploid phenotype of ASCs is correlated with reduced H19 expression compared to BM MSCs. Under hypoxic conditions (3% oxygen) both ASCs and BM MSCs demonstrate increased RNA expression of H19 and Vascular endothelial growth factor A. Importantly, ASC gene expression is significantly less variable than BM MSCs under both oxygen conditions, indicating to their superior homogeneity. Gene expression analysis revealed that p53 target genes, often induced by DNA damage, are up-regulated in ASCs under basal conditions. However, p53 activation following treatment with DNA damaging agents was strongly elevated in BM MSCs compared to ASCs. We found that p53 is involved in maintaining the stable diploid state of ASCs as p53 shRNA induced ploidy changes in ASCs but not in BM MSCs. The increased genomic stability of murine ASCs together with their lower H19 expression and relative homogeneity suggest a

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

    PubMed Central

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

    2016-01-01

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

  17. The p53 circuit board

    PubMed Central

    Sullivan, Kelly D.; Gallant-Behm, Corrie L.; Henry, Ryan E.; Fraikin, Jean-Luc; Espinosa, Joaquín M.

    2012-01-01

    The p53 tumor suppressor is embedded in a large gene network controlling diverse cellular and organismal phenotypes. Multiple signaling pathways converge onto p53 activation, mostly by relieving the inhibitory effects of its repressors, MDM2 and MDM4. In turn, signals originating from increased p53 activity diverge into distinct effector pathways to deliver a specific cellular response to the activating stimuli. Much attention has been devoted to dissecting how the various input pathways trigger p53 activation and how the activity of the p53 protein itself can be modulated by a plethora of co-factors and post-translational modifications. In this review we will focus instead on the multiple configurations of the effector pathways. We will discuss how p53-generated signals are transmitted, amplified, resisted and eventually integrated by downstream gene circuits operating at the transcriptional, post-transcriptional and post-translational level. We will also discuss how context-dependent variations in these gene circuits define the cellular response to p53 activation and how they may impact the clinical efficacy of p53-based targeted therapies. PMID:22333261

  18. p53 alterations in oesophageal cancer: association with clinicopathological features, risk factors, and survival.

    PubMed Central

    Casson, A G; Tammemagi, M; Eskandarian, S; Redston, M; McLaughlin, J; Ozcelik, H

    1998-01-01

    AIM: To characterise the spectrum of p53 alterations (gene mutations and protein accumulation) in a consecutive series of surgically resected oesophageal cancers, and to evaluate associations with clinicopathological findings (age, sex, tumour histology, grade, and stage), potential risk factors (alcohol, tobacco, hot beverage consumption, history of gastrooesophageal reflux disease and antacid use), and survival. METHODS: The case series comprised 61 sequentially accrued patients with primary oesophageal carcinomas. Genomic DNA was extracted from banked (frozen) tumours and matched normal mucosal tissue; p53 mutations (exons 4-10) were studied by means of polymerase chain reaction (PCR)/single strand conformation polymorphism (SSCP) analysis and DNA sequencing. Immunohistochemistry (DO7, CM1) was used to assess cell nuclear p53 protein accumulation. Risk factor data, overall and disease free survival were measured prospectively, and analysis was carried out at the univariate level using Kaplan-Meier survival curves with log rank tests, and in multivariate analysis using Cox's proportional hazards models (parsimonious and fully adjusted). RESULTS: p53 mutations were found in 59% (36 of 61) and p53 protein accumulation was detected in 39% (24 of 61) of oesophageal cancers. Eighty eight per cent (23 of 26) of poorly differentiated tumours had p53 alterations compared with 57% (20 of 35) of moderate/well differentiated tumours (odds ratio (OR) = 5.575; p = 0.013). p53 mutations increased significantly with increasing consumption of hot beverages (measured by the average temperature of beverage, number consumed daily, and an index made by multiplying the two variables together) using both univariate (OR = 18.6; p = 0.0025) and multivariate (OR = 24.5; p = 0.0025) analysis. p53 alterations were associated with reduced disease free and overall survival (p = 0.051, log rank), with a univariate (unadjusted) hazard ratio (HR) of 2.241 (95% confidence limits (CL) = 0.973, 5

  19. 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

  20. Deconstructing p53 transcriptional networks in tumor suppression.

    PubMed

    Bieging, Kathryn T; Attardi, Laura D

    2012-02-01

    p53 is a pivotal tumor suppressor that induces apoptosis, cell-cycle arrest and senescence in response to stress signals. Although p53 transcriptional activation is important for these responses, the mechanisms underlying tumor suppression have been elusive. To date, no single or compound mouse knockout of specific p53 target genes has recapitulated the dramatic tumor predisposition that characterizes p53-null mice. Recently, however, analysis of knock-in mice expressing p53 transactivation domain mutants has revealed a group of primarily novel direct p53 target genes that may mediate tumor suppression in vivo. We present here an overview of well-known p53 target genes and the tumor phenotypes of the cognate knockout mice, and address the recent identification of new p53 transcriptional targets and how they enhance our understanding of p53 transcriptional networks central for tumor suppression.

  1. Comparative study of p63 and p53 expression in tissue microarrays of malignant melanomas.

    PubMed

    Brinck, Ulrich; Ruschenburg, Ilka; Di Como, Charles J; Buschmann, Nadine; Betke, Herbert; Stachura, Jerzy; Cordon-Cardo, Carlos; Korabiowska, Monika

    2002-12-01

    p63 is a known homologue of p53. In contrast to p53, however, p63 mutations are rarely seen in tumours. There have been several reports that p63 plays a regulatory role in the normal differentiation of cells, whereas its role in tumour biology must still be elucidated. The main aim of this study was to compare p63 and p53 expression in tissue microarrays of malignant melanomas and to establish any prognostic significance. p63 expression was found in 2 out of 59 tumours, both pT4. The p63 index did not exceed 30%. p53 expression was found in 27 out of 59 melanomas, with maximal expression in up to 80% of tumour cells. There were no correlations observed between the two markers. Multivariate analysis confirmed the prognostically independent role of p53. This study also confirmed that tissue microarrays can be used effectively for evaluation of the expression of certain tumour markers.

  2. Low-level c-myc amplification in human colonic carcinoma cell lines and tumors: a frequent, p53-independent mutation associated with improved outcome in a randomized multi-institutional trial.

    PubMed

    Augenlicht, L H; Wadler, S; Corner, G; Richards, C; Ryan, L; Multani, A S; Pathak, S; Benson, A; Haller, D; Heerdt, B G

    1997-05-01

    Human colonic cancer is associated with multiple genetic deletions, mutations, and alterations in gene expression; in contrast, gene amplification has not been recognized as a prominent characteristic of human colonic tumors. Although the c-myc gene is overexpressed in approximately 70% of human colonic cancers, previous studies have not detected frequent gene amplification or rearrangement of c-myc in these tumors, although such amplification has been reported in chemically induced rodent colon cancer and quantitative analysis of gene copy number has shown the gene to be amplified at a low level in mucinous and poorly differentiated human colon carcinomas. Using rigorously controlled blot methodology, we have established that the c-myc gene, located at 8q21, exhibited amplification of 87% to 35-fold in 7 of 10 human colonic carcinoma cell lines. This was highly significant even at a low level of amplification in HT29 cells (P < 0.0001). Cytogenetic analysis by G-banding did not detect aneuploidy involving chromsome 8q, suggesting that the amplification for the c-myc gene on 8q was relatively specific, and this was consistent with a lack of amplification detected for the c-mos gene on 8q24, which was assayed similarly. The same methodology then revealed amplification of c-myc from 1.5-fold to 5-fold in 32% of tumors from 149 patients entered into a multi-institutional Phase III study of adjuvant therapy for colon cancer. c-myc status was not related to time to recurrence or death, but low levels of c-myc amplification identified a subset of patients who showed a statistically significant increase in disease-free survival, and a corresponding trend to longer overall survival, in response to adjuvant therapy with 5-fluorouracil plus levamisole. Presence of c-myc amplification was not related to incidence of p53 mutations.