WorldWideScience

Sample records for altered p53 cdkn2a

  1. Role of p53 and CDKN2A Inactivation in Human Squamous Cell Carcinomas

    Directory of Open Access Journals (Sweden)

    Alessia Pacifico

    2007-04-01

    Full Text Available p53 tumor suppressor gene is the most commonly mutated gene in human and mouse cancers. Disruption of the p53 and Rb pathways is a fundamental trend of most human cancer cells. Inactivation of CDKN2A can lead to deregulation of these two pathways. Genetic abnormalities in CDKN2A gene have been well documented in human melanoma but their involvement in human nonmelanoma skin cancer (NMSC and in particular in squamous cell carcinoma (SCC is less clear. Several studies have shown that human SCCs harbour unique mutations in the p53 gene as well as inactivation of the CDKN2A gene. While mutations in the p53 gene are induced by UV radiation and represent tumor initiating events, the majority of alterations detected in the CDKN2A gene do not appear to be UV-dependent. In conclusion, in addition to p53 mutations, silencing of the CDKN2A gene might play a significant role in SCC development.

  2. Aberrations of the p53 pathway components p53, MDM2 and CDKN2A appear independent in diffuse large B cell lymphoma

    DEFF Research Database (Denmark)

    Møller, Michael Boe; Ino, Y; Gerdes, A M;

    1999-01-01

    hypermethylated at the 5' CpG island of p16. No point mutations were found in CDKN2B or CDKN2A. Immunohistochemical staining of formalin-fixed, paraffin-embedded tissue for p16 confirmed these results, as all tumours with alterations of CDKN2A were p16 immunonegative. We found p53 mutations in eight (22%) cases...

  3. Germline CDKN2A/ARF alterations in human melanoma

    OpenAIRE

    Hashemi, Jamileh

    2002-01-01

    Approximately 10% of cases of human cutaneous malignant melanoma (CMM) have been estimated to occur in individuals with a familial predisposition, frequently in association with dysplastic nevus syndrome (DNS). The genetics of familial melanoma is complex and heterogeneous. To date only two melanoma predisposing genes have been identified. The CDKN2A/ARF locus on human chromosome 9p21 encodes two distinct cell cycle regulatory proteins, p16 and p14ARF. Germline alterations i...

  4. Genotyping of BRCA1, BRCA2, p53, CDKN2A, MLH1 and MSH2 genes in a male patient with secondary breast cancer

    International Nuclear Information System (INIS)

    Some tumour suppressor genes (BRCA2) and mismatch repair genes (MSH2, MLH1) are correlated with an increased risk for male breast cancer. Our patient developed secondary breast cancer after the treatment for Hodgkin’s disease in childhood. DNA was isolated from the patients’ blood and screened for mutations, polymorphisms and variants in BRCA1, BRCA2, p53, CDKN2A, MLH1 and MSH2 genes. We found no mutations but common polymorphisms, and three variants in mismatch repair genes. Nucleotide variants c.2006-6T>C and p.G322D in MSH2 might be correlated with male breast cancer

  5. p53 protein alterations in adult astrocytic tumors and oligodendrogliomas

    Directory of Open Access Journals (Sweden)

    Nayak Anupma

    2004-04-01

    Full Text Available BACKGROUND: p53 is a tumor suppressor gene implicated in the genesis of a variety of malignancies including brain tumors. Overexpression of the p53 protein is often used as a surrogate indicator of alterations in the p53 gene. AIMS: In this study, data is presented on p53 protein expression in adult cases (>15 years of age of astrocytic (n=152 and oligodendroglial (n=28 tumors of all grades. Of the astrocytic tumors, 86% were supratentorial in location while remaining 14% were located infratentorially - 8 in the the cerebellum and 13 in the brainstem. All the oligodendrogliomas were supratentorial. MATERIALS AND METHODS: p53 protein expression was evaluated on formalin-fixed paraffin-embedded sections using streptavidin biotin immunoperoxidase technique after high temperature antigen retrieval. RESULTS: Overall 52% of supratentorial astrocytic tumors showed p53 immunopositivity with no correlation to the histological grade. Thus, 58.8% of diffuse astrocytomas (WHO Grade II, 53.8% of anaplastic astrocytomas (WHO Grade III and 50% of glioblastomas (WHO Grade IV were p53 protein positive. In contrast, all the infratentorial tumors were p53 negative except for one brainstem glioblastoma. Similarly, pilocytic astrocytomas were uniformly p53 negative irrespective of the location. Among oligodendroglial tumors, the overall frequency of p53 immunopositivity was lower (only 28%, though a trend of positive correlation with the tumor grade was noted - 25% in Grade II and 31.5% in grade III (anaplastic oligodendroglioma. Interestingly, p53 labeling index (p53 LI did not correlate with the histopathological grade in both astrocytic and oligodendroglial tumors. CONCLUSIONS: Thus, this study gives an insight into the genetic and hence biological heterogeneity of gliomas, not only between astrocytic tumors vs. oligodendrogliomas but also within astrocytic tumors with regard to their grade and location. With p53 gene therapy trials in progress, this will

  6. G-actin guides p53 nuclear transport: potential contribution of monomeric actin in altered localization of mutant p53

    Science.gov (United States)

    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

  7. G-actin guides p53 nuclear transport: potential contribution of monomeric actin in altered localization of mutant p53.

    Science.gov (United States)

    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

  8. Alterations of the tumor suppressor genes CDKN2A (p16(INK4a)), p14(ARF), CDKN2B (p15(INK4b)), and CDKN2C (p18(INK4c)) in atypical and anaplastic meningiomas.

    Science.gov (United States)

    Boström, J; Meyer-Puttlitz, B; Wolter, M; Blaschke, B; Weber, R G; Lichter, P; Ichimura, K; Collins, V P; Reifenberger, G

    2001-08-01

    We investigated 67 meningothelial tumors (20 benign meningiomas, 34 atypical meningiomas, and 13 anaplastic meningiomas) for losses of genetic information from chromosome arms 1p and 9p, as well as for deletion, mutation, and expression of the tumor suppressor genes CDKN2A (p16(INKa)/MTS1), p14(ARF), CDKN2B (p15(INK4b)/MTS2) (all located at 9p21) and CDKN2C (1p32). Comparative genomic hybridization and microsatellite analysis showed losses on 1p in 11 anaplastic meningiomas (85%), 23 atypical meningiomas (68%), and 5 benign meningiomas (25%). One atypical meningioma with loss of heterozygosity on 1p carried a somatic CDKN2C mutation (c.202C>T: R68X). Losses on 9p were found in five anaplastic meningiomas (38%), six atypical meningiomas (18%), and one benign meningioma (5%). Six anaplastic meningiomas (46%) and one atypical meningioma (3%) showed homozygous deletions of the CDKN2A, p14(ARF), and CDKN2B genes. Two anaplastic meningiomas carried somatic point mutations in CDKN2A (c.262G>T: E88X and c.262G>A: E88K) and p14(ARF) (c.305G>T: G102V and c.305G>A: G102E). One anaplastic meningioma, three atypical meningiomas, and one benign meningioma without a demonstrated homozygous deletion or mutation of CDKN2A, p14(ARF), or CDKN2B lacked detectable transcripts from at least one of these genes. Hypermethylation of CDKN2A, p14(ARF), and CDKN2B could be demonstrated in one of these cases. Taken together, our results indicate that CDKN2C is rarely altered in meningiomas. However, the majority of anaplastic meningiomas either show homozygous deletions of CDKN2A, p14(ARF), and CDKN2B, mutations in CDKN2A and p14(ARF), or lack of expression of one or more of these genes. Thus, inactivation of the G(1)/S-phase cell-cycle checkpoint is an important aberration in anaplastic meningiomas. PMID:11485924

  9. Aging-Associated Truncated Form of p53 Interacts with Wild-Type p53 and Alters p53 Stability, Localization, and Activity

    OpenAIRE

    Moore, Lynette; Lu, Xiongbin; Ghebranious, Nader; Tyner, Stuart; Donehower, Lawrence A.

    2007-01-01

    Evidence has accumulated that p53, a prototypical tumor suppressor, may also influence aspects of organismal aging. We have previously described a p53 mutant mouse model, the p53+/m mouse, which is cancer resistant yet exhibits reduced longevity and premature aging phenotypes. p53+/m mice express one full length p53 allele and one truncated p53 allele that is translated into a C-terminal fragment of p53 termed the M protein. The augmented cancer resistance and premature aging phenotypes in th...

  10. p53 alteration in morphologically normal/benign breast tissue in patients with triple-negative high-grade breast carcinomas: breast p53 signature?

    Science.gov (United States)

    Wang, Xi; Stolla, Moritz; Ring, Brian Z; Yang, Qi; Laughlin, Todd S; Rothberg, Paul G; Skinner, Kristin; Hicks, David G

    2016-09-01

    p53 alterations have been identified in approximately 23% of breast carcinomas, particularly in hormone receptor-negative high-grade carcinomas. It is considered to be an early event in breast carcinogenesis. Nevertheless, the putative precursor lesion of high-grade breast carcinoma remains elusive. Breast excision specimens from 93 triple-negative high-grade invasive ductal carcinomas, 48 estrogen receptor (ER)-positive/progesterone receptor-positive/Her2-negative non-high-grade invasive ductal carcinomas, and 50 mammoplasty breasts were selected. At least 2 tissue blocks with tumor and adjacent benign tissue were sectioned and subjected to immunohistochemistry staining for p53. TP53 gene sequencing was performed on select tumors. Further immunohistochemistry staining for ER and Ki-67 was performed on consecutive sections of tissue with p53-positive normal/benign cells. Of the 93 high-grade carcinomas, 51 (55%) were positive for p53 alteration, whereas only 3 (6.25%) of the 48 non-high-grade carcinomas were p53 altered. Focal p53 positivity in adjacent normal/benign breast tissue was identified in 19 cases, and 18 of them also had p53 alteration in their carcinomas. Only 1 case had focal p53 staining in normal/benign tissue, but the tumor was negative for p53 alteration. No p53 staining positivity was identified in the mammoplasty specimens. The p53-stained normal/benign cells were ER negative and did not show an increase in the Ki-67 labeling index. These findings indicate that the p53 staining positivity in normal/benign breast tissue is not a random event. It could be considered as the "p53 signature" in breast and serve as an indicator for future potential risk of p53-positive high-grade breast carcinoma. PMID:27246177

  11. p53 Alterations in Human Skin : A Molecular Study Based on Morphology

    OpenAIRE

    Gao, Ling

    2001-01-01

    Mutation of the p53 gene appears to be an early event in skin cancer development. The present study is based on morphology and represents a cellular and genetic investigation of p53 alterations in normal human skin and basal cell cancer. Using double immunofluorescent labelling, we have demonstrated an increase in thymine dimers and p53 protein expression in the same keratinocytes following ultraviolet radiation. Large inter-individual differences in the kinetics of thymine dimer repair and ...

  12. Skin human papillomavirus type 38 alters p53 functions by accumulation of ΔNp73

    OpenAIRE

    Accardi, Rosita; Dong, Wen; Smet, Anouk; Cui, Rutao; Hautefeuille, Agnes; Gabet, Anne-Sophie; Sylla, Bakary S.; Gissmann, Lutz; Hainaut, Pierre; Tommasino, Massimo

    2006-01-01

    The E6 and E7 of the cutaneous human papillomavirus (HPV) type 38 immortalize primary human keratinocytes, an event normally associated with the inactivation of pathways controlled by the tumour suppressor p53. Here, we show for the first time that HPV38 alters p53 functions. Expression of HPV38 E6 and E7 in human keratinocytes or in the skin of transgenic mice induces stabilization of wild-type p53. This selectively activates the transcription of ΔNp73, an isoform of the p53-related protein ...

  13. Alterations in tumour suppressor gene p53 in human gliomas from Indian patients

    Indian Academy of Sciences (India)

    Pornima Phatak; S Kalai Selvi; T Divya; A S Hegde; Sridevi Hegde; Kumaravel Somasundaram

    2002-12-01

    Alterations in the tumour suppressor p53 gene are among the most common defects seen in a variety of human cancers. In order to study the significance of the p53 gene in the genesis and development of human glioma from Indian patients, we checked 44 untreated primary gliomas for mutations in exons 5–9 of the p53 gene by PCR-SSCP and DNA sequencing. Sequencing analysis revealed six missense mutations. The incidence of p53 mutations was 13.6% (6 of 44). All the six mutations were found to be located in the central core domain of p53, which carries the sequence-specific DNA-binding domain. These results suggest a rather low incidence but a definite involvement of p53 mutations in the gliomas of Indian patients.

  14. Altered microRNA Expression Profiles and Regulation of INK4A/CDKN2A Tumor Suppressor Genes in Canine Breast Cancer Models.

    Science.gov (United States)

    Lutful Kabir, Farruk Mohammad; DeInnocentes, Patricia; Bird, Richard Curtis

    2015-12-01

    microRNA (miRNA) expression profiling of cancer versus normal cells may reveal the characteristic regulatory features that can be correlated to altered gene expression in both human and animal models of cancers. In this study, the comprehensive expression profiles of the 277 highly characterized miRNAs from the canine genome were evaluated in spontaneous canine mammary tumor (CMT) models harboring defects in a group of cell cycle regulatory and potent tumor suppressor genes of INK4/CDKN2 family including p16/INK4A, p14ARF, and p15/INK4B. A large number of differentially expressed miRNAs were identified in three CMT cell lines to potentially target oncogenes, tumor suppressor genes and cancer biomarkers. A group of the altered miRNAs were identified by miRNA target prediction tools for regulation of the INK4/CDKN2 family tumor suppressor genes. miRNA-141 was experimentally validated for INK4A 3'-UTR target binding in the CMT cell lines providing an essential mechanism for the post-transcriptional regulation of the INK4A tumor suppressor gene in CMT models. A well-recognized group of miRNAs including miR-21, miR-155, miR-9, miR-34a, miR-143/145, and miR-31 were found to be altered in both CMTs and human breast cancer. These altered miRNAs might serve as potential targets for advancing the development of future therapeutic reagents. These findings further strengthen the validity and use of canine breast cancers as appropriate models for the study of human breast cancers. PMID:26095675

  15. Skin human papillomavirus type 38 alters p53 functions by accumulation of ΔNp73

    Science.gov (United States)

    Accardi, Rosita; Dong, Wen; Smet, Anouk; Cui, Rutao; Hautefeuille, Agnes; Gabet, Anne-Sophie; Sylla, Bakary S; Gissmann, Lutz; Hainaut, Pierre; Tommasino, Massimo

    2006-01-01

    The E6 and E7 of the cutaneous human papillomavirus (HPV) type 38 immortalize primary human keratinocytes, an event normally associated with the inactivation of pathways controlled by the tumour suppressor p53. Here, we show for the first time that HPV38 alters p53 functions. Expression of HPV38 E6 and E7 in human keratinocytes or in the skin of transgenic mice induces stabilization of wild-type p53. This selectively activates the transcription of ΔNp73, an isoform of the p53-related protein p73, which in turn inhibits the capacity of p53 to induce the transcription of genes involved in growth suppression and apoptosis. ΔNp73 downregulation by an antisense oligonucleotide leads to transcriptional re-activation of p53-regulated genes and apoptosis. Our findings illustrate a novel mechanism of the alteration of p53 function that is mediated by a cutaneous HPV type and support the role of HPV38 and ΔNp73 in human carcinogenesis. PMID:16397624

  16. Skin human papillomavirus type 38 alters p53 functions by accumulation of deltaNp73.

    Science.gov (United States)

    Accardi, Rosita; Dong, Wen; Smet, Anouk; Cui, Rutao; Hautefeuille, Agnes; Gabet, Anne-Sophie; Sylla, Bakary S; Gissmann, Lutz; Hainaut, Pierre; Tommasino, Massimo

    2006-03-01

    The E6 and E7 of the cutaneous human papillomavirus (HPV) type 38 immortalize primary human keratinocytes, an event normally associated with the inactivation of pathways controlled by the tumour suppressor p53. Here, we show for the first time that HPV38 alters p53 functions. Expression of HPV38 E6 and E7 in human keratinocytes or in the skin of transgenic mice induces stabilization of wild-type p53. This selectively activates the transcription of deltaNp73, an isoform of the p53-related protein p73, which in turn inhibits the capacity of p53 to induce the transcription of genes involved in growth suppression and apoptosis. DeltaNp73 downregulation by an antisense oligonucleotide leads to transcriptional re-activation of p53-regulated genes and apoptosis. Our findings illustrate a novel mechanism of the alteration of p53 function that is mediated by a cutaneous HPV type and support the role of HPV38 and deltaNp73 in human carcinogenesis. PMID:16397624

  17. Anal cancer in Chinese: human papillomavirus infection and altered expression of p53

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    AIM To detect the presence of HPV DNA and study the alteration of p53 expression in anal cancers in Chinese.METHODS HPV DNA was amplified by PCR. The amplified HPV DNA was classified by DBH. HPV antigen and p53 expression were respectively detected by immunohistochemistry.RESULTS HPV DNA was amplified only in one case of squamous cell carcinoma of the 72 Chinese anal cancers and further classified as HPV type 16. Others were all HPV negative. HPV antigen and p53 expression were also detected in this case. Positive stainings with anti-p53 antibody were seen in 61.2% anal cancers. There were no statistically significant differences between anal squamous cell carcinomas and adenocarcinomas and between anal adenocarcinomas and rectal adenocarcinomas. p53 protein expression was observed in the basal cells of squamous epithelium of condyloma acuminatum and morphologically normal squamous epithelium in 2 cases invaded by anal adenocarcinoma.CONCLUSION HPV infection was not associated with these cases of anal cancer. p53 alteration was a common event. Positive p53 immunostaining can not be regarded as a marker for differentiating benign from malignant lesions.

  18. Resetting the histone code at CDKN2A in HNSCC by inhibition of DNA methylation.

    Science.gov (United States)

    Coombes, Madelene M; Briggs, Katrina L; Bone, James R; Clayman, Gary L; El-Naggar, Adel K; Dent, Sharon Y R

    2003-12-01

    Head and neck squamous cell carcinoma (HNSCC) is the fifth most frequent cancer in the US. Several genetic and epigenetic alterations are associated with HNSCC tumorigenesis, including inactivation of CDKN2A, which encodes the p16 tumor suppressor, in cell lines and primary tumors by DNA methylation. Reactivation of tumor suppressor genes by DNA-demethylating agents and histone deacetylase (HDAC) inhibitors shows therapeutic promise for other cancers. Therefore, we investigated the ability of these agents to reactivate p16 in Tu159 HNSCC cells. Treatment of cells with 5-aza-2'deoxycytidine (5-aza-dC) increases CDKN2A expression and slightly increases histone H3 acetylation at this gene. No reactivation of CDKN2A is observed upon treatment with the HDAC inhibitor trichostatin A (TSA), but synergistic reactivation of CDKN2A is observed upon sequential treatment of Tu159 cells with both 5-aza-dC and TSA. Silencing of CDKN2A in Tu159 cells is correlated with increased methylation of histone H3 at lysine 9 and decreased methylation at lysine 4 relative to the upstream p15 gene promoter. Interestingly, global levels of H3-K9 methylation are decreased upon treatment with 5-aza-dC. Together these data indicate that DNA methylation is a dominant epigenetic mark for silencing of CDKN2A in Tu159 tumor cells. Moreover, changes in DNA methylation can reset the histone code by impacting multiple H3 modifications. PMID:14654786

  19. Alteration of p53and p21 during hepatocarcinogenesis in shrews

    Institute of Scientific and Technical Information of China (English)

    Jian-Jia Su; Rui-Qi Yang; Ke-Chen Ban; Yuan Li; Liu-Liang Qin; Hui-Yun Wang; Chun Yang; Chao Ou; Xiao-Xian Duan; Young-Lk Lee

    2004-01-01

    development exists between HBV and AFB1. p53 mutation promotes the development of HCC. HBV and AFB1 may synergistically induce p53 gene mutation, and stimulate fas gene expression. fas gene is activated at the earlier stage during hepatocarcinogenesis. p21 protein may be an early marker, and the alterations of p53 may be a late event in the development of HCC.

  20. Alcohol alters hepatic FoxO1, p53, and mitochondrial SIRT5 deacetylation function

    International Nuclear Information System (INIS)

    Chronic alcohol consumption affects the gene expression of a NAD-dependent deacetylase Sirtuis 1 (SIRT1) and the peroxisome proliferator-activated receptor-γ coactivator1α (PGC-1α). Our aim was to verify that it also alters the forkhead (FoxO1) and p53 transcription factor proteins, critical in the hepatic response to oxidative stress and regulated by SIRT1 through its deacetylating capacity. Accordingly, rats were pair-fed the Lieber-DeCarli alcohol-containing liquid diets for 28 days. Alcohol increased hepatic mRNA expression of FoxO1 (p = 0.003) and p53 (p = 0.001) while corresponding protein levels remained unchanged. However phospho-FoxO1 and phospho-Akt (protein kinase) were both decreased by alcohol consumption (p = 0.04 and p = 0.02, respectively) while hepatic p53 was found hyperacetylated (p = 0.017). Furthermore, mitochondrial SIRT5 was reduced (p = 0.0025), and PGC-1α hyperacetylated (p = 0.027), establishing their role in protein modification. Thus, alcohol consumption disrupts nuclear-mitochondrial interactions by post-translation protein modifications, which contribute to alteration of mitochondrial biogenesis through the newly discovered reduction of SIRT5

  1. Frequent alteration of MDM2 and p53 in the molecular progression of recurring non-Hodgkin's lymphoma

    DEFF Research Database (Denmark)

    Møller, Michael Boe; Nielsen, O; Pedersen, Niels Tinggaard

    2002-01-01

    -Hodgkin's lymphoma. METHODS AND RESULTS: We have analysed sequential biopsies from 42 non-Hodgkin's lymphoma patients immunohistochemically for p53 alterations (based on p53 and p21Waf1 expression), as well as for expression of MDM2, p27Kip1 and cyclin D3. Relapse of follicle centre lymphoma was associated with p53...... alterations as 5/6 (83%) follicle centre lymphomas with normal p53 at diagnosis showed p53 alterations at relapse. Of these cases, three showed transformation to diffuse large B-cell lymphoma. p53 alteration was also associated with relapse of de novo diffuse large B-cell lymphoma and T-cell non......-Hodgkin's lymphoma, as 2/5 (40%) diffuse large B-cell lymphomas and 3/9 (33%) T-cell non-Hodgkin's lymphomas with normal p53 at diagnosis showed p53 alterations at relapse. No indolent non-Hodgkin's lymphoma case showed MDM2 over-expression at diagnosis, whereas 4/5 (80%) transformed diffuse large B-cell lymphomas...

  2. Correlation of p53 over-expression and alteration in p53 gene detected by polymerase chain reaction-single strand conformation polymorphism in adenocarcinoma of gastric cancer patients from India

    Institute of Scientific and Technical Information of China (English)

    Sajjad Karim; Arif Ali

    2009-01-01

    AIM: To study the alterations in p53 gene among Indian gastric cancer patients and to correlate them with the various clinicopathological parameters.METHODS: A total of 103 gastric cancer patients were included in this study. The p53 alterations were studied by both immunohistochemical method as well as polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis. We only studied four (exon 5, 6, 7, and 8) of the 11 p53 exons. The alterations in p53 were also correlated with respect to various clinicopathological parameters.RESULTS: Among 103 cases, p53 over-expression and alteration were detected in 37 (35.92%) and 19 (18.44%) cases, respectively. Most of the p53 alterations were found at exon 5 (31.54%), followed by exon 6 (26.31%), exon 7 (21.04%) and exon 8 (21.04%). A significant correlation of p53 overexpression was found with p53 alteration ( P = 0.000).Concordance between p53 alteration (as detected by SSCP) and over-expression [as detected by immunohistochemistry (IHC)] was found in 75% cases.We found that IHC-positive/SSCP-negative cases accounted for 21% of cases and IHC-negative/SSCPpositive cases accounted for remaining 4% cases.CONCLUSION: Our results show that p53 gene mutations are significantly correlated with p53 protein over-expression, with 75% concordance in overexpression and alteration in the p53 gene, but 25% disconcordance also cautions against the assumption that p53 over-expression is always associated with a gene mutation. There may be other mechanisms responsible for stabilization and accumulation of p53 protein with no evidence of gene mutation that reflect an accumulation of a non-mutated protein, or a false negative SSCP result.

  3. Phosphorylation at Ser-15 and Ser-392 in mutant p53 molecules from human tumors is altered compared to wild-type p53.

    OpenAIRE

    Ullrich, S J; K. Sakaguchi; Lees-Miller, S P; Fiscella, M.; Mercer, W E; Anderson, C W; Appella, E

    1993-01-01

    The product of the p53 gene suppresses cell growth and plays a critical role in suppressing development of human tumors. p53 protein binds DNA, activates transcription, and can be phosphorylated at N- and C-terminal sites. Previously, wild-type p53 was shown to be hyperphosphorylated compared to mutant p53 during p53-mediated growth arrest in vivo. Here we show that Ser-15 and Ser-9 in the N-terminal transactivation domain of wild-type human p53 are phosphorylated in vivo in cells derived fro...

  4. Mutant p53 proteins alter cancer cell secretome and tumour microenvironment: Involvement in cancer invasion and metastasis.

    Science.gov (United States)

    Cordani, Marco; Pacchiana, Raffaella; Butera, Giovanna; D'Orazi, Gabriella; Scarpa, Aldo; Donadelli, Massimo

    2016-07-01

    An ever-increasing number of studies highlight the role of mutant p53 proteins in the alteration of cancer cell secretome and in the modification of tumour microenvironment, sustaining an invasive phenotype of cancer cell. The knowledge of the molecular mechanisms underlying the interplay between mutant p53 proteins and the microenvironment is becoming fundamental for the identification of both efficient anticancer therapeutic strategies and novel serum biomarkers. In this review, we summarize the novel findings concerning the regulation of secreted molecules by cancer cells bearing mutant TP53 gene. In particular, we highlight data from available literature, suggesting that mutant p53 proteins are able to (i) alter the secretion of enzymes involved in the modulation of extracellular matrix components; (ii) alter the secretion of inflammatory cytokines; (iii) increase the extracellular acidification; and (iv) regulate the crosstalk between cancer and stromal cells. PMID:27045472

  5. Pharmacological activation of wild-type p53 in the therapy of leukemia.

    Science.gov (United States)

    Kojima, Kensuke; Ishizawa, Jo; Andreeff, Michael

    2016-09-01

    The tumor suppressor p53 is inactivated by mutations in the majority of human solid tumors. Conversely, p53 mutations are rare in leukemias and are only observed in a small fraction of the patient population, predominately in patients with complex karyotype acute myeloid leukemia or hypodiploid acute lymphoblastic leukemia. However, the loss of p53 function in leukemic cells is often caused by abnormalities in p53-regulatory proteins, including overexpression of MDM2/MDMX, deletion of CDKN2A/ARF, and alterations in ATM. For example, MDM2 inhibits p53-mediated transcription, promotes its nuclear export, and induces proteasome-dependent degradation. The MDM2 homolog MDMX is another direct regulator of p53 that inhibits p53-mediated transcription. Several small-molecule inhibitors and stapled peptides targeting MDM2 and MDMX have been developed and have recently entered clinical trials. The clinical trial results of the first clinically used MDM2 inhibitor, RG7112, illustrated promising p53 activation and apoptosis induction in leukemia cells as proof of concept. Side effects of RG7112 were most prominent in suppression of thrombopoiesis and gastrointestinal symptoms in leukemia patients. Predictive biomarkers for response to MDM2 inhibitors have been proposed, but they require further validation both in vitro and in vivo so that the accumulated knowledge concerning pathological p53 dysregulation in leukemia and novel molecular-targeted strategies to overcome this dysregulation can be translated safely and efficiently into novel clinical therapeutics. PMID:27327543

  6. Differential regulation and synthetic lethality of exclusive RB1 and CDKN2A mutations in lung cancer.

    Science.gov (United States)

    Kim, Nayoung; Song, Mee; Kim, Somin; Seo, Yujeong; Kim, Yonghwan; Yoon, Sukjoon

    2016-01-01

    Genetic alterations in lung cancer are distinctly represented in non-small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC). Mutation of the RB1 and CDKN2A genes, which are tightly associated with cell cycle regulation, is exclusive to SCLC and NSCLC cells, respectively. Through the systematic analysis of transcriptome and proteome datasets for 318 cancer cell lines, we characterized differential gene expression and protein regulation in RB1-mutant SCLC and CDKN2A-mutant NSCLC. Many of the genes and proteins associated with RB1-mutant SCLC cell lines belong to functional categories of gene expression and transcription, whereas those associated with CDKN2A-mutant NSCLC cell lines were enriched in gene sets of the extracellular matrix and focal adhesion. These results indicate that the loss of RB1 and CDKN2A function induces distinctively different signaling cascades in SCLC and NSCLC cells. In addition, knockdown of the RB1 gene in CKDN2A-mutant cell lines (and vice versa) synergistically inhibits cancer cell proliferation. The present study on the exclusive role of RB1 and CDKN2A mutations in lung cancer subtypes demonstrates a synthetic lethal strategy for cancer regulation. PMID:26647789

  7. Loss of CDKN2A Promoter Methylation Coincides With the Epigenetic Transdifferentiation of Uterine Myosarcomatous Cells.

    Science.gov (United States)

    Roncati, Luca; Barbolini, Giuseppe; Sartori, Giuliana; Siopis, Elena; Pusiol, Teresa; Maiorana, Antonio

    2016-07-01

    Leiomyosarcoma is the most common type of uterine sarcoma and usually displays typical morphology. Heterologous leiomyosarcoma is the rarest variant, in which the tumor contains liposarcomatous, osteosarcomatous, or rhabdomyosarcomatous components. We have investigated the largest series of uterine leiomyosarcoma with a rhabdomyosarcomatous component and we have disclosed a molecular finding, which coincides to the process of transdifferentiation from smooth muscle into striated muscle phenotype. The surgical specimens of 5 rare cases of uterine leiomyosarcoma with a rhabdomyosarcomatous component were formalin fixed and paraffin embedded. In addition to hematoxylin/eosin stains, phosphotungstic acid hematoxylin staining, immunohistochemistry, and methylation-specific polymerase chain reaction the CDKN2A promoter region were performed. Leiomyosarcomatous cells were found to be strongly immunoreactive for both desmin and α-smooth muscle actin. Rhabdomyosarcomatous cells were immunoreactive for sarcomeric actin, desmin, vimentin, CD10, and p16. The methylation-specific polymerase chain reaction revealed the presence of a methylated allele and an unmethylated allele in the microdissected samples, coming from leiomyosarcomatous cells. On the contrary, 2 unmethylated alleles, molecular expression of a loss of heterozygosity, were detected in all the microdissected samples in the rhabdomyosarcomatous cells. The loss of heterozygosity methylation in the promoter region of the CDKN2A gene, occurred only in the rhabdomyosarcomatous cells with increases in both p16 and p14 expression. This event may result in an inhibition of cdk4/cdk6 activity, stabilizes the tumor suppressor protein p53, and coincides with the transdifferentiation from smooth muscle into striated muscle. PMID:27276112

  8. Topical formulation engendered alteration in p53 and cyclobutane pyrimidine dimer expression in chronic photodamaged patients.

    Science.gov (United States)

    Spencer, James M; Morgan, Michael B; Trapp, Kara M; Moon, Summer D

    2013-03-01

    While the clinical attributes of photoaging are well characterized in the literature, the pathogenic mechanisms that underlie these changes are incompletely elucidated. At the molecular level, p53 tumor-suppressor gene product mediated excision repair of ultraviolet (UV)-induced DNA damage is a critical effector in xeroderma pigmentosum (XP) and potentially in conventional photoaging. We examined p53 activity and measured UV-induced DNA damage via cyclobutane pyrimidine dimers (CPDs) quantitatively in 20 volunteers before and after an 8-week, open-label prospective topical application of a proprietary DNA recovery serum (Celfix). There was a statistically significant decrease in immunohistochemically determined p53 and CPD levels. While these data are preliminary, the findings lend support to the theoretical possibility of a topical agent reversing the effects of photodamage at the molecular level and, potentially, an ameliorative outcome clinically. PMID:23545918

  9. Indication for CDKN2A-mutation analysis in familial pancreatic cancer families without melanomas

    NARCIS (Netherlands)

    Harinck, Femme; Kluijt, Irma; van der Stoep, Nienke; Oldenburg, Rogier A.; Wagner, Anja; Aalfs, Cora M.; Sijmons, Rolf H.; Poley, Jan-Werner; Kuipers, Ernst J.; Fockens, Paul; van Os, Theo A. M.; Bruno, Marco J.

    2012-01-01

    Background CDKN2A-mutation carriers run a high risk of developing melanomas and have an increased risk of developing pancreatic cancer (PC). Familial PC (FPC) patients with a personal history or family history of melanomas are therefore offered CDKN2A-mutation analysis. In contrast, CDKN2A testing i

  10. Mutant p53 uses p63 as a molecular chaperone to alter gene expression and induce a pro-invasive secretome

    OpenAIRE

    Paul M. Neilsen; Noll, Jacqueline E.; Suetani, Rachel J; Schulz, Renee B.; Al-Ejeh, Fares; Evdokiou, Andreas; Lane, David P; David F. Callen

    2011-01-01

    Mutations in the TP53 gene commonly result in the expression of a full-length protein that drives cancer cell invasion and metastasis. Herein, we have deciphered the global landscape of transcriptional regulation by mutant p53 through the application of a panel of isogenic H1299 derivatives with inducible expression of several common cancer-associated p53 mutants. We found that the ability of mutant p53 to alter the transcriptional profile of cancer cells is remarkably conserved across differ...

  11. The cytoskeleton adaptor protein ankyrin-1 is upregulated by p53 following DNA damage and alters cell migration.

    Science.gov (United States)

    Hall, A E; Lu, W-T; Godfrey, J D; Antonov, A V; Paicu, C; Moxon, S; Dalmay, T; Wilczynska, A; Muller, P A J; Bushell, M

    2016-01-01

    The integrity of the genome is maintained by a host of surveillance and repair mechanisms that are pivotal for cellular function. The tumour suppressor protein p53 is a major component of the DNA damage response pathway and plays a vital role in the maintenance of cell-cycle checkpoints. Here we show that a microRNA, miR-486, and its host gene ankyrin-1 (ANK1) are induced by p53 following DNA damage. Strikingly, the cytoskeleton adaptor protein ankyrin-1 was induced over 80-fold following DNA damage. ANK1 is upregulated in response to a variety of DNA damage agents in a range of cell types. We demonstrate that miR-486-5p is involved in controlling G1/S transition following DNA damage, whereas the induction of the ankyrin-1 protein alters the structure of the actin cytoskeleton and sustains limited cell migration during DNA damage. Importantly, we found that higher ANK1 expression correlates with decreased survival in cancer patients. Thus, these observations highlight ANK1 as an important effector downstream of the p53 pathway. PMID:27054339

  12. Acute ammonia neurotoxicity in vivo involves increase in cytoplasmic protein P53 without alterations in other markers of apoptosis.

    Science.gov (United States)

    Kosenko, Elena; Kaminsky, Yuri; Solomadin, Ilia; Marov, Nikolay; Venediktova, Natalia; Felipo, Vicente; Montoliu, Carmina

    2007-08-15

    Acute intoxication with large ammonia doses leads to activation of NMDA receptors in the brain, resulting in oxidative stress and disturbance of mitochondrial function. Altered mitochondrial function is a crucial step in some mechanisms of cellular apoptosis. This study assesses whether ammonia intoxication in vivo leads to induction of apoptotic markers such as permeability transition pore (PTP) formation, caspase-3, and caspase-9 activation, changes in p53 protein, or cytochrome c release. Acute ammonia intoxication did not affect caspase-9 or caspase-3 activities. The mitochondrial membrane potential also remained unaltered in non-synaptic brain mitochondria after injection of ammonia, indicating that ammonia did not induce PTP formation in brain in vivo. The nuclear level of p53 did not change, whereas its cytoplasmic level increased approximately two-fold. In agreement with the theory that translocation of the p53 from cytosol to nuclei is an essential step for induction of apoptosis we did not find apoptotic nuclei in brain of rats injected with ammonia. This supports the idea that ammonia neurotoxicity does not involve apoptosis and points to impaired p53 transfer from cytoplasm to nuclei as a possible preventer of apoptosis. We did not find any release of cytochrome c from mitochondria to cytosol after ammonia injection. Cytochrome c content was significantly reduced (30%) in brain mitochondria from rats injected with ammonia. This decrease may contribute to the reduced state 3 respiration, decreased respiratory control index, and disturbances in the mitochondrial electron transport chain in brain mitochondria from rats injected with ammonia. PMID:17551980

  13. p53 isoforms change p53 paradigm

    OpenAIRE

    Bourdon, JC

    2014-01-01

    Although p53 defines cellular responses to cancer treatment it is not clear how p53 can be used to control cell fate outcome. Data demonstrate that so-called p53 does not exist as a single protein, but is in fact a group of p53 protein isoforms whose expression can be manipulated to control the cellular response to treatment.

  14. Molecular biologic study about the non-small cell lung carcinoma (2) : p53 gene alteration in non-small cell lung carcinoma

    International Nuclear Information System (INIS)

    The main purpose of this research was to identify of the p53 and 3p gene alteration in non-small cell lung cancer patients residing in Korea. Furthermore, we analyzed the relationship between the p53 and 3p gene alterations and the clinicopathologic results of lung cancer patients. And we have investigated the role of PCR-LOH in analyzing tumor samples for LOH of defined chromosomal loci. We have used the 40 samples obtained from the lung cancer patients who were diagnosed and operated curatively at Korea Cancer Center Hospital. We have isolated the high molecular weight. DNA from the tumors and normal tissues. And we have amplified the DNA with PCR method and used the microsatellite assay method to detect the altered p53 and 3p gene. The conclusions were as follow: 1) The 3p gene alteration was observed in 9/39 (23.1%) and p53 gene alteration was observed in 15/40 (37.5%) of resected non-small cell lung cancer. 2) There was no correlations between the 3p or p53 gene alterations and prognosis of patients, but further study is necessary. 3) PCR-LOH is a very useful tool for analyzing small amount of tumor samples for loss of heterozygosity of defined chromosomal loci. (author). 10 refs

  15. CDKN2A and CDK4 mutation analysis in Italian melanoma-prone families: functional characterization of a novel CDKN2A germ line mutation

    OpenAIRE

    Torre, G Della; Pasini, B; S. Frigerio; Donghi, R; Rovini, D; Delia, D; Peters, G.; Huot, T J G; Bianchi-Scarra, G; Lantieri, F; Rodolfo, M.; Parmiani, G.; Pierotti, M A

    2001-01-01

    Physical interaction between CDKN2A/p16 and CDK4 proteins regulates the cell cycle progression through the G1 phase and dysfunction of these proteins by gene mutation is implicated in genetic predisposition to melanoma. We analysed 15 Italian melanoma families for germ line mutations in the coding region of the CDKN2A gene and exon 2 of the CDK4 gene. One novel disease-associated mutation (P48T), 3 known pathological mutations (R24P, G101W and N71S) and 2 common polymorphisms (A148T and Nt500...

  16. Losses of both products of the Cdkn2a/Arf locus contribute to asbestos-induced mesothelioma development and cooperate to accelerate tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Deborah A Altomare

    Full Text Available The CDKN2A/ARF locus encompasses overlapping tumor suppressor genes p16(INK4A and p14(ARF, which are frequently co-deleted in human malignant mesothelioma (MM. The importance of p16(INK4A loss in human cancer is well established, but the relative significance of p14(ARF loss has been debated. The tumor predisposition of mice singly deficient for either Ink4a or Arf, due to targeting of exons 1α or 1β, respectively, supports the idea that both play significant and nonredundant roles in suppressing spontaneous tumors. To further test this notion, we exposed Ink4a(+/- and Arf(+/- mice to asbestos, the major cause of MM. Asbestos-treated Ink4a(+/- and Arf(+/- mice showed increased incidence and shorter latency of MM relative to wild-type littermates. MMs from Ink4a(+/- mice exhibited biallelic inactivation of Ink4a, loss of Arf or p53 expression and frequent loss of p15(Ink4b. In contrast, MMs from Arf(+/- mice exhibited loss of Arf expression, but did not require loss of Ink4a or Ink4b. Mice doubly deficient for Ink4a and Arf, due to deletion of Cdkn2a/Arf exon 2, showed accelerated asbestos-induced MM formation relative to mice deficient for Ink4a or Arf alone, and MMs exhibited biallelic loss of both tumor suppressor genes. The tumor suppressor function of Arf in MM was p53-independent, since MMs with loss of Arf retained functional p53. Collectively, these in vivo data indicate that both CDKN2A/ARF gene products suppress asbestos carcinogenicity. Furthermore, while inactivation of Arf appears to be crucial for MM pathogenesis, the inactivation of both p16(Ink4a and p19(Arf cooperate to accelerate asbestos-induced tumorigenesis.

  17. Germline CDKN2A mutation implicated in predisposition to multiple myeloma.

    Science.gov (United States)

    Dilworth, D; Liu, L; Stewart, A K; Berenson, J R; Lassam, N; Hogg, D

    2000-03-01

    Germline mutations of the CDKN2A (p16(INK4A)) tumor suppressor gene predispose patients to melanoma and pancreatic carcinoma. In contrast, mutations of the murine CDKN2A gene predispose BALB/c mice to pristane-induced plasmacytoma. We describe here a family in which a germline mutation of CDKN2A is present in 4 individuals who developed melanoma as well as in a fifth family member who is suffering from multiple myeloma. To determine whether the CDKN2A mutation predisposed the myeloma patient to her disease, we carried out loss of heterozygosity studies on sorted bone marrow from this individual and observed loss of the wild type CDKN2A allele in the malignant plasma cells. We suggest that germline mutations of CDKN2A may predispose individuals to a wider variety of malignancy than has been hitherto reported, but that the expression of these cancers may depend heavily on the genetic background of the patient. (Blood. 2000;95:1869-1871) PMID:10688850

  18. Isocitrate dehydrogenase 1 mutations (IDH1) and p16/CDKN2A copy number change in conventional chondrosarcomas.

    OpenAIRE

    Amary, M. F.; Ye, H; Forbes, G.; Damato, S; Maggiani, F.; Pollock, R; Tirabosco, R.; Flanagan, A M

    2015-01-01

    To determine whether IDH1 mutations are present in primary and relapsed (local and distal) conventional central chondrosarcomas; and secondly, to assess if loss of p16/CDKN2A is associated with tumour grade progression, 102 tumour samples from 37 patients, including material from presenting and relapse events, were assessed. All wild-type cases for IDH1 R132 substitutions were also tested for IDH2 R172 and R140 alterations. The primary tumour and the most recent relapse sample were tested for...

  19. Neurodegeneration in Autoimmune Optic Neuritis Is Associated with Altered APP Cleavage in Neurons and Up-Regulation of p53.

    Directory of Open Access Journals (Sweden)

    Sabine Herold

    Full Text Available Multiple Sclerosis (MS is a chronic autoimmune inflammatory disease of the central nervous system (CNS. Histopathological and radiological analysis revealed that neurodegeneration occurs early in the disease course. However, the pathological mechanisms involved in neurodegeneration are poorly understood. Myelin oligodendrocyte glycoprotein (MOG-induced experimental autoimmune encephalomyelitis (EAE in Brown Norway rats (BN-rats is a well-established animal model, especially of the neurodegenerative aspects of MS. Previous studies in this animal model indicated that loss of retinal ganglion cells (RGCs, the neurons that form the axons of the optic nerve, occurs in the preclinical phase of the disease and is in part independent of overt histopathological changes of the optic nerve. Therefore, the aim of this study was to identify genes which are involved in neuronal cell loss at different disease stages of EAE. Furthermore, genes that are highly specific for autoimmune-driven neurodegeneration were compared to those regulated in RGCs after optic nerve axotomy at corresponding time points. Using laser capture micro dissection we isolated RNA from unfixed RGCs and performed global transcriptome analysis of retinal neurons. In total, we detected 582 genes sequentially expressed in the preclinical phase and 1150 genes in the clinical manifest EAE (P 1.5. Furthermore, using ingenuity pathway analysis (IPA, we identified amyloid precursor protein (APP as a potential upstream regulator of changes in gene expression in the preclinical EAE but neither in clinical EAE, nor at any time point after optic nerve transection. Therefore, the gene pathway analysis lead to the hypothesis that altered cleavage of APP in neurons in the preclinical phase of EAE leads to the enhanced production of APP intracellular domain (AICD, which in turn acts as a transcriptional regulator and thereby initiates an apoptotic signaling cascade via up-regulation of the target gene p

  20. Islet biology, the CDKN2A/B locus and type 2 diabetes risk.

    Science.gov (United States)

    Kong, Yahui; Sharma, Rohit B; Nwosu, Benjamin U; Alonso, Laura C

    2016-08-01

    Type 2 diabetes, fuelled by the obesity epidemic, is an escalating worldwide cause of personal hardship and public cost. Diabetes incidence increases with age, and many studies link the classic senescence and ageing protein p16(INK4A) to diabetes pathophysiology via pancreatic islet biology. Genome-wide association studies (GWASs) have unequivocally linked the CDKN2A/B locus, which encodes p16 inhibitor of cyclin-dependent kinase (p16(INK4A)) and three other gene products, p14 alternate reading frame (p14(ARF)), p15(INK4B) and antisense non-coding RNA in the INK4 locus (ANRIL), with human diabetes risk. However, the mechanism by which the CDKN2A/B locus influences diabetes risk remains uncertain. Here, we weigh the evidence that CDKN2A/B polymorphisms impact metabolic health via islet biology vs effects in other tissues. Structured in a bedside-to-bench-to-bedside approach, we begin with a summary of the evidence that the CDKN2A/B locus impacts diabetes risk and a brief review of the basic biology of CDKN2A/B gene products. The main emphasis of this work is an in-depth look at the nuanced roles that CDKN2A/B gene products and related proteins play in the regulation of beta cell mass, proliferation and insulin secretory function, as well as roles in other metabolic tissues. We finish with a synthesis of basic biology and clinical observations, incorporating human physiology data. We conclude that it is likely that the CDKN2A/B locus influences diabetes risk through both islet and non-islet mechanisms. PMID:27155872

  1. The P48T germline mutation and polymorphism in the CDKN2A gene of patients with melanoma

    Directory of Open Access Journals (Sweden)

    Huber J.

    2006-01-01

    Full Text Available CDKN2A has been implicated as a melanoma susceptibility gene in some kindreds with a family history of this disease. Mutations in CDKN2A may produce an imbalance between functional p16ink4a and cyclin D causing abnormal cell growth. We searched for germline mutations in this gene in 22 patients with clinical criteria of hereditary cancer (early onset, presence of multiple primary melanoma or 1 or more first- or second-degree relatives affected by secondary structural content prediction, a mutation scanning method that relies on the propensity for single-strand DNA to take on a three-dimensional structure that is highly sequence dependent, and sequencing the samples with alterations in the electrophoretic mobility. The prevalence of CDKN2A mutation in our study was 4.5% (1/22 and there was a correlation between family history and probability of mutation detection. We found the P48T mutation in 1 patient with 2 melanoma-affected relatives. The patient descends from Italian families and this mutation has been reported previously only in Italian families in two independent studies. This leads us to suggest the presence of a mutational "hotspot" within this gene or a founder mutation. We also detected a high prevalence (59.1% of polymorphisms, mainly alleles 500 C/G (7/31.8% or 540 C/T (6/27.3%, in the 3' untranslated region of exon 3. This result reinforces the idea that these rare polymorphic alleles have been significantly associated with the risk of developing melanoma.

  2. Radiosensitivity profiles from a panel of ovarian cancer cell lines exhibiting genetic alterations in p53 and disparate DNA-dependent protein kinase activities

    Energy Technology Data Exchange (ETDEWEB)

    Langland, Gregory T.; Yannone, Steven M.; Langland, Rachel A.; Nakao, Aki; Guan, Yinghui; Long, Sydney B.T.; Vonguyen, Lien; Chen, David J.; Gray, Joe W; Chen, Fanqing

    2009-09-07

    The variability of radiation responses in ovarian tumors and tumor-derived cell lines is poorly understood. Since both DNA repair capacity and p53 status can significantly alter radiation sensitivity, we evaluated these factors along with radiation sensitivity in a panel of sporadic human ovarian carcinoma cell lines. We observed a gradation of radiation sensitivity among these sixteen lines, with a five-fold difference in the LD50 between the most radiosensitive and the most radioresistant cells. The DNA-dependent protein kinase (DNA-PK) is essential for the repair of radiation induced DNA double-strand breaks in human somatic cells. Therefore, we measured gene copy number, expression levels, protein abundance, genomic copy and kinase activity for DNA-PK in all of our cell lines. While there were detectable differences in DNA-PK between the cell lines, there was no clear correlation with any of these differences and radiation sensitivity. In contrast, p53 function as determined by two independent methods, correlated well with radiation sensitivity, indicating p53 mutant ovarian cancer cells are typically radioresistant relative to p53 wild-type lines. These data suggest that the activity of regulatory molecules such as p53 may be better indicators of radiation sensitivity than DNA repair enzymes such as DNAPK in ovarian cancer.

  3. CDKN2A-mutation i en familie med arveligt malignt melanom

    DEFF Research Database (Denmark)

    Djursby, Malene; Wadt, Karin; Lorentzen, Henrik;

    2014-01-01

    Malignant melanoma (MM) is a frequent form of cancer with increasing incidence. 6-10% of patients with MM report a family history of MM, and in most populations 2% of unselected cases of MM carry a CDKN2A mutation. tvWe present a family with 24 cases of MM in nine persons from several generations......, caused by a previously undescribed germ-line intronic mutation in CDKN2A. Through genetic counselling and genetic testing high-risk persons in the family are located and offered regular screening for MM....

  4. Spontaneous multiple mutations show both proximal spacing consistent with chronocoordinate events and alterations with p53-deficiency.

    Science.gov (United States)

    Hill, Kathleen A; Wang, Jicheng; Farwell, Kelly D; Scaringe, William A; Sommer, Steve S

    2004-10-01

    Analysis of spontaneous multiple mutations in normal and tumor cells may constrain hypotheses about the mechanisms responsible for multiple mutations and provide insight into the mutator phenotype. In a previous study, spontaneous doublets in Big Blue mice were dramatically more frequent than expected by chance and exhibited a mutation pattern similar to that observed for single mutations [Mutat. Res. 452 (2000) 219]. The spacing between mutations in doublets was generally closer than expected by chance and the distribution of mutation spacing fit an exponential, albeit with substantial scatter. We now analyze 2658 additional mutants and confirm that doublets are enhanced dramatically relative to chance expectation. The spacing, frequency and pattern of spontaneous doublets and multiplets (domuplets) are examined as a function of age, tissue type, p53-deficiency and neoplasia in the new and combined data. The new and combined data confirm that the distribution of the spacing between mutations in doublets is non-random with the mutations more closely spaced than expected by chance (P germline, consistent with the generally reduced mutation frequency in the male germline (iii) doublet frequencies are elevated in somatic tissues of p53-deficient mice (Li-Fraumini cancer syndrome model; P = 0.005) and (iv) doublets and singlets in tumors from p53-deficient mice have a different mutation pattern (P = 0.007). The observations are consistent with chronocoordinate occurrence of spontaneous doublets and multiplets due to a transient error-prone condition and do not suggest a major role for the recently discovered Y family of error-prone polymerases. The enhancement of doublets in p53-deficient mice may contribute to cancer risk. PMID:15450421

  5. Over-expression of p53 mutants in LNCaP cells alters tumor growth and angiogenesis in vivo

    International Nuclear Information System (INIS)

    This study has investigated the impact of three specific dominant-negative p53 mutants (F134L, M237L, and R273H) on tumorigenesis by LNCaP prostate cancer cells. Mutant p53 proteins were associated with an increased subcutaneous 'take rate' in NOD-SCID mice, and increased production of PSA. Tumors expressing F134L and R273H grew slower than controls, and were associated with decreased necrosis and apoptosis, but not hypoxia. Interestingly, hypoxia levels were increased in tumors expressing M237L. There was less proliferation in F134L-bearing tumors compared to control, but this was not statistically significant. Angiogenesis was decreased in tumors expressing F134L and R273H compared with M237L, or controls. Conditioned medium from F134L tumors inhibited growth of normal human umbilical-vein endothelial cells but not telomerase-immortalized bone marrow endothelial cells. F134L tumor supernatants showed lower levels of VEGF and endostatin compared with supernatants from tumors expressing other mutants. Our results support the possibility that decreased angiogenesis might account for reduced growth rate of tumor cells expressing the F134L p53 mutation

  6. Dominant effects of Δ40p53 on p53 function and melanoma cell fate

    OpenAIRE

    Takahashi, Rie; Markovic, Svetomir; Scrable, Heidi

    2013-01-01

    The p53 gene encodes 12 distinct isoforms some of which can alter p53 activity in the absence of genomic alteration. Endogenous p53 isoforms have been identified in cancers; however, the function of these isoforms remains unclear. In melanoma, the frequency of p53 mutations is relatively low compared to other cancers suggesting that these isoforms may play a larger role in regulating p53 activity. We hypothesized that p53 function and therefore cell fate might be altered by the presence of Δ4...

  7. Mutant p53: Multiple Mechanisms Define Biologic Activity in Cancer

    OpenAIRE

    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 rev...

  8. CDKN2A and BAP1 germline mutations predispose to melanoma and mesothelioma.

    Science.gov (United States)

    Betti, M; Aspesi, A; Biasi, A; Casalone, E; Ferrante, D; Ogliara, P; Gironi, L C; Giorgione, R; Farinelli, P; Grosso, F; Libener, R; Rosato, S; Turchetti, D; Maffè, A; Casadio, C; Ascoli, V; Dianzani, C; Colombo, E; Piccolini, E; Pavesi, M; Miccoli, S; Mirabelli, D; Bracco, C; Righi, L; Boldorini, R; Papotti, M; Matullo, G; Magnani, C; Pasini, B; Dianzani, I

    2016-08-10

    BAP1 germline mutations predispose to a cancer predisposition syndrome that includes mesothelioma, cutaneous melanoma, uveal melanoma and other cancers. This co-occurrence suggests that these tumors share a common carcinogenic pathway. To evaluate this hypothesis, we studied 40 Italian families with mesothelioma and/or melanoma. The probands were sequenced for BAP1 and for the most common melanoma predisposition genes (i.e. CDKN2A, CDK4, TERT, MITF and POT1) to investigate if these genes may also confer susceptibility to mesothelioma. In two out of six families with both mesothelioma and melanoma we identified either a germline nonsense mutation (c.1153C > T, p.Arg385*) in BAP1 or a recurrent pathogenic germline mutation (c.301G > T, p.Gly101Trp) in CDKN2A. Our study suggests that CDKN2A, in addition to BAP1, could be involved in the melanoma and mesothelioma susceptibility, leading to the rare familial cancer syndromes. It also suggests that these tumors share key steps that drive carcinogenesis and that other genes may be involved in inherited predisposition to malignant mesothelioma and melanoma. PMID:27181379

  9. Mutant p53: multiple mechanisms define biologic activity in cancer

    Directory of Open Access Journals (Sweden)

    Michael Paul Kim

    2015-11-01

    Full Text Available 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 p53 alterations involve missense mutations that result in the production of mutant p53 proteins. Such mutant p53 proteins lack normal p53 function and may acquire novel functions, often with deleterious effects. Here, we review characterized mechanisms of mutant p53 gain of function in multiple 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 are reviewed and their limitations discussed.

  10. Thrombospondin-1 expression in urothelial carcinoma: prognostic significance and association with p53 alterations, tumour angiogenesis and extracellular matrix components

    Directory of Open Access Journals (Sweden)

    Michael MM

    2006-05-01

    Full Text Available Abstract Background Thrombospondin-1 (TSP-1 is an extracellular matrix component glycoprotein, which is known to be a potent inhibitor of angiogenesis and may be important in cancer invasiveness. We examined the TSP-1 expression in correlation with conventional clinicopathological parameters to clarify its prognostic significance in bladder cancer. In addition, the possible correlation of TSP-1 expression with microvessel count, VEGF expression, p53 expression as well as with the expression of the extracellular matrix components was studied to explore its implication in vascularization and tumour stroma remodeling. Methods The immunohistochemical expression of TSP-1 in tumour cells and in the tumour stroma was studied in 148 formalin-fixed paraffin-embedded urothelial cell carcinoma tissue samples. Results TSP-1 was detected in perivascular tissue, at the epithelial-stromal junction, in the stroma and in tumour cells in the majority of the cases. In tumour cells, low TSP-1 expression was observed in 43% of the cases, moderate and high in 7%, while 50% showed absence of TSP expression. A higher TSP-1 immunoreactivity in well and moderately differentiated tumours compared to poorly differentiated was noted. PT1 tumours showed decreased TSP-1 expression in comparison to pTa and pT2–4 tumours. Increased tumour cell TSP-1 expression was related to increased microvessel density. In the tumour stroma, 37% of the cases showed small amount of TSP-1 expression, 7.5% moderate and high, while 55% of the cases showed absence of TSP-1 stromal immunoreactivity. Stromal TSP-1 expression was inversely correlated with tumour stage and tumour size. This expression was also positively correlated with microvessel density, VEGF expression and extracellular matrix components tenascin and fibronectin. Using univariate and multivariate analysis we didn't find any significant correlation of TSP-1 expression in superficial tumours in both tumour cells and tumour stroma

  11. Thrombospondin-1 expression in urothelial carcinoma: prognostic significance and association with p53 alterations, tumour angiogenesis and extracellular matrix components

    International Nuclear Information System (INIS)

    Thrombospondin-1 (TSP-1) is an extracellular matrix component glycoprotein, which is known to be a potent inhibitor of angiogenesis and may be important in cancer invasiveness. We examined the TSP-1 expression in correlation with conventional clinicopathological parameters to clarify its prognostic significance in bladder cancer. In addition, the possible correlation of TSP-1 expression with microvessel count, VEGF expression, p53 expression as well as with the expression of the extracellular matrix components was studied to explore its implication in vascularization and tumour stroma remodeling. The immunohistochemical expression of TSP-1 in tumour cells and in the tumour stroma was studied in 148 formalin-fixed paraffin-embedded urothelial cell carcinoma tissue samples. TSP-1 was detected in perivascular tissue, at the epithelial-stromal junction, in the stroma and in tumour cells in the majority of the cases. In tumour cells, low TSP-1 expression was observed in 43% of the cases, moderate and high in 7%, while 50% showed absence of TSP expression. A higher TSP-1 immunoreactivity in well and moderately differentiated tumours compared to poorly differentiated was noted. PT1 tumours showed decreased TSP-1 expression in comparison to pTa and pT2–4 tumours. Increased tumour cell TSP-1 expression was related to increased microvessel density. In the tumour stroma, 37% of the cases showed small amount of TSP-1 expression, 7.5% moderate and high, while 55% of the cases showed absence of TSP-1 stromal immunoreactivity. Stromal TSP-1 expression was inversely correlated with tumour stage and tumour size. This expression was also positively correlated with microvessel density, VEGF expression and extracellular matrix components tenascin and fibronectin. Using univariate and multivariate analysis we didn't find any significant correlation of TSP-1 expression in superficial tumours in both tumour cells and tumour stroma in terns of the risk of recurrence and disease

  12. Alterations in p53-specific T cells and other lymphocyte subsets in breast cancer patients during vaccination with p53-peptide loaded dendritic cells and low-dose interleukin-2

    DEFF Research Database (Denmark)

    Svane, Inge Marie; Pedersen, Anders E; Nikolajsen, Kirsten;

    2008-01-01

    We have previously established a cancer vaccine using autologous DCs, generated by in vitro stimulation with IL-4 and GM-CSF, and pulsed with six HLA-A*0201 binding wild-type p53 derived peptides. This vaccine was used in combination with low-dose interleukin-2 in a recently published clinical...... Phase II trial where 26 HLA-A2+ patients with progressive late-stage metastatic breast cancer (BC) were included. Almost 1/3rd of the patients obtained stable disease or minor regression during treatment with a positive correlation to tumour over-expression of p53. In the present study, we performed a...... (CD44high, CCR-7low and CD62Llow). Furthermore, fresh blood from 18 cancer patients included in the vaccination trial were prospectively examined for more general treatment associated quantitative and qualitative changes in T cell subpopulations. We found that the frequency of CD4+ CD25high regulatory...

  13. Malignant transformation of neurofibromas in neurofibromatosis 1 is associated with CDKN2A/p16 inactivation

    DEFF Research Database (Denmark)

    Nielsen, G P; Stemmer-Rachamimov, A O; Ino, Y; Møller, Michael Boe; Rosenberg, A E; Louis, D N

    1999-01-01

    Patients with neurofibromatosis 1 (NF1) are predisposed to develop multiple neurofibromas (NFs) and are at risk for transformation of NFs to malignant peripheral nerve sheath tumors (MPNSTs). Little is known, however, about the biological events involved in the malignant transformation of NFs. We...... examined the CDKN2A/p16 gene and p16 protein in NFs and MPNSTs from patients with NF1. On immunohistochemical analysis, all NFs expressed p16 protein. The MPNSTs, however, were essentially immunonegative for p16, with striking transitions in cases that contained both benign and malignant elements. None of...... the benign tumors had CDKN2A/p16 deletions, whereas three of six MPNSTs appeared to have homozygous CDKN2A/p16 deletions. Methylation analysis and mutation analysis of CDKN2A/p16 in MPNSTs did not reveal any abnormalities. These results show that malignant transformation of NF is associated with loss...

  14. DNA Methylation in exon 1 of CDKN2A gene in formalin-fixed, paraffin-embedded colon cancer samples

    Directory of Open Access Journals (Sweden)

    Hossein Faramarzi

    2015-04-01

    Conclusion: The result of this study has been confirmed the role of CDKN2A gene promoter methylation of CpG sites of colorectal cancer as the leading cause of colorectal cancer. These data suggest that epigenetic silencing via aberrant methylation of the CDKN2A promoter plays a critical role in the inactivation of this tumor suppressor gene in colorectal cancer and can be used as a marker for early detection and identification of potential applications.

  15. DNA-mediated oxidation of p53.

    Science.gov (United States)

    Schaefer, Kathryn N; Barton, Jacqueline K

    2014-06-01

    Transcription factor p53 is the most commonly altered gene in human cancer. As a redox-active protein in direct contact with DNA, p53 can directly sense oxidative stress through DNA-mediated charge transport. Electron hole transport occurs over long distances through the π-stacked bases and leads to the oxidative dissociation of p53. The extent of protein dissociation depends upon the redox potential of the DNA in direct contact with each p53 monomer. The DNA sequence dependence of p53 oxidative dissociation was examined by electrophoretic mobility shift assays using oligonucleotides containing both synthetic and human p53 consensus sequences with an appended photooxidant, anthraquinone. Greater p53 dissociation is observed from sequences containing low-redox potential purine regions, particularly guanine triplets. Using denaturing polyacrylamide gel electrophoresis of irradiated anthraquinone-modified DNA, the DNA damage sites corresponding to sites of preferred electron hole localization were determined. The resulting DNA damage preferentially localizes to guanine doublets and triplets. Oxidative DNA damage is inhibited in the presence of p53, but only at sites in direct contact with p53. From these data, predictions about the sensitivity of human p53-binding sites to oxidative stress as well as possible biological implications have been made. On the basis of our data, the guanine pattern within the purine region of each p53-binding site determines the response of p53 to DNA oxidation, yielding for some sequences the oxidative dissociation of p53 from a distance and thereby providing another potential role for DNA charge transport chemistry within the cell. PMID:24853816

  16. Altered expression profile of glycolytic enzymes during testicular ischemia reperfusion injury is associated with the p53/TIGAR pathway: effect of fructose 1,6-diphosphate

    Science.gov (United States)

    Renno, Waleed M.

    2016-01-01

    Background. Testicular ischemia reperfusion injury (tIRI) is considered the mechanism underlying the pathology of testicular torsion and detorsion. Left untreated, tIRI can induce testis dysfunction, damage to spermatogenesis and possible infertility. In this study, we aimed to assess the activities and expression of glycolytic enzymes (GEs) in the testis and their possible modulation during tIRI. The effect of fructose 1,6-diphosphate (FDP), a glycolytic intermediate, on tIRI was also investigated. Methods. Male Sprague-Dawley rats were divided into three groups: sham, unilateral tIRI, and tIRI + FDP (2 mg/kg). tIRI was induced by occlusion of the testicular artery for 1 h followed by 4 h of reperfusion. FDP was injected peritoneally 30 min prior to reperfusion. Histological and biochemical analyses were used to assess damage to spermatogenesis, activities of major GEs, and energy and oxidative stress markers. The relative mRNA expression of GEs was evaluated by real-time PCR. ELISA and immunohistochemistry were used to evaluate the expression of p53 and TP53-induced glycolysis and apoptosis regulator (TIGAR). Results. Histological analysis revealed tIRI-induced spermatogenic damage as represented by a significant decrease in the Johnsen biopsy score. In addition, tIRI reduced the activities of hexokinase 1, phosphofructokinase-1, glyceraldehyde 3-phosphate dehydrogenase, and lactate dehydrogenase C. However, mRNA expression downregulation was detected only for hexokinase 1, phosphoglycerate kinase 2, and lactate dehydrogenase C. ATP and NADPH depletion was also induced by tIRI and was accompanied by an increased Malondialdehyde concentration, reduced glutathione level, and reduced superoxide dismutase and catalase enzyme activities. The immunoexpression of p53 and TIGAR was markedly increased after tIRI. The above tIRI-induced alterations were attenuated by FDP treatment. Discussion. Our findings indicate that tIRI-induced spermatogenic damage is associated with

  17. Microbial Regulation of p53 Tumor Suppressor.

    Science.gov (United States)

    Zaika, Alexander I; Wei, Jinxiong; Noto, Jennifer M; Peek, Richard M

    2015-09-01

    p53 tumor suppressor has been identified as a protein interacting with the large T antigen produced by simian vacuolating virus 40 (SV40). Subsequent research on p53 inhibition by SV40 and other tumor viruses has not only helped to gain a better understanding of viral biology, but also shaped our knowledge of human tumorigenesis. Recent studies have found, however, that inhibition of p53 is not strictly in the realm of viruses. Some bacterial pathogens also actively inhibit p53 protein and induce its degradation, resulting in alteration of cellular stress responses. This phenomenon was initially characterized in gastric epithelial cells infected with Helicobacter pylori, a bacterial pathogen that commonly infects the human stomach and is strongly linked to gastric cancer. Besides H. pylori, a number of other bacterial species were recently discovered to inhibit p53. These findings provide novel insights into host-bacteria interactions and tumorigenesis associated with bacterial infections. PMID:26379246

  18. Microbial Regulation of p53 Tumor Suppressor.

    Directory of Open Access Journals (Sweden)

    Alexander I Zaika

    2015-09-01

    Full Text Available p53 tumor suppressor has been identified as a protein interacting with the large T antigen produced by simian vacuolating virus 40 (SV40. Subsequent research on p53 inhibition by SV40 and other tumor viruses has not only helped to gain a better understanding of viral biology, but also shaped our knowledge of human tumorigenesis. Recent studies have found, however, that inhibition of p53 is not strictly in the realm of viruses. Some bacterial pathogens also actively inhibit p53 protein and induce its degradation, resulting in alteration of cellular stress responses. This phenomenon was initially characterized in gastric epithelial cells infected with Helicobacter pylori, a bacterial pathogen that commonly infects the human stomach and is strongly linked to gastric cancer. Besides H. pylori, a number of other bacterial species were recently discovered to inhibit p53. These findings provide novel insights into host-bacteria interactions and tumorigenesis associated with bacterial infections.

  19. Promoter methylation of CDKN2A and lack of p16 expression characterize patients with hepatocellular carcinoma

    International Nuclear Information System (INIS)

    The product of CDKN2A, p16 is an essential regulator of the cell cycle controlling the entry into the S-phase. Herein, we evaluated CDKN2A promoter methylation and p16 protein expression for the differentiation of hepatocellular carcinoma (HCC) from other liver tumors. Tumor and corresponding non-tumor liver tissue samples were obtained from 85 patients with liver tumors. CDKN2A promoter methylation was studied using MethyLight technique and methylation-specific PCR (MSP). In the MethyLight analysis, samples with ≥ 4% of PMR (percentage of methylated reference) were regarded as hypermethylated. p16 expression was evaluated by immunohistochemistry in tissue sections (n = 148) obtained from 81 patients using an immunoreactivity score (IRS) ranging from 0 (no expression) to 6 (strong expression). Hypermethylation of the CDKN2A promoter was found in 23 HCCs (69.7%; mean PMR = 42.34 ± 27.8%), six (20.7%; mean PMR = 31.85 ± 18%) liver metastases and in the extralesional tissue of only one patient. Using MSP, 32% of the non-tumor (n = 85), 70% of the HCCs, 40% of the CCCs and 24% of the liver metastases were hypermethylated. Correspondingly, nuclear p16 expression was found immunohistochemically in five (10.9%, mean IRS = 0.5) HCCs, 23 (92%; mean IRS = 4.9) metastases and only occasionally in hepatocytes of non-lesional liver tissues (mean IRS = 1.2). The difference of CDKN2A-methylation and p16 protein expression between HCCs and liver metastases was statistically significant (p < 0.01, respectively). Promoter methylation of CDKN2A gene and lack of p16 expression characterize patients with HCC

  20. Mutation analysis of genes that control the G1/S cell cycle in melanoma: TP53, CDKN1A, CDKN2A, and CDKN2B

    International Nuclear Information System (INIS)

    The role of genes involved in the control of progression from the G1 to the S phase of the cell cycle in melanoma tumors in not fully known. The aim of our study was to analyse mutations in TP53, CDKN1A, CDKN2A, and CDKN2B genes in melanoma tumors and melanoma cell lines We analysed 39 primary and metastatic melanomas and 9 melanoma cell lines by single-stranded conformational polymorphism (SSCP). The single-stranded technique showed heterozygous defects in the TP53 gene in 8 of 39 (20.5%) melanoma tumors: three new single point mutations in intronic sequences (introns 1 and 2) and exon 10, and three new single nucleotide polymorphisms located in introns 1 and 2 (C to T transition at position 11701 in intron 1; C insertion at position 11818 in intron 2; and C insertion at position 11875 in intron 2). One melanoma tumor exhibited two heterozygous alterations in the CDKN2A exon 1 one of which was novel (stop codon, and missense mutation). No defects were found in the remaining genes. These results suggest that these genes are involved in melanoma tumorigenesis, although they may be not the major targets. Other suppressor genes that may be informative of the mechanism of tumorigenesis in skin melanomas should be studied

  1. Risk of Non-Melanoma Cancers in First-Degree Relatives of CDKN2A Mutation Carriers

    OpenAIRE

    Mukherjee, Bhramar; DeLancey, John Oliver; Raskin, Leon; Everett, Jessica; Jeter, Joanne; Begg, Colin B; Orlow, Irene; Berwick, Marianne; Armstrong, Bruce K.; Kricker, Anne; Marrett, Loraine D; Millikan, Robert C.; Culver, Hoda Anton; Rosso, Stefano; Zanetti, Roberto

    2012-01-01

    The purpose of this study was to quantify the risk of cancers other than melanoma among family members of CDKN2A mutation carriers using data from the Genes, Environment and Melanoma study. Relative risks (RRs) of all non-melanoma cancers among first-degree relatives (FDRs) of melanoma patients with CDKN2A mutations (n = 65) and FDRs of melanoma patients without mutations (n = 3537) were calculated as the ratio of estimated event rates (number of cancers/total person-years) in FDRs of carrier...

  2. Correlation of p53 gene mutation and expression of P53 protein in cholangiocarcinoma

    Institute of Scientific and Technical Information of China (English)

    Xiao-Fang Liu; Hao Zhang; Shi-Guang Zhu; Xian-Ting Zhou; Hai-Long Su; Zheng Xu; Shao-Jun Li

    2006-01-01

    AIM: To characterize the tumor suppressor gene p53 mutations and study the correlation of p53 gene mutation and the expression of P53 protein in cholangiocarcinoma.METHODS: A total of 36 unselected, frozen samples of cholangiocarcinoma were collected. p53 gene status(exon 5-8) and P53 protein were examined by automated sequencing and immunohistochemical staining, combined with the clinical parameters of patients.RESULTS: p53 gene mutations were found in 22 of 36 (61.1%) patients. Nineteen of 36 (52.8%) patients were positive for P53 protein expression. There were significant differences in extent of differentiation and invasion between the positive and negative expression of P53 protein. However, there were no significant differences in pathologic parameters between the mutations and non-mutations.CONCLUSION: The alterations of the p53 gene evaluated by DNA sequence analysis is relatively accurate. Expression of P53 protein could not act as an independent index to estimate the prognosis of cholangiocarcinoma.

  3. OTUD5 regulates p53 stability by deubiquitinating p53.

    Directory of Open Access Journals (Sweden)

    Judong Luo

    Full Text Available BACKGROUND: The p53 tumour suppressor protein is a transcription factor that prevents oncogenic progression by activating the expression of apoptosis and cell-cycle arrest genes in stressed cells. The stability of p53 is tightly regulated by ubiquitin-dependent degradation, driven mainly by its negative regulators ubiquitin ligase MDM2. PRINCIPAL FINDINGS: In this study, we have identified OTUD5 as a DUB that interacts with and deubiquitinates p53. OTUD5 forms a direct complex with p53 and controls level of ubiquitination. The function of OTUD5 is required to allow the rapid activation of p53-dependent transcription and a p53-dependent apoptosis in response to DNA damage stress. CONCLUSIONS: As a novel deubiquitinating enzyme for p53, OTUD5 is required for the stabilization and the activation of a p53 response.

  4. Inherited coding variants at the CDKN2A locus influence susceptibility to acute lymphoblastic leukaemia in children

    DEFF Research Database (Denmark)

    Xu, Heng; Zhang, Hui; Yang, Wenjian;

    2015-01-01

    of haematopoietic progenitor cells, and is preferentially retained in ALL tumour cells. Resequencing the CDKN2A-CDKN2B locus in 2,407 childhood ALL cases reveals 19 additional putative functional germline variants. These results provide direct functional evidence for the influence of inherited...

  5. A neurogenic tumor containing a low-grade malignant peripheral nerve sheath tumor (MPNST) component with loss of p16 expression and homozygous deletion of CDKN2A/p16: a case report showing progression from a neurofibroma to a high-grade MPNST.

    Science.gov (United States)

    Tajima, Shogo; Koda, Kenji

    2015-01-01

    Development of malignant peripheral nerve sheath tumors (MPNSTs) is a stepwise process that involves the alteration of many cell cycle regulators and the double inactivation of the NF1 gene. Inactivation of the TP53 gene and deletion of the CDKN2A/p16 gene are known to play an important role in the process. Herein, we present a 19-year-old man with a familial history of neurofibromatosis type 1, in whom the tumor arose from the intercostal nerve and showed 3 components: a neurofibroma, a low-grade MPNST, and a high-grade MPNST. Loss of p16 expression and homozygous deletion of the CDKN2A/p16 gene were observed in both the low-grade and the high-grade MPNST. In contrast to low-grade MPNSTs, high-grade MPNSTs generally tend to lose expression of p16 and harbor homozygous deletion of the CDKN2A/p16 gene. Loss of p16 expression and homozygous deletion of the CDKN2A/p16 gene in low-grade MPNST in our case might be related to its progression to high-grade MPNST. To the best of our knowledge, this is the first study correlating the p16 expression status and CDKN2A/p16 gene alteration in low-grade MPNSTs. PMID:26191206

  6. P53 MUTATIONS IN HUMAN LUNG-TUMORS

    NARCIS (Netherlands)

    MILLER, CW; ASLO, A; KOK, K; YOKOTA, J; BUYS, CHCM; TERADA, M; KOEFFLER, HP; Simon, K.

    1992-01-01

    Mutation of one p53 allele and loss of the normal p53 allele [loss of heterozygosity (LOH)] occur in many tumors including lung cancers. These alterations apparently contribute to development of cancer by interfering with the tumor suppressor activity of p53. We directly sequenced amplified DNA in t

  7. Targeting Oncogenic Mutant p53 for Cancer Therapy

    OpenAIRE

    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 ...

  8. Hormonal control of p53 and chemoprevention

    International Nuclear Information System (INIS)

    Improvements in the detection and treatment of breast cancer have dramatically altered its clinical course and outcome. However, prevention of breast cancer remains an elusive goal. Parity, age of menarche, and age at menopause are major risk factors drawing attention to the important role of the endocrine system in determining the risk of breast cancer, while heritable breast cancer susceptibility syndromes have implicated tumor suppressor genes as important targets. Recent work demonstrating hormonal modulation of the p53 tumor suppressor pathway draws together these established determinants of risk to provide a model of developmental susceptibility to breast cancer. In this model, the mammary epithelium is rendered susceptible due to impaired p53 activity during specific periods of mammary gland development, but specific endocrine stimuli serve to activate p53 function and to mitigate this risk. The results focus attention on p53 as a molecular target for therapies to reduce the risk of breast cancer

  9. Tumor suppressor p53 response is blunted

    International Nuclear Information System (INIS)

    the p53 pathway. These findings suggest that chronic irradiation at low dose rate alters the p53-dependent signal transduction pathway. Wearing away the p53 pathway by chronic irradiation my have important implication for radiation protection. Biological meaning of these phenomenon will be studied in molecular aspects. These results were reported in Radiation Research (151: 368-372, 1999). (author)

  10. p53 mutations increase resistance to ionizing radiation

    International Nuclear Information System (INIS)

    Mouse and human tumors of diverse origin frequently have somatically acquired mutations or rearrangements of the p53 gene, or they have lost one or both copies of the gene. Although wild-type p53 protein is believed to function as a tumor-suppressor gene, it is as yet unclear how p53 mutations lead to neoplastic development. Wild-type p53 has been postulated to play a role in DNA repair, suggesting that expression of mutant forms of p53 might alter cellular resistance to the DNA damage caused by γ radiation. Moreover, p53 is thought to function as a cell cycle checkpoint after irradiation, also suggesting that mutant p53 might change the cellular proliferative response to radiation. The authors have used transgenic mice expressing one of two mutant alleles of p53 to test this prediction. Their results show that expression of both mutant variants of the mouse p53 gene significantly increases the cellular resistance of a variety of hematopoietic cell lineages to γ radiation. These observations provide direct evidence that p53 mutations affect the cellular response to DNA damage, either by increasing DNA repair processes or, possibly, by increasing cellular tolerance to DNA damage. The association of p53 mutations with increased radioresistance suggests possible mechanisms through which alterations in the p53 gene might lead to oncogenic transformation. 53 refs., 5 figs

  11. Exposure to depleted uranium does not alter the co-expression of HER-2/neu and p53 in breast cancer patients

    Directory of Open Access Journals (Sweden)

    Al-Toriahi Kaswer M

    2011-03-01

    Full Text Available Abstract Background Amongst the extensive literature on immunohistochemical profile of breast cancer, very little is found on populations exposed to a potential risk factor such as depleted uranium. This study looked at the immunohistochemical expression of HER-2/neu (c-erbB2 and p53 in different histological types of breast cancer found in the middle Euphrates region of Iraq, where the population has been exposed to high levels of depleted uranium. Findings The present investigation was performed over a period starting from September 2008 to April 2009. Formalin-fixed, paraffin-embedded blocks from 70 patients with breast cancer (62 ductal and 8 lobular carcinoma were included in this study. A group of 25 patients with fibroadenoma was included as a comparative group, and 20 samples of normal breast tissue sections were used as controls. Labeled streptavidin-biotin (LSAB+ complex method was employed for immunohistochemical detection of HER-2/neu and p53. The detection rate of HER-2/neu and p53 immunohistochemical expression were 47.14% and 35.71% respectively in malignant tumors; expression was negative in the comparative and control groups (p HER-2/neu immunostaining was significantly associated with histological type, tumor size, nodal involvement, and recurrence of breast carcinoma (p p Both biomarkers were positively correlated with each other. Furthermore, all the cases that co-expressed both HER-2/neu and p53 showed the most unfavorable biopathological profile. Conclusion P53 and HER-2/neu over-expression play an important role in pathogenesis of breast carcinoma. The findings indicate that in regions exposed to high levels of depleted uranium, although p53 and HER-2/neu overexpression are both high, correlation of their expression with age, grade, tumor size, recurrence and lymph node involvement is similar to studies that have been conducted on populations not exposed to depleted uranium. HER-2/neu expression in breast cancer was higher

  12. Mitochondrial DNA alterations correlate with the pathological status and the immunological ER, PR, HER-2/neu, p53 and Ki-67 expression in breast invasive ductal carcinoma.

    Science.gov (United States)

    Lin, Chen-Sung; Chang, Shi-Chuan; Ou, Liang-Hung; Chen, Chien-Ming; Hsieh, Sophie Swen-Wan; Chung, Yu-Ping; King, Kuang-Liang; Lin, Shoei-Loong; Wei, Yau-Huei

    2015-06-01

    We analyzed the changes in mitochondrial DNA (mtDNA) copy numbers and the shifting of mtDNA D310 sequence variations (D310 mutation) with their relationships to pathological status and the expression levels of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER-2/neu), tumor-suppressor protein p53 and cellular proliferation protein Ki-67 in breast invasive ductal carcinoma (BIDC), respectively. Fifty-one paraffin-embedded BIDCs and their paired non-cancerous breast tissues were dissected for DNA extraction. The mtDNA copy number and mtDNA D310 sequence variations were determined by quantitative real-time polymerase chain reaction (q-PCR) and PCR-based direct sequencing, respectively. The expression levels of ER, PR, HER-2/neu, p53 and Ki-67 were determined by immunohistochemical (IHC) staining. Compared to the paired non-cancerous breast tissues, 24 (47.1%) BIDCs had elevated mtDNA copy numbers and 29 (56.9%) harbored mtDNA D310 mutations. Advanced T-status (p=0.056), negative-ER (p=0.005), negative-PR (p=0.007), positive-p53 (p=0.050) and higher Ki-67 (p=0.004) expressions were related to a higher mtDNA copy ratio. In addition, advanced T-status (p=0.019) and negative-HER-2/neu expression (p=0.061) were associated with mtDNA D310 mutations. In conclusion, higher mtDNA copy ratio and D310 mutations may be relevant biomarkers correlated with pathological T-status and the expression levels of ER, PR, HER-2/neu, p53 and Ki-67 in BIDCs. PMID:25845386

  13. Exposure to depleted uranium does not alter the co-expression of HER-2/neu and p53 in breast cancer patients

    OpenAIRE

    Al-Toriahi Kaswer M; Jumaa Alaa S; Al-Janabi Asad A; Al-Mumen Mais M; Yasseen Akeel A

    2011-01-01

    Abstract Background Amongst the extensive literature on immunohistochemical profile of breast cancer, very little is found on populations exposed to a potential risk factor such as depleted uranium. This study looked at the immunohistochemical expression of HER-2/neu (c-erbB2) and p53 in different histological types of breast cancer found in the middle Euphrates region of Iraq, where the population has been exposed to high levels of depleted uranium. Findings The present investigation was per...

  14. DNA Methylation in exon 1 of CDKN2A gene in formalin-fixed, paraffin-embedded colon cancer samples

    OpenAIRE

    Hossein Faramarzi; Elham Moslemi; Amir Izadi

    2015-01-01

    Background: The molecular studies indicate some of the genes in the promoter region itself, will undergo methylation. Methylation of CpG islands in the promoter region of that cause silence or reduced expression of genes involved in cell growth pathways, which are colorectal cancer causing agents. Detection of methylation status can be used as a marker for cancer diagnosis and prediction of disease. CDKN2A tumor suppressor gene encodes a protein, which inhibit CDK 4/6 and loss of retinoblasto...

  15. Genome-wide analyses implicate 33 loci in heritable dog osteosarcoma, including regulatory variants near CDKN2A/B

    OpenAIRE

    Karlsson, Elinor K.; Sigurdsson, Snaevar; Ivansson, Emma; Thomas, Rachael; Elvers, Ingegerd; Wright, Jason; Howald, Cedric; Tonomura, Noriko; Perloski, Michele; Swofford, Ross; Biagi, Tara; Fryc, Sarah; Anderson, Nathan; Courtay-Cahen, Celine; Youell, Lisa

    2013-01-01

    Background: Canine osteosarcoma is clinically nearly identical to the human disease, but is common and highly heritable, making genetic dissection feasible. Results: Through genome-wide association analyses in three breeds (greyhounds, Rottweilers, and Irish wolfhounds), we identify 33 inherited risk loci explaining 55% to 85% of phenotype variance in each breed. The greyhound locus exhibiting the strongest association, located 150 kilobases upstream of the genes CDKN2A/B, is also the most re...

  16. Genome-wide analyses implicate 33 loci in heritable dog osteosarcoma, including regulatory variants near CDKN2A/B

    OpenAIRE

    Karlsson, Elinor K.; Sigurdsson, Snaevar; Ivansson, Emma; Thomas, Rachael; Elvers, Ingegerd; Wright, Jason; Howald, Cedric; Tonomura, Noriko; Perloski, Michele; Swofford, Ross; Biagi, Tara; Fryc, Sarah; Anderson, Nathan; Courtay-Cahen, Celine; Youell, Lisa

    2013-01-01

    BACKGROUND: Canine osteosarcoma is clinically nearly identical to the human disease, but is common and highly heritable, making genetic dissection feasible. RESULTS: Through genome-wide association analyses in three breeds (greyhounds, Rottweilers, and Irish wolfhounds), we identify 33 inherited risk loci explaining 55% to 85% of phenotype variance in each breed. The greyhound locus exhibiting the strongest association, located 150 kilobases upstream of the genes CDKN2A/B, is also the most re...

  17. Genome-wide analyses implicate 33 loci in heritable dog osteosarcoma, including regulatory variants near CDKN2A/B

    OpenAIRE

    Karlsson, Elinor K.; Sigurdsson, Snaevar; Ivansson, Emma; Thomas, Rachael; Elvers, Ingegerd; Wright, Jason; Howald, Cedric; Tonomura, Noriko; Perloski, Michele; Swofford, Ross; Biagi, Tara; Fryc, Sarah; Anderson, Nathan; Courtay-Cahen, Celine; Youell, Lisa

    2013-01-01

    Background: Canine osteosarcoma is clinically nearly identical to the human disease, but is common and highly heritable, making genetic dissection feasible. Results: Through genome-wide association analyses in three breeds (greyhounds, Rottweilers, and Irish wolfhounds), we identify 33 inherited risk loci explaining 55% to 85% of phenotype variance in each breed. The greyhound locus exhibiting the strongest association, located 150 kilobases upstream of the genes CDKN2A/B, is also th...

  18. P53 Mdm2 Inhibitors

    NARCIS (Netherlands)

    Khoury, Kareem; Doemling, Alex

    2012-01-01

    The protein-protein interaction (PPI) between p53 and its negative regulator MDM2 comprises one of the most important and intensely studied PPI's involved in preventing the initiation of cancer. The interaction between p53 and MDM2 is conformation-based and is tightly regulated on multiple levels. D

  19. JC Virus T-Antigen in Colorectal Cancer Is Associated with p53 Expression and Chromosomal Instability, Independent of CpG Island Methylator Phenotype

    Directory of Open Access Journals (Sweden)

    Katsuhiko Nosho

    2009-01-01

    Full Text Available JC virus has a transforming gene encoding JC virus T-antigen (JCVT. JCVT may inactivate wild-type p53, cause chromosomal instability (CIN, and stabilize β-catenin. A link between JCVT and CpG island methylator phenotype (CIMP has been suggested. However, no large-scale study has examined the relations of JCVT with molecular alterations, clinical outcome, or prognosis in colon cancer. We detected JCVT expression (by immunohistochemistry in 271 (35% of 766 colorectal cancers. We quantified DNA methylation in eight CIMP-specific promoters (CACNA1G, CDKN2A, CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1 and eight other loci (CHFR, HIC1, IGFBP3, MGMT, MINT1, MINT31, p14, WRN by MethyLight. We examined loss of heterozygosity in 2p, 5q, 17q, and 18q. JCVT was significantly associated with p53 expression (P < .0001, p21 loss (P < .0001, CIN (≥2 chromosomal segments with LOH; P < .0001, nuclear β-catenin (P = .006, LINE-1 hypomethylation (P = .002, and inversely with CIMP-high (P = .0005 and microsatellite instability (MSI (P < .0001, but not with PIK3CA mutation. In multivariate logistic regression analysis, the associations of JCVT with p53 [adjusted odds ratio (OR, 8.45; P < .0001], CIN (adjusted OR, 2.53; P = .003, cyclin D1 (adjusted OR, 1.57; P = .02, LINE-1 hypomethylation (adjusted OR, 1.97 for a 30% decline as a unit; P = .03, BRAF mutation (adjusted OR, 2.20; P = .04, and family history of colorectal cancer (adjusted OR, 0.64; P = .04 remained statistically significant. However, JCVT was no longer significantly associated with CIMP, MSI, β-catenin, or cyclooxygenase-2 expression in multivariate analysis. JCVT was unrelated with patient survival. In conclusion, JCVT expression in colorectal cancer is independently associated with p53 expression and CIN, which may lead to uncontrolled cell proliferation.

  20. p53 in stem cells

    Institute of Scientific and Technical Information of China (English)

    Valeriya; Solozobova; Christine; Blattner

    2011-01-01

    p53 is well known as a "guardian of the genome" for differentiated cells,in which it induces cell cycle arrest and cell death after DNA damage and thus contributes to the maintenance of genomic stability.In addition to this tumor suppressor function for differentiated cells,p53 also plays an important role in stem cells.In this cell type,p53 not only ensures genomic integrity after genotoxic insults but also controls their proliferation and differentiation.Additionally,p53 provides an effective barrier for the generation of pluripotent stem celllike cells from terminally differentiated cells.In this review,we summarize our current knowledge about p53 activities in embryonic,adult and induced pluripotent stem cells.

  1. Targeting oncogenic mutant p53 for cancer therapy

    OpenAIRE

    Tomoo eIwakuma; Alejandro eParrales

    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 (GOF) activities and exacerbate malignant properties of cancer cells, such as metastasis and drug resistance. Increasing evidence reveals that stabilization of mutant p...

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

    OpenAIRE

    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 expressi...

  3. Small-Molecule Inhibitors of the MDM2-p53 Protein-Protein Interaction to Reactivate p53 Function: A Novel Approach for Cancer Therapy

    OpenAIRE

    Shangary, Sanjeev; Wang, Shaomeng

    2009-01-01

    Tumor suppressor p53 is an attractive cancer therapeutic target because it can be functionally activated to eradicate tumors. Direct gene alterations in p53 or interaction between p53 and MDM2 proteins are two alternative mechanisms for the inactivation of p53 function. Designing small molecules to block the MDM2-p53 interaction and reactivate the p53 function is a promising therapeutic strategy for the treatment of cancers retaining wild-type p53. This review will highlight recent advances i...

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

    OpenAIRE

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

    2014-01-01

    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 tra...

  5. Promoter methylation status of hMLH1,MGMT,and CDKN2A/p16 in colorectal adenomas

    Institute of Scientific and Technical Information of China (English)

    Vasiliki; Psofaki; Chryssoula; Kalogera; Nikolaos; Tzambouras; Dimitrios; Stephanou; Epameinondas; Tsianos; Konstantin; Seferiadis; Georgios; Kolios

    2010-01-01

    AIM:To investigate aberrant DNA methylation of CpG islands and subsequent low-or high-level DNA microsatellite instability(MSI)which is assumed to drive colon carcinogenesis. METHODS:DNA of healthy individuals,adenoma(tu-bular or villous/tubulovillous)patients,and colorectal carcinoma patients who underwent colonoscopy was used for assessing the prevalence of aberrant DNA methylation of human DNA mismatch repair gene mutator L homologue 1(hMLH1),Cyclin-dependent kinase inhibitor 2A(CDKN2A/p16),and O-6-methy...

  6. Necdin, a p53-target gene, is an inhibitor of p53-mediated growth arrest.

    Directory of Open Access Journals (Sweden)

    Julie Lafontaine

    Full Text Available In vitro, cellular immortalization and transformation define a model for multistep carcinogenesis and current ongoing challenges include the identification of specific molecular events associated with steps along this oncogenic pathway. Here, using NIH3T3 cells, we identified transcriptionally related events associated with the expression of Polyomavirus Large-T antigen (PyLT, a potent viral oncogene. We propose that a subset of these alterations in gene expression may be related to the early events that contribute to carcinogenesis. The proposed tumor suppressor Necdin, known to be regulated by p53, was within a group of genes that was consistently upregulated in the presence of PyLT. While Necdin is induced following p53 activation with different genotoxic stresses, Necdin induction by PyLT did not involve p53 activation or the Rb-binding site of PyLT. Necdin depletion by shRNA conferred a proliferative advantage to NIH3T3 and PyLT-expressing NIH3T3 (NIHLT cells. In contrast, our results demonstrate that although overexpression of Necdin induced a growth arrest in NIH3T3 and NIHLT cells, a growing population rapidly emerged from these arrested cells. This population no longer showed significant proliferation defects despite high Necdin expression. Moreover, we established that Necdin is a negative regulator of p53-mediated growth arrest induced by nutlin-3, suggesting that Necdin upregulation could contribute to the bypass of a p53-response in p53 wild type tumors. To support this, we characterized Necdin expression in low malignant potential ovarian cancer (LMP where p53 mutations rarely occur. Elevated levels of Necdin expression were observed in LMP when compared to aggressive serous ovarian cancers. We propose that in some contexts, the constitutive expression of Necdin could contribute to cancer promotion by delaying appropriate p53 responses and potentially promote genomic instability.

  7. Immunohistochemical Determination of p53 Protein Overexpression for Predicting p53 Gene Mutations in Hepatocellular Carcinoma: A Meta-Analysis

    Science.gov (United States)

    Deng, Miao; Liu, Dechun; Ma, Qingyong; Feng, Xiaoshan

    2016-01-01

    Background Whether increased expression of the tumor suppressor protein p53 indicates a p53 gene mutation in hepatocellular carcinoma (HCC) remains unclear. We conducted a meta-analysis to determine whether p53 protein overexpression detected by immunohistochemistry (IHC) offers a diagnostic prediction for p53 gene mutations in HCC patients. Methods Systematic literature searches were conducted with an end date of December 2015. A meta-analysis was performed to estimate the diagnostic accuracy of IHC-determined p53 protein overexpression in the prediction of p53 gene mutations in HCC. Sensitivity, subgroup, and publication bias analyses were also conducted. Results Thirty-six studies were included in the meta-analysis. The results showed that the overall sensitivity and specificity for IHC-determined p53 overexpression in the diagnostic prediction of p53 mutations in HCC were 0.83 (95% CI: 0.80–0.86) and 0.74 (95% CI: 0.71–0.76), respectively. The summary positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 2.65 (95% CI: 2.21–3.18) and 0.36 (95% CI: 0.26–0.50), respectively. The diagnostic odds ratio (DOR) of IHC-determined p53 overexpression in predicting p53 mutations ranged from 0.56 to 105.00 (pooled, 9.77; 95% CI: 6.35–15.02), with significant heterogeneity between the included studies (I2 = 40.7%, P = 0.0067). Moreover, subgroup and sensitivity analyses did not alter the results of the meta-analysis. However, potential publication bias was present in the current meta-analysis. Conclusion The upregulation of the tumor suppressor protein p53 was indeed linked to p53 gene mutations. IHC determination of p53 overexpression can predict p53 gene mutations in HCC patients. PMID:27428001

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

    Science.gov (United States)

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

  9. Stability of p53 homologs.

    Directory of Open Access Journals (Sweden)

    Tobias Brandt

    Full Text Available Most proteins have not evolved for maximal thermal stability. Some are only marginally stable, as for example, the DNA-binding domains of p53 and its homologs, whose kinetic and thermodynamic stabilities are strongly correlated. Here, we applied high-throughput methods using a real-time PCR thermocycler to study the stability of several full-length orthologs and paralogs of the p53 family of transcription factors, which have diverse functions, ranging from tumour suppression to control of developmental processes. From isothermal denaturation fluorimetry and differential scanning fluorimetry, we found that full-length proteins showed the same correlation between kinetic and thermodynamic stability as their isolated DNA-binding domains. The stabilities of the full-length p53 orthologs were marginal and correlated with the temperature of their organism, paralleling the stability of the isolated DNA-binding domains. Additionally, the paralogs p63 and p73 were significantly more stable and long-lived than p53. The short half-life of p53 orthologs and the greater persistence of the paralogs may be biologically relevant.

  10. Influenza A Viruses Control Expression of Proviral Human p53 Isoforms p53β and Δ133p53α

    OpenAIRE

    Terrier, Olivier; Marcel, Virginie; Cartet, Gaëlle; Lane, David P; Lina, Bruno; Rosa-Calatrava, Manuel; Bourdon, Jean-Christophe

    2012-01-01

    Previous studies have described the role of p53 isoforms, including p53β and Δ133p53α, in the modulation of the activity of full-length p53, which regulates cell fate. In the context of influenza virus infection, an interplay between influenza viruses and p53 has been described, with p53 being involved in the antiviral response. However, the role of physiological p53 isoforms has never been explored in this context. Here, we demonstrate that p53 isoforms play a role in influenza A virus infec...

  11. Human surfactant protein D alters oxidative stress and HMGA1 expression to induce p53 apoptotic pathway in eosinophil leukemic cell line.

    Directory of Open Access Journals (Sweden)

    Lakshna Mahajan

    Full Text Available Surfactant protein D (SP-D, an innate immune molecule, has an indispensable role in host defense and regulation of inflammation. Immune related functions regulated by SP-D include agglutination of pathogens, phagocytosis, oxidative burst, antigen presentation, T lymphocyte proliferation, cytokine secretion, induction of apoptosis and clearance of apoptotic cells. The present study unravels a novel ability of SP-D to reduce the viability of leukemic cells (eosinophilic leukemic cell line, AML14.3D10; acute myeloid leukemia cell line, THP-1; acute lymphoid leukemia cell lines, Jurkat, Raji; and human breast epithelial cell line, MCF-7, and explains the underlying mechanisms. SP-D and a recombinant fragment of human SP-D (rhSP-D induced G2/M phase cell cycle arrest, and dose and time-dependent apoptosis in the AML14.3D10 eosinophilic leukemia cell line. Levels of various apoptotic markers viz. activated p53, cleaved caspase-9 and PARP, along with G2/M checkpoints (p21 and Tyr15 phosphorylation of cdc2 showed significant increase in these cells. We further attempted to elucidate the underlying mechanisms of rhSP-D induced apoptosis using proteomic analysis. This approach identified large scale molecular changes initiated by SP-D in a human cell for the first time. Among others, the proteomics analysis highlighted a decreased expression of survival related proteins such as HMGA1, overexpression of proteins to protect the cells from oxidative burst, while a drastic decrease in mitochondrial antioxidant defense system. rhSP-D mediated enhanced oxidative burst in AML14.3D10 cells was confirmed, while antioxidant, N-acetyl-L-cysteine, abrogated the rhSP-D induced apoptosis. The rhSP-D mediated reduced viability was specific to the cancer cell lines and viability of human PBMCs from healthy controls was not affected. The study suggests involvement of SP-D in host's immunosurveillance and therapeutic potential of rhSP-D in the eosinophilic leukemia and

  12. Knockdown of Merm1/Wbscr22 attenuates sensitivity of H460 non-small cell lung cancer cells to SN-38 and 5-FU without alteration to p53 expression levels.

    Science.gov (United States)

    Yan, Dongmei; Zheng, Xiaoliang; Tu, Linglan; Jia, Jing; Li, Qin; Cheng, Liyan; Wang, Xiaoju

    2015-01-01

    Merm1/Wbscr22 is a novel metastasis promoter that has been shown to be involved in tumor metastasis, viability and apoptosis. To the best of our knowledge, there are currently no studies suggesting the possible correlation between the expression of Merm1/Wbscr22 in tumor cells and chemosensitivity to antitumor agents. In the present study, two human non-small cell lung cancer cell lines, H1299 and H460, were used to investigate whether Merm1/Wbscr22 affects chemosensitivity to antitumor agents, including cisplatin (CDDP), doxorubicin (ADM), paclitaxel (PTX), mitomycin (MMC), 7-Ethyl-10-hydroxycamptothecin (SN-38; the active metabolite of camptothecin) and 5-fluorouracil (5-FU). Merm1/Wbscr22 knockdown cell lines (H1299-shRNA and H460-shRNA) and negative control cell lines (H1299-NC and H460-NC) were established by stable transfection, and the efficiency of Merm1/Wbscr22 knockdown was confirmed by western blotting, immunofluorescence microscopy and quantitative polymerase chain reaction. The results demonstrated that shRNA-mediated knockdown of Merm1/Wbscr22 did not affect cell proliferation in vitro and in vivo. The H460 cells harboring wild type p53 were markedly more sensitive to all six antitumor agents as compared with the p53-null H1299 cells. Downregulation of Merm1/Wbscr22 did not affect H1299 sensitivity to any of the six antitumor agents, whereas attenuated H460 sensitivity to SN-38 and 5-FU, without significant alteration in p53 at both mRNA and protein levels, was identified. The reduced H460 sensitivity to SN-38 was further confirmed in vivo. SN-38 demonstrated significant tumor growth inhibitory activity in both H460 and H460‑NC tumor xenograft models, but only marginally suppressed the H460-shRNA xenograft tumor growth. Furthermore, CDDP (4, 10, 15 µg/ml)-resistant human non-small lung cancer cells A549 (A549-CDDPr-4, 10, 15) expressed significant amounts of Merm1/Wbscr22 protein, as compared with the parental A549 cells. In conclusion, sh

  13. p53-Dependent transcriptional responses to interleukin-3 signaling.

    Directory of Open Access Journals (Sweden)

    Anissa M Jabbour

    Full Text Available p53 is critical in the normal response to a variety of cellular stresses including DNA damage and loss of p53 function is a common feature of many cancers. In hematological malignancies, p53 deletion is less common than in solid malignancies but is associated with poor prognosis and resistance to chemotherapy. Compared to their wild-type (WT counterparts, hematopoietic progenitor cells lacking p53 have a greater propensity to survive cytokine loss, in part, due to the failure to transcribe Puma, a proapoptotic Bcl-2 family member. Using expression arrays, we have further characterized the differences that distinguish p53(-/- cells from WT myeloid cells in the presence of Interleukin-3 (IL-3 to determine if such differences contribute to the increased clonogenicity and survival responses observed in p53(-/- cells. We show that p53(-/- cells have a deregulated intracellular signaling environment and display a more rapid and sustained response to IL-3. This was accompanied by an increase in active ERK1/2 and a dependence on an intact MAP kinase signaling pathway. Contrastingly, we find that p53(-/- cells are independent on AKT for their survival. Thus, loss of p53 in myeloid cells results in an altered transcriptional and kinase signaling environment that favors enhanced cytokine signaling.

  14. p53: Biology and role for cellular radiosensitivity

    International Nuclear Information System (INIS)

    Purpose: p53 is the most commonly mutated gene in human tumors with large impact on cellular biology and response to radiation. Many excellent reviews are available on various aspects but for several years none about the role of p53 for radiosensitivity. The latter is the aim of the present paper. Methods: Review of the literature. Results: p53 is a regulator of apoptosis mainly in hematopoetic tissue. In normal tissue and solid tumors presumably other functions have more impact on the cellular response. p53 controls cell-cycle progression after irradiation and also DNA-repair, namely homologous and non-homologous recombination. Mutations of p53 alter these functions which may be responsible for an enhanced cellular and tumor radioresistance. At present only few reports were able to show that under tightly controlled conditions loss of p53 wild-type function leads to enhanced radioresistance. A general proof is still lacking. Conclusion: The emerging picture in the year 2000 shows p53 as a central protein in a multi-enzyme multi-function network which is far from being fully understood. Although p53 appears to be a major regulator it is certainly not the unreplacable component the loss of which uniformly determines radioresistance. Only further understanding of modifiers and cooperators in the cell and in the specific tissue context will elucidate p53's role for radiosensitivity and radiotherapy. (orig.)

  15. p53 isoforms regulate astrocyte-mediated neuroprotection and neurodegeneration.

    Science.gov (United States)

    Turnquist, C; Horikawa, I; Foran, E; Major, E O; Vojtesek, B; Lane, D P; Lu, X; Harris, B T; Harris, C C

    2016-09-01

    Bidirectional interactions between astrocytes and neurons have physiological roles in the central nervous system and an altered state or dysfunction of such interactions may be associated with neurodegenerative diseases, such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). Astrocytes exert structural, metabolic and functional effects on neurons, which can be either neurotoxic or neuroprotective. Their neurotoxic effect is mediated via the senescence-associated secretory phenotype (SASP) involving pro-inflammatory cytokines (e.g., IL-6), while their neuroprotective effect is attributed to neurotrophic growth factors (e.g., NGF). We here demonstrate that the p53 isoforms Δ133p53 and p53β are expressed in astrocytes and regulate their toxic and protective effects on neurons. Primary human astrocytes undergoing cellular senescence upon serial passaging in vitro showed diminished expression of Δ133p53 and increased p53β, which were attributed to the autophagic degradation and the SRSF3-mediated alternative RNA splicing, respectively. Early-passage astrocytes with Δ133p53 knockdown or p53β overexpression were induced to show SASP and to exert neurotoxicity in co-culture with neurons. Restored expression of Δ133p53 in near-senescent, otherwise neurotoxic astrocytes conferred them with neuroprotective activity through repression of SASP and induction of neurotrophic growth factors. Brain tissues from AD and ALS patients possessed increased numbers of senescent astrocytes and, like senescent astrocytes in vitro, showed decreased Δ133p53 and increased p53β expression, supporting that our in vitro findings recapitulate in vivo pathology of these neurodegenerative diseases. Our finding that Δ133p53 enhances the neuroprotective function of aged and senescent astrocytes suggests that the p53 isoforms and their regulatory mechanisms are potential targets for therapeutic intervention in neurodegenerative diseases. PMID:27104929

  16. The p53 pathway in breast cancer

    OpenAIRE

    Gasco, Milena; Shami, Shukri; Crook, Tim

    2002-01-01

    p53 mutation remains the most common genetic change identified in human neoplasia. In breast cancer, p53 mutation is associated with more aggressive disease and worse overall survival. The frequency of mutation in p53 is, however, lower in breast cancer than in other solid tumours. Changes, both genetic and epigenetic, have been identified in regulators of p53 activity and in some downstream transcriptional targets of p53 in breast cancers that express wild-type p53. Molecular pathological an...

  17. Classical and novel roles of p53 and prospects for anticancer therapy

    OpenAIRE

    Fuster, José J.; Sanz-González, Silvia M.; Moll, Ute M.; Andrés, Vicente

    2007-01-01

    The tumor suppressor p53 is a transcription factor that is frequently inactivated in human tumors. Therefore,restoring its function has been considered an attractive approach to restrain cancer. Typically, p53-dependent growth arrest, senescence and apoptosis of tumor cells have been attributed to transcriptional activity of nuclear p53. Notably, wild-type p53 gain-of-function enhances cancer resistance in the mouse, but it also accelerates aging in some models, possibly due to altered p53...

  18. p53 isoform Δ113p53 is a p53 target gene that antagonizes p53 apoptotic activity via BclxL activation in zebrafish

    OpenAIRE

    Chen, Jun; Ng, Sok Meng; Chang, Changqing; Zhang, Zhenhai; Bourdon, Jean-Christophe; Lane, David P; Peng, Jinrong

    2009-01-01

    p53 is a well-known tumor suppressor and is also involved in processes of organismal aging and developmental control. A recent exciting development in the p53 field is the discovery of various p53 isoforms. One p53 isoform is human Δ133p53 and its zebrafish counterpart Δ113p53. These N-terminal-truncated p53 isoforms are initiated from an alternative p53 promoter, but their expression regulation and physiological significance at the organismal level are not well understood. We show here that ...

  19. Analysis of mutations in the p16/CDKN2A gene in sporadic and familial melanoma in the Polish population.

    Science.gov (United States)

    Lamperska, Katarzyna; Karezewska, Aldona; Kwiatkowska, Eliza; Mackiewicz, Andrzej

    2002-01-01

    Mutations in CDKN2A have been found in sporadic cutaneous malignant (CMM), in familial CMM and in other syndromes associated with melanoma. In this study DNA was obtained from 207 individuals and five cell lines. There were 157 CMM patients and 50 healthy members of melanoma patients families. The CMM group included patients with one or two melanoma cases in the family, families with dysplastic nevus syndrom (DNS) and patients with a spectrum of other types of cancers in the family. PCR-SSCP analysis and sequencing identified: six substitutions in codon 58 CGA/TGA (Arg/Stop), 16 substitutions GAC/GAT in codon 84 (Asp/Asp), six substitutions CGA/TGA in codon 148 (Arg/Thr), 14 substitutions G/C in 3'UTR and 4 double changes (two in codon 84 and 3'UTR; two in codon 148 and 3'UTR). The mutation identified in codon 58 was found in tissue only. Other substitutions were polymorphisms found in DNA from tissue and blood samples. Most of them were identified in sporadic CMM (six in codon 148 Ala/Thr, 12 in codon 84 Asp/Asp and six in 3'UTR). The frequency of the polymorphisms was also high in DNS and CMM/DNS families (four in codon 84 Asp/Asp and six in 3'UTR). No mutations or polymorphisms were found in CMM patients with one or two melanoma cases and CMM patients, with other cancers in family history. The analysis of the CDKN2A gene mutations in the Polish population demonstrated: (i) no germline mutations; (ii) a relatively high number of genetic changes in sporadic melanoma; (iii) a high number of polymorphisms in DNS and CMM/DNS families. PMID:12362978

  20. Biological activity and safety of adenoviral vector-expressed wild-type p53 after intratumoral injection in melanoma and breast cancer patients with p53-overexpressing tumors

    NARCIS (Netherlands)

    Dummer, R; Bergh, J; Karlsson, Y; Horovitz, JA; Mulder, NH; Huinin, DT; Burg, G; Hofbauer, G; Osanto, S

    2000-01-01

    p53 mutations are common genetic alterations in human cancer. Gene transfer of a wild-type (wt) p53 gene reverses the loss of normal p53 function in vitro and in vivo. A phase I dose escalation study of single intratumoral (i.t.) injection of a replication-defective adenoviral expression vector cont

  1. p53 in the DNA-Damage-Repair Process.

    Science.gov (United States)

    Williams, Ashley B; Schumacher, Björn

    2016-01-01

    The cells in the human body are continuously challenged by a variety of genotoxic attacks. Erroneous repair of the DNA can lead to mutations and chromosomal aberrations that can alter the functions of tumor suppressor genes or oncogenes, thus causing cancer development. As a central tumor suppressor, p53 guards the genome by orchestrating a variety of DNA-damage-response (DDR) mechanisms. Already early in metazoan evolution, p53 started controlling the apoptotic demise of genomically compromised cells. p53 plays a prominent role as a facilitator of DNA repair by halting the cell cycle to allow time for the repair machineries to restore genome stability. In addition, p53 took on diverse roles to also directly impact the activity of various DNA-repair systems. It thus appears as if p53 is multitasking in providing protection from cancer development by maintaining genome stability. PMID:27048304

  2. NSAIDs Modulate CDKN2A, TP53, and DNA Content Risk for Progression to Esophageal Adenocarcinoma

    OpenAIRE

    Galipeau, Patricia C.; Xiaohong Li; Blount, Patricia L.; Maley, Carlo C.; Sanchez, Carissa A.; Odze, Robert D.; Kamran Ayub; Rabinovitch, Peter S.; Vaughan, Thomas L.; Reid, Brian J.

    2007-01-01

    Editors' Summary Background. Normally, the cells in the human body divide only when extra cells are needed, after an injury, for example. Sometimes, however, cells accumulate genetic changes (mutations) that allow them to divide uncontrollably to form a disorganized mass or tumor. If these altered cells also acquire mutations that allow them to spread around the body, a malignant tumor or cancer results. Scientists have identified numerous genetic changes that occur in tumors and are now inve...

  3. Association of variants in CDKN2A/2B and CDKAL1 genes with gestational insulin sensitivity and disposition in pregnant Han Chinese women

    OpenAIRE

    Mei, Jie; Liao, Shunyao; Liu, Yunqiang; Tan, Yuande; Wang, Hailian; Liang, Yaming; Dong, Xianjue; Song, Wenzhong; Gan, Lu; Deng, Shaoping

    2015-01-01

    Aims/Introduction Variants in cell cycle regulation genes, CDKAL1 and CDKN2A/2B, have been suggested to be associated with type 2 diabetes, and also play a role in insulin procession in non-diabetic European individuals. Rs7754580 in CDKAL1 and rs7020996 in CDKN2A/2B were found to be associated with gestational diabetes in Chinese individuals. In order to understand the metabolism mechanism of greatly upregulated maternal insulin signaling during pregnancy and the pathogenesis of gestational ...

  4. p53 and its isoforms in cancer

    OpenAIRE

    Bourdon, J-C

    2007-01-01

    p53, p63 and p73 are members of the p53 gene family involved in development, differentiation and response to cellular stress. p53 gene is a transcription factor essential for the prevention of cancer formation. The p53 pathway is ubiquitously lost in human cancer either by p53 gene mutation (60% of cancers) or by lost of cell signalling upstream and downstream of p53 in the remaining cancers expressing WTp53 gene. As p53 pathway inactivation is a common denominator to all cancers, the underst...

  5. Acetylation Is Indispensable for p53 Activation

    OpenAIRE

    Tang, Yi; Zhao, Wenhui; Chen, Yue; Zhao, Yingming; Gu, Wei

    2008-01-01

    The activation of the tumor suppressor p53 facilitates the cellular response to genotoxic stress; however, the p53 response can only be executed if its interaction with its inhibitor Mdm2 is abolished. There have been conflicting reports on the question of whether p53 posttranslational modifications, such as phosphorylation or acetylation, are essential or only play a subtle, fine-tuning role in the p53 response. Thus, it remains unclear whether p53 modification is absolutely required for its...

  6. Regulation of Mutant p53 Protein Expression

    OpenAIRE

    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 e...

  7. Arginine methylation regulates the p53 response

    DEFF Research Database (Denmark)

    Jansson, Martin; Durant, Stephen T; Cho, Er-Chieh;

    2008-01-01

    Activation of the p53 tumour suppressor protein in response to DNA damage leads to apoptosis or cell-cycle arrest. Enzymatic modifications are widely believed to affect and regulate p53 activity. We describe here a level of post-translational control that has an important functional consequence on...... of p53. Furthermore, PRMT5 depletion triggers p53-dependent apoptosis. Thus, methylation on arginine residues is an underlying mechanism of control during the p53 response....

  8. p53 isoforms, Δ133p53 and p53β, are endogenous regulators of replicative cellular senescence

    OpenAIRE

    Fujita, Kaori; Mondal, Abdul M.; Horikawa, Izumi; Nguyen, Giang H.; Kumamoto, Kensuke; Sohn, Jane J.; Bowman, Elise D.; Mathe, Ewy A.; Schetter, Aaron J.; Pine, Sharon R.; Ji, Helen; Vojtesek, Borivoj; Bourdon, Jean-Christophe; Lane, David P; Harris, Curtis C.

    2009-01-01

    The finite proliferative potential of normal human cells leads to replicative cellular senescence, which is a critical barrier to tumour progression in vivo1–3. We show that human p53 isoforms (Δ133p53 and p53β)4 constitute an endogenous regulatory mechanism for p53-mediated replicative senescence. Induced p53β and diminished Δ133p53 were associated with replicative senescence, but not oncogene-induced senescence, in normal human fibroblasts. The replicatively senescent fibroblasts also expre...

  9. Distinct pattern of p53 mutations in bladder cancer

    DEFF Research Database (Denmark)

    Spruck, C H; Rideout, W M; Olumi, A F;

    1993-01-01

    A distinct mutational spectrum for the p53 tumor suppressor gene in bladder carcinomas was established in patients with known exposures to cigarette smoke. Single-strand conformational polymorphism analysis of exons 5 through 8 of the p53 gene showed inactivating mutations in 16 of 40 (40%) bladder....... The results suggest that, although cigarette smoke exposure may not significantly alter the kinds of mutations sustained in the p53 gene, it may act to increase the extent of DNA damage per mutagenic event....

  10. Skp2B overexpression alters a prohibitin-p53 axis and the transcription of PAPP-A, the protease of insulin-like growth factor binding protein 4.

    Directory of Open Access Journals (Sweden)

    Harish Chander

    Full Text Available BACKGROUND: We previously reported that the degradation of prohibitin by the SCF(Skp2B ubiquitin ligase results in a defect in the activity of p53. We also reported that MMTV-Skp2B transgenic mice develop mammary gland tumors that are characterized by an increased proteolytic cleavage of the insulin-like growth factor binding protein 4 (IGFBP-4, an inhibitor of IGF signaling. However, whether a link exists between a defect in p53 activity and proteolysis of IGFBP-4 was not established. METHODS AND RESULTS: We analyzed the levels of pregnancy-associated plasma protein A (PAPP-A, the protease of IGFBP-4, in MMTV-Skp2B transgenic mice and found that PAPP-A levels are elevated. Further, we found a p53 binding site in intron 1 of the PAPP-A gene and that both wild type and mutant p53 bind to this site. However, binding of wild type p53 results in the transcriptional repression of PAPP-A, while binding of mutant p53 results in the transcriptional activation of PAPP-A. Since MMTV-Skp2B mice express wild type p53 and yet show elevated levels of PAPP-A, at first, these observations appeared contradictory. However, further analysis revealed that the defect in p53 activity in Skp2B overexpressing cells does not only abolish the activity of wild type of p53 but actually mimics that of mutant p53. Our results suggest that in absence of prohibitin, the half-life of p53 is increased and like mutant p53, the conformation of p53 is denatured. CONCLUSIONS: These observations revealed a novel function of prohibitin as a chaperone of p53. Further, they suggest that binding of denatured p53 in intron 1 causes an enhancer effect and increases the transcription of PAPP-A. Therefore, these findings indicate that the defect in p53 function and the increased proteolysis of IGFBP-4, we had observed, represent two components of the same pathway, which contributes to the oncogenic function of Skp2B.

  11. Berberine alters epigenetic modifications, disrupts microtubule network, and modulates HPV-18 E6-E7 oncoproteins by targeting p53 in cervical cancer cell HeLa: a mechanistic study including molecular docking.

    Science.gov (United States)

    Saha, Santu Kumar; Khuda-Bukhsh, Anisur Rahman

    2014-12-01

    Increased evidence of chemo-resistance, toxicity and carcinogenicity necessitates search for alternative approaches for determining next generation cancer therapeutics and targets. We therefore tested the efficacy of plant alkaloid berberine on human papilloma virus (HPV) -18 positive cervical cancer cell HeLa systematically-involving certain cellular, viral and epigenetic factors. We observed disruptions of microtubule network and changes in membrane topology due to berberine influx through confocal and atomic force microscopies (AFM). We examined nuclear uptake, internucleosomal DNA damages, mitochondrial membrane potential (MMP) alterations and cell migration assays to validate possible mode of cell death events. Analytical data on interactions of berberine with pBR322 through fourier transform infrared (FTIR) and gel migration assay strengthen berberine׳s biologically significant DNA binding abilities. We measured cellular uptake, DNA ploidy and DNA strand-breaks through fluorescence activated cell sorting (FACS). To elucidate epigenetic modifications, in support of DNA binding associated processes, if any, we conducted methylation-specific restriction enzyme (RE) assay, methylation specific-PCR (MSP) and expression studies of histone proteins. We also analyzed differential interactions and localization of cellular tumor suppressor p53 and viral oncoproteins HPV-18 E6-E7 through siRNA approach. We further made in-silico approaches to determine possible binding sites of berberine on histone proteins. Overall results indicated cellular uptake of berberine through cell membrane depolarization causing disruption of microtubule networks and its biological DNA binding abilities that probably contributed to epigenetic modifications. Results of modulation in p53 and viral oncoproteins HPV-18 E6-E7 by berberine further proved its potential as a promising chemotherapeutic agent in cervical cancer. PMID:25448308

  12. p53-Dependent G1 arrest and p53-independent apoptosis influence the radio biologic response of glioblastoma

    International Nuclear Information System (INIS)

    Purpose: Loss of the p53 tumor suppressor gene has been associated with tumor progression, disease relapse, poor response to antineoplastic therapy, and poor prognosis in many malignancies. We have investigated the contribution of p53-mediated radiation-induced apoptosis and G1 arrest to the well described radiation resistance of glioblastoma multiforme (GM) cells. Methods and Materials: Radiation survival in vitro was quantitated using linear quadratic and repair-saturation mathematical models. Isogenic derivatives of glioblastoma cells differing only in their p53 status were generated using a retroviral vector expressing a dominant negative mutant of p53. Radiation-induced apoptosis was assayed by Flourescence-activated cell sorter (FACS) analysis, terminal deoxynucleotide transferase labeling technique, and chromatin morphology. Cells were synchronized in early G1 phase and mitotic and labeling indices were measured. Results: Radiation-induced apoptosis of GM cells was independent of functional wild-type p53 (wt p53). Decreased susceptibility to radiation-induced apoptosis was associated with lower α values characterizing the shoulder of the clonogenic radiation survival curve. Using isogenic GM cells differing only in their p53 activity, we found that a p53-mediated function, radiation-induced G1 arrest, could also influence the value of α and clonogenic radiation resistance. Inactivation of wt p53 function by a dominant negative mutant of p53 resulted in a significantly diminished α value with no alteration in cellular susceptibility to radiation-induced apoptosis. The clonal derivative U87-LUX.8 expressing a functional wt p53 had an α (Gy-1) value of 0.609, whereas the isogenic clonal derivative U87-175.4 lacking wt p53 function had an α (Gy-1) value of 0.175. Conclusion: We conclude that two distinct cellular responses to radiation, p53-independent apoptosis and p53-dependent G1-arrest, influence radiobiological parameters that characterize the

  13. p53 Acetylation: Regulation and Consequences

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Sara M. [Department of Pharmacology, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Medical Scientist Training Program, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Quelle, Dawn E., E-mail: dawn-quelle@uiowa.edu [Department of Pharmacology, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Medical Scientist Training Program, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Department of Pathology, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States)

    2014-12-23

    Post-translational modifications of p53 are critical in modulating its tumor suppressive functions. Ubiquitylation, for example, plays a major role in dictating p53 stability, subcellular localization and transcriptional vs. non-transcriptional activities. Less is known about p53 acetylation. It has been shown to govern p53 transcriptional activity, selection of growth inhibitory vs. apoptotic gene targets, and biological outcomes in response to diverse cellular insults. Yet recent in vivo evidence from mouse models questions the importance of p53 acetylation (at least at certain sites) as well as canonical p53 functions (cell cycle arrest, senescence and apoptosis) to tumor suppression. This review discusses the cumulative findings regarding p53 acetylation, with a focus on the acetyltransferases that modify p53 and the mechanisms regulating their activity. We also evaluate what is known regarding the influence of other post-translational modifications of p53 on its acetylation, and conclude with the current outlook on how p53 acetylation affects tumor suppression. Due to redundancies in p53 control and growing understanding that individual modifications largely fine-tune p53 activity rather than switch it on or off, many questions still remain about the physiological importance of p53 acetylation to its role in preventing cancer.

  14. p53 Acetylation: Regulation and Consequences

    International Nuclear Information System (INIS)

    Post-translational modifications of p53 are critical in modulating its tumor suppressive functions. Ubiquitylation, for example, plays a major role in dictating p53 stability, subcellular localization and transcriptional vs. non-transcriptional activities. Less is known about p53 acetylation. It has been shown to govern p53 transcriptional activity, selection of growth inhibitory vs. apoptotic gene targets, and biological outcomes in response to diverse cellular insults. Yet recent in vivo evidence from mouse models questions the importance of p53 acetylation (at least at certain sites) as well as canonical p53 functions (cell cycle arrest, senescence and apoptosis) to tumor suppression. This review discusses the cumulative findings regarding p53 acetylation, with a focus on the acetyltransferases that modify p53 and the mechanisms regulating their activity. We also evaluate what is known regarding the influence of other post-translational modifications of p53 on its acetylation, and conclude with the current outlook on how p53 acetylation affects tumor suppression. Due to redundancies in p53 control and growing understanding that individual modifications largely fine-tune p53 activity rather than switch it on or off, many questions still remain about the physiological importance of p53 acetylation to its role in preventing cancer

  15. p53 Acetylation: Regulation and Consequences

    Directory of Open Access Journals (Sweden)

    Sara M. Reed

    2014-12-01

    Full Text Available Post-translational modifications of p53 are critical in modulating its tumor suppressive functions. Ubiquitylation, for example, plays a major role in dictating p53 stability, subcellular localization and transcriptional vs. non-transcriptional activities. Less is known about p53 acetylation. It has been shown to govern p53 transcriptional activity, selection of growth inhibitory vs. apoptotic gene targets, and biological outcomes in response to diverse cellular insults. Yet recent in vivo evidence from mouse models questions the importance of p53 acetylation (at least at certain sites as well as canonical p53 functions (cell cycle arrest, senescence and apoptosis to tumor suppression. This review discusses the cumulative findings regarding p53 acetylation, with a focus on the acetyltransferases that modify p53 and the mechanisms regulating their activity. We also evaluate what is known regarding the influence of other post-translational modifications of p53 on its acetylation, and conclude with the current outlook on how p53 acetylation affects tumor suppression. Due to redundancies in p53 control and growing understanding that individual modifications largely fine-tune p53 activity rather than switch it on or off, many questions still remain about the physiological importance of p53 acetylation to its role in preventing cancer.

  16. Comparison Study of MS-HRM and Pyrosequencing Techniques for Quantification of APC and CDKN2A Gene Methylation

    Science.gov (United States)

    Migheli, Francesca; Stoccoro, Andrea; Coppedè, Fabio; Wan Omar, Wan Adnan; Failli, Alessandra; Consolini, Rita; Seccia, Massimo; Spisni, Roberto; Miccoli, Paolo; Mathers, John C.; Migliore, Lucia

    2013-01-01

    There is increasing interest in the development of cost-effective techniques for the quantification of DNA methylation biomarkers. We analyzed 90 samples of surgically resected colorectal cancer tissues for APC and CDKN2A promoter methylation using methylation sensitive-high resolution melting (MS-HRM) and pyrosequencing. MS-HRM is a less expensive technique compared with pyrosequencing but is usually more limited because it gives a range of methylation estimates rather than a single value. Here, we developed a method for deriving single estimates, rather than a range, of methylation using MS-HRM and compared the values obtained in this way with those obtained using the gold standard quantitative method of pyrosequencing. We derived an interpolation curve using standards of known methylated/unmethylated ratio (0%, 12.5%, 25%, 50%, 75%, and 100% of methylation) to obtain the best estimate of the extent of methylation for each of our samples. We observed similar profiles of methylation and a high correlation coefficient between the two techniques. Overall, our new approach allows MS-HRM to be used as a quantitative assay which provides results which are comparable with those obtained by pyrosequencing. PMID:23326336

  17. Effect of p53 genotype on gene expression profiles in murine liver

    International Nuclear Information System (INIS)

    The tumor suppressor protein p53 is a key regulatory element in the cell and is regarded as the 'guardian of the genome'. Much of the present knowledge of p53 function has come from studies of transgenic mice in which the p53 gene has undergone a targeted deletion. In order to provide additional insight into the impact on the cellular regulatory networks associated with the loss of this gene, microarray technology was utilized to assess gene expression in tissues from both the p53-/- and p53+/- mice. Six male mice from each genotype (p53+/+, p53+/-, and p53-/-) were humanely killed and the tissues processed for microarray analysis. The initial studies have been performed in the liver for which the Dunnett test revealed 1406 genes to be differentially expressed between p53+/+ and p53+/- or between p53+/+ and p53-/- at the level of p ≤ 0.05. Both genes with increased expression and decreased expression were identified in p53+/- and in p53-/- mice. Most notable in the gene list derived from the p53+/- mice was the significant reduction in p53 mRNA. In the p53-/- mice, not only was there reduced expression of the p53 genes on the array, but genes associated with DNA repair, apoptosis, and cell proliferation were differentially expressed, as expected. However, altered expression was noted for many genes in the Cdc42-GTPase pathways that influence cell proliferation. This may indicate that alternate pathways are brought into play in the unperturbed liver when loss or reduction in p53 levels occurs

  18. p53 gene mutations, p53 protein accumulation and compartmentalization in colorectal adenocarcinoma.

    OpenAIRE

    Bosari, S.; Viale, G.; Roncalli, M; Graziani, D.; Borsani, G; Lee, A. K.; Coggi, G.

    1995-01-01

    p53 accumulation may occur in the nucleus and/or cytoplasm of neoplastic cells. Cytoplasmic accumulation has been reported to be an unfavorable, but not established, prognostic indicator in colorectal cancer. Different types of p53 intracellular compartmentalization could depend either on p53 gene mutations or on the interaction with p53 protein ligands. The purposes of our study were (1) to assess whether the different patterns of p53 accumulation are selectively associated with p53 mutation...

  19. p53 Acetylation: Regulation and Consequences

    OpenAIRE

    Reed, Sara M.; Quelle, Dawn E.

    2014-01-01

    Post-translational modifications of p53 are critical in modulating its tumor suppressive functions. Ubiquitylation, for example, plays a major role in dictating p53 stability, subcellular localization and transcriptional vs. non-transcriptional activities. Less is known about p53 acetylation. It has been shown to govern p53 transcriptional activity, selection of growth inhibitory vs. apoptotic gene targets, and biological outcomes in response to diverse cellular insults. Yet recent in vivo ev...

  20. Non-p53 p53RE binding protein, a human transcription factor functionally analogous to P53

    OpenAIRE

    Zeng, Xiaoya; Levine, Arnold J.; Lu, Hua

    1998-01-01

    The transactivation activity of the p53 tumor suppressor protein is critical for regulating cell growth and apoptosis. We describe the identification of a transcription factor that is functionally similar to p53 and contains the same DNA binding and transcription activities specific for the p53 responsive DNA element (p53RE). This protein was highly purified through chromatography from HeLa cell extracts. The purified protein was able to bind specifically to the p53RE derived from a p21waf1 p...

  1. Constant rate of p53 tetramerization in response to DNA damage controls the p53 response

    OpenAIRE

    Gaglia, Giorgio; Lahav, Galit

    2014-01-01

    The dynamics of the tumor suppressor protein p53 have been previously investigated in single cells using fluorescently tagged p53. Such approach reports on the total abundance of p53 but does not provide a measure for functional p53. We used fluorescent protein-fragment complementation assay (PCA) to quantify in single cells the dynamics of p53 tetramers, the functional units of p53. We found that while total p53 increases proportionally to the input strength, p53 tetramers are formed in cell...

  2. p53: Biology and role for cellular radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Dahm-Daphi, J. [Hamburg Univ. (Germany). Abt. fuer Strahlentherapie und Onkologie

    2000-06-01

    Purpose: p53 is the most commonly mutated gene in human tumors with large impact on cellular biology and response to radiation. Many excellent reviews are available on various aspects but for several years none about the role of p53 for radiosensitivity. The latter is the aim of the present paper. Methods: Review of the literature. Results: p53 is a regulator of apoptosis mainly in hematopoetic tissue. In normal tissue and solid tumors presumably other functions have more impact on the cellular response. p53 controls cell-cycle progression after irradiation and also DNA-repair, namely homologous and non-homologous recombination. Mutations of p53 alter these functions which may be responsible for an enhanced cellular and tumor radioresistance. At present only few reports were able to show that under tightly controlled conditions loss of p53 wild-type function leads to enhanced radioresistance. A general proof is still lacking. Conclusion: The emerging picture in the year 2000 shows p53 as a central protein in a multi-enzyme multi-function network which is far from being fully understood. Although p53 appears to be a major regulator it is certainly not the unreplacable component the loss of which uniformly determines radioresistance. Only further understanding of modifiers and cooperators in the cell and in the specific tissue context will elucidate p53's role for radiosensitivity and radiotherapy. (orig.) [German] Hintergrund: p53 ist das am haeufigsten mutierte Gen in menschlichen Tumoren mit grossem Einfluss auf die zellulaere Biologie und Strahlenantwort. Viele ausgezeichnete Uebersichten sind verfuegbar, aber seit Jahren keine, die die Rolle von p53 fuer die Strahlenempfindlichkeit beleuchtet. Dies ist das Ziel der vorliegenden Arbeit. Methode: Literaturuebersicht. Ergebnis: p53 ist ein Regulator der Apoptose in haematopoetischen Gewerben. Im uebrigen Normalgewebe und in soliden Tumoren haben andere Funktionen groessere Bedeutung fuer die Zellantwort. Nach

  3. Allele Specific p53 Mutant Reactivation

    OpenAIRE

    Yu, Xin; Vazquez, Alexei; Levine, Arnold J.; Carpizo, Darren R.

    2012-01-01

    Rescuing the function of mutant p53 protein is an attractive cancer therapeutic strategy. Using the NCI anticancer drug screen data, we identified two compounds from the thiosemicarbazone family that manifest increased growth inhibitory activity in mutant p53 cells, particularly for the p53R175 mutant. Mechanistic studies reveal that NSC319726 restores WT structure and function to the p53R175 mutant. This compound kills p53R172H knock-in mice with extensive apoptosis and inhibits xenograft tu...

  4. Updates on p53: modulation of p53 degradation as a therapeutic approach

    OpenAIRE

    Dey, A; Verma, C S; LANE, D. P.

    2008-01-01

    The p53 pathway is aberrant in most human tumours with over 50% expressing mutant p53 proteins. The pathway is critically controlled by protein degradation. Here, we discuss the latest developments in the search for small molecules that can modulate p53 pathway protein stability and restore p53 activity for cancer therapy.

  5. Cellular functions of p53 and p53 gene family members p63 and p73

    Directory of Open Access Journals (Sweden)

    Nadir Koçak

    2011-12-01

    Full Text Available p53 is a transcription factor that regulates multiple cellular processes that are also important in cellular fates such as cell cycle arrest or programmed cell death. Induction of growth arrest or cell death by p53 prevents the replication of damaged DNA and proliferation of genetically abnormal cells. Therefore, inactivation of p53 by mutation or deletion is also important in ensuring the cellular homeostasis. However, studies showed that p53 deficient mice and cells such as Saos-2 cells are maintaining their life. This situation suggests that p53-related proteins might compensate the functions of p53 in p53 deficient organisms. The identification of two p53-related proteins, p63 and p73 revealed the transcription of p53 responsive genes in p53 deficient organisms. Both p63 and p73 proteins have high homology with the p53 protein and share some of the functions of p53. In contrast to p53, p63 and p73 rarely mutated in human cancers. Here we studied to summarize the current information about the p53 and other p53-related proteins, p63 and p73 that are included into the p53 gene family.

  6. Tumor suppressor p53: analysis of wild-type and mutant p53 complexes.

    OpenAIRE

    Milner, J; Medcalf, E A; Cook, A. C.

    1991-01-01

    It has been suggested that the dominant effect of mutant p53 on tumor progression may reflect the mutant protein binding to wild-type p53, with inactivation of suppressor function. To date, evidence for wild-type/mutant p53 complexes involves p53 from different species. To investigate wild-type/mutant p53 complexes in relation to natural tumor progression, we sought to identify intraspecific complexes, using murine p53. The mutant phenotype p53-246(0) was used because this phenotype is immuno...

  7. High-resolution array copy number analyses for detection of deletion, gain, amplification and copy-neutral LOH in primary neuroblastoma tumors: Four cases of homozygous deletions of the CDKN2A gene

    Directory of Open Access Journals (Sweden)

    Kogner Per

    2008-07-01

    Full Text Available Abstract Background Neuroblastoma is a very heterogeneous pediatric tumor of the sympathetic nervous system showing clinically significant patterns of genetic alterations. Favorable tumors usually have near-triploid karyotypes with few structural rearrangements. Aggressive stage 4 tumors often have near-diploid or near-tetraploid karyotypes and structural rearrangements. Whole genome approaches for analysis of genome-wide copy number have been used to analyze chromosomal abnormalities in tumor samples. We have used array-based copy number analysis using oligonucleotide single nucleotide polymorphisms (SNP arrays to analyze the chromosomal structure of a large number of neuroblastoma tumors of different clinical and biological subsets. Results Ninety-two neuroblastoma tumors were analyzed with 50 K and/or 250 K SNP arrays from Affymetrix, using CNAG3.0 software. Thirty percent of the tumors harbored 1p deletion, 22% deletion of 11q, 26% had MYCN amplification and 45% 17q gain. Most of the tumors with 1p deletion were found among those with MYCN amplification. Loss of 11q was most commonly seen in tumors without MYCN amplification. In the case of MYCN amplification, two types were identified. One type displayed simple continuous amplicons; the other type harbored more complex rearrangements. MYCN was the only common gene in all cases with amplification. Complex amplification on chromosome 12 was detected in two tumors and three different overlapping regions of amplification were identified. Two regions with homozygous deletions, four cases with CDKN2A deletions in 9p and one case with deletion on 3p (the gene RBMS3 were also detected in the tumors. Conclusion SNP arrays provide useful tools for high-resolution characterization of significant chromosomal rearrangements in neuroblastoma tumors. The mapping arrays from Affymetrix provide both copy number and allele-specific information at a resolution of 10–12 kb. Chromosome 9p, especially the gene

  8. The CDKN2A G500 allele is more frequent in GBM patients with no defined telomere maintenance mechanism tumors and is associated with poorer survival.

    Directory of Open Access Journals (Sweden)

    Janice A Royds

    Full Text Available Prognostic markers for glioblastoma multiforme (GBM are important for patient management. Recent advances have identified prognostic markers for GBMs that use telomerase or the alternative lengthening of telomeres (ALT mechanism for telomere maintenance. Approximately 40% of GBMs have no defined telomere maintenance mechanism (NDTMM, with a mixed survival for affected individuals. This study examined genetic variants in the cyclin-dependent kinase inhibitor 2A (CDKN2A gene that encodes the p16(INK4a and p14(ARF tumor suppressors, and the isocitrate dehydrogenase 1 (IDH1 gene as potential markers of survival for 40 individuals with NDTMM GBMs (telomerase negative and ALT negative by standard assays, 50 individuals with telomerase, and 17 individuals with ALT positive tumors. The analysis of CDKN2A showed NDTMM GBMs had an increased minor allele frequency for the C500G (rs11515 polymorphism compared to those with telomerase and ALT positive GBMs (p = 0.002. Patients with the G500 allele had reduced survival that was independent of age, extent of surgery, and treatment. In the NDTMM group G500 allele carriers had increased loss of CDKN2A gene dosage compared to C500 homozygotes. An analysis of IDH1 mutations showed the R132H mutation was associated with ALT positive tumors, and was largely absent in NDTMM and telomerase positive tumors. In the ALT positive tumors cohort, IDH1 mutations were associated with a younger age for the affected individual. In conclusion, the G500 CDKN2A allele was associated with NDTMM GBMs from older individuals with poorer survival. Mutations in IDH1 were not associated with NDTMM GBMs, and instead were a marker for ALT positive tumors in younger individuals.

  9. p53 expression in biopsies from children with Langerhans cell histiocytosis

    DEFF Research Database (Denmark)

    Bank, Micha I; Lundegaard, Pia Rengtved; Carstensen, Henrik;

    2002-01-01

    single-system lesions only without relapse, whereas others develop fatal multiorgan disease. The expression of p53 tumor suppressor gene product detected immunohistochemically can be used as a guideline to alterations in DNA repair control and apoptosis. The authors have chosen to analyze p53 expression...... diagnosis of LCH based on CD1a positivity. The slides were stained with p53 antibody and semiquantitatively evaluated using a grading system from 1 to 5 as an estimate for 0% to 20%, 20% to 40%, 40% to 60%, 60% to 80%, and 80% to 100% p53-positive for pathologic Langerhans cells (pLC), respectively. RESULTS......: The p53 protein was expressed in various degrees in pLC in all lesions. The degree of p53 expression could not be correlated to either clinical manifestation or outcome. CONCLUSIONS: An increased expression of p53 in pLC indicates an altered DNA repair control with or without abnormal control of...

  10. The effect of adenovirus expressing wild-type p53 on 5-fiuorouracil chemosensitivity is related to p53 status in pancreatic cancer cell lines

    Institute of Scientific and Technical Information of China (English)

    Sven Eisold; Michael Linnebacher; Eduard Ryschich; Dalibor Antolovic; Ulf Hinz; Ernst Klar; Jan Schmidt

    2004-01-01

    AIM: There are conflicting data about p53 function on cellular sensitivity to the cytotoxic action of 5-fluorouracil (5-FU).Therefore the objective of this study was to determine the combined effects of adenovirus-mediated wild-type (wt) p53gene transfer and 5-FU chemotherapy on pancreatic cancer cells with different p53 gene status.METHODS: Human pancreatic cancer cell lines Capan-1p53mut,Capan-2p53wt, FAMPACp53mut, PANC1p53mut, and rat pancreatic cancer cell lines ASp53wt and DSL6Ap53null were used for in vitro studies. Following infection with different ratios of Adp53-particles (MOI) in combination with 5-FU, proliferation of tumor cells and apoptosis were quantified by cell proliferation assay (WST-1) and FACS (PI-staining). In addition, DSL6A syngeneic pancreatic tumor cells were inoculated subcutaneously in to Lewis rats for in vivo studies.Tumor size, apoptosis (TUNEL) and survival were determined.RESULTS: Ad-p53 gene transfer combined with 5-FU significantly inhibited tumor cell proliferation and substantially enhanced apoptosis in all four cell lines with an alteration in the p53 gene compared to those two cell lines containing wt-p53. In vivo experiments showed the most effective tumor regression in animals treated with Ad-p53 plus 5-FU. Both in vitro and in vivo analyses revealed that a sublethal dose of Ad-p53 augmented the apoptotic response induced by 5-FU.CONCLUSION: Our results suggest that Ad-p53 may synergistically enhance 5-FU-chemosensitivity most strikingly in pancreatic cancer cells lacking p53 function. These findings illustrate that the anticancer efficacy of this combination treatment is dependent on the p53 gene status of the target tumor cells.

  11. Transcriptional upregulation of restin by p53

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Restin, belonging to the melanoma-associated antigen superfamily, was firstly cloned from the differentiated HL-60 cells when induced by all-trans retinoic acid ( ATRA ) in our lab. Our previous results showed that restin might be correlated to cell cycle arrest. Due to the importance of p53 in the regulation of cell growth and the relationship between p53 and ATRA, we tried to test the relationship between p53 and restin. Firstly, transfection results showed that p53 was able to upregulate the expression of restin at the transcriptional level when p53 was transfected into eukaryotic cells. Secondly, the bioinformatics analysis revealed that the upstream sequence (about 2 kb) from the first ATG of the ORF of restin gene contained a p53 binding site. In order to confirm that p53 was involved in the transcriptional regulation of restin, we cloned the upstream sequence of restin and constructed the promoter luciferase reporter system. From the luciferase activity, we demonstrated that the promoter of restin gene could be induced by ATRA. Then, another two luciferase reporter plasmids driven by the reporter of restin with no (RP?p53-luc) or mutant (mRP-luc) p53 binding site were constructed to see the regulation of restin by p53. Results showed that the transcriptional upregulation of restin gene was not due to the putative p53 binding site on the upstream of restin gene. We proposed that p53 upregulated restin transcription through an indirect way rather than direct interaction with the cis-activating element of the restin promoter.

  12. Transcriptional upregulation of restin by p53

    Institute of Scientific and Technical Information of China (English)

    WANG RuiHua; LU Fan; FU HaiYan; WU YouSheng; YANG GuoDong; ZHAO WenMing; Zhao ZhongLiang

    2007-01-01

    Restin, belonging to the melanoma-associated antigen superfamily, was firstly cloned from the differentiated HL-60 cells when induced by all-trans retinoic acid ( ATRA ) in our lab. Our previous results showed that restin might be correlated to cell cycle arrest. Due to the importance of p53 in the regulation of cell growth and the relationship between p53 and ATRA, we tried to test the relationship between p53 and restin. Firstly, transfection results showed that p53 was able to upregulate the expression of restin at the transcriptional level when p53 was transfected into eukaryotic cells. Secondly, the bioinformatics analysis revealed that the upstream sequence (about 2 kb) from the first ATG of the ORF of restin gene contained a p53 binding site. In order to confirm that p53 was involved in the transcriptional regulation of restin, we cloned the upstream sequence of restin and constructed the promoter luciferase reporter system. From the luciferase activity, we demonstrated that the promoter of restin gene could be induced by ATRA. Then, another two luciferase reporter plasmids driven by the reporter of restin with no (RP△p53-luc) or mutant (mRP-luc) p53 binding site were constructed to see the regulation of restin by p53. Results showed that the transcriptional upregulation of restin gene was not due to the putative p53 binding site on the upstream of restin gene. We proposed that p53 upregulated restin transcription through an indirect way rather than direct interaction with the cis-activating element of the restin promoter.

  13. ROS and p53: versatile partnership

    OpenAIRE

    Liu, Bin; Chen, Yumin; St. Clair, Daret K.

    2008-01-01

    The tumor suppressor protein p53 is a redox active transcription factor that organizes and directs cellular responses in the face of a variety of stresses that lead to genomic instability. One of the most important questions in the study of p53 is how selective transactivation of certain p53 target genes is achieved. Reactive oxygen species (ROS), generated by cells as products or byproducts, can function either as signaling molecules or as cellular toxicants. Cellular generation of ROS is ce...

  14. Identification of p53 and Its Isoforms in Human Breast Carcinoma Cells

    OpenAIRE

    Zorka Milićević; Vladan Bajić; Lada Živković; Jelena Kasapović; Uroš Andjelković; Biljana Spremo-Potparević

    2014-01-01

    In breast carcinoma, disruption of the p53 pathway is one of the most common genetic alterations. The observation that the p53 can express multiple protein isoforms adds a novel level of complexity to the outcome of p53 mutations. p53 expression was analysed by Western immunoblotting and immunohistochemistry using monoclonal antibodies DO-7, Pab240, and polyclonal antiserum CM-1. The more frequently p53-positive nuclear staining has been found in the invasive breast tumors. One of the most in...

  15. G9a and Glp Methylate Lysine 373 in the Tumor Suppressor p53*

    OpenAIRE

    Huang, Jing; Dorsey, Jean; Chuikov, Sergei; Xinyue ZHANG; Jenuwein, Thomas; Reinberg, Danny; Berger, Shelley L.

    2010-01-01

    The tumor suppressor p53 is regulated by numerous post-translational modifications. Lysine methylation has recently emerged as a key post-translational modification that alters the activity of p53. Here, we describe a novel lysine methylation site in p53 that is carried out by two homologous histone methyltransferases, G9a and Glp. G9a and Glp specifically methylate p53 at Lys373, resulting mainly in dimethylation. During DNA damage, the overall level of p53 modified at Lys373me2 does not inc...

  16. HCV NS5A abrogates p53 protein function by interfering with p53-DNA binding

    Institute of Scientific and Technical Information of China (English)

    Guo-Zhong Gong; Yong-Fang Jiang; Yan He; Li-Ying Lai; Ying-Hua Zhu; Xian-Shi Su

    2004-01-01

    AIM: To evaluate the inhibition effect of HCV NS5A on p53 transactivation on p21 promoter and explore its possible mechanism for influencing p53 function.METHODS: p53 function of transactivation on p21 promoter was studied with a luciferase reporter system in which the luciferase gene is driven by p21 promoter, and the p53-DNA binding ability was observed with the use of electrophoretic mobility-shift assay (EMSA). Lipofectin mediated p53 or HCV NS5A expression vectors were used to transfect hepatoma cell lines to observe whether HCV NS5A could abrogate the binding ability of p53 to its specific DNA sequence and p53 transactivation on p21 promoter.Western blot experiment was used for detection of HCV NS5A and p53 proteins expression.RESULTS: Relative luciferase activity driven by p21 promoter increased significantly in the presence of endogenous p53 protein. Compared to the control group, exogenous p53 protein also stimulated p21 promoter driven luciferase gene expression in a dose-dependent way. HCV NS5A protein gradually inhibited both endogenous and exogenous p53 transactivation on p21 promoter with increase of the dose of HCV NS5A expression plasmid. By the experiment of EMSA, we could find p53 binding to its specific DNA sequence and, when co-transfected with increased dose of HCV NS5A expression vector, the p53 binding affinity to its DNA gradually decreased and finally disappeared. Between the Huh 7 cells transfected with p53 expression vector alone or co-transfected with HCV NS5A expression vector, there was no difference in the p53 protein expression.CONCLUSION: HCV NS5A inhibits p53 transactivation on p21 promoter through abrogating p53 binding affinity to its specific DNA sequence. It does not affect p53 protein expression.

  17. The p53-dependent radioadaptive response

    Science.gov (United States)

    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.

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

    OpenAIRE

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

    2015-01-01

    Background A comprehensive search for DNA methylated genes identified candidate tumor suppressor genes that have been proven to be involved in the apoptotic process of the p53 pathway. In this study, we investigated p53 mutation in relation to such epigenetic alteration in primary gastric cancer. Methods The methylation profiles of the 3 genes: PGP9.5, NMDAR2B, and CCNA1, which are involved in the p53 tumor suppressor pathway in combination with p53 mutation were examined in 163 primary gastr...

  19. p53: The Janus of autophagy?

    OpenAIRE

    Levine, Beth; Abrams, John

    2008-01-01

    The autophagy pathway functions in adaptation to nutrient stress and tumour suppression. The p53 tumour suppressor, previously thought to positively regulate autophagy, may also inhibit it. This dual interplay between p53 and autophagy regulation is enigmatic, but may underlie key aspects of metabolism and cancer biology.

  20. p53 mutant breast cancer patients expressing p53γ have as good a prognosis as wild-type p53 breast cancer patients

    OpenAIRE

    Bourdon, Jean-Christophe; Khoury, Marie,; Diot, Alexandra; Baker, Lee; Fernandes, Kenneth; Aoubala, Mustapha; Quinlan, Philip; Purdie, Colin; Jordan, Lee; Prats, Anne-Catherine; Lane, David; Thompson, Alastair

    2011-01-01

    International audience INTRODUCTION: Normal function of the p53 network is lost in most cancers, often through p53 mutation. The clinical impact of p53 mutations in breast cancer remains uncertain, especially where p53 isoforms may modify the effects of these p53 mutations. METHODS: Expression of p53β and p53γ isoforms, the isoforms identified in normal breast tissue, was detected by reverse transcription polymerase chain reaction from a cohort of 127 primary breast tumours. Expression of ...

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

    International Nuclear Information System (INIS)

    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 (As3+) induced apoptosis and cell cycle arrest in a dose-dependent manner in both p53+/+ and p53-/- 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-/- cells than in the p53+/+ 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 As3+. A significant alteration in the Nrf2-mediated oxidative stress response pathway was found in both genotypes. In p53+/+ MEFs, As3+ induced p53-dependent gene expression alterations in DNA damage and cell cycle regulation genes. However, in the p53-/- MEFs, As3+ 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

  2. Distinct HIC1-SIRT1-p53 Loop Deregulation in Lung Squamous Carcinoma and Adenocarcinoma Patients

    Directory of Open Access Journals (Sweden)

    Ruo-Chia Tseng

    2009-08-01

    Full Text Available A HIC1-SIRT1-p53 circular loop in which hypermethylation in cancer 1 (HIC1 represses the transcription of SIRT1 that deacetylates and inactivates p53 thus leading to HIC1 inactivation has been identified in cell and animal models. However, the alteration and prognostic effects of HIC1-SIRT1-p53 circular loop have never been demonstrated in human cancer patients. We examine the HIC1-SIRT1-p53 alterations in 118 lung cancer patients to define their etiological roles in tumorigenesis. We found that patients with lung squamous cell carcinoma with low p53 acetylation and SIRT1 expression mostly showed low HIC1 expression, confirming deregulation of HIC1-SIRT1-p53 circular loop in the clinical model. Interestingly, the expression of deleted in breast cancer 1 (DBC1, which blocks the interaction between SIRT1 deacetylase and p53, led to acetylated p53 in patients with lung adenocarcinoma. However, epigenetic alteration of HIC1 promoter by posttranslational modifications of histones and promoter hypermethylation favoring the compacted chromatin production attenuated the transcriptional induction by acetylated p53. Importantly, lung cancer patients with altered HIC1-SIRT1-p53 circular regulation showed poor prognosis. Our data show the first valid clinical evidence of the deregulation of HIC1-SIRT1-p53 loop in lung tumorigenesis and prognosis. Distinct status of p53 acetylation/deacetylation and HIC1 alteration mechanism result from different SIRT1-DBC1 control and epigenetic alteration in lung squamous cell carcinoma and lung adenocarcinoma.

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

    Energy Technology Data Exchange (ETDEWEB)

    Otozai, Shinji [Department of Otorhinolaryngology and Head and Neck Surgery, Osaka University School of Medicine, Osaka 565-0871 (Japan); Ishikawa-Fujiwara, Tomoko [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Oda, Shoji [Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8562 (Japan); Kamei, Yasuhiro [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Ryo, Haruko [Nomura Project, National Institute of Biomedical Innovation, Osaka 565-0085 (Japan); Sato, Ayuko [Department of Pathology, Hyogo College of Medicine, Hyogo 663-8501 (Japan); Nomura, Taisei [Nomura Project, National Institute of Biomedical Innovation, Osaka 565-0085 (Japan); Mitani, Hiroshi [Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8562 (Japan); Tsujimura, Tohru [Department of Pathology, Hyogo College of Medicine, Hyogo 663-8501 (Japan); Inohara, Hidenori [Department of Otorhinolaryngology and Head and Neck Surgery, Osaka University School of Medicine, Osaka 565-0871 (Japan); Todo, Takeshi, E-mail: todo@radbio.med.osaka-u.ac.jp [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-02-15

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

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

    International Nuclear Information System (INIS)

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

  5. Cellular functions of p53 and p53 gene family members p63 and p73

    OpenAIRE

    Nadir Koçak; İbrahim Halil Yıldırım; Seval Cing Yıldırım

    2011-01-01

    p53 is a transcription factor that regulates multiple cellular processes that are also important in cellular fates such as cell cycle arrest or programmed cell death. Induction of growth arrest or cell death by p53 prevents the replication of damaged DNA and proliferation of genetically abnormal cells. Therefore, inactivation of p53 by mutation or deletion is also important in ensuring the cellular homeostasis. However, studies showed that p53 deficient mice and cells such as Saos-2 cells are...

  6. The heme–p53 interaction: Linking iron metabolism to p53 signaling and tumorigenesis

    OpenAIRE

    Shen, Jia; Sheng, Xiangpeng; Chang, ZeNan; Wu, Qian; Xie, Dong; Wang, Fudi; HU, Ronggui

    2014-01-01

    Recently, we reported that heme binds to tumor suppressor p53 protein (TP53, best known as p53) and promotes its nuclear export and cytosolic degradation, whereas iron chelation stabilizes p53 protein and suppresses tumors in a p53-dependent manner. This not only provides mechanistic insights into tumorigenesis associated with iron excess, but also helps guide the administration of chemotherapy based on iron deprivation in the clinic.

  7. Immune response to p53 is dependent upon p53/HSP70 complexes in breast cancers.

    OpenAIRE

    Davidoff, A.M.; Iglehart, J D; Marks, J R

    1992-01-01

    Overexpression of the p53 protein, resulting from gene mutations that increase protein stability, has been detected in greater than 25% of primary human breast cancers. In addition, approximately 10% of breast cancer patients have circulating antibodies to the p53 protein. In this study, the anti-p53 humoral response is correlated with the presence and type of mutant p53 protein expressed in the tumor. In a series of 60 breast cancer patients, 0 of 30 tumors with normal, low-level p53 express...

  8. Effects of long term exposure to the mycotoxin fumonisin B1 in p53 heterozygous and p53 homozygous transgenic mice.

    Science.gov (United States)

    Bondy, Genevieve; Mehta, Rekha; Caldwell, Don; Coady, Laurie; Armstrong, Cheryl; Savard, Marc; Miller, J David; Chomyshyn, Emily; Bronson, Roni; Zitomer, Nicholas; Riley, Ronald T

    2012-10-01

    The fungal toxin fumonisin B1 (FB1) is a potential human carcinogen based on evidence of renal carcinogenicity in rats and hepatocarcinogenicity in mice. The toxicity and carcinogenicity of FB1 is linked to ceramide synthase inhibition. Based on this mechanism of action and on lack of evidence of genotoxicity, FB1 is considered a non-genotoxic carcinogen. The p53 heterozygous (p53+/-) mouse is a cancer-prone model used for carcinogenesis. The effects of chronic dietary FB1 exposure were characterized in p53+/- mice to confirm non-genotoxicity using a model which is more sensitive to genotoxic than non-genotoxic carcinogens and to clarify the relationship between p53 expression, altered sphingolipid metabolism, and FB1-induced carcinogenesis. Responses to FB1 were similar in p53+/- and p53+/+ mice after 26 weeks exposure to 0, 5, 50 or 150 mg FB1/kg diet, supporting a non-genotoxic mechanism of action. Hepatic adenomas and cholangiomas were observed in mice exposed to 150 mg/kg FB1. For a 10% increase in hepatic megalocytosis, the estimated 95% lower confidence limit of the benchmark dose (BMDL10) ranged from 0.15 and 1.11 mg FB1/kg bw/day. Based on similar responses in p53+/- and p53+/+ mice, p53 and related pathways play a secondary role in responses to FB1 toxicity and carcinogenesis. PMID:22841953

  9. A neurogenic tumor containing a low-grade malignant peripheral nerve sheath tumor (MPNST) component with loss of p16 expression and homozygous deletion of CDKN2A/p16: a case report showing progression from a neurofibroma to a high-grade MPNST

    OpenAIRE

    Tajima, Shogo; Koda, Kenji

    2015-01-01

    Development of malignant peripheral nerve sheath tumors (MPNSTs) is a stepwise process that involves the alteration of many cell cycle regulators and the double inactivation of the NF1 gene. Inactivation of the TP53 gene and deletion of the CDKN2A/p16 gene are known to play an important role in the process. Herein, we present a 19-year-old man with a familial history of neurofibromatosis type 1, in whom the tumor arose from the intercostal nerve and showed 3 components: a neurofibroma, a low-...

  10. Global genomic profiling reveals an extensive p53-regulated autophagy program contributing to key p53 responses

    OpenAIRE

    Kenzelmann Broz, Daniela; Spano Mello, Stephano; Bieging, Kathryn T.; Jiang, Dadi; Rachel L Dusek; Brady, Colleen A.; Sidow, Arend; Attardi, Laura D.

    2013-01-01

    To gain new insights into p53 biology, Kenzelmann Broz et al. used high-throughput sequencing to analyze global p53 transcriptional networks in primary mouse embryo fibroblasts in response to DNA damage. This approach identified autophagy genes as direct p53 target genes. p53-induced autophagy was important for both p53-dependent apoptosis and transformation suppression by p53. These data highlight an intimate connection between p53 and autophagy and suggest that autophagy contributes to p53-...

  11. Glycerol restores the p53 function in human lingual cancer cells bearing mutant p53

    International Nuclear Information System (INIS)

    Mutations in p53, tumor suppressor gene, have recently been shown to have an impact on the clinical course of several human tumors, including head and neck cancers. The genetic status of the p53 gene has been focused on as the most important candidate among various cancer-related genes for prognosis-predictive assays of cancer therapy. We examined the restoration of radiation- or cisplatin (CDDP)-induced p53-dependent apoptosis in human lingual cancer cells. The results suggest that glycerol is effective in inducing a conformational change of p53 and restoring normal function of mutant p53, leading to enhanced radiosensitivity or chemosensitivity through the induction of apoptosis. We have also represented the same results in vivo as in vitro. Thus, this novel tool for enhancement of radiosensitivity or chemosensitivity in cancer cells bearing m p53 may be applicable for p53-targeted cancer therapy. (author)

  12. Constant denaturant gel electrophoresis as a rapid screening technique for p53 mutations.

    OpenAIRE

    Børresen, A.L.; Hovig, E; Smith-Sørensen, B; Malkin, D; Lystad, S; Andersen, T.I.; Nesland, J. M.; Isselbacher, K J; Friend, S H

    1991-01-01

    At present, mutation of the p53 gene appears to be the most common genetic alteration found in human cancers. These mutations can occur within many different regions of the gene. We have developed a modification of denaturing gradient gel electrophoresis termed "constant denaturant gel electrophoresis" (CDGE), which provides a rapid and sensitive method to screen the four conserved regions within the p53 gene where the majority of p53 mutations have been reported. The sensitivity of CDGE was ...

  13. Transcriptional Activation by Wild-Type But Not Transforming Mutants of the p53 Anti-Oncogene

    OpenAIRE

    Raycroft, Loretta; Wu, Hongyun; Lozano, Guillermina

    1990-01-01

    The protein encoded by the wild-type p53 proto-oncogene has been shown to suppress transformation, whereas certain mutations that alter p53 become transformation competent. Fusion proteins between p53 and the GAL4 DNA binding domain were made to anchor p53 to a DNA target sequence and to allow measurement of transcriptional activation of a reporter plasmid. The wild-type p53 stimulated transcription in this assay, but two transforming mutations in p53 were unable to act as transcriptional act...

  14. P53 overexpression and outcome of radiation therapy in head and neck cancers

    International Nuclear Information System (INIS)

    Experimental studies have implicated the wild type p53 in cellular response to radiation. Whether altered p53 function can lead to changes in clinical radiocurability remains an area of ongoing study. This study was performed to investigate whether any correlation between change of p53 and outcome of curative radiation therapy in patients with head and neck cancers. Immunohistochemical analysis with a mouse monoclonal antibody (D0-7) specific for human p53 was used to detect to overexpression of protein in formalin fixed, paraffin-embedded tumor sample from 55 head and neck cancer patients treated with curative radiation therapy (median dose of 7020 cGy) from February 1988 to March 1996 at St. Mary's Hospital. Overexpression of p53 was correlated with locoregional control and survival using Kaplan-Meier method. A Cox regression multivariate analysis was performed that included all clinical variables and status of p53 expression. Thirty-seven (67.2%) patients showed overexpression of p53 by immunohistochemical staining in their tumor. One hundred percent of oral cavity, 76% of laryngeal, 66.7% of oropharyngeal, 66.7% of hypopharyngeal cancer showed p53 overexpression (p=0.05). The status of p53 had significant relationship with stage of disease (p=0.03) and history of smoking (p=0.001). The overexpression of p53 was not predictive of response rate to radiation therapy. The locoregional control was not significantly affected by p53 status. Overexpression of p53 didn't have any prognostic implication for disease free survival and overall survival. Primary site and stage of disease were significant prognostic factors for survival. The p53 overexpression as detected by immunohistochemical staining had significant correlation with stage, primary site of disease and smoking habit of patients. The p53 overexpression didn't have any predictive value for outcome of curative radiation therapy in a group of head and neck cancers

  15. Expression of p53 in endometrial polyps with special reference to the p53 signature.

    Science.gov (United States)

    Sho, Tomoko; Hachisuga, Toru; Kawagoe, Toshinori; Urabe, Rie; Kurita, Tomoko; Kagami, Seiji; Shimajiri, Shohei; Fujino, Yoshihisa

    2016-07-01

    We herein examined the significance of the p53 expression in endometrial polyps (EMPs). A total of 133 EMPs, including 62 premenopausal and 71 postmenopausal women with EMP, were immunohistochemically studied for the expression of estrogen receptor (ER)-alpha, Ki-67 and p53. Apoptotic cells were identified using a TUNEL assay. A DNA sequence analysis of TP53 exons 5 to 9 was performed. Among the premenopausal EMPs, a multivariate analysis showed the labeling index (LI) for Ki-67 to correlate significantly with that for p53 (PEMPs, the LI for Ki-67 correlated significantly with that for apoptosis (PEMPs (mean age: 70.2 years). The median Ki-67 index for the p53S was 7%, with no significant difference from that of the glands of the postmenopausal EMPs without the p53S (P=0.058). The median apoptotic index for the p53S was 0%, which was significantly lower than that of the postmenopausal EMPs without the p53S (P=0.002). Two of four p53Ss showed TP53 mutations according to the DNA sequence analysis. The presence of the p53S is not rare in postmenopausal EMPs with an advanced age. Among postmenopausal EMPs, the LI of Ki-67 significantly correlates with that of apoptosis. However, such a positive correlation between the LI of Ki-67 and apoptosis is not observed in p53S. PMID:26727623

  16. Effects of Δ40p53, an isoform of p53 lacking the N-terminus, on transactivation capacity of the tumor suppressor protein p53

    International Nuclear Information System (INIS)

    The p53 protein is expressed as multiple isoforms that differ in their N- and C-terminus due to alternative splicing, promoter or codon initiation usage. Δ40p53 lacks the first 39 residues containing the main transcriptional activation domain, resulting from initiation of translation at AUG +40 in fully spliced p53 mRNA or in a specific variant mRNA retaining intron 2. Overexpression of Δ40p53 antagonizes wild-type p53 in vitro. However, animal models of Δ40p53 in mouse or Zebrafish have shown complex phenotypes suggestive of p53-dependent growth suppressive effects. We have co-transfected expression vectors for p53 and Δ40p53 in p53-null cell lines Saos-2 and H1299 to show that Δ40p53 forms mixed oligomers with p53 that bind to DNA and modulate the transcription of a generic p53-dependent reporter gene. In H1299 cells, co-expression of the two proteins induced a decrease in transcription with amplitude that depended upon the predicted composition of the hetero-tetramer. In Saos-2, a paradoxical effect was observed, with a small increase in activity for hetero-tetramers predicted to contain 1 or 2 monomers of Δ40p53 and a decrease at higher Δ40p53/p53 ratios. In this cell line, co-transfection of Δ40p53 prevented Hdm2-mediated degradation of p53. Δ40p53 modulates transcriptional activity by interfering with the binding of Hdm2 to hetero-tetramers containing both Δ40p53 and p53. These results provide a basis for growth suppressive effects in animal models co-expressing roughly similar levels of p53 and Δ40p53

  17. The tumor suppressor p53 regulates its own transcription.

    OpenAIRE

    Deffie, A; H. Wu; Reinke, V.; Lozano, G.

    1993-01-01

    The ability of p53 to suppress transformation correlates with its ability to activate transcription. To identify targets of p53 transactivation, we examined the p53 promoter itself. Northern (RNA) analysis and transient transfection experiments showed that p53 transcriptionally regulated itself. A functionally inactive mutant p53 could not regulate the p53 promoter. Deletion analysis of the p53 promoter delineated sequences between +22 and +67 as being critical for regulation. Electrophoretic...

  18. p53 Response to Ultrasound: Preliminary Observations in MCF7 Human Breast Cancer Cells

    Science.gov (United States)

    Burns, Janis M.; Campbell, Paul A.

    2011-09-01

    Mutated p53 can be found in approximately half of all human cancers. Strategies which seek to restore, or at least exercise a level of external control over, p53 functionality are thus potentially useful as adjuncts to therapy. Here, we report our preliminary measurements in this area, and demonstrate that short-burst pulsed ultrasound can indeed affect p53 activity. Specifically, we have observed that expression of the p53 protein can be regulated in the period immediately following low intensity short pulse (millisecond) ultrasound exposure, and that altered activity levels return to basal levels over a 24 hour period post-insonation.

  19. Expression of p53 protein in precursor lesions and adenocarcinoma of human pancreas.

    OpenAIRE

    Boschman, C. R.; Stryker, S.; Reddy, J K; M.S. Rao

    1994-01-01

    To evaluate the incidence and stage at which p53 alterations occur in human pancreatic carcinogenesis, we examined primary and metastatic carcinomas, carcinoma in situ, and hyperplastic lesions with and without atypia for p53 protein overexpression by immunohistochemical procedure. Overexpression of p53 was observed in 40% (10/25) of primary tumors, 29% (2/7) of metastatic tumors, 36% (5/14) of carcinoma in situ, and 35% (6/17) of hyperplastic lesions. These results suggest that p53 protein o...

  20. Genome wide expression profiling of p53 regulated miRNAs in neuroblastoma

    OpenAIRE

    Rihani, Ali; Van Goethem, Alan; Ongenaert, Maté; De Brouwer, Sara; Volders, Pieter-Jan; Agarwal, Saurabh; De Preter, Katleen; Mestdagh, Pieter; Shohet, Jason; Speleman, Frank; Vandesompele, Jo; VAN MAERKEN, TOM

    2015-01-01

    Restoration of the antitumor activity of p53 could offer a promising approach for the treatment of neuroblastoma. MicroRNAs (miRNAs) are important mediators of p53 activity, but their role in the p53 response has not yet been comprehensively addressed in neuroblastoma. Therefore, we set out to characterize alterations in miRNA expression that are induced by p53 activation in neuroblastoma cells. Genome-wide miRNA expression analysis showed that miR-34a-5p, miR-182-5p, miR-203a, miR-222-3p, an...

  1. THE EXPRESSION OF P53 PROTEIN AND P21WAFl/cipl/sdil IN GASTRIC CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective To study the relation along p53, p21 protein, p21 gene and their clinical significances in 40 gastric comparing with normal gastric tissues.Methods In this study, the p53 and p21 protein were investigated in 40 gastric carcinomas using IHC(Immunohistochemistry). At the same time, the possible presence of p21 gene mutation was also analyzed by silver staining PCR-SSCP method.Results The abnormal expression of p53 and p21 protein occurs only in gastric carcinoma; The expression of p53 protein and p21 is not related to the clinico pathological features. There was relationship between the expression of p53 protein and p21 protein. In 40 cases of gastric carcinoma, single strand conformational polymorphism of PCR product for p21 gene in tumor tissue shows no altered band or mobility shifting.Conclusion The abnormal expression of p53 and p21 protein occurs only in gastric carcinoma and is not related to the clinicopathological features. The expression of p21 protein is related to that of p53 protein. The mutation of p21 gene was not found in all of 40 tumor specimens. This suggests that p21 alteration in gastric carcinoma is caused through the inactivation of p53 protein rather than through intragenic mutation of the p21 gene itself.Using drugs which can stimulate p21 gene is a new method to cure gastric cancer with mutation-p53 protein.

  2. Wild-type p53 and p73 negatively regulate expression of proliferation related genes.

    Science.gov (United States)

    Scian, M J; Carchman, E H; Mohanraj, L; Stagliano, K E R; Anderson, M A E; Deb, D; Crane, B M; Kiyono, T; Windle, B; Deb, S P; Deb, S

    2008-04-17

    When normal cells come under stress, the wild-type (WT) p53 level increases resulting in the regulation of gene expression responsible for growth arrest or apoptosis. Here we show that elevated levels of WT p53 or its homologue, p73, inhibit expression of a number of cell cycle regulatory and growth promoting genes. Our analysis also identified a group of genes whose expression is differentially regulated by WT p53 and p73. We have infected p53-null H1299 human lung carcinoma cells with recombinant adenoviruses expressing WT p53, p73 or beta-galactosidase, and have undertaken microarray hybridization analyses to identify genes whose expression profile is altered by p53 or p73. Quantitative real-time PCR verified the repression of E2F-5, centromere protein A and E, minichromosome maintenance proteins (MCM)-2, -3, -5, -6 and -7 and human CDC25B after p53 expression. 5-Fluorouracil treatment of colon carcinoma HCT116 cells expressing WT p53 results in a reduction of the cyclin B2 protein level suggesting that DNA damage may indeed cause repression of these genes. Transient transcriptional assays verified that WT p53 repressed promoters of a number of these genes. Interestingly, a gain-of-function p53 mutant instead upregulated a number of these promoters in transient transfection. Using promoter deletion mutants of MCM-7 we have found that WT p53-mediated repression needs a minimal promoter that contains a single E2F site and surrounding sequences. However, a single E2F site cannot be significantly repressed by WT p53. Many of the genes identified are also repressed by p21. Thus, our work shows that WT p53 and p73 repress a number of growth-related genes and that in many instances this repression may be through the induction of p21. PMID:17982488

  3. p53-directed translational control can shape and expand the universe of p53 target genes.

    Science.gov (United States)

    Zaccara, S; Tebaldi, T; Pederiva, C; Ciribilli, Y; Bisio, A; Inga, A

    2014-10-01

    The increasing number of genome-wide transcriptome analyses focusing on p53-induced cellular responses in many cellular contexts keeps adding to the already numerous p53-regulated transcriptional networks. To investigate post-transcriptional controls as an additional dimension of p53-directed gene expression responses, we performed a translatome analysis through polysomal profiling on MCF7 cells upon 16 hours of doxorubicin or nutlin-3a treatment. The comparison between the transcriptome and the translatome revealed a considerable level of uncoupling, characterized by genes whose transcription variations did not correlate with translation variations. Interestingly, uncoupled genes were associated with apoptosis, DNA and RNA metabolism and cell cycle functions, suggesting that post-transcriptional control can modulate classical p53-regulated responses. Furthermore, even for well-established p53 targets that were differentially expressed both at the transcriptional and translational levels, quantitative differences between the transcriptome, subpolysomal and polysomal RNAs were evident. As we searched mechanisms underlying gene expression uncoupling, we identified the p53-dependent modulation of six RNA-binding proteins, where hnRNPD (AUF1) and CPEB4 are direct p53 transcriptional targets, whereas SRSF1, DDX17, YBX1 and TARDBP are indirect targets (genes modulated preferentially in the subpolysomal or polysomal mRNA level) modulated at the translational level in a p53-dependent manner. In particular, YBX1 translation appeared to be reduced by p53 via two different mechanisms, one related to mTOR inhibition and the other to miR-34a expression. Overall, we established p53 as a master regulator of translational control and identified new p53-regulated genes affecting translation that can contribute to p53-dependent cellular responses. PMID:24926617

  4. p53-directed translational control can shape and expand the universe of p53 target genes

    OpenAIRE

    Zaccara, S; Tebaldi, T; Pederiva, C; Ciribilli, Y; Bisio, A.; Inga, A

    2014-01-01

    The increasing number of genome-wide transcriptome analyses focusing on p53-induced cellular responses in many cellular contexts keeps adding to the already numerous p53-regulated transcriptional networks. To investigate post-transcriptional controls as an additional dimension of p53-directed gene expression responses, we performed a translatome analysis through polysomal profiling on MCF7 cells upon 16 hours of doxorubicin or nutlin-3a treatment. The comparison between the transcriptome and ...

  5. Estrogen receptor prevents p53-dependent apoptosis in breast cancer

    OpenAIRE

    Bailey, Shannon T.; Shin, Hyunjin; Westerling, Thomas; Liu, Xiaole Shirley; Brown, Myles

    2012-01-01

    More than two-thirds of breast cancers express the estrogen receptor (ER) and depend on estrogen for growth and survival. Therapies targeting ER function, including aromatase inhibitors that block the production of estrogens and ER antagonists that alter ER transcriptional activity, play a central role in the treatment of ER+ breast cancers of all stages. In contrast to ER− breast cancers, which frequently harbor mutations in the p53 tumor suppressor, ER+ breast cancers are predominantly wild...

  6. Loss of LSD1 (lysine-specific demethylase 1) suppresses growth and alters gene expression of human colon cancer cells in a p53- and DNMT1(DNA methyltransferase 1)-independent manner

    OpenAIRE

    Jin, Lihua; Hanigan, Christin L.; Wu, Yu; Wang, Wei; Park, Ben Ho; Woster, Patrick M.; Casero, Robert A.

    2012-01-01

    Epigenetic silencing of gene expression is important in cancer. Aberrant DNA CpG island hypermethylation and histone modifications are involved in the aberrant silencing of tumour-suppressor genes. LSD1 (lysine-specific demethylase 1) is a H3K4 (histone H3 Lys4) demethylase associated with gene repression and is overexpressed in multiple cancer types. LSD1 has also been implicated in targeting p53 and DNMT1 (DNA methyltransferase 1), with data suggesting that the demethylating activity of LSD...

  7. Genome-scale functional analysis of the human genes modulating p53 activity by regulating MDM2 expression in a p53-independent manner.

    Science.gov (United States)

    Kim, Dong Min; Choi, Seung-Hyun; Yeom, Young Il; Min, Sang-Hyun; Kim, Il-Chul

    2016-09-16

    MDM2, a critical negative regulator of p53, is often overexpressed in leukemia, but few p53 mutations are found, suggesting that p53-independent MDM2 expression occurs due to alterations in MDM2 upstream regulators. In this study, a high MDM2 transcription level was observed (41.17%) regardless of p53 expression in patient with acute myeloid leukemia (AML). Therefore, we performed genome-scale functional screening of the human genes modulating MDM2 expression in a p53-independent manner. We searched co-expression profiles of genes showing a positive or negative pattern with MDM2 expression in a DNA microarray database, selected1089 links, and composed a screening library of 368 genes. Using MDM2 P1 and P2 promoter-reporter systems, we screened clones regulating MDM2 transcriptions in a p53-independent manner by overexpression. Nine clones from the screening library showed enhanced MDM2 promoter activity and MDM2 expression in p53-deficient HCT116 cells. Among them, six clones, including NTRK2, GNA15, SFRS2, EIF5A, ELAVL1, and YWHAB mediated MAPK signaling for expressing MDM2. These results indicate that p53-independent upregulation of MDM2 by increasing selected clones may lead to oncogenesis in AML and that MDM2-modulating genes are novel potential targets for AML treatment. PMID:27524244

  8. Suppression of glucosylceramide synthase restores p53-dependent apoptosis in mutant p53 cancer cells

    OpenAIRE

    Liu, Yong-Yu; Patwardhan, Gauri A.; Bhinge, Kaustubh; Gupta, Vineet; Gu, Xin; Jazwinski, S. Michal

    2011-01-01

    Tumor suppressor p53 plays an essential role in protecting cells from malignant transformation by inducing cell cycle arrest and apoptosis. Mutant p53 that is detected in over 50% cases of cancers not only loses its role in suppressing of tumor but also gains oncogenic function. Strategies to convert mutant p53 into wild-type of p53 have been suggested for cancer prevention and treatment, but they face a variety of challenges. Here we report an alternate approach that involves suppression of ...

  9. Viral Oncoproteins Discriminate between p53 and the p53 Homolog p73

    OpenAIRE

    Marin, Maria Carmen; Jost, Christine A.; Irwin, Meredith S; DeCaprio, James A.; Caput, Daniel; William G Kaelin

    1998-01-01

    p73 is a recently identified member of the p53 family. Previously it was shown that p73 can, when overproduced in p53-defective tumor cells, activate p53-responsive promoters and induce apoptosis. In this report we describe the generation of anti-p73 monoclonal antibodies and confirm that two previously described p73 isoforms are produced in mammalian cells. Furthermore, we show that these two isoforms can bind to canonical p53 DNA-binding sites in electrophoretic mobility shift assays. Despi...

  10. Urodele p53 tolerates amino acid changes found in p53 variants linked to human cancer

    Directory of Open Access Journals (Sweden)

    Villiard Éric

    2007-09-01

    Full Text Available Abstract Background Urodele amphibians like the axolotl are unique among vertebrates in their ability to regenerate and their resistance to develop cancers. It is unknown whether these traits are linked at the molecular level. Results Blocking p53 signaling in axolotls using the p53 inhibitor, pifithrin-α, inhibited limb regeneration and the expression of p53 target genes such as Mdm2 and Gadd45, suggesting a link between tumor suppression and regeneration. To understand this relationship we cloned the p53 gene from axolotl. When comparing its sequence with p53 from other organisms, and more specifically human we observed multiple amino acids changes found in human tumors. Phylogenetic analysis of p53 protein sequences from various species is in general agreement with standard vertebrate phylogeny; however, both mice-like rodents and teleost fishes are fast evolving. This leads to long branch attraction resulting in an artefactual basal emergence of these groups in the phylogenetic tree. It is tempting to assume a correlation between certain life style traits (e.g. lifespan and the evolutionary rate of the corresponding p53 sequences. Functional assays of the axolotl p53 in human or axolotl cells using p53 promoter reporters demonstrated a temperature sensitivity (ts, which was further confirmed by performing colony assays at 37°C. In addition, axolotl p53 was capable of efficient transactivation at the Hmd2 promoter but has moderate activity at the p21 promoter. Endogenous axolotl p53 was activated following UV irradiation (100 j/m2 or treatment with an alkylating agent as measured using serine 15 phosphorylation and the expression of the endogenous p53 target Gadd45. Conclusion Urodele p53 may play a role in regeneration and has evolved to contain multiple amino acid changes predicted to render the human protein defective in tumor suppression. Some of these mutations were probably selected to maintain p53 activity at low temperature. However

  11. p53 regulation and activity in mouse embryonic stem cells

    OpenAIRE

    Solozobova, Valeriya

    2010-01-01

    P53 is a tumour development p53. The aim of this work was to study the regulation of p53 in embryonic stem cells and its activation in response to DNA damage. p53 was found that p53 becomes transcriptionally active in ES cells after DNA damage. Embryonic stem cells contain a relatively high amount of p53 protein and p53 RNA. After differentiation p53 level is rapidly downregulated. The high abundance of p53 in undifferentiated ES cells is a result of enhanced translation.

  12. IGFBP3 Promoter Methylation in Colorectal Cancer: Relationship with Microsatellite Instability, CpG Island Methylator Phenotype, p53

    Directory of Open Access Journals (Sweden)

    Takako Kawasaki

    2007-12-01

    Full Text Available Insulin-like growth factor binding protein 3 (IGFBP3, which is induced by wild-type p53, regulates IGF and interacts with the TGF-β pathway. IGFBP3 promoter methylation may occur in colorectal cancer with or without the CpG island methylator phenotype (CIMP, which is associated with microsatellite instability (MSI and TGFBR2 mutation. We examined the relationship between IGFBP3 methylation, p53 expression, CIMP and MSI in 902 population-based colorectal cancers. Utilizing real-time PCR (MethyLight, we quantified promoter methylation in IGFBP3 and eight other CIMP-high-specific promoters (CACNA1G, CDKN2A, CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1. IGFBP3 methylation was far more frequent in non-MSI-high CIMP-high tumors (85% = 35/41 than in MSI-high CIMPhigh (49% = 44/90, P < .0001, MSI-high non-CIMP-high (17% = 6/36, P < .0001, non-MSI-high non-CIMP-high tumors (22% = 152/680, P < .0001. Among CIMPhigh tumors, the inverse relationship between MSI and IGFBP3 methylation persisted in p53-negative tumors (P < .0001, but not in p53-positive tumors. IGFBP3 methylation was associated inversely with TGFBR2 mutation in MSI-high non-CIMP-high tumors (P = .02. In conclusion, IGFBP3 methylation is inversely associated with MSI in CIMP-high colorectal cancers, this relationship is limited to p53-negative tumors. Our data suggest complex relationship between global genomic/epigenomic phenomena (such as MSI/ CIMP, single molecular events (e.g., IGFBP3 methylation, TP53 mutation, TGFBR2 mutation, the related pathways.

  13. Δ122p53, a mouse model of Δ133p53α, enhances the tumor-suppressor activities of an attenuated p53 mutant

    OpenAIRE

    Slatter, T L; Hung, N. Van; Bowie, S; Campbell, H.; Rubio, C; Speidel, D; Wilson, M.; Baird, M.; Royds, J. A.; Braithwaite, A W

    2015-01-01

    Growing evidence suggests the Δ133p53α isoform may function as an oncogene. It is overexpressed in many tumors, stimulates pathways involved in tumor progression, and inhibits some activities of wild-type p53, including transactivation and apoptosis. We hypothesized that Δ133p53α would have an even more profound effect on p53 variants with weaker tumor-suppressor capability. We tested this using a mouse model heterozygous for a Δ133p53α-like isoform (Δ122p53) and a p53 mutant with weak tumor-...

  14. p53 Gene and Tumorigenesis%p53基因与肿瘤形成

    Institute of Scientific and Technical Information of China (English)

    韩涛; 杨德吉

    2008-01-01

    肿瘤抑制基因的研究已经成为继癌基因之后肿瘤遗传学、分子生物学领域的前沿和热点,尤其是抑癌基因p53越来越被人们重视.研究表明正常的p53,又称野生型p53,在细胞损伤后的修复过程中发挥重要作用.正常p53的功能像"分子警察"一样监视着基因组DNA的完整性.在细胞发生DNA损伤时,p53蛋白能使细胞分裂终止在G1/S期,以使细胞有足够的时间修复损伤,恢复正常状态.若不能修复,野生型p53还能启动细胞的凋亡过程从而引发细胞的程序性死亡,阻止具有癌变倾向的突变细胞产生.而突变型p53基因会导致肿瘤的发生,大多数肿瘤与p53的突变有关.文章着重阐述了p53的表达与突变、p53的稳定调节及p53的转录调控等.

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

    OpenAIRE

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

    2011-01-01

    Wild-type p53 is a stress-responsive tumor suppressor and potent growth inhibitor. Genotoxic stresses (e.g. ionizing and UV 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 fashion. Nutlin occupies the p53-binding pocket of MDM2, activating p53 by blocking the p53-MDM2 interaction. Because Nutlin neither binds p53 directl...

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

    Science.gov (United States)

    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.

  17. Peran p53 Sebagai Jalur Kritis pada Mekanisme Kontrol Siklus Sel Sebagai Pencegah Terjadinya Kanker Mulut

    Directory of Open Access Journals (Sweden)

    Herlia Nur Istindiah

    2015-09-01

    Full Text Available In cell cycle control, p53 acts as an emergency brake, where its important checkpoint function is to maintain the genome integrity by preventing the formation and proliferation of mutant cells. P53 activity is increased by DNA damage occurs caused by agents (such as radioation, UV light or drugs or oncogenes. Mdm2 protein can inhibit the p53 activation, but oncogenes can inhibit Mdm2 or activate p53. If DNA damage occurs, then p53 prevents the cells from replicating their DNA by arresting the cell cycle, so that the cells can repair the damage. Alternatively, p53 instructs the cells to undergo apoptosis by inducing bax gene expression, so that irregular cell growth, and cancer can be avoided. Cancer, including oral cancer, oftenthuolved cells with altered p53. Exogenous factors, such as tobacco and alcohol, presumably plays a role in triggering p53 mutations. Several techniques, such as immunohistochemistry and PCR can be used to investigation their etiology and development of oral cancer. The results hopefully be applied clinically in early detection, prevention and prediction of cancer. This paper discusses the role on p53 in preventing the occurrence and proliferation of mutated cells that lead to cancer, including oral cancer.

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

    Directory of Open Access Journals (Sweden)

    Zane Linda

    2012-12-01

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

  19. Driving p53 Response to Bax Activation Greatly Enhances Sensitivity to Taxol by Inducing Massive Apoptosis

    Directory of Open Access Journals (Sweden)

    Paola De Feudis

    2000-05-01

    Full Text Available The proapoptotic gene bax is one of the downstream effectors of p53. The p53 binding site in the bax promoter is less responsive to p53 than the one in the growth arrest mediating gene p21. We introduced the bax gene under the control of 13 copies of a strong p53 responsive element into two ovarian cancer cell lines. The clones expressing bax under the control of p53 obtained from the wild-type (wt p53-expressing cell line A2780 were much more sensitive (500- to 1000-fold to the anticancer agent taxol than the parent cell line, with a higher percentage of cells undergoing apoptosis after drug treatment that was clearly p53-dependent and bax-mediated. Xenografts established in nude mice from one selected clone (A2780/C3 were more responsive to taxol than the parental line and the apoptotic response of A2780/C3 tumors was also increased after treatment. Introduction of the same plasmid into the p53 null SKOV3 cell line did not alter the sensitivity to taxol or the induction of apoptosis. In conclusion, driving the p53 response (after taxol treatment by activating the bax gene rather than the p21 gene results in induction of massive apoptosis, in vitro and in vivo, and greatly enhances sensitivity to the drug.

  20. p53 transactivation and the impact of mutations, cofactors and small molecules using a simplified yeast-based screening system.

    Directory of Open Access Journals (Sweden)

    Virginia Andreotti

    Full Text Available BACKGROUND: The p53 tumor suppressor, which is altered in most cancers, is a sequence-specific transcription factor that is able to modulate the expression of many target genes and influence a variety of cellular pathways. Inactivation of the p53 pathway in cancer frequently occurs through the expression of mutant p53 protein. In tumors that retain wild type p53, the pathway can be altered by upstream modulators, particularly the p53 negative regulators MDM2 and MDM4. METHODOLOGY/PRINCIPAL FINDINGS: Given the many factors that might influence p53 function, including expression levels, mutations, cofactor proteins and small molecules, we expanded our previously described yeast-based system to provide the opportunity for efficient investigation of their individual and combined impacts in a miniaturized format. The system integrates i variable expression of p53 proteins under the finely tunable GAL1,10 promoter, ii single copy, chromosomally located p53-responsive and control luminescence reporters, iii enhanced chemical uptake using modified ABC-transporters, iv small-volume formats for treatment and dual-luciferase assays, and v opportunities to co-express p53 with other cofactor proteins. This robust system can distinguish different levels of expression of WT and mutant p53 as well as interactions with MDM2 or 53BP1. CONCLUSIONS/SIGNIFICANCE: We found that the small molecules Nutlin and RITA could both relieve the MDM2-dependent inhibition of WT p53 transactivation function, while only RITA could impact p53/53BP1 functional interactions. PRIMA-1 was ineffective in modifying the transactivation capacity of WT p53 and missense p53 mutations. This dual-luciferase assay can, therefore, provide a high-throughput assessment tool for investigating a matrix of factors that can influence the p53 network, including the effectiveness of newly developed small molecules, on WT and tumor-associated p53 mutants as well as interacting proteins.

  1. Regulation of p53 tetramerization and nuclear export by ARC

    OpenAIRE

    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.

    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 reloca...

  2. Autoantibody recognition mechanisms of p53 epitopes

    Science.gov (United States)

    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.

  3. P53 Gene Mutation as Biomarker of Radiation Induced Cell Injury and Genomic Instability

    International Nuclear Information System (INIS)

    Gene expression profiling and its mutation has become one of the most widely used approaches to identify genes and their functions in the context of identify and categorize genes to be used as radiation effect markers including cell and tissue sensitivities. Ionizing radiation produces genetic damage and changes in gene expression that may lead to cancer due to specific protein that controlling cell proliferation altered the function, its expression or both. P53 protein encoded by p53 gene plays an important role in protecting cell by inducing growth arrest and or cell suicide (apoptosis) after deoxyribonucleic acid (DNA) damage induced by mutagen such as ionizing radiation. The mutant and thereby dysfunctional of this gene was found in more than 50% of various human cancers, but it is as yet unclear how p53 mutations lead to neoplastic development. Wild-type p53 has been postulated to play a role in DNA repair, suggesting that expression of mutant forms of p53 might alter cellular resistance to the DNA damage caused by radiation. Moreover, p53 is thought to function as a cell cycle checkpoint after irradiation, also suggesting that mutant p53 might change the cellular proliferative response to radiation. P53 mutations affect the cellular response to DNA damage, either by increasing DNA repair processes or, possibly, by increasing cellular tolerance to DNA damage. The association of p53 mutations with increased radioresistance suggests that alterations in the p53 gene might lead to oncogenic transformation. Current attractive model of carcinogenesis also showed that p53 gene is the major target of radiation. The majority of p53 mutations found so far is single base pair changes ( point mutations), which result in amino acid substitutions or truncated forms of the p53 protein, and are widely distributed throughout the evolutionary conserved regions of the gene. Examination of p53 mutations in human cancer also shows an association between particular carcinogens and

  4. Molecular mechanisms of growth suppression by pharmacologically activated p53

    OpenAIRE

    Hedström, Elisabeth

    2009-01-01

    The tumor suppressor p53 is a transcription factor that is crucial for protecting cells from cancer development. The importance of p53 tumor suppression function is highlighted by the fact that the p53 pathway is inactivated in most, if not all cancers. Mutation of the p53 gene occurs in about 50% of all tumors, whereas in the tumors which retain wild-type p53, the function of p53 is abolished due to deregulation of the p53 pathway. Due to the potency of p53 in suppressing t...

  5. Interactions of chromatin context, binding site sequence content, and sequence evolution in stress-induced p53 occupancy and transactivation.

    Directory of Open Access Journals (Sweden)

    Dan Su

    2015-01-01

    Full Text Available Cellular stresses activate the tumor suppressor p53 protein leading to selective binding to DNA response elements (REs and gene transactivation from a large pool of potential p53 REs (p53REs. To elucidate how p53RE sequences and local chromatin context interact to affect p53 binding and gene transactivation, we mapped genome-wide binding localizations of p53 and H3K4me3 in untreated and doxorubicin (DXR-treated human lymphoblastoid cells. We examined the relationships among p53 occupancy, gene expression, H3K4me3, chromatin accessibility (DNase 1 hypersensitivity, DHS, ENCODE chromatin states, p53RE sequence, and evolutionary conservation. We observed that the inducible expression of p53-regulated genes was associated with the steady-state chromatin status of the cell. Most highly inducible p53-regulated genes were suppressed at baseline and marked by repressive histone modifications or displayed CTCF binding. Comparison of p53RE sequences residing in different chromatin contexts demonstrated that weaker p53REs resided in open promoters, while stronger p53REs were located within enhancers and repressed chromatin. p53 occupancy was strongly correlated with similarity of the target DNA sequences to the p53RE consensus, but surprisingly, inversely correlated with pre-existing nucleosome accessibility (DHS and evolutionary conservation at the p53RE. Occupancy by p53 of REs that overlapped transposable element (TE repeats was significantly higher (p<10-7 and correlated with stronger p53RE sequences (p<10-110 relative to nonTE-associated p53REs, particularly for MLT1H, LTR10B, and Mer61 TEs. However, binding at these elements was generally not associated with transactivation of adjacent genes. Occupied p53REs located in L2-like TEs were unique in displaying highly negative PhyloP scores (predicted fast-evolving and being associated with altered H3K4me3 and DHS levels. These results underscore the systematic interaction between chromatin status and p53

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

    Science.gov (United States)

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

    2016-01-01

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

  7. Development of Spontaneous Mammary Tumors in BALB/c p53 Heterozygous Mice : A Model for Li-Fraumeni Syndrome

    OpenAIRE

    Kuperwasser, Charlotte; Hurlbut, Gregory D; Kittrell, Frances S; Dickinson, Ellen S.; Laucirica, Rudy; Medina, Daniel; Naber, Stephen P.; Jerry, D. Joseph

    2000-01-01

    Breast cancer is the most frequent tumor type among women in the United States and in individuals with Li-Fraumeni syndrome. The p53 tumor suppressor gene is altered in a large proportion of both spontaneous breast malignancies and Li-Fraumeni breast cancers. This suggests that loss of p53 can accelerate breast tumorigenesis, yet p53-deficient mice rarely develop mammary tumors. To evaluate the effect of p53 loss on mammary tumor formation, the p53null allele was back-crossed onto the BALB/c ...

  8. Expression screening using a Medaka cDNA library identifies evolutionarily conserved regulators of the p53/Mdm2 pathway

    OpenAIRE

    P. Zhang; Kratz, A.S.; M. Salama; Elabd, S.; Heinrich, T; Wittbrodt, J.; Blattner, C.; G Davidson

    2015-01-01

    Background The p53 tumor suppressor protein is mainly regulated by alterations in the half-life of the protein, resulting in significant differences in p53 protein levels in cells. The major regulator of this process is Mdm2, which ubiquitinates p53 and targets it for proteasomal degradation. This process can be enhanced or reduced by proteins that associate with p53 or Mdm2 and several proteins have been identified with such an activity. Furthermore, additional ubiquitin ligases for p53 have...

  9. The p53 Isoform Δ133p53β Promotes Cancer Stem Cell Potential

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    Nikola Arsic

    2015-04-01

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

  10. Phosphorylation of Thr18 and Ser20 of p53 in Ad-p53 – induced apoptosis

    OpenAIRE

    Nakamizo, Akira; Amano, Toshiyuko; Zhang, Wei; Zhang, Xin-qiao; Ramdas, Latha; Liu, Ta-Jen; Bekele, B. Nebiyou; Shono, Tadahisa; Sasaki, Tomio; Benedict, William F.; Sawaya, Raymond; Lang, Frederick F.

    2008-01-01

    The p53 protein plays a critical role in inducing cell cycle arrest or apoptosis. Because p53 is inactivated in human gliomas, restoring p53 function is a major focus of glioma therapy. The most clinically tested strategy for replacing p53 has been adenoviral-mediated p53 gene therapy (Ad-p53). In addition to their therapeutic implications, investigations into Ad-p53 provide model systems for understanding p53’s ability to induce cell cycle arrest versus apoptosis, particularly because wild-t...

  11. Comparison of Nuclear Accumulation of p53 Protein with Mutations in the p53 Gene of Human Breast Cancer Tissues

    Institute of Scientific and Technical Information of China (English)

    王萱仪; 查小明; 武正炎; 范萍

    2001-01-01

    Objective The objective was to compare nuclear accumulation of p53 protein with mutations in the p53 gene on the tissues of human breast cancer. Methods Fifty-four invasive ductal carcinomas of breast were analyzed by the method of polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) silver stain and strep-avidin-biotin-peroxidase complex (SABC) immunohistochemistry. Results A statistically significant association between the presence of p53 gene mutation and nuclear accumulation of p53 protein was found (P<0.01). 22 tumors that demonstrated p53 gene mutations showed nuclear accumulation of p53 protein, while only 9 (28%) showed nuclear accumulation of p53 protein in 32 tumors without p53 gene mutations. Both p53 mutation protein and p53 gene mutations were prevalent in steroid and progesterone receptors negative tumors (P<0.05). A statistically significant association was found between the nuclear accumulation of p53 protein and lymph node invasion (P<0.05), and between p53 gene mutations and lymph node invasion (P<0.05). p53 abnormalities might be associated with an aggressive phenotype in breast cancer. Conclusion The immunohistochemical detection of nuclear p53 protein accumulation is highly associated with p53 gene mutations in breast cancer tissues, and that this method is useful for rapid screening of p53 abnormalities. However, in order to avoid false positive reaction, the p53 gene mutations should be determined in cases slightly positive for p53 nuclear protein.

  12. p53 Aggregates penetrate cells and induce the co-aggregation of intracellular p53.

    Directory of Open Access Journals (Sweden)

    Karolyn J Forget

    Full Text Available Prion diseases are unique pathologies in which the infectious particles are prions, a protein aggregate. The prion protein has many particular features, such as spontaneous aggregation, conformation transmission to other native PrP proteins and transmission from an individual to another. Protein aggregation is now frequently associated to many human diseases, for example Alzheimer's disease, Parkinson's disease or type 2 diabetes. A few proteins associated to these conformational diseases are part of a new category of proteins, called prionoids: proteins that share some, but not all, of the characteristics associated with prions. The p53 protein, a transcription factor that plays a major role in cancer, has recently been suggested to be a possible prionoid. The protein has been shown to accumulate in multiple cancer cell types, and its aggregation has also been reproduced in vitro by many independent groups. These observations suggest a role for p53 aggregates in cancer development. This study aims to test the «prion-like» features of p53. Our results show in vitro aggregation of the full length and N-terminally truncated protein (p53C, and penetration of these aggregates into cells. According to our findings, the aggregates enter cells using macropinocytosis, a non-specific pathway of entry. Lastly, we also show that once internalized by the cell, p53C aggregates can co-aggregate with endogenous p53 protein. Together, these findings suggest prion-like characteristics for p53 protein, based on the fact that p53 can spontaneously aggregate, these aggregates can penetrate cells and co-aggregate with cellular p53.

  13. Effects of Δ40p53, an isoform of p53 lacking the N-terminus, on transactivation capacity of the tumor suppressor protein p53

    OpenAIRE

    Hafsi, Hind; Santos-Silva, Daniela; Courtois-Cox, Stéphanie; Hainaut, Pierre

    2013-01-01

    Background The p53 protein is expressed as multiple isoforms that differ in their N- and C-terminus due to alternative splicing, promoter or codon initiation usage. Δ40p53 lacks the first 39 residues containing the main transcriptional activation domain, resulting from initiation of translation at AUG +40 in fully spliced p53 mRNA or in a specific variant mRNA retaining intron 2. Overexpression of Δ40p53 antagonizes wild-type p53 in vitro. However, animal models of Δ40p53 in mouse or Zebrafis...

  14. Effect of p53 on mitochondrial morphology, import, and assembly in skeletal muscle

    OpenAIRE

    Saleem, Ayesha; Iqbal, Sobia; Zhang, Yuan; Hood, David A.

    2014-01-01

    The purpose of this study was to investigate whether p53 regulates mitochondrial function via changes in mitochondrial protein import, complex IV (COX) assembly, or the expression of key proteins involved in mitochondrial dynamics and degradation. Mitochondria from p53 KO mice displayed ultra-structural alterations and were more punctate in appearance. This was accompanied by protein-specific alterations in fission, fusion, and mitophagy-related proteins. However, matrix-destined protein impo...

  15. INGN 201: Ad-p53, Ad5CMV-p53, adenoviral p53, p53 gene therapy--introgen, RPR/INGN 201.

    Science.gov (United States)

    2007-01-01

    Introgen and its wholly owned European subsidiary Gendux AB are developing an adenoviral p53 gene therapy as a treatment for cancer in the US and Europe, respectively. Phase III trials in patients with head and neck cancer are ongoing, and a number of clinical trials in other cancer indications have been completed. INGN 201 is being reviewed by the EMEA for approval in Li-Fraumeni syndrome (LFS) under the provisions of exceptional circumstance; the therapy is available on a compassionate use basis to eligible LFS cancer patients under a protocol authorised by the US FDA. The p53 tumour suppressor gene is deleted or mutated in many tumour cells and is one of the most frequently mutated genes in human tumours. The p53 protein is one of the most intricate elements in the apoptotic signalling cascade, and a mutation in the gene encoding it is believed to result in a decreased ability of a cell to apoptose. Thus replacing this gene via adenovirally-mediated p53 gene therapy is hoped to result in increased apoptosis where it is administered.INGN 201 is available for licensing, although Introgen favours retaining partial or full rights to the therapy in the US. Introgen entered into a license agreement with The University of Texas System and MD Anderson Cancer Center in 1994. The technologies licenced include p53 and fus1 (INGN 401). The collaboration has yielded exclusive patent and licensing rights to numerous technologies. Introgen entered into a collaboration with Rhône-Poulenc Rorer Pharmaceuticals (now sanofi-aventis) to develop therapeutics based on p53 inhibition in October 1994. However, in June 2001 this relationship was restructured and Introgen assumed responsibility for the worldwide development of all p53 products including INGN 201, and acquired all marketing and commercialisation rights with respect to those products. Introgen initiated two phase III trials in head and neck cancer (in June 2000 and May 2001) at about 80 sites in the US, Canada and Europe

  16. P53 and the defenses against genome instability caused by transposons and repetitive elements.

    Science.gov (United States)

    Levine, Arnold J; Ting, David T; Greenbaum, Benjamin D

    2016-06-01

    The recent publication by Wylie et al. is reviewed, demonstrating that the p53 protein regulates the movement of transposons. While this work presents genetic evidence for a piRNA-mediated p53 interaction with transposons in Drosophila and zebrafish, it is herein placed in the context of a decade or so of additional work that demonstrated a role for p53 in regulating transposons and other repetitive elements. The line of thought in those studies began with the observation that transposons damage DNA and p53 regulates DNA damage. The presence of transposon movement can increase the rate of evolution in the germ line and alter genes involved in signal transduction pathways. Transposition can also play an important role in cancers where the p53 gene function is often mutated. This is particularly interesting as recent work has shown that de-repression of repetitive elements in cancer has important consequences for the immune system and tumor microenvironment. PMID:27172878

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

    Science.gov (United States)

    Romano, Rose-Anne; Sinha, Satrajit

    2014-04-01

    The p53 family (p53, p63 and p73) is intimately linked with an overwhelming number of cellular processes during normal physiological as well as pathological conditions including cancer. The fact that these proteins are expressed in myriad isoforms, each with unique biochemical properties and distinct effects on tumorigenesis, complicates their study. A case in point is Squamous Cell Carcinoma (SCC) where p53 is often mutated and the ΔNp63 isoform is overexpressed. Given that p53 and p63 can hetero-dimerize, bind to quite similar DNA elements and share common co-factors, any alterations in their individual expression levels, activity and/or mutation can severely disrupt the family equilibrium. The burgeoning genomics data sets and new additions to the experimental toolbox are offering crucial insights into the complex role of the p53 family in SCC, but more mechanistic studies are needed. PMID:24690037

  18. cDNA sequencing improves the detection of P53 missense mutations in colorectal cancer

    International Nuclear Information System (INIS)

    Recently published data showed discrepancies beteween P53 cDNA and DNA sequencing in glioblastomas. We hypothesised that similar discrepancies may be observed in other human cancers. To this end, we analyzed 23 colorectal cancers for P53 mutations and gene expression using both DNA and cDNA sequencing, real-time PCR and immunohistochemistry. We found P53 gene mutations in 16 cases (15 missense and 1 nonsense). Two of the 15 cases with missense mutations showed alterations based only on cDNA, and not DNA sequencing. Moreover, in 6 of the 15 cases with a cDNA mutation those mutations were difficult to detect in the DNA sequencing, so the results of DNA analysis alone could be misinterpreted if the cDNA sequencing results had not also been available. In all those 15 cases, we observed a higher ratio of the mutated to the wild type template by cDNA analysis, but not by the DNA analysis. Interestingly, a similar overexpression of P53 mRNA was present in samples with and without P53 mutations. In terms of colorectal cancer, those discrepancies might be explained under three conditions: 1, overexpression of mutated P53 mRNA in cancer cells as compared with normal cells; 2, a higher content of cells without P53 mutation (normal cells and cells showing K-RAS and/or APC but not P53 mutation) in samples presenting P53 mutation; 3, heterozygous or hemizygous mutations of P53 gene. Additionally, for heterozygous mutations unknown mechanism(s) causing selective overproduction of mutated allele should also be considered. Our data offer new clues for studying discrepancy in P53 cDNA and DNA sequencing analysis

  19. Absence of p53 in Clara cells favours multinucleation and loss of cell cycle arrest

    Directory of Open Access Journals (Sweden)

    Clarke Alan R

    2002-11-01

    Full Text Available Abstract Background The p53 oncosuppressor protein is a critical mediator of the response to injury in mammalian cells and is mutationally inactivated in the majority of lung malignancies. In this analysis, the effects of p53-deficiency were investigated in short-term primary cultures of murine bronchiolar Clara cells. Clara cells, isolated from gene-targeted p53-deficient mice, were compared to cells derived from wild type littermates. Results p53 null cultures displayed abnormal morphology; specifically, a high incidence of multinucleation, which increased with time in culture. Multinucleated cells were proficient in S phase DNA synthesis, as determined by BrdU incorporation. However, multinucleation did not reflect altered rates of S phase synthesis, which were similar between wild type and p53-/- cultures. Nucleation defects in p53-/- Clara cells associated with increased centrosome number, as determined by confocal microscopy of pericentrin-stained cultures, and may highlight a novel role of p53 in preserving genomic integrity in lung epithelial cells. Effects of p53-deficiency were also studied following exposure to DNA damage. A p53-dependent reduction in the BrdU index was observed in Clara cells following ionizing radiation. The reduction in BrdU index in wild type cells displayed serum-dependency, and occurred only in the absence of serum. Taken together, these findings demonstrate that in murine primary Clara cell culture, cell cycle arrest is a p53-mediated response to DNA damage, and that extracellular factors, such as serum, influence this response. Conclusion These findings highlight functions of wild type p53 protein in bipolar spindle formation, centrosome regulation, and growth control in bronchiolar Clara cells.

  20. Role of p53 in Cell Death and Human Cancers

    OpenAIRE

    Toshinori Ozaki; Akira Nakagawara

    2011-01-01

    p53 is a nuclear transcription factor with a pro-apoptotic function. Since over 50% of human cancers carry loss of function mutations in p53 gene, p53 has been considered to be one of the classical type tumor suppressors. Mutant p53 acts as the dominant-negative inhibitor toward wild-type p53. Indeed, mutant p53 has an oncogenic potential. In some cases, malignant cancer cells bearing p53 mutations display a chemo-resistant phenotype. In response to a variety of cellular stresses such as DNA ...

  1. P53 FUSION PROTEIN EXPRESSION IN PROKARYOTE AND PREPARATION OF MONOCLONAL ANTIBODY TO P53

    Institute of Scientific and Technical Information of China (English)

    Liu Caiyun; Shou Chengchao; Sun Sulian; ZhangLei; Zeng Li

    1998-01-01

    Objective: Conventional immunohistochemistry (IHC) is available to assess P53 mutations, and expensive imported anti-P53 monoclonal antibody has been used in China, it is necessary to study a new monoclonal antibody.Methods: The P53 DNA fragment enconding N-terminal 180 amiao acide was obtained by PCR and was cloned into PGEX-2T plasmid expressing glutathione S-transferase (GST). The P53-GST fusion protein expressed by JM109was used for immunizing BALB/C mice. We have raised one hybridoma strain secreting McAb to human P53(named M126). Results: The IHC analysis of 52paraffin-embedded sections from human breast cancer with M126 and PAB1801 (Zymed Co.) has showed that the positive immunoreactions were 25 cases (48%) and 22cases (42.3%) respectively. The staining of M126 was stronger and preferable to PAB1801. Conclusion: M126can be instead of PAB1801 for studying immunohistochemical analysis on P53 Protein.

  2. Distribution of p53 expression in tissue from 774 Danish ovarian tumour patients and its prognostic significance in ovarian carcinomas

    DEFF Research Database (Denmark)

    Hogdall, E.V.S.; Christensen, L.; Frederiksen, K.;

    2008-01-01

    The clinical roles played by normal and altered p53 in cancer are under intensive investigation, but larger studies describing the pattern as well as the prognostic value are still needed. The aim of this study was, using tissue array (TA), to examine the overexpression of p53 protein in 774...... epithelial ovarian tumour tissues from Danish women and to evaluate whether p53 tissue expression levels correlate with clinicopathological parameters and prognosis. The distribution of p53 expression levels at different stages of disease, in different histological subtypes, and the prognostic value of p53...... tissue expression were examined. Overall, p53 was expressed in 24/189 (13%) low malignant potential ovarian tumours (LMP) and in 278/585 (48%) ovarian cancers (OC). No significant difference in frequency of p53 tissue expression in LMP tissue was noted with increasing tumour stage (p=0.98). By contrast...

  3. Interfacial behavior of wild type and mutant p53 proteins

    Czech Academy of Sciences Publication Activity Database

    Paleček, Emil; Havran, Luděk; Dorčák, Vlastimil; Billová, Sabina; Brázdová, Marie; Masařík, Michal; Vacek, Jan; Fojta, Miroslav

    Ein Gedi, 2005. s. 15. [2nd International Workshop on Mutant p53: The p53 Regulatory Network and Functional Consequences of p53 Mutations. 17.11.2005-21.11.2005, Ein Gedi] R&D Projects: GA AV ČR(CZ) IAA500040513 Institutional research plan: CEZ:AV0Z50040507 Keywords : electrochemistry of protein p53 * protein p53 mutants Subject RIV: BO - Biophysics

  4. Controlling the Mdm2-Mdmx-p53 Circuit

    OpenAIRE

    Waning, David L.; Lehman, Jason A.; Batuello, Christopher N.; Mayo, Lindsey D.

    2010-01-01

    The p53 tumor suppressor is a key protein in maintaining the integrity of the genome by inducing either cell cycle arrest or apoptosis following cellular stress signals. Two human family members, Mdm2 and Mdmx, are primarily responsible for inactivating p53 transcription and targeting p53 protein for ubiquitin-mediated degradation. In response to genotoxic stress, post-translational modifications to p53, Mdm2 and Mdmx stabilize and activate p53. The role that phosphorylation of these molecule...

  5. Ferroptosis: A missing puzzle piece in the p53 blueprint?

    Science.gov (United States)

    Wang, Shang-Jui; Ou, Yang; Jiang, Le; Gu, Wei

    2016-05-01

    Recent evidence indicates that canonical functions of p53 (i.e., apoptosis and growth arrest) are dispensable for p53-mediated tumor suppression. We have uncovered a novel function of p53 that contributes to tumor suppression through regulation of cystine metabolism, reactive oxygen species responses, and ferroptosis. The p53-mediated ferroptotic response via SLC7A11 denotes an extra layer of defense against tumorigenesis in conjunction with other p53 functions. PMID:27314071

  6. Highly metastatic hepatocellular carcinomas induced in male F344 rats treated with N-nitrosomorpholine in combination with other hepatocarcinogens show a high incidence of p53 gene mutations along with altered mRNA expression of tumor-related genes.

    Science.gov (United States)

    Masui, T; Nakanishi, H; Inada, K; Imai, T; Mizoguchi, Y; Yada, H; Futakuchi, M; Shirai, T; Tatematsu, M

    1997-01-15

    The carcinogenic and metastatic processes are thought to consist of a sequence of steps, and animal models featuring highly metastatic lesions are clearly necessary to allow analysis of the whole process of transformation from preneoplastic changes to high grade metastatic tumors, and to access effectiveness of therapeutic treatments of advanced cancers in vivo. The purpose of the present study was to establish a model and to screen for reported genetic alterations in induced lesions. In the present study, it was confirmed that lung metastasis of hepatocellular carcinomas (HCCs) induced in male F344 rats by N-nitrosomorpholine (NNM), given in the drinking water at a dose of 120 ppm for 24 weeks, was significantly enhanced by additional carcinogenic pretreatments and that a single i.p. injection of 100 mg/kg body weight N-diethylnitrosamine (DEN) alone was sufficient for that purpose. Molecular biological analyses of the induced lesions revealed point mutations in the p53 gene in 60.9% of HCCs, and elevated expression of mRNAs for p53, c-myc, c-fos, TGF-alpha, TGF-beta1, alpha-fetoprotein, GST-P, and GGT, and decreased mRNA expression of EGF and EGFR in HCCs when compared to controls. No obvious association of gene alterations with metastatic potential of primary tumors was found except for an increase in the incidence of p53 mutations. Since the process of metastasis is thought to be sequential and selective, further comparative analysis of metastatic and primary lesions should clarify the mechanisms involved in the multi-step process of metastasis. PMID:9029167

  7. Loss of CDKN2A expression is a frequent event in primary invasive melanoma and correlates with sensitivity to the CDK4/6 inhibitor PD0332991 in melanoma cell lines.

    Science.gov (United States)

    Young, Richard J; Waldeck, Kelly; Martin, Claire; Foo, Jung H; Cameron, Donald P; Kirby, Laura; Do, Hongdo; Mitchell, Catherine; Cullinane, Carleen; Liu, Wendy; Fox, Stephen B; Dutton-Regester, Ken; Hayward, Nicholas K; Jene, Nicholas; Dobrovic, Alexander; Pearson, Richard B; Christensen, James G; Randolph, Sophia; McArthur, Grant A; Sheppard, Karen E

    2014-07-01

    We have investigated the potential for the p16-cyclin D-CDK4/6-retinoblastoma protein pathway to be exploited as a therapeutic target in melanoma. In a cohort of 143 patients with primary invasive melanoma, we used fluorescence in situ hybridization to detect gene copy number variations (CNVs) in CDK4, CCND1, and CDKN2A and immunohistochemistry to determine protein expression. CNVs were common in melanoma, with gain of CDK4 or CCND1 in 37 and 18% of cases, respectively, and hemizygous or homozygous loss of CDKN2A in 56%. Three-quarters of all patients demonstrated a CNV in at least one of the three genes. The combination of CCND1 gain with either a gain of CDK4 and/or loss of CDKN2A was associated with poorer melanoma-specific survival. In 47 melanoma cell lines homozygous loss, methylation or mutation of CDKN2A gene or loss of protein (p16(INK) (4A) ) predicted sensitivity to the CDK4/6 inhibitor PD0332991, while RB1 loss predicted resistance. PMID:24495407

  8. The p53 target Wig-1 regulates p53 mRNA stability through an AU-rich element

    DEFF Research Database (Denmark)

    Vilborg, Anna; Glahder, Jacob-Andreas Harald; Wilhelm, Margareta T;

    2009-01-01

    The p53 target gene Wig-1 encodes a double-stranded-RNA-binding zinc finger protein. We show here that Wig-1 binds to p53 mRNA and stabilizes it through an AU-rich element (ARE) in the 3' UTR of the p53 mRNA. This effect is mirrored by enhanced p53 protein levels in both unstressed cells and cells...... exposed to p53-activating stress agents. Thus, the p53 target Wig-1 is a previously undescribed ARE-regulating protein that acts as a positive feedback regulator of p53, with implications both for the steady-state levels of p53 and for the p53 stress response. Our data reveal a previously undescribed link...... between the tumor suppressor p53 and posttranscriptional gene regulation via AREs in mRNA....

  9. Cancer-derived p53 mutants suppress p53-target gene expression—potential mechanism for gain of function of mutant p53

    OpenAIRE

    Vikhanskaya, Faina; Lee, Ming Kei; Mazzoletti, Marco; Broggini, Massimo; Sabapathy, Kanaga

    2007-01-01

    Tumour-derived p53 mutants are thought to have acquired ‘gain-of-function’ properties that contribute to oncogenicity. We have tested the hypothesis that p53 mutants suppress p53-target gene expression, leading to enhanced cellular growth. Silencing of mutant p53 expression in several human cell lines was found to lead to the upregulation of wild-type p53-target genes such as p21, gadd45, PERP and PTEN. The expression of these genes was also suppressed in H1299-based isogenic cell lines expre...

  10. Retention of wild-type p53 in tumors from p53 heterozygous mice: reduction of p53 dosage can promote cancer formation.

    OpenAIRE

    Venkatachalam, S; Shi, Y P; Jones, S N; Vogel, H.; Bradley, A.; Pinkel, D; Donehower, L A

    1998-01-01

    Tumor suppressor genes are generally viewed as being recessive at the cellular level, so that mutation or loss of both tumor suppressor alleles is a prerequisite for tumor formation. The tumor suppressor gene, p53, is mutated in approximately 50% of human sporadic cancers and in an inherited cancer predisposition (Li-Fraumeni syndrome). We have analyzed the status of the wild-type p53 allele in tumors taken from p53-deficient heterozygous (p53+/-) mice. These mice inherit a single null p53 al...

  11. Effects of p53 mutants derived from lung carcinomas on the p53-responsive element (p53RE) of the MDM2 gene

    OpenAIRE

    Gorgoulis, V. G.; Zacharatos, P. V.; Manolis, E.; Ikonomopoulos, J. A.; Damalas, A.; Lamprinopoulos, C.; Rassidakis, G Z; Zoumpourlis, Vassilis; Kotsinas, A.; Rassidakis, A. N.; Halazonetis, T. D.; KITTAS, C.

    2008-01-01

    The present study represents a continuation of previous works in which we observed that lung carcinomas co-expressing MDM2 protein and p53 mutants (mt p53) exhibited more aggressive behaviour. In the above studies, we suggested a 'gain of function' mechanism of mt p53 proteins based on the fact that the MDM2 gene possesses a p53-responsive element (MDM2-p53RE). In this study, to prove our hypothesis, we selected 12 cases from a series of 51 bronchogenic carcinomas. In these 12 cases, we exami...

  12. Small-molecule modulators of p53 family signaling and antitumor effects in p53-deficient human colon tumor xenografts

    OpenAIRE

    Wang, Wenge; Kim, Seok-Hyun; El-Deiry, Wafik S

    2006-01-01

    p53 deficiency is common in almost all human tumors and contributes to an aggressive chemo- or radiotherapy-resistant phenotype, therefore providing a target for drug development. Molecular targeting to restore wild-type p53 activity has been attempted in drug development and has led to the identification of CP-31398, PRIMA1, and the Nutlins. However, strategies targeting p53-activated transcriptional responses or p53 family member expression in p53-deficient tumors have yet to be explored. H...

  13. Soft-shell clam (Mya arenaria) p53: A structural and functional comparison to human p53

    OpenAIRE

    Holbrook, Lauren A.C.; Butler, Rondi A.; Cashon, Robert E.; Van Beneden, Rebecca J.

    2008-01-01

    The tumor suppressor p53 regulates genes involved in progression through the cell cycle, DNA repair, senescence or apoptosis in response to cell stress. Dysregulation of p53 can result in uncontrolled cellular proliferation. Invertebrate homologues to human p53 (Hsp53) have been identified, including a putative p53 gene (Map53) from the soft-shell clam (Mya arenaria). Predicted sequences for human and clam p53 proteins exhibit conservation in key domains. In light of this similarity, and the ...

  14. Disruptive cell cycle regulation involving epigenetic downregulation of Cdkn2a (p16Ink4a) in early-stage liver tumor-promotion facilitating liver cell regeneration in rats

    International Nuclear Information System (INIS)

    Cell cycle aberration was immunohistochemically examined in relation to preneoplastic liver cell foci expressing glutathione S-transferase placental form (GST-P) at early stages of tumor-promotion in rats with thioacetamide (TAA), a hepatocarcinogen facilitating liver cell regeneration. Immunoexpression of p16Ink4a following exposure to other hepatocarcinogens/promoters and its DNA methylation status were also analyzed during early and late tumor-promotion stages. GST-P+ liver cell foci increased cell proliferation and decreased apoptosis when compared with surrounding liver cells. In concordance with GST-P+ foci, checkpoint proteins at G1/S (p21Cip1, p27Kip1 and p16Ink4a) and G2/M (phospho-checkpoint kinase 1, Cdc25c and phospho-Wee1) were either up- or downregulated. Cellular distribution within GST-P+ foci was either increased or decreased with proteins related to G2-M phase or DNA damage (topoisomerase IIα, phospho-histone H2AX, phospho-histone H3 and Cdc2). In particular, p16Ink4a typically downregulated in GST-P+ foci and regenerative nodules at early tumor-promotion stage with hepatocarcinogens facilitating liver cell regeneration and in neoplastic lesions at late tumor-promotion stage with hepatocarcinogens/promoters irrespective of regenerating potential. Hypermethylation at exon 2 of Cdkn2a was detected at both early- and late-stages. Thus, diverse disruptive expression of G1/S and G2/M proteins, which allows for clonal selection of GST-P+ foci, results in the acquisition of multiple aberrant phenotypes to disrupt checkpoint function. Moreover, increased DNA-damage responses within GST-P+ foci may be the signature of genetic alterations. Intraexonic hypermethylation may be responsible for p16Ink4a-downregulation, which facilitates cell cycle progression in early preneoplastic lesions produced by repeated cell regeneration and late-stage neoplastic lesions irrespective of the carcinogenic mechanism.

  15. Potential role of p53 mutation in chemical hepatocarcinogenesis of rats

    Institute of Scientific and Technical Information of China (English)

    Wei-Guo Deng; Yan Fu; Yu-Lin Li; Toshihiro Sugiyama

    2004-01-01

    AIM: Inactivation of p53 gene is one of the most frequent genetic alterations in carcinogenesis. The mutation status of p53 gene was analyzed, in order to understand the effect of p53 mutation on chemical hepatocarcinogenesis of rats.METHODS: During hepatocarcinogenesis of rats induced by 3′-methyl-4- dimethylaminoazobenzene (3′-Me-DAB),prehepatocarcinoma and hepatocarcinoma foci were collected by laser capture microdissection (LCMl), and quantitatively analyzed for levels of p53 mRNA by LightCyclerTM real-time RT-PCR and for mutations in p53 gene exons 5-8 by direct sequencing.RESULTS: Samples consisting of 44 precancerous foci and 24 cancerous foci were collected by LCMl. A quantitative analysis of p53 mRNA showed that p53 mRNA peaked at an early stage (week 6) in the prehepatocarcinoma lesion, more than ten times that of adjacent normal tissue, and gradually decreased from week 6 to week 24. The expression of p53 mRNA in adjacent normal tissue was significantly lower than that in prehepatocarcinoma. Similar to prehepatocarcinoma,p53 mRNA in cancer was markedly higher than that in adjacent normal tissue at week 12, and was closer to normal at week 24. Direct p53 gene sequencing showed that 35.3% (24/68) (9 precancer, 15 cancer) LCM samples exhibited point mutations, 20.5% of prehepatocarcinoma LCM samples presented missense mutations at exon 6/7 or/and 8, and was markedly lower than 62.5% of hepatocarcinoma ones (P<0.01). Mlutation of p53 gene formed the mutant hot spots at 5 codons. Positive immunostaining for p53 protein could be seen in prehepatocarcinoma and hepatocarcinoma foci at 24 weeks.CONCLUSION: p53 gene mutation is present in initial chemical hepatocarcinogenesis, and the mutation of p53 gene induced by 3′-Me-DAB is an important factor of hepatocarcinogenesis.

  16. Iron Metabolism Regulates p53 Signaling through Direct Heme-p53 Interaction and Modulation of p53 Localization, Stability, and Function

    Directory of Open Access Journals (Sweden)

    Jia Shen

    2014-04-01

    Full Text Available Iron excess is closely associated with tumorigenesis in multiple types of human cancers, with underlying mechanisms yet unclear. Recently, iron deprivation has emerged as a major strategy for chemotherapy, but it exerts tumor suppression only on select human malignancies. Here, we report that the tumor suppressor protein p53 is downregulated during iron excess. Strikingly, the iron polyporphyrin heme binds to p53 protein, interferes with p53-DNA interactions, and triggers both nuclear export and cytosolic degradation of p53. Moreover, in a tumorigenicity assay, iron deprivation suppressed wild-type p53-dependent tumor growth, suggesting that upregulation of wild-type p53 signaling underlies the selective efficacy of iron deprivation. Our findings thus identify a direct link between iron/heme homeostasis and the regulation of p53 signaling, which not only provides mechanistic insights into iron-excess-associated tumorigenesis but may also help predict and improve outcomes in iron-deprivation-based chemotherapy.

  17. Expression of Androgen Receptor Is Negatively Regulated By p53

    Directory of Open Access Journals (Sweden)

    Fatouma Alimirah

    2007-12-01

    Full Text Available Increased expression of androgen receptor (AR in prostate cancer (PC is associated with transition to androgen independence. Because the progression of PC to advanced stages is often associated with the loss of p53 function, we tested whether the p53 could regulate the expression of AR gene. Here we report that p53 negatively regulates the expression of AR in prostate epithelial cells (PrECs. We found that in LNCaP human prostate cancer cells that express the wild-type p53 and AR and in human normal PrECs, the activation of p53 by genotoxic stress or by inhibition of p53 nuclear export downregulated the expression of AR. Furthermore, forced expression of p53 in LNCaP cells decreased the expression of AR. Conversely, knockdown of p53 expression in LNCaP cells increased the AR expression. Consistent with the negative regulation of AR expression by p53, the p53-null HCT116 cells expressed higher levels of AR compared with the isogenic HCT116 cells that express the wildtype p53. Moreover, we noted that in etoposide treated LNCaP cells p53 bound to the promoter region of the AR gene, which contains a potential p53 DNA-binding consensus sequence, in chromatin immunoprecipitation assays. Together, our observations provide support for the idea that the loss of p53 function in prostate cancer cells contributes to increased expression of AR.

  18. Analysis of p53 mutants for transcriptional activity.

    OpenAIRE

    Raycroft, L.; Schmidt, J. R.; Yoas, K; Hao, M M; Lozano, G.

    1991-01-01

    The wild-type p53 protein functions to suppress transformation, but numerous mutant p53 proteins are transformation competent. To examine the role of p53 as a transcription factor, we made fusion proteins containing human or mouse p53 sequences fused to the DNA binding domain of a known transcription factor, GAL4. Human and mouse wild-type p53/GAL4 specifically transactivated expression of a chloramphenicol acetyltransferase reporter in HeLa, CHO, and NIH 3T3 cells. Several mutant p53 protein...

  19. 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

    OpenAIRE

    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

    2010-01-01

    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 sat...

  20. Activation and activities of the p53 tumour suppressor protein

    OpenAIRE

    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 pat...

  1. 乳癌病人血清p53抗体与组织p53的比较%The relationship between serum p53Abs and tissue p53

    Institute of Scientific and Technical Information of China (English)

    郭美琴; 郭铁柱; 丰美芳

    2002-01-01

    目的比较乳癌病人血清p53抗体和组织p53表达之间的关系.方法 68例乳癌病人血清p53抗体用酶联免疫法(ELISA)检测,组织p53蛋白用免疫组织化学法检测.结果 68例乳癌病人血清p53抗体阳性19例,阳性率28%,组织p53阳性27例,阳性率40%,组织p53阳性同时血清p53抗体阳性者14例,组织p53阳性而血清p53抗体阴性者13例,组织p53阴性但血清p53抗体阳性者5例.结论组织和血清之间具有密切相关性,但非完全一致,p53抗体的检测更是一个预测乳癌复发或高危险性的指标.

  2. Expression of TP53 isoforms p53β or p53γ enhances chemosensitivity in TP53(null) cell lines.

    Science.gov (United States)

    Silden, Elisabeth; Hjelle, Sigrun M; Wergeland, Line; Sulen, André; Andresen, Vibeke; Bourdon, Jean-Christophe; Micklem, David R; McCormack, Emmet; Gjertsen, Bjørn Tore

    2013-01-01

    The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53(null) background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate with increased response to camptothecin and doxorubicin chemotherapy. Decreased DNA synthesis and clonogenicity in p53β and p53γ congenic H1299 was accompanied by increased p21((CIP1/WAF1)), Bax and Mdm2 proteins. Chemotherapy induced p53 isoform degradation, most prominent for p53γ. The proteasome inhibitor bortezomib substantially increased basal p53γ protein level, while the level of p53β protein was unaffected. Treatment with dicoumarol, a putative blocker of the proteasome-related NAD(P)H quinone oxidoreductase NQO1, effectively attenuated basal p53γ protein level in spite of bortezomib treatment. Although in vitro proliferation and clonogenicity assays indicated a weak suppressive effect by p53β and p53γ expression, studies of in vivo subcutaneous H1299 tumor growth demonstrated a significantly increased growth by expression of either p53 isoforms. This study suggests that p53β and p53γ share functionality in chemosensitizing and tumor growth enhancement but comprise distinct regulation at the protein level. PMID:23409163

  3. Expression of TP53 isoforms p53β or p53γ enhances chemosensitivity in TP53(null cell lines.

    Directory of Open Access Journals (Sweden)

    Elisabeth Silden

    Full Text Available The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53(null background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate with increased response to camptothecin and doxorubicin chemotherapy. Decreased DNA synthesis and clonogenicity in p53β and p53γ congenic H1299 was accompanied by increased p21((CIP1/WAF1, Bax and Mdm2 proteins. Chemotherapy induced p53 isoform degradation, most prominent for p53γ. The proteasome inhibitor bortezomib substantially increased basal p53γ protein level, while the level of p53β protein was unaffected. Treatment with dicoumarol, a putative blocker of the proteasome-related NAD(PH quinone oxidoreductase NQO1, effectively attenuated basal p53γ protein level in spite of bortezomib treatment. Although in vitro proliferation and clonogenicity assays indicated a weak suppressive effect by p53β and p53γ expression, studies of in vivo subcutaneous H1299 tumor growth demonstrated a significantly increased growth by expression of either p53 isoforms. This study suggests that p53β and p53γ share functionality in chemosensitizing and tumor growth enhancement but comprise distinct regulation at the protein level.

  4. Changing the p53 master regulatory network: ELEMENTary, my dear Mr Watson.

    Science.gov (United States)

    Menendez, D; Inga, A; Jordan, J J; Resnick, M A

    2007-04-01

    The p53 master regulatory network provides for the stress-responsive direct control of a vast number of genes in humans that can be grouped into several biological categories including cell-cycle control, apoptosis and DNA repair. Similar to other sequence-specific master regulators, there is a matrix of key components, which provide for variation within the p53 master regulatory network that include p53 itself, target response element sequences (REs) that provide for p53 regulation of target genes, chromatin, accessory proteins and transcription machinery. Changes in any of these can impact the expression of individual genes, groups of genes and the eventual biological responses. The many REs represent the core of the master regulatory network. Since defects or altered expression of p53 are associated with over 50% of all cancers and greater than 90% of p53 mutations are in the sequence-specific DNA-binding domain, it is important to understand the relationship between wild-type or mutant p53 proteins and the target response elements. In the words of the legendary detective Sherlock Holmes, it is 'Elementary, my dear Mr. Watson'. PMID:17401428

  5. Orphan Nuclear Receptor PNR/NR2E3 Stimulates p53 Functions by Enhancing p53 Acetylation

    OpenAIRE

    WEN, ZHI; Pyeon, Dohun; Wang, Yidan; Lambert, Paul; Xu, Wei; Ahlquist, Paul

    2012-01-01

    Since inactivation of tumor suppressor p53 functions is one of the most common features of human cancer cells, restoring p53 expression and activity is an important focus in cancer therapy. Here we report identification of photoreceptor-specific nuclear receptor (PNR)/NR2E3 as a positive regulator of p53 in a high-throughput genetic screen. In HeLa cells, PNR stimulated p53-responsive promoters in a p53-dependent fashion and induced apoptosis in several cell types. PNR also increased p53 prot...

  6. Expression of TP53 Isoforms p53β or p53γ Enhances Chemosensitivity in TP53null Cell Lines

    OpenAIRE

    Elisabeth Silden; Hjelle, Sigrun M; Line Wergeland; André Sulen; Vibeke Andresen; Jean-Christophe Bourdon; Micklem, David R; Emmet McCormack; Bjørn Tore Gjertsen

    2013-01-01

    The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53(null) background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate wi...

  7. Adenovirus Ad-p53AIP1-mediated gene therapy and its regulation of p53-MDM2 interactions

    OpenAIRE

    Jiang, Yunbo; Chen, Huihua; JIA, HAIQUAN; XU, YUANJI; Liu, Gang; Wang, Yan; Yang, Xiaohe; Yinglin LU

    2010-01-01

    We generated replication-defective adenovirus Ad-p53AIP1 and studied its anti-tumor efficacy both in vitro and in vivo. We demonstrated that Ad-p53AIP1 infection elicited high levels of p53AIP1 expression in cancer cells. We also found that Ad-p53AIP1 expression induced marked apoptosis and cell cycle arrest in HepG2 cells. Moreover, Ad-p53AIP1 infection significantly inhibited the tumorigenesis of 4T1 mouse mammary cancer cells in vivo. In particular, we discovered that p53AIP1 overexpressio...

  8. Quaternary structure of the specific p53–DNA complex reveals the mechanism of p53 mutant dominance

    OpenAIRE

    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 s...

  9. Expression of TP53 Isoforms p53β or p53γ Enhances Chemosensitivity in TP53null Cell Lines

    OpenAIRE

    Silden, Elisabeth; Hjelle, Sigrun M; Wergeland, Line; Sulen, André; Andresen, Vibeke; Bourdon, Jean-Christophe; Micklem, David R.; McCormack, Emmet; Gjertsen, Bjørn Tore

    2013-01-01

    The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53null background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate with...

  10. Restriction of human herpesvirus 6B replication by p53

    DEFF Research Database (Denmark)

    Øster, Bodil; Kofod-Olsen, Emil; Bundgaard, Bettina;

    2008-01-01

    Human herpesvirus 6B (HHV-6B) induces significant accumulation of p53 in both the nucleus and cytoplasm during infection. Activation of p53 by DNA damage is known to induce either growth arrest or apoptosis; nevertheless, HHV-6B-infected cells are arrested in their cell cycle independently of p53......, and only a minor fraction of the infected cells undergoes apoptosis. Using pifithrin-alpha, a p53 inhibitor, and p53-null cells, this study showed that infected epithelial cells accumulated viral transcripts and proteins to a significantly higher degree in the absence of active p53. Moreover, HHV-6B......-induced cytopathic effects were greatly enhanced in the absence of p53. This suggests that, in epithelial cells, some of the functions of p53 leading to cell-cycle arrest and apoptosis are restrained by HHV-6B infection, whereas other cellular defences, causing inhibition of virus transcription, are partially...

  11. Implication of K-ras and p53 in colorectal cancer carcinogenesis in Tunisian population cohort.

    Science.gov (United States)

    Ines, Chaar; Donia, Ounissi; Rahma, Boughriba; Ben Ammar, Azza; Sameh, Amara; Khalfallah, Taher; Abdelmajid, Ben Hmida; Sabeh, Mzabi; Saadia, Bouraoui

    2014-07-01

    According to the multistep route of genetic alterations in the colorectal adenoma-carcinoma sequence, the complex K-ras/p53 mutation is one of the first alterations to occur and represent an important genetic event in colorectal cancer (CRC). An evaluation of the mutation spectra in K-ras and p53 gene was effected in 167 Tunisian patients with sporadic CRC to determine whether our populations have similar pattern of genetic alteration as in Maghrebin's population. Mutation patterns of codon 12-13 of K-ras and exon 5-8 of p53 were analyzed by immunohistochemistry and PCR-SSCP and confirmed by sequencing. Mutations in the K-ras gene were detected in 31.13 % and affect the women more than the men (p = 0.008). Immunostaining showed that expression of p21 ras was correlated with the advanced age (p = 0.004), whereas loss of signal was associated with mucinous histotype (p = 0.003). Kaplan-Meier survival curve found that patients with the K-ras mutation had a shorter survival compared with patients without mutation (p = 0.005). Alteration in p53 was seen in 17.4 % of patients and affects three hot spot codons such as 175, 245, and 248. Overexpression of p53 was seen in 34.1 % and correlated with tumor node metastasis (TNM) advanced stage (p = 0.037) and mucinous histotype (p = 0.001). A high concordance between p53 expression and alteration (p<0.005) was shown. Concomitant mutations in K-ras and p53 gene were detected in only 4 % of tumors. K-ras and p53 undergo separate pathways in colorectal tumorogenesis. Interestingly, mutations in the K-ras gene might be considered a valuable prognostic factor correlated to poor outcome. p53 gene alterations were rather low in our set, and methylation pattern of p53 is required to elucidate the molecular basis of this protein in CRC. PMID:24763823

  12. Mutations in p53, p53 protein overexpression and breast cancer survival

    Czech Academy of Sciences Publication Activity Database

    Rössner ml., Pavel; Gammon, M. D.; Zhang, Y.J.; Terry, M. B.; Hibshoosh, H.; Memeo, L.; Mansukhani, M.; Long, CH.M.; Gabrowski, G.; Agrawal, M.; Kalra, T.S.; Teitelbaum, S. L.; Neugut, A. I.; Santella, R. M.

    2009-01-01

    Roč. 13, č. 9B (2009), s. 3847-3857. ISSN 1582-1838 Institutional research plan: CEZ:AV0Z50390512 Keywords : Breast cancer * p53 mutations * Survival Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 5.228, year: 2009

  13. Modulation of p53's transcriptional function by small molecules

    OpenAIRE

    Nikulenkov, Fedor

    2011-01-01

    p53 tumour suppressor is a transcriptional factor which induces apoptosis or growth arrest in response to stress thus eliminating damaged cells. p53 function is frequently abrogated in tumours either via inactivation mutations in the TP53 gene or by elevated activity of p53 negative regulators HDM2 and HDMX. Therefore application of small molecules that reactivate p53 function is a promising strategy for anti-cancer therapy. In addition, small molecules can serve as valuable research tool to ...

  14. Targeting p53 and its domains for cancer gene therapy

    OpenAIRE

    Karina Julia Matissek

    2014-01-01

    The tumor suppressor p53 is one of the most frequently mutated proteins in human cancer and has been extensively targeted for cancer therapy. This resulted in wild type p53 gene therapeutic approval for the treatment of head and neck cancer in China. p53 mainly functions as a transcription factor and stimulates a variety of genes involved in the intrinsic and extrinsic apoptotic pathway by binding to p53 responsive elements as a t...

  15. Prima-1 induces apoptosis in bladder cancer cell lines by activating p53

    Directory of Open Access Journals (Sweden)

    Camila B. Piantino

    2013-01-01

    Full Text Available OBJECTIVES: Bladder cancer represents 3% of all carcinomas in the Brazilian population and ranks second in incidence among urological tumors, after prostate cancer. The loss of p53 function is the main genetic alteration related to the development of high-grade muscle-invasive disease. Prima-1 is a small molecule that restores tumor suppressor function to mutant p53 and induces cancer cell death in various cancer types. Our aim was to investigate the ability of Prima-1 to induce apoptosis after DNA damage in bladder cancer cell lines. METHOD: The therapeutic effect of Prima-1 was studied in two bladder cancer cell lines: T24, which is characterized by a p53 mutation, and RT4, which is the wild-type for the p53 gene. Morphological features of apoptosis induced by p53, including mitochondrial membrane potential changes and the expression of thirteen genes involved in apoptosis, were assessed by microscopic observation and quantitative real-time PCR (qRT-PCR. RESULTS: Prima-1 was able to reactivate p53 function in the T24 (p53 mt bladder cancer cell line and promote apoptosis via the induction of Bax and Puma expression, activation of the caspase cascade and disruption of the mitochondrial membrane in a BAK-independent manner. CONCLUSION: Prima-1 is able to restore the transcriptional activity of p53. Experimental studies in vivo may be conducted to test this molecule as a new therapeutic agent for urothelial carcinomas of the bladder, which characteristically harbor p53 mutations.

  16. p53 specific (auto)immunity in mice

    NARCIS (Netherlands)

    Lauwen, Marjolein Monique

    2008-01-01

    Self-tolerance to p53 is a major potential limitation for the activation of the endogenous T-cell repertoire. So far, p53 specific CD8+ and CD4+ T-cell immunity has been described in cancer patients and healthy individuals. However, the restrictions of tolerance on the recruitment of p53 specific T

  17. Mutual interactions between P53 and growth factors in cancer

    NARCIS (Netherlands)

    Asschert, JGW; Vellenga, E; De Jong, S; De Vries, EGE

    1998-01-01

    The function of p53 armour suppressor protein is determined by various intrinsic properties of the protein. The effect of p53 DNA-binding, and platein-protein interactions are determined by the conformation of the protein. Thus p53 fulfils its role in cell cycle control and the onset of apoptotic ce

  18. Identification of p53-target genes in Danio rerio

    Science.gov (United States)

    Mandriani, Barbara; Castellana, Stefano; Rinaldi, Carmela; Manzoni, Marta; Venuto, Santina; Rodriguez-Aznar, Eva; Galceran, Juan; Nieto, M. Angela; Borsani, Giuseppe; Monti, Eugenio; Mazza, Tommaso; Merla, Giuseppe; Micale, Lucia

    2016-01-01

    To orchestrate the genomic response to cellular stress signals, p53 recognizes and binds to DNA containing specific and well-characterized p53-responsive elements (REs). Differences in RE sequences can strongly affect the p53 transactivation capacity and occur even between closely related species. Therefore, the identification and characterization of a species-specific p53 Binding sistes (BS) consensus sequence and of the associated target genes may help to provide new insights into the evolution of the p53 regulatory networks across different species. Although p53 functions were studied in a wide range of species, little is known about the p53-mediated transcriptional signature in Danio rerio. Here, we designed and biochemically validated a computational approach to identify novel p53 target genes in Danio rerio genome. Screening all the Danio rerio genome by pattern-matching-based analysis, we found p53 RE-like patterns proximal to 979 annotated Danio rerio genes. Prioritization analysis identified a subset of 134 candidate pattern-related genes, 31 of which have been investigated in further biochemical assays. Our study identified runx1, axin1, traf4a, hspa8, col4a5, necab2, and dnajc9 genes as novel direct p53 targets and 12 additional p53-controlled genes in Danio rerio genome. The proposed combinatorial approach resulted to be highly sensitive and robust for identifying new p53 target genes also in additional animal species. PMID:27581768

  19. Role of p53 in Cell Death and Human Cancers

    International Nuclear Information System (INIS)

    p53 is a nuclear transcription factor with a pro-apoptotic function. Since over 50% of human cancers carry loss of function mutations in p53 gene, p53 has been considered to be one of the classical type tumor suppressors. Mutant p53 acts as the dominant-negative inhibitor toward wild-type p53. Indeed, mutant p53 has an oncogenic potential. In some cases, malignant cancer cells bearing p53 mutations display a chemo-resistant phenotype. In response to a variety of cellular stresses such as DNA damage, p53 is induced to accumulate in cell nucleus to exert its pro-apoptotic function. Activated p53 promotes cell cycle arrest to allow DNA repair and/or apoptosis to prevent the propagation of cells with serious DNA damage through the transactivation of its target genes implicated in the induction of cell cycle arrest and/or apoptosis. Thus, the DNA-binding activity of p53 is tightly linked to its tumor suppressive function. In the present review article, we describe the regulatory mechanisms of p53 and also p53-mediated therapeutic strategies to cure malignant cancers

  20. Overexpression of DRAM enhances p53-dependent apoptosis

    International Nuclear Information System (INIS)

    Tumor suppressor p53-dependent apoptosis is thought to be one of the most important tumor-suppressive mechanisms in human tumorigenesis. Till date, “super p53” mutants exhibiting more potent ability to induce apoptosis than wild-type p53 have been reported. These super p53s may provide a clue for development of novel therapeutic targets. However, the major mechanism underlying the super p53-dependent apoptosis remains unclear. To identify critical gene(s) in this mechanism, we performed a comprehensive and comparative expression analysis in p53-null Saos-2 cells with conditional expression of wild-type p53 and S121F, which was previously reported as a super p53 mutant. We identified damage-regulated autophagy modulator (DRAM) as one of the genes that were more upregulated by S121F than wild-type p53. Although knockdown of DRAM was not sufficient for reducing the ability of S121F to induce apoptosis, DRAM overexpression enhanced the ability in a wild-type p53-dependent manner. Here, we show that DRAM is an important gene for the enhancement of p53-dependent apoptosis. Additional analysis of the mechanism of super p53-dependent apoptosis may lead to the identification of novel drug targets for cancer therapy

  1. Identification of p53-target genes in Danio rerio.

    Science.gov (United States)

    Mandriani, Barbara; Castellana, Stefano; Rinaldi, Carmela; Manzoni, Marta; Venuto, Santina; Rodriguez-Aznar, Eva; Galceran, Juan; Nieto, M Angela; Borsani, Giuseppe; Monti, Eugenio; Mazza, Tommaso; Merla, Giuseppe; Micale, Lucia

    2016-01-01

    To orchestrate the genomic response to cellular stress signals, p53 recognizes and binds to DNA containing specific and well-characterized p53-responsive elements (REs). Differences in RE sequences can strongly affect the p53 transactivation capacity and occur even between closely related species. Therefore, the identification and characterization of a species-specific p53 Binding sistes (BS) consensus sequence and of the associated target genes may help to provide new insights into the evolution of the p53 regulatory networks across different species. Although p53 functions were studied in a wide range of species, little is known about the p53-mediated transcriptional signature in Danio rerio. Here, we designed and biochemically validated a computational approach to identify novel p53 target genes in Danio rerio genome. Screening all the Danio rerio genome by pattern-matching-based analysis, we found p53 RE-like patterns proximal to 979 annotated Danio rerio genes. Prioritization analysis identified a subset of 134 candidate pattern-related genes, 31 of which have been investigated in further biochemical assays. Our study identified runx1, axin1, traf4a, hspa8, col4a5, necab2, and dnajc9 genes as novel direct p53 targets and 12 additional p53-controlled genes in Danio rerio genome. The proposed combinatorial approach resulted to be highly sensitive and robust for identifying new p53 target genes also in additional animal species. PMID:27581768

  2. Inhibitor or promoter? The performance of polysaccharides from Ganoderma lucidum on human tumor cells with different p53 statuses.

    Science.gov (United States)

    Zhang, Jue; Chen, Jun-ming; Wang, Xiao-xia; Xia, Yong-mei; Cui, Steve W; Li, Jian; Ding, Zhong-yang

    2016-04-01

    Polysaccharides from Ganoderma lucidum (GLPs) have been taken as effective supplements by both healthy people and cancer patients for many years. However, this short survey indicates that instead of inhibiting cancer cell growth, both submerge-cultured intracellular GLP and fruiting body GLP can stimulate the growth of human carcinoma cell lines lacking functional p53, such as HCT-116 p53(-/-), Saos-2, H1299, HL-60, MDA-MB-157. Conversely, the two GLPs inhibit all other assayed cells with functional p53. These results could be an alert since mutational inactivation of the tumor suppressor protein p53 is the most frequent genetic alteration found in human tumors. PMID:26999513

  3. Mutations of the adenomatous polyposis coli and p53 genes in a child with Turcot's syndrome.

    Science.gov (United States)

    Barel, D; Cohen, I J; Mor, C; Stern, S; Shapiro, R; Shomrat, R; Galanti, Y; Legum, C; Zaizov, R; Avigad, S

    1998-10-23

    Turcot's syndrome is a rare heritable complex that is characterized by an association between a primary neuroepithelial tumor of the central nervous system and multiple colonic polyps. The aim of this study was to analyze genetic alterations in a case of Turcot's syndrome in a 10.5-year-old boy in whom a colorectal tumor developed 3.5 years following astrocytoma. An APC germline non-sense mutation at codon 1284 leading to a truncated protein was identified, as was a somatic p53 mutation in the colorectal carcinoma in exon 7, codon 244. The latter was not identified in the primary astrocytoma. However, immunohistochemistry revealed high p53 protein expression in both tumors, suggesting an additional p53 mutation in the primary astrocytic tumor. The diverse p53 mutations observed in this unique syndrome in two different sites and stages of the disease may shed light on the multistep progression of the malignant events. PMID:10397462

  4. The prognostic value of p53 mutation in pediatric marrow hypoplasia

    Directory of Open Access Journals (Sweden)

    Sharaf Alzahraa EA

    2011-06-01

    Full Text Available Abstract Background The tumor suppressor gene p53 is involved in the control of cell proliferation, particularly in stressed cells. p 53 gene mutations are the most frequent genetic event found in human cancers. Fanconi Anemia (FA is the most common representative of inherited bone marrow failure syndromes (IBMFS with a leukemic propensity. P 53 DNA alteration has not been studied before in Egyptian children with FA. Patients and methods we investigated p53 mutation in the bone marrow and peripheral blood of forty children, FA (n = 10, acquired aplastic anemia (AAA (n = 10, and immune thrombocytopenia (ITP as a control (n = 20, using real-time PCR by TaqMan probe assay Results Mutation of p53 gene was demonstrated in the BM of 90% (9/10 of children with FA, compared to 10% (1/10 in AAA (p Conclusion mutation of p53 gene in hypoplastic marrow especially FA may represent an early indicator of significant DNA genetic alteration with cancer propensity.

  5. CD8 T-cell responses against cyclin B1 in breast cancer patients with tumors overexpressing p53

    DEFF Research Database (Denmark)

    Sørensen, Rikke Baek; Andersen, Rikke Sick; Svane, Inge Marie;

    2009-01-01

    CD8 T-cell response against at least one of the peptides; strongest reactivity was detected against the CB9L2 peptide. Because the level of cyclin B1 has been shown to be influenced by the level of p53, which in turn is elevated in cancer cells because of point mutation, we analyzed the level of p53...... protein in biopsies from the patients by immune histochemistry. Combined data showed that anti-cyclin B1 reactivity was predominantly detected in patients with tumors characterized by elevated expression of p53. Interestingly, no reactivity was detected against six peptides derived from the p53 protein....... CONCLUSIONS: Our data support the notion of cyclin B1 as a prominent target for immunologic recognition in cancer patients harboring p53-mutated cancer cells. Because mutation of p53 is one of the most frequent genetic alterations in human cancers, this suggests that immunotherapy based on targeting of cyclin...

  6. Resistance of mitochondrial p53 to dominant inhibition

    Directory of Open Access Journals (Sweden)

    Mestres Pedro

    2008-06-01

    Full Text Available Abstract Background Mutation of a tumor suppressor allele leaves the second as backup. Not necessarily so with p53. This homo-tetrameric transcription factor can become contaminated with mutant p53 through hetero-tetramerization. In addition, it can be out-competed by the binding to p53 DNA recognition motifs of transactivation-incompetent isoforms (ΔN and ΔTA-isoforms of the p53/p63/p73 family of proteins. Countermeasures against such dominant-negative or dominant-inhibitory action might include the evolutionary gain of novel, transactivation-independent tumor suppressor functions by the wild-type monomer. Results Here we have studied, mostly in human HCT116 colon adenocarcinoma cells with an intact p53 pathway, the effects of dominant-inhibitory p53 mutants and of Δex2/3p73, a tumor-associated ΔTA-competitor of wild-type p53, on the nuclear transactivation-dependent and extra-nuclear transactivation-independent functions of wild-type p53. We report that mutant p53 and Δex2/3p73, expressed from a single gene copy per cell, interfere with the stress-induced expression of p53-responsive genes but leave the extra-nuclear apoptosis by mitochondrial p53 largely unaffected, although both wild-type and mutant p53 associate with the mitochondria. In accord with these observations, we present evidence that in contrast to nuclear p53 the vast majority of mitochondrial p53, be it wild-type or mutant, is consisting of monomeric protein. Conclusion The extra-nuclear p53-dependent apoptosis may constitute a fail-safe mechanism against dominant inhibition.

  7. Cellular adaptation to hypoxia and p53 transcription regulation

    Institute of Scientific and Technical Information of China (English)

    Yang ZHAO; Xue-qun CHEN; Ji-zeng DU

    2009-01-01

    Tumor suppressor p53 is the most frequently mutated gene in human tumors. Meanwhile, under stress conditions, p53 also acts as a transcription factor, regulating the expression of a series of target genes to maintain the integrity of genome. The target genes of p53 can be classified into genes regulating cell cycle arrest, genes involved in apoptosis, and genes inhibiting angiogenesis. p53 protein contains a transactivation domain, a sequence-specific DNA binding domain, a tetramerization domain, a non-specific DNA binding domain that recognizes damaged DNA, and a later identified proline-rich domain. Under stress, p53 proteins accumulate and are activated through two mechanisms. One, involving ataxia telangiectasia-mutated protein (ATM), is that the interaction between p53 and its down-regulation factor murine double minute 2 (MDM2) decreases, leading to p53 phosphorylation on Ser15, as determined by the post-translational mechanism; the other holds that p53 increases and is activated through the binding of ribosomal protein L26 (RPL26) or nucleolin to p53 mRNA 5' untranslated region (UTR), regulating p53 translation. Under hypoxia, p53 decreases transactivation and increases transrepression. The mutations outside the DNA binding domain of p53 also contribute to tumor progress, so further studies on p53 should also be focused on this direction. The subterranean blind mole rat Spalax in Israel is a good model for hypoxia-adaptation. The p53 of Spalax mutated in residue 172 and residue 207 from arginine to lysine, conferring it the ability to survive hypoxic conditions. This model indicates that p53 acts as a master gene of diversity formation during evolution.

  8. p53CP, a putative p53 competing protein that specifically binds to the consensus p53 DNA binding sites: A third member of the p53 family?

    OpenAIRE

    Bian, Junhui; Sun, Yi

    1997-01-01

    p53 tumor suppressor protein negatively regulates cell growth, mainly through the transactivation of its downstream target genes. As a sequence-specific DNA binding transcription factor, p53 specifically binds to a 20-bp consensus motif 5′-PuPuPuC(A/T) (T/A)GPyPyPyPuPuPuC(A/T)(T/A)GPyPyPy-3′. We have now identified, partially purified, and characterized an additional ≈40-kDa nuclear protein, p53CP (p53 competing protein), that specifically binds to the consensus p53 binding sites found in sev...

  9. Targeting p53 Null Neuroblastomas through RLIP76**

    OpenAIRE

    Singhal, Jyotsana; Yadav, Sushma; Nagaprashantha, Lokesh Dalasanur; Vatsyayan, Rit; SINGHAL, SHARAD S.; Awasthi, Sanjay

    2011-01-01

    The search for p53-independent mechanism of cancer cell killing is highly relevant to pediatric neuroblastomas, where successful therapy is limited by its transformation into p53 mutant and a highly drug-resistant neoplasm. Our studies on the drug-resistant p53 mutant as compared with drug-resistant p53 wild-type neuroblastoma revealed a novel mechanism for resistance to apoptosis: a direct role of p53 in regulating the cellular concentration of pro-apoptotic alkenals by functioning as a spec...

  10. [Bcl-2 inhibits p53-induced apoptosis after genotoxic damage by inhibitors of nuclear import of p53].

    Science.gov (United States)

    Beham, A; Schumacher, G; McDonnell, T J; Marin, M C; Jauch, K W

    1998-01-01

    The tumor suppressor gene p53 in overexpressed in 50% of colorectal carcinomas and is an interesting target for gene therapeutic approaches. Furthermore the protooncogen bcl-2 is known to inhibit p53 induced apoptosis and is expressed in some colorectal carcinomas. In this study mechanism of bcl-2 cell death inhibition after p53 induction were evaluated. The human colon carcinoma cell line RKO posses wild-type p53 and also expresses bcl-2 protein. RKO cells were treated with liposomal bcl-2 antisense oligonucleotides (AS), control oligonucleotides (CO) and empty liposomes (EL) resulting in decreased bcl-2 expression. After induction of p53 with gamma-irradiation p53 protein expression was induced in AS, CO and EL pretreated cells. Microscopy and immunoblotting was used to characterize subcellular localization of p53 protein. Further p53 subcellular localisation was examined after p53 transfer of wt p53 cDNA in three bcl-2 expressing cell lines. Most of the p53 protein remained localized in the cytosol and apoptosis was decreased in bcl-2 expressing cells assessed by flow cytometric analysis (Ao). Our data suggests that bcl-2 is able to modulate transmembrane trafficking of p53. This resulted in inhibition of cell death implicating that bcl-2 function is involved in regulation of transmembrane gradients. PMID:14518224

  11. Tumor suppressor p53 meets microRNAs

    Institute of Scientific and Technical Information of China (English)

    Zhaohui Feng; Cen Zhang; Rui Wu; Wenwei Hu

    2011-01-01

    Tumor suppressor p53 plays a central role in tumor prevention. As a transcription factor, p53 mainly exerts its function through transcription regulation of its target genes to initiate various cellular responses. To maintain its proper function, p53 is tightly regulated by a wide variety of regulators in cells. Thus, p53, its regulators and regulated genes form a complex p53 network which is composed of hundreds of genes and their products. microRNAs (miRNAs) are a class of endogenously expressed, small non-coding RNA molecules which play a key role in regulation of gene expression at the post-transcriptional level. Recent studies have demonstrated that miRNAs interact with p53 and its network at multiple levels. p53 regulates the transcription expression and the maturation of a group of miRNAs. On the other hand, miRNAs can regulate the activity and function of p53 through direct repression of p53 or its regulators in cells. These findings have demonstrated that miRNAs are important components in the p53 network, and also added another layer of complexity to the p53 network.

  12. A novel p53-binding domain in CUL7.

    Science.gov (United States)

    Kasper, Jocelyn S; Arai, Takehiro; DeCaprio, James A

    2006-09-15

    CUL7 is a member of the cullin RING ligase family and forms an SCF-like complex with SKP1 and FBXW8. CUL7 is required for normal mouse embryonic development and cellular proliferation, and is highly homologous to PARC, a p53-associated, parkin-like cytoplasmic protein. We determined that CUL7, in a manner similar to PARC, can bind directly to p53 but does not affect p53 expression. We identified a discrete, co-linear domain in CUL7 that is conserved in PARC and HERC2, and is necessary and sufficient for p53-binding. The presence of p53 stabilized expression of this domain and we demonstrate that this p53-binding domain of CUL7 contributes to the cytoplasmic localization of CUL7. The results support the model that p53 plays a role in regulation of CUL7 activity. PMID:16875676

  13. The p53-MDM2 network: from oscillations to apoptosis

    Indian Academy of Sciences (India)

    Indrani Bose; Bhaswar Ghosh

    2007-08-01

    The p53 protein is well-known for its tumour suppressor function. The p53-MDM2 negative feedback loop constitutes the core module of a network of regulatory interactions activated under cellular stress. In normal cells, the level of p53 proteins is kept low by MDM2, i.e. MDM2 negatively regulates the activity of p53. In the case of DNA damage, the p53-mediated pathways are activated leading to cell cycle arrest and repair of the DNA. If repair is not possible due to excessive damage, the p53-mediated apoptotic pathway is activated bringing about cell death. In this paper, we give an overview of our studies on the p53-MDM2 module and the associated pathways from a systems biology perspective. We discuss a number of key predictions, related to some specific aspects of cell cycle arrest and cell death, which could be tested in experiments.

  14. Epigenetic changes in the CDKN2A locus are associated with differential expression of P16INK4A and P14ARF in HPV-positive oropharyngeal squamous cell carcinoma

    International Nuclear Information System (INIS)

    Human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) is recognized as a distinct disease entity associated with improved survival. DNA hypermethylation profiles differ significantly by HPV status suggesting that a specific subset of methylated CpG loci could give mechanistic insight into HPV-driven OPSCC. We analyzed genome-wide DNA methylation of primary tumor samples and adjacent normal mucosa from 46 OPSCC patients undergoing treatment at Montefiore Medical Center, Bronx, NY using the Illumina HumanMethylation27 beadchip. For each matched tissue set, we measured differentially methylated CpG loci using a change in methylation level (M value). From these analyses, we identified a 22 CpG loci panel for HPV+ OPSCC that included four CDKN2A loci downstream of the p16(INK4A) and p14(ARF) transcription start sites. This panel was significantly associated with overall HPV detection (P < 0.05; ROC area under the curve = 0.96, 95% CI: 0.91–1.0) similar to the subset of four CDKN2A-specific CpG loci (0.90, 95% CI: 0.82–0.99) with equivalence to the full 22 CpG panel. DNA hypermethylation correlated with a significant increase in alternative open reading frame (ARF) expression in HPV+ OPSCC primary tumors, but not to the other transcript variant encoded by the CDKN2A locus. Overall, this study provides evidence of epigenetic changes to the downstream region of the CDKN2A locus in HPV+ oropharyngeal cancer that are associated with changes in expression of the coded protein products

  15. Failure of CDKN2A/B (INK4A/B–ARF)-mediated tumor suppression and resistance to targeted therapy in acute lymphoblastic leukemia induced by BCR-ABL

    OpenAIRE

    Mullighan, Charles G.; Williams, Richard T.; Downing, James R.; Sherr, Charles J.

    2008-01-01

    Deletions of the CDKN2A/B tumor suppressor locus and of the IKAROS and PAX5 genes that promote B-lineage development occur frequently in lymphoid, but not myeloid leukemias initiated by the BCR-ABL tyrosine kinase. Why is this the case, and how do these genetic lesions contribute to an aggressive disease that fails to durably respond to targeted kinase inhibitors?

  16. Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents

    NARCIS (Netherlands)

    Michaelis, M.; Rothweiler, F.; Agha, B.; Barth, S.; Voges, Y.; Loeschmann, N.; von Deimling, A.; Breitling, R.; Doerr, H. Wilhelm; Roedel, F.; Speidel, D.; Cinatl, J.; Cinatl Jr., J.; Stephanou, A.

    2012-01-01

    Adaptation of wild-type p53 expressing UKF-NB-3 cancer cells to the murine double minute 2 inhibitor nutlin-3 causes de novo p53 mutations at high frequency (13/20) and multi-drug resistance. Here, we show that the same cells respond very differently when adapted to RITA, a drug that, like nutlin-3,

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

    OpenAIRE

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

    2014-01-01

    p53 functions as a tumor suppressor by transcriptionally regulating the expression of genes involved in controlling cell proliferation or apoptosis. p53 and its isoform Δ133p53/Δ113p53 form a negative regulation loop in that p53 activates the expression of Δ133p53/Δ113p53 while Δ133p53/Δ113p53 specifically antagonizes p53 apoptotic activity. This pathway is especially important to safeguard the process of embryogenesis because sudden activation of p53 by DNA damage signals or developmental st...

  18. Loss of p53-regulatory protein IFI16 induces NBS1 leading to activation of p53-mediated checkpoint by phosphorylation of p53 SER37.

    Science.gov (United States)

    Tawara, Hideyuki; Fujiuchi, Nobuko; Sironi, Juan; Martin, Sarah; Aglipay, Jason; Ouchi, Mutsuko; Taga, Makoto; Chen, Phang-Lang; Ouchi, Toru

    2008-01-01

    Our previous results that IFI16 is involved in p53 transcription activity under conditions of ionizing radiation (IR), and that the protein is frequently lost in human breast cancer cell lines and breast adenocarcinoma tissues suggesting that IFI16 plays a crucial role in controlling cell growth. Here, we show that loss of IFI16 by RNA interference in cell culture causes elevated phosphorylation of p53 Ser37 and accumulated NBS1 (nibrin) and p21WAF1, leading to growth retardation. Consistent with these observations, doxycyclin-induced NBS1 caused accumulation of p21WAF1 and increased phosphorylation of p53 Ser37, leading to cell cycle arrest in G1 phase. Wortmannin treatment was found to decrease p53 Ser37 phosphorylation in NBS-induced cells. These results suggest that loss of IFI16 activates p53 checkpoint through NBS1-DNA-PKcs pathway. PMID:17981542

  19. p53 facilitates pRb cleavage in IL-3-deprived cells: novel pro-apoptotic activity of p53.

    OpenAIRE

    Gottlieb, E; Oren, M.

    1998-01-01

    In the interleukin-3 (IL-3)-dependent lymphoid cell line DA-1, functional p53 is required for efficient apoptosis in response to IL-3 withdrawal. Activation of p53 in these cells, by either DNA damage or p53 overexpression, results in a vital growth arrest in the presence of IL-3 and in accelerated apoptosis in its absence. Thus, IL-3 can control the choice between p53-dependent cell-cycle arrest and apoptosis. Here we report that the cross-talk between p53 and IL-3 involves joint control of ...

  20. Oncogenomic Approaches in Exploring Gain of Function of Mutant p53

    Science.gov (United States)

    Donzelli, Sara; Biagioni, Francesca; Fausti, Francesca; Strano, Sabrina; Fontemaggi, Giulia; Blandino, Giovanni

    2008-01-01

    Cancer is caused by the spatial and temporal accumulation of alterations in the genome of a given cell. This leads to the deregulation of key signalling pathways that play a pivotal role in the control of cell proliferation and cell fate. The p53 tumor suppressor gene is the most frequent target in genetic alterations in human cancers. The primary selective advantage of such mutations is the elimination of cellular wild type p53 activity. In addition, many evidences in vitro and in vivo have demonstrated that at least certain mutant forms of p53 may possess a gain of function, whereby they contribute positively to cancer progression. The fine mapping and deciphering of specific cancer phenotypes is taking advantage of molecular-profiling studies based on genome-wide approaches. Currently, high-throughput methods such as array-based comparative genomic hybridization (CGH array), single nucleotide polymorphism array (SNP array), expression arrays and ChIP-on-chip arrays are available to study mutant p53-associated alterations in human cancers. Here we will mainly focus on the integration of the results raised through oncogenomic platforms that aim to shed light on the molecular mechanisms underlying mutant p53 gain of function activities and to provide useful information on the molecular stratification of tumor patients. PMID:19440517

  1. Rb and p53 Liver Functions Are Essential for Xenobiotic Metabolism and Tumor Suppression.

    Directory of Open Access Journals (Sweden)

    Sathidpak Nantasanti

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

  2. Genome wide expression profiling of p53 regulated miRNAs in neuroblastoma.

    Science.gov (United States)

    Rihani, Ali; Van Goethem, Alan; Ongenaert, Maté; De Brouwer, Sara; Volders, Pieter-Jan; Agarwal, Saurabh; De Preter, Katleen; Mestdagh, Pieter; Shohet, Jason; Speleman, Frank; Vandesompele, Jo; Van Maerken, Tom

    2015-01-01

    Restoration of the antitumor activity of p53 could offer a promising approach for the treatment of neuroblastoma. MicroRNAs (miRNAs) are important mediators of p53 activity, but their role in the p53 response has not yet been comprehensively addressed in neuroblastoma. Therefore, we set out to characterize alterations in miRNA expression that are induced by p53 activation in neuroblastoma cells. Genome-wide miRNA expression analysis showed that miR-34a-5p, miR-182-5p, miR-203a, miR-222-3p, and miR-432-5p are upregulated following nutlin-3 treatment in a p53 dependent manner. The function of miR-182-5p, miR-203a, miR-222-3p, and miR-432-5p was analyzed by ectopic overexpression of miRNA mimics. We observed that these p53-regulated miRNAs inhibit the proliferation of neuroblastoma cells to varying degrees, with the most profound growth inhibition recorded for miR-182-5p. Overexpression of miR-182-5p promoted apoptosis in some neuroblastoma cell lines and induced neuronal differentiation of NGP cells. Using Chromatin Immunoprecipitation-qPCR (ChIP-qPCR), we did not observe direct binding of p53 to MIR182, MIR203, MIR222, and MIR432 in neuroblastoma cells. Taken together, our findings yield new insights in the network of p53-regulated miRNAs in neuroblastoma. PMID:25762502

  3. Role of p53 isoforms and aggregations in cancer.

    Science.gov (United States)

    Kim, SeJin; An, Seong Soo A

    2016-06-01

    p53 is a master regulatory protein that is involved in diverse cellular metabolic processes such as apoptosis, DNA repair, and cell cycle arrest. The protective function of p53 (in its homotetrameric form) as a tumor suppressor is lost in more than 50% of human cancers.Despite considerable experimental evidence suggesting the presence of multiple p53 states, it has been difficult to correlate the status of p53 with cancer response to treatments and clinical outcomes, which suggest the importance of complex but essential p53 regulatory pathways.Recent studies have indicated that the expression pattern of p53 isoforms may play a crucial role in regulating normal and cancer cell fates in response to diverse stresses. The human TP53 gene encodes at least 12 p53 isoforms, which are produced in normal tissue through alternative initiation of translation, usage of alternative promoters, and alternative splicing. Furthermore, some researchers have suggested that the formation of mutant p53 aggregates may be associated with cancer pathogenesis due to loss-of function (LoF), dominant-negative (DN), and gain-of function (GoF) effects.As different isoforms or the aggregation state of p53 may influence tumorigenesis, this review aims to examine the correlation of p53 isoforms and aggregation with cancer. PMID:27368003

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

    International Nuclear Information System (INIS)

    Research highlights: → Mfn2 is a novel target gene of p53. → Mfn2 mRNA and protein levels can be up-regulated in a p53-dependent manner. → Mfn2 promoter activity can be elevated by the p53 protein. → 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.

  5. P53 family and cellular stress responses in cancer

    Directory of Open Access Journals (Sweden)

    Johanna ePflaum

    2014-10-01

    Full Text Available p53 is an important tumor suppressor gene, which is stimulated by cellular stress like ionizing radiation, hypoxia, carcinogens and oxidative stress. Upon activation p53 leads to cell cycle arrest and promotes DNA repair or induces apoptosis via several pathways. p63 and p73 are structural homologs of p53 that can act similarly to the protein but also hold functions distinct from p53. Today more than forty different isoforms of the p53 family members are known. They result from transcription via different promoters and alternative splicing. Some isoforms have carcinogenic properties and mediate resistance to chemotherapy. Therefore, expression patterns of the p53 family genes can offer prognostic information in several malignant tumors. Furthermore, the p53 family constitutes a potential target for cancer therapy. Small molecules (e.g. Nutlins, RITA, PRIMA-1, and MIRA-1 among others have been objects of intense research interest in recent years. They restore pro-apoptotic wild-type p53 function and were shown to break chemotherapeutic resistance. Due to p53 family interactions small molecules also influence p63 and p73 activity. Thus, the members of the p53 family are key players in the cellular stress response in cancer and are expected to grow in importance as therapeutic targets.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Weilin; Cheng, Xiaofei; Lu, Jianju; Wei, Jianfeng [Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, Key Lab of Organ Transplantation, Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China); Fu, Guanghou [Department of Urology, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou (China); Zhu, Feng; Jia, Changku; Zhou, Lin; Xie, Haiyang [Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, Key Lab of Organ Transplantation, Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China); Zheng, Shusen, E-mail: shusenzheng@zju.edu.cn [Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, Key Lab of Organ Transplantation, Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China)

    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.

  7. P53 family members modulate the expression of PRODH, but not PRODH2, via intronic p53 response elements.

    Directory of Open Access Journals (Sweden)

    Ivan Raimondi

    Full Text Available The tumor suppressor p53 was previously shown to markedly up-regulate the expression of the PRODH gene, encoding the proline dehydrogenase (PRODH enzyme, which catalyzes the first step in proline degradation. Also PRODH2, which degrades 4-hydroxy-L-proline, a product of protein (e.g. collagen catabolism, was recently described as a p53 target. Here, we confirmed p53-dependent induction of endogenous PRODH in response to genotoxic damage in cell lines of different histological origin. We established that over-expression of TAp73β or TAp63β is sufficient to induce PRODH expression in p53-null cells and that PRODH expression parallels the modulation of endogenous p73 by genotoxic drugs in several cell lines. The p53, p63, and p73-dependent transcriptional activation was linked to specific intronic response elements (REs, among those predicted by bioinformatics tools and experimentally validated by a yeast-based transactivation assay. p53 occupancy measurements were validated in HCT116 and MCF7 human cell lines. Conversely, PRODH2 was not responsive to p63 nor p73 and, at best, could be considered a weak p53 target. In fact, minimal levels of PRODH2 transcript induction by genotoxic stress was observed exclusively in one of four p53 wild-type cell lines tested. Consistently, all predicted p53 REs in PRODH2 were poor matches to the p53 RE consensus and showed very weak responsiveness, only to p53, in the functional assay. Taken together, our results highlight that PRODH, but not PRODH2, expression is under the control of p53 family members, specifically p53 and p73. This supports a deeper link between proteins of the p53-family and metabolic pathways, as PRODH modulates the balance of proline and glutamate levels and those of their derivative alpha-keto-glutarate (α-KG under normal and pathological (tumor conditions.

  8. A synthetic interaction screen identifies factors selectively required for proliferation and TERT transcription in p53-deficient human cancer cells.

    Directory of Open Access Journals (Sweden)

    Li Xie

    Full Text Available Numerous genetic and epigenetic alterations render cancer cells selectively dependent on specific genes and regulatory pathways, and represent potential vulnerabilities that can be therapeutically exploited. Here we describe an RNA interference (RNAi-based synthetic interaction screen to identify genes preferentially required for proliferation of p53-deficient (p53- human cancer cells. We find that compared to p53-competent (p53+ human cancer cell lines, diverse p53- human cancer cell lines are preferentially sensitive to loss of the transcription factor ETV1 and the DNA damage kinase ATR. In p53- cells, RNAi-mediated knockdown of ETV1 or ATR results in decreased expression of the telomerase catalytic subunit TERT leading to growth arrest, which can be reversed by ectopic TERT expression. Chromatin immunoprecipitation analysis reveals that ETV1 binds to a region downstream of the TERT transcriptional start-site in p53- but not p53+ cells. We find that the role of ATR is to phosphorylate and thereby stabilize ETV1. Our collective results identify a regulatory pathway involving ETV1, ATR, and TERT that is preferentially important for proliferation of diverse p53- cancer cells.

  9. Residues in the alternative reading frame tumor suppressor that influence its stability and p53-independent activities

    International Nuclear Information System (INIS)

    The Alternative Reading Frame (ARF) protein suppresses tumorigenesis through p53-dependent and p53-independent pathways. Most of ARF's anti-proliferative activity is conferred by sequences in its first exon. Previous work showed specific amino acid changes occurred in that region during primate evolution, so we programmed those changes into human p14ARF to assay their functional impact. Two human p14ARF residues (Ala14 and Thr31) were found to destabilize the protein while two others (Val24 and Ala41) promoted more efficient p53 stabilization and activation. Despite those effects, all modified p14ARF forms displayed robust p53-dependent anti-proliferative activity demonstrating there are no significant biological differences in p53-mediated growth suppression associated with simian versus human p14ARF residues. In contrast, p53-independent p14ARF function was considerably altered by several residue changes. Val24 was required for p53-independent growth suppression whereas multiple residues (Val24, Thr31, Ala41 and His60) enabled p14ARF to block or reverse the inherent chromosomal instability of p53-null MEFs. Together, these data pinpoint specific residues outside of established p14ARF functional domains that influence its expression and signaling activities. Most intriguingly, this work reveals a novel and direct role for p14ARF in the p53-independent maintenance of genomic stability.

  10. Attenuating the p53 Pathway in Human Cancers: Many Means to the Same End.

    Science.gov (United States)

    Wasylishen, Amanda R; Lozano, Guillermina

    2016-01-01

    The p53 pathway is perturbed in the majority of human cancers. Although this most frequently occurs through the direct mutation or deletion of p53 itself, there are a number of other alterations that can attenuate the pathway and contribute to tumorigenesis. For example, amplification of important negative regulators, MDM2 and MDM4, occurs in a number of cancers. In this work, we will review both the normal regulation of the p53 pathway and the different mechanisms of pathway inhibition in cancer, discuss these alterations in the context of the global genomic analyses that have been conducted across tumor types, and highlight the translational implications for cancer diagnosis and treatment. PMID:27329033

  11. Mutant p53 in cell adhesion and motility.

    Science.gov (United States)

    Yeudall, W Andrew; Wrighton, Katharine H; Deb, Sumitra

    2013-01-01

    Pro-oncogenic properties of mutant p53 were investigated with the aid of migration assays, adhesion assays, and soft agar growth assays using cells stably expressing gain-of-function p53 mutants. To determine cell migration, "wound-healing" (scratch) assays and haptotactic (chamber) assays were used. H1299 cells expressing mutant p53 were found to migrate more rapidly than cells transfected with empty vector alone. Results from both types of migration assay were broadly similar. Migratory ability differed for different p53 mutants, suggesting allele-specific effects. Cells expressing p53 mutants also showed enhanced adhesion to extracellular matrix compare to controls. Furthermore, stable transfection of mutant p53-H179L into NIH3T3 fibroblasts was sufficient to allow anchorage-independent growth in soft agar. PMID:23150443

  12. New microRNAS regulating the P53 signaling pathway

    OpenAIRE

    Bisso, Andrea

    2010-01-01

    A vast body of evidence from clinical and basic research studies has demonstrated that the p53 pathway acts as an essential barrier in preventing cancer onset and development. ------------------------ A vast body of evidence from clinical and basic research studies has demonstrated that the p53 pathway acts as an essential barrier in preventing cancer onset and development. p53 receives and integrates a wide variety of cytotoxic and genotoxic stress signals from upstream sensors transla...

  13. Regulation of MCP-1 chemokine transcription by p53

    Directory of Open Access Journals (Sweden)

    Wasylyk Bohdan

    2010-04-01

    Full Text Available Abstract Background Our previous studies showed that the expression of the monocyte-chemoattractant protein (MCP-1, a chemokine, which triggers the infiltration and activation of cells of the monocyte-macrophage lineage, is abrogated in human papillomavirus (HPV-positive premalignant and malignant cells. In silico analysis of the MCP-1 upstream region proposed a putative p53 binding side about 2.5 kb upstream of the transcriptional start. The aim of this study is to monitor a physiological role of p53 in this process. Results The proposed p53 binding side could be confirmed in vitro by electrophoretic-mobility-shift assays and in vivo by chromatin immunoprecipitation. Moreover, the availability of p53 is apparently important for chemokine regulation, since TNF-α can induce MCP-1 only in human keratinocytes expressing the viral oncoprotein E7, but not in HPV16 E6 positive cells, where p53 becomes degraded. A general physiological role of p53 in MCP-1 regulation was further substantiated in HPV-negative cells harboring a temperature-sensitive mutant of p53 and in Li-Fraumeni cells, carrying a germ-line mutation of p53. In both cases, non-functional p53 leads to diminished MCP-1 transcription upon TNF-α treatment. In addition, siRNA directed against p53 decreased MCP-1 transcription after TNF-α addition, directly confirming a crosstalk between p53 and MCP-1. Conclusion These data support the concept that p53 inactivation during carcinogenesis also affects immune surveillance by interfering with chemokine expression and in turn communication with cells of the immunological compartment.

  14. Influence of p53-regulated energy metabolism in radiation effects

    International Nuclear Information System (INIS)

    p53 is a hot spot in the studies of tumor etiology and radiobiology, but the function of p53-regulated energy metabolism in radiation biological effects still remains many uncertainties. The in-depth study of p53-regulated energy metabolism is of great significance to investigate the tumor radiotherapy efficacy, radiation damage, carcinogenesis and even molecular epidemiology. The current research progress at this point was stated in this article. (authors)

  15. Effect of p53 on mitochondrial morphology, import, and assembly in skeletal muscle.

    Science.gov (United States)

    Saleem, Ayesha; Iqbal, Sobia; Zhang, Yuan; Hood, David A

    2015-02-15

    The purpose of this study was to investigate whether p53 regulates mitochondrial function via changes in mitochondrial protein import, complex IV (COX) assembly, or the expression of key proteins involved in mitochondrial dynamics and degradation. Mitochondria from p53 KO mice displayed ultra-structural alterations and were more punctate in appearance. This was accompanied by protein-specific alterations in fission, fusion, and mitophagy-related proteins. However, matrix-destined protein import into subsarcolemmal or intermyofibrillar mitochondria was unaffected in the absence of p53, despite mitochondrial subfraction-specific reductions in Tom20, Tim23, mtHsp70, and mtHsp60 in the knockout (KO) mitochondria. Complex IV activity in isolated mitochondria was also unchanged in KO mice, but two-dimensional blue native-PAGE revealed a reduction in the assembly of complex IV within the IMF fractions from KO mice in tandem with lower levels of the assembly protein Surf1. This observed defect in complex IV assembly may facilitate the previously documented impairment in mitochondrial function in p53 KO mice. We suspect that these morphological and functional impairments in mitochondria drive a decreased reliance on mitochondrial respiration as a means of energy production in skeletal muscle in the absence of p53. PMID:25472962

  16. Wild-type alternatively spliced p53: binding to DNA and interaction with the major p53 protein in vitro and in cells.

    OpenAIRE

    Wu, Y.; Liu, Y; Lee, L.(Department of Physics, Yale University, New Haven, CT, USA); Miner, Z; Kulesz-Martin, M

    1994-01-01

    A p53 variant protein (p53as) generated from alternatively spliced p53 RNA is expressed in normal and malignant mouse cells and tissues, and p53as antigen activity is preferentially associated with the G2 phase of the cell cycle, suggesting that p53as and p53 protein may have distinct properties. Using p53as and p53 proteins translated in vitro, we now provide evidence that p53as protein has efficient sequence-specific DNA-binding ability. DNA binding by p53 protein is inefficient in comparis...

  17. Resistance of mitochondrial p53 to dominant inhibition

    OpenAIRE

    Mestres Pedro; Armbruester Vivienne; Mueller Daniel; Schmitt Katrin; Heyne Kristina; Roemer Klaus

    2008-01-01

    Abstract Background Mutation of a tumor suppressor allele leaves the second as backup. Not necessarily so with p53. This homo-tetrameric transcription factor can become contaminated with mutant p53 through hetero-tetramerization. In addition, it can be out-competed by the binding to p53 DNA recognition motifs of transactivation-incompetent isoforms (ΔN and ΔTA-isoforms) of the p53/p63/p73 family of proteins. Countermeasures against such dominant-negative or dominant-inhibitory action might in...

  18. MEKK1/JNK signaling stabilizes and activates p53

    OpenAIRE

    Fuchs, Serge Y.; Adler, Victor; Pincus, Matthew R.; Ronai, Ze’ev

    1998-01-01

    Activation of the tumor suppressor p53 by stress and damage stimuli often correlates with induction of stress kinases, Jun-NH2 kinase (JNK). As JNK association with p53 plays an important role in p53 stability, in the present study we have elucidated the relationship between the JNK-signaling pathway and p53 stability and activity. Expression of a constitutively active form of JNKK upstream kinase, mitogen-activated protein kinase kinase kinase (ΔMEKK1), increased the level of the exogenously...

  19. p53 Antibody and Malignant Tumor%p53抗体与恶性肿瘤

    Institute of Scientific and Technical Information of China (English)

    曾常茜; 王振明

    2002-01-01

    p53基因是人类肿瘤中突变频率最高的抑癌基因,几乎发生于所有的恶性肿瘤.突变基因编码的p53蛋白释放入血,可诱发机体自身免疫应答,产生p53自身抗体.在肿瘤病人和高危人群中检测血清p53抗体可以反映早期p53基因突变,作为一种新的肿瘤生物学指标,p53抗体有望在恶性肿瘤的早期诊断、治疗、预后、监测、复发等方面发挥重要作用.

  20. The Proteasome Activator PA28γ, a Negative Regulator of p53, Is Transcriptionally Up-Regulated by p53

    Directory of Open Access Journals (Sweden)

    Zhen-Xing Wan

    2014-02-01

    Full Text Available PA28γ (also called REGγ, 11Sγ or PSME3 negatively regulates p53 activity by promoting its nuclear export and/or degradation. Here, using the RNA ligase-mediated rapid amplification of cDNA ends (RLM-RACE method, we identified the transcription start site of the PA28γ gene. Assessment with the luciferase assay demonstrated that the sequence −193 to +16 is the basal promoter. Three p53 binding sites were found within the PA28γ promoter utilizing a bioinformatics approach and were confirmed by chromatin immunoprecipitation and biotinylated DNA affinity precipitation experiments. The p53 protein promotes PA28γ transcription, and p53-stimulated transcription of PA28γ can be inhibited by PA28γ itself. Our results suggest that PA28γ and p53 form a negative feedback loop, which maintains the balance of p53 and PA28γ in cells.

  1. Induction of wild-type p53 activity in human cancer cells by ribozymes that repair mutant p53 transcripts

    OpenAIRE

    Watanabe, Takashi; Sullenger, Bruce A

    2000-01-01

    Several groups have attempted to develop gene therapy strategies to treat cancer via introduction of the wild-type (wt) p53 cDNA into cancer cells. Unfortunately, these approaches do not result in regulated expression of the p53 gene and do not reduce expression of the mutant p53 that is overexpressed in cancerous cells. These shortcomings may greatly limit the utility of this gene replacement approach. We describe an alternative strategy with trans-splicing ribozymes that can simultaneously ...

  2. Modeling the basal dynamics of p53 system.

    Directory of Open Access Journals (Sweden)

    Tingzhe Sun

    Full Text Available BACKGROUND: The tumor suppressor p53 has become one of most investigated genes. Once activated by stress, p53 leads to cellular responses such as cell cycle arrest and apoptosis. METHODOLOGY/PRINCIPAL FINDINGS: Most previous models have ignored the basal dynamics of p53 under nonstressed conditions. To explore the basal dynamics of p53, we constructed a stochastic delay model by incorporating two negative feedback loops. We found that protein distribution of p53 under nonstressed condition is highly skewed with a fraction of cells showing high p53 levels comparable to those observed under stressed conditions. Under nonstressed conditions, asynchronous and spontaneous p53 pulses are triggered by basal DNA double strand breaks produced during normal cell cycle progression. The first peaking times show a predominant G1 distribution while the second ones are more widely distributed. The spontaneous pulses are triggered by an excitable mechanism. Once initiated, the amplitude and duration of pulses remain unchanged. Furthermore, the spontaneous pulses are filtered by ataxia telangiectasia mutated protein mediated posttranslational modifications and do not result in substantial p21 transcription. If challenged by externally severe DNA damage, cells generate synchronous p53 pulses and induce significantly high levels of p21. The high expression of p21 can also be partially induced by lowering the deacetylation rate. CONCLUSIONS: Our results demonstrated that the dynamics of p53 under nonstressed conditions is initiated by an excitable mechanism and cells become fully responsive only when cells are confronted with severe damage. These findings advance our understanding of the mechanism of p53 pulses and unlock many opportunities to p53-based therapy.

  3. Impact of cadmium on hOGG1 and APE1 as a function of the cellular p53 status

    International Nuclear Information System (INIS)

    The tumor suppressor protein p53, often called the guardian of the genome, is involved in important cellular processes, such as cell cycle control, apoptosis and DNA repair. With respect to BER, p53 might physically interact with and affect the transcription of different BER proteins such as hOGG1, APE1 or Polβ. In studies in HCT116 p53−/− cells previously published, activity and mRNA expression of hOGG1 were found to be significantly decreased, while down-regulation of APE1 mRNA and protein levels in response to genotoxic stress were only described in HCT116 p53+/+ cells, but not in the isogenic p53 knockout cell line. The predominantly indirect genotoxic carcinogen cadmium inhibits the BER pathway and potentially interferes with zinc binding proteins such as p53. Therefore, this study was accomplished to investigate whether p53 is involved in the cadmium-induced inhibition of BER activity. To address this issue we applied a non-radioactive cleavage test system based on a Cy5-labeled oligonucleotide. We present evidence that p53 is not essential for hOGG1 and APE1 gene expression as well as OGG and APE activity in unstressed HCT116 cells; however, it plays an important role in the cellular response to cadmium treatment. Here, a direct involvement of p53 was only observed with respect to APE1 gene expression contributing to an altered APE activity, while OGG activity was presumably affected indirectly due to a stronger accumulation of cadmium in HCT116 p53+/+ cells. In summary, p53 indeed affects the BER pathway directly and indirectly in response to cadmium treatment.

  4. Epstein-Barr virus nuclear antigen 3C targets p53 and modulates its transcriptional and apoptotic activities

    International Nuclear Information System (INIS)

    The p53 tumor suppressor gene is one of the most commonly mutated genes in human cancers and the corresponding encoded protein induces apoptosis or cell-cycle arrest at the G1/S checkpoint in response to DNA damage. To date, previous studies have shown that antigens encoded by human tumor viruses such as SV40 large T antigen, adenovirus E1A and HPV E6 interact with p53 and disrupt its functional activity. In a similar fashion, we now show that EBNA3C, one of the EBV latent antigens essential for the B-cell immortalization in vitro, interacts directly with p53. Additionally, we mapped the interaction of EBNA3C with p53 to the C-terminal DNA-binding and the tetramerization domain of p53, and the region of EBNA3C responsible for binding to p53 was mapped to the N-terminal domain of EBNA3C (residues 130-190), previously shown to interact with a number of important cell-cycle components, specifically SCFSkp2, cyclin A, and cMyc. Furthermore, we demonstrate that EBNA3C substantially represses the transcriptional activity of p53 in luciferase based reporter assays, and rescues apoptosis induced by ectopic p53 expression in SAOS-2 (p53-/-) cells. Interestingly, we also show that the DNA-binding ability of p53 is diminished in the presence of EBNA3C. Thus, the interaction between the p53 and EBNA3C provides new insights into the mechanism(s) by which the EBNA3C oncoprotein can alter cellular gene expression in EBV associated human cancers.

  5. P53 Gene Mutation and Expression of MDM2, P53, P16 Protein and their Relationship in Human Glioma

    Institute of Scientific and Technical Information of China (English)

    CUI Wen; WU Renliang; CAO Huiling; GAO Jifa; WANG Xu; REN Qiwei

    2005-01-01

    To investigate the effect of P53 protein accumulation and p53 gene mutation in the pathogenesis of glioma and to study the role of MDM2, P53 and P16 protein in glioma formation and progression and their relationship with each other, LSAB immunohistochemical staining method and non-isotopic PCR-SSCP techniques were used to detect the expression of MDM2, P53 and P16 pro tein and p53 gene mutation in 48 cases of gliomas. The results showed that the positive expression rate of MDM2, P53 and the negative rate of P16 was 22.9 %, 41.7 % and 60.4 %, respectively.The latter two in high grade (grade Ⅲ , Ⅳ) gliomas had a significantly higher rate than in the low grade (grade Ⅱ ) gliomas. Moreover, the co-expression of MDM2 and P53 protein was confirmed in only 1 of 48 cases. No significant difference was found in the rate of the expression of MDM2 between high grade and low grade gliomas (P>0.1) . PCR SSCP results showed that mutation of 5-8 exons of p53 gene was detected in 17 out of 48 cases (35.42 %) . Mutation was detected in 16of 20 cases of positive p53 expression, and another one was detected in 28 cases of negative expression cases. The correlation between p53 mutation and p53 immunopositivity was observed in 89.6% of the cases. P53 gene mutation and the level of MDM2, P53 and P16 protein were not related to age, gender of the patients, tumor location and size. It is concluded that the mutation of p53 and deletion of p16 might play important roles in the tumorigenesis of gliomas and it was significantly associated with the grade of tumor differentiation. P53 protein accumulation can indirectly reflect p53 mutation. MDM2 amplification and overexpression might be an early event in the growth of human gliomas.

  6. Dmp1 physically interacts with p53 and positively regulates p53’s stability, nuclear localization, and function

    OpenAIRE

    Frazier, Donna P.; Kendig, Robert D.; Kai, Fumitake; Maglic, Dejan; Sugiyama, Takayuki; Rachel L. Morgan; Fry, Elizabeth A.; Lagedrost, Sarah J.; Sui, Guangchao; Inoue, Kazushi

    2012-01-01

    The transcription factor Dmp1 is a Ras/HER2-activated haplo-insufficient tumor suppressor that activates the Arf/p53 pathway of cell cycle arrest. Recent evidence suggests that Dmp1 may activate p53 independently of Arf in certain cell types. Here we report findings supporting this concept with the definition an Arf-independent function for Dmp1 in tumor suppression. We found that Dmp1 and p53 can interact directly in mammalian cells via the carboxyl-terminus of p53 and the DNA-binding domain...

  7. Comparative analysis of P16 and P53 expression in uterine malignant mixed mullerian tumors.

    Science.gov (United States)

    Buza, Natalia; Tavassoli, Fattaneh A

    2009-11-01

    Recent studies have shown that, in addition to cervical carcinomas, a substantial proportion of endometrial adenocarcinomas are also immunoreactive with p16. The expression of p16 in uterine malignant mixed mullerian tumors (MMMTs), in contrast, has not yet been analyzed in a large series. To our knowledge, we present the first study assessing p16 expression in both components of MMMTs. We performed p16 and p53 immunostains on 30 cases of uterine MMMTs. Both the epithelial and mesenchymal components were subclassified; p16 and p53 immunoreactions were assessed using a semiquantitative scoring system. p16 overexpression was noted in the carcinomatous component in 96.7% (29/30), and in the sarcomatous component in 86.7% (26/30) of cases. In comparison, p53 immunoreactivity was present in the carcinomatous component in 76.7% (23/30), and in the sarcomatous component in 83.3% (25/30) of cases. p16 immunoreactivity was more intense and diffuse than p53 in 40% of type I, 30% of type II carcinomas, and 27% of sarcomatous components. There was no significant difference in p16 or p53 immunoreactivity between the homologous and heterologous sarcomas. The concordance rates for p16 and p53 immunoreactivity between the 2 components were 83% and 90%, respectively. We conclude that p16 immunostain is positive in the vast majority of uterine MMMTs with no significant difference in staining between the 2 components. Compared with p53, p16 immunoreactivity is significantly more intense and diffuse in both components. Our findings indicate that alterations in the p16-Rb pathway play an important role in the pathogenesis of uterine MMMTs. PMID:19851197

  8. A limited role for p53 in modulating the immediate phenotype of Apc loss in the intestine

    International Nuclear Information System (INIS)

    p53 is an important tumour suppressor with a known role in the later stages of colorectal cancer, but its relevance to the early stages of neoplastic initiation remains somewhat unclear. Although p53-dependent regulation of Wnt signalling activity is known to occur, the importance of these regulatory mechanisms during the early stages of intestinal neoplasia has not been demonstrated. We have conditionally deleted the Adenomatous Polyposis coli gene (Apc) from the adult murine intestine in wild type and p53 deficient environments and subsequently compared the phenotype and transcriptome profiles in both genotypes. Expression of p53 was shown to be elevated following the conditional deletion of Apc in the adult small intestine. Furthermore, p53 status was shown to impact on the transcription profile observed following Apc loss. A number of key Wnt pathway components and targets were altered in the p53 deficient environment. However, the aberrant phenotype observed following loss of Apc (rapid nuclear localisation of β-catenin, increased levels of DNA damage, nuclear atypia, perturbed cell death, proliferation, differentiation and migration) was not significantly altered by the absence of p53. p53 related feedback mechanisms regulating Wnt signalling activity are present in the intestine, and become activated following loss of Apc. However, the physiological Wnt pathway regulation by p53 appears to be overwhelmed by Apc loss and consequently the activity of these regulatory mechanisms is not sufficient to modulate the immediate phenotypes seen following Apc loss. Thus we are able to provide an explanation to the apparent contradiction that, despite having a Wnt regulatory capacity, p53 loss is not associated with early lesion development

  9. Exploring a minimal two-component p53 model

    International Nuclear Information System (INIS)

    The tumor suppressor p53 coordinates many attributes of cellular processes via interlocked feedback loops. To understand the biological implications of feedback loops in a p53 system, a two-component model which encompasses essential feedback loops was constructed and further explored. Diverse bifurcation properties, such as bistability and oscillation, emerge by manipulating the feedback strength. The p53-mediated MDM2 induction dictates the bifurcation patterns. We first identified irradiation dichotomy in p53 models and further proposed that bistability and oscillation can behave in a coordinated manner. Further sensitivity analysis revealed that p53 basal production and MDM2-mediated p53 degradation, which are central to cellular control, are most sensitive processes. Also, we identified that the much more significant variations in amplitude of p53 pulses observed in experiments can be derived from overall amplitude parameter sensitivity. The combined approach with bifurcation analysis, stochastic simulation and sampling-based sensitivity analysis not only gives crucial insights into the dynamics of the p53 system, but also creates a fertile ground for understanding the regulatory patterns of other biological networks

  10. Human p53 oncogene contains one promoter upstream of exon 1 and a second, stronger promoter within intron 1

    International Nuclear Information System (INIS)

    To gain insight into how transcription of the human p53 oncogene is controlled, the authors characterized the regulatory regions of the gene. A 3.8-kilobase-pair (kbp) EcoRI restriction fragment encompassing the 5' end of the human p53 gene, as well as subfragments generated by restriction digests, was cloned upstream of the Escherichia coli chloramphenicol acetyltransferase (CAT) gene and CAT activity was assayed in extracts of transfected cells. Two types of CAT vectors were used: Epstein-Barr virus oriP-derived constructs that were stably introduced into the human cell lines K562, Raji, and HL-60, and pSVO-CAT-derived constructs that were transiently introduced into the monkey cell line COS. By this approach they have identified two promoters for the human p53 gene. One promoter, p53P1, is located 100-250 bp upstream of the 218-bp noncoding first exon; a second, stronger promoter, p53P2, maps within the first intron. CAT activity and expression of CAT RNA indicate that p53P2 functions up to 50-fold more efficiently than p53P1. They conclude that the expression of the human p53 gene may be controlled by two promoters and that differential regulation of these promoters may play an important role in the altered expression of the gene in both normal and transformed cells

  11. Over-expression of tumour suppressor gene p53 in laryngeal squamous cell carcinomas and its prognostic significance.

    Science.gov (United States)

    Salam, M A; Crocker, J; Morris, A

    1995-02-01

    p53 is a nuclear phosphoprotein which acts as a tumour suppressor factor, regulating cell growth and division. Mutations in the p53 gene appear to be the most common genetic alterations in human cancer. The aim of this study was to investigate p53 expression in laryngeal squamous cell carcinomas and to assess its role as a marker of prognostic significance. Using immunohistochemical staining techniques, a series of laryngeal carcinomas (n = 87) were examined for expression of the mutant form of p53 phosphoprotein using the monoclonal antibody PAB 1801. p53 over-expression was noted in 50 biopsies of laryngeal carcinomas (57.5%) but not in any of the non-neoplastic laryngeal mucosa which were used as the control. There was no statistical correlation between p53 immunoreactivity and the clinicopathological parameters of the cancers including: site of tumour, TNM staging, differentiation grading and tumour recurrence. These findings indicate that p53 expression is strongly associated with carcinoma cells and not with normal cells in the larynx. However, p53 expression is probably unrelated to the biological aggressiveness of these tumours. PMID:7788934

  12. Mdm2 is a novel activator of ApoCIII promoter which is antagonized by p53 and SHP inhibition

    International Nuclear Information System (INIS)

    Highlights: ► Mdm2 enhances HNF4α activation of the ApoCIII promoter via interaction with HNF4α. ► p53 antagonizes the effect of Mdm2 activation of the ApoCIII promoter. ► SHP strengthens p53 inhibition but abolishes Mdm2 activation of the ApoCIII promoter. ► Mdm2 alters the enrichment of HNF4α, p53 and SHP to the ApoCIII promoter. -- Abstract: We examined the effect of Mdm2 on regulation of the ApoCIII promoter and its cross-talk with p53 and nuclear receptor SHP. Overexpression of Mdm2 markedly enhanced ApoCIII promoter activity by HNF4α. A direct association of Mdm2 protein with the HNF4α protein was observed by co-immunoprecipitation. Ectopic expression of p53 decreased HNF4α activation of the ApoCIII promoter and antagonized the effect of Mdm2. Co-expression of SHP further strengthened p53 inhibition and abolished Mdm2 activation of the ApoCIII promoter. Mdm2 inhibited p53-mediated enrichment of HNF4α to the ApoCIII promoter while simultaneously reducing p53 binding and increasing recruitment of SHP to the ApoCIII promoter. The results from this study implicate a potentially important function of Mdm2 in regulation of lipoprotein metabolism.

  13. COX-2 and p53 in human sinonasal cancer

    DEFF Research Database (Denmark)

    Holmila, Reetta; Cyr, Diane; Luce, Danièle;

    2008-01-01

    to development of cancer. Many signals that activate COX-2 also induce tumor suppressor p53, a transcription factor central in cellular stress response. We investigated COX-2 and p53 expressions by immunohistochemistry in 50 SNCs (23 adenocarcinomas, and 27 squamous cell carcinomas (SCC); 48 analyzed...... for COX-2; 41 for p53). Occupational histories and smoking habits were available for majority of the cases. Most of the adenocarcinoma cases with exposure history data had been exposed to wood dust at work in the past (88%, 14/16). For smokers, 63% (12/19) presented with SSC, whereas 64% (7/11) of...... between the exposures and p53 accumulation were found; however, the p53 accumulation pattern (p = 0.062 for wood dust exposure) resembled that of COX-2 expression. In summary, our findings show increased COX-2 expression in SNC adenocarcinoma with wood dust exposure, suggesting a role for inflammatory...

  14. pCLPG: a p53-driven retroviral system

    International Nuclear Information System (INIS)

    We have modified the pCL retroviral system by the insertion of a p53-responsive element, called PG, in the U3 region of the 3'-LTR, either in addition to or in place of the native negative control region/enhancer sequence. We show here that either endogenous or exogenous wild-type p53 may be used to drive expression from the pCLPG system in transduced cells. Upon genotoxic induction of endogenous p53, pCLPG expression surpassed that of the parental, nonmodified virus, specifically when the native promoter was removed and substituted by the p53-responsive element. We propose that the novel pCLPG system will prove to be a valuable tool whether used as a reporter system of p53 function or as an in vitro and in vivo gene transfer vehicle

  15. Retardation of cell growth by avian reovirus p17 through the activation of p53 pathway

    International Nuclear Information System (INIS)

    The second open reading frame of avian reovirus S1 gene segment encodes a 17 kDa non-structural protein, named p17. The biological role of p17 is fully unknown so far. Using trypan blue dye exclusion and MTT assay, we demonstrated that the ectopic expression of p17 results in the reduction of viable cell number and cell proliferation rate of Vero, BHK, 293, and HeLa cells. Measurement of LDH activity and DNA fragmentation analysis revealed that p17 expression did not cause cell death or apoptosis. These data indicated that the p17 possessed the growth retardation function. Semi-quantitative RT-PCR and Western blotting revealed that p17-expressing cells induced the expression of CDK inhibitor p21cip1/waf1 in a time- and dose-dependent manner, but the transcripts of CDK inhibitor p15INK4b, p16INK4a, or p27kip were not altered. In the presence of p17, the p53 protein level and p53-driven reporter activity were elevated significantly. Dominant negative p53 alleviated the p21 accumulation, p53 activation, and growth inhibition effect induced by p17. Taken together, these studies revealed a possible intrinsic function of p17 in growth regulation through the activation of p53 and p21cip1/waf1

  16. Mitochondrial dysfunction impairs tumor suppressor p53 expression/function.

    Science.gov (United States)

    Compton, Shannon; Kim, Chul; Griner, Nicholas B; Potluri, Prasanth; Scheffler, Immo E; Sen, Sabyasachi; Jerry, D Joseph; Schneider, Sallie; Yadava, Nagendra

    2011-06-10

    Recently, mitochondria have been suggested to act in tumor suppression. However, the underlying mechanisms by which mitochondria suppress tumorigenesis are far from being clear. In this study, we have investigated the link between mitochondrial dysfunction and the tumor suppressor protein p53 using a set of respiration-deficient (Res(-)) mammalian cell mutants with impaired assembly of the oxidative phosphorylation machinery. Our data suggest that normal mitochondrial function is required for γ-irradiation (γIR)-induced cell death, which is mainly a p53-dependent process. The Res(-) cells are protected against γIR-induced cell death due to impaired p53 expression/function. We find that the loss of complex I biogenesis in the absence of the MWFE subunit reduces the steady-state level of the p53 protein, although there is no effect on the p53 protein level in the absence of the ESSS subunit that is also essential for complex I assembly. The p53 protein level was also reduced to undetectable levels in Res(-) cells with severely impaired mitochondrial protein synthesis. This suggests that p53 protein expression is differentially regulated depending upon the type of electron transport chain/respiratory chain deficiency. Moreover, irrespective of the differences in the p53 protein expression profile, γIR-induced p53 activity is compromised in all Res(-) cells. Using two different conditional systems for complex I assembly, we also show that the effect of mitochondrial dysfunction on p53 expression/function is a reversible phenomenon. We believe that these findings will have major implications in the understanding of cancer development and therapy. PMID:21502317

  17. p53 regulates the transcription of its Delta133p53 isoform through specific response elements contained within the TP53 P2 internal promoter.

    Science.gov (United States)

    Marcel, V; Vijayakumar, V; Fernández-Cuesta, L; Hafsi, H; Sagne, C; Hautefeuille, A; Olivier, M; Hainaut, P

    2010-05-01

    The tumor suppressor p53 protein is activated by genotoxic stress and regulates genes involved in senescence, apoptosis and cell-cycle arrest. Nine p53 isoforms have been described that may modulate suppressive functions of the canonical p53 protein. Among them, Delta133p53 lacks the 132 proximal residues and has been shown to modulate p53-induced apoptosis and cell-cycle arrest. Delta133p53 is expressed from a specific mRNA, p53I4, driven by an alternative promoter P2 located between intron 1 and exon 5 of TP53 gene. Here, we report that the P2 promoter is regulated in a p53-dependent manner. Delta133p53 expression is increased in response to DNA damage by doxorubicin in p53 wild-type cell lines, but not in p53-mutated cells. Chromatin immunoprecipitation and luciferase assays using P2 promoter deletion constructs indicate that p53 binds functional response elements located within the P2 promoter. We also show that Delta133p53 does not bind specifically to p53 consensus DNA sequence in vitro, but competes with wild-type p53 in specific DNA-binding assays. Finally, we report that Delta133p53 counteracts p53-dependent growth suppression in clonogenic assays. These observations indicate that Delta133p53 is a novel target of p53 that may participate in a negative feedback loop controlling p53 function. PMID:20190805

  18. Fuzzy tandem repeats containing p53 response elements may define species-specific p53 target genes.

    Directory of Open Access Journals (Sweden)

    Iva Simeonova

    2012-06-01

    Full Text Available Evolutionary forces that shape regulatory networks remain poorly understood. In mammals, the Rb pathway is a classic example of species-specific gene regulation, as a germline mutation in one Rb allele promotes retinoblastoma in humans, but not in mice. Here we show that p53 transactivates the Retinoblastoma-like 2 (Rbl2 gene to produce p130 in murine, but not human, cells. We found intronic fuzzy tandem repeats containing perfect p53 response elements to be important for this regulation. We next identified two other murine genes regulated by p53 via fuzzy tandem repeats: Ncoa1 and Klhl26. The repeats are poorly conserved in evolution, and the p53-dependent regulation of the murine genes is lost in humans. Our results indicate a role for the rapid evolution of tandem repeats in shaping differences in p53 regulatory networks between mammalian species.

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

    Science.gov (United States)

    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. PMID:26992014

  20. Inhibition of oxidative metabolism leads to p53 genetic inactivation and transformation in neural stem cells.

    Science.gov (United States)

    Bartesaghi, Stefano; Graziano, Vincenzo; Galavotti, Sara; Henriquez, Nick V; Betts, Joanne; Saxena, Jayeta; Minieri, Valentina; A, Deli; Karlsson, Anna; Martins, L Miguel; Capasso, Melania; Nicotera, Pierluigi; Brandner, Sebastian; De Laurenzi, Vincenzo; Salomoni, Paolo

    2015-01-27

    Alterations of mitochondrial metabolism and genomic instability have been implicated in tumorigenesis in multiple tissues. High-grade glioma (HGG), one of the most lethal human neoplasms, displays genetic modifications of Krebs cycle components as well as electron transport chain (ETC) alterations. Furthermore, the p53 tumor suppressor, which has emerged as a key regulator of mitochondrial respiration at the expense of glycolysis, is genetically inactivated in a large proportion of HGG cases. Therefore, it is becoming evident that genetic modifications can affect cell metabolism in HGG; however, it is currently unclear whether mitochondrial metabolism alterations could vice versa promote genomic instability as a mechanism for neoplastic transformation. Here, we show that, in neural progenitor/stem cells (NPCs), which can act as HGG cell of origin, inhibition of mitochondrial metabolism leads to p53 genetic inactivation. Impairment of respiration via inhibition of complex I or decreased mitochondrial DNA copy number leads to p53 genetic loss and a glycolytic switch. p53 genetic inactivation in ETC-impaired neural stem cells is caused by increased reactive oxygen species and associated oxidative DNA damage. ETC-impaired cells display a marked growth advantage in the presence or absence of oncogenic RAS, and form undifferentiated tumors when transplanted into the mouse brain. Finally, p53 mutations correlated with alterations in ETC subunit composition and activity in primary glioma-initiating neural stem cells. Together, these findings provide previously unidentified insights into the relationship between mitochondria, genomic stability, and tumor suppressive control, with implications for our understanding of brain cancer pathogenesis. PMID:25583481

  1. Prognostic value of the hDMP1-ARF-Hdm2-p53 pathway in breast cancer

    OpenAIRE

    Maglic, Dejan; Zhu, Sinan; Taneja, Pankaj; Fry, Elizabeth A.; Kai, Fumitake; Kendig, Robert D.; Sugiyama, Takayuki; Miller, Lance D.; Willingham, Mark C.; Inoue, Kazushi

    2012-01-01

    Our recent study showed critical roles of Dmp1 as a sensor of oncogenic Ras, HER2/neu signaling and activation of the Arf-p53 pathway. To elucidate the role of human DMP1 (hDMP1) in breast cancer, one hundred and ten pairs of human breast cancer specimen were studied for the alterations of the hDMP1-ARF-Hdm2-p53 pathway with follow up of clinical outcomes. Loss of heterozygosity (LOH) of the hDMP1 locus was found in 42% of human breast carcinomas, while that of INK4a/ARF and p53 were found in...

  2. Cisplatinum and Taxol Induce Different Patterns of p53 Phosphorylation

    Directory of Open Access Journals (Sweden)

    Giovanna Damia

    2001-01-01

    Full Text Available Posttranslational modifications of p53 induced by two widely used anticancer agents, cisplatinum (DDP and taxol were investigated in two human cancer cell lines. Although both drugs were able to induce phosphorylation at serine 20 (Ser20, only DDP treatment induced p53 phosphorylation at serine 15 (Ser15. Moreover, both drug treatments were able to increase p53 levels and consequently the transcription of waf1 and mdm-2 genes, although DDP treatment resulted in a stronger inducer of both genes. Using two ataxia telangiectasia mutated (ATM cell lines, the role of ATM in druginduced p53 phosphorylations was investigated. No differences in drug-induced p53 phosphorylation could be observed, indicating that ATM is not the kinase involved in these phosphorylation events. In addition, inhibition of DNA-dependent protein kinase activity by wortmannin did not abolish p53 phosphorylation at Ser15 and Ser20, again indicating that DNA-PK is unlikely to be the kinase involved. After both taxol and DDP treatments, an activation of hCHK2 was found and this is likely to be responsible for phosphorylation at Ser20. In contrast, only DDP was able to activate ATR, which is the candidate kinase for phosphorylation of Ser15 by this drug. This data clearly suggests that differential mechanisms are involved in phosphorylation and activation of p53 depending on the drug type.

  3. HEXIM1, a New Player in the p53 Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Lew, Qiao Jing; Chu, Kai Ling; Chia, Yi Ling; Cheong, Nge [Expression Engineering Group, Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way, #06-01, Singapore 138668 (Singapore); Chao, Sheng-Hao, E-mail: jimmy_chao@bti.a-star.edu.sg [Expression Engineering Group, Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way, #06-01, Singapore 138668 (Singapore); Department of Microbiology, National University of Singapore, Singapore 117597 (Singapore)

    2013-07-04

    Hexamethylene bisacetamide-inducible protein 1 (HEXIM1) is best known as the inhibitor of positive transcription elongation factor b (P-TEFb), which controls transcription elongation of RNA polymerase II and Tat transactivation of human immunodeficiency virus. Besides P-TEFb, several proteins have been identified as HEXIM1 binding proteins. It is noteworthy that more than half of the HEXIM1 binding partners are involved in cancers. P53 and two key regulators of the p53 pathway, nucleophosmin (NPM) and human double minute-2 protein (HDM2), are among the factors identified. This review will focus on the functional importance of the interactions between HEXIM1 and p53/NPM/HDM2. NPM and the cytoplasmic mutant of NPM, NPMc+, were found to regulate P-TEFb activity and RNA polymerase II transcription through the interaction with HEXIM1. Importantly, more than one-third of acute myeloid leukemia (AML) patients carry NPMc+, suggesting the involvement of HEXIM1 in tumorigenesis of AML. HDM2 was found to ubiquitinate HEXIM1. The HDM2-mediated ubiquitination of HEXIM1 did not lead to protein degradation of HEXIM1 but enhanced its inhibitory activity on P-TEFb. Recently, HEXIM1 was identified as a novel positive regulator of p53. HEXIM1 prevented p53 ubiquitination by competing with HDM2 in binding to p53. Taken together, the new evidence suggests a role of HEXIM1 in regulating the p53 pathway and tumorigenesis.

  4. p53-dependent apoptosis suppresses radiation-induced teratogenesis

    International Nuclear Information System (INIS)

    About half of human conceptions are estimated not to be implanted in the uterus, resulting in unrecognizable spontaneous abortions. Experimental studies with mice have established that irradiation during the preimplantation period of the embryo induces a high incidence of prenatal deaths but virtually no malformations. This suggests that some mechanism is screening out the damaged fetuses. In order to elucidate the mechanisms of tissue repair of radiation-induced teratogenic injury, we compared the incidences of radiation-induced malformations and abortions in p53 null (p53-/-) and wild-type (p53+/+) mice. After X-irradiation with 2 Gy on day 9.5 of gestation, p53-/- mice showed a 70% incidence of anomalies and a 7% incidence of deaths, whereas p53+/+ mice had a 20% incidence of anomalies and a 60% incidence of deaths. Similar results were obtained after irradiation on day 3.5 of gestation. This reciprocal relationship of radiosensitivity to anomalies and to embryonic or fetal lethality supports the notion that the p53 gene protects embryos and fetuses against the teratogenic effects of radiation by eliminating cells that have been badly damaged. In fact, after X-irradiation, the frequency of dying cells by apoptosis was greatly increased in tissues of the p53+/+ fetuses but not at all in those of the p53-/- fetuses. Mammals are protected from radiation-induced injury by two mechanisms, p53-dependent apoptotic tissue repair in addition to well known DNA repair. Therefore, there are threshold doses below which there is no induction of teratogenic and carcinogenic effects after exposure to low-level radiation. (author)

  5. POSTRANSLATIONAL MODIFICATIONS OF P53: UPSTREAM SIGNALING PATHWAYS.

    Energy Technology Data Exchange (ETDEWEB)

    ANDERSON,C.W.APPELLA,E.

    2003-10-23

    The p53 tumor suppressor is a tetrameric transcription factor that is posttranslational modified at >20 different sites by phosphorylation, acetylation, or sumoylation in response to various cellular stress conditions. Specific posttranslational modifications, or groups of modifications, that result from the activation of different stress-induced signaling pathways are thought to modulate p53 activity to regulate cell fate by inducing cell cycle arrest, apoptosis, or cellular senescence. Here we review recent progress in characterizing the upstream signaling pathways whose activation in response to various genotoxic and non-genotoxic stresses result in p53 posttranslational modifications.

  6. Stochastic modeling of p53-regulated apoptosis upon radiation damage

    CERN Document Server

    Bhatt, Divesh; Bahar, Ivet

    2011-01-01

    We develop and study the evolution of a model of radiation induced apoptosis in cells using stochastic simulations, and identified key protein targets for effective mitigation of radiation damage. We identified several key proteins associated with cellular apoptosis using an extensive literature survey. In particular, we focus on the p53 transcription dependent and p53 transcription independent pathways for mitochondrial apoptosis. Our model reproduces known p53 oscillations following radiation damage. The key, experimentally testable hypotheses that we generate are - inhibition of PUMA is an effective strategy for mitigation of radiation damage if the treatment is administered immediately, at later stages following radiation damage, inhibition of tBid is more effective.

  7. The emerging role of p53 in exercise metabolism.

    Science.gov (United States)

    Bartlett, Jonathan D; Close, Graeme L; Drust, Barry; Morton, James P

    2014-03-01

    The major tumour suppressor protein, p53, is one of the most well-studied proteins in cell biology. Often referred to as the Guardian of the Genome, the list of known functions of p53 include regulatory roles in cell cycle arrest, apoptosis, angiogenesis, DNA repair and cell senescence. More recently, p53 has been implicated as a key molecular player regulating substrate metabolism and exercise-induced mitochondrial biogenesis in skeletal muscle. In this context, the study of p53 therefore has obvious implications for both human health and performance, given that impaired mitochondrial content and function is associated with the pathology of many metabolic disorders such as ageing, type 2 diabetes, obesity and cancer, as well as reduced exercise performance. Studies on p53 knockout (KO) mice collectively demonstrate that ablation of p53 content reduces intermyofibrillar (IMF) and subsarcolemmal (SS) mitochondrial yield, reduces cytochrome c oxidase (COX) activity and peroxisome proliferator-activated receptor gamma co-activator 1-α protein content whilst also reducing mitochondrial respiration and increasing reactive oxygen species production during state 3 respiration in IMF mitochondria. Additionally, p53 KO mice exhibit marked reductions in exercise capacity (in the magnitude of 50 %) during fatiguing swimming, treadmill running and electrical stimulation protocols. p53 may regulate contractile-induced increases in mitochondrial content via modulating mitochondrial transcription factor A (Tfam) content and/or activity, given that p53 KO mice display reduced skeletal muscle mitochondrial DNA, Tfam messenger RNA and protein levels. Furthermore, upon muscle contraction, p53 is phosphorylated on serine 15 and subsequently translocates to the mitochondria where it forms a complex with Tfam to modulate expression of mitochondrial-encoded subunits of the COX complex. In human skeletal muscle, the exercise-induced phosphorylation of p53(Ser15) is enhanced in conditions

  8. Resuscitation of wild-type p53 expression by disrupting ceramide glycosylation: a novel approach to target mutant p53 tumors

    OpenAIRE

    Liu, Yong-Yu

    2011-01-01

    Mutant p53 is frequently detected in cancers lose of its ability in tumor suppression and gain of function in promoting tumor progression. Restoration of p53 functions by replacement of wild-type p53 and inhibition of its degradation or increment of its transcriptional activity has been applied in prevention and treatment of cancers. Recent evidence indicates that disrupting ceramide glycosylation can resuscitate wild-type p53 expression and p53-dependent apoptosis in mutant p53 tumors. Actin...

  9. Dual Roles of MDM2 in the Regulation of p53: Ubiquitination Dependent and Ubiquitination Independent Mechanisms of MDM2 Repression of p53 Activity

    OpenAIRE

    Shi, Dingding; Gu, Wei

    2012-01-01

    MDM2 oncogenic protein is the principal cellular antagonist of the p53 tumor suppresser gene. p53 activity needs exquisite control to elicit appropriate responses to differential cellular stress conditions. p53 becomes stabilized and active upon various types of stresses. However, too much p53 is not beneficial to cells and causes lethality. At the steady state, p53 activity needs to be leashed for cell survival. Early studies suggested that the MDM2 oncoprotein negatively regulates p53 activ...

  10. SCGB3A2 Inhibits Acrolein-Induced Apoptosis through Decreased p53 Phosphorylation

    International Nuclear Information System (INIS)

    Chronic obstructive pulmonary disease (COPD), a major global health problem with increasing morbidity and mortality rates, is anticipated to become the third leading cause of death worldwide by 2020. COPD arises from exposure to cigarette smoke. Acrolein, which is contained in cigarette smoke, is the most important risk factor for COPD. It causes lung injury through altering apoptosis and causes inflammation by augmenting p53 phosphorylation and producing reactive oxygen species (ROS). Secretoglobin (SCGB) 3A2, a secretory protein predominantly present in the epithelial cells of the lungs and trachea, is a cytokine-like small molecule having anti-inflammatory, antifibrotic, and growth factor activities. In this study, the effect of SCGB3A2 on acrolein-related apoptosis was investigated using the mouse fibroblast cell line MLg as the first step in determining the possible therapeutic value of SCGB3A2 in COPD. Acrolein increased the production of ROS and phosphorylation of p53 and induced apoptosis in MLg cells. While the extent of ROS production induced by acrolein was not affected by SCGB3A2, p53 phosphorylation was significantly decreased by SCGB3A2. These results demonstrate that SCGB3A2 inhibited acrolein-induced apoptosis through decreased p53 phosphorylation, not altered ROS levels

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    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+/+ and p53+/- mice after irradiation at a young age. Methods and Materials: p53+/+ and p53+/- 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+/- 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.

  13. Biologic effect of exogenous wild p53 combined with irradiation on human melanoma cell lines with different p53 status

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of low dose irradiation on gene transfer efficiency and the effect of adenoviral-mediated exogenous P53 overexpression on apoptosis and radiosensitivity of radioresistant human melanoma cell lines A375(wild type p53)and WM983a(mutant type p53). Methods: Control vector, a replication deficient recombinant adenoviral vector containing a CMV promoter and green fluorescent protein (AdCMV-GFP), was used to transfect A375 cells and WM983a cells preirradiated with or without 1 Gy X-ray. The transduction efficiency of GFP gene was determined with fluorescence microscope directly. These two types of cells irradiated by 1 Gy X-ray were transfected with a replication deficient recombinant adenoviral vector carrying human wild p53 (AdCMV-p53), and mRNA level was detected by RT-PCR. The cell cycle delay and the expression of exogenous P53 were detected using flow cytometry (FCM) at different times after transfection. Tunel technique was used to detect cell apoptosis. The radiosensivity of A375 and WM983a cells after p53 transduction was analyzed by colony formation. Results: It is found that 1 Gy irradiation increased the gene transfection efficiency of A375 and WM983a cells. The expression of exogenous P53 was found to range from 60% to 80% among transfected cells during the first three days after transduction and then declined continuously down to the control level on day 10. G1 cell cycle arrest was also observed after p53 gene transduction. WM983a cells transfected with p53 showed higher sensitivity to X-ray-induced cell killing than A375 cells. Conclusions: It is indicated that low dose of ionizing radiation can improve gene transfection efficiency of A375 and WM983a cells mediated by adenovirus vector. Althrough the overexpresion of exogenous p53 may not inhibit cell growth and induce apoptosis of melanoma cell line A375 and WM983a irt vitro, the two cell lines are much more sensitive to cell death induced by irradiation. It is

  14. Mechanisms of p53-mediated mitochondrial membrane permeabilization

    Institute of Scientific and Technical Information of China (English)

    Eugenia Morselli; Lorenzo Galluzzi; Guido Kroemer

    2008-01-01

    @@ The p53 protein is mutated or inactivated in more than 50% of human cancers, underscoring its cardinal importance as an oncosuppressor, p53 is expressed in all nucleated cells and can be activated by a plethora of post-transcriptional modifications (in particular by the phosphorylation of critical serine residues), as well as by the inhibition of its degradation (mainly mediated by the E3 ubiquitin ligase MDM2).

  15. Targeting p53 for Novel Anticancer Therapy1

    OpenAIRE

    Wang, Zhen; Sun, Yi

    2010-01-01

    Carcinogenesis is a multistage process, involving oncogene activation and tumor suppressor gene inactivation as well as complex interactions between tumor and host tissues, leading ultimately to an aggressive metastatic phenotype. Among many genetic lesions, mutational inactivation of p53 tumor suppressor, the “guardian of the genome,” is the most frequent event found in 50% of human cancers. p53 plays a critical role in tumor suppression mainly by inducing growth arrest, apoptosis, and senes...

  16. p53 aerobics: the major tumor suppressor fuels your workout.

    Science.gov (United States)

    Kruse, Jan-Philipp; Gu, Wei

    2006-07-01

    In addition to its role as the central regulator of the cellular stress response, p53 can regulate aerobic respiration via the novel transcriptional target SCO2, a critical regulator of the cytochrome c oxidase complex (Matoba et al., 2006). Loss of p53 results in decreased oxygen consumption and aerobic respiration and promotes a switch to glycolysis, thereby reducing endurance during physical exercise. PMID:16814724

  17. UHRF2, another E3 ubiquitin ligase for p53

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Lu; Wang, Xiaohui; Jin, Fangmin; Yang, Yan; Qian, Guanhua [Department of Cell Biology and Medical Genetics, Chongqing Medical University, Chongqing (China); Duan, Changzhu, E-mail: duanchzhu@cqmu.edu.cn [Key Laboratory of Clinical Laboratory Diagnostics of Ministry of Education, Faculty of Laboratory Medicine, Chongqing Medical University, Chongqing (China); Department of Cell Biology and Medical Genetics, Chongqing Medical University, Chongqing (China)

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer UHRF2 associates with p53 in vivo and in vitro. Black-Right-Pointing-Pointer UHRF2 interacts with p53 through its SRA/YDG domain. Black-Right-Pointing-Pointer UHRF2 ubiquitinates p53 in vivo and in vitro. -- Abstract: UHRF2, ubiquitin-like with PHD and ring finger domains 2, is a nuclear E3 ubiquitin ligase, which is involved in cell cycle and epigenetic regulation. UHRF2 interacts with multiple cell cycle proteins, including cyclins (A2, B1, D1, and E1), CDK2, and pRb; moreover, UHRF2 could ubiquitinate cyclin D1 and cyclin E1. Also, UHRF2 has been shown to be implicated in epigenetic regulation by associating with DNMTs, G9a, HDAC1, H3K9me2/3 and hemi-methylated DNA. We found that UHRF2 associates with tumor suppressor protein p53, and p53 is ubiquitinated by UHRF2 in vivo and in vitro. Given that both UHRF2 and p53 are involved in cell cycle regulation, this study may suggest a novel signaling pathway on cell proliferation.

  18. Expression of p53 protein in pituitary adenomas

    Directory of Open Access Journals (Sweden)

    Oliveira M.C.

    2002-01-01

    Full Text Available Inactivating mutations of TP53, a tumor suppressor gene, are associated with abnormal cell proliferation. Although p53 expression is common in many human malignancies, p53 protein has seldom been evaluated in pituitary tumors. When detected, the percentage of p53-positive cells is low, and, in general, it is exclusive for invasive lesions. The aim of the present study was to use immunohistochemistry to determine the presence of p53 protein in pituitary adenomas from tumor samples of 163 surgeries performed in 148 patients (40% male, 60% female. In 35% of the cases the adenoma was nonfunctional, while in the others it was associated with PRL, GH and/or ACTH endocrine hypersecretion syndrome. Macroadenomas were observed in 83.2% of the cases with available neuroimage evaluation, of which 28% invaded the cavernous, sphenoid and/or ethmoidal sinus, bone, third ventricle or subfrontal lobe. p53 protein was detected in 2/148 patients (1.3%. Immunohistochemistry was positive for PRL and GH in these cases. Due to the high percentage of invasive pituitary adenomas found in our study, the low frequency of p53 detection suggests that it is inadequate as a routine marker for aggressiveness and as a predictive factor of tumor behavior.

  19. Estradiol induces functional inactivation of p53 by intracellular redistribution.

    Science.gov (United States)

    Molinari, A M; Bontempo, P; Schiavone, E M; Tortora, V; Verdicchio, M A; Napolitano, M; Nola, E; Moncharmont, B; Medici, N; Nigro, V; Armetta, I; Abbondanza, C; Puca, G A

    2000-05-15

    Estrogen treatment of MCF-7 cells grown in serum-free medium induced a modification of the intracellular distribution of p53 protein. Western blot analysis and immunofluorescence staining showed that p53 was localized in the nucleus of untreated cell and that after 48 h of hormone treatment, it was mostly localized in the cytoplasm. This effect was blocked by the antiestrogen ICI182,780. Intracellular redistribution of p53 was correlated to a reduced expression of the WAF1/CIP1 gene product and to the presence of degradation fragments of p53 in the cytosol. Estradiol treatment prevented the growth inhibition induced by oligonucleotide transfection, simulating DNA damage. This observation indicated that the wild-type p53 gene product present in the MCF-7 cell could be inactivated by estradiol through nuclear exclusion to permit the cyclin-dependent phosphorylation events leading to the G1-S transition. In addition, the estradiol-induced inactivation of p53 could be involved in the tumorigenesis of estrogen-dependent neoplasm. PMID:10825127

  20. P53 in human melanoma fails to regulate target genes associated with apoptosis and the cell cycle and may contribute to proliferation

    International Nuclear Information System (INIS)

    Metastatic melanoma represents a major clinical problem. Its incidence continues to rise in western countries and there are currently no curative treatments. While mutation of the P53 tumour suppressor gene is a common feature of many types of cancer, mutational inactivation of P53 in melanoma is uncommon; however, its function often appears abnormal. In this study whole genome bead arrays were used to examine the transcript expression of P53 target genes in extracts from 82 melanoma metastases and 6 melanoma cell lines, to provide a global assessment of aberrant P53 function. The expression of these genes was also examined in extracts derived from diploid human melanocytes and fibroblasts. The results indicated that P53 target transcripts involved in apoptosis were under-expressed in melanoma metastases and melanoma cell lines, while those involved in the cell cycle were over-expressed in melanoma cell lines. There was little difference in the transcript expression of P53 target genes between cell lines with null/mutant P53 compared to those with wild-type P53, suggesting that altered expression in melanoma was not related to P53 status. Similarly, down-regulation of P53 by short-hairpin RNA (shRNA) had limited effect on P53 target gene expression in melanoma cells, whereas there were a large number of P53 target genes whose mRNA expression was significantly altered by P53 inhibition in melanocytes. Analysis of whole genome gene expression profiles indicated that the ability of P53 to regulate genes involved in the cell cycle was significantly reduced in melanoma cells. Moreover, inhibition of P53 in melanocytes induced changes in gene expression profiles that were characteristic of melanoma cells and resulted in increased proliferation. Conversely, knockdown of P53 in melanoma cells resulted in decreased proliferation. These results indicate that P53 target genes involved in apoptosis and cell cycle regulation are aberrantly expressed in melanoma and that this

  1. Xenogeneic human p53 DNA vaccination by electroporation breaks immune tolerance to control murine tumors expressing mouse p53.

    Directory of Open Access Journals (Sweden)

    Ruey-Shyang Soong

    Full Text Available The pivotal role of p53 as a tumor suppressor protein is illustrated by the fact that this protein is found mutated in more than 50% of human cancers. In most cases, mutations in p53 greatly increase the otherwise short half-life of this protein in normal tissue and cause it to accumulate in the cytoplasm of tumors. The overexpression of mutated p53 in tumor cells makes p53 a potentially desirable target for the development of cancer immunotherapy. However, p53 protein represents an endogenous tumor-associated antigen (TAA. Immunization against a self-antigen is challenging because an antigen-specific immune response likely generates only low affinity antigen-specific CD8(+ T-cells. This represents a bottleneck of tumor immunotherapy when targeting endogenous TAAs expressed by tumors. The objective of the current study is to develop a safe cancer immunotherapy using a naked DNA vaccine. The vaccine employs a xenogeneic p53 gene to break immune tolerance resulting in a potent therapeutic antitumor effect against tumors expressing mutated p53. Our study assessed the therapeutic antitumor effect after immunization with DNA encoding human p53 (hp53 or mouse p53 (mp53. Mice immunized with xenogeneic full length hp53 DNA plasmid intramuscularly followed by electroporation were protected against challenge with murine colon cancer MC38 while those immunized with mp53 DNA were not. In a therapeutic model, established MC38 tumors were also well controlled by treatment with hp53 DNA therapy in tumor bearing mice compared to mp53 DNA. Mice vaccinated with hp53 DNA plasmid also exhibited an increase in mp53-specific CD8(+ T-cell precursors compared to vaccination with mp53 DNA. Antibody depletion experiments also demonstrated that CD8(+ T-cells play crucial roles in the antitumor effects. This study showed intramuscular vaccination with xenogeneic p53 DNA vaccine followed by electroporation is capable of inducing potent antitumor effects against tumors

  2. Abnormalities of the ARF-p53 pathway in primary angiosarcomas of the liver.

    Science.gov (United States)

    Weihrauch, Markus; Markwarth, Anett; Lehnert, Gerhard; Wittekind, Christian; Wrbitzky, Renate; Tannapfel, Andrea

    2002-09-01

    The INK4a-ARF locus, located on chromosome 9p21, encodes 2 cell cycle-regulatory proteins, p16(INKa) and p14(ARF), acting through the Rb-CDK4 and p53 pathways. This study was done to investigate the contribution of the INK4a-ARF locus in tumorigenesis of angiosarcoma of the liver. Alterations of p14(ARF), p16(INKa), and p53 in primary liver angiosarcoma from 19 patients were analyzed by methylation-specific polymerase chain reaction (MSP), restriction enzyme-related polymerase chain reaction (RE-PCR), microsatellite analysis, and DNA sequencing. As a control group, 12 angiosarcomas from other organs were analyzed. Promoter methylation of p14(ARF) was found in 5 of 19 cases (26%), and p16(INKa) showed aberrant promoter methylation in 12 of 19 cases (63%). One tumor (5%) had homozygous deletion of the INK4a-ARF locus. Methylation and deletion correlated with loss of mRNA transcription. Methylated p14(ARF) appeared in the context of a methylated p16(INKa) promoter in 3 cases of the 5 angiosarcomas methylated at p14(ARF). p14(ARF) aberrant methylation was not related to the presence of p53 mutations, which was detected in 6 of 19 (32%) cases. Alterations of the INK4a-ARF locus or p53 as were not established independent prognostic factors in these tumors. In conclusion, our data indicate that the INK4a-ARF locus is frequently inactivated in angiosarcoma of the liver and occurs independently of p53 mutations. PMID:12378512

  3. DNA damage induces phosphorylation of the amino terminus of p53

    OpenAIRE

    Siliciano, Janet D.; Canman, Christine E.; Taya, Yoichi; Sakaguchi, Kazuyasu; Appella, Ettore; Kastan, Michael B.

    1997-01-01

    Data are presented demonstrating that DNA damage leads to specific post-translational modifications of p53 protein. Using two-dimensional peptide mapping of in vivo radiolabeled p53 tryptic phosphopeptides, recombinant truncated p53 protein, and synthetic p53 tryptic peptides, a unique p53 phosphopeptide was identified after exposure of ML-1 cells to ionizing irradiation. This peptide represents the first 24 amino acids of p53 and contains three phosphorylated serine residues. A specific p53 ...

  4. Association of p53 codon 72 polymorphism with liver metastases of colorectal cancers positive for p53 overexpression

    Institute of Scientific and Technical Information of China (English)

    Zhong-zheng ZHU; Bing LIU; Ai-zhong WANG; Hang-ruo JIA; Xia-xiang JIN; Xiang-lei HE; Li-fang HOU; Guan-shan ZHU

    2008-01-01

    Objective: To evaluate the association between p53 codon 72 polymorphism (R72P) and the risk of colorectal liver metastases. Methods: The p53 R72P genotype was identified by polymerase chain reaction-restriction fi'agment length poly-morphism (PCR-RFLP) method in 78 consecutive colorectal cancer patients with liver metastases and 214 age- and sex-matched cases with nonmetastatic colorectai cancer. Results: The R allele of the p53 R72P polymorphism was more frequently found in metastatic cases than in nonmetastatic cases (P=0.075). Carriers of the 72R allele had a 2.25-fold (95% CI (confidence inter-val)=1.05~4.83) increased risk of liver metastases. On the stratification analysis, 72R-carrying genotype conferred a 3.46-fold (95% CI=1.02~11.72) and a 1.05-fold (95% CI=0.36~3.08) increased risk of liver metastases for p53 overexpression-positive and negative colorectal cancers, respectively. Conclusion: These results demonstrate for the first time that the 72R allele of the p53 polymorphism has an increased risk for liver metastases in colorectal cancers positive for p53 overexpression.

  5. A surrogate p53 reporter in Drosophila reveals the interaction of eIF4E and p53

    International Nuclear Information System (INIS)

    eIF4E promotes translation upon binding the mRNA 5'cap and it is required for cell proliferation. p53 is a proapoptotic protein which is activated in response to DNA damage. There is evidence that suggests that eIF4E and p53 are connected in a mechanism that regulates their function. We propose a model for that such a mechanism to explain the equilibrium between apoptosis and cell proliferation. Our data shows a correlation between the overexpression of eIF4E and the suppression of apoptosis triggered by the overexpression of p53 in Drosophila imaginal discs. We also studied a reporter transgene which expresses GFP in response to p53 activation by gamma radiation. We could confirm that this p53 surrogate works in imaginal discs as well as in embryos. This provided us a tool to quantify the effect on the GFP signal by overexpression of eIF4E to confirm how these two proteins could interact in vivo. Our results suggest that p53 and eIF4E are indeed in an equilibrium that decides if a cell shall proliferate or die. (authors)

  6. Mutant p53 - heat shock response oncogenic cooperation: a new mechanism of cancer cell survival

    Directory of Open Access Journals (Sweden)

    Evguenia eAlexandrova

    2015-04-01

    Full Text Available The main tumor suppressor function of p53 as a ‘guardian of the genome’ is to respond to cellular stress by transcriptional activation of apoptosis, growth arrest or senescence in damaged cells. Not surprisingly, mutations in the p53 gene are the most frequent genetic alteration in human cancers. Importantly, mutant p53 (mutp53 proteins not only lose their wild-type tumor suppressor activity, but also can actively promote tumor development. Two main mechanisms accounting for mutp53 proto-oncogenic activity are inhibition of the wild-type p53 in a dominant-negative fashion and gain of additional oncogenic activities known as gain-of-function (GOF. Here we discuss a novel mechanism of mutp53 GOF, which relies on its oncogenic cooperation with the heat shock machinery. This coordinated adaptive mechanism renders cancer cells more resistant to proteotoxic stress and provides both, a strong survival advantage to cancer cells and a promising means for therapeutic intervention.

  7. Involvement of human ribosomal proteins in nucleolar structure and p53-dependent nucleolar stress.

    Science.gov (United States)

    Nicolas, Emilien; Parisot, Pascaline; Pinto-Monteiro, Celina; de Walque, Roxane; De Vleeschouwer, Christophe; Lafontaine, Denis L J

    2016-01-01

    The nucleolus is a potent disease biomarker and a target in cancer therapy. Ribosome biogenesis is initiated in the nucleolus where most ribosomal (r-) proteins assemble onto precursor rRNAs. Here we systematically investigate how depletion of each of the 80 human r-proteins affects nucleolar structure, pre-rRNA processing, mature rRNA accumulation and p53 steady-state level. We developed an image-processing programme for qualitative and quantitative discrimination of normal from altered nucleolar morphology. Remarkably, we find that uL5 (formerly RPL11) and uL18 (RPL5) are the strongest contributors to nucleolar integrity. Together with the 5S rRNA, they form the late-assembling central protuberance on mature 60S subunits, and act as an Hdm2 trap and p53 stabilizer. Other major contributors to p53 homeostasis are also strictly late-assembling large subunit r-proteins essential to nucleolar structure. The identification of the r-proteins that specifically contribute to maintaining nucleolar structure and p53 steady-state level provides insights into fundamental aspects of cell and cancer biology. PMID:27265389

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

    International Nuclear Information System (INIS)

    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·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

  9. Small Molecule Modulator of p53 Signaling Pathway: Application for Radiosensitizing or Radioprotection Agents

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Sang Taek; Cho, Mun Ju; Gwak, Jung Sug; Ryu, Min Jung [PharmacoGenomics Research Center, Inje University, Busan (Korea, Republic of); Song, Jie Young; Yun, Yeon Sook [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2009-05-15

    The tumor suppressor p53 is key molecule to protect the cell against genotoxic stress and..the most frequently mutated..protein..in cancer cells. Lack of functional p53..is accompanied by high rate of genomic instability, rapid tumor progression, resistance to anticancer therapy, and increased angiogenesis. In response to DNA damage, p53 protein rapidly accumulated through attenuated proteolysis and is also activated as transcription factor. Activated p53 up-regulates target genes involved in cell cycle arrest and/or apoptosis and then lead to suppression of malignant transformation and the maintenance of genomic integrity. Chemical genetics is a new technology to uncover the signaling networks that regulated biological phenotype using exogenous reagents such as small molecules. Analogous to classical forward genetic screens in model organism, this approach makes use of high throughput, phenotypic assay to identify small molecules that disrupt gene product function in a way that alters a phenotype of interest. Recently, interesting small molecules were identified from cell based high throughput screening and its target protein or mechanism of action were identified by various methods including affinity chromatography, protein array profiling, mRNA or phage display, transcription profiling, and RNA interference.

  10. Involvement of human ribosomal proteins in nucleolar structure and p53-dependent nucleolar stress

    Science.gov (United States)

    Nicolas, Emilien; Parisot, Pascaline; Pinto-Monteiro, Celina; de Walque, Roxane; De Vleeschouwer, Christophe; Lafontaine, Denis L. J.

    2016-01-01

    The nucleolus is a potent disease biomarker and a target in cancer therapy. Ribosome biogenesis is initiated in the nucleolus where most ribosomal (r-) proteins assemble onto precursor rRNAs. Here we systematically investigate how depletion of each of the 80 human r-proteins affects nucleolar structure, pre-rRNA processing, mature rRNA accumulation and p53 steady-state level. We developed an image-processing programme for qualitative and quantitative discrimination of normal from altered nucleolar morphology. Remarkably, we find that uL5 (formerly RPL11) and uL18 (RPL5) are the strongest contributors to nucleolar integrity. Together with the 5S rRNA, they form the late-assembling central protuberance on mature 60S subunits, and act as an Hdm2 trap and p53 stabilizer. Other major contributors to p53 homeostasis are also strictly late-assembling large subunit r-proteins essential to nucleolar structure. The identification of the r-proteins that specifically contribute to maintaining nucleolar structure and p53 steady-state level provides insights into fundamental aspects of cell and cancer biology. PMID:27265389

  11. Crosstalk of EDA-A2/XEDAR in the p53 signaling pathway.

    Science.gov (United States)

    Tanikawa, Chizu; Ri, Cui; Kumar, Vinod; Nakamura, Yusuke; Matsuda, Koichi

    2010-06-01

    We recently identified X-linked ectodermal dysplasia receptor (XEDAR, also known as TNFRSF27 or EDA2R) as a direct p53 target that was frequently downregulated in colorectal cancer tissues due to its epigenetic alterations or through the p53 gene mutations. However, the role of the posttranslational regulation of XEDAR protein in colorectal carcinogenesis was not well clarified thus far. Here, we report that the extracellular NH(2) terminus of XEDAR protein was cleaved by a metalloproteinase and released into culture media. The remaining COOH-terminal membrane-anchored fragment was rapidly degraded through the ubiquitin-proteasome pathway. Interestingly, ectopic p53 expression also transactivated an XEDAR ligand, EDA-A2, together with XEDAR. Moreover, EDA-A2 blocked the cleavage of XEDAR and subsequently inhibited cell growth. We also found a missense mutation of the XEDAR gene in NCI-H716 colorectal cancer cells, which caused the translocation of XEDAR protein from cell membrane to cytoplasm. This mutation attenuated the growth-suppressive effect of XEDAR, indicating that membrane localization is critical for physiologic XEDAR function. Thus, our findings clearly revealed the crucial role of EDA-A2/XEDAR interaction in the p53-signaling pathway. PMID:20501644

  12. Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly.

    Science.gov (United States)

    Mao, Hanqian; McMahon, John J; Tsai, Yi-Hsuan; Wang, Zefeng; Silver, Debra L

    2016-09-01

    The exon junction complex (EJC) is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling. Using a new conditional allele, we first show that Eif4a3 haploinsufficiency phenocopies aberrant neurogenesis and microcephaly of Magoh and Rbm8a mutant mice. Transcriptomic and proteomic analyses of embryonic brains at the onset of neurogenesis identifies common pathways altered in each of the 3 EJC mutants, including ribosome, proteasome, and p53 signaling components. We further demonstrate all 3 mutants exhibit defective splicing of RNA regulatory proteins, implying an EJC dependent RNA regulatory network that fine-tunes gene expression. Finally, we show that genetic ablation of one downstream pathway, p53, significantly rescues microcephaly of all 3 EJC mutants. This implicates p53 activation as a major node of neurodevelopmental pathogenesis following EJC impairment. Altogether our study reveals new mechanisms to help explain how EJC mutations influence neurogenesis and underlie neurodevelopmental disease. PMID:27618312

  13. miR-605 joins p53 network to form a p53:miR-605:Mdm2 positive feedback loop in response to stress

    OpenAIRE

    Xiao, Jiening; Lin, Huixian; Luo, Xiaobin; Luo, Xiaoyan; Wang, Zhiguo

    2011-01-01

    Mdm2, a transcriptional target of p53, promotes p53 degradation in a well-established negative feedback loop. Here, microRNA miR-605 is found to break this loop: being induced by p53 in response to stress, and downregulating Mdm2 to promote robust p53 expression.

  14. The p53 gene as a modifier of intrinsic radiosensitivity: implications for radiotherapy

    International Nuclear Information System (INIS)

    Background and purpose: Experimental studies have implicated the normal or 'wild type' p53 protein (i.e. WTp53) in the cellular response to ionizing radiation and other DNA damaging agents. Whether altered WTp53 protein function can lead to changes in cellular radiosensitivity and/or clinical radiocurability remains an area of ongoing study. In this review, we describe the potential implications of altered WTp53 protein function in normal and tumour cells as it relates to clinical radiotherapy, and describe novel treatment strategies designed to re-institute WTp53 protein function as a means of sensitizing cells to ionizing radiation. Methods and Materials: A number of experimental and clinical studies are critically reviewed with respect to the role of the p53 protein as a determinant of cellular oncogenesis, genomic stability, apoptosis, DNA repair and radioresponse in normal and transformed mammalian cells. Results: In normal fibroblasts, exposure to ionizing radiation leads to a G1 cell cycle delay (i.e. a 'G1 checkpoint') as a result of WTp53-mediated inhibition of G1-cyclin-kinase and retinoblastoma (pRb) protein function. The G1 checkpoint response is absent in tumour cells which express a mutant form of the p53 protein (i.e. MTp53), leading to acquired radioresistance in vitro. Depending on the cell type studied, this increase in cellular radiation survival can be mediated through decreased radiation-induced apoptosis, or altered kinetics of the radiation-induced G1 checkpoint. Recent biochemical studies support an indirect role for the p53 protein in both nucleotide excision and recombinational DNA repair pathways. However, based on clinicopathologic data, it remains unclear as to whether WTp53 protein function can predict for human tumour radiocurability and normal tissue radioresponse. Conclusions: Alterations in cell cycle control secondary to aberrant WTp53 protein function may be clinically significant if they lead to the acquisition of mutant

  15. P53 GENE MUTATIONS IN NON-SMALL CELL LUNG CANCER DETECTED BY POLYMERASE CHAIN REACTION SINGLE-STRAND CONFORMATION POLYMORPHISM ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    @@ Mutations of the p53 tumor suppressor gene are the most frequent genetic alterations detected in human lung cancer. To assess the pathogenic significance of p53 gene alterations in Chinese non-small cell lung cancer(NSCLC),74 paired samples of primary lung cancer and normal lung tissue far away from the cancer were analyzed for mutations of the p53 gene(exons 5-8) using exon-specific PCR, single-strand conformation polymorphism (PCR-SSCP). p53 mutations were observed in 55.4%(41/74) of the samples. No linkages were detected between the incidence of p53 mutations and histological type, lymph node metastasis,age or sex. Significant association between p53 mutations and degree of differentiation in adenocarcinomas, not in squamous cell carcinomas, was observed. The frequency of p53 mutations in smokers(65.3%) was higher than in nonsmokers(33.3%) and reached statistical significance.We also found p53 mutations in 6/7 samples which had tissue invasion and distant metastasis.These results suggest that smoking could be an important factor in lung carcinogenesis,p53 mutation is a worse prognosis indicator in adenocarcinomas and related to high aggressive behavior of human lung cancer.

  16. Involvement of human ribosomal proteins in nucleolar structure and p53-dependent nucleolar stress

    OpenAIRE

    Nicolas, Emilien; Parisot, Pascaline; Pinto-Monteiro, Celina; de Walque, Roxane; De Vleeschouwer, Christophe; Lafontaine, Denis L. J.

    2016-01-01

    The nucleolus is a potent disease biomarker and a target in cancer therapy. Ribosome biogenesis is initiated in the nucleolus where most ribosomal (r-) proteins assemble onto precursor rRNAs. Here we systematically investigate how depletion of each of the 80 human r-proteins affects nucleolar structure, pre-rRNA processing, mature rRNA accumulation and p53 steady-state level. We developed an image-processing programme for qualitative and quantitative discrimination of normal from altered nucl...

  17. Modulation of p53β and p53γ expression by regulating the alternative splicing of TP53 gene modifies cellular response.

    Science.gov (United States)

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

    2014-09-01

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

  18. Suppression of Id2, a member of the inhibitor of differentiation family and a target of mutant p53, is required for mutant p53 gain of function

    OpenAIRE

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

    2008-01-01

    Over-expression 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 SW480 colon cancer cell line, which contains mutant p53(R273H/P309S), and 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 p5...

  19. EXPRESSION OF p16 AND p53 IN GASTRIC CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Objective:To investigate the clinical significance of p53 and p16 expression in gastric carcinoma with special reference to the prognosis.Methods:One hundred and fifty-two patients with gastric carcinoma undergoing operation in our hospital between 1991 and 1998 were evaluated for expression of p53 and p16 in formalin-fixed and paraffin-embedded tumor tissue utilizing Avidin-Biotin immunohistochemistry techniques. Statistical correlations with stage, histological type, differentiation degree, location, size, and overall survival were done. The Cox proportional hazard model was also performed to evaluate which factors had an independent prognostic value.Results:In 152 cases of resected gastric cancer, 110 (72.4%) were p16 positive and 49 (32.2%) showed p53 overexpression. Differences were observed in the frequency of p16 positivity with respect to age, gender and tumor size. The frequency of p53 positivity cells in well-differentiated tumors was significantly higher than that in poorly differentiated tumors (41.9% vs. 25.6%; P= 0.034). In a multivariate analysis, tumor TNM stage, perioperation chemotherapy and the expression of p16 were independent prognostic factors in gastric cancer.Conclusions:The results of the current study suggest that expression of p16 may be a useful prognostic factor for patients with gastric carcinoma, but the expression of p53 as detected by immunohistochemistry were of no value in predicting the prognosis of patients with gastric carcinoma independently.

  20. Sequence-dependent sliding kinetics of p53

    Science.gov (United States)

    Leith, Jason; Tafvizi, Anahita; Huang, Fang; Uspal, William; Doyle, Patrick; Fersht, Alan; Mirny, Leonid; van Oijen, Antoine

    2012-02-01

    Theoretical work has long proposed that one-dimensional sliding along DNA while simultaneously reading its sequence can accelerate transcription factors' (TFs) search for their target sites. More recently, functional sliding has been shown to require TFs to possess at least two DNA-binding modes. The tumor suppressor p53 has been directly observed to slide on DNA, and structural and single-molecule studies have provided evidence for a two-mode model for the protein. If the model is in fact applicable to p53, then the requirement that TFs read while they slide implies that p53's mobility on DNA should be affected by non-cognate sites and thus that its diffusivity should be generally sequence-dependent. Here we confirm this prediction with single-molecule microscopy measurements of p53's local diffusivity on non-cognate DNA. We show how a two-mode model accurately predicts the variation in local diffusivity while a single-mode model does not. Our work provides evidence that p53's sliding is indeed functional and suggests that the timing and efficiency of its activating and repressing transcription can depend on its non-cognate binding properties and its ability to change between multiple modes of binding, in addition to the much better-studied effects of cognate-site binding.

  1. p53 Prevents Entry into Mitosis with Uncapped Telomeres

    Science.gov (United States)

    Thanasoula, Maria; Escandell, Jose Miguel; Martinez, Paula; Badie, Sophie; Muñoz, Purificacion; Blasco, María A.; Tarsounas, Madalena

    2016-01-01

    Summary Telomeres are protected by capping structures consisting of core protein complexes that bind with sequence specificity to telomeric DNA (reviewed in [1]). In their absence, telomeres trigger a DNA damage response, materialized in accumulation at the telomere of damage response proteins, e.g., phosphorylated histone H2AX (γH2AX), into telomere-dysfunction-induced foci [2, 3]. Telomere uncapping occurs transiently in every cell cycle in G2 [4], following DNA replication, but little is known about how protective structures are reassembled or whether this process is controlled by the cell-cycle surveillance machinery. Here, we report that telomere capping is monitored at the G2/M transition by the p53/p21 damage response pathway. Unlike their wild-type counterparts, human and mouse cells lacking p53 or p21 progress into mitosis prematurely with persisting uncapped telomeres. Furthermore, artificially uncapped telomeres delay mitotic entry in a p53- and p21-dependent manner. Uncapped telomeres that persist in mitotic p53-deficient cells are shorter than average and religate to generate end-to-end fusions. These results suggest that a p53-dependent pathway monitors telomere capping after DNA replication and delays G2/M progression in the presence of unprotected telomeres. This mechanism maintains a cell-cycle stage conducive for capping reactions and prevents progression into stages during which uncapped telomeres are prone to deleterious end fusions. PMID:20226664

  2. Activation of endogenous p53 by combined p19Arf gene transfer and nutlin-3 drug treatment modalities in the murine cell lines B16 and C6

    International Nuclear Information System (INIS)

    Reactivation of p53 by either gene transfer or pharmacologic approaches may compensate for loss of p19Arf or excess mdm2 expression, common events in melanoma and glioma. In our previous work, we constructed the pCLPG retroviral vector where transgene expression is controlled by p53 through a p53-responsive promoter. The use of this vector to introduce p19Arf into tumor cells that harbor p53wt should yield viral expression of p19Arf which, in turn, would activate the endogenous p53 and result in enhanced vector expression and tumor suppression. Since nutlin-3 can activate p53 by blocking its interaction with mdm2, we explored the possibility that the combination of p19Arf gene transfer and nutlin-3 drug treatment may provide an additive benefit in stimulating p53 function. B16 (mouse melanoma) and C6 (rat glioma) cell lines, which harbor p53wt, were transduced with pCLPGp19 and these were additionally treated with nutlin-3 or the DNA damaging agent, doxorubicin. Viral expression was confirmed by Western, Northern and immunofluorescence assays. p53 function was assessed by reporter gene activity provided by a p53-responsive construct. Alterations in proliferation and viability were measured by colony formation, growth curve, cell cycle and MTT assays. In an animal model, B16 cells were treated with the pCLPGp19 virus and/or drugs before subcutaneous injection in C57BL/6 mice, observation of tumor progression and histopathologic analyses. Here we show that the functional activation of endogenous p53wt in B16 was particularly challenging, but accomplished when combined gene transfer and drug treatments were applied, resulting in increased transactivation by p53, marked cell cycle alteration and reduced viability in culture. In an animal model, B16 cells treated with both p19Arf and nutlin-3 yielded increased necrosis and decreased BrdU marking. In comparison, C6 cells were quite susceptible to either treatment, yet p53 was further activated by the combination of p19

  3. 胃癌患者血清P53蛋白与抗体检测的比较%Detection of serum P53 protein and P53 antibody in patients with gastric carcinoma*

    Institute of Scientific and Technical Information of China (English)

    刘辉琦; 刘慧; 刘杰; 王生兰

    2011-01-01

    目的 比较胃癌患者血清P53蛋白与抗体检测的敏感性.方法 采用间接ELISA法检测胃癌患者血清P53抗体,夹心ELISA法检测胃癌患者血清P53蛋白.结果 胃癌患者血清P53蛋白阳性率为14.0%,抗体阳性率为32.0%,二者差异有统计学意义(P<0.05).结论 胃癌患者血清P53抗体的检测比P53蛋白的检测更敏感.%Objective To compare the detection sensitivity of serum P53 protein and P53 antibody in patients with gastric carci noma. Methods Indirect ELISA was adopted to detect serum P53 antibody,and double antibodies sandwich ELISA technique was used to measure serum P53 protein. Results The positive rates of serum P53 protein and P53 antibody were 14.0% and 32.0% re spectively,which were with significant difference. Conclusion P53 antibody detection could be more sensitive than P53 protein in patients with gastric carcinoma.

  4. Mdm2’s Dilemma: To Degrade or To Translate p53?

    OpenAIRE

    Hamard, Pierre-Jacques; Manfredi, James J

    2012-01-01

    In this issue of Cancer Cell, Gajjar et al. provide insight into how Mdm2 can both inhibit and enhance p53 activity. In the basal setting, Mdm2 binds p53 and promotes p53 degradation. Under stress conditions, ATM-dependent phosphorylation of Mdm2 results in its recruitment to p53 mRNA, thereby stimulating p53 translation.

  5. L-GILZ binds p53 and MDM2 and suppresses tumor growth through p53 activation in human cancer cells

    OpenAIRE

    Ayroldi, E; Petrillo, M G; Bastianelli, A; Marchetti, M C; Ronchetti, S; Nocentini, G; Ricciotti, L; Cannarile, L; Riccardi, C

    2014-01-01

    The transcription factor p53 regulates the expression of genes crucial for biological processes such as cell proliferation, metabolism, cell repair, senescence and apoptosis. Activation of p53 also suppresses neoplastic transformations, thereby inhibiting the growth of mutated and/or damaged cells. p53-binding proteins, such as mouse double minute 2 homolog (MDM2), inhibit p53 activation and thus regulate p53-mediated stress responses. Here, we found that long glucocorticoid-induced leucine z...

  6. IGF-I enhances cellular senescence via the reactive oxygen species-p53 pathway

    Energy Technology Data Exchange (ETDEWEB)

    Handayaningsih, Anastasia-Evi; Takahashi, Michiko; Fukuoka, Hidenori; Iguchi, Genzo; Nishizawa, Hitoshi; Yamamoto, Masaaki; Suda, Kentaro [Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Takahashi, Yutaka, E-mail: takahash@med.kobe-u.ac.jp [Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Cellular senescence plays an important role in tumorigenesis and aging process. Black-Right-Pointing-Pointer We demonstrated IGF-I enhanced cellular senescence in primary confluent cells. Black-Right-Pointing-Pointer IGF-I enhanced cellular senescence in the ROS and p53-dependent manner. Black-Right-Pointing-Pointer These results may explain the underlying mechanisms of IGF-I involvement in tumorigenesis and in regulation of aging. -- Abstract: Cellular senescence is characterized by growth arrest, enlarged and flattened cell morphology, the expression of senescence-associated {beta}-galactosidase (SA-{beta}-gal), and by activation of tumor suppressor networks. Insulin-like growth factor-I (IGF-I) plays a critical role in cellular growth, proliferation, tumorigenesis, and regulation of aging. In the present study, we show that IGF-I enhances cellular senescence in mouse, rat, and human primary cells in the confluent state. IGF-I induced expression of a DNA damage marker, {gamma}H2AX, the increased levels of p53 and p21 proteins, and activated SA-{beta}-gal. In the confluent state, an altered downstream signaling of IGF-I receptor was observed. Treatment with a reactive oxygen species (ROS) scavenger, N-acetylcystein (NAC) significantly suppressed induction of these markers, indicating that ROS are involved in the induction of cellular senescence by IGF-I. In p53-null mouse embryonic fibroblasts, the IGF-I-induced augmentation of SA-{beta}-gal and p21 was inhibited, demonstrating that p53 is required for cellular senescence induced by IGF-I. Thus, these data reveal a novel pathway whereby IGF-I enhances cellular senescence in the ROS and p53-dependent manner and may explain the underlying mechanisms of IGF-I involvement in tumorigenesis and in regulation of aging.

  7. Proliferating cell nuclear antigen, p53 and micro vessel density: Grade II vs. Grade III astrocytoma

    Directory of Open Access Journals (Sweden)

    Malhan Priya

    2010-01-01

    Full Text Available Histological classification and grading are prime procedures in the management of patients with astrocytoma, providing vital data for therapeutic decision making and prognostication. However, it has limitations in assessing biological tumor behavior. This can be overcome by using newer immunohistochemical techniques. This study was carried out to compare proliferative indices using proliferating cell nuclear antigen (PCNA, extent of p53 expression and micro vessel morphometric parameters in patients with low grade and anaplastic astrocytoma. Twenty-five patients, each of grade II and grade III astrocytoma were evaluated using monoclonal antibodies to PCNA, p53 protein and factor VIII related antigen. PCNA, p53-labeling indices were calculated along with micro vessel morphometric analysis using Biovis Image plus Software. Patients with grade III astrocytoma had higher PCNA and p53 labeling indices as compared with grade II astrocytoma (29.14 plus/minus 9.87% vs. 16.84 plus/minus 6.57%, p 0.001; 18.18 plus/minus 6.14% vs. 6.14 plus/minus 7.23%, p 0.001, respectively. Micro vessel percentage area of patients with grade III astrocytoma was also (4.26 plus/minus 3.70 vs. 1.05 plus/minus 0.56, p 0.001, higher along with other micro vessel morphometric parameters. Discordance between histology and one or more IHC parameters was seen in 5/25 (20% of patients with grade III astrocytoma and 9/25 (36% of patients with grade II disease. PCNA and p53 labeling indices were positively correlated with Pearson′s correlation, p less than 0.001 for both. Increased proliferative fraction, genetic alterations and neovascularization mark biological aggressiveness in astrocytoma. Immunohistochemical evaluation scores over meet the challenge of accurate prognostication of this potentially fatal malignancy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Shiu-Ru Lin; Yau-Jiunn Lee; Juei-Hsiung Tsai [Kaohsiung Medical College, Taiwan (China)

    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.

  9. Differential effects of garcinol and curcumin on histone and p53 modifications in tumour cells

    Directory of Open Access Journals (Sweden)

    Collins Hilary M

    2013-01-01

    , and was prevented by siRNA targeting of SUV420H2. Conclusion In summary, although garcinol and curcumin can both inhibit histone acetyltransferase activities, our results show that these compounds have differential effects on cancer cells in culture. Garcinol treatment alters expression of chromatin modifying enzymes in MCF7 cells, resulting in reprogramming of key histone and p53 PTMs and growth arrest, underscoring its potential as a cancer chemopreventive agent.

  10. Differential effects of garcinol and curcumin on histone and p53 modifications in tumour cells

    International Nuclear Information System (INIS)

    summary, although garcinol and curcumin can both inhibit histone acetyltransferase activities, our results show that these compounds have differential effects on cancer cells in culture. Garcinol treatment alters expression of chromatin modifying enzymes in MCF7 cells, resulting in reprogramming of key histone and p53 PTMs and growth arrest, underscoring its potential as a cancer chemopreventive agent

  11. p53 Family: Role of Protein Isoforms in Human Cancer

    Directory of Open Access Journals (Sweden)

    Jinxiong Wei

    2012-01-01

    Full Text Available TP53, TP63, and TP73 genes comprise the p53 family. Each gene produces protein isoforms through multiple mechanisms including extensive alternative mRNA splicing. Accumulating evidence shows that these isoforms play a critical role in the regulation of many biological processes in normal cells. Their abnormal expression contributes to tumorigenesis and has a profound effect on tumor response to curative therapy. This paper is an overview of isoform diversity in the p53 family and its role in cancer.

  12. Tumor hypoxia, p53, and prognosis in cervical cancers

    International Nuclear Information System (INIS)

    Background: The p53 protein is involved in the regulation of initiation of apoptosis. In vitro, p53-deficient cells do not respond to hypoxia with apoptosis as do p53-normal cells, and this may lead to a relative growth advantage of cells without a functioning p53 under hypoxia. On the basis of this hypothesis, a selection of cells with a functionally inactive p53 may occur in hypoxic tumors. The development of uterine cervical carcinomas is closely associated with infections of human papilloma viruses, which may cause a degradation of the tumor suppressor gene p53, resulting in a restriction of apoptosis. Thus, cervical cancers have often a functionally inactive p53. The purpose of our clinical study was therefore to investigate the association between p53, hypoxia, and prognosis in cervical cancers in which the oxygenation status can be determined by clinical methods. Material and Methods: Seventy patients with locally advanced squamous cell cervical cancer Stages IIB (n=14), IIIB (n=49), and IVA (n=7) were investigated in the period from 1996 through 1999. All were treated with definitive radiotherapy with curative intent by a combination of external radiotherapy plus high-dose-rate afterloading. Before therapy, tumor oxygenation was measured with a needle probe polarographically using the Eppendorf histograph. Hypoxic tumors were defined as those with pO2 measurements below 5 mm Hg (HF5). Pretreatment biopsies were taken and analyzed immunohistologically for p53 protein expression with the DO-7 antibody. The DNA index was measured by flow cytometry. The statistical data analysis was done with SPSS 9.0 for Windows. Results: The 3-year overall survival was 55% for the whole group of patients. Clinical prognostic factors in a multivariate analysis were pretreatment hemoglobin level (3-year survival 62% for patients with a pretreatment hemoglobin ≥11 g/dl vs. 27% for hemoglobin <11 g/dl, p=0.006) and FIGO stage (Stage IIB: 65%; Stage IIIB: 60%; Stage IVA: 29%, p

  13. Transcriptome profiling identifies genes and pathways deregulated upon floxuridine treatment in colorectal cancer cells harboring GOF mutant p53.

    Science.gov (United States)

    Datta, Arindam; Dey, Sanjib; Das, Pijush; Alam, Sk Kayum; Roychoudhury, Susanta

    2016-06-01

    Mutation in TP53 is a common genetic alteration in human cancers. Certain tumor associated p53 missense mutants acquire gain-of-function (GOF) properties and confer oncogenic phenotypes including enhanced chemoresistance. The colorectal cancers (CRC) harboring mutant p53 are generally aggressive in nature and difficult to treat. To identify a potential gene expression signature of GOF mutant p53-driven acquired chemoresistance in CRC, we performed transcriptome profiling of floxuridine (FUdR) treated SW480 cells expressing mutant p53(R273H) (GEO#: GSE77533). We obtained several genes differentially regulated between FUdR treated and untreated cells. Further, functional characterization and pathway analysis revealed significant enrichment of crucial biological processes and pathways upon FUdR treatment in SW480 cells. Our data suggest that in response to chemotherapeutics treatment, cancer cells with GOF mutant p53 can modulate key cellular pathways to withstand the cytotoxic effect of the drugs. The genes and pathways identified in the present study can be further validated and targeted for better chemotherapy response in colorectal cancer patients harboring mutant p53. PMID:27114909

  14. Activities of wildtype and mutant p53 in suppression of homologous recombination as measured by a retroviral vector system

    International Nuclear Information System (INIS)

    DNA repair of double strand breaks, interstrand DNA cross-links, and other types of DNA damage utilizes the processes of homologous recombination and non-homologous end joining to repair the damage. Aberrant homologous recombination is likely to be responsible for a significant fraction of chromosomal deletions, duplications, and translocations that are observed in cancer cells. To facilitate measurement of homologous recombination frequencies in normal cells, mutant cells, and cancer cells, we have developed a high titer retroviral vector containing tandem repeats of mutant versions of a GFP-Zeocin resistance fusion gene and an intact neomycin resistance marker. Recombination between the tandem repeats regenerates a functional GFP-ZeoR marker that can be easily scored. This retroviral vector was used to assess homologous recombination frequencies in human cancer cells and rodent fibroblasts with differing dosages of wild type or mutant p53. Absence of wild type p53 stimulated spontaneous and ionizing radiation-induced homologous recombination, confirming previous studies. Moreover, p53+/- mouse fibroblasts show elevated levels of homologous recombination compared to their p53+/+ counterparts following retroviral vector infection, indicating that p53 is haploinsufficient for suppression of homologous recombination. Transfection of vector-containing p53 null Saos-2 cells with various human cancer-associated p53 mutants revealed that these altered p53 proteins retain some recombination suppression function despite being totally inactive for transcriptional transactivation. The retroviral vector utilized in these studies may be useful in performing recombination assays on a wide array of cell types, including those not readily transfected by normal vectors

  15. Effects of serum starvation on radiosensitivity, proliferation and apoptosis in four human tumor cell lines with different p53 status

    International Nuclear Information System (INIS)

    Purpose: The effects of serum starvation on radiation sensitivity, cell proliferation and apoptosis were investigated with particular consideration of the p53 status. Material and Methods: Four human tumor cell lines, Be11 (melanoma, p53 wild-type), MeWo (melanoma, p53 mutant), 4197 (squamous cell carcinoma, p53 wild-type) and 4451 (squamous cell carcinoma, p53 mutant), were used. After the cells had been incubated in starvation medium (0.5% FCS) for 1-6 days, changes in cell cycle distribution, induction of apoptosis and necrosis, and changes in radiation sensitivity were assessed by two-parameter flow cytometric measurements of DNA content/BrdU labeling, two-parameter flow cytometric measurements of DNA-dye-exclusion/Annexin V binding, and a conventional colony assay, respectively. Results: p53 wild-type cell lines showed a decrease in the BrdU labeling index and an increase in the apoptotic cell frequency in starvation medium. p53 mutant cell lines showed a decrease in the BrdU labeling index but no evidence of apoptosis. These cells went into necrosis instead. The radiation sensitivity was increased in 4451 and slightly decreased in Be11 and 4197 in starvation medium. Conclusion: These data suggest a functional involvement of p53 in starvation-induced G1-block and apoptosis in tumor cells. Altered radiosensitivity after culture in starvation medium seemed to be explained at least in part by the starvation-induced G1-block. The frequency of starvation-induced apoptosis or necrosis was not correlated with radiation sensitivity. (orig.)

  16. Clinicopathologic significance of HIF-1α, p53, and VEGF expression and preoperative serum VEGF level in gastric cancer

    International Nuclear Information System (INIS)

    Hypoxia influences tumor growth by inducing angiogenesis and genetic alterations. Hypoxia-inducible factor 1α (HIF-1α), p53, and vascular endothelial growth factor (VEGF) are all important factors in the mechanisms inherent to tumor progression. In this work, we have investigated the clinicopathologic significance of HIF-1α, p53, and VEGF expression and preoperative serum VEGF (sVEGF) level in gastric cancer. We immunohistochemically assessed the HIF-1α, p53, and VEGF expression patterns in 114 specimens of gastric cancer. Additionally, we determined the levels of preoperative serum VEGF (sVEGF). The positive rates of p53 and HIF-1α (diffuse, deep, intravascular pattern) were 38.6% and 15.8%, respectively. The VEGF overexpression rate was 57.9%. p53 and HIF-1α were correlated positively with the depth of invasion (P = 0.015, P = 0.001, respectively). Preoperative sVEGF and p53 levels were correlated significantly with lymph node involvement (P = 0.010, P = 0.040, respectively). VEGF overexpression was more frequently observed in the old age group (≥ 60 years old) and the intestinal type (P = 0.013, P = 0.014, respectively). However, correlations between preoperative sVEGF level and tissue HIF-1α, VEGF, and p53 were not observed. The median follow-up duration after operation was 24.5 months. HIF-1α was observed to be a poor prognostic factor of disease recurrence or progression (P = 0.002). p53, HIF-1α and preoperative sVEGF might be markers of depth of invasion or lymph node involvement. HIF-1α expression was a poor prognostic factor of disease recurrence or progression in patients with gastric cancers

  17. Gene expression profiles after ionizing radiation in three closely related human lymphoblastoid cell lines with different p53 status

    International Nuclear Information System (INIS)

    Full text: The p53 protein has been implicated in multiple cellular responses related to DNA damage, including apoptosis, cell cycle control, as well as DNA replication, transcription, and repair. Alterations in any of these processes could be related to increased genomic instability. Our previous study indicated that the lack of wild-type p53 does not lead to increased mutability. To investigate further how p53 is involved in regulating mutational processes, we used 8K cDNA microarrays to compare the patterns of gene expression among three closely related human cell lines with different p53 status including TK6 (wild-type p53), NH32 (p53-null), and WTK1 (mutant p53). Total RNA samples were collected at different time points (1, 3, 6, 9, and 24h) after 10Gy gamma-radiation. After template-based clustering analysis of the gene expression over the time course, our preliminary results showed that 464 genes are either up- or down-regulated by 2 fold following 10Gy radiation treatment. In addition, cluster analyses of gene expression profiles among these three cell lines revealed distinct patterns. In TK6, 175 genes were being up-regulated, while 36 genes showed down-regulation. In contrast, WTK1 showed 75 genes being up-regulated and 12 genes being down-regulated. In NH32, only 54 genes showed up-regulation. Furthermore, we found several genes associated with DNA repair such as DDB2, p53R2, XPC, PCNA, BTG2 and MSH2 were highly induced in TK6 compared to WTK1 and NH32. These TK6 up-regulated genes were confirmed by using real-time RT-PCR and are being further investigated at the protein level by Western blots

  18. P53 GENE MUTATIONS IN NON-SMALL CELL LUNG CANCER DETECTED BY POLYMERASE CHAIN REACTION SINGLE-STRAND CONFORMATION POLYMORPHISM ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    赵永良; 吴德昌; 项晓琼; 张宝仁; 周乃康; 胡迎春

    1999-01-01

    Mutations of the p53 tumor suppressor gone are the most frequent genetic akerations detected in human lung cancer. To assess the pathogenic significance of p53 gone alterations in Chlnege non-small cell lung cancer (NSCLC), 74 paired samples of primary lung cancer and normal lung tissue far away from the cancer were analyzed for mutations of the p53 gene(exons 5-8) using exon-specific PCR, single-gtrand conformation polymorphimax (PCR-SSCP). p53 mutations were observed in 55.4% (41/74) of the samples.No linkaiges were detected between the incidence of p53 mutations and histological type, lymph node metastasis, age or sex. Significant association between p53 mutations and degree of differentiation in edenotmremmnas, not in squamous cell carcinomas, was observed, The frequency of p53 mutations in(65. 3%) was higher than in nonsmokers (33. 3%) and reached stafisrical significance. We also found p53 mutations in 6/7 samples which had tissue invasion and distant metastasis. These results suggest that smcking could be an important factor in lung carcinogenesis, p53 mutation is a worse prognosis indicator in ade and nocarcinomas and related to high aggressive behavior of human lung cancer.

  19. Activation of p53 in Down Syndrome and in the Ts65Dn Mouse Brain is Associated with a Pro-Apoptotic Phenotype.

    Science.gov (United States)

    Tramutola, Antonella; Pupo, Gilda; Di Domenico, Fabio; Barone, Eugenio; Arena, Andrea; Lanzillotta, Chiara; Broekaart, Diede; Blarzino, Carla; Head, Elizabeth; Butterfield, D Allan; Perluigi, Marzia

    2016-03-01

    Down syndrome (DS) is the most common genetic cause of intellectual disability, resulting from trisomy of chromosome 21. The main feature of DS neuropathology includes early onset of Alzheimer's disease (AD), with deposition of senile plaques and tangles. We hypothesized that apoptosis may be activated in the presence of AD neuropathology in DS, thus we measured proteins associated with upstream and downstream pathways of p53 in the frontal cortex from DS cases with and without AD pathology and from Ts65Dn mice, at different ages. We observed increased acetylation and phosphorylation of p53, coupled to reduced MDM2/p53 complex level and lower levels of SIRT1. Activation of p53 was associated with a number of targets (BAX, PARP1, caspase-3, p21, heat shock proteins, and PGC1α) that were modulated in both DS and DS/AD compared with age-matched controls. In particular, the most relevant changes (increased p-p53 and acetyl-p53 and reduced formation of MDM2/p53 complex) were found to be modified only in the presence of AD pathology in DS. In addition, a similar pattern of alterations in the p53 pathway was found in Ts65Dn mice. These results suggest that p53 may integrate different signals, which can result in a pro-apoptotic-phenotype contributing to AD neuropathology in people with DS. PMID:26967221

  20. Transfection of p53-knockout mouse fibroblasts with wild-type p53 increases the thermo sensitivity and stimulates apoptosis induced by heat stress

    International Nuclear Information System (INIS)

    Purpose: The relationship between p53 functions and cellular thermo sensitivity was evaluated using murine fibroblasts transfected with either wild-type p53 or mutated p53, or those with a null p53 genotype. Methods and Materials: Cellular thermo sensitivity was determined using the clonogenic assay. Cell cycle distribution was assayed by determining DNA content using flow cytometry. Apoptosis was analyzed by detection of both apoptotic bodies and DNA fragmentation. Results: Stable transfectant with either wild-type p53 or mutated p53 was established. The transfectants with wild-type p53 were more thermo sensitive than either those with a null p53 or with mutated p53. Although heat-induced G1 cell cycle arrest was substantially observed in all transfectants, wild-type p53 enhanced and prolonged the G1 arrest; furthermore, wild-type p53 stimulated the induction of apoptosis by heat stress, whereas mutated p53 delayed it extremely. Conclusion: The p53 gene is a factor for determining cellular thermo sensitivity and wild-type p53 contributes to thermo sensitization resulting in enhancement of heat-induced apoptosis

  1. Transfection of p53-knockout mouse fibroblasts with wild-type p53 increases the thermo sensitivity and stimulates apoptosis induced by heat stress

    International Nuclear Information System (INIS)

    Purpose: The relationship between the p53 functions and cellular thermo sensitivity was evaluated using murine fibroblasts transfected with either wild-type p53 or mutated p53, or those with a null p53 genotype. Methods and Materials: Cellular thermo sensitivity was determined using the clonogenic assay. Cell cycle distribution was assayed by determining DNA content using flow cytometer. Apoptosis was analyzed by detection of both apoptotic bodies and DNA fragmentation. Results: Stable transfectant with either wild-type p53 or mutated p53 was established. The transfectants with wild-type p53 were more thermo sensitive than either those with a null p53 or with mutated p53. Although heat-induced G1 cell cycle arrest was substantially observed in all transfectants, wild-type p53 enhanced and prolonged the G1 arrest. Furthermore, wild-type p53 stimulated the induction of apoptosis by heat stress, whereas mutated p53 delayed it extremely. Conclusion: The p53 gene is at least a factor for determining cellular thermo sensitivity and wild-type p53 contributes to thermo sensitization resulting in enhancement of heat-induced apoptosis

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

    Energy Technology Data Exchange (ETDEWEB)

    Wallentine, Brad D.; Wang, Ying; Tretyachenko-Ladokhina, Vira; Tan, Martha; Senear, Donald F. [University of California, Irvine, Irvine, CA 92697 (United States); Luecke, Hartmut, E-mail: hudel@uci.edu [University of California, Irvine, Irvine, CA 92697 (United States); University of California, Irvine, Irvine, CA 92697 (United States); University of California, Irvine, Irvine, CA 92697 (United States); University of California, Irvine, Irvine, CA 92697 (United States); Universidad del Pais Vasco, 48940 Leioa (Spain)

    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

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

    International Nuclear Information System (INIS)

    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−1 (15.1 kJ mol−1). Further biochemical evidence shows that each suppressor mutation, N235K or N239Y, acts individually to restore thermodynamic stability to V157F and that both together are more effective than either alone. All rescued mutants were found to have wild-type DNA-binding activity when assessed at a permissive temperature, thus pointing to thermodynamic stability as the critical underlying variable. Interestingly, thermodynamic analysis shows that while N239Y demonstrates stabilization of the wild-type p53 core domain, N235K does not. These observations suggest distinct structural mechanisms of rescue. A new salt bridge between Lys235 and Glu198, found in both the N235K and rescued cancer mutant structures, suggests a rescue mechanism that relies on stabilizing the β-sandwich scaffold. On the

  4. Translational approaches targeting the p53 pathway for anti-cancer therapy

    OpenAIRE

    Essmann, Frank; Schulze-Osthoff, Klaus

    2012-01-01

    The p53 tumour suppressor blocks cancer development by triggering apoptosis or cellular senescence in response to oncogenic stress or DNA damage. Consequently, the p53 signalling pathway is virtually always inactivated in human cancer cells. This unifying feature has commenced tremendous efforts to develop p53-based anti-cancer therapies. Different strategies exist that are adapted to the mechanisms of p53 inactivation. In p53-mutated tumours, delivery of wild-type p53 by adenovirus-based gen...

  5. The P53 Codon 72 SNP and Lung Cancer

    Czech Academy of Sciences Publication Activity Database

    Biroš, Erik; Biroš, I.; Kohout, A.; Kalina, I.; Bogyiova, E.; Stubna, J.

    Ghent: organising comittee, 2001. s. -. [Annual Meeting of the European Environmental Mutagen Society /31./. 01.09.2001-05.09.2001, Ghent] Institutional research plan: CEZ:AV0Z5039906 Keywords : p53 gene expression * lung cancer Subject RIV: DN - Health Impact of the Environment Quality

  6. NRF2 and p53: Januses in cancer?

    Science.gov (United States)

    Rotblat, Barak; Melino, Gerry; Knight, Richard A.

    2012-01-01

    The transcription factor nuclear factor (erythroid-derived 2)-like 2, also known as NFE2L2 or NRF2, is a master regulator of the anti-oxidative stress response and positively controls the expression of a battery of anti-oxidative stress response proteins and enzymes implicated in detoxification and glutathione generation. Although its detoxifying activity is important in cancer prevention, it has recently been shown that cancer cells also exploit its protective functions to thrive and resist chemotherapy. NRF2 was also shown to the pentose phosphate pathway and glutaminolysis, which promotes purine synthesis for supporting rapid proliferation and glutathione for providing anti-oxidative stress protection. Evidence obtained from cancer patients and cell lines suggest that NRF2 is highly active in a variety of human cancers and is associated with aggressiveness. p53 is a tumor suppressor that also promotes an anti-oxidative stress metabolic program and glutaminolysis. Here we will discuss the similarities between NRF2 and p53 and review evidence that p53 might be exploited by cancer cells to gain protection against oxidative stress, as is the case for NRF2. We discuss findings of co-regulation between these transcription factors and propose possible therapeutic strategies that can be used for treatment of cancers that harbor WT p53 and express high levels of NRF2. PMID:23174755

  7. Immunohistochemical detection of P53 and Mdm2 in vitiligo

    Directory of Open Access Journals (Sweden)

    Ola A Bakry

    2012-01-01

    Full Text Available Background: Vitiligo is a common depigmented skin disorder that is caused by selective destruction of melanocytes. It is generally accepted that the main function of melanin resides in the protection of skin cells against the deleterious effect of ultraviolet rays (UVRs. Association of vitiligo and skin cancer has been a subject of controversy. Occurrence of skin cancer in long-lasting vitiligo is rare despite multiple evidences of DNA damage in vitiliginous skin. Aim: To detect the expression of P53 and Mdm2 proteins in both depigmented and normally pigmented skin of vitiligo patients and to compare it to control subjects suffering from nonmelanoma skin cancer (NMSC. Materials and Methods: Thirty-four patients with vitiligo and 30 age and sex-matched patients with nodulo-ulcerative basal cell carcinoma (BCC as a control group were selected. Both patients and control subjects had outdoor occupations. Skin biopsies were taken from each case and control subjects. Histopathological examination of Hematoxylin and eosin-stained sections was done. Expression of P53 and Mdm2 proteins were examined immunohistochemically. Results: Both P53 and Mdm2 were strongly expressed in depigmented as well as normally pigmented skin of vitiligo patients. This expression involved the epidermis, skin adnexa and blood vessels with significant differences between cases and controls. Conclusions: The overexpression of P53 and Mdm2 proteins in both normally pigmented and depigmented skin of patients with vitiligo could contribute to the decreased occurrence of actinic damage and NMSC in these patients.

  8. A role for p53 in selenium-induced senescence

    Science.gov (United States)

    The tumor suppressor p53 and the ataxia-telangiectasia mutated (ATM) kinase play important roles in the senescence response to oncogene activation and DNA damage. We have previously shown that selenium-containing compounds can activate an ATM-dependent senescence response in MRC-5 normal fibroblasts...

  9. Tumour suppression in skin and other tissues via cross-talk between vitamin D- and p53-signalling

    Directory of Open Access Journals (Sweden)

    Joerg eReichrath

    2014-06-01

    Full Text Available P53 and its family members have been implicated in the direct regulation of the vitamin D receptor (VDR. Vitamin D- and p53-signaling pathways have a significant impact on spontaneous or carcinogen-induced malignant transformation of cells, with VDR and p53 representing important tumour suppressors. VDR and the p53/p63/p73 proteins all function typically as receptors or sensors that turn into transcriptional regulators upon stimulus, with the main difference being that the nuclear VDR is activated as a transcription factor after binding its naturally occurring ligand 1,25-dihydroxyvitamin D with high affinity while the p53 family of transcription factors, mostly in the nucleoplasm, responds to a large number of alterations in cell homeostasis commonly referred to as stress. An increasing body of evidence now convincingly demonstrates a cross-talk between vitamin D- and p53-signaling that occurs at different levels, has genome-wide implications and that should be of high importance for many malignancies, including non-melanoma skin cancer. One interaction involves the ability of p53 to increase skin pigmentation via POMC derivatives including alpha-MSH and ACTH. Pigmentation protects the skin against UV-induced DNA damage and skin carcinogenesis, yet on the other hand reduces cutaneous synthesis of vitamin D. A second level of interaction may be through the ability of 1,25-dihydroxyvitamin D to increase the survival of skin cells after UV irradiation. UV irradiation-surviving cells show significant reductions in thymine dimers in the presence of 1,25-dihydroxyvitamin D that are associated with increased nuclear p53 protein expression, and significantly reduced NO products. A third level of interaction is documented by the ability of vitamin D compounds to regulate the expression of the murine double minute 2 (MDM2 gene in dependence of the presence of wild-type p53. MDM2 has a well established role as a key negative regulator of p53 activity

  10. Maintaining appearances-The role of p53 in adult neurogenesis

    International Nuclear Information System (INIS)

    In the adult mammalian brain, neuronal turnover continues to replenish cells in existing neuronal circuits, such as those involved either in odor discrimination or in learning and memory, throughout life. With age, however, the capacity for neurogenesis diminishes and these functions become impaired. Neuronal turnover is a two-step process, which first generates excess neuronal progenitors and then eliminates all but the few that differentiate into fully functional neurons. This process requires a fine balance between cell proliferation and cell death. Altered activity of the tumor suppressor p53 can upset this balance by affecting the rate of cell proliferation, but not the rate of cell death, in neurogenic regions of the adult brain. Genetically engineered mice in which p53 activity is increased demonstrate that premature loss of neurogenic capacity is linked to accelerated organismal aging

  11. The epidemiology of Her-2/ neu and P53 in breast cancer

    Directory of Open Access Journals (Sweden)

    Bernstein Jonine L.

    1999-01-01

    Full Text Available Breast cancer is an etiologically heterogeneous disease with marked geographical variations. Joint consideration of the relationship between specific molecular alterations and known or suspected epidemiologic risk factors for this disease should help distinguish subgroups of women that are at elevated risk of developing breast cancer. In this article, we present a comprehensive literature review of the etiologic and prognostic roles of Her-2/neu and P53 among women. In addition, we discuss the advantages and limitations of using biomarkers in epidemiological studies. We conclude that more research is needed to understand the complex relationships between genetic alterations and etiologic risk factors for breast cancer.

  12. Re-Engineered p53 Chimera with Enhanced Homo-Oligomerization That Maintains Tumor Suppressor Activity

    OpenAIRE

    Okal, Abood; Cornillie, Sean; Matissek, Stephan J.; Matissek, Karina J.; Cheatham, Thomas E.; Lim, Carol S

    2014-01-01

    The use of the tumor suppressor p53 for gene therapy of cancer is limited by the dominant negative inactivating effect of mutant endogenous p53 in cancer cells. We have shown previously that swapping the tetramerization domain (TD) of p53 with the coiled-coil (CC) from Bcr allows for our chimeric p53 (p53-CC) to evade hetero-oligomerization with endogenous mutant p53. This enhances the utility of this construct, p53-CC, for cancer gene therapy. Because domain swapping to create p53-CC could r...

  13. Pla2g16 phospholipase mediates gain-of-function activities of mutant p53.

    Science.gov (United States)

    Xiong, Shunbin; Tu, Huolin; Kollareddy, Madhusudhan; Pant, Vinod; Li, Qin; Zhang, Yun; Jackson, James G; Suh, Young-Ah; Elizondo-Fraire, Ana C; Yang, Peirong; Chau, Gilda; Tashakori, Mehrnoosh; Wasylishen, Amanda R; Ju, Zhenlin; Solomon, Hilla; Rotter, Varda; Liu, Bin; El-Naggar, Adel K; Donehower, Lawrence A; Martinez, Luis Alfonso; Lozano, Guillermina

    2014-07-29

    p53(R172H/+) mice inherit a p53 mutation found in Li-Fraumeni syndrome and develop metastatic tumors at much higher frequency than p53(+/-) mice. To explore the mutant p53 metastatic phenotype, we used expression arrays to compare primary osteosarcomas from p53(R172H/+) mice with metastasis to osteosarcomas from p53(+/-) mice lacking metastasis. For this study, 213 genes were differentially expressed with a P value ETS2 suppressed mutant p53 induction of Pla2g16. Thus, our study identifies a phospholipase as a transcriptional target of mutant p53 that is required for metastasis. PMID:25024203

  14. Modulation of p53β and p53γ expression by regulating the alternative splicing of TP53 gene modifies cellular response

    OpenAIRE

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

    2014-01-01

    In addition to the tumor suppressor p53 protein, also termed p53α, the TP53 gene produces p53β and p53γ through alternative splicing of exons 9β and 9γ located within TP53 intron 9. Here we report that both TG003, a specific inhibitor of Cdc2-like kinases (Clk) that regulates the alternative splicing pre-mRNA pathway, and knockdown of SFRS1 increase expression of endogenous p53β and p53γ at mRNA and protein levels. Development of a TP53 intron 9 minigene shows that TG003 treatment and knockdo...

  15. Differential regulation of the REGγ–proteasome pathway by p53/TGF-β signalling and mutant p53 in cancer cells

    OpenAIRE

    Ali, Amjad; Wang, Zhuo; Fu, Junjiang; Lei, Ji; Liu, Jiang; Lei, Li; Wang,; Chen, Jiwu; Caulin, Carlos; Jeffrey, N. Myers; Zhang, Pei; Xiao, Jianru; Zhang, Bianhong; Li, Xiaotao

    2013-01-01

    Proteasome activity is frequently enhanced in cancer to accelerate metastasis and tumorigenesis. REGγ, a proteasome activator known to promote p53/p21/p16 degradation, is often overexpressed in cancer cells. Here we show that p53/TGF-β signalling inhibits the REGγ–20S proteasome pathway by repressing REGγ expression. Smad3 and p53 interact on the REGγ promoter via the p53RE/SBE region. Conversely, mutant p53 binds to the REGγ promoter and recruits p300. Importantly, mutant p53 prevents Smad3/...

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

    Science.gov (United States)

    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.

  17. Construction of a triple modified p53 containing DNA vaccine to enhance processing and presentation of the p53 antigen

    NARCIS (Netherlands)

    Hospers, Geke A. P.; Meijer, Coby; Dam, Wendy A.; Roossink, Frank; Mulder, Nanno H.

    2009-01-01

    More effective and less toxic treatments are urgently needed in the treatment of patients with cancer. The turnout suppressor protein p53 is a tumour-associated antigen that could serve that purpose when applied in an immunologic approval to cancer. It is mutated in similar to 50% of the tumours res

  18. P53-specific T cell responses in patients with malignant and benign ovarian tumors : Implications for p53 based immunotherapy

    NARCIS (Netherlands)

    Lambeck, Annechien; Leffers, Ninke; Hoogeboom, Baukje-Nynke; Sluiter, Wim; Hamming, Ineke; Klip, Harry; ten Hoor, Klaske; Esajas, Martha; van Oven, Magda; Drijfhout, Jan-Wouter; Platteel, Inge; Offringa, Rienk; Hollema, Harry; Melief, Kees; van der Burg, Sjoerd; van der Zee, Ate; Daemen, Toos; Nijman, Hans

    2007-01-01

    Despite intensive treatment, 70% of the ovarian cancer patients will develop recurrent disease, emphasizing the need for new approaches such as immunotherapy. A promising antigenic target for immunotherapy in ovarian cancer is the frequently overexpressed p53 protein. The aim of the study was to eva

  19. ETS2 overexpression in transgenic models and in Down syndrome predisposes to apoptosis via the p53 pathway.

    Science.gov (United States)

    Wolvetang, E J; Wilson, T J; Sanij, E; Busciglio, J; Hatzistavrou, T; Seth, A; Hertzog, P J; Kola, I

    2003-02-01

    ETS2 is a transcription factor encoded by a gene on human chromosome 21 and alterations in its expression have been implicated in the pathophysiological features of Down syndrome (DS). This study demonstrates that overexpression of ETS2 results in apoptosis. This is shown in a number of circumstances, including ETS2-overexpressing transgenic mice and cell lines and in cells from subjects with DS. Indeed we report for the first time that the ETS2 overexpression transgenic mouse develops a smaller thymus and lymphocyte abnormalities similar to that observed in DS. In all circumstances of ETS2 overexpression, the increased apoptosis correlated with increased p53 and alterations in downstream factors in the p53 pathway. In the human HeLa cancer cell line, transfection with functional p53 enables ETS2 overexpression to induce apoptosis. Furthermore, crossing the ETS2 transgenic mice with p53(-/-) mice genetically rescued the thymic apoptosis phenotype. Therefore, we conclude that overexpression of human chromosome 21-encoded ETS2 induces apoptosis that is dependent on p53. These results have important consequences for understanding DS and oncogenesis and may provide new insights into therapeutic interventions. PMID:12554679

  20. Paracrine Apoptotic Effect of p53 Mediated by Tumor Suppressor Par-4

    Directory of Open Access Journals (Sweden)

    Ravshan Burikhanov

    2014-01-01

    Full Text Available The guardian of the genome, p53, is often mutated in cancer and may contribute to therapeutic resistance. Given that p53 is intact and functional in normal tissues, we harnessed its potential to inhibit the growth of p53-deficient cancer cells. Specific activation of p53 in normal fibroblasts selectively induced apoptosis in p53-deficient cancer cells. This paracrine effect was mediated by p53-dependent secretion of the tumor suppressor Par-4. Accordingly, the activation of p53 in normal mice, but not p53−/− or Par-4−/− mice, caused systemic elevation of Par-4, which induced apoptosis of p53-deficient tumor cells. Mechanistically, p53 induced Par-4 secretion by suppressing the expression of its binding partner, UACA, which sequesters Par-4. Thus, normal cells can be empowered by p53 activation to induce Par-4 secretion for the inhibition of therapy-resistant tumors.

  1. Identification of two novel functional p53 responsive elements in the Herpes Simplex Virus-1 genome

    OpenAIRE

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

    2014-01-01

    Analysis of the herpes simplex virus-1 (HSV-1) genome reveals two candidate p53 responsive elements (p53RE), located in proximity to the replication origins oriL and oriS, referred to as p53RE-L and p53RE-S, respectively. The sequences of p53RE-L and p53RE-S conform to the p53 consensus site and are present in HSV-1 strains KOS, 17, and F. p53 binds to both elements in vitro and in virus-infected cells. Both p53RE-L and p53RE-S are capable of conferring p53-dependent transcriptional activatio...

  2. Disruption of focal adhesion kinase and p53 interaction with small molecule compound R2 reactivated p53 and blocked tumor growth

    International Nuclear Information System (INIS)

    Focal Adhesion Kinase (FAK) is a 125 kDa non-receptor kinase that plays a major role in cancer cell survival and metastasis. We performed computer modeling of the p53 peptide containing the site of interaction with FAK, predicted the peptide structure and docked it into the three-dimensional structure of the N-terminal domain of FAK involved in the complex with p53. We screened small molecule compounds that targeted the site of the FAK-p53 interaction and identified compounds (called Roslins, or R compounds) docked in silico to this site. By different assays in isogenic HCT116p53+/+ and HCT116 p53-/- cells we identified a small molecule compound called Roslin 2 (R2) that bound FAK, disrupted the binding of FAK and p53 and decreased cancer cell viability and clonogenicity in a p53-dependent manner. In addition, dual-luciferase assays demonstrated that the R2 compound increased p53 transcriptional activity that was inhibited by FAK using p21, Mdm-2, and Bax-promoter targets. R2 also caused increased expression of p53 targets: p21, Mdm-2 and Bax proteins. Furthermore, R2 significantly decreased tumor growth, disrupted the complex of FAK and p53, and up-regulated p21 in HCT116 p53+/+ but not in HCT116 p53-/- xenografts in vivo. In addition, R2 sensitized HCT116p53+/+ cells to doxorubicin and 5-fluorouracil. Thus, disruption of the FAK and p53 interaction with a novel small molecule reactivated p53 in cancer cells in vitro and in vivo and can be effectively used for development of FAK-p53 targeted cancer therapy approaches

  3. Low doses of arsenic, via perturbing p53, promotes tumorigenesis.

    Science.gov (United States)

    Ganapathy, Suthakar; Li, Ping; Fagman, Johan; Yu, Tianqi; Lafontant, Jean; Zhang, Guojun; Chen, Changyan

    2016-09-01

    In drinking water and in workplace or living environments, low doses of arsenic can exist and operate as a potent carcinogen. Due to insufficient understanding and information on the pervasiveness of environmental exposures to arsenic, there is an urgent need to elucidate the underlying molecular mechanisms of arsenic regarding its carcinogenic effect on human health. In this study, we demonstrate that low doses of arsenic exposure mitigate or mask p53 function and further perturb intracellular redox state, which triggers persistent endoplasmic reticulum (ER) stress and activates UPR (unfolded protein response), leading to transformation or tumorigenesis. Thus, the results suggest that low doses of arsenic exposure, through attenuating p53-regulated tumor suppressive function, change the state of intracellular redox and create a microenvironment for tumorigenesis. Our study also provides the information for designing more effective strategies to prevent or treat human cancers initiated by arsenic exposure. PMID:27425828

  4. P53 gene mutations and risk factors in Egyptian laryngeal cancer patients

    International Nuclear Information System (INIS)

    Laryngeal cancer (LC) is one of the most fatal cancers in the world; it represents the sixth most common cancer in the world and the second most common respiratory cancer, with approximately 500,000 new cases worldwide, annually. The mechanisms of tumorigenesis in LC remain unknown, although smoking and alcohol consumption are considered to be major risk factors. Numerous genetic alterations have been described in laryngeal squamous cell carcinoma, but the molecular mechanisms contributing to initiation and progression of laryngeal are still poorly understood. Mutations within P53 have been strongly implicated as frequent events in several cancers. In the present study, exons 5-8 of P53 for mutations in DNA from tumor biopsies (n 50), beside 20 samples of normal tissues adjacent to the malignant area, blood samples (n = 25) from the LC patients, and blood samples from a healthy, matched control group (n = 20), were screened using polymerase chain reaction, single-strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing was done . Significant positive correlations were found between the occurrence of LC and age and smoking. In tumor-derived samples, mutations were found in three of the exons under investigation, representing 18 % of the samples. The mutations were unique to the tumor biopsies, indicating a somatic origin for mutations. The data confirm that the exons 6-8 of P53 is a mutational hotspot for laryngeal cancers in Egypt; ten mutations were found within this region.

  5. p53 spreads out further:suppression of EMT and stemness by activating miR-200c expression

    Institute of Scientific and Technical Information of China (English)

    J(o)rg Schubert; Thomas Brabletz

    2011-01-01

    @@ There is no need to emphasize the overwhelming importance of p53 for crucial cellular processes and of genetic alterations resulting from its loss of function or a dominant oncogenic mutant in many human cancer types.These functions are well described and include control of cell cycle progression, apoptosis, senescence, DNA-repair mechanisms and autophagy[1].

  6. Electrophoretic detection of protein p53 in human leukocytes

    International Nuclear Information System (INIS)

    The authors have found an acid-soluble protein with mol. wt. of about 53 kD in peripheral blood leukocytes of persons with Down's syndrome. It was present in different quantities in all 20 patients tested, but was virtually not discovered in 12 healthy blood donors. This paper determines the possible identity of this protein with protein p53 from mouse ascites carcinoma by comparing their electrophoretic mobilities, because the accuracy of electrophoretic determination of the molecular weight of proteins is not sufficient to identify them. The paper also describes experiments to detect a protein with electrophoretic mobility identical with that of a protein in the leukocytes of patients with Down's syndrome in leukocytes of patients with leukemia. To discover if protein p53 is involved in cell proliferation, the protein composition of leukocytes from healthy blood donors, cultured in the presence and absence of phytohemagglutinin (PHA), was compared. Increased incorporation of H 3-thymidine by leukocytes of patients with Down's syndrome is explained by the presence of a population of immature leukocytes actively synthesizing DNA in the peripheral blood of these patients, and this can also explain the presence of protein p53 in the leukocytes of these patients

  7. p53 gene targeting by homologous recombination in fish ES cells.

    Directory of Open Access Journals (Sweden)

    Yan Yan

    Full Text Available BACKGROUND: Gene targeting (GT provides a powerful tool for the generation of precise genetic alterations in embryonic stem (ES cells to elucidate gene function and create animal models for human diseases. This technology has, however, been limited to mouse and rat. We have previously established ES cell lines and procedures for gene transfer and selection for homologous recombination (HR events in the fish medaka (Oryzias latipes. METHODOLOGY AND PRINCIPAL FINDINGS: Here we report HR-mediated GT in this organism. We designed a GT vector to disrupt the tumor suppressor gene p53 (also known as tp53. We show that all the three medaka ES cell lines, MES1∼MES3, are highly proficient for HR, as they produced detectable HR without drug selection. Furthermore, the positive-negative selection (PNS procedure enhanced HR by ∼12 folds. Out of 39 PNS-resistant colonies analyzed, 19 (48.7% were positive for GT by PCR genotyping. When 11 of the PCR-positive colonies were further analyzed, 6 (54.5% were found to be bona fide homologous recombinants by Southern blot analysis, sequencing and fluorescent in situ hybridization. This produces a high efficiency of up to 26.6% for p53 GT under PNS conditions. We show that p53 disruption and long-term propagation under drug selection conditions do not compromise the pluripotency, as p53-targeted ES cells retained stable growth, undifferentiated phenotype, pluripotency gene expression profile and differentiation potential in vitro and in vivo. CONCLUSIONS: Our results demonstrate that medaka ES cells are proficient for HR-mediated GT, offering a first model organism of lower vertebrates towards the development of full ES cell-based GT technology.

  8. p53 gene in treatment of hepatic carcinoma:Status quo

    Institute of Scientific and Technical Information of China (English)

    Yong-Song Guan; Zi La; Lin Yang; Qing He; Ping Li

    2007-01-01

    Hepatocellular carcinoma(HCC)is one of the 10 most common cancers worldwide.There is no ideal treatment for HCC yet and many researchers are trying to improve the effects of treatment by changing therapeutic strategies.As the majority of human cancers seem to exhibit either abnormal p53 gene or disrupted p53 gene activation pathways,intervention to restore wild-type p53 (wt-p53)activities is an attractive anti-cancer therapy including HCC.Abnormalities of p53 are also considered a predisposition factor for hepatocarcinogenesis.p53 is frequently mutated in HCC.Most HCCs have defects in the p53-mediated apoptotic pathway although they carry wt-p53.High expression of p53 in vivo may exert therapeutic effects on HCC in two aspects:(1)High expression of exogenous p53 protein induces apoptosis of tumor cells by inhibiting proliferation of cells through several biologic pathways and(2)Exogenous p53 renders HCC more sensitive to some chemotherapeutic agents.Several approaches have been designed for the treatment of HCC via the p53 pathway by restoring the tumor suppression function from inactivation,rescuing the mutated p53 gene from instability,or delivering therapeutic exogenous p53.Products with p53 status as the target have been studied extensively in vitro and in vivo.This review elaborates some therapeutic mechanisms and advances in using recombinant human adenovirus p53 and oncolytic virus products for the treatment of HCC.

  9. Release of targeted p53 from the mitochondrion as an early signal during mitochondrial dysfunction

    Science.gov (United States)

    Increased accumulation of p53 tumor suppressor protein is an early response to low-level stressors. To investigate the fate of mitochondrial-sequestered p53, mouse embryonic fibroblast cells (MEFs) on a p53-deficient genetic background were transfected with p53-EGFP fusion protei...

  10. Mutant Mice Lacking the p53 C-Terminal Domain Model Telomere Syndromes

    NARCIS (Netherlands)

    Simeonova, I.; Jaber, S.; Draskovic, I.; Bardot, B.; Fang, M.; Bouarich-Bourimi, R.; Lejour, V.; Charbonnier, L.; Soudais, C.; Bourdon, J.C.; Huerre, M.; Londono-Vallejo, A.; Toledo, F.

    2013-01-01

    Mutations in p53, although frequent in human cancers, have not been implicated in telomere-related syndromes. Here, we show that homozygous mutant mice expressing p53(Delta31), a p53 lacking the C-terminal domain, exhibit increased p53 activity and suffer from aplastic anemia and pulmonary fibrosis,

  11. Regulation of transcription of the human presenilin-1 gene by ets transcription factors and the p53 protooncogene.

    Science.gov (United States)

    Pastorcic, M; Das, H K

    2000-11-10

    The expression of the human presenilin-1 cellular gene is suppressed by the p53 protooncogene. The rapid kinetic of the down-regulation has suggested that it may result from a primary mechanism. We show here that p53 also suppresses the transcription of a presenilin-1 promoter-chloramphenicol acetyltransferase reporter synthetic gene in transient infection assays in neuroblastoma (SK-N-SH) and hepatoma (HepG2) cell lines. Only a minimum promoter including sequences from -35 to + 6 from the transcription initiation is sufficient to confer down-regulation. We have previously defined a crucial DNA element controlling 90% of the expression of the gene within the same short area, and the identification of the transcription factors involved should also provide insights into the regulation of PS1 by p53. This region contains an Ets transcription factor binding motif, and a 2-base pair alteration within the core sequence (GGAA to TTAA) of the Ets consensus also reduced transcription by more than 90%. We now show that Ets1 and Ets2 indeed transactivate a PS1 promoter-chloramphenicol acetyltransferase reporter including the (-35 to +6) fragment. Furthermore, in vitro translated Ets2 binds specifically to the -10 Ets motif in electrophoretic mobility shift assays. Therefore, Ets1/2 factors bind specifically to the -10 Ets element and activate PS1 transcription. We also show that the coactivator p300 enhances the activation by Ets1 and Ets2 as well as the repression by p53. p300 is known to interact with p53 as well as with Ets1 and Ets2. We show that p53 does not bind directly to the PS1 promoter. Hence the repression of PS1 transcription by p53 is likely to be mediated through protein-protein interactions. PMID:10942770

  12. Ser18 and 23 phosphorylation is required for p53-dependent apoptosis and tumor suppression

    OpenAIRE

    Chao, Connie; Herr, Deron; Chun, Jerold; Xu, Yang

    2006-01-01

    Mouse p53 is phosphorylated at Ser18 and Ser23 after DNA damage. To determine whether these two phosphorylation events have synergistic functions in activating p53 responses, we simultaneously introduced Ser18/23 to Ala mutations into the endogenous p53 locus in mice. While partial defects in apoptosis are observed in p53S18A and p53S23A thymocytes exposed to IR, p53-dependent apoptosis is essentially abolished in p53S18/23A thymocytes, indicating that these two events have critical and syner...

  13. Evidence for allosteric variants of wild-type p53, a tumour suppressor protein.

    OpenAIRE

    Cook, A; Milner, J

    1990-01-01

    A tumour suppressor function for p53 is indicated in human lung cancer and in carcinoma of the colorectum. Loss of suppressor function, by mutation of the p53 gene, is associated with activation of p53 as an oncogene. The suppressor (wild type) and oncogenic (mutant) forms of the murine p53 protein are distinguishable at the molecular level by reactivity with anti-p53 monoclonal antibodies. For example, activated mutant p53 fails to react with PAb246 (p53-246 degrees). We now demonstrate that...

  14. p53-Induced Growth Arrest Is Regulated by the Mitochondrial SirT3 Deacetylase

    OpenAIRE

    SiDe Li; Michaela Banck; Shiraz Mujtaba; Ming-Ming Zhou; Mary M Sugrue; Walsh, Martin J

    2010-01-01

    A hallmark of p53 function is to regulate a transcriptional program in response to extracellular and intracellular stress that directs cell cycle arrest, apoptosis, and cellular senescence. Independent of the role of p53 in the nucleus, some of the anti-proliferative functions of p53 reside within the mitochondria [1]. p53 can arrest cell growth in response to mitochondrial p53 in an EJ bladder carcinoma cell environment that is naïve of p53 function until induced to express p53 [2]. TP53 can...

  15. Paracrine Apoptotic Effect of p53 Mediated by Tumor Suppressor Par-4

    OpenAIRE

    Ravshan Burikhanov; Tripti Shrestha-Bhattarai; Nikhil Hebbar; Shirley Qiu; Yanming Zhao; Gerard P. Zambetti; Vivek M. Rangnekar

    2014-01-01

    The guardian of the genome, p53, is often mutated in cancer and may contribute to therapeutic resistance. Given that p53 is intact and functional in normal tissues, we harnessed its potential to inhibit the growth of p53-deficient cancer cells. Specific activation of p53 in normal fibroblasts selectively induced apoptosis in p53-deficient cancer cells. This paracrine effect was mediated by p53-dependent secretion of the tumor suppressor Par-4. Accordingly, the activation of p53 in normal mice...

  16. In vivo analysis of p53 tumor suppressor function using genetically engineered mouse models

    OpenAIRE

    Brož, Daniela Kenzelmann; Attardi, Laura D.

    2010-01-01

    p53 is a crucial tumor suppressor, as evidenced by the high propensity for p53 mutation during human cancer development. Already more than a decade ago, p53 knockout mice confirmed that p53 is critical for preventing tumorigenesis. More recently, a host of p53 knock-in mouse strains has been generated, with the aim of either more precisely modeling p53 mutations in human cancer or better understanding p53's regulation and downstream activities. In the first category, several mouse strains exp...

  17. A common Gain of function of p53 cancer mutants in inducing genetic instability

    OpenAIRE

    Liu, Dong-Ping; Song, Hoseok; Xu, Yang

    2009-01-01

    The critical tumor suppressor p53 is mutated in over half of all human cancers. The majority of p53 cancer mutations are missense mutations, which can be classified into contact mutations that directly disrupt the DNA-binding motif of p53 but have modest impact on p53 conformation and structural mutations that greatly disrupt p53 conformation. Many p53 cancer mutants, including the hotspot mutations (R175H, R248W and R273H), not only lose p53-dependent tumor suppressor activities, but also ac...

  18. Insights into p53 transcriptional function via genome-wide chromatin occupancy and gene expression analysis

    OpenAIRE

    F Nikulenkov; Spinnler, C; Li, H.; Tonelli, C; Shi, Y; Turunen, M.; Kivioja, T; Ignatiev, I.; Kel, A; Taipale, J; Selivanova, G

    2012-01-01

    The tumor-suppressor p53 can induce various biological responses. Yet, it is not clear whether it is p53 in vivo promoter selectivity that triggers different transcription programs leading to different outcomes. Our analysis of genome-wide chromatin occupancy by p53 using chromatin immunoprecipitation (ChIP)-seq revealed ‘p53 default program', that is, the pattern of major p53-bound sites that is similar upon p53 activation by nutlin3a, reactivation of p53 and induction of tumor cell apoptosi...

  19. Distinguishing Low-Risk Luminal A Breast Cancer Subtypes with Ki-67 and p53 Is More Predictive of Long-Term Survival.

    Directory of Open Access Journals (Sweden)

    Se Kyung Lee

    Full Text Available Overexpression of p53 is the most frequent genetic alteration in breast cancer. Recently, many studies have shown that the expression of mutant p53 differs for each subtype of breast cancer and is associated with different prognoses. In this study, we aimed to determine the suitable cut-off value to predict the clinical outcome of p53 overexpression and its usefulness as a prognostic factor in each subtype of breast cancer, especially in luminal A breast cancer. Approval was granted by the Institutional Review Board of Samsung Medical Center. We analyzed a total of 7,739 patients who were surgically treated for invasive breast cancer at Samsung Medical Center between Dec 1995 and Apr 2013. Luminal A subtype was defined as ER&PR + and HER2- and was further subclassified according to Ki-67 and p53 expression as follows: luminal A (Ki-67-,p53-, luminal A (Ki-67+, p53-, luminal A (Ki-67 -, p53+ and luminal A (Ki-67+, p53+. Low-risk luminal A subtype was defined as negative for both Ki-67 and p53 (luminal A [ki-67-, p53-], and others subtypes were considered to be high-risk luminal A breast cancer. A cut-off value of 10% for p53 was a good predictor of clinical outcome in all patients and luminal A breast cancer patients. The prognostic role of p53 overexpression for OS and DFS was only significant in luminal A subtype. The combination of p53 and Ki-67 has been shown to have the best predictive power as calculated by the area under curve (AUC, especially for long-term overall survival. In this study, we have shown that overexpression of p53 and Ki-67 could be used to discriminate low-risk luminal A subtype in breast cancer. Therefore, using the combination of p53 and Ki-67 expression in discriminating low-risk luminal A breast cancer may improve the prognostic power and provide the greatest clinical utility.

  20. ACTIVATION OF p53 IN DOWN SYNDROME AND IN THE Ts65Dn MOUSE BRAIN IS ASSOCIATED WITH A PRO-APOPTOTIC PHENOTYPE

    Science.gov (United States)

    Di Domenico, Fabio; Barone, Eugenio; Arena, Andrea; Lanzillotta, Chiara; Brokeaart, Diede; Blarzino, Carla; Head, Elizabeth; Butterfield, D Allan; Perluigi, Marzia

    2016-01-01

    Down Syndrome (DS) is the most common genetic cause of intellectual disability resulting from trisomy of chromosome 21. The main feature of DS neuropathology includes early onset of Alzheimer's disease, with deposition of senile plaques and tangles. We hypothesized that apoptosis may be activated in the presence of AD neuropathology in DS, thus we measured proteins associated with upstream and downstream pathways of p53 in the frontal cortex from DS cases with and without AD pathology and from Ts65Dn mice, at different ages. We observed increased acetylation and phosphorylation of p53, coupled to reduced MDM2-mediated ubiquitination and lower levels of SIRT1. Activation of p53 was associated with a number of down-stream targets (bax, PARP1, caspase-3, heat shock proteins and PGC1α) that were modulated in both DS and DS/AD compared with age-matched controls. In particular, the most relevant changes (increased p-p53, acetyl-p53 and reduced formation of MDM2/p53 complex) were found to be modified only in the presence of AD pathology in DS. In addition, a similar pattern of alterations in the p53 pathway were found in Ts65Dn mice. These results suggest that p53 may integrate different signals, which can result in a pro-apoptotic-phenotype contributing to AD neuropathology in people with DS. PMID:26967221

  1. Mutant p53 accumulates in cycling and proliferating cells in the normal tissues of p53 R172H mutant mice.

    Science.gov (United States)

    Goh, Amanda M; Xue, Yuezhen; Leushacke, Marc; Li, Ling; Wong, Julin S; Chiam, Poh Cheang; Rahmat, Siti Aishah Binte; Mann, Michael B; Mann, Karen M; Barker, Nick; Lozano, Guillermina; Terzian, Tamara; Lane, David P

    2015-07-20

    The tumour suppressor p53 is regulated primarily at the protein level. In normal tissues its levels are maintained at a very low level by the action of specific E3 ligases and the ubiquitin proteosome pathway. The mutant p53 protein contributes to transformation, metastasis and drug resistance. High levels of mutant p53 can be found in tumours and the accumulation of mutant p53 has previously been reported in pathologically normal cells in human skin. We show for the first time that similarly elevated levels of mutant p53 can be detected in apparently normal cells in a mutant p53 knock-in mouse model. In fact, in the small intestine, mutant p53 spontaneously accumulates in a manner dependent on gene dosage and cell type. Mutant p53 protein is regulated similarly to wild type p53, which can accumulate rapidly after induction by ionising radiation or Mdm2 inhibitors, however, the clearance of mutant p53 protein is much slower than wild type p53. The accumulation of the protein in the murine small intestine is limited to the cycling, crypt base columnar cells and proliferative zone and is lost as the cells differentiate and exit the cell cycle. Loss of Mdm2 results in even higher levels of p53 expression but p53 is still restricted to proliferating cells in the small intestine. Therefore, the small intestine of these p53 mutant mice is an experimental system in which we can dissect the molecular pathways leading to p53 accumulation, which has important implications for cancer prevention and therapy. PMID:26255629

  2. Adenovirus-mediated p53 and ING4 gene co-transfer elicits synergistic antitumor effects through enhancement of p53 acetylation in breast cancer.

    Science.gov (United States)

    Wu, Jie; Zhu, Yanbo; Xu, Chun; Xu, Hong; Zhou, Xiumin; Yang, Jicheng; Xie, Yufeng; Tao, Min

    2016-01-01

    Multigene-based combination therapy may be an effective practice in cancer gene therapy. Substantial studies have demonstrated that tumor suppressor p53 acetylation is indispensable for p53 activation. Inhibitor of growth 4 (ING4), as a novel tumor suppressor, is capable of remarkably enhancing p53 acetylation and its transcriptional activity. Hence, we assumed that combined treatment of p53 and ING4 double tumor suppressors would exhibit enhanced antitumor effects. The combined therapeutic efficacy of p53 and ING4 for human cancers has not been previously reported. We thus generated multiple promoter expression cassette-based recombinant adenovirus-co-expressing ING4 and p53 double tumor suppressor genes (AdVING4/p53), evaluated the combined effects of AdVING4/p53 on breast cancer using the MDA-MB-231 (mutant p53) human breast cancer cell line, and also elucidated its underlying molecular mechanisms. We demonstrated that AdVING4/p53-mediated p53 and ING4 co-expression induced synergistic growth inhibition and apoptosis as well as enhanced effects on upregulation of acetylated p53, P21, Bax, PUMA, Noxa, cleaved caspase-9, cleaved caspase-3 and cleaved PARP, and downregulation of Bcl-2, CD31 and microvessel density (MVD) in MDA-MB-231 breast cancer in vitro and/or in vivo subcutaneous (s.c.) xenografted tumors. The synergistic antitumor activity elicited by AdVING4/p53 was closely associated with the enhanced activation of the intrinsic apoptotic pathway and synergistic inhibition of tumor angiogenesis, very possibly via ING4-mediated enhancement of p53 acetylation and activity. Thus, our results indicate that cancer gene therapy combining two or more tumor suppressors such as p53 and ING4 may constitute a novel and effective therapeutic modality for human breast cancer and other cancers. PMID:26530780

  3. Suicide genes or p53 gene and p53 target genes as targets for cancer gene therapy by ionizing radiation

    International Nuclear Information System (INIS)

    Radiotherapy has some disadvantages due to the severe side-effect on the normal tissues at a curative dose of ionizing radiation (IR). Similarly, as a new developing approach, gene therapy also has some disadvantages, such as lack of specificity for tumors, limited expression of therapeutic gene, potential biological risk. To certain extent, above problems would be solved by the suicide genes or p53 gene and its target genes therapies targeted by ionizing radiation. This strategy not only makes up the disadvantage from radiotherapy or gene therapy alone, but also promotes success rate on the base of lower dose. By present, there have been several vectors measuring up to be reaching clinical trials. This review focused on the development of the cancer gene therapy through suicide genes or p53 and its target genes mediated by IR. (authors)

  4. Proteasome inhibition mediates p53 reactivation and anti-cancer activity of 6-Gingerol in cervical cancer cells

    Science.gov (United States)

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

    2015-01-01

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

  5. Structural insights into the transcription-independent apoptotic pathway of p53

    OpenAIRE

    Chi, Seung-Wook

    2014-01-01

    Reactivating the p53 pathway in tumors is an important strategy for anticancer therapy. In response to diverse cellular stresses, the tumor suppressor p53 mediates apoptosis in a transcriptionindependent and transcription-dependent manner. Although extensive studies have focused on the transcription-dependent apoptotic pathway of p53, the transcription-independent apoptotic pathway of p53 has only recently been discovered. Molecular interactions between p53 and Bcl-2 family proteins in the mi...

  6. MSL2 Promotes Mdm2-independent Cytoplasmic Localization of p53*

    OpenAIRE

    Kruse, Jan-Philipp; Gu, Wei

    2009-01-01

    Although it was originally thought of as a passive way to block the nuclear function of p53, accumulating evidence suggests that cytoplasmic localization of p53 plays an active role in p53-mediated functions such as apoptosis and autophagy. Previous studies by us and others demonstrated that Mdm2-mediated p53 ubiquitination induces both degradation and cytoplasmic localization. Here we describe MSL2, a novel E3 ligase for p53 that promotes ubiquitin-dependent cytoplasm...

  7. Posttranscriptional Regulation of p53 and Its Targets by RNA-Binding Proteins

    OpenAIRE

    Zhang, Jin; Chen, Xinbin

    2008-01-01

    p53 tumor suppressor plays a pivotal role in maintaining genomic integrity and preventing cancer development. The importance of p53 in tumor suppression is illustrated by the observation that about 50% human tumor cells have a dysfunctional p53 pathway. Although it has been well accepted that the activity of p53 is mainly controlled through post-translational modifications, recent studies have revealed that posttranscriptional regulations of p53 by various RNA-binding proteins also play a cru...

  8. Regulation of p53 Localization and Activity by Ubc13▿ †

    OpenAIRE

    Laine, Aaron; Topisirovic, Ivan; Zhai, Dayong; John C Reed; Borden, Katherine L. B.; Ronai, Ze'ev

    2006-01-01

    The abundance and activity of p53 are regulated largely by ubiquitin ligases. Here we demonstrate a previously undisclosed regulation of p53 localization and activity by Ubc13, an E2 ubiquitin-conjugating enzyme. While increasing p53 stability, Ubc13 decreases p53 transcriptional activity and increases its localization to the cytoplasm, changes that require its ubiquitin-conjugating activity. Ubc13 elicits K63-dependent ubiquitination of p53, which attenuates Hdm2-induced polyubiquitination o...

  9. Tumor suppressor p53 and its gain-of-function mutants in cancer

    OpenAIRE

    Liu, Juan; Zhang, Cen; Feng, Zhaohui

    2013-01-01

    Tumor suppressor p53 plays a pivotal role in tumor suppression. p53 is the most frequently mutated gene in cancer. As a transcription factor, p53 mainly exerts its role in tumor suppression through transcriptional regulation of its downstream target genes. Thus, p53 and its target genes form a complex p53 signaling pathway to regulate a wide variety of biological processes to prevent tumorigenesis. Recent studies have revealed that in addition to apoptosis, cell cycle arrest and senescence, p...

  10. Gene expression profiles resulting from stable loss of p53 mirrors its role in tissue differentiation.

    Directory of Open Access Journals (Sweden)

    Oliver Couture

    Full Text Available The tumor suppressor gene p53 is involved in a variety of cellular activities such as cellular stress responses, cell cycle regulation and differentiation. In our previous studies we have shown p53's transcription activating role to be important in osteoblast differentiation. There is still a debate in the literature as to whether p53 inhibits or promotes differentiation. We have found p53 heterozygous mice to show a p53 dependency on some bone marker gene expression that is absent in knockout mice. Mice heterozygous for p53 also show a higher incidence of osteosarcomas than p53 knockout mice. This suggests that p53 is able to modify the environment within osteoblasts. In this study we compare changes in gene expression resulting after either a transient or stable reduction in p53. Accordingly we reduced p53 levels transiently and stably in C2C12 cells, which are capable of both myoblast and osteoblast differentiation, and compared the changes in gene expression of candidate genes regulated by the p53 pathway. Using a PCR array to assay for p53 target genes, we have found different expression profiles when comparing stable versus transient knockdown of p53. As expected, several genes with profound changes after transient p53 loss were related to apoptosis and cell cycle regulation. In contrast, stable p53 loss produced a greater change in MyoD and other transcription factors with tissue specific roles, suggesting that long term loss of p53 affects tissue homeostasis to a greater degree than changes resulting from acute loss of p53. These differences in gene expression were validated by measuring promoter activity of different pathway specific genes involved in differentiation. These studies suggest that an important role for p53 is context dependent, with a stable reduction in p53 expression affecting normal tissue physiology more than acute loss of p53.

  11. A nanobody modulates the p53 transcriptional program without perturbing its functional architecture

    OpenAIRE

    Bethuyne, Jonas; De Gieter, Steven; Zwaenepoel, Olivier; Garcia-Pino, Abel; Durinck, Kaat; Verhelle, Adriaan; Hassanzadeh-Ghassabeh, Gholamreza; Speleman, Franki; Loris, Remy; Gettemans, Jan

    2014-01-01

    The p53 transcription factor plays an important role in genome integrity. To perform this task, p53 regulates the transcription of genes promoting various cellular outcomes including cell cycle arrest, apoptosis or senescence. The precise regulation of this activity remains elusive as numerous mechanisms, e.g. posttranslational modifications of p53 and (non-)covalent p53 binding partners, influence the p53 transcriptional program. We developed a novel, non-invasive tool to manipulate endogeno...

  12. Mutational myriad of tumor suppressor p53 in Filipino breast cancer: results and perspectives in molecular pathology and epidemiology

    International Nuclear Information System (INIS)

    The p53 tumor suppressor is by far the most widely mutated gene in human cancers. p53 encodes a 53-kDa phosphoprotein, transcription-activator whose targets include genes and gene products that orchestrate genomic stability, cellular response to DNA damage, cell cycle progression apoptosis and aging (senescence). Analysis of the p53 gene profile has previously resulted in identifying several cancer-causative factors in the human setting, as well as, in creating a unique molecular profile of a tumor useful in the design of tailored-therapies for individual cancer patients. Our results in screening for p53 abnormalities in 140 Filipino patients with primary breast lesions confined from 1997-1998 in 5 major hospitals in Manila reveal that p53 plays an important role in the development and progression of breast cancer in at least 48% of all cases. Two methods of p53 analysis are employed, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction-temporal temperature gradient electrophoresis (PCR-TTGE). Inter-comparisons of method exhibit 63.3% concordance in 21 fresh breast carcinoma samples, with ELISA demonstrating 14% false-positives and 10% false-negatives. Only mutations in exon 7 (p=0.063) in the tumor samples how significant correlation with abnormal cellular elevation of p53. PCR-TTGE screening in a large series of 140 patients show that most genetic lesions are localized in exons 5 (41% of the total cases) and 6 (27% of the total cases). No mutations are, however, detected in the transactivation (exons 2-4) and oligomerization (exons 10-11) domains. Invasive carcinomas (stages II and III) are characterized with more frequent and diverse genetic alterations compared with benign tumors, most significantly at exon 5B (p=0.066) and at independently multiple sites (p=0.066). Earlier-onset cases (age of diagnosis < 50 yrs), known to be more clinico-pathologically aggressive, are diagnosed harboring more frequent p53 mutations centered at exon 7 (p=0

  13. Transcriptional Regulation of Breast Cancer Resistance Protein (BCRP) by p53 in p53-null Saos-2 cells%p53对乳腺癌耐药蛋白基因的转录调控

    Institute of Scientific and Technical Information of China (English)

    吴新刚; 彭姝彬; 闾四平; 张年凤; 邹进

    2012-01-01

    Breast cancer resistance protein (BCRP) is a member of the ATP-binding cassette (ABC) transporter superfamily. BCRP confers drug resistance in cancer by transporting chemotherapeutic agents such as mitoxantrone, topotecan, and methotrexate. Although a recent study demonstrated that wild type p53 (wt-p53) may suppress BCRP expression through the nuclear factor-KB (NF-kB) pathway in breast cancer cell line MCF-7, which expresses wt-p53 at low level, the detailed molecular mechanisms of transcriptional regulation on BCRP remain unclear. Here, we set out to reveal the exogenous p53's role on the expression of BCRP. In the human osteosarcoma cell line Saos-2, a p53-null cell line, transient transfection assays showed that the BCRP expression was activated by wt-p53 but not p53 mutants, p53R175H and p53R248W. We further co-transfected the p53 expression plasmid with BCRP luciferasepromoter reporter construct into the Saos-2 cell, and the results revealed that wt-p53 may facilitate the BCRP promoter activity. However, we did not find any p53 binding site by applying Matlnspector. Strikingly, NF-kB activity inhibition downplayed the activation effect of BCRP promoter activity by wt-p53. These results suggested that transcriptional activation of BCRP by wt-p53 is NF-kB- dependent.%乳腺癌耐药蛋白(breast cancer resistance protein,BCRP)是ATP结合盒转运蛋白超家族成员之一,其通过主动外排化疗药物如米托蒽醌、托泊替康和甲氨蝶呤,进而介导肿瘤化疗耐受.最近有研究发现,在野生型p53 (wild type p53,wt-p53)低表达的乳腺癌细胞系MCF-7中,外源性wt-p53通过抑制核转录因子-κB (nuclear factor-κB,NF-κB)的活性进而抑制BCRP的表达,但其详细的分子机制有待进一步阐明.本研究选用p53缺失的骨肉瘤细胞系Saos-2,通过瞬时转染技术发现,wt-p53可以激活BCRP的表达,而突变型p53的激活作用消失;报告基因试验显示,wt-p53可以上调BCRP启动子活性;通过生

  14. High-level expression of wild-type p53 in melanoma cells is frequently associated with inactivity in p53 reporter gene assays.

    Directory of Open Access Journals (Sweden)

    Roland Houben

    Full Text Available BACKGROUND: Inactivation of the p53 pathway that controls cell cycle progression, apoptosis and senescence, has been proposed to occur in virtually all human tumors and p53 is the protein most frequently mutated in human cancer. However, the mutational status of p53 in melanoma is still controversial; to clarify this notion we analysed the largest series of melanoma samples reported to date. METHODOLOGY/PRINCIPAL FINDINGS: Immunohistochemical analysis of more than 180 melanoma specimens demonstrated that high levels of p53 are expressed in the vast majority of cases. Subsequent sequencing of the p53 exons 5-8, however, revealed only in one case the presence of a mutation. Nevertheless, by means of two different p53 reporter constructs we demonstrate transcriptional inactivity of wild type p53 in 6 out of 10 melanoma cell lines; the 4 other p53 wild type melanoma cell lines exhibit p53 reporter gene activity, which can be blocked by shRNA knock down of p53. CONCLUSIONS/SIGNIFICANCE: In melanomas expressing high levels of wild type p53 this tumor suppressor is frequently inactivated at transcriptional level.

  15. The role of p53 tumor suppressor gene in the suppression of teratogenesis. Mechanism of suppression in the embryonic stage by p53-dependent apoptosis

    International Nuclear Information System (INIS)

    This review described the relationships between radiation-induced teratogenesis in the embryonic stage and p53-dependent apoptosis together with recent authors' findings. The p53 tumor suppressor gene in the embryonic and fetal stages: Thymocytes deficient of p53 gene are markedly resistant to radiation. While the survival rate of wild type cells decreased at 1 Gy irradiation, that of the deficient cells hardly changed even at 20 Gy. Starting from these facts, the role of p53 gene in the teratogenesis has been investigated with use of radiation-irradiated wild type and p53-deficient knock-out mice and of mdm2/p53 double knock-out mice. Types of malformation yielded were described. The relationships between radiation-induced teratogenesis and p53 in mouse fetus: Authors performed the following experiment in the p53 knock-out mice to elucidate how p53 participated in the radiation-induced teratogenesis: X-ray at 1 and 2 Gy (250 kVp, 12 mA, 0.5 mm Cu + 1.0 mm Al) was irradiated to the recipient mice at 3.5 days (early nidation) or 9.5 days (organogenesis) of gestation. Malformation in the alive and dead fetuses was observed at 18.5 days and classified according to the p53 genotype. The teratogenesis due to chemicals and radiation in p53 gene deficient mice was discussed. (K.H.)

  16. Escape from p53-mediated tumor surveillance in neuroblastoma: switching off the p14(ARF)-MDM2-p53 axis.

    Science.gov (United States)

    Van Maerken, T; Vandesompele, J; Rihani, A; De Paepe, A; Speleman, F

    2009-12-01

    A primary failsafe program against unrestrained proliferation and oncogenesis is provided by the p53 tumor suppressor protein, inactivation of which is considered as a hallmark of cancer. Intriguingly, mutations of the TP53 gene are rarely encountered in neuroblastoma tumors, suggesting that alternative p53-inactivating lesions account for escape from p53 control in this childhood malignancy. Several recent studies have shed light on the mechanisms by which neuroblastoma cells circumvent the p53-driven antitumor barrier. We review here these mechanisms for evasion of p53-mediated growth control and conclude that deregulation of the p14(ARF)-MDM2-p53 axis seems to be the principal mode of p53 inactivation in neuroblastoma, opening new perspectives for targeted therapeutic intervention. PMID:19779493

  17. 结肠癌组织中P53基因及其产物变化的研究%Mutation of P53 Gene and Expression of P53 Protein in Colon Cancer

    Institute of Scientific and Technical Information of China (English)

    张玉敏; 尹德霞; 朱桂钱

    2001-01-01

    目的 探索P53基因突变在结肠癌发生过程中的作用.方法应用多聚酶链反应-单纯构象多态分析及免疫组化ABC法研究结肠癌组织中的P53基因及其产物蛋白质的变化.结果结肠癌中有45%发生P53基因突变,52.50% P53蛋白阳性;所获数据经χ2检验.结论对P53基因突变和P53蛋白的检测可作为判断结肠癌生物学行为的重要标志.

  18. DNA damage induces p53-dependent BRCA1 nuclear export

    International Nuclear Information System (INIS)

    Full text: Carriers of BRCA1 mutations have an 85% risk of developing breast cancer by age 70. This risk is about 20-fold higher than the general population. BRCA1 functions in multiple DNA damage response pathways, and its functions are regulated by a variety of mechanisms including transcription control, phosphorylation, and protein-protein interactions. Given the critical role of BRCA1 in nucleus, its sub-cellular localization could be an important mechanism in regulating its function. Recent studies showed that BRCA1 is a nuclear-cytoplasmic shuttle protein. It is imported to the nucleus through a nuclear localization signal (NLS)-mediated importing receptor pathway, and exported to cytoplasm via a nuclear export signal (NES)-facilitated CRM1 pathway. However, little is known on how BRCA1 shuttling between the nucleus and cytoplasm is controlled, what cellular process(s) or environmental insult(s) triggers cell to import BRCA1 protein to nucleus and verse visa. In view of the fact that BRCA1 plays critical roles in several DNA damage response pathways, we hypothesized that ionizing radiation-induced DNA damage may affect BRCA1 shuttling. We found that ionizing radiation-induced DNA damage promotes BRCA1 nuclear export in human breast cancer cells through a CRM1-dependent mechanism. We further found that DNA damage-induced BRCA1 nuclear export is dependent on wild-type p53 function. These results suggest that p53-dependent BRCA1 nucleus export might be an alternative mechanism for BRCA1 functional regulation in cellular response to DNA damage. Interruption of BRCA1 shuttling in breast cancer cells that do not have functional p53 may compromise the precise regulation of BRCA1 function timely and spatially, resulting in aberrant DNA repair and increased genetic instability in surviving cells

  19. Transient transfection of a wild-type p53 gene triggers resveratrol-induced apoptosis in cancer cells.

    Science.gov (United States)

    Ferraz da Costa, Danielly Cristiny; Casanova, Fabiana Alves; Quarti, Julia; Malheiros, Maitê Santos; Sanches, Daniel; Dos Santos, Patricia Souza; Fialho, Eliane; Silva, Jerson L

    2012-01-01

    Resveratrol is a promising chemopreventive agent that mediates many cellular targets involved in cancer signaling pathways. p53 has been suggested to play a role in the anticancer properties of resveratrol. We investigated resveratrol-induced cytotoxicity in H1299 cells, which are non-small lung cancer cells that have a partial deletion of the gene that encodes the p53 protein. The results for H1299 cells were compared with those for three cell lines that constitutively express wild-type p53: breast cancer MCF-7, adenocarcinomic alveolar basal epithelia A549 and non-small lung cancer H460. Cell viability assays revealed that resveratrol reduced the viability of all four of these cell lines in a dose- and time-dependent manner. MCF-7, A549 and H460 cells were more sensitive to resveratrol than were H1299 cells when exposed to the drug for 24 h at concentrations above 100 µM. Resveratrol also increased the p53 protein levels in MCF-7 cells without altering the p53 mRNA levels, suggesting a post-translational modulation of the protein. The resveratrol-induced cytotoxicity in these cells was partially mediated by p53 and involved the activation of caspases 9 and 7 and the cleavage of PARP. In H1299 cells, resveratrol-induced cytotoxicity was less pronounced and (in contrast to MCF-7 cells) cell death was not accompanied by caspase activation. These findings are consistent with the observation that MCF-7 cells were positively labeled by TUNEL following exposure to 100 µM resveratrol whereas H1299 cells under similar conditions were not labeled by TUNEL. The transient transfection of a wild-type p53-GFP gene caused H1299 cells to become more responsive to the pro-apoptotic properties of resveratrol, similarly to findings in the p53-positive MCF-7 cells. Our results suggest a possible therapeutic strategy based on the use of resveratrol for the treatment of tumors that are typically unresponsive to conventional therapies because of the loss of normal p53 function. PMID

  20. Transient transfection of a wild-type p53 gene triggers resveratrol-induced apoptosis in cancer cells.

    Directory of Open Access Journals (Sweden)

    Danielly Cristiny Ferraz da Costa

    Full Text Available Resveratrol is a promising chemopreventive agent that mediates many cellular targets involved in cancer signaling pathways. p53 has been suggested to play a role in the anticancer properties of resveratrol. We investigated resveratrol-induced cytotoxicity in H1299 cells, which are non-small lung cancer cells that have a partial deletion of the gene that encodes the p53 protein. The results for H1299 cells were compared with those for three cell lines that constitutively express wild-type p53: breast cancer MCF-7, adenocarcinomic alveolar basal epithelia A549 and non-small lung cancer H460. Cell viability assays revealed that resveratrol reduced the viability of all four of these cell lines in a dose- and time-dependent manner. MCF-7, A549 and H460 cells were more sensitive to resveratrol than were H1299 cells when exposed to the drug for 24 h at concentrations above 100 µM. Resveratrol also increased the p53 protein levels in MCF-7 cells without altering the p53 mRNA levels, suggesting a post-translational modulation of the protein. The resveratrol-induced cytotoxicity in these cells was partially mediated by p53 and involved the activation of caspases 9 and 7 and the cleavage of PARP. In H1299 cells, resveratrol-induced cytotoxicity was less pronounced and (in contrast to MCF-7 cells cell death was not accompanied by caspase activation. These findings are consistent with the observation that MCF-7 cells were positively labeled by TUNEL following exposure to 100 µM resveratrol whereas H1299 cells under similar conditions were not labeled by TUNEL. The transient transfection of a wild-type p53-GFP gene caused H1299 cells to become more responsive to the pro-apoptotic properties of resveratrol, similarly to findings in the p53-positive MCF-7 cells. Our results suggest a possible therapeutic strategy based on the use of resveratrol for the treatment of tumors that are typically unresponsive to conventional therapies because of the loss of normal

  1. Research advances on the p53 gene network%p53基因调控网络研究进展

    Institute of Scientific and Technical Information of China (English)

    舒坤贤; 王光利; 邬力祥

    2008-01-01

    肿瘤抑制基因p53表达的p53蛋白是一个通用转录因子,与其上、下游功能相关基因组成了一个复杂的基因调控网络,在这个基因网络中p53基因起着关键作用;DNA损伤、缺氧、原癌基因的激活等均能刺激p53基因表达;p53表达升高后,可通过p53-MDM2反馈环路与泛素系统等对p53表达水平进行精确调节;p53通过调控多种下游/靶基因表达完成多种生物学功能,主要包括阻滞细胞周期、促进细胞凋亡、维持基因组稳定性等;认识p53基因调控网络的功能有助于理解p53及其下游/靶基因间的具体作用机制.

  2. DEC1, a Basic Helix-Loop-Helix Transcription Factor and a Novel Target Gene of the p53 Family, Mediates p53-dependent Premature Senescence*

    Science.gov (United States)

    Qian, Yingjuan; Zhang, Jin; Yan, Bingfang; Chen, Xinbin

    2014-01-01

    Cellular senescence plays an important role in tumor suppression. p53 tumor suppressor has been reported to be crucial in cellular senescence. However, the underlying mechanism is poorly understood. In this regard, a cDNA microarray assay was performed to identify p53 targets involved in senescence. Among the many candidates is DEC1, a basic helix-loop-helix transcription factor that has been recently shown to be up-regulated in K-ras-induced premature senescence. However, it is not clear whether DEC1 is capable of inducing senescence. Here, we found that DEC1 is a novel target gene of the p53 family and mediates p53-dependent premature senescence. Specifically, we showed that DEC1 is induced by the p53 family and DNA damage in a p53-dependent manner. We also found that the p53 family proteins bind to, and activate, the promoter of the DEC1 gene. In addition, we showed that overexpression of DEC1 induces G1 arrest and promotes senescence. Moreover, we found that targeting endogenous DEC1 attenuates p53-mediated premature senescence in response to DNA damage. Furthermore, overexpression of DEC1 induces cellular senescence in p53-knockdown cells, albeit to a lesser extent. Finally, we showed that DEC1-induced senescence is p21-independent. Taken together, our data provided strong evidence that DEC1 is one of the effectors downstream of p53 to promote premature senescence. PMID:18025081

  3. Inhibition of p53 transcriptional activity by human cytomegalovirus UL44.

    Science.gov (United States)

    Kwon, Yejin; Kim, Mi-Na; Young Choi, Eun; Heon Kim, Jung; Hwang, Eung-Soo; Cha, Chang-Yong

    2012-05-01

    Human cytomegalovirus (HCMV) stimulates cellular synthesis of DNA and proteins and induces transition of the cell cycle from G(1) to S and G(2) /M phase, in spite of increased amounts of p53 in the infected cells. The immediate early protein IE2-86  kDa (IE86) tethers a transcriptional repression domain to p53; however, its repression of p53 function is not enough to abrogate the G(1) checkpoint function of p53. Other HCMV proteins that suppress the activity of p53 were investigated in this study. Of the HCMV proteins that bind to p53 when assessed by immunoprecipitation and immunoblot analysis, HCMV UL44 was chosen as a candidate protein. It was found that reporter gene containing p53 consensus sequence was activated by transfection with wild type p53, but when plasmids of p53 with IE86 or UL44 were co-transfected, p53 transcriptional activity was decreased to 3-7% of the p53 control in a dose-dependent manner. When the deletion mutant of UL44 was co-transected with p53, the carboxyl one-third portion of UL44 had little effect on inhibition of p53 transcriptional activity. The amount of mRNA p21 was measured in H1299 by real time PCR after transfection of the combination of p53 and UL44 vectors and it was found that p21 transcription by p53 was inhibited dose-dependently by UL44. Increased G0/G1 and decreased S phases in p53 wild type-transfected H1299 cells were recovered to the level of p53 mutant type-transfected ones by the additional transfection of UL44 in a dose-dependent manner. In conclusion, the transcriptional activity of p53 is suppressed by UL44 as well as by IE86. PMID:22376288

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

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shi-Wei [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Wu, Chun-Ying [Division of Gastroenterology and Hepatology, Taichung Veterans General Hospital, Taichung, Taiwan (China); Wang, Yen-Ting [Department of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan (China); Kao, Jun-Kai [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Department of Pediatrics, Children' s Hospital, Changhua Christian Hospital, Changhua, Taiwan (China); Lin, Chi-Chen; Chang, Chia-Che; Mu, Szu-Wei; Chen, Yu-Yu [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Chiu, Husan-Wen [Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan (China); Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan (China); Chang, Chuan-Hsun [Department of Surgical Oncology, Cheng Hsin General Hospital, Taipei, Taiwan (China); Department of Nutrition Therapy, Cheng Hsin General Hospital, Taipei, Taiwan (China); School of Nutrition and Health Sciences, Taipei Medical University, Taipei, Taiwan (China); Liang, Shu-Mei [Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan (China); Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan (China); Chen, Yi-Ju [Department of Dermatology, Taichung Veterans General Hospital, Taichung, Taiwan (China); Huang, Jau-Ling [Department of Bioscience Technology, Chang Jung Christian University, Tainan, Taiwan (China); Shieh, Jeng-Jer, E-mail: shiehjj@vghtc.gov.tw [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan (China)

    2013-02-15

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

  5. The antagonism between MCT-1 and p53 affects the tumorigenic outcomes

    Directory of Open Access Journals (Sweden)

    Lin Tai-Du

    2010-12-01

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

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

    International Nuclear Information System (INIS)

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

  7. Shifting p53-induced senescence to cell death by TIS21(/BTG2/Pc3) gene through posttranslational modification of p53 protein.

    Science.gov (United States)

    Choi, Ok Ran; Ryu, Min Sook; Lim, In Kyoung

    2016-09-01

    Cellular senescence and apoptosis can be regulated by p53 activity, although the underlying mechanism of the switch between the two events remains largely unknown. Cells exposed to cancer chemotherapy can escape to senescence phenotype rather than undergoing apoptosis. By employing adenoviral transduction of p53 or TIS21 genes, we observed shifting of p53 induced-senescence to apoptosis in EJ bladder cancer cells, which express H-RasV12 and mutant p53; transduction of p53 increased H-RasV12 expression along with senescence phenotypes, whereas coexpression with TIS21 (p53+TIS21) induced cell death rather than senescence. The TIS21-mediated switch of senescence to apoptosis was accompanied by nuclear translocation of p53 protein and its modifications on Ser-15 and Ser-46 phosphorylation and acetylations on Lys-120, -320, -373 and -382 residues. Mechanistically, TIS21(/BTG2) regulated posttranslational modification of p53 via enhancing miR34a and Bax expressions as opposed to inhibiting SIRT1 and Bcl2 expression. At the same time, TIS21 increased APAF-1 and p53AIP1 expressions, but inhibited the interaction of p53 with iASPP. In vitro tumorigenicity was significantly reduced in the p53+TIS21 expresser through inhibiting micro-colony proliferation by TIS21. Effect of TIS21 on the regulation of p53 activity was confirmed by knockdown of TIS21 expression by RNA interference. Therefore, we suggest TIS21 expression as an endogenous cell death inducer at the downstream of p53 gene, which might be useful for intractable cancer chemotherapy. PMID:27208501

  8. Mutant p53 and ETS2, a Tale of Reciprocity.

    Science.gov (United States)

    Martinez, Luis Alfonso

    2016-01-01

    TP53 is one of the most frequently inactivated tumor suppressor genes in human cancer. However, unlike other tumor suppressor genes whose expression is lost, TP53 is usually inactivated as a result of a single nucleotide change within the coding region. Typically, these single nucleotide mutations result in a codon change that creates an amino acid substitution. Thus, unlike other tumor suppressor genes whose expression is lost due to genetic or epigenetic changes, the p53 gene primarily suffers missense mutations, and therefore, the cells retain and express a mutant form of the p53 protein (mtp53). It is now well established that mtp53 contributes to tumor development through its gain-of-function (GOF) activities. These GOF activities can arise from novel protein-protein interactions that can either disable other tumor suppressors (e.g., p63 and p73) or enable oncogenes such as ETS2, an ETS family member. In this review, I will focus on the identification of the mtp53/ETS2 complex and outline the diverse activities that this transcriptional regulatory complex controls to promote cancer. PMID:26925389

  9. Potential role and chronology of abnormal expression of the Deleted in Colon Cancer (DCC) and the p53 proteins in the development of gastric cancer

    International Nuclear Information System (INIS)

    Loss of activity of tumor suppressor genes is considered a fundamental step in a genetic model of carcinogenesis. Altered expression of the p53 and the Deleted in Colon Cancer (DCC) proteins has been described in gastric cancer and this event may have a role in the development of the disease. According to this hypothesis, we investigated the p53 and the DCC proteins expression in different stages of gastric carcinomas. An immunohistochemical analysis for detection of p53 and DCC proteins expression was performed in tumor tissue samples of patients with UICC stage I and II gastric cancer. For the purpose of the analysis, the staining results were related to the pathologic data and compared between stage categories. Ninety-four cases of gastric cancer were analyzed. Disease stage categories were pT1N0 in 23 cases, pT2N0 in 20 cases, pT3N0 in 20 cases and pT1-3 with nodal involvment in 31 cases. Stage pT1-2N0 tumors maintained a positive DCC expression while it was abolished in pT3N0 tumors (p <.001). A significant higher proportion of patients with N2 nodal involvement showed DCC negative tumors. In muscular-invading tumors (pT2-3N0) the majority of cases showed p53 overexpression, whereas a significantly higher proportion of cases confined into the mucosa (pT1N0) showed p53 negative tumors. Also, a higher frequency of p53 overexpression was detected in cases with N1 and N2 metastatic lymphnodal involvement. Altered expression of both DCC and p53 proteins is detectable in gastric carcinomas. It seems that loss of wild-type p53 gene function and consequent p53 overexpression may be involved in early stages of tumor progression while DCC abnormalities are a late event

  10. Construction and application of mouse PLJM1-p53-GFP plasmid%p53基因真核表达质粒PLJM1-p53-GFP构建及其应用

    Institute of Scientific and Technical Information of China (English)

    朱伟东; 辛婧; 周苏明; 沈捷; 杜新丽; 张日华; 刘云

    2012-01-01

    Objective:To construct PLJM1-p53-GFP plasmid of mouse p53 gene and study the role of p53 in the prostate cancer cells PC3. Methods:The open reading frame (ORF) of mouse p53 gene was amplified from mouse 3T3-L1 cells by RT-PCR,and inserted into the PLJM1-NRG1-GFP vector. The recombinant plasmid was transformed into DH5a competent E. coli. The positive clones were screened by PCR and the inserts were confirmed by DNA sequencing. The PLJM1-p53-GFP plasmid was transfected into the prostate cancer cells PC3. QPCR was used to detect the efficiency of the transfection. The invasive activity and proliferation of PC3 cells were measured after transfecting the PLJM1-p53-GFP plasmid. Results:DNA sequencing demonstrated that the recombinant plasmid PLJMl-p53-GFP was constructed successfully. The invasive activity and proliferation of PC3 cells were obviously decreased after transfection of the PLJM1-p53-GFP plasmid. Conclusion: The plasmid of PLJM1-p53-GFP of mouse p53 gene was successfully constructed. It can be used in the functional research for cancer.%目的:构建小鼠p53基因真核表达质粒PLJM1-p53-GFP,研究其对前列腺癌细胞株PC3侵袭、增殖能力的影响.方法:从小鼠3T3-L1细胞提取总RNA,经RT-PCR获得cDNA,扩增p53基因,经酶切纯化后的产物与双酶切后的PLJM1-NRG1-GFP慢病毒载体连接,得到PLJM1-p53-GFP慢病毒载体并转化感受态细菌DH5α,通过PCR筛选阳性克隆,抽提质粒并测序鉴定.将PLJM1-p53-GFP质粒瞬时转染到PC3细胞中,提取RNA,定量PCR鉴定p53高表达水平,采用细胞侵袭实验观察高表达p53的前列腺癌细胞株PC3的侵袭能力,采用流式细胞及划痕试验研究p53对前列腺癌细胞株PC3增殖活性的影响.结果:测序证实,目的基因p53插入完全正确且无任何突变;高表达p53的PC3细胞的侵袭能力、增殖能力明显下降.结论:成功构建小鼠p53基因真核表达质粒PLJM1-p53-GFP,为深入研究肿瘤等相关疾病提供了有效的工具.

  11. Effect of tumor necrosis factor alpha on mutant p53 protein expression in colorectal cancer cell lines%肿瘤坏死因子alpha上调人结肠癌细胞株突变型p53蛋白的表达

    Institute of Scientific and Technical Information of China (English)

    包成梅; 毕大鹏; 周德明

    2011-01-01

    Objectives: To evaluate the effect of TNF-alpha on mutant p53 expression in colorectal cancer cell lines. Methods: The cell lines HT-29 (which expresses mutant p53) and HCT116 (which expresses wild-type p53) were stimulated with TNF-alpha at different concentrations. Immunofluorescence and real-time quantitative RT-PCR were performed to detect the alterations of p53 protein and transcripts. Results: Immunofluorescence indicated that TNF-alpha can markedly induce nuclear p53 protein expression in HT-29 cells; in contrast, the effect of TNF-alpha on p53 expression in HCT116 cells was minimal. Real-time quantitative RT-PCR showed no substantial change of p53 mRNA in HT-29 or HCT116 cells after stimulation with TNF-atpha. Conclusions: TNF-alpha can dramatically induce nuclear mutant p53 protein expression in HT-29 cell line which expresses mutant p53, and this induction wasn't ascribed to the transcription upregulation But this p53-induction effect of TNF-alpha was minimal in HCT116 cell line which expresses wild-type p53. Our findings suggest that TNF-alpha may be a risk factor in the carcinogenesis of IBD patients carrying a p53 mutation.%目的:研究TNF-alpha对人结肠癌细胞株HT-29及HCT116 p53表达的影响.方法:给予人结肠癌细胞株HT-29(表达突变型p53蛋白)及HCT116(表达野生型p53蛋白)不同浓度的TNF-alpha刺激后,应用细胞免疫荧光及实时荧光定量PCR检测突变型p53蛋白表达及p53 mRNA水平的改变.结果:免疫荧光显示TNF-alpha刺激后能显著提高HT-29细胞核突变型p53蛋白的表达(P<0.05),而对表达野生型p53的HCT116的p53水平无明显改变.实时荧光定量PCR结果表明TNF-alpha刺激对HT-29及HCT-116的p53 mRNA水平无明显改变.结论:TNF-alpha能显著上调HT-29突变型p53蛋白的表达,但是该上调作用并不是发生于转录水平.TNF-alpha刺激对表达野生型p53的HCT116细胞株p53水平无明显改变.

  12. The p53 tumour suppressor protein is phosphorylated at serine 389 by casein kinase II.

    OpenAIRE

    Meek, D W; Simon , S; Kikkawa, U; Eckhart, W

    1990-01-01

    The entire coding sequence of wild-type mouse p53 was expressed in Escherichia coli under control of the PL promoter of bacteriophage lambda. The bacterial p53 protein had identical mobility to p53 from SV3T3 cells on SDS polyacrylamide gels and was recognized in bacterial lysates by three p53-specific monoclonal antibodies, including PAb246 which is specific for wild-type mouse p53. Immunoprecipitates of the bacterial p53 were phosphorylated by a highly purified preparation of rat casein kin...

  13. The “Two faces” of Tumor Suppressor p53-revisited

    OpenAIRE

    Smith, Martin L.; Kumar, M.A. Suresh

    2010-01-01

    About 15 years ago, several groups including ours had used matched pairs of cell lines carrying wild type or mutant p53 genes to ascertain a role for p53 in cell survival. These were isogenic cell lines differing only by p53 status. The trend at that time was to support p53-mediated apoptosis. Accordingly, p53-wildtype cells were sensitive to DNA damage compared to p53-mutant cells which were thought to evade apoptosis. However, this finding was not universal. In particular, after UV-radiatio...

  14. Abrogation of the Transactivation Activity of p53 by BCCIP Down-regulation*

    OpenAIRE

    Meng, Xiangbing; Yue, Jingyin; Liu, Zhihe; Shen, Zhiyuan

    2006-01-01

    The tumor suppression function of p53 is mostly conferred by its transactivation activity, which is inactivated by p53 mutations in ~50% of human cancers. In cancers harboring wild type p53, the p53 transactivation activity may be compromised by other mechanisms. Identifying the mechanisms by which wild type p53 transactivation activity can be abrogated may provide insights into the molecular etiology of cancers harboring wild type p53. In this report, we show that BCCIP, a BRCA2 and CDKN1A-i...

  15. Illuminating p53 function in cancer with genetically engineered mouse models

    OpenAIRE

    Garcia, Patty B.; Attardi, Laura D.

    2014-01-01

    The key role of the p53 protein in tumor suppression is highlighted by its frequent mutation in human cancers and by the completely penetrant cancer predisposition of p53 null mice. Beyond providing definitive evidence for the critical function of p53 in tumor suppression, genetically engineered mouse models have offered numerous additional insights into p53 function. p53 knock-in mice expressing tumor-derived p53 mutants have revealed that these mutants display gain-of-function activities th...

  16. Negative Regulation-Resistant p53 Variant Enhances Oncolytic Adenoviral Gene Therapy

    OpenAIRE

    Koo, Taeyoung; Choi, Il-Kyu; Kim, Minjung; Lee, Jung-Sun; Oh, Eonju; Kim, Jungho; Yun, Chae-Ok

    2012-01-01

    Intact p53 function is essential for responsiveness to cancer therapy. However, p53 activity is attenuated by the proto-oncoprotein Mdm2, the adenovirus protein E1B 55kD, and the p53 C-terminal domain. To confer resistance to Mdm2, E1B 55kD, and C-terminal negative regulation, we generated a p53 variant (p53VPΔ30) by deleting the N-terminal and C-terminal regions of wild-type p53 and inserting the transcriptional activation domain of herpes simplex virus VP16 protein. The oncolytic adenovirus...

  17. Tumor protein translationally controlled 1 is a p53 target gene that promotes cell survival

    OpenAIRE

    Chen, Weimin; Wang, Huihui; Tao, Shasha; Zheng, Yi; Wu, Wei; Lian, Fangru; Jaramillo, Melba; Fang, Deyu; Zhang, Donna D.

    2013-01-01

    Tumor suppressor p53 maintains genome stability by differentially activating target genes that control diverse cellular responses, such as the antioxidant response, cell cycle arrest and apoptosis. Despite the fact that many p53 downstream genes have been well characterized, novel p53 target genes are continuously being identified. Here, we report that Tpt1 is a direct target gene of p53. We found that p53 upregulates the transcription of Tpt1 and identified a p53-responsive element in the pr...

  18. p53 binding to human genome: crowd control navigation in chromatin context

    OpenAIRE

    Botcheva, Krassimira

    2014-01-01

    p53 is the most studied human protein because of its role in maintaining genomic stability. Binding to genomic targets is essential for transcription-dependent p53 tumor suppression, but how p53 selects targets remains unclear. Here, the impact of chromatin context on p53 genome-wide binding and targets selection is discussed. It is proposed that p53 genomic binding serves not only to regulate transcription, but to sense epigenomic changes threatening the genomic integrity. The problem of p53...

  19. CLCA2, a target of the p53 family, negatively regulates cancer cell migration and invasion

    OpenAIRE

    Sasaki, Yasushi; Koyama, Ryota; Maruyama, Reo; Hirano, Takehiro; Tamura, Miyuki; Sugisaka, Jun; Suzuki, Hiromu; Idogawa, Masashi; Shinomura, Yasuhisa; Tokino, Takashi

    2012-01-01

    The tumor suppressor p53 transcriptionally regulates a number of genes that are involved in cell-cycle inhibition, apoptosis and the maintenance of genetic stability. Recent studies suggest that p53 also contributes to the regulation of cell migration and invasion. Here, we show that human chloride channel accessory-2 (CLCA2) is a target gene of the p53 family (p53, p73 and p63). CLCA2 is induced by DNA damage in a p53-dependent manner. The p53 family proteins activate the CLCA2 promoter by b...

  20. p53 inactivation by point mutations and splice site mutations in human and mouse tumors

    OpenAIRE

    Magnússon, Kristinn P.

    1998-01-01

    The p53 tumor suppressor gene is frequently mutated in human tumors. p53 induces cell cycle arrest and/or apoptosis in response to cellular stress, such as DNA damage, hypoxia and certain activated oncogenes like c-myc. The status of p53 in Burkitt's Iymphoma (BL) cell lines was investigated. The majority of BL lines expressed mutated p53 protein. Functional reconstitution with exogenous wild type (wt) p53 induced apoptosis in a BL line that carried a mutated p53 gene. T...

  1. Regulation of Plasminogen Activator Inhibitor-1 Expression by Tumor Suppressor Protein p53*

    OpenAIRE

    Shetty, Sreerama; Shetty, Praveenkumar; Idell, Steven; Velusamy, Thirunavukkarasu; Bhandary, Yashodhar P.; Shetty, Rashmi S.

    2008-01-01

    H1299 lung carcinoma cells lacking p53 (p53-/-) express minimal amounts of plasminogen activator inhibitor-1 (PAI-1) protein as well as mRNA. p53-/- cells express highly unstable PAI-1 mRNA. Transfection of p53 in p53-/- cells enhanced PAI-1 expression and stabilized PAI-1 mRNA. On the contrary, inhibition of p53 expression by RNA silencing in non-malignant human lung epithelial (Beas2B) cells decreased basal as well as urokinase-type plasminogen activator-induced PAI-...

  2. MdmX Protects p53 from Mdm2-Mediated Degradation

    OpenAIRE

    Jackson, Mark W.; Berberich, Steven J.

    2000-01-01

    The p53 tumor suppressor protein is stabilized in response to cellular stress, resulting in activation of genes responsible for either cell cycle arrest or apoptosis. The cellular pathway for releasing normal cells from p53-dependent cell cycle arrest involves the Mdm2 protein. Recently, a p53-binding protein with homology to Mdm2 was identified and called MdmX. Like Mdm2, MdmX is able to bind p53 and inhibit p53 transactivation; however, the ability of MdmX to degrade p53 has yet to be exami...

  3. Co-mutation of p53, K-ras genes and accumulation of p53 protein and its correlation to clinicopathological features in rectal cancer

    Institute of Scientific and Technical Information of China (English)

    Zhi-Zhong Pan; De-Sen Wan; Gong Chen; Li-Ren Li; Zhen-Hai Lu; Bi-Jun Huang

    2004-01-01

    AIM: To determine the accuracy of p53 gene mutations predicted by overexpression of p53 protein immunohistochemically,and to investigate the co-mutation of p53 and K-rasgenes in rectal cancer and its effect on promoting malignant biologic behaviors of tumors.METHODS: Ninety-seven specimens of rectal cancer were surgically resected in our hospital from August 1996 to October 1997. The hot mutation areas of p53 gene (in exons 5-8) and K-ras gene (in codon 5/12 and 13) were detected with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), and overexpression of p53 protein was detected with immunohistochemistry (IHC) in the 97 specimens of rectal cancer. Correlation between gene mutations and tumor clinicopathologic factors was studied, and survival analysis was penfomed as well.RESULTS: There were 36 cases of p53 gene mutations in 61 p53 protein positive cases, and 21 cases of p53 gene non-mutation in 36 p53 protein negative cases respectively.The coincidence rate of p53 gene mutation by IHC method with PCR-SSCP method was 58.8% (57/97). The mutation rate of p53 gene was 52.6% (51/97), while K-ras gene mutation was observed in codons 12 and 13 in 61 cases with a mutation rate of 62.9% (61/97). Single gene mutation of p53 or K-raswas found in 32 cases. Both p53 and K-ras gene mutation were found in 48 cases. Statistical analysis showed that p53 and K-rasgene mutations were not related to the clinicopathologic factors, including tumor size, gross tumor type, histological classification, differentiation, invasion to intestinal veins, lymphatics and nerves, invasive depth to wall, lymph node metastasis, and Dukes' stages (P>0.05).The survival in patients with no gene mutation, single gene mutation and both gene mutations were similar (P>0.05).CONCLUSION: IHC has a certain false positive and false negative rate in detecting p53 gene mutations. Malignant biological behaviours of rectal cancer are not enhanced by p53 and K-rasgene mutations. Co

  4. Both p53-PUMA/NOXA-Bax-mitochondrion and p53-p21cip1 pathways are involved in the CDglyTK-mediated tumor cell suppression

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhendong, E-mail: zdyu@hotmail.com [Department of Clinical laboratory, Peking University Shenzhen Hospital, Guangdong (China); Wang, Hao [Department of pathology, The Chinese University of Hong Kong, Hong Kong (China); Zhang, Libin; Tang, Aifa; Zhai, Qinna; Wen, Jianxiang; Yao, Li [Department of Clinical laboratory, Peking University Shenzhen Hospital, Guangdong (China); Li, Pengfei, E-mail: lipengfei@cuhk.edu.hk [Department of pathology, The Chinese University of Hong Kong, Hong Kong (China)

    2009-09-04

    CDglyTK fusion suicide gene has been well characterized to effectively kill tumor cells. However, the exact mechanism and downstream target genes are not fully understood. In our study, we found that CDglyTK/prodrug treatment works more efficiently in p53 wild-type (HONE1) cells than in p53 mutant (CNE1) cells. We then used adenovirus-mediated gene delivery system to either knockdown or overexpress p53 and its target genes in these cells. Consistent results showed that both p53-PUMA/NOXA/Bcl2-Bax and p53-p21 pathways contribute to the CDglyTK induced tumor cell suppression. Our work for the first time addressed the role of p53 related genes in the CDglyTK/prodrug system.

  5. Research progress on the structure and function of the P53 gene%P53基因与肿瘤的研究进展

    Institute of Scientific and Technical Information of China (English)

    田云鹏

    2013-01-01

    编码P53蛋白的P53基因是最重要的肿瘤抑制基因之一.人类的大多数肿瘤都存在着P53途径的失活.变异的P53不仅不具备肿瘤抑制子的功能,还可能发挥促进肿瘤发生、发展的作用.P53的基本功能是对细胞应激的应答.因此,我们就P53基因的结构和功能做一综述.

  6. Both p53-PUMA/NOXA-Bax-mitochondrion and p53-p21cip1 pathways are involved in the CDglyTK-mediated tumor cell suppression

    International Nuclear Information System (INIS)

    CDglyTK fusion suicide gene has been well characterized to effectively kill tumor cells. However, the exact mechanism and downstream target genes are not fully understood. In our study, we found that CDglyTK/prodrug treatment works more efficiently in p53 wild-type (HONE1) cells than in p53 mutant (CNE1) cells. We then used adenovirus-mediated gene delivery system to either knockdown or overexpress p53 and its target genes in these cells. Consistent results showed that both p53-PUMA/NOXA/Bcl2-Bax and p53-p21 pathways contribute to the CDglyTK induced tumor cell suppression. Our work for the first time addressed the role of p53 related genes in the CDglyTK/prodrug system.

  7. STAT5A is regulated by DNA damage via the tumor suppressor p53.

    Science.gov (United States)

    Mukhopadhyay, Utpal K; Cass, Jamaica; Raptis, Leda; Craig, Andrew W; Bourdeau, Véronique; Varma, Sonal; SenGupta, Sandip; Elliott, Bruce E; Ferbeyre, Gerardo

    2016-06-01

    Here we report that the STAT5A transcription factor is a direct p53 transcriptional target gene. STAT5A is well expressed in p53 wild type cells but not in p53-null cells. Inhibition of p53 reduces STAT5A expression. DNA damaging agents such as doxorubicin also induced STAT5A expression in a p53 dependent manner. Two p53 binding sites were mapped in the STAT5A gene and named PBS1 and PBS2; these sites were sufficient to confer p53 responsiveness in a luciferase reporter gene. Chromatin immunoprecipitation experiments revealed that PBS2 has constitutive p53 bound to it, while p53 binding to PBS1 required DNA damage. In normal human breast lobules, weak p53 staining correlated with regions of intense STAT5A staining. Interestingly, in a cohort of triple negative breast tumor tissues there was little correlation between regions of p53 and STAT5A staining, likely reflecting a high frequency of p53 mutations that stabilize the protein in these tumors. We thus reveal an unexpected connection between cytokine signaling and p53. PMID:26876578

  8. Knockdown of p53 suppresses Nanog expression in embryonic stem cells

    International Nuclear Information System (INIS)

    Highlights: •We investigate the role of p53 in ESCs in the absence of DNA damage. •p53 knockdown suppresses ESC proliferation. •p53 knockdown downregulates Nanog expression. •p53 is essential for mouse ESC self-renewal. -- Abstract: Mouse embryonic stem cells (ESCs) express high levels of cytoplasmic p53. Exposure of mouse ESCs to DNA damage leads to activation of p53, inducing Nanog suppression. In contrast to earlier studies, we recently reported that chemical inhibition of p53 suppresses ESC proliferation. Here, we confirm that p53 signaling is involved in the maintenance of mouse ESC self-renewal. RNA interference-mediated knockdown of p53 induced downregulation of p21 and defects in ESC proliferation. Furthermore, p53 knockdown resulted in a significant downregulation in Nanog expression at 24 and 48 h post-transfection. p53 knockdown also caused a reduction in Oct4 expression at 48 h post-transfection. Conversely, exposure of ESCs to DNA damage caused a higher reduction of Nanog expression in control siRNA-treated cells than in p53 siRNA-treated cells. These data show that in the absence of DNA damage, p53 is required for the maintenance of mouse ESC self-renewal by regulating Nanog expression

  9. Knockdown of p53 suppresses Nanog expression in embryonic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdelalim, Essam Mohamed, E-mail: emohamed@qf.org.qa [Qatar Biomedical Research Institute, Qatar Foundation, Doha 5825 (Qatar); Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Department of Cytology and Histology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia (Egypt); Tooyama, Ikuo [Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan)

    2014-01-10

    Highlights: •We investigate the role of p53 in ESCs in the absence of DNA damage. •p53 knockdown suppresses ESC proliferation. •p53 knockdown downregulates Nanog expression. •p53 is essential for mouse ESC self-renewal. -- Abstract: Mouse embryonic stem cells (ESCs) express high levels of cytoplasmic p53. Exposure of mouse ESCs to DNA damage leads to activation of p53, inducing Nanog suppression. In contrast to earlier studies, we recently reported that chemical inhibition of p53 suppresses ESC proliferation. Here, we confirm that p53 signaling is involved in the maintenance of mouse ESC self-renewal. RNA interference-mediated knockdown of p53 induced downregulation of p21 and defects in ESC proliferation. Furthermore, p53 knockdown resulted in a significant downregulation in Nanog expression at 24 and 48 h post-transfection. p53 knockdown also caused a reduction in Oct4 expression at 48 h post-transfection. Conversely, exposure of ESCs to DNA damage caused a higher reduction of Nanog expression in control siRNA-treated cells than in p53 siRNA-treated cells. These data show that in the absence of DNA damage, p53 is required for the maintenance of mouse ESC self-renewal by regulating Nanog expression.

  10. Cellular metabolic responses of PET radiotracers to {sup 188}Re radiation in an MCF7 cell line containing dominant-negative mutant p53

    Energy Technology Data Exchange (ETDEWEB)

    Cheon, Gi Jeong [Laboratory of Nuclear Medicine Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of) and Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)]. E-mail: larry@kcch.re.kr; Chung, Hye-Kyung [Laboratory of Nuclear Medicine Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Choi, Jung-A [Laboratory of Radiation Experimental Therapeutics, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Lee, Su-Jae [Laboratory of Radiation Experimental Therapeutics, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Ahn, Soon-Hyuk [Laboratory of Nuclear Medicine Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Lee, Tae-Sup [Laboratory of Nuclear Medicine Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Choi, Chang Woon [Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Lim, Sang Moo [Department of Nuclear Medicine, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)

    2007-05-15

    with an altered function of p53.

  11. Modulation of p53 activity by IκBα: Evidence suggesting a common phylogeny between NF-κB and p53 transcription factors

    Directory of Open Access Journals (Sweden)

    Gelfand Erwin W

    2005-06-01

    Full Text Available Abstract Background In this work we present evidence that the p53 tumor suppressor protein and NF-κB transcription factors could be related through common descent from a family of ancestral transcription factors regulating cellular proliferation and apoptosis. P53 is a homotetrameric transcription factor known to interact with the ankyrin protein 53BP2 (a fragment of the ASPP2 protein. NF-κB is also regulated by ankyrin proteins, the prototype of which is the IκB family. The DNA binding sequences of the two transcription factors are similar, sharing 8 out of 10 nucleotides. Interactions between the two proteins, both direct and indirect, have been noted previously and the two proteins play central roles in the control of proliferation and apoptosis. Results Using previously published structure data, we noted a significant degree of structural alignment between p53 and NF-κB p65. We also determined that IκBα and p53 bind in vitro through a specific interaction in part involving the DNA binding region of p53, or a region proximal to it, and the amino terminus of IκBα independently or cooperatively with the ankyrin 3 domain of IκBα In cotransfection experiments, κBα could significantly inhibit the transcriptional activity of p53. Inhibition of p53-mediated transcription was increased by deletion of the ankyrin 2, 4, or 5 domains of IκBα Co-precipitation experiments using the stably transfected ankyrin 5 deletion mutant of κBα and endogenous wild-type p53 further support the hypothesis that p53 and IκBα can physically interact in vivo. Conclusion The aggregate results obtained using bacterially produced IκBα and p53 as well as reticulocyte lysate produced proteins suggest a correlation between in vitro co-precipitation in at least one of the systems and in vivo p53 inhibitory activity. These observations argue for a mechanism involving direct binding of IκBα to p53 in the inhibition of p53 transcriptional activity, analogous to

  12. Gain of Cellular Adaptation Due to Prolonged p53 Impairment Leads to Functional Switchover from p53 to p73 during DNA Damage in Acute Myeloid Leukemia Cells*

    OpenAIRE

    Chakraborty, Juni; Banerjee, Shuvomoy; Ray, Pallab; Hossain, Dewan Md Sakib; Bhattacharyya, Sankar; Adhikary, Arghya; Chattopadhyay, Sreya; Das, Tanya; Sa, Gaurisankar

    2010-01-01

    Tumor suppressor p53 plays the central role in regulating apoptosis in response to genotoxic stress. From an evolutionary perspective, the activity of p53 has to be backed up by other protein(s) in case of any functional impairment of this protein, to trigger DNA damage-induced apoptosis in cancer cells. We adopted multiple experimental approaches to demonstrate that in p53-impaired cancer cells, DNA damage caused accumulation of p53 paralogue p73 via Chk-1 that strongly impacted Bax expressi...

  13. p53 polymorphisms associated with mutations in and loss of heterozygosity of the p53 gene in male oral squamous cell carcinomas in Taiwan

    OpenAIRE

    Hsieh, L-L; Huang, T-H; Chen, I-H; Liao, C-T; Wang, H-M; Lai, C-H; Liou, S-H; Chang, J T-C; Cheng, A-J

    2004-01-01

    The present study was designed to examine whether different p53 haplotypes of exon 4–intron 3–intron 6 affect the frequency of mutations and loss of heterozygosity (LOH) of the p53 gene in male oral squamous cell carcinomas (OSCCs) in Taiwan. We found that individuals without two Pro-W-G alleles had significantly higher frequency of p53 mutations than those with two Pro-W-G alleles (odds ratio (OR)=1.98; 95% confidence interval (CI), 1.10–3.56). Out of the 172 p53 gene exon 4 informative male...

  14. Mutant p53 accumulates in cycling and proliferating cells in the normal tissues of p53 R172H mutant mice

    OpenAIRE

    Goh, Amanda M.; Xue, Yuezhen; Leushacke, Marc; LI, LING; Wong, Julin S.; Chiam, Poh Cheang; Rahmat, Siti Aishah Binte; Mann, Michael B.; Mann, Karen M.; Barker, Nick; Lozano, Guillermina; Terzian, Tamara; Lane, David P

    2015-01-01

    The tumour suppressor p53 is regulated primarily at the protein level. In normal tissues its levels are maintained at a very low level by the action of specific E3 ligases and the ubiquitin proteosome pathway. The mutant p53 protein contributes to transformation, metastasis and drug resistance. High levels of mutant p53 can be found in tumours and the accumulation of mutant p53 has previously been reported in pathologically normal cells in human skin. We show for the first time that similarly...

  15. Studies on The Interactions Between NIRF and P53%NIRF对P53蛋白泛素化作用的研究

    Institute of Scientific and Technical Information of China (English)

    段昌柱; 蒲淑萍; TSUTOMU; MORI; HIDEO; KOCHI; 邱宗荫

    2006-01-01

    HEK293和HeLa细胞分别被Np95/ICBP90-like RING finger protein(NIRF)和P53转染后,细胞上清和免疫沉淀产物用SDS-聚丙烯酰胺凝胶电泳免疫印迹法分析;细菌合成GST-P53后,用GST pull-down技术检测NIRF与P53相互作用;在GST-P53、E1、E2和NIRF体外泛素化反应系统中,检测NIRF对P53的体外泛素化.结果表明:NIRF能与P53相互作用,NIRF不仅能与P53特异性结合,而且还会将P53泛素化,这种相互作用在细胞内和细胞外均能发生.推测NIRF可能是P53的一个新的负调节蛋白.

  16. ISG20L1 is a p53 family target gene that modulates genotoxic stress-induced autophagy

    Directory of Open Access Journals (Sweden)

    Johnson Kimberly N

    2010-04-01

    Full Text Available Abstract Background Autophagy is characterized by the sequestration of cytoplasm and organelles into multimembrane vesicles and subsequent degradation by the cell's lysosomal system. It is linked to many physiological functions in human cells including stress response, protein degradation, organelle turnover, caspase-independent cell death and tumor suppression. Malignant transformation is frequently associated with deregulation of autophagy and several tumor suppressors can modulate autophagic processes. The tumor suppressor p53 can induce autophagy after metabolic or genotoxic stress through transcriptionally-dependent and -independent mechanisms. In this study we expand on the former mechanism by functionally characterizing a p53 family target gene, ISG20L1 under conditions of genotoxic stress. Results We identified a p53 target gene, ISG20L1, and show that transcription of the gene can be regulated by all three p53 family members (p53, p63, and p73. We generated an antibody to ISG20L1 and found that it localizes to the nucleolar and perinucleolar regions of the nucleus and its protein levels increase in a p53- and p73-dependent manner after various forms of genotoxic stress. When ectopically expressed in epithelial cancer-derived cell lines, ISG20L1 expression decreased clonogenic survival without a concomitant elevation in apoptosis and this effect was partially rescued in cells that were ATG5 deficient. Knockdown of ISG20L1 did not alter 5-FU induced apoptosis as assessed by PARP and caspase-3 cleavage, sub-G1 content, and DNA laddering. Thus, we investigated the role of ISG20L1 in autophagy, a process commonly associated with type II cell death, and found that ISG20L1 knockdown decreased levels of autophagic vacuoles and LC3-II after genotoxic stress as assessed by electron microscopy, biochemical, and immunohistochemical measurements of LC3-II. Conclusions Our identification of ISG20L1 as a p53 family target and discovery that modulation

  17. Radiosensitivity in lung cancer with focus on p53

    CERN Document Server

    Bergqvist, M

    2002-01-01

    In Sweden approximately 2800 new lung cancer patients are diagnosed every year. Radiotherapy is used with curative intention in certain groups of patients. The aim of this thesis is to study the basis of differences in radioresistance and the possibility to predict response to radiotherapy. In the first study we investigated, using the comet assay, four lung cancer cell lines with different sensitivity towards radiation. A clear dose-response relationship for radiation-induced DNA single strand and double strand breaks were found. All cell lines showed a remarkably efficient repair of both the DNA single strand and double strand breaks one hour after irradiation. However, further studies in one radioresistant and one radiosensitive cell line demonstrated that repair during the first 15 min had the best accordance with radiosensitivity measured as surviving fraction. In the second and third study, sequencing studies of the p53 gene were performed on cell lines as well as on tumour material. Cell lines that wer...

  18. Regulation of p53 in NIH3T3 mouse fibroblasts following hyperosmotic stress

    DEFF Research Database (Denmark)

    Lambert, Ian Henry; Enghoff, Maria Stine; Brandi, Marie-Luise;

    2015-01-01

    The aim of this project was to analyze the regulation of p53 expression in NIH3T3 fibroblasts under the influence of increasing hyperosmotic stress. Expression of p53 showed a biphasic response pattern in NIH3T3 cells under increasing osmotic stress (337 mOsm to 737 mOsm) with a maximum at 587 m......Osm. Under isotonic conditions p53 expression increased after addition of the proteasome inhibitor MG132 indicating that cellular p53 levels in unperturbed cells is kept low by proteasomal degradation. However, under hypertonic conditions p53 synthesis as well as p53 degradation were significantly reduced...... and it is demonstrated that the increase in p53 expression observed when tonicity is increased from 337 to 587 mOsm reflects that degradation is more inhibited than synthesis, whereas the decrease in p53 expression at higher tonicities reflects that synthesis is more inhibited than degradation. The...

  19. Nerve growth factor receptor negates the tumor suppressor p53 as a feedback regulator

    Science.gov (United States)

    Zhou, Xiang; Hao, Qian; Liao, Peng; Luo, Shiwen; Zhang, Minhong; Hu, Guohui; Liu, Hongbing; Zhang, Yiwei; Cao, Bo; Baddoo, Melody; Flemington, Erik K; Zeng, Shelya X; Lu, Hua

    2016-01-01

    Cancer develops and progresses often by inactivating p53. Here, we unveil nerve growth factor receptor (NGFR, p75NTR or CD271) as a novel p53 inactivator. p53 activates NGFR transcription, whereas NGFR inactivates p53 by promoting its MDM2-mediated ubiquitin-dependent proteolysis and by directly binding to its central DNA binding domain and preventing its DNA-binding activity. Inversely, NGFR ablation activates p53, consequently inducing apoptosis, attenuating survival, and reducing clonogenic capability of cancer cells, as well as sensitizing human cancer cells to chemotherapeutic agents that induce p53 and suppressing mouse xenograft tumor growth. NGFR is highly expressed in human glioblastomas, and its gene is often amplified in breast cancers with wild type p53. Altogether, our results demonstrate that cancers hijack NGFR as an oncogenic inhibitor of p53. DOI: http://dx.doi.org/10.7554/eLife.15099.001 PMID:27282385

  20. Reactivating mutant p53 using small molecules as zinc metallochaperones: awakening a sleeping giant in cancer

    Science.gov (United States)

    Blanden, Adam R.; Yu, Xin; Loh, Stewart N.; Levine, Arnold J.; Carpizo, Darren R.

    2016-01-01

    Tumor protein p53 (TP53) is the most commonly mutated gene in human cancer. The majority of mutations are missense, and generate a defective protein that is druggable. Yet, for decades, the small-molecule restoration of wild-type (WT) p53 function in mutant p53 tumors (so-called p53 mutant ‘reactivation’) has been elusive to researchers. The p53 protein requires the binding of a single zinc ion for proper folding, and impairing zinc binding is a major mechanism for loss of function in missense mutant p53. Here, we describe recent work defining a new class of drugs termed zinc metallochaperones that restore WT p53 structure and function by restoring Zn2+ to Zn2+-deficient mutant p53. PMID:26205328

  1. Mitochondrial localization of the low level p53 protein in proliferative cells

    International Nuclear Information System (INIS)

    p53 protein plays a central role in suppressing tumorigenesis by inducing cell cycle arrest or apoptosis through transcription-dependent and -independent mechanisms. Emerging publications suggest that following stress, a fraction of p53 translocates to mitochondria to induce cytochrome c release and apoptosis. However, the localization of p53 under unstressed conditions remains largely unexplored. Here we show that p53 is localized at mitochondria in absence of apoptotic stimuli, when cells are proliferating, localization observed in various cell types (rodent and human). This is also supported by acellular assays in which p53 bind strongly to mitochondria isolated from rat liver. Furthermore, the mitochondria subfractionation study and the alkaline treatment of the mitochondrial p53 revealed that the majority of mitochondrial p53 is present in the membranous compartments. Finally, we identified VDAC, a protein of the mitochondrial outer-membrane, as a putative partner of p53 in unstressed/proliferative cells.

  2. The role of p53 in radiation therapy outcomes for favorable-to-intermediate-risk prostate cancer

    International Nuclear Information System (INIS)

    Purpose: Some prostate cancers may have molecular alterations that render them less responsive to radiation therapy; identification of these alterations before treatment might allow improved treatment optimization. This study investigated whether p53, a potential molecular determinant, could predict long-term radiation therapy outcome in a restricted group of relatively favorable-risk prostate cancer patients treated uniformly with irradiation alone. Methods and Materials: This study included 53 patients previously treated with radiotherapy for favorable-to-intermediate-risk prostate cancer. These patients were selected for relatively low pretreatment PSAs (≤21 ng/mL) and Gleason scores (≤7) to decrease the likelihood of nonlocalized disease, because disease localization was necessary to examine the efficacy of localized radiation therapy. The status of p53 was immunohistochemically assessed in paraffin-embedded pretreatment biopsy specimens, along with appropriate controls. This marker was selected based upon a usable mutation prevalence in early-stage prostate cancer and its potential linkage with radiation response via cell cycle, DNA repair, and cell death pathways. Correlation between p53 mutation and clinical outcome was analyzed in univariate and multivariate fashion and included conventional prognosticators, such as stage, grade, and PSA. Freedom from biochemical failure was determined using American Society for Therapeutic Radiology and Oncology criteria. Limitations of prior studies were potentially avoided by requiring adequate posttreatment follow-up (median follow-up in nonfailing patients of 5.1 years), as well as pretreatment PSA and Gleason scores that suggested localized disease, and uniformity of treatment. Results: The total group of 53 favorable-to-intermediate-risk patients demonstrated an actuarial biochemical failure rate of 35% at 5 years. Forty percent of all specimens had a greater than 10% labeling index for p53 mutation, and

  3. Relation between p53 (exon 7) mutation and p53 overexpression in human cervical cancers%宫颈癌p53外显子7突变与p53蛋白高表达的关系

    Institute of Scientific and Technical Information of China (English)

    张娜; 李惠芳; 常艳丽; 梁莎

    2001-01-01

    目的探讨宫颈癌p53外显子7突变与p53蛋白高表达的关系。方法采用免疫组织化学、聚合酶链反应(PCR)、限制性酶解片段长度多态性(RFLP)分析等方法对49例宫颈癌组织石蜡包埋标本中p53外显子7的突变与p53蛋白表达进行了检测。结果 p53外显子7的突变率8.2%(4/49)显著低于p53蛋白阳性率49.0%(24/49)(χ2=18.05,P<0.001);p53外显子7突变不一定p53蛋白阳性。结论 p53外显子7突变可能是部分宫颈癌变的一个重要因素;大部分宫颈癌可能主要由于高危人乳头状瘤病毒(HPV)感染后,通过E6/p53蛋白复合物的形成使p53蛋白失活所致。%Objective To investigate the relation between p53 (exon 7) mutations and p53 overexpression in human cervical cancer.Methods p53 (exon 7) mutation and p53 overexpression were examined by immunohistochemistry,polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis in 49 cases of cervical cancers on their paraffin-embedded tissue specimens.Results There was significant difference between p53 (exon 7) mutation 4/49 (8.2%) and p53 overexpression 24/49 (49.0%) in cervical cancer (χ2=18.05,P<0.001);not all cases of p53 mutation had p53 protein positive.Conclusion The p53 (exon 7) mutation is an important factor in part of cervical cancers,but anomalous structure and inactivation of p53 proteins caused by E6/p53 protein complex formed in high risk HPV infection are the significant cause of the greater part of cervical cancers.

  4. The role and prognostic significance of p53 mutation in colorectal carcinomas

    Institute of Scientific and Technical Information of China (English)

    Chen Yang Ji; DR Smith; HS Goh

    2000-01-01

    AIM To study the prognostic significance of the p53 cDNA mutation and mutant p53 protein in colorectaladenocarcinomas.METHODS p53 cDNA mutaiton was detected with RT-PCR-SSCP, and mutant p53 protein overexpressionwas detected by PAb 240 monoclonal antibody in 100 cases of colorectal adenocarcinomas. The follow-upsurvey of all patients were done within the five years after operation, and comparing with p53 cDNAmutation and mutant p53 protein overexpression for the prognostic significance of colorectaladenocarcinomas. The data is treated with SPSS computer program, Kaplan-Meier Survival Plots werecalculated and analyzed by Log-rank analysis.RESULTS Fifty-one cases of p53 eDNA mutations (51%) were found with RT-PCR-SSCP and 76 cases ofmutant p53 protein overexpression (76%) found with PAb 240 monoclonal antibody immunohistochemistrystaining in 100 cases of colorectal adenocarcinomas. There are no relationship with Dukes stage in thestatistics in p53 eDNA mutation (mutation: Dukes A 9%, B 10%, C 20%, D 12%; No mutation: A 13%, B12%, C 12%, D 12%) and mutant p53 protein overexpression (positive: Dukes A 17%, B 6%, C 27%, D16%; negative: A 5%, B 6%, C 5%, D 8%) (P<0.05). Moreover, the data show p53 cDNA mutation isassociated with mutant p53 protein overexpression (both positive 49%, single positive 29%, both negative22%) (P<0.01), p53 eDNA mutation can provide prognostic information (p53 eDNA mutation positive:alive 35, dead 16; negative: alive 42, dead 7) (P<0.05), and mutant p53 protein overexpression isambiguous and does not assess prognosis (p53 protein overexpression positive: alive 58, dead 18; negative:alive 19, dead 5) (P = 0.72) with Kaplan-Meier Survival Plots and Log-rank analysis.CONCLUSION p53 eDNA mutation is associated with mutant p53 protein overexpression (p53 eDNAmutation and mutant p53 protein overexpression both positive 49%, single positive 29%, both negative 22%)(P<0.01) and p53 eDNA mutation can provide poor prognostic information, and is the

  5. Human papillomavirus 18 E6 inhibits phosphorylation of p53 expressed in HeLa cells

    Directory of Open Access Journals (Sweden)

    Ajay Amrendra K

    2012-01-01

    Full Text Available Abstract Background In HPV infected cells p53 function is abrogated by E6 and even ectopically expressed p53 is unable to perform tumor suppressor functions. In addition to facilitating its degradation, E6 may also inhibit p53 transactivity, though the mechanisms are still poorly understood. It has been reported that inhibition of p300, an acetyltransferase responsible for p53 acetylation is inactivated by E6. Activation of overexpressed p53 to cause cell growth inhibition is facilitated by its phosphorylation. Previously, we reported that non-genotoxically overexpressed p53 in HeLa cells needs to be phosphorylated to perform its cell growth inhibitory functions. Since over expressed p53 by itself was not activated, we hypothesized an inhibitory role for E6. Results Majority of reports proposes E6 mediated degradation of p53 as a possible reason for its inactivation. However, results presented here for the first time demonstrate that overexpressed p53 is not directly associated with E6 and therefore free, yet it is not functionally active in HPV positive cells. Also, the stability of overexpressed p53 does not seem to be an issue because inhibition of proteasomal degradation did not increase the half-life of overexpressed p53, which is more than endogenous p53. However, inhibition of proteasomal degradation prevents the degradation of endogenous p53. These findings suggest that overexpressed p53 and endogenous p53 are differentially subjected to proteasomal degradation and the reasons for this discrepancy remain unclear. Our studies demonstrate that p53 over expression has no effect on anchorage independent cell-growth and E6 nullifies its cell growth inhibitory effect. E6 overexpression abrogates OA induced p53 occupancy on the p21 promoter and cell death as well. E6 did not decrease p53 protein but phospho-p53 level was significantly reduced. Conclusion We report for the first time that E6 de-activates p53 by inhibiting its phosphorylation

  6. Def defines a conserved nucleolar pathway that leads p53 to proteasome-independent degradation

    OpenAIRE

    Tao, Ting; Hui SHI; Guan, Yihong; Huang, Delai; Chen, Ye; Lane, David P; Chen, Jun; Peng, Jinrong

    2013-01-01

    p53 protein turnover through the ubiquitination pathway is a vital mechanism in the regulation of its transcriptional activity; however, little is known about p53 turnover through proteasome-independent pathway(s). The digestive organ expansion factor (Def) protein is essential for the development of digestive organs. In zebrafish, loss of function of def selectively upregulates the expression of p53 response genes, which raises a question as to what is the relationship between Def and p53. W...

  7. Clinical Significance of Mutant P53 Protein Expression in Lung Adenocarcinoma

    OpenAIRE

    Chun’an BIAN; Li, Zhongyou; Youtao XU; Wang, Jie; Xu, Lin; Shen, Hongbing

    2015-01-01

    Background and objective P53 is a tumor protein that acts as a tumor suppressor. The mutation of P53 may cause loss of tumor suppressor functions and gain of functions favoring cellular proliferation and apoptosis inhibition. The clinical implications of the tumor protein P53 gene (TP53) mutation in lung adenocarcinoma are indefinite. The aim of this study is to explore the clinical significance of the mutant P53 protein expression in lung adenocarcinoma tissues. Methods The clinicopathologic...

  8. New tricks of an old molecule: lifespan regulation by p53

    OpenAIRE

    Bauer, Johannes H.; HELFAND, STEPHEN L.

    2006-01-01

    As guardian of the genome the tumor suppressor p53 controls a crucial point in protection from cellular damage and response to stressors. Activation of p53 can have beneficial (DNA repair) or detrimental (apoptosis) consequences for individual cells. In either case activation of p53 is thought to safeguard the organism at large from the deleterious effects of various stresses. Recent data suggest that the function of p53 might also play a role in the regulation of organismal lifespan. Increas...

  9. p53 Mutations and Protein Overexpression in Primary Colorectal Cancer and its Liver Metastasis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To compare p53 status in primary and hepatic metastatic colorectal cancer in 34 patients. Methods: p53 gene status (exons 5- 9) was e