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

    2007-01-01

    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

    The two gene products of the CDKN2A gene, p16 and p19ARF, have recently been linked to each of two major tumour suppressor pathways in human carcinogenesis, the RB1 pathway and the p53 pathway. p16 inhibits the phosphorylation of the retinoblastoma gene product by cyclin D-dependent kinases...... of aberrations of CDKN2A, MDM2 and p53, since this has not been analysed previously. We investigated 37 DLCL for aberrations of p15, p16, p19ARF, MDM2, and p53 at the epigenetic, genetic and/or protein levels. Homozygous deletion of CDKN2A was detected in seven (19%) of 37 tumours, and another three cases were...... 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. p53 protein alterations in adult astrocytic tumors and oligodendrogliomas

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    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

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

    Science.gov (United States)

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

    1995-12-01

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

  5. FREQUENT STRUCTURE ALTERATIONS OF p53 GENE IN NASOPHARYNGEAL CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    龙江斌; 区宝祥; 梁启万; 李辉梅

    1998-01-01

    By southern hybridization with 1.8 kb cDNA probe,a high freqnency (40.5%) of structural abnormality of p 53 gene was observed in primary nasopharyngeal carcinoma (NPC) biopsies. The regioas of exons 1 to 4 of the gene were examined by poiymerase chain reaction-single strand conformation polymorphism, no point nmtation was found. Because very low rate of point mutation had been reported in exons 5 to 8,we considered that structural ahnormality in the region of exons 1 to 8 of the gene might be uncommon in NPC. The speetrophotometer scaaning analysis of outoradiograms and rehybridization investigation of nitrocellulose filter with exon 11 probe indicated that most of structure aberrations we observed might be rearrangement occurring in exon ll.

  6. 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.

  7. Tumor suppressor WWOX and p53 alterations and drug resistance in glioblastomas

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    Ming-Fu eChiang

    2013-03-01

    Full Text Available Tumor suppressor p53 are frequently mutated in glioblastomas (GBMs and appears to contribute, in part, to resistance to temozolomide and therapeutic drugs. WW domain-containing oxidoreductase WWOX (FOR or WOX1 is a proapoptotic protein and is considered as a tumor suppressor. Loss of WWOX gene expression is frequently seen in malignant cancer cells due to promoter hypermethylation, genetic alterations, and translational blockade. Intriguingly, ectopic expression of wild type WWOX preferentially induces apoptosis in human glioblastoma cells harboring mutant p53. WWOX is known to physically bind and stabilize wild type p53. Here, we provide an overview for the updated knowledge in p53 and WWOX, and postulate a potential scenarios that wild type and mutant p53, or isoforms, modulate the apoptotic function of WWOX. We propose that triggering WWOX activation by therapeutic drugs under p53 functional deficiency is needed to overcome TMZ resistance and induce GBM cell death.

  8. Conformational altered p53 as an early marker of oxidative stress in Alzheimer's disease.

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    Buizza, Laura; Cenini, Giovanna; Lanni, Cristina; Ferrari-Toninelli, Giulia; Prandelli, Chiara; Govoni, Stefano; Buoso, Erica; Racchi, Marco; Barcikowska, Maria; Styczynska, Maria; Szybinska, Aleksandra; Butterfield, David Allan; Memo, Maurizio; Uberti, Daniela

    2012-01-01

    In order to study oxidative stress in peripheral cells of Alzheimer's disease (AD) patients, immortalized lymphocytes derived from two peculiar cohorts of patients, referring to early onset AD (EOSAD) and subjects harboured AD related mutation (ADmut), were used. Oxidative stress was evaluated measuring i) the typical oxidative markers, such as HNE Michel adducts, 3 Nitro-Tyrosine residues and protein carbonyl on protein extracts, ii) and the antioxidant capacity, following the enzymatic kinetic of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRD). We found that the signs of oxidative stress, measured as oxidative marker levels, were evident only in ADmut but not in EOSAD patients. However, oxidative imbalance in EOSAD as well as ADmut lymphocytes was underlined by a reduced SOD activity and GRD activity in both pathological groups in comparison with cells derived from healthy subjects. Furthermore, a redox modulated p53 protein was found conformational altered in both EOSAD and ADmut B lymphocytes in comparison with control cells. This conformational altered p53 isoform, named "unfolded p53", was recognized by the use of two specific conformational anti-p53 antibodies. Immunoprecipitation experiments, performed with the monoclonal antibodies PAb1620 (that recognizes p53wt) and PAb240 (that is direct towards unfolded p53), and followed by the immunoblotting with anti-4-hydroxynonenal (HNE) and anti- 3-nitrotyrosine (3NT) antibodies, showed a preferential increase of nitrated tyrosine residues in unfolded p53 isoform comparing to p53 wt protein, in both ADmut and EOSAD. In addition, a correlation between unfolded p53 and SOD activity was further found. Thus this study suggests that ROS/RNS contributed to change of p53 tertiary structure and that unfolded p53 can be considered as an early marker of oxidative imbalance in these patients.

  9. Conformational altered p53 as an early marker of oxidative stress in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Laura Buizza

    Full Text Available In order to study oxidative stress in peripheral cells of Alzheimer's disease (AD patients, immortalized lymphocytes derived from two peculiar cohorts of patients, referring to early onset AD (EOSAD and subjects harboured AD related mutation (ADmut, were used. Oxidative stress was evaluated measuring i the typical oxidative markers, such as HNE Michel adducts, 3 Nitro-Tyrosine residues and protein carbonyl on protein extracts, ii and the antioxidant capacity, following the enzymatic kinetic of superoxide dismutase (SOD, glutathione peroxidase (GPx and glutathione reductase (GRD. We found that the signs of oxidative stress, measured as oxidative marker levels, were evident only in ADmut but not in EOSAD patients. However, oxidative imbalance in EOSAD as well as ADmut lymphocytes was underlined by a reduced SOD activity and GRD activity in both pathological groups in comparison with cells derived from healthy subjects. Furthermore, a redox modulated p53 protein was found conformational altered in both EOSAD and ADmut B lymphocytes in comparison with control cells. This conformational altered p53 isoform, named "unfolded p53", was recognized by the use of two specific conformational anti-p53 antibodies. Immunoprecipitation experiments, performed with the monoclonal antibodies PAb1620 (that recognizes p53wt and PAb240 (that is direct towards unfolded p53, and followed by the immunoblotting with anti-4-hydroxynonenal (HNE and anti- 3-nitrotyrosine (3NT antibodies, showed a preferential increase of nitrated tyrosine residues in unfolded p53 isoform comparing to p53 wt protein, in both ADmut and EOSAD. In addition, a correlation between unfolded p53 and SOD activity was further found. Thus this study suggests that ROS/RNS contributed to change of p53 tertiary structure and that unfolded p53 can be considered as an early marker of oxidative imbalance in these patients.

  10. Clinical significance of different types of p53 gene alteration in surgically treated prostate cancer.

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    Kluth, Martina; Harasimowicz, Silvia; Burkhardt, Lia; Grupp, Katharina; Krohn, Antje; Prien, Kristina; Gjoni, Jovisa; Haß, Thomas; Galal, Rami; Graefen, Markus; Haese, Alexander; Simon, Ronald; Hühne-Simon, Julia; Koop, Christina; Korbel, Jan; Weischenfeld, Joachim; Huland, Hartwig; Sauter, Guido; Quaas, Alexander; Wilczak, Waldemar; Tsourlakis, Maria-Christina; Minner, Sarah; Schlomm, Thorsten

    2014-09-15

    Despite a multitude of p53 immunohistochemistry (IHC) studies, data on the combined effect of nuclear p53 protein accumulation and TP53 genomic inactivation are lacking for prostate cancer. A tissue microarray including 11,152 prostate cancer samples was analyzed by p53 IHC and fluorescence in situ hybridization. Nuclear p53 accumulation was found in 10.1% of patients including 1.4% with high-level and 8.7% with low-level immunostaining. TP53 sequencing revealed that 17 of 22 (77%) cases with high-level p53 immunostaining, but only 3% (1 of 31) low-level p53 cases carried putative dominant-negative mutations. TP53 deletions occurred in 14.8% of cancers. Both deletions and protein accumulation were linked to unfavorable tumor phenotype and prostate specific antigen (PSA) recurrence (pp53 positivity (8.7%) had identical risks of PSA recurrence, which were markedly higher than in cancers without p53 alterations (pp53 deletion and low-level p53 positivity (1.5%) had a worse prognosis than patients with only one of these alterations (pp53 immunostaining or homozygous inactivation through deletion of one allele and disrupting translocation involving the second allele had the worst outcome, independent from clinical and pathological parameters. These data demonstrate a differential clinical impact of various TP53 alterations in prostate cancer. Strong p53 immunostaining-most likely accompanying dominant negative or oncogenic p53 mutation-has independent prognostic relevance and may thus represent a clinical useful molecular feature of prostate cancer.

  11. HPV detection and p53 alteration in squamous cell verrucous malignancies of the lower genital tract.

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

    1993-12-01

    We examined five cases of verrucous carcinoma (VC) and two cases of giant condyloma of Buschke-Löwenstein (GCBL) associated with invasive squamous cell carcinoma (ISCC), by immunocytochemistry and molecular techniques. Neither human papillomavirus (HPV) footprints nor p53-altered expression and/or mutation were observed among the cases of VC. By contrast, both cases of GCBL with ISCC turned out to be HPV 6 or 11 positive, showed overexpression of p53 and, one of the two, a mutation in the nucleotide sequence of this tumor suppressor gene. The results point out that VC and GCBL with ISCC, in spite of some morphologic similarities, are two distinct entities, the former being unrelated to both HPV and p53 inactivation and the latter related to both. Regarding p53, immunocytochemical and molecular data on GCBL with ISCC suggest a role of mutant p53 in the progression of malignancy into invasion.

  12. 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.

  13. 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.

  14. 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.

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

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

    2008-03-01

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

  16. 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......-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...... developed MDM2 over-expression. CONCLUSION: Our data are consistent with the notion that p53 alterations are important for the histological transformation of follicle centre lymphoma. However, the data also suggest that relapsing follicle centre lymphomas without overt transformation often have p53...

  17. Translocation t(8;14)(q24;q11) with concurrent PTEN alterations and deletions of STIL/TAL1 and CDKN2A/B in a pediatric case of acute T-lymphoblastic leukemia: A genetic profile associated with adverse prognosis.

    Science.gov (United States)

    Skalska-Sadowska, Jolanta; Dawidowska, Małgorzata; Szarzyńska-Zawadzka, Bronisława; Jarmuż-Szymczak, Małgorzata; Czerwińska-Rybak, Joanna; Machowska, Ludomiła; Derwich, Katarzyna

    2017-04-01

    We report a pediatric case of acute T-lymphoblastic leukemia (T-ALL) with NOTCH1(wt) , FBXW7(wt) , STIL/TAL1, and PTEN (exons 2, 3, 4, 5) monoallelic deletions, biallelic CDKN2A/B deletion, and a minor t(8;14)(q24;q11)-positive subclone. Undetectable by a flow cytometric minimal residual disease assay, the t(8;14)(q24;q11) subclone expanded as detected by fluorescence in situ hybridization from 5% at diagnosis to 26% before consolidation and 100% at relapse bearing a monoallelic deletion (exons 2, 3) with a new frameshift mutation of PTEN and the same set of remaining molecular alterations. This case documents an unfavorable prognostic potential of a co-occurrence of this set of molecular genetic events and addresses risk stratification in T-ALL.

  18. Alterations in K-ras, APC and p53-multiple genetic pathway in colorectal cancer among Indians.

    Science.gov (United States)

    Malhotra, Pooja; Anwar, Mumtaz; Nanda, Neha; Kochhar, Rakesh; Wig, Jai Dev; Vaiphei, Kim; Mahmood, Safrun

    2013-06-01

    The incidence of colorectal cancer (CRC) is increasing rapidly in Asian countries during the past few decades, but no comprehensive analysis has been done to find out the exact cause of this disease. In this study, we investigated the frequencies of mutations and expression pattern of K-ras, APC (adenomatosis polyposis coli) and p53 in tumor, adjoining and distant normal mucosa and to correlate these alterations with patients clinicopathological parameters as well as with the survival. Polymerase chain reaction (PCR)-restriction digestion was used to detect mutations in K-ras and PCR-SSCP (Single Strand Conformation Polymorphism) followed by DNA sequencing was used to detect mutations in APC and p53 genes. Immunohistochemistry was used to detect the expression pattern of K-ras, APC and p53 proteins. The frequencies of mutations of K-ras, APC and p53 in 30 tumor tissues samples were 26.7 %, 46.7 % and 20 %, respectively. Only 3.3 % of tumors contained mutations in all the three genes. The most common combination of mutation was APC and p53 whereas mutation in both p53 and K-ras were extremely rare. There was no association between the mutations and expression pattern of K-ras, APC and p53 (p>0.05). In Indians, the frequency of alterations of K-ras and APC is similar as in Westerns, whereas the frequency of p53 mutation is slightly lower. The lack of multiple mutations in tumor specimens suggests that these genetic alterations might have independent influences on CRC development and there could be multiple alternative genetic pathways to CRC in our present study cohort.

  19. P53 alters the cytotoxicity and genotoxicity for oxidized graphene in human B-lymphoblastoid cells

    Science.gov (United States)

    Petibone, Dayton Matthew

    Widespread use of oxidized graphene nanomaterials in industry, medicine, and consumer products raises concern about potential adverse impacts on human health. The p53 tumor suppressor protein is crucial to maintaining cellular and genetic stability to prevent carcinogenesis. Here, we show that oxygen functionalized graphene (f-G) absorption and p53 functional status correlate with cytotoxicity and genotoxicity in human B-lymphoblastoid cells. Trends in f-G absorption by were dose-dependent. Cells with functional p53 exposed to f-G arrested in G0/G1 phase of the cell cycle, suppressed f-G induced reactive oxygen species (ROS), and had elevated apoptosis. While compared to p53 competent cells, the p53 deficient cells exposed to f-G accumulated in S-phase of the cell cycle, had elevated ROS levels, and evaded apoptosis. The f-G genotoxicity was evident as increased loss-of-heterozygosity mutants independent of p53 status, and structural chromosome damage in p53 deficient cells. These findings have broad implications for the safety and efficacy of oxidized graphene nanomaterials in industrial, consumer products and biomedical applications.

  20. Altered p53 and NOX1 activity cause bioenergetic defects in a SCA7 polyglutamine disease model.

    Science.gov (United States)

    Ajayi, Abiodun; Yu, Xin; Wahlo-Svedin, Carolina; Tsirigotaki, Galateia; Karlström, Victor; Ström, Anna-Lena

    2015-01-01

    Spinocerebellar ataxia type 7 (SCA7) is one of the nine neurodegenerative disorders caused by expanded polyglutamine (polyQ) domains. Common pathogenic mechanisms, including bioenergetics defects, have been suggested for these so called polyQ diseases. However, the exact molecular mechanism(s) behind the metabolic dysfunction is still unclear. In this study we identified a previously unreported mechanism, involving disruption of p53 and NADPH oxidase 1 (NOX1) activity, by which the expanded SCA7 disease protein ATXN7 causes metabolic dysregulation. The NOX1 protein is known to promote glycolytic activity, whereas the transcription factor p53 inhibits this process and instead promotes mitochondrial respiration. In a stable inducible PC12 model of SCA7, p53 and mutant ATXN7 co-aggregated and the transcriptional activity of p53 was reduced, resulting in a 50% decrease of key p53 target proteins, like AIF and TIGAR. In contrast, the expression of NOX1 was increased approximately 2 times in SCA7 cells. Together these alterations resulted in a decreased respiratory capacity, an increased reliance on glycolysis for energy production and a subsequent 20% reduction of ATP in SCA7 cells. Restoring p53 function, or suppressing NOX1 activity, both reversed the metabolic dysfunction and ameliorated mutant ATXN7 toxicity. These results hence not only enhance the understanding of the mechanisms causing metabolic dysfunction in SCA7 disease, but also identify NOX1 as a novel potential therapeutic target in SCA7 and possibly other polyQ diseases.

  1. 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.

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

    Science.gov (United States)

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

    2016-08-01

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

  3. 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

  4. Interleukin-8 in non-small cell lung carcinoma: relation with angiogenic pattern and p53 alterations.

    Science.gov (United States)

    Boldrini, Laura; Gisfredi, Silvia; Ursino, Silvia; Lucchi, Marco; Mussi, Alfredo; Basolo, Fulvio; Pingitore, Raffaele; Fontanini, Gabriella

    2005-12-01

    Progression of solid tumors, including NSCLC, is associated with increase in MVC (microvessel count), as a measure of tumor angiogenesis resulting from an imbalance between angiogenic factors and inhibitors. However, since tumor angiogenesis is a multi-step process under the control of various molecules, the mechanism of angiogenesis has not been fully clarified. Interleukin (IL)-8 has been shown to have a potential angiogenic effect in vitro and in vivo, and is overexpressed in several human solid cancers. Among the various angiogenic factors, vascular endothelial growth factor (VEGF) has been shown to correlate with a high MVC and with adverse prognosis in several human cancers, including NSCLC. Alterations of p53 suppressor gene are the most common genetic changes found in malignant tumors; several studies examined the link between aberrant p53 and angiogenesis in lung cancer, but only a few studies report data regarding a relation between p53 mutations and IL-8 expression. In this study we observed a correlation between IL-8 mRNA expression, intratumoral MVC and VEGF mRNA expression levels; furthermore, an aberrant p53 status was related to IL-8 expression. However, in our samples IL-8 levels did not significantly affect prognosis of NSCLC; more studies are required to elucidate the precise role of IL-8 in a large series of patients with non-small cell lung carcinoma.

  5. P53 and Rb tumor suppressor gene alterations in gastric cancer Alterações dos genes supressores tumorais p53 e Rb no câncer gástrico

    Directory of Open Access Journals (Sweden)

    Rejane Mattar

    2004-01-01

    Full Text Available Inactivation of tumor suppressor genes has been frequently observed in gastric carcinogenesis. Our purpose was to study the involvement of p53, APC, DCC, and Rb genes in gastric carcinoma. METHOD: Loss of heterozygosity of the p53, APC, DCC and Rb genes was studied in 22 gastric cancer tissues using polymerase chain reaction; single-strand conformation polymorphism of the p53 gene exons 5-6 and exons 7-8 was studied using 35S-dATP, and p53 expression was detected using a histological immunoperoxidase method with an anti-p53 clone. RESULTS AND DISCUSSION: No loss of heterozygosity was observed in any of these tumor suppressor genes; homozygous deletion was detected in the Rb gene in 23% (3/13 of the cases of intestinal-type gastric carcinoma. Eighteen (81.8% cases showed band mobility shifts in exons 5-6 and/or 7-8 of the p53 gene. The presence of the p53 protein was positive in gastric cancer cells in 14 cases (63.6%. Normal gastric mucosa showed negative staining for p53; thus, the immunoreactivity was likely to represent mutant forms. The correlation of band mobility shift and the immunoreactivity to anti-p53 was not significant (P = .90. There was no correlation of gene alterations with the disease severity. CONCLUSIONS: The inactivation of Rb and p53 genes is involved in gastric carcinogenesis in our environment. Loss of the Rb gene observed only in the intestinal-type gastric cancer should be further evaluated in association with Helicobacter pylori infection. The p53 gene was affected in both intestinal and diffuse histological types of gastric cancer.A inativação de genes supressores tumorais tem sido freqüentemente observada na carcinogênese gástrica. O nosso objetivo foi estudar o envolvimento dos genes p53, APC, DCC e Rb no câncer gástrico. MÉTODO: Vinte e dois casos de câncer gástrico foram estudados por PCR-LOH (reação de polimerase em cadeia- perda de alelo heterozigoto dos genes p53, APC, DCC e Rb; e por PCR-SSCP (rea

  6. Collecting duct carcinoma of the kidney is associated with CDKN2A deletion and SLC family gene up-regulation

    Science.gov (United States)

    Wei, Lei; Liu, Biao; Hu, Qiang; Miles, Kiersten Marie; Conroy, Jeffrey M.; Glenn, Sean T.; Costantini, Manuela; Magi-Galluzzi, Cristina; Signoretti, Sabina; Choueiri, Toni; Gallucci, Michele; Sentinelli, Steno; Fazio, Vito M.; Poeta, Maria Luana; Liu, Song; Morrison, Carl; Pili, Roberto

    2016-01-01

    The genetic landscape and molecular features of collecting duct carcinoma (CDC) of the kidney remain largely unknown. Herein, we performed whole exome sequencing (WES) and transcriptome sequencing (RNASeq) on 7 CDC samples (CDC1 −7). Among the 7 samples, 4 samples with matched non-tumor tissue were used for copy number analysis by SNP array data. No recurrent somatic SNVs were observed except for MLL, which was found to be mutated (p.V297I and p.F407C) in 2 samples. We identified somatic SNVs in 14 other cancer census genes including: ATM, CREBBP, PRDM1, CBFB, FBXW7, IKZF1, KDR, KRAS, NACA, NF2, NUP98, SS18, TP53, and ZNF521. SNP array data identified a CDKN2A homozygous deletion in 3 samples and SNV analysis showed a non-sense mutation of the CDKN2A gene with unknown somatic status. To estimate the recurrent rate of CDKN2A abnormalities, we performed FISH screening of additional samples and confirmed the frequent loss (62.5%) of CDKN2A expression. Since cisplatin based therapy is the common treatment option for CDC, we investigated the expression of solute carrier (SLC) family transporters and found 45% alteration. In addition, SLC7A11 (cystine transporter, xCT), a cisplatin resistance associated gene, was found to be overexpressed in 4 out of 5 (80%) cases of CDC tumors tested, as compared to matched non-tumor tissue. In summary, our study provides a comprehensive genomic analysis of CDC and identifies potential pathways suitable for targeted therapies. PMID:27144525

  7. p53 isoforms change p53 paradigm

    OpenAIRE

    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.

  8. Inhibition of SIRT1 Catalytic Activity Increases p53 Acetylation but Does Not Alter Cell Survival following DNA Damage

    Science.gov (United States)

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

    2006-01-01

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

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

    DEFF Research Database (Denmark)

    Perryman, L A; Blair, J M; Kingsley, E A;

    2006-01-01

    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...

  10. Alterations of EGFR, p53 and PTEN that mimic changes found in basal-like breast cancer promote transformation of human mammary epithelial cells.

    Science.gov (United States)

    Pires, Maira M; Hopkins, Benjamin D; Saal, Lao H; Parsons, Ramon E

    2013-03-01

    Breast cancer can be classified into different molecular subtypes with varying clinical and pathological characteristics. The basal-like breast cancer subtype represents one of the most aggressive and lethal types of breast cancer, and due to poor mechanistic understanding, it lacks targeted therapy. Many basal-like breast cancer patient samples display alterations of established drivers of cancer development, including elevated expression of EGFR, p53 inactivating mutations and loss of expression of the tumor suppressor PTEN; however, their contribution to human basal-like breast cancer pathogenesis remains ill-defined. Using non-transformed human mammary epithelial cells, we set out to determine whether altering EGFR, p53 and PTEN in different combinations could contribute to basal-like breast cancer progression through transformation of cells. Altering PTEN in combination with either p53 or EGFR in contrast to any of the single alterations caused increased growth of transformed colonies in soft agar. Concomitantly modifying all three genes led to the highest rate of cellular proliferation and the greatest degree of anchorage-independent colony formation. Results from our effort to engineer a model of BBC expressing alterations of EGFR, p53 and PTEN suggest that these changes are cooperative and likely play a causal role in basal-like breast cancer pathogenesis. Consideration should be given to targeting EGFR and restoring p53 and PTEN signaling simultaneously as a strategy for treatment of this subtype of breast cancer.

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

    NARCIS (Netherlands)

    O. Bruning; W. Bruins; M.J. Jonker; E. Zwart; T.V. van der Hoeven; J.L.A. Pennings; H. Rauwerda; A. de Vries; T.M. Breit

    2008-01-01

    Phosphorylation is important in p53-mediated DNA damage responses. After UV irradiation, p53 is phosphorylated specifically at murine residue Ser389. Phosphorylation mutant p53.S389A cells and mice show reduced apoptosis and compromised tumor suppression after UV irradiation. We investigated the und

  12. 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

  13. CDKN2A and MC1R variants found in Cypriot patients diagnosed with cutaneous melanoma

    Indian Academy of Sciences (India)

    GEORGIA KOULERMOU; CHRISTOS SHAMMAS; ANDREAS VASSILIOU; TASSOS C. KYRIAKIDES; CONSTANTINA COSTI; VASSOS NEOCLEOUS; LEONIDAS A. PHYLACTOU; MARIA PANTELIDOU

    2017-03-01

    The prevalence of genetic variants associated to cutaneous melanoma (CM) has never been determined within Cypriot melanomas. This study evaluates the frequency of variants in cyclin-dependent kinase inhibitor 2A (CDKN2A) andmelanocortin-1 receptor (MC1R) in 32 patients diagnosed with CM. Other characteristics and risk factors were also assessed. CDKN2A p.Ala148Thr was detected in three of 32 patients, while the control group revealed no variationswithin CDKN2A. MC1R screening in 32 patients revealed the following variations: p.Val60Leu in 11 patients, p.Arg142His in four patients, p.Thr314Thr in one patient, p.Arg160Trp in one patient, p.Val92Met/p.Thr314Thr in one patient andp.Val92Met/p.Arg142His/p.Thr314Thr in one patient. The control group revealed only p.Val60Leu (in 10 of 45 individuals), which is frequently found in general populations. Two unrelated patients carried CDKN2A p.Ala148Thr in combination with MC1R p.Arg142His, suggesting digenic inheritance that may provide evidence of different gene variants acting synergistically to contribute for CM development. This study confirms the presence of CDKN2A and MC1R variants among Cypriot melanomas and supports existing evidence of a role for these variants in susceptibility to melanoma.

  14. 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.

  15. 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.......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...

  16. Detection of Homozygous Deletions and Mutations in the CDKN2A Gene in Hydatidiform Moles

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Shuying Wu; Ying Gu; Yan Zhu; Xiaowei Zhang

    2008-01-01

    OBJECTIVE To investigate homozygous deletions and mutations in the CDKN2A gene (p16INK4a and p14ARF gene) in hydatidiform moles.METHODS A total of 38 hydatidiform mole samples and 30 villi samples were examined for homozygous deletions in the CDKN2A gene by PCR and for mutations by DHPLC.RESULTS I) Among 38 hydatidiform mole samples,homozygous deletions in the p16INK4a exon 1 were identified in 5 cases (13.2%), while no homozygous deletions were found in the p16INK4a exon 1 of 30 early-pregnancy samples. The rates of those deletions in hydatidiform compared to early-pregnancy villi samples was statistically significant (P = 0.036). Ii) No homozygous deletions in the p14ARF exon 1 or p16INK4a exon 2 were found in any of the hydatidiform moles or early-preganancy samples, iii)In all hydatidiform moles and early-pregnancy villi samples, no mutations were detected by DHPLC.CONCLUSION We suggest there may be a close correlation between homozygous deletions in the CDKN2A gene and occurrence of hydatidiform moles variation in the CDKN2A gene is mainly caused by homozygous deletions, while mutations may be not a major cause.

  17. ERCC2/XPD Lys751Gln alter DNA repair efficiency of platinum-induced DNA damage through P53 pathway.

    Science.gov (United States)

    Zhang, Guopei; Guan, Yangyang; Zhao, Yuejiao; van der Straaten, Tahar; Xiao, Sha; Xue, Ping; Zhu, Guolian; Liu, Qiufang; Cai, Yuan; Jin, Cuihong; Yang, Jinghua; Wu, Shengwen; Lu, Xiaobo

    2017-02-01

    Platinum-based treatment causes Pt-DNA adducts which lead to cell death. The platinum-induced DNA damage is recognized and repaired by the nucleotide excision repair (NER) system of which ERCC2/XPD is a critical enzyme. Single nucleotide polymorphisms in ERCC2/XPD have been found to be associated with platinum resistance. The aim of the present study was to investigate whether ERCC2/XPD Lys751Gln (rs13181) polymorphism is causally related to DNA repair capacity of platinum-induced DNA damage. First, cDNA clones expressing different genotypes of the polymorphism was transfected to an ERCC2/XPD defective CHO cell line (UV5). Second, all cells were treated with cisplatin. Cellular survival rate were investigated by MTT growth inhibition assay, DNA damage levels were investigated by comet assay and RAD51 staining. The distribution of cell cycle and the change of apoptosis rates were detected by a flow cytometric method (FCM). Finally, P53mRNA and phospho-P53 protein levels were further investigated in order to explore a possible explanation. As expected, there was a significantly increased in viability of UV5(ERCC2 (AA)) as compared to UV5(ERCC2 (CC)) after cisplatin treatment. The DNA damage level of UV5(ERCC2 (AA)) was significant decreased compared to UV5(ERCC2 (CC)) at 24 h of treatment. Mutation of ERCC2rs13181 AA to CC causes a prolonged S phase in cell cycle. UV5(ERCC2 (AA)) alleviated the apoptosis compared to UV5(ERCC2 (CC)), meanwhile P53mRNA levels in UV(ERCC2 (AA)) was also lower when compared UV5(ERCC2 (CC)). It co-incides with a prolonged high expression of phospho-P53, which is relevant for cell cycle regulation, apoptosis, and the DNA damage response (DDR). We concluded that ERCC2/XPD rs13181 polymorphism is possibly related to the DNA repair capacity of platinum-induced DNA damage. This functional study provides some clues to clarify the relationship between cisplatin resistance and ERCC2/XPDrs13181 polymorphism.

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

    OpenAIRE

    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...

  19. Alterations of p53 and p73 Genes in Lympho-Plasmacytic Diseases%淋巴组织肿瘤中p53、p73基因改变和表达及其意义

    Institute of Scientific and Technical Information of China (English)

    刘建惠; 姜玉珍; 徐文; 梁新悦

    2005-01-01

    目的:探讨淋巴组织肿瘤中p53、p73基因改变和异常表达情况及其意义.方法:采用PCR-SCP法、RT-CR法、REP法、免疫组化法分别检测26例急性淋巴细胞白血病(ALL)、12例多发性骨髓瘤(MM)及12例淋巴瘤(MLs)标本中p53、p73基因改变及异常表达情况.结果:(1)26例ALL中仅有3例检测到p53基因点突变,12例MM标本中2例p53基因突变.未发现p73基因突变;(2)p73mRNA在淋巴组织肿瘤中总的阴性表达率为24%;(3)10例ALL和3例NHL在p73基因外显子1启动子区的CpG岛高甲基化,而正常对照组和12例MM标本均无甲基化存在;(4)对照组p53蛋白均为阴性.26例ALL中,p53蛋白阳性者20例;7例中高度恶性NHL中6例p53蛋白阳性.结论: p53基因在淋巴组织肿瘤中的突变率较低;MLs中p53蛋白表达和恶性程度、临床分期相关;p73mRNA在ALL/NHL中存在较高的阴性表达,,而在MM为阳性表达;p73基因转录失活与p73基因外显子1CpG岛高甲基化有关,不存在基因的突变和缺失;p73基因异常可能在MM的发生、发展中不是一个重要的分子事件.

  20. 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...... (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...

  1. EZH2 expression in gliomas: Correlation with CDKN2A gene deletion/ p16 loss and MIB-1 proliferation index.

    Science.gov (United States)

    Purkait, Suvendu; Sharma, Vikas; Jha, Prerana; Sharma, Mehar Chand; Suri, Vaishali; Suri, Ashish; Sharma, B S; Sarkar, Chitra

    2015-10-01

    Enhancer of zeste homolog 2 (EZH2) mediated down-regulation of CDKN2A/p16 has been observed in cell lines as well as in a few carcinomas. However, there is no study correlating EZH2 expression with CDKN2A/p16 status in gliomas. Hence, the present study was conducted to evaluate EZH2 expression in astrocytic and oligodendroglial tumors and correlate with CDKN2A/p16 status as well as MIB-1 labeling index (LI). Gliomas of all grades (n = 118) were studied using immunohistochemistry to assess EZH2, p16 and MIB-1 LI and fluorescence in situ hybrization to evaluate CDKN2A gene status. EZH2 expression and CDKN2A homozygous deletion (HD) were both significantly more frequent in high-grade gliomas (HGG). Further, strong EZH2 expression (LI ≥ 25%) was significantly more common in HGGs without CDKN2A HD (48.7%; 19/39) as compared to cases with deletion (15.8%; 3/19). Loss of p16 expression was noted in 100% and 51.3% of CDKN2A deleted and non-deleted tumors, respectively. Notably, 80% (16/20) of the CDKN2A non-deleted HGGs with p16 loss had strong EZH2 expression, in contrast to only 15.8% (3/19) in the deleted group. Loss of p16 expression significantly correlated with MIB-1 LI, irrespective of EZH2 status. Thus, this study shows that EZH2 expression correlates with tumor grade in both astrocytic and oligodendroglial tumors and hence can be used as a diagnostic marker to differentiate between low and HGGs. Further, this is the first report demonstrating an inverse correlation of strong EZH2 expression with CDKN2A HD in HGGs. Loss of p16 protein expression is mostly attributable to CDKN2A HD and correlates significantly with MIB-1 LI. Notably, our study for the first time suggests a possible epigenetic mechanism of p16 loss in CDKN2A non-deleted HGGs mediated by strong EZH2 expression. A hypothetical model for control of proliferative activity in low versus HGGs is therefore proposed.

  2. 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.

  3. Diffuse large B-cell lymphomas with CDKN2A deletion have a distinct gene expression signature and a poor prognosis under R-CHOP treatment: a GELA study.

    Science.gov (United States)

    Jardin, Fabrice; Jais, Jean-Philippe; Molina, Thierry-Jo; Parmentier, Françoise; Picquenot, Jean-Michel; Ruminy, Philippe; Tilly, Hervé; Bastard, Christian; Salles, Gilles-André; Feugier, Pierre; Thieblemont, Catherine; Gisselbrecht, Christian; de Reynies, Aurelien; Coiffier, Bertrand; Haioun, Corinne; Leroy, Karen

    2010-08-19

    Genomic alterations play a crucial role in the development and progression of diffuse large B-cell lymphomas (DLBCLs). We determined gene copy number alterations (GCNAs) of TP53, CDKN2A, CDKN1B, BCL2, MYC, REL, and RB1 with a single polymerase chain reaction (PCR) assay (quantitative multiplex PCR of short fragments [QMPSF]) in a cohort of 114 patients with DLBCL to assess their prognostic value and relationship with the gene expression profile. Losses of TP53 and CDKN2A, observed in 8% and 35% of patients, respectively, were significantly associated with a shorter survival after rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) treatment, independently of the International Prognostic Index and of the cell of origin. Analysis of the 9p21 genomic region indicated that transcripts encoding p14ARF and p16INK4A were both disrupted in most patients with CDKN2A deletion. These patients predominantly had an activated B-cell profile and showed a specific gene expression signature, characterized by dysregulation of the RB/E2F pathway, activation of cellular metabolism, and decreased immune and inflammatory responses. These features may constitute the molecular basis sustaining the unfavorable outcome and chemoresistance of this DLBCL subgroup. Detection of TP53 and CDKN2A loss by QMPSF is a powerful tool that could be used for patient stratification in future clinical trials.

  4. The meta-analysis between p53 alteration and smoking, alcohol consumption in esophageal cancer among Chinese population%中国食管癌患者p53基因改变与吸烟、饮酒的Meta分析

    Institute of Scientific and Technical Information of China (English)

    张玉雪; 吴海燕; 李慧岩

    2011-01-01

    目的 探讨吸烟、饮酒与中国人群食管癌p53基因改变的关系.方法 在Medline和CNKI数据库中系统检索相关文献,应用Meta分析的方法 进行定量综合分析.结果 共纳入14篇文献,累积食管癌2108例,p53基因改变1142例,平均阳性率为54.2%.在中国人群中,吸烟与食管癌p53基因改变的合并OR值为1.61(95% CI:1.09-2.38),P=0.003;饮酒与食管癌p53基因改变的合并OR值为1.91(95% CI:1.44-2.53),P<0.001.结论 中国人群中,吸烟、饮酒均与食管癌p53基因改变有显著联系.%Objective To explore the association between smoking, alcohol consumption and p53 alteration in esophageal cancer among Chinese population. Method A systematic search was performed using the Medline and CNKI databases, and the eligible literatures were systematic reviewed. Results Fourteen studies were eligible for analysis,involving 2108 esophageal cancer cases and 1142( 54.2% )p53 alteration cases. Among Chinese population, the pooled OR for the association between smoking,alcohol drinking and p53 alteration in esophageal cancer were 1.61( 95% CI:l.09 - 2.38 ;P = 0.003 )and 1.91( 95 % CI:1.44 - 2.53 ;P < 0.001 ) , respectively. Conclusion The findings of this meta - analysis indicated that there were significant associations between smoking, alcohol consumption and p53 alteration in esophageal cancer among Chinese population.

  5. Lack of evidence for mutations or deletions in the CDKN2A/p16 and CDKN2B/p15 genes of Brazilian neuroblastoma patients

    Directory of Open Access Journals (Sweden)

    Bassi C.L.

    2004-01-01

    Full Text Available Neuroblastoma, the most common extracranial tumor in childhood, has a wide spectrum of clinical and biological features. The loss of heterozygosity within the 9p21 region has been reported as a prognostic factor. Two tumor suppressor genes located in this region, the CDKN2B/p15 and CDKN2A/p16 (cyclin-dependent kinase inhibitors 2B and 2A, respectively genes, play a critical role in cell cycle progression and are considered to be targets for tumor inactivation. We analyzed CDKN2B/p15 and CDKN2A/p16 gene alterations in 11 patients, who ranged in age from 4 months to 13 years (male/female ratio was 1.2:1. The most frequent stage of the tumor was stage IV (50%, followed by stages II and III (20% and stage I (10%. The samples were submitted to the multiplex PCR technique for homozygous deletion analysis and to single-strand conformation polymorphism and nucleotide sequencing for mutation analysis. All exons of both genes were analyzed, but no deletion was detected. One sample exhibited shift mobility specific for exon 2 in the CDKN2B/p15 gene, not confirmed by DNA sequencing. Homozygous deletions and mutations are not involved in the inactivation mechanism of the CDKN2B/p15 and CDKN2A/p16 genes in neuroblastoma; however, these two abnormalities do not exclude other inactivation pathways. Recent evidence has shown that the expression of these genes is altered in this disease. Therefore, other mechanisms of inactivation, such as methylation of promoter region and unproperly function of proteins, may be considered in order to estimate the real contribution of these genes to neuroblastoma genesis or disease progression.

  6. The MTAP-CDKN2A Locus Confers Susceptibility to a Naturally Occurring Canine Cancer

    Science.gov (United States)

    Shearin, Abigail L.; Hedan, Benoit; Cadieu, Edouard; Erich, Suzanne A.; Schmidt, Emmett V.; Faden, Daniel L.; Cullen, John; Abadie, Jerome; Kwon, Erika M.; Gröne, Andrea; Devauchelle, Patrick; Rimbault, Maud; Karyadi, Danielle M.; Lynch, Mary; Galibert, Francis; Breen, Matthew; Rutteman, Gerard R.; André, Catherine; Parker, Heidi G.; Ostrander, Elaine A.

    2012-01-01

    Background Advantages offered by canine population substructure, combined with clinical presentations similar to human disorders, makes the dog an attractive system for studies of cancer genetics. Cancers that have been difficult to study in human families or populations are of particular interest. Histiocytic sarcoma is a rare and poorly understood neoplasm in humans that occurs in 15–25% of Bernese Mountain Dogs (BMD). Methods Genomic DNA was collected from affected and unaffected BMD in North America (NA) and Europe. Both independent and combined genome wide association studies (GWAS) were used to identify cancer-associated loci. Fine mapping and sequencing narrowed the primary locus to a single gene region. Results Both populations shared the same primary locus, which features a single haplotype spanning MTAP and part of CDKN2A and is present in 96% of affected BMD. The haplotype is within the region homologous to human chromosome 9p21, which has been implicated in several types of cancer. Conclusions We present the first GWAS for HS in any species. The data identify an associated haplotype in the highly cited tumor suppressor locus near CDKN2A. These data demonstrate the power of studying distinctive malignancies in highly predisposed dog breeds. Impact Here, we establish a naturally-occurring model of cancer susceptibility due to CDKN2 dysregulation, thus providing insight regarding this cancer-associated, complex, and poorly understood genomic region. PMID:22623710

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

    Directory of Open Access Journals (Sweden)

    May Al-Maghrebi

    2016-07-01

    Full Text Available 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

  8. 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)

    Al-Maghrebi, May; 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

  9. A study on p53 gene alterations in esophageal squamous cell carcinoma and their correlation to common dietary risk factors among population of the Kashmir valley

    Institute of Scientific and Technical Information of China (English)

    Imtiyaz Murtaza; Dhuha Mushtaq; Mushtaq A Margoob; Amit Dutt; Nisar Ahmad Wani; Ishfaq Ahmad; Mohan Lal Bhat

    2006-01-01

    AIM: To systematically examine the extent of correlation of risk factors, such as age, consumed dietary habit and familial predisposition with somatic Tp53 molecular lesion causal to elevate carcinogenesis severity of esophageal squamous cell carcinoma (ESCC) among the Kashmiri population of Northern India.METHODS: All cases (n = 51) and controls (n = 150) were permanent residents of the Kashmir valley. Genetic alterations were determined in exons 5-8 of Tp53 tumor suppressor gene among 45 ESCC cases histologically confirmed by PCR-SSCP analysis. Data for individual cancer cases (n = 45) and inpatient controls (n = 150) with non-cancer disease included information on family history of cancer, thirty prevailing common dietary risk factors along with patient's age group. Correlation of genetic lesion in p53 exons to animistic data from these parameters was generated by Chi-square test to all 45 histologically confirmed ESCC cases along with healthy controls.RESULTS: Thirty-five of 45 (77.8%) histologically characterized tumor samples had analogous somatic mutation as opposed to 1 of 45 normal sample obtained from adjacent region from the same patient showed germline mutation. The SSCP analysis demonstrated that most common p53 gene alterations were found in exon 6 (77.7%), that did not correlate with the age of the individual and clinicopathological parameters but showed significant concordance (P < 0.05) with familial history of cancer (CD = 58), suggesting germline predisposition at an unknown locus, and dietary habit of consuming locally grown Brassica vegetable "Hakh" (CD = 19.5),red chillies (CD = 20.2), hot salty soda tea (CD = 2.37) and local baked bread (CD = 1.1).CONCLUSION: Our study suggests that somatic chromosomal mutations, especially in exon 6 of Tp53 gene, among esophageal cancer patients of an ethnically homogenous population of Kashmir valley are closely related to continued exposure to various common dietary risk factors, especially hot salty tea

  10. CDKN2A/p16INK4a expression is associated with vascular progeria in chronic kidney disease

    Science.gov (United States)

    Stenvinkel, Peter; Luttropp, Karin; McGuinness, Dagmara; Witasp, Anna; Rashid Qureshi, Abdul; Wernerson, Annika; Nordfors, Louise; Schalling, Martin; Ripsweden, Jonaz; Wennberg, Lars; Söderberg, Magnus; Bárány, Peter; Olauson, Hannes; Shiels, Paul G

    2017-01-01

    Patients with chronic kidney disease (CKD) display a progeric vascular phenotype linked to apoptosis, cellular senescence and osteogenic transformation. This has proven intractable to modelling appropriately in model organisms. We have therefore investigated this directly in man, using for the first time validated cellular biomarkers of ageing (CDKN2A/p16INK4a, SA-β-Gal) in arterial biopsies from 61 CKD patients undergoing living donor renal transplantation. We demonstrate that in the uremic milieu, increased arterial expression of CDKN2A/p16INK4a associated with vascular progeria in CKD, independently of chronological age. The arterial expression of CDKN2A/p16INK4a was significantly higher in patients with coronary calcification (p=0.01) and associated cardiovascular disease (CVD) (p=0.004). The correlation between CDKN2A/p16INK4a and media calcification was statistically significant (p=0.0003) after correction for chronological age. We further employed correlate expression of matrix Gla protein (MGP) and runt-related transcription factor 2 (RUNX2) as additional pathognomonic markers. Higher expression of CDKN2A/p16INK4a, RUNX2 and MGP were observed in arteries with severe media calcification. The number of p16INK4a and SA-β-Gal positive cells was higher in biopsies with severe media calcification. A strong inverse correlation was observed between CDKN2A/p16INK4a expression and carboxylated osteocalcin levels. Thus, impaired vitamin K mediated carboxylation may contribute to premature vascular senescence. PMID:28192277

  11. Alterations of p53 and PCNA in cancer and adjacent tissues from concurrent carcinomas of the esophagus and gastric cardia in the same patient in Linzhou, a high incidence area for esophageal cancer in northern China

    Institute of Scientific and Technical Information of China (English)

    Hong Chen; Li-Dong Wang; Mei Guo; She-Gan Gao; Hua-Qin Guo; Zong-Min Fan; Ji-Lin Li

    2003-01-01

    AIM: To characterize the alteration and significance of p53and PCNA in cancer and adjacent tissues of concurrent cancersfrom the esophagus and gastric cardia in the same patient.METHODS: P53 and PCNA protein accumulation in 25patients with concurrent cancers from the esophagus andgastric cardia (CC, concurrent carcinomas of esophagealsquamous cell carcinoma and gastric cardia adenocarcinoma)were detected by immunohistochemical method (ABC).RESULTS: In CC patients, both esophageal squamous cellcarcinoma (SCC) and gastric cardia adenocarcinoma (GCA)tissues showed different positive immunostaining extent ofp53 and PCNA protein (P>0.05). The positive immunostainingrates for p53 and PCNA were 60 % (15/25) and 92 % (23/25), respectively in SCC; and 40 % (10/25) and 88 % (22/25), respectively in GCA. "Diffuse" immunostaining patternwas frequently observed in both p53 and PCNA. Highcoincidence rates for p53 and PCNA positive staining wereobserved in SCC and GCA from the same patients, andaccounted for 56 % and 96 %. In SCC patients, with thelesions progressed from normal esophageal epithelium (NOR)to basal cell hyperplasia (BCH) to dysplasia (DYS) tocarcinomain situ (CIS) to SCC, the positive rates for p53were 27 %, 50 %, 50 %, 29 % and 72 %, and 55 %, 70 %,75 %, 71% and 93 % for PCNA, respectively. In GCA, withthe lesions progressed from normal gastric cardia epitheliumto DYS to CIS to GCA, the positive rates of p53 expressionwere 44 %, 27 %, 22 % and 36 % respectively, the differencewas not significant; the positive rates of PCNA proteinexpression were 67 %, 64 %, 67 % and 86 %, respectively.The x2 test, Fisher's Exact Test, Mantel-Haenszel x2 Testand Kappa Test were used for the statistics.CONCLUSION: The high coincident alterations for P53 andPCNA in SCC and GCA from the same patient indicate thepossibility of similar molecular basis, which providesimportant molecular basis and etiological clue for similargeographic distribution and risk factors in SCC and GCA.

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

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    López-Nevot Miguel

    2005-04-01

    Full Text Available Abstract Background 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 Methods We analysed 39 primary and metastatic melanomas and 9 melanoma cell lines by single-stranded conformational polymorphism (SSCP. Results 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. Conclusion 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.

  13. Microbial Regulation of p53 Tumor Suppressor.

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    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.

  14. Modeling Human Epithelial Ovarian Cancer in Mice by Alteration of Expression of the BRCA1 and/or p53 Genes

    Science.gov (United States)

    2008-02-01

    including high level chromosome damage, variable chromosome counts, rearrangements and multiclonal populations ( dicentrics , translocations...sarcoma arising in the p53LoxP/LoxP group, while not normal, generally had patterns of whole chromosome gains and losses consistent with aneuploidy and...many fewer regions of interstitial chromosomal gains/losses detected by aCGH as compared to tumors isolated from Brca1LoxP/LoxP;p53LoxP/LoxP mice

  15. OTUD5 regulates p53 stability by deubiquitinating p53.

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    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.

  16. 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.

  17. Genome-wide retroviral insertional tagging of genes involved in cancer in Cdkn2a-deficient mice.

    Science.gov (United States)

    Lund, Anders H; Turner, Geoffrey; Trubetskoy, Alla; Verhoeven, Els; Wientjens, Ellen; Hulsman, Danielle; Russell, Robert; DePinho, Ronald A; Lenz, Jack; van Lohuizen, Maarten

    2002-09-01

    We have used large-scale insertional mutagenesis to identify functional landmarks relevant to cancer in the recently completed mouse genome sequence. We infected Cdkn2a(-/-) mice with Moloney murine leukemia virus (MoMuLV) to screen for loci that can participate in tumorigenesis in collaboration with loss of the Cdkn2a-encoded tumor suppressors p16INK4a and p19ARF. Insertional mutagenesis by the latent retrovirus was synergistic with loss of Cdkn2a expression, as indicated by a marked acceleration in the development of both myeloid and lymphoid tumors. We isolated 747 unique sequences flanking retroviral integration sites and mapped them against the mouse genome sequence databases from Celera and Ensembl. In addition to 17 insertions targeting gene loci known to be cancer-related, we identified a total of 37 new common insertion sites (CISs), of which 8 encode components of signaling pathways that are involved in cancer. The effectiveness of large-scale insertional mutagenesis in a sensitized genetic background is demonstrated by the preference for activation of MAP kinase signaling, collaborating with Cdkn2a loss in generating the lymphoid and myeloid tumors. Collectively, our results show that large-scale retroviral insertional mutagenesis in genetically predisposed mice is useful both as a system for identifying genes underlying cancer and as a genetic framework for the assignment of such genes to specific oncogenic pathways.

  18. 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.

  19. Loss of p16 expression and copy number changes of CDKN2A in a spectrum of spitzoid melanocytic lesions.

    Science.gov (United States)

    Harms, Paul W; Hocker, Thomas L; Zhao, Lili; Chan, May P; Andea, Aleodor A; Wang, Min; Harms, Kelly L; Wang, Michael L; Carskadon, Shannon; Palanisamy, Nallasivam; Fullen, Douglas R

    2016-12-01

    Spitzoid melanocytic lesions, including Spitz nevi (benign), spitzoid melanoma (malignant), and borderline atypical Spitz tumors (ASTs), frequently present challenges for accurate diagnosis and prognosis. Evaluation for loss of the tumor suppressor p16, encoded by CDKN2A gene on chromosome 9p21.3, has been proposed to be useful for evaluation of spitzoid melanocytic lesions. However, reports on the utility of p16 immunohistochemistry for spitzoid lesions have been conflicting, and few studies have directly compared p16 immunohistochemistry with fluorescence in situ hybridization (FISH) for CDKN2A genomic status. We analyzed a spectrum of benign (n=24), borderline (n=27), and malignant (n=19) spitzoid lesions for p16 protein expression by immunohistochemistry and CDKN2A copy number by FISH. Immunohistochemistry was evaluated by 2 scoring methods: H score and 2-tiered score (positive or negative for p16 loss). By immunohistochemistry, loss of p16 expression was not observed in Spitz nevi (0/24) but was seen in ASTs (7/27; 26%) and spitzoid melanomas (3/19; 16%). By H score, p16 expression was significantly higher in Spitz nevi relative to ASTs or spitzoid melanomas. Similarly, copy number aberrations of CDKN2A by FISH were absent in Spitz nevi but were found in 2 (9.5%) of 21 ASTs and 4 (33%) of 12 spitzoid melanomas. Our findings from this large cohort suggest that p16 aberrations are highly specific for borderline and malignant spitzoid neoplasms relative to Spitz nevi. Similar to ASTs, p16 loss in spitzoid melanomas may occur in the presence or absence of genomic CDKN2A loss.

  20. Genetic Alterations in K-ras and p53 Cancer Genes in Lung Neoplasms From B6C3F1 Mice Exposed to Cumene

    OpenAIRE

    Hong, Hue-Hua L.; Ton, Thai-Vu T.; Kim, Yongbaek; Wakamatsu, Nobuko; Clayton, Natasha P.; Chan, Po-Chuen; Sills, Robert C.; Lahousse, Stephanie A.

    2008-01-01

    The incidences of alveolar/bronchiolar adenomas and carcinomas in cumene-treated B6C3F1 mice were significantly greater than those of the controls. We evaluated these lung neoplasms for point mutations in the K-ras and p53 genes that are often mutated in humans. K-ras and p53 mutations were detected by cycle sequencing of PCR-amplified DNA isolated from paraffin-embedded neoplasms. K-ras mutations were detected in 87 % cumene-induced lung neoplasms, and the predominant mutations were exon 1 c...

  1. Genetic alterations in K-ras and p53 cancer genes in lung neoplasms from B6C3F1 mice exposed to cumene.

    Science.gov (United States)

    Hong, Hue-Hua L; Ton, Thai-Vu T; Kim, Yongbaek; Wakamatsu, Nobuko; Clayton, Natasha P; Chan, Po-Chuen; Sills, Robert C; Lahousse, Stephanie A

    2008-07-01

    The incidences of alveolar/bronchiolar adenomas and carcinomas in cumene-treated B6C3F1 mice were significantly greater than those of the control animals. We evaluated these lung neoplasms for point mutations in the K-ras and p53 genes that are often mutated in humans. K-ras and p53 mutations were detected by cycle sequencing of PCR-amplified DNA isolated from paraffin-embedded neoplasms. K-ras mutations were detected in 87% of cumene-induced lung neoplasms, and the predominant mutations were exon 1 codon 12 G to T transversions and exon 2 codon 61 A to G transitions. P53 protein expression was detected by immunohistochemistry in 56% of cumene-induced neoplasms, and mutations were detected in 52% of neoplasms. The predominant mutations were exon 5, codon 155 G to A transitions, and codon 133 C to T transitions. No p53 mutations and one of seven (14%) K-ras mutations were detected in spontaneous neoplasms. Cumene-induced lung carcinomas showed loss of heterozygosity (LOH) on chromosome 4 near the p16 gene (13%) and on chromosome 6 near the K-ras gene (12%). No LOH was observed in spontaneous carcinomas or normal lung tissues examined. The pattern of mutations identified in the lung tumors suggests that DNA damage and genomic instability may be contributing factors to the mutation profile and development of lung cancer in mice exposed to cumene.

  2. 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

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

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    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

  4. Sulphur alters NFκB-p300 cross-talk in favour of p53-p300 to induce apoptosis in non-small cell lung carcinoma.

    Science.gov (United States)

    Saha, Shilpi; Bhattacharjee, Pushpak; Guha, Deblina; Kajal, Kirti; Khan, Poulami; Chakraborty, Sreeparna; Mukherjee, Shravanti; Paul, Shrutarshi; Manchanda, Rajkumar; Khurana, Anil; Nayak, Debadatta; Chakrabarty, Rathin; Sa, Gaurisankar; Das, Tanya

    2015-08-01

    Adverse side effects of chemotherapy during cancer treatment have shifted considerable focus towards therapies that are not only targeted but are also devoid of toxic side effects. We evaluated the antitumorigenic activity of sulphur, and delineated the molecular mechanisms underlying sulphur-induced apoptosis in non-small cell lung carcinoma (NSCLC) cells. A search for the underlying mechanism revealed that the choice between the two cellular processes, NFκBp65-mediated survival and p53-mediated apoptosis, was decided by the competition for a limited pool of transcriptional coactivator protein p300 in NSCLC cells. In contrast, sulphur inhibited otherwise upregulated survival signaling in NSCLC cells by perturbing the nuclear translocation of p65NFκB, its association with p300 histone acetylase, and subsequent transcription of Bcl-2. Under such anti-survival condition, induction of p53-p300 cross-talk enhanced the transcriptional activity of p53 and intrinsic mitochondrial death cascade. Overall, the findings of this preclinical study clearly delineated the molecular mechanism underlying the apoptogenic effect of the non-toxic homeopathic remedy, sulphur, in NSCLC cells.

  5. p53 Cellular Localization and Function in Neuroblastoma

    Science.gov (United States)

    Tweddle, Deborah A.; Malcolm, Archie J.; Cole, Michael; Pearson, Andrew D.J.; Lunec, John

    2001-01-01

    This study investigated the hypothesis that p53 accumulation in neuroblastoma, in the absence of mutation, is associated with functional inactivation, which interferes with downstream mediators of p53 function. To test this hypothesis, p53 expression, location, and functional integrity was examined in neuroblastoma by irradiating 6 neuroblastoma cell lines and studying the effects on p53 transcriptional function, cell cycle arrest, and induction of apoptosis, together with the transcriptional function of p53 after irradiation in three ex vivo primary, untreated neuroblastoma tumors. p53 sequencing showed five neuroblastoma cell lines, two of which were MYCN-amplified, and that all of the tumors were wild-type for p53. p53 was found to be predominantly nuclear before and after irradiation and to up-regulate the p53 responsive genes WAF1 and MDM2 in wild-type p53 cell lines and a poorly-differentiated neuroblastoma, but not a differentiating neuroblastoma or the ganglioneuroblastoma part of a nodular ganglioneuroblastoma in short term culture. This suggests intact p53 transcriptional activity in proliferating neuroblastoma. Irradiation of wild-type p53 neuroblastoma cell lines led to G1 cell cycle arrest in cell lines without MYCN amplification, but not in those with MYCN amplification, despite induction of WAF1. This suggests MYCN amplification may alter downstream mediators of p53 function in neuroblastoma. PMID:11395384

  6. The presence of the intron 3 16 bp duplication polymorphism of p53 (rs17878362) in breast cancer is associated with a low Δ40p53:p53 ratio and better outcome.

    Science.gov (United States)

    Morten, Brianna C; Wong-Brown, Michelle W; Scott, Rodney J; Avery-Kiejda, Kelly A

    2016-01-01

    Breast cancer is the most common female cancer, but it has relatively low rates of p53 mutations, suggesting other mechanisms are responsible for p53 inactivation. We have shown that the p53 isoform, Δ40p53, is highly expressed in breast cancer, where it may contribute to p53 inactivation. Δ40p53 can be produced by alternative splicing of p53 in intron 2 and this is regulated by the formation of G-quadruplex structures in p53 intron 3, from which the nucleotides forming these structures overlap with a common polymorphism, rs17878362. rs17878362 alters p53 splicing to decrease fully spliced p53 messenger RNA (mRNA) in vitro following ionizing radiation and this in turn alters Δ40p53:p53. Hence, the presence of rs17878362 may be important in regulating Δ40p53:p53 in breast cancer. This study aimed to determine if rs17878362 was associated with altered Δ40p53 and p53 expression and outcome in breast cancer. We sequenced p53 in breast tumours from 139 patients and compared this with Δ40p53 and p53 mRNA expression. We found that the ratio of Δ40p53:p53 was significantly lower in tumours homozygous for the polymorphic A2 allele compared with those who were wild-type (A1/A1). Furthermore, there was a lower proportion of breast cancers carrying the A2 allele from patients who subsequently developed metastasis compared with those that did not. Finally, we show that patients whose tumours carried the polymorphic A2 allele had significantly better disease-free survival. These results show that rs17878362 is associated with a low Δ40p53:p53 ratio in breast cancer and that this is associated with better outcome.

  7. Serum starvation and thymidine double blocking achieved efficient cell cycle synchronization and altered the expression of p27, p53, bcl-2 in canine breast cancer cells.

    Science.gov (United States)

    Tong, Jinjin; Sun, Dongdong; Yang, Chao; Wang, Yingxue; Sun, Sichao; Li, Qing; Bao, Jun; Liu, Yun

    2016-04-01

    Cell synchronization is an approach to obtain cell populations of the same stage, which is a prerequisite to studying the regulation of cell cycle progression in vivo. Serum starvation and thymidine double blocking (TdR) are two important practices in studying cell cycle synchronization. However, their effects on canine cancer cells as well as the regulatory mechanisms by these two methods are poorly understood. In this study, we determined the optimum conditions of serum starvation and TdR and their effects on cell cycle synchronization. We further explored the involvement of PI3K/Akt signaling pathway in the cell cycle synchronization by investigating the expression of three key genes (p27, p53 and bcl-2). Serum starvation resulted in a reversible cell cycle arrest and synchronously progress through G0/G1. The highest percentage of CHMm cells (87.47%) in G0/G1 stage was obtained after 42 h incubation with 0.5% fetal bovine serum (FBS). TdR double blocking could arrest 98.9% of CHMm cells in G1/S phase (0 h of release), and could arrest 93.74% of CHMm cells in S phase after 4h of release. We also found that the p27, p53, bcl-2 genes were most highly expressed in G0/G1 phase. Our current work revealed that serum starvation and TdR methods could achieve sufficient synchronization of CHMm cells. Moreover, the expression of p27, p53 and bcl-2 genes was related to cyclical movements and apoptosis. Our results will provide a new insight into cell cycle regulation and reprogramming of canine cancer cells induced by serum starvation and TdR blocking.

  8. 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

  9. 肺癌患者呼出气冷凝液中基因微卫星改变和p53基因变异的检测及其意义%Significance of detection of chromosome microsatellite alterations and p53 gene mutation in exhaled breath condensate of lung cancer patients

    Institute of Scientific and Technical Information of China (English)

    冯哲敏; 陈建荣; 蔡映云

    2009-01-01

    呼出气冷凝液(exhaled breath condensate,EBC)检测是一种新的肺部病变诊断技术.通过检测EBC中相关基因.从而寻找早期诊断肺癌的新方法是目前肺癌研究的热点.采用聚合酶链式反应,对肺癌患者EBC中3号染色体短臂上基因的微卫星异常以及p53基因变异进行检测,结果发现肺癌患者EBC中基因微卫星改变和p53基因变异较正常对照者阳性率明显为高.目前对于EBC基因检测尚属探索阶段,但随着检测技术的不断完善,检测EBC中肺癌的基因标志物是一个较为有希望提高肺癌早期诊断率的方法.%Detection of the exhaled breath condensate(EBC) is a new diagnosis for lung disease.Detecting gene mutation in EBC of lung cancer patients as a potential method of diagnosing lung cancer in early period has become a hot spot in lung cancer research. Some researches, which detect gene mutation in EBC by using polymerase chain reaction, demonstrate that positive rates of p53 gene mutation and chromosome microsatellite alterations in chromosomal region 3p of lung cancer patients are higher than those of healthy peoples. Detecting gene mutation in EBC is still in research stage. However, as the continual development of detecting technique,it is expected to raise the early diagnosis of lung carcinoma.

  10. 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.

  11. Molecular profiling uncovers a p53-associated role for microRNA-31 in inhibiting the proliferation of serous ovarian carcinomas and other cancers

    Science.gov (United States)

    Creighton, Chad J.; Fountain, Michael D.; Yu, Zhifeng; Nagaraja, Ankur K.; Zhu, Huifeng; Khan, Mahjabeen; Olokpa, Emuejevoke; Zariff, Azam; Gunaratne, Preethi H.; Matzuk, Martin M.; Anderson, Matthew L.

    2010-01-01

    MicroRNAs (miRNAs) regulate complex patterns of gene expression, and the relevance of altered miRNA expression to ovarian cancer remains to be elucidated. By comprehensively profiling expression of miRNAs and mRNAs in serous ovarian tumors and cell lines and normal ovarian surface epithelium, we identified hundreds of potential miRNA-mRNA targeting associations underlying cancer. Functional overexpression of miR-31, the most underexpressed miRNA in serous ovarian cancer, repressed predicted miR-31 gene targets including cell cycle regulator E2F2. MIR31 and CDKN2A, which encodes p14ARF and p16INK4A, are located at 9p21.3, a genomic region commonly deleted in ovarian and other cancers. p14ARF promotes p53 activity, and E2F2 overexpression in p53 wild-type cells normally leads via p14ARF to an induction of p53-dependent apoptosis. In a number of serous cancer cell lines with a dysfunctional p53 pathway (i.e., OVCAR8, OVCA433, and SKOV3), miR-31 overexpression inhibited proliferation and induced apoptosis; however, in other lines (i.e., HEY and OVSAYO) with functional p53, miR-31 had no effect. Additionally, the osteosarcoma cell line U2OS and the prostate cancer cell line PC3 (p14ARF-deficient and p53-deficient, respectively) were also sensitive to miR-31. Furthermore, miR-31 overexpression induced a global gene expression pattern in OVCAR8 associated with better prognosis in tumors from patients with advanced stage serous ovarian cancer, potentially impacting many genes underlying disease progression. Our findings reveal that loss of miR-31 is associated with defects in the p53 pathway and functions in serous ovarian cancer and other cancers, suggesting that patients with cancers deficient in p53 activity might benefit from therapeutic delivery of miR-31. PMID:20179198

  12. 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.

  13. Pre-transplant CDKN2A expression in kidney biopsies predicts renal function and is a future component of donor scoring criteria.

    Directory of Open Access Journals (Sweden)

    Marc Gingell-Littlejohn

    Full Text Available CDKN2A is a proven and validated biomarker of ageing which acts as an off switch for cell proliferation. We have demonstrated previously that CDKN2A is the most robust and the strongest pre-transplant predictor of post-transplant serum creatinine when compared to "Gold Standard" clinical factors, such as cold ischaemic time and donor chronological age. This report shows that CDKN2A is better than telomere length, the most celebrated biomarker of ageing, as a predictor of post-transplant renal function. It also shows that CDKN2A is as strong a determinant of post-transplant organ function when compared to extended criteria (ECD kidneys. A multivariate analysis model was able to predict up to 27.1% of eGFR at one year post-transplant (p = 0.008. Significantly, CDKN2A was also able to strongly predict delayed graft function. A pre-transplant donor risk classification system based on CDKN2A and ECD criteria is shown to be feasible and commendable for implementation in the near future.

  14. Uropathogenic E. coli infection provokes epigenetic downregulation of CDKN2A (p16INK4A) in uroepithelial cells.

    Science.gov (United States)

    Tolg, Cornelia; Sabha, Nesrin; Cortese, Rene; Panchal, Trupti; Ahsan, Alya; Soliman, Ashraf; Aitken, Karen J; Petronis, Arturas; Bägli, Darius J

    2011-06-01

    Host cell and bacterial factors determine severity and duration of infections. To allow for bacteria pathogenicity and persistence, bacteria have developed mechanisms that modify expression of host genes involved in cell cycle progression, apoptosis, differentiation and the immune response. Recently, Helicobacter pylori infection of the stomach has been correlated with epigenetic changes in the host genome. To identify epigenetic changes during Escherichia coli induced urinary tract infection (UTI), we developed an in vitro model of persistent infection of human uroepithelial cells with uropathogenic E. coli (UPEC), resulting in intracellular bacteria colonies. Cells inoculated with FimH-negative E. coli (N-UPEC) that are not internalized and non-inoculated cells were used as controls. UPEC infection significantly induced de novo methyltransferase (DNMT) activity (12.5-fold P=0.002 UPEC vs non-inoculated and 250-fold P=0.001 UPEC vs N-UPEC inoculated cells) and Dnmt1 RNA expression (6-fold P=0.04 UPEC vs non-inoculated cells) compared with controls. DNMT1 protein levels were significantly increased in three uroepithelial cell lines (5637, J82, HT-1197) in response to UPEC infection as demonstrated by confocal analysis. Real-time PCR analysis of candidate genes previously associated with bacteria infection and/or innate immunity, revealed UPEC-induced downregulation of the tumor suppressor gene CDKN2A (3.3-fold P=0.007 UPEC vs non-inoculated and 3.3-fold P=0.001 UPEC vs N-UPEC) and the DNA repair gene MGMT (9-fold P=0.03 UPEC vs non-inoculated). Expression of CDH1, MLH1, DAPK1 and TLR4 was not affected. Pyrosequencing of CDKN2A and MGMT CpG islands revealed increased methylation in CDKN2A exon 1 (3.8-fold P=0.04 UPEC vs N-UPEC and UPEC vs non-inoculated). Methylation of MGMT was not affected. UPEC-induced methylation of CDKN2A exon 1 may increase bladder cancer and presage UTI risk, and be useful as a biological marker for UTI susceptibility or recurrence.

  15. 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...

  16. 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

    There is increasing evidence from genome-wide association studies for a strong inherited genetic basis of susceptibility to acute lymphoblastic leukaemia (ALL) in children, yet the effects of protein-coding variants on ALL risk have not been systematically evaluated. Here we show a missense variant...... 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 genetic variation...

  17. p53 and H-ras mutations and microsatellite instability in renal pelvic carcinomas of NON / Shi mice treated with N-butyl-N-(4-hydroxybutyl)-nitrosamine: different genetic alteration from urinary bladder carcinoma.

    Science.gov (United States)

    Gen, H; Yamamoto, S; Morimura, K; Min, W; Mitsuhashi, M; Murai, T; Mori, S; Hosono, M; Oohara, T; Makino, S; Wanibuchi, H; Fukushima, S

    2001-12-01

    We previously reported p53 mutations to be frequent (greater than 70%), whereas both H-ras mutations and microsatellite instability (MSI) were infrequent (about 10%), in urinary bladder carcinomas (UBCs) and their metastatic foci in the N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced mouse urothelial carcinogenesis model. In the present study, an analysis of p53 and H-ras mutations as well as MSI was performed on 12 renal pelvic carcinomas (RPCs) and 8 metastatic or invading foci produced by the same experimental procedure. Histologically, 10 of the RPCs were transitional cell carcinomas and the remaining 2 were squamous cell carcinomas. p53 mutations were infrequent and only found in one primary RPC (8%), its metastatic foci and an invading lesion in another animal (in a total 2 of 12; 17%). H-ras mutations were slightly more frequent (found in 3 of 12 animals; 25%), 4 of 5 involving codon 44, GTG to GCG, not a hot-spot reported for human cancers. In two cases, H-ras mutations were confined to lung metastasis and not detectable in their primary RPCs. MSI analysis was available for 6 pairs of primary RPCs and their metastatic foci, and 4 animals (67%) had MSI at one or more microsatellite loci. Overall, the distribution of genetic alterations differed from that in UBCs produced by the same experimental protocol. The results thus suggest that different genetic pathways may participate in carcinogenesis of the upper and lower urinary tract due to BBN.

  18. p53 as a target for the treatment of cancer.

    Science.gov (United States)

    Duffy, Michael J; Synnott, Naoise C; McGowan, Patricia M; Crown, John; O'Connor, Darran; Gallagher, William M

    2014-12-01

    TP53 (p53) is the most frequently mutated gene in cancer, being altered in approximately 50% of human malignancies. In most, if not all, cancers lacking mutation, wild-type (WT) p53 is inactivated by interaction with cellular (MDM2/MDM4) or viral proteins, leading to its degradation. Because of its near universal alteration in cancer, p53 is an attractive target for the development of new targeted therapies for this disease. However, until recently, p53 was widely regarded as ‘‘undruggable’’. This situation has now changed, as several compounds have become available that can restore wild-type properties to mutant p53 (e.g., PRIMA-1 and PRIMA-1MET). Other compounds are available that prevent the binding of MDM2/MDM4 to WT p53, thereby blocking its degradation (e.g., nutlins). Anti-mutant p53 compounds are potentially most useful in cancers with a high prevalence of p53 mutations. These include difficult-totreat tumors such as high grade serous ovarian cancer, triple-negative breast cancer and squamous lung cancer. MDM2/4 antagonists, on the other hand, are likely to be efficacious in malignancies in which MDM2 or MDM4 is overexpressed such as sarcomas, neuroblastomas and specific childhood leukemias. Presently, early clinical trials are ongoing evaluating the anti-mutant p53 agent, PRIMA-1MET, and specific MDM2–p53 nutlin antagonists.

  19. Disordered methionine metabolism in MTAP/CDKN2A-deleted cancers leads to dependence on PRMT5.

    Science.gov (United States)

    Mavrakis, Konstantinos J; McDonald, E Robert; Schlabach, Michael R; Billy, Eric; Hoffman, Gregory R; deWeck, Antoine; Ruddy, David A; Venkatesan, Kavitha; Yu, Jianjun; McAllister, Gregg; Stump, Mark; deBeaumont, Rosalie; Ho, Samuel; Yue, Yingzi; Liu, Yue; Yan-Neale, Yan; Yang, Guizhi; Lin, Fallon; Yin, Hong; Gao, Hui; Kipp, D Randal; Zhao, Songping; McNamara, Joshua T; Sprague, Elizabeth R; Zheng, Bing; Lin, Ying; Cho, Young Shin; Gu, Justin; Crawford, Kenneth; Ciccone, David; Vitari, Alberto C; Lai, Albert; Capka, Vladimir; Hurov, Kristen; Porter, Jeffery A; Tallarico, John; Mickanin, Craig; Lees, Emma; Pagliarini, Raymond; Keen, Nicholas; Schmelzle, Tobias; Hofmann, Francesco; Stegmeier, Frank; Sellers, William R

    2016-03-11

    5-Methylthioadenosine phosphorylase (MTAP) is a key enzyme in the methionine salvage pathway. The MTAP gene is frequently deleted in human cancers because of its chromosomal proximity to the tumor suppressor gene CDKN2A. By interrogating data from a large-scale short hairpin RNA-mediated screen across 390 cancer cell line models, we found that the viability of MTAP-deficient cancer cells is impaired by depletion of the protein arginine methyltransferase PRMT5. MTAP-deleted cells accumulate the metabolite methylthioadenosine (MTA), which we found to inhibit PRMT5 methyltransferase activity. Deletion of MTAP in MTAP-proficient cells rendered them sensitive to PRMT5 depletion. Conversely, reconstitution of MTAP in an MTAP-deficient cell line rescued PRMT5 dependence. Thus, MTA accumulation in MTAP-deleted cancers creates a hypomorphic PRMT5 state that is selectively sensitized toward further PRMT5 inhibition. Inhibitors of PRMT5 that leverage this dysregulated metabolic state merit further investigation as a potential therapy for MTAP/CDKN2A-deleted tumors.

  20. 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.

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

    OpenAIRE

    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...

  2. Reactivation of mutant p53 by capsaicin, the major constituent of peppers

    OpenAIRE

    2016-01-01

    Background Mutations in the p53 oncosuppressor gene are highly frequent in human cancers. These alterations are mainly point mutations in the DNA binding domain of p53 and disable p53 from transactivating target genes devoted to anticancer activity. Mutant p53 proteins are usually more stable than wild-type p53 and may not only impair wild-type p53 activity but also acquire pro-oncogenic functions. Therefore, targeting mutant p53 to clear the hyperstable proteins or change p53 conformation to...

  3. Usefulness of p16/CDKN2A fluorescence in situ hybridization and BAP1 immunohistochemistry for the diagnosis of biphasic mesothelioma.

    Science.gov (United States)

    Wu, Di; Hiroshima, Kenzo; Yusa, Toshikazu; Ozaki, Daisuke; Koh, Eitetsu; Sekine, Yasuo; Matsumoto, Shinji; Nabeshima, Kazuki; Sato, Ayuko; Tsujimura, Tohru; Yamakawa, Hisami; Tada, Yuji; Shimada, Hideaki; Tagawa, Masatoshi

    2017-02-01

    Malignant mesothelioma is a highly aggressive neoplasm, and the histologic subtype is one of the most reliable prognostic factors. Some biphasic mesotheliomas are difficult to distinguish from epithelioid mesotheliomas with atypical fibrous stroma. The aim of this study was to analyze p16/CDKN2A deletions in mesotheliomas by fluorescence in situ hybridization (FISH) and BAP1 immunohistochemistry to evaluate their potential role in the diagnosis of biphasic mesothelioma. We collected 38 cases of pleural mesotheliomas. The results of this study clearly distinguished 29 cases of biphasic mesothelioma from 9 cases of epithelioid mesothelioma. The proportion of biphasic mesotheliomas with homozygous deletions of p16/CDKN2A in total was 96.6% (28/29). Homozygous deletion of p16/CDKN2A was observed in 18 (94.7%) of 19 biphasic mesotheliomas with 100% concordance of the p16/CDKN2A deletion status between the epithelioid and sarcomatoid components in each case. Homozygous deletion of the p16/CDKN2A was observed in 7 (77.8%) of 9 epithelioid mesotheliomas but not in fibrous stroma. BAP1 loss was observed in 5 (38.5%) of 13 biphasic mesotheliomas and in both epithelioid and sarcomatoid components. BAP1 loss was observed in 5 (62.5%) of 8 epithelioid mesotheliomas but not in fibrous stroma. Homozygous deletion of p16/CDKN2A is common in biphasic mesotheliomas, and the analysis of only one component of mesothelioma is sufficient to show that the tumor is malignant. However, compared with histology alone, FISH analysis of the p16/CDKN2A status and BAP1 immunohistochemistry in the spindled mesothelium provide a more objective means to differentiate between biphasic mesothelioma and epithelioid mesothelioma with atypical stromal cells.

  4. BAP1 immunohistochemistry has limited prognostic utility as a complement of CDKN2A (p16) fluorescence in situ hybridization in malignant pleural mesothelioma.

    Science.gov (United States)

    M McGregor, Stephanie; McElherne, James; Minor, Agata; Keller-Ramey, Jennifer; Dunning, Ryan; Husain, Aliya N; Vigneswaran, Wickii; Fitzpatrick, Carrie; Krausz, Thomas

    2017-02-01

    BRCA-associated protein 1 (BAP1) immunohistochemistry (IHC) and CDKN2A (p16) fluorescence in situ hybridization (FISH) have shown clinical utility in confirming the diagnosis of malignant pleural mesothelioma (MPM), but the role for using these 2 markers to guide clinical management is not yet clear. Although p16 loss is predictive of poor prognosis, there is controversy as to whether BAP1 loss is predictive of a more favorable prognosis; how these results interact with one another has not been explored. We performed CDKN2A FISH on a previously published tissue microarray on which we had performed BAP1 IHC, revealing combined BAP1/p16 status for 93 MPM cases. As expected, BAP1 IHC in combination with CDKN2A FISH resulted in high sensitivity (84%) and specificity (100%) for MPM, and p16 loss was an independent predictor of poor survival (hazard ratio, 2.2553; P = .0135). There was no association between BAP1 loss and p16 loss, as 26%, 28%, 30%, and 16% of overall cases demonstrated loss of BAP1 alone, loss of p16 alone, loss of both BAP1 and p16, or neither abnormality, respectively. Although multivariate analysis demonstrated that BAP1 IHC is not an independent predictor of prognosis, when viewed in combination with homozygous CDKN2A deletion, risk stratification was evident. More specifically, patients with CDKN2A disomy and loss of BAP1 expression had improved outcomes compared with those with CDKN2A disomy and retained BAP1 expression (hazard ratio, 0.2286; P = .0017), and this finding was notably evident among epithelioid cases. We conclude that BAP1 IHC provides prognostic information within the context of CDKN2A FISH that may have clinical utility beyond diagnosis.

  5. CDKN2A (p16) mRNA decreased expression is a marker of poor prognosis in malignant high-grade glioma.

    Science.gov (United States)

    Sibin, M K; Bhat, Dhananjaya I; Narasingarao, K V L; Lavanya, Ch; Chetan, G K

    2015-09-01

    Human high-grade glioma is heterogeneous in nature based on pathological and genetic profiling. Various tumour suppressor gene alterations are considered as prognostic markers in high-grade glioma. Gene expression of CDKN2A (p16) is used in various cancers as a prognostic biomarker along with methylation and deletion status of this gene. Expression levels of p16 mRNA were not studied as a biomarker in gliomas before. In this study, we have performed mRNA quantification analysis on 48 high-grade glioma tissues and checked for a possible prognostic role. The decreased expression of p16 mRNA in majority of the tumour tissues (57.1 %) was observed when compared to control tissues (P = 0.02). mRNA expression level was correlated with clinical variables also. p16 deletion status and BMI1 mRNA expression were also considered for comparison. p16 mRNA was negatively correlated with the BMI1 mRNA (P = p16 deletion. p16 mRNA expression, midline shift in MRI and tumour type were able to predict patient survival in overall survival (OS) and progression-free survival (PFS). p16 mRNA could independently predict prognosis of OS (P = 0.0146) and PFS (P = 0.0305) in multivariate analysis. We have shown that p16 mRNA expression can act as an independent prognostic biomarker in high-grade glioma.

  6. The association between methylated CDKN2A and cervical carcinogenesis, and its diagnostic value in cervical cancer: a meta-analysis

    Directory of Open Access Journals (Sweden)

    Li J

    2016-08-01

    Full Text Available Jinyun Li,1,2,* Chongchang Zhou,1,* Haojie Zhou,3,* Tianlian Bao,1 Tengjiao Gao,1 Xiangling Jiang,1 Meng Ye1,2 1Department of Biochemistry and Molecular Biology, School of Medicine, Ningbo University, 2Department of Medical Oncology, Affiliated Hospital, Ningbo University, 3Department of Molecular Diagnosis, Ningbo Diagnostic Pathology Center, Ningbo, Zhejiang, People’s Republic of China *These authors are co-first authors of this work Background: Cervical cancer is the second deadliest gynecologic malignancy, characterized by apparently precancerous lesions and cervical intraepithelial neoplasia (CIN, and having a long course from the development of CIN to cervical cancer. Cyclin-dependent kinase inhibitor 2A (CDKN2A is a well-documented tumor suppressor gene and is commonly methylated in cervical cancer. However, the relationship between methylated CDKN2A and carcinogenesis in cervical cancer is inconsistent, and the diagnostic accuracy of methylated CDKN2A is underinvestigated. In this study, we attempted to quantify the association between CDKN2A methylation and the carcinogenesis of cervical cancer, and its diagnostic power.Methods: We systematically reviewed four electronic databases and identified 26 studies involving 1,490 cervical cancers, 1,291 CINs, and 964 controls. A pooled odds ratio (OR with corresponding 95% confidence intervals (95% CI was calculated to evaluate the association between methylated CDKN2A and the carcinogenesis of cervical cancer. Specificity, sensitivity, the area under the receiver operating characteristic curve, and the diagnostic odds ratio were computed to assess the effect of methylated CDKN2A in the diagnosis of cervical cancer.Results: Our results indicated an upward trend in the methylation frequency of CDKN2A in the carcinogenesis of cervical cancer (cancer vs control: OR =23.67, 95% CI =15.54–36.06; cancer vs CIN: OR =2.53, 95% CI =1.79–3.5; CIN vs control: OR =9.68, 95% CI =5.82–16.02. The

  7. 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...

  8. Targeting cancer stem cells with p53 modulators

    Science.gov (United States)

    Hayashi, Ryo; Appella, Ettore; Kopelovich, Levy; DeLeo, Albert B.

    2016-01-01

    Cancer stem cells (CSC) typically over-express aldehyde dehydrogenase (ALDH). Thus, ALDHbright tumor cells represent targets for developing novel cancer prevention/treatment interventions. Loss of p53 function is a common genetic event during cancer development wherein small molecular weight compounds (SMWC) that restore p53 function and reverse tumor growth have been identified. Here, we focused on two widely studied p53 SMWC, CP-31398 and PRIMA-1, to target ALDHbright CSC in human breast, endometrial and pancreas carcinoma cell lines expressing mutant or wild type (WT) p53. CP-31398 and PRIMA-1 significantly reduced CSC content and sphere formation by these cell lines in vitro. In addition, these agents were more effective in vitro against CSC compared to cisplatin and gemcitabine, two often-used chemotherapeutic agents. We also tested a combinatorial treatment in methylcholantrene (MCA)-treated mice consisting of p53 SMWC and p53-based vaccines. Yet using survival end-point analysis, no increased efficacy in the presence of either p53 SMWC alone or with vaccine compared to vaccine alone was observed. These results may be due, in part, to the presence of immune cells, such as activated lymphocytes expressing WT p53 at levels comparable to some tumor cells, wherein further increase of p53 expression by p53 SMWC may alter survival of these immune cells and negatively impact an effective immune response. Continuous exposure of mice to MCA may have also interfered with the action of these p53 SMWC, including potential direct interaction with MCA. Nonetheless, the effect of p53 SMWC on CSC and cancer treatment remains of great interest. PMID:27074569

  9. Relationship between HPV-16/18 Infection and the Alteration of p53 Gene in Transitional Cell Carcinoma of the Urinary Bladder%膀胱移行细胞癌HPV-16/18感染与p53基因改变的关系

    Institute of Scientific and Technical Information of China (English)

    郑闪; 何祖根; 肖泽均; 邸雪冰; 程书钧; 高燕宁

    2004-01-01

    目的初步探讨膀胱移行细胞癌(TCC)中HPV-16/18感染与p53基因改变的关系.方法选择已确定为HPV-16/18感染的18例膀胱TCC患者(其中HPV-16/18 E7片段阳性者13例,HPV-16/18 E7阴性者5例),采用微卫星方法检测肿瘤组织内与p53基因紧密连锁的TP53位点杂合性缺失(LOH)情况,并采用免疫组织化学方法检测p53蛋白表达情况.结果 18例TCC组织中TP53位点杂合率为83.33%(15/18),其LOH率达46.67%(7/15);p53蛋白阳性率为50.00%(9/18).其中,HPV-16/18 E7 DNA阳性和p53基因改变[包括TP53位点LOH和(或)p53蛋白阳性]并存者11例,占61.11%(11/18);仅HPV-16/18 E7 DNA阳性或p53基因改变[包括TP53位点LOH和(或)p53蛋白阳性]者5例,占27.78%(5/18);两者均阴性者2例,占11.11%(2/18).结论 HPV-16/18感染可能通过p53基因改变在TCC的发生发展过程中发挥作用,这种p53基因改变可以是LOH和(或)蛋白异常表达.

  10. p53 and its isoforms in cancer

    OpenAIRE

    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...

  11. 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

  12. Capturing the biological impact of CDKN2A and MC1R genes as an early predisposing event in melanoma and non melanoma skin cancer

    Science.gov (United States)

    Puig-Butille, Joan Anton; Escámez, María José; Garcia-Garcia, Francisco; Tell-Marti, Gemma; Fabra, Àngels; Martínez-Santamaría, Lucía; Badenas, Celia; Aguilera, Paula; Pevida, Marta; Dopazo, Joaquín; del Río, Marcela; Puig, Susana

    2014-01-01

    Germline mutations in CDKN2A and/or red hair color variants in MC1R genes are associated with an increased susceptibility to develop cutaneous melanoma or non melanoma skin cancer. We studied the impact of the CDKN2A germinal mutation p.G101W and MC1R variants on gene expression and transcription profiles associated with skin cancer. To this end we set-up primary skin cell co-cultures from siblings of melanoma prone-families that were later analyzed using the expression array approach. As a result, we found that 1535 transcripts were deregulated in CDKN2A mutated cells, with over-expression of immunity-related genes (HLA-DPB1, CLEC2B, IFI44, IFI44L, IFI27, IFIT1, IFIT2, SP110 and IFNK) and down-regulation of genes playing a role in the Notch signaling pathway. 3570 transcripts were deregulated in MC1R variant carriers. In particular, genes related to oxidative stress and DNA damage pathways were up-regulated as well as genes associated with neurodegenerative diseases such as Parkinson’s, Alzheimer and Huntington. Finally, we observed that the expression signatures indentified in phenotypically normal cells carrying CDKN2A mutations or MC1R variants are maintained in skin cancer tumors (melanoma and squamous cell carcinoma). These results indicate that transcriptome deregulation represents an early event critical for skin cancer development. PMID:24742402

  13. Telomere length and the risk of cutaneous malignant melanoma in melanoma-prone families with and without CDKN2A mutations.

    Directory of Open Access Journals (Sweden)

    Laura S Burke

    Full Text Available INTRODUCTION: Recent evidence suggests a link between constitutional telomere length (TL and cancer risk. Previous studies have suggested that longer telomeres were associated with an increased risk of melanoma and larger size and number of nevi. The goal of this study was to examine whether TL modified the risk of melanoma in melanoma-prone families with and without CDKN2A germline mutations. MATERIALS AND METHODS: We measured TL in blood DNA in 119 cutaneous malignant melanoma (CMM cases and 208 unaffected individuals. We also genotyped 13 tagging SNPs in TERT. RESULTS: We found that longer telomeres were associated with an increased risk of CMM (adjusted OR = 2.81, 95% CI = 1.02-7.72, P = 0.04. The association of longer TL with CMM risk was seen in CDKN2A- cases but not in CDKN2A+ cases. Among CMM cases, the presence of solar injury was associated with shorter telomeres (P = 0.002. One SNP in TERT, rs2735940, was significantly associated with TL (P = 0.002 after Bonferroni correction. DISCUSSION: Our findings suggest that TL regulation could be variable by CDKN2A mutation status, sun exposure, and pigmentation phenotype. Therefore, TL measurement alone may not be a good marker for predicting CMM risk.

  14. Glucose tolerance, insulin sensitivity and insulin release in European non-diabetic carriers of a polymorphism upstream of CDKN2A and CDKN2B

    DEFF Research Database (Denmark)

    Hribal, M L; Presta, I; Procopio, T

    2011-01-01

    The aim of this study was to investigate the association of the rs10811661 polymorphism near the CDKN2B/CDKN2A genes with glucose tolerance, insulin sensitivity and insulin release in three samples of white people with European ancestry....

  15. 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.

    Science.gov (United States)

    Chakraborty, Juni; Banerjee, Shuvomoy; Ray, Pallab; Hossain, Dewan Md Sakib; Bhattacharyya, Sankar; Adhikary, Arghya; Chattopadhyay, Sreya; Das, Tanya; Sa, Gaurisankar

    2010-10-22

    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 expression and p53-independent apoptosis. On the contrary, when p53 function was restored by ectopic expression, Chk-2 induced p53 accumulation that in turn overshadowed p73 activity, suggesting an antagonistic interaction between p53 family members. To understand such interaction better, p53-expressing cells were impaired differentially for p53 activity. In wild-type p53-expressing cancer cells that were silenced for p53 for several generations, p73 was activated, whereas no such trend was observed when p53 was transiently silenced. Prolonged p53 interference, even in functional p53 settings, therefore, leads to the "gain of cellular adaptation" in a way that alters the cellular microenvironment in favor of p73 activation by altering p73-regulatory proteins, e.g. Chk1 activation and dominant negative p73 down-regulation. These findings not only unveil a hitherto unexplained mechanism underlying the functional switchover from p53 to p73, but also validate p73 as a promising and potential target for cancer therapy in the absence of functional p53.

  16. 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.

  17. 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

    2014-12-05

    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.

  18. MicroRNA Control of p53.

    Science.gov (United States)

    Liu, Juan; Zhang, Cen; Zhao, Yuhan; Feng, Zhaohui

    2017-01-01

    Tumor suppressor p53 plays a central role in tumor suppression. As a transcription factor, p53 mainly exerts its tumor suppressive function through transcriptional regulation of many target genes. To maintain the proper function of p53, p53 protein level and activity are exquisitely controlled by a group of positive and negative regulators in cells. Thus, p53, its regulators, and regulated genes form a complicated p53 signaling network. microRNAs (miRNAs) are a group of endogenous small non-coding RNA molecules. miRNAs play an important role in regulation of gene expression by blocking translational protein synthesis and/or degrading target mRNAs. Recent studies have demonstrated that p53 and its network are regulated by miRNAs at multiple levels. Some miRNAs regulate the level and function of p53 through directly targeting p53, whereas some other miRNAs target regulators of p53, such as MDM2 and MDM4, to indirectly regulate the activity and function of p53. On the other hand, p53 also regulates the transcriptional expression and the biogenesis of a group of miRNAs, which contributes to the tumor suppressive function of p53. p53 is the most frequently mutated gene in human cancer. Many tumor-associated mutant p53, which have "gain-of-function" activities in tumorigenesis independently of wild type p53, can regulate the expression of different miRNAs and modulate the biogenesis of specific miRNAs to promote tumorigenesis. These findings have demonstrated that miRNAs are important regulators and mediators of p53 and its signaling pathway, which highlights a pivotal role of miRNAs in the p53 network and cancer. J. Cell. Biochem. 118: 7-14, 2017. © 2016 Wiley Periodicals, Inc.

  19. Comparison study of MS-HRM and pyrosequencing techniques for quantification of APC and CDKN2A gene methylation.

    Directory of Open Access Journals (Sweden)

    Francesca Migheli

    Full Text Available 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.

  20. 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.

  1. 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.

  2. Biallelic ATM alterations detected at diagnosis identify a subset of treatment-naïve chronic lymphocytic leukemia patients with reduced overall survival similar to patients with p53 deletion.

    Science.gov (United States)

    Lozano-Santos, Carol; García-Vela, José A; Pérez-Sanz, Nuria; Nova-Gurumeta, Sara; Fernandez-Cuevas, Belen; Gomez-Lozano, Natalia; Sánchez-Beato, Margarita; Sanchez-Godoy, Pedro; Bueno, José Luis; Garcia-Marco, José A

    2017-04-01

    The prognostic impact of biallelic ATM abnormalities (ATM mutation and concurrent 11q deletion) remains unknown. We studied ATM, BIRC3, SF3B1, and NOTCH1 genes in 118 treatment-naïve CLL patients at diagnosis. Patients with biallelic ATM alteration had a similar time to first treatment (TTFT) and shorter overall survival (OS) compared with patients with isolated 11q deletion and shorter TTFT and OS when compared to patients with wild-type ATM. Furthermore, biallelic ATM alteration (HR: 6.4; p ≤ 0.007) was significantly associated with an increased risk of death similar to p53 deletion (HR: 6.1; p ≤ 0.004), superior to 11q deletion alone (HR: 2.8; p ≤ 0.022) and independent of other significant parameters such as age, advanced clinical stage, and complex karyotype. Our results suggest the identification of ATM mutations in CLL patients with 11q deletion at diagnosis is clinically relevant and predicts disease progression, poor response to the treatment, and reduced OS independent of other molecular prognostic factors.

  3. p53 Acetylation: Regulation and Consequences

    OpenAIRE

    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...

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

    OpenAIRE

    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...

  5. Gene p53 mutations, protein p53, and anti-p53 antibodies as biomarkers of cancer process.

    Science.gov (United States)

    Lutz, Waldemar; Nowakowska-Swirta, Ewa

    2002-01-01

    The finding that gene mutations and changes in their expression form the basis of cancer processes, has prompted molecular epidemiologists to use biomarkers for detecting damaged genes or proteins synthesized under their control in easily available cellular material or systemic liquids. Mutations in the suppressor gen p53 are thought to be essential for cancer development. This gen is one of the most important regulators of transcription, cellular cycle, DNA repair and apoptosis detected till now. Inactivation of gene p53 leads to uncontrolled cell divisions, and further to transformation of normal cells into the carcinous ones. Observations that mutations in gene p53 appear under conditions of occupational and environmental exposures to chemical and physical carcinogens, such as vinyl chloride, radon, or aflatoxin B1, have proved to be of enormous importance for the occupational and environmental health. Changes in expression of gene p53, and also its mutations, cause variations of cellular protein p53 concentration. Higher cellular protein p53 levels are associated with increased protein transfer to the extracellular liquid and to blood. It has been observed that increased blood serum protein p53 concentrations may have a prognostic value in early diagnosis of lung cancer. The results of a number of studies confirm that accumulation of a mutated form of protein p53, and presumably also large quantities of wild forms of that protein in the cells, may be a factor that triggers the production of anti-p53 antibodies. Statistical analysis showed that anti-p53 antibodies can be regarded as a specific biomarker of cancer process. The prevalence of anti-p53 antibodies correlated with the degree of cancer malignancy. The increased incidence of anti-p53 antibodies was also associated with higher frequency of mutations in gene p53. There are some reports confirming that anti-p53 antibodies emerging in blood serum in the subclinical phase of cancer development may be

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

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Suzanne M. [Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States)], E-mail: suzanne.morris@fda.hhs.gov; Akerman, Gregory S. [Toxicology Branch, Health Effects Division (7509P), US Environmental Protection Agency, 1200 Pennsylvania Avenue, NW, Washington, DC 20460 (United States); Desai, Varsha G. [Division of Systems Toxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States); Tsai, Chen-an [Biostatistics Center and Department of Public Health, China Medical University, Taichung, 40402, Taiwan (China); Tolleson, William H.; Melchior, William B. [Division of Biochemical Toxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States); Lin, Chien-Ju [Division of Personalized Nutrition and Medicine, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States); Fuscoe, James C. [Division of Systems Toxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States); Casciano, Daniel A. [Dan Casciano and Associates, 47 Marcella Drive, Little Rock, AR 72233 (United States); Chen, James J. [Division of Personalized Nutrition and Medicine, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States)

    2008-04-02

    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{sup -/-} and p53{sup +/-} mice. Six male mice from each genotype (p53{sup +/+}, p53{sup +/-}, and p53{sup -/-}) 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{sup +/+} and p53{sup +/-} or between p53{sup +/+} and p53{sup -/-} at the level of p {<=} 0.05. Both genes with increased expression and decreased expression were identified in p53{sup +/-} and in p53{sup -/-} mice. Most notable in the gene list derived from the p53{sup +/-} mice was the significant reduction in p53 mRNA. In the p53{sup -/-} 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.

  7. Metabolic regulation by p53 family members.

    Science.gov (United States)

    Berkers, Celia R; Maddocks, Oliver D K; Cheung, Eric C; Mor, Inbal; Vousden, Karen H

    2013-11-05

    The function of p53 is best understood in response to genotoxic stress, but increasing evidence suggests that p53 also plays a key role in the regulation of metabolic homeostasis. p53 and its family members directly influence various metabolic pathways, enabling cells to respond to metabolic stress. These functions are likely to be important for restraining the development of cancer but could also have a profound effect on the development of metabolic diseases, including diabetes. A better understanding of the metabolic functions of p53 family members may aid in the identification of therapeutic targets and reveal novel uses for p53-modulating drugs.

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

    Directory of Open Access Journals (Sweden)

    Zorka Milićević

    2014-01-01

    Full Text Available 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 intriguing findings is that mutant p53 appears as discrete dot-shaped regions within the nucleus of breast cancer cells. In many malignant cells, the nucleolar sequestration of p53 is evident. These observations support the view that the nucleolus is involved directly in the mediation of p53 function or indirectly by the control of the localization of p53 interplayers. p53 expressed in the nuclear fraction of breast cancer cells revealed a wide spectrum of isoforms. p53 isoforms ΔNp53 (47 kDa and Δ133p53β (35 kDa, known as dominant-negative repressors of p53 function, were detected as the most predominant variants in nuclei of invasive breast carcinoma cells. The isoforms expressed also varied between individual tumors, indicating potential roles of these p53 variants in human breast cancer.

  9. Normal repair of ultraviolet radiation-induced DNA damage in familial melanoma without CDKN2A or CDK4 gene mutation.

    Science.gov (United States)

    Shannon, J A; Matias, C; Luxford, C; Kefford, R F; Mann, G J

    1999-04-01

    Excessive sun exposure and family history are strong risk factors for the development of cutaneous melanoma. Inherited susceptibility to this type of skin cancer could therefore result from constitutively impaired capacity to repair ultraviolet (UV)-induced DNA lesions. While a proportion of familial melanoma kindreds exhibit germline mutations in the cell cycle regulatory gene CDKN2A (p16INK4a) or its protein target, cyclin-dependent kinase 4 (CDK4), the biochemical basis of most familial melanoma is unknown. We have examined lymphoblastoid cell lines from melanoma-affected and unaffected individuals from large hereditary melanoma kindreds which are not attributable to CDKN2A or CDK4 gene mutation. These lines were tested for sensitivity of clonogenic growth to UV radiation and for their ability to repair transfected UV-damaged plasmid templates (host cell reactivation). Two of seven affected-unaffected pairs differed in colony survival after exposure to UVB radiation; however, no significant differences were observed in the host-cell reactivation assays. These results indicate that melanoma susceptibility genes other than CDKN2A and CDK4 do not impair net capacity to repair UV-induced DNA damage.

  10. p53 regulates the cardiac transcriptome

    Science.gov (United States)

    Mak, Tak W.; Hauck, Ludger; Grothe, Daniela; Billia, Filio

    2017-01-01

    The tumor suppressor Trp53 (p53) inhibits cell growth after acute stress by regulating gene transcription. The mammalian genome contains hundreds of p53-binding sites. However, whether p53 participates in the regulation of cardiac tissue homeostasis under normal conditions is not known. To examine the physiologic role of p53 in adult cardiomyocytes in vivo, Cre-loxP–mediated conditional gene targeting in adult mice was used. Genome-wide transcriptome analyses of conditional heart-specific p53 knockout mice were performed. Genome-wide annotation and pathway analyses of >5,000 differentially expressed transcripts identified many p53-regulated gene clusters. Correlative analyses identified >20 gene sets containing more than 1,000 genes relevant to cardiac architecture and function. These transcriptomic changes orchestrate cardiac architecture, excitation-contraction coupling, mitochondrial biogenesis, and oxidative phosphorylation capacity. Interestingly, the gene expression signature in p53-deficient hearts confers resistance to acute biomechanical stress. The data presented here demonstrate a role for p53, a previously unrecognized master regulator of the cardiac transcriptome. The complex contributions of p53 define a biological paradigm for the p53 regulator network in the heart under physiological conditions. PMID:28193895

  11. Regulation of autophagy by cytoplasmic p53.

    Science.gov (United States)

    Tasdemir, Ezgi; Maiuri, M Chiara; Galluzzi, Lorenzo; Vitale, Ilio; Djavaheri-Mergny, Mojgan; D'Amelio, Marcello; Criollo, Alfredo; Morselli, Eugenia; Zhu, Changlian; Harper, Francis; Nannmark, Ulf; Samara, Chrysanthi; Pinton, Paolo; Vicencio, José Miguel; Carnuccio, Rosa; Moll, Ute M; Madeo, Frank; Paterlini-Brechot, Patrizia; Rizzuto, Rosario; Szabadkai, Gyorgy; Pierron, Gérard; Blomgren, Klas; Tavernarakis, Nektarios; Codogno, Patrice; Cecconi, Francesco; Kroemer, Guido

    2008-06-01

    Multiple cellular stressors, including activation of the tumour suppressor p53, can stimulate autophagy. Here we show that deletion, depletion or inhibition of p53 can induce autophagy in human, mouse and nematode cells subjected to knockout, knockdown or pharmacological inhibition of p53. Enhanced autophagy improved the survival of p53-deficient cancer cells under conditions of hypoxia and nutrient depletion, allowing them to maintain high ATP levels. Inhibition of p53 led to autophagy in enucleated cells, and cytoplasmic, not nuclear, p53 was able to repress the enhanced autophagy of p53(-/-) cells. Many different inducers of autophagy (for example, starvation, rapamycin and toxins affecting the endoplasmic reticulum) stimulated proteasome-mediated degradation of p53 through a pathway relying on the E3 ubiquitin ligase HDM2. Inhibition of p53 degradation prevented the activation of autophagy in several cell lines, in response to several distinct stimuli. These results provide evidence of a key signalling pathway that links autophagy to the cancer-associated dysregulation of p53.

  12. p53 and MDM2 protein expression in actinic cheilitis.

    Science.gov (United States)

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

    2008-01-01

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

  13. p53 and MDM2 protein expression in actinic cheilitis

    Directory of Open Access Journals (Sweden)

    Maria da Conceição Andrade de Freitas

    2008-12-01

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

  14. 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.

  15. 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.

  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. Structure of the E6/E6AP/p53 complex required for HPV-mediated degradation of p53

    Science.gov (United States)

    Martinez-Zapien, Denise; Ruiz, Francesc Xavier; Poirson, Juline; Mitschler, André; Ramirez-Ramos, Juan; Forster, Anne; Cousido-Siah, Alexandra; Masson, Murielle; Pol, Scott Vande; Podjarny, Alberto; Travé, Gilles; Zanier, Katia

    2015-01-01

    Summary The p53 pro-apoptotic tumor suppressor is mutated or functionally altered in most cancers. In epithelial tumors induced by “high-risk” mucosal Human Papillomaviruses (hrm-HPVs), including human cervical carcinoma and a growing number of head-and-neck cancers 1, p53 is degraded by the viral oncoprotein E6 2. In this process, E6 binds to a short LxxLL consensus sequence within the cellular ubiquitin ligase E6AP 3. Subsequently, the E6/E6AP heterodimer recruits and degrades p53 4. Neither E6 nor E6AP are separately able to recruit p53 3,5, and the precise mode of assembly of E6, E6AP and p53 is unknown. Here, we solved the crystal structure of a ternary complex comprising full-length HPV16 E6, the LxxLL motif of E6AP and the core domain of p53. The LxxLL motif of E6AP renders the conformation of E6 competent for interaction with p53 by structuring a p53-binding cleft on E6. Mutagenesis of critical positions at the E6-p53 interface disrupts p53 degradation. The E6-binding site of p53 is distal from previously described DNA- and protein-binding surfaces of the core domain. This suggests that, in principle, E6 may avoid competition with cellular factors by targeting both free and bound p53 molecules. The E6/E6AP/p53 complex represents a prototype of viral hijacking of both the ubiquitin-mediated protein degradation pathway and the p53 tumor suppressor pathway. The present structure provides a framework for the design of inhibitory therapeutic strategies against HPV-mediated oncogenesis. PMID:26789255

  18. 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.

  19. 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 o...

  20. SUMOylation of p53 mediates interferon activities

    Science.gov (United States)

    Marcos-Villar, Laura; Pérez-Girón, José V; Vilas, Jéssica M; Soto, Atenea; de la Cruz-Hererra, Carlos F; Lang, Valerie; Collado, Manuel; Vidal, Anxo; Rodríguez, Manuel S; Muñoz-Fontela, César; Rivas, Carmen

    2013-01-01

    There is growing evidence that many host proteins involved in innate and intrinsic immunity are regulated by SUMOylation, and that SUMO contributes to the regulatory process that governs the initiation of the type I interferon (IFN) response. The tumor suppressor p53 is a modulator of the IFN response that plays a role in virus-induced apoptosis and in IFN-induced senescence. Here we demonstrate that IFN treatment increases the levels of SUMOylated p53 and induces cellular senescence through a process that is partially dependent upon SUMOylation of p53. Similarly, we show that vesicular stomatitis virus (VSV) infection induces p53 SUMOylation, and that this modification favors the control of VSV replication. Thus, our study provides evidence that IFN signaling induces p53 SUMOylation, which results in the activation of a cellular senescence program and contributes to the antiviral functions of interferon. PMID:23966171

  1. Modeling the Etiology of p53-mutated Cancer Cells.

    Science.gov (United States)

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

    2016-05-06

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

  2. p53 oligomerization status modulates cell fate decisions between growth, arrest and apoptosis.

    Science.gov (United States)

    Fischer, Nicholas W; Prodeus, Aaron; Malkin, David; Gariépy, Jean

    2016-12-01

    Mutations in the oligomerization domain of p53 are genetically linked to cancer susceptibility in Li-Fraumeni Syndrome. These mutations typically alter the oligomeric state of p53 and impair its transcriptional activity. Activation of p53 through tetramerization is required for its tumor suppressive function by inducing transcriptional programs that lead to cell fate decisions such as cell cycle arrest or apoptosis. How p53 chooses between these cell fate outcomes remains unclear. Here, we use 5 oligomeric variants of p53, including 2 novel p53 constructs, that yield either monomeric, dimeric or tetrameric forms of p53 and demonstrate that they induce distinct cellular activities and gene expression profiles that lead to different cell fate outcomes. We report that dimeric p53 variants are cytostatic and can arrest cell growth, but lack the ability to trigger apoptosis in p53-null cells. In contrast, p53 tetramers induce rapid apoptosis and cell growth arrest, while a monomeric variant is functionally inactive, supporting cell growth. In particular, the expression of pro-arrest CDKN1A and pro-apoptotic P53AIP1 genes are important cell fate determinants that are differentially regulated by the oligomeric state of p53. This study suggests that the most abundant oligomeric species of p53 present in resting cells, namely p53 dimers, neither promote cell growth or cell death and that shifting the oligomeric state equilibrium of p53 in cells toward monomers or tetramers is a key parameter in p53-based cell fate decisions.

  3. Clinical and pathological correlations of marrow PUMA and P53 expressions in myelodysplastic syndromes.

    Science.gov (United States)

    Bektas, Ozlen; Uner, Aysegul; Buyukasik, Yahya; Uz, Burak; Bozkurt, Sureyya; Eliacik, Eylem; Işik, Ayse; Haznedaroglu, Ibrahim Celalettin; Goker, Hakan; Demiroglu, Haluk; Aksu, Salih; Ozcebe, Osman Ilhami; Sayinalp, Nilgun

    2015-05-01

    p53 is a key regulator of apoptosis. p53 upregulated modulator of apoptosis (PUMA) is a critical mediator of p53-dependent and independent apoptosis. The objective of this study was to evaluate the relationship of p53 and PUMA to the prognosis of MDS. Bone marrow biopsies of MDS patients at the time of diagnosis (n = 76) and at the time of transformation (n = 19) were included in the study group. The expression of p53 and PUMA was evaluated using immunohistochemistry. When compared to the control group, both p53 (p PUMA (p = 0.012) expression levels were significantly higher in MDS group. In MDS group, there was a moderate positive correlation between p53 and PUMA expressions. PUMA expression was not correlated with event free and overall survival. However, overall survival was significantly lower in cases with p53 expression in more than 50% of the cells. There was an increase in PUMA expression in cases that showed transformation as compared to the initial diagnostic bone marrows but was not statistically significant. The correlation that existed between p53 and PUMA was lost in transformed cases. Our results showed that PUMA and p53 expressions are increased in MDS marrows compared to normal marrows. PUMA expression increases further during transformation while the expression of p53 is not significantly altered which suggests that PUMA alterations might be a late event during the evolution of MDS.

  4. 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.

  5. p53 in the game of transposons.

    Science.gov (United States)

    Wylie, Annika; Jones, Amanda E; Abrams, John M

    2016-11-01

    Throughout the animal kingdom, p53 genes function to restrain mobile elements and recent observations indicate that transposons become derepressed in human cancers. Together, these emerging lines of evidence suggest that cancers driven by p53 mutations could represent "transpospoathies," i.e. disease states linked to eruptions of mobile elements. The transposopathy hypothesis predicts that p53 acts through conserved mechanisms to contain transposon movement, and in this way, prevents tumor formation. How transposon eruptions provoke neoplasias is not well understood but, from a broader perspective, this hypothesis also provides an attractive framework to explore unrestrained mobile elements as inciters of late-onset idiopathic disease. Also see the video abstract here.

  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.

    Science.gov (United States)

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

    2013-01-15

    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 LSD1 on these proteins is necessary for their stabilization. To examine the role of LSD1 we generated LSD1 heterozygous (LSD1+/-) and homozygous (LSD1-/-) knockouts in the human colorectal cancer cell line HCT116. The deletion of LSD1 led to a reduced cell proliferation both in vitro and in vivo. Surprisingly, the knockout of LSD1 in HCT116 cells did not result in global increases in its histone substrate H3K4me2 (dimethyl-H3K4) or changes in the stability or function of p53 or DNMT1. However, there was a significant difference in gene expression between cells containing LSD1 and those null for LSD1. The results of the present study suggested that LSD1 is critical in the regulation of cell proliferation, but also indicated that LSD1 is not an absolute requirement for the stabilization of either p53 or DNMT1.

  7. Differential Expression of ADAM23, CDKN2A (P16), MMP14 and VIM Associated with Giant Cell Tumor of Bone.

    Science.gov (United States)

    Conceição, André Luis Giacometti; Babeto, Erica; Candido, Natalia Maria; Franco, Fernanda Craveiro; de Campos Zuccari, Débora Aparecida Pires; Bonilha, Jane Lopes; Cordeiro, José Antônio; Calmon, Marilia Freitas; Rahal, Paula

    2015-01-01

    Though benign, giant cell tumor of bone (GCTB) can become aggressive and can exhibit a high mitotic rate, necrosis and rarely vascular invasion and metastasis. GCTB has unique histologic characteristics, a high rate of multinucleated cells, a variable and unpredictable growth potential and uncertain biological behavior. In this study, we sought to identify genes differentially expressed in GCTB, thus building a molecular profile of this tumor. We performed quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry and analyses of methylation to identify genes that are putatively associated with GCTB. The expression of the ADAM23 and CDKN2A genes was decreased in GCTB samples compared to normal bone tissue, measured by qPCR. Additionally, a high hypermethylation frequency of the promoter regions of ADAM23 and CDKN2A in GCTB was observed. The expression of the MAP2K3, MMP14, TIMP2 and VIM genes was significantly higher in GCTB than in normal bone tissue, a fact that was confirmed by qPCR and immunohistochemistry. The set of genes identified here furthers our understanding of the molecular basis of GCTB.

  8. Transcriptomic Analysis of the Claudin Interactome in Malignant Pleural Mesothelioma: Evaluation of the Effect of Disease Phenotype, Asbestos Exposure, and CDKN2A Deletion Status

    Science.gov (United States)

    Rouka, Erasmia; Vavougios, Georgios D.; Solenov, Evgeniy I.; Gourgoulianis, Konstantinos I.; Hatzoglou, Chrissi; Zarogiannis, Sotirios G.

    2017-01-01

    Malignant pleural mesothelioma (MPM) is a highly aggressive tumor primarily associated with asbestos exposure. Early detection of MPM is restricted by the long latency period until clinical presentation, the ineffectiveness of imaging techniques in early stage detection and the lack of non-invasive biomarkers with high sensitivity and specificity. In this study we used transcriptome data mining in order to determine which CLAUDIN (CLDN) genes are differentially expressed in MPM as compared to controls. Using the same approach we identified the interactome of the differentially expressed CLDN genes and assessed their expression profile. Subsequently, we evaluated the effect of tumor histology, asbestos exposure, CDKN2A deletion status, and gender on the gene expression level of the claudin interactome. We found that 5 out of 15 studied CLDNs (4, 5, 8, 10, 15) and 4 out of 27 available interactors (S100B, SHBG, CDH5, CXCL8) were differentially expressed in MPM specimens vs. healthy tissues. The genes encoding the CLDN-15 and S100B proteins present differences in their expression profile between the three histological subtypes of MPM. Moreover, CLDN-15 is significantly under-expressed in the cohort of patients with previous history of asbestos exposure. CLDN-15 was also found significantly underexpressed in patients lacking the CDKN2A gene. These results warrant the detailed in vitro investigation of the role of CDLN-15 in the pathobiology of MPM. PMID:28377727

  9. 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; Dusek, Rachel L.; 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-...

  10. Mdm2 RING mutation enhances p53 transcriptional activity and p53-p300 interaction.

    Directory of Open Access Journals (Sweden)

    Hilary V Clegg

    Full Text Available The p53 transcription factor and tumor suppressor is regulated primarily by the E3 ubiquitin ligase Mdm2, which ubiquitinates p53 to target it for proteasomal degradation. Aside from its ubiquitin ligase function, Mdm2 has been believed to be capable of suppressing p53's transcriptional activity by binding with and masking the transactivation domain of p53. The ability of Mdm2 to restrain p53 activity by binding alone, without ubiquitination, was challenged by a 2007 study using a knockin mouse harboring a single cysteine-to-alanine point mutation (C462A in Mdm2's RING domain. Mouse embryonic fibroblasts with this mutation, which abrogates Mdm2's E3 ubiquitin ligase activity without affecting its ability to bind with p53, were unable to suppress p53 activity. In this study, we utilized the Mdm2(C462A mouse model to characterize in further detail the role of Mdm2's RING domain in the control of p53. Here, we show in vivo that the Mdm2(C462A protein not only fails to suppress p53, but compared to the complete absence of Mdm2, Mdm2(C462A actually enhances p53 transcriptional activity toward p53 target genes p21/CDKN1A, MDM2, BAX, NOXA, and 14-3-3σ. In addition, we found that Mdm2(C462A facilitates the interaction between p53 and the acetyltransferase CBP/p300, and it fails to heterodimerize with its homolog and sister regulator of p53, Mdmx, suggesting that a fully intact RING domain is required for Mdm2's inhibition of the p300-p53 interaction and for its interaction with Mdmx. These findings help us to better understand the complex regulation of the Mdm2-p53 pathway and have important implications for chemotherapeutic agents targeting Mdm2, as they suggest that inhibition of Mdm2's E3 ubiquitin ligase activity may be sufficient for increasing p53 activity in vivo, without the need to block Mdm2-p53 binding.

  11. p53 gene therapy using RNA interference.

    Science.gov (United States)

    Berindan-Neagoe, I; Balacescu, O; Burz, C; Braicu, C; Balacescu, L; Tudoran, O; Cristea, V; Irimie, A

    2009-09-01

    p53 gene, discovered almost 35 years ago, keeps the main role in cell cycle control, apoptosis pathways and transcription. p53 gene is found mutated in more than 50% of all human cancers in different locations. Many structures from viral to non viral were designed to incorporate and deliver in appropriate conditions forms of p53 gene or its transcripts, systemically to target tumor cells and to eliminate them through apoptosis or to restore the normal tumor suppressor gene role. Each delivery system presents advantages and low performance in relation to immune system recognition and acceptance. One of the major discoveries in the last years, silencing of RNA, represents a powerful tool for inhibiting post transcriptional control of gene expression. According to several studies, the RNA silencing technology for p53 transcripts together with other carriers or transporters at nano level can be used for creating new therapeutic models. RNA interference for p53 uses different double-stranded (ds) molecules like short interfering (si) RNA and, despite the difficulty of introducing them into mammalian cells due to immune system response, it can be exploited in cancer therapy.

  12. 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

  13. Emerging Non-Canonical Functions and Regulation by p53: p53 and Stemness.

    Science.gov (United States)

    Olivos, David J; Mayo, Lindsey D

    2016-11-26

    Since its discovery nearly 40 years ago, p53 has ascended to the forefront of investigated genes and proteins across diverse research disciplines and is recognized most exclusively for its role in cancer as a tumor suppressor. Levine and Oren (2009) reviewed the evolution of p53 detailing the significant discoveries of each decade since its first report in 1979. In this review, we will highlight the emerging non-canonical functions and regulation of p53 in stem cells. We will focus on general themes shared among p53's functions in non-malignant stem cells and cancer stem-like cells (CSCs) and the influence of p53 on the microenvironment and CSC niche. We will also examine p53 gain of function (GOF) roles in stemness. Mutant p53 (mutp53) GOFs that lead to survival, drug resistance and colonization are reviewed in the context of the acquisition of advantageous transformation processes, such as differentiation and dedifferentiation, epithelial-to-mesenchymal transition (EMT) and stem cell senescence and quiescence. Finally, we will conclude with therapeutic strategies that restore wild-type p53 (wtp53) function in cancer and CSCs, including RING finger E3 ligases and CSC maintenance. The mechanisms by which wtp53 and mutp53 influence stemness in non-malignant stem cells and CSCs or tumor-initiating cells (TICs) are poorly understood thus far. Further elucidation of p53's effects on stemness could lead to novel therapeutic strategies in cancer research.

  14. Distinct p53, p53:LANA, and LANA Complexes in Kaposi's Sarcoma-Associated Herpesvirus Lymphomas▿

    OpenAIRE

    Chen, Wuguo; Hilton, Isaac B.; Staudt, Michelle R; Burd, Christin E.; Dittmer, Dirk P

    2010-01-01

    The role of p53 in primary effusion lymphoma (PEL) is complicated. The latency-associated nuclear antigen (LANA) of Kaposi's sarcoma-associated herpesvirus (KSHV) binds p53. Despite this interaction, we had found that p53 was functional in PEL, i.e., able to induce apoptosis in response to DNA damage (C. E. Petre, S. H. Sin, and D. P. Dittmer, J. Virol. 81:1912-1922, 2007), and that hdm2 was overexpressed. To further elucidate the relationship between LANA, p53, and hdm2, we purified LANA com...

  15. p53 suppresses tetraploid development in mice.

    Science.gov (United States)

    Horii, Takuro; Yamamoto, Masamichi; Morita, Sumiyo; Kimura, Mika; Nagao, Yasumitsu; Hatada, Izuho

    2015-03-10

    Mammalian tetraploid embryos die in early development because of defects in the epiblast. Experiments with diploid/tetraploid chimeric mice, obtained via the aggregation of embryonic stem cells, clarified that while tetraploid cells are excluded from epiblast derivatives, diploid embryos with tetraploid extraembryonic tissues can develop to term. Today, this method, known as tetraploid complementation, is usually used for rescuing extraembryonic defects or for obtaining completely embryonic stem (ES) cell-derived pups. However, it is still unknown why defects occur in the epiblast during mammalian development. Here, we demonstrated that downregulation of p53, a tumour suppressor protein, rescued tetraploid development in the mammalian epiblast. Tetraploidy in differentiating epiblast cells triggered p53-dependent cell-cycle arrest and apoptosis, suggesting the activation of a tetraploidy checkpoint during early development. Finally, we found that p53 downregulation rescued tetraploid embryos later in gestation.

  16. Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment

    Directory of Open Access Journals (Sweden)

    Yan Cui

    2016-11-01

    Full Text Available The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME. It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome.

  17. Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment

    Science.gov (United States)

    Cui, Yan; Guo, Gang

    2016-01-01

    The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME). It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome. PMID:27869779

  18. Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment.

    Science.gov (United States)

    Cui, Yan; Guo, Gang

    2016-11-19

    The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME). It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome.

  19. 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.

  20. 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.

  1. 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.

  2. Molecular Mechanisms of p53 Deregulation in Cancer: An Overview in Multiple Myeloma.

    Science.gov (United States)

    Herrero, Ana B; Rojas, Elizabeta A; Misiewicz-Krzeminska, Irena; Krzeminski, Patryk; Gutiérrez, Norma C

    2016-11-30

    The p53 pathway is inactivated in the majority of human cancers. Although this perturbation frequently occurs through the mutation or deletion of p53 itself, there are other mechanisms that can attenuate the pathway and contribute to tumorigenesis. For example, overexpression of important p53 negative regulators, such as murine double minute 2 (MDM2) or murine double minute 4 (MDM4), epigenetic deregulation, or even alterations in TP53 mRNA splicing. In this work, we will review the different mechanisms of p53 pathway inhibition in cancer with special focus on multiple myeloma (MM), the second most common hematological malignancy, with low incidence of p53 mutations/deletions but growing evidence of indirect p53 pathway deregulation. Translational implications for MM and cancer prognosis and treatment are also reviewed.

  3. 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.

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

    OpenAIRE

    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 p5...

  5. 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.

  6. The Increased Level of Serum p53 in Hepatitis B-Associated Liver Cirrhosis

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    Parisa Shahnazari

    2014-09-01

    Full Text Available Background: The ability of tumour suppressor protein p53 (P53 to regulate cell cycle processes can be modulated by hepatitis B virus (HBV. While preliminary evidences indicates the involvement of protein-x of HBV (HBx in altering p53 DNA binding, no further data have been accumulated for the significance of serum p53 in chronic hepatitis B virus infected patients. Methods: 72 non-cirrhotic and 19 cirrhotic patients infected by HBV were enrolled for the analysis in this study. Enzyme linked immunosorbent assay (ELISA was performed to study the concentrations of serum p53 protein. The tertiary structures of HBx and P53 were docked by Z-dock and Hex servers for in-silico protein-protein interaction analysis. Results: There was a significant association between the serum p53 and cirrhosis (OR=1.81 95% CI: 1.017-3.2, P=0.044. Cirrhotic patients had higher level of serum p53 compare with chronic infection of HBV (1.98±1.22 vs. 1.29±0.72 U/ml, P=0.05. No evidence of correlation was seen between the different variables such as age, gender, log viral load, serum alkaline phosphatase (ALP and alanine aminotransferase (ALT with serum p53. Tertiary model shows that the amino acid residues from Arg110 to Lys132 of the N-terminal of P53 which is critical for ubiquitination, are bonded to a region in N- terminal of HBx amino acid residues from Arg19 to Ser33. Conclusion: There is an increase in serum p53 in HBV-related cirrhosis patients. In this case, HBx might be responsible for such higher concentration of p53 through HBx-p53 protein-protein interaction, as is shown by molecular modeling approach.

  7. 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.

  8. Smooth muscle hyperplasia due to loss of smooth muscle α-actin is driven by activation of focal adhesion kinase, altered p53 localization and increased levels of platelet-derived growth factor receptor-β.

    Science.gov (United States)

    Papke, Christina L; Cao, Jiumei; Kwartler, Callie S; Villamizar, Carlos; Byanova, Katerina L; Lim, Soon-Mi; Sreenivasappa, Harini; Fischer, Grant; Pham, John; Rees, Meredith; Wang, Miranda; Chaponnier, Christine; Gabbiani, Giulio; Khakoo, Aarif Y; Chandra, Joya; Trache, Andreea; Zimmer, Warren; Milewicz, Dianna M

    2013-08-01

    Mutations in ACTA2, encoding the smooth muscle cell (SMC)-specific isoform of α-actin (α-SMA), cause thoracic aortic aneurysms and dissections and occlusive vascular diseases, including early onset coronary artery disease and stroke. We have shown that occlusive arterial lesions in patients with heterozygous ACTA2 missense mutations show increased numbers of medial or neointimal SMCs. The contribution of SMC hyperplasia to these vascular diseases and the pathways responsible for linking disruption of α-SMA filaments to hyperplasia are unknown. Here, we show that the loss of Acta2 in mice recapitulates the SMC hyperplasia observed in ACTA2 mutant SMCs and determine the cellular pathways responsible for SMC hyperplasia. Acta2(-/-) mice showed increased neointimal formation following vascular injury in vivo, and SMCs explanted from these mice demonstrated increased proliferation and migration. Loss of α-SMA induced hyperplasia through focal adhesion (FA) rearrangement, FA kinase activation, re-localization of p53 from the nucleus to the cytoplasm and increased expression and ligand-independent activation of platelet-derived growth factor receptor beta (Pdgfr-β). Disruption of α-SMA in wild-type SMCs also induced similar cellular changes. Imatinib mesylate inhibited Pdgfr-β activation and Acta2(-/-) SMC proliferation in vitro and neointimal formation with vascular injury in vivo. Loss of α-SMA leads to SMC hyperplasia in vivo and in vitro through a mechanism involving FAK, p53 and Pdgfr-β, supporting the hypothesis that SMC hyperplasia contributes to occlusive lesions in patients with ACTA2 missense mutations.

  9. Diabetes susceptibility in Mayas: Evidence for the involvement of polymorphisms in HHEX, HNF4α, KCNJ11, PPARγ, CDKN2A/2B, SLC30A8, CDC123/CAMK1D, TCF7L2, ABCA1 and SLC16A11 genes.

    Science.gov (United States)

    Lara-Riegos, J C; Ortiz-López, M G; Peña-Espinoza, B I; Montúfar-Robles, I; Peña-Rico, M A; Sánchez-Pozos, K; Granados-Silvestre, M A; Menjivar, M

    2015-07-01

    Association of type 2 diabetes (T2D) with common variants in HHEX, HNF4α, KCNJ11, PPARγ, CDKN2A/2B, SLC30A8, CDC123/CAMK1D, TCF7L2, ABCA1 and SLC16A11 genes have been reported, mainly in populations of European and Asian ancestry and to a lesser extent in Latin Americans. Thus, we aimed to investigate the contribution of rs1111875 (HHEX), rs1800961 (HNF4α), rs5219 (KCNJ11), rs1801282 (PPARγ), rs10811661 (CDKN2A/2B), rs13266634 (SLC30A8), rs12779790 (CDC123/CAMK1D), rs7903146 (TCF7L2), rs9282541 (ABCA1) and rs13342692 (SLC16A11) polymorphisms in the genetic background of Maya population to associate their susceptibility to develop T2D. This is one of the first studies designed specifically to investigate the inherited component of T2D in the indigenous population of Mexico. SNPs were genotyped by allelic discrimination method in 575 unrelated Maya individuals. Two SNPs rs10811661 and rs928254 were significantly associated with T2D after adjusting for BMI; rs10811661 in a recessive and rs9282541 in a dominant model. Additionally, we found phenotypical alterations associated with genetic variants: HDL to rs9282541 and insulin to rs13342692. In conclusion, these findings support an association of genetic polymorphisms to develop T2D in Maya population.

  10. INGN 201: Ad-p53, Ad5CMV-p53, Adenoviral p53, INGN 101, p53 gene therapy--Introgen, RPR/INGN 201.

    Science.gov (United States)

    2003-01-01

    Introgen's adenoviral p53 gene therapy [INGN 201, ADVEXIN] is in clinical development for the treatment of various cancers. 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. INGN 201 has been shown to kill cancer cells directly. In August 2002, Introgen announced plans to file an application for INGN 201 with the European Agency for the Evaluation of Medicinal Products (EMEA) for the treatment of head and neck cancer; the European filing will be submitted simultaneously with the previously scheduled (planned for 2004) submission of a Biologics License Application (BLA) for ADVEXIN to the US FDA. On 20 February 2003, INGN 201 received orphan drug designation from the US FDA for head and neck cancer. INGN 201 is available for licensing although Introgen favours retaining partial or full rights to the therapy in the US. Introgen Therapeutics and its collaborative partner for the p53 programme, Aventis Gencell, have been developing p53 gene therapy products. The agreement was originally signed by Rhône-Poulenc Rorer's Gencell division, which became Aventis Gencell after Rhône-Poulenc Rorer merged with Hoechst Marion Roussel to form Aventis Pharma. According to the original agreement, Introgen was responsible for phase I and preclinical development in North America, while Aventis Gencell was responsible for clinical trials conducted in Europe and for clinical trials in North America beyond phase I. In April 2001, Aventis Gencell and Introgen restructured their existing collaboration agreement for p53 gene therapy products. Aventis Gencell indicated that p53 research had suffered from internal competition for resources and was pulling back from its development agreement with Introgen for p53 gene therapy products. Introgen will assume responsibility for worldwide development of all p53 programmes and will obtain exclusive worldwide commercial rights to p53-based gene therapy

  11. Effects of Chronic Ochratoxin A Exposure on p53 Heterozygous and p53 Homozygous Mice.

    Science.gov (United States)

    Bondy, Genevieve S; Caldwell, Donald S; Aziz, Syed A; Coady, Laurie C; Armstrong, Cheryl L; Curran, Ivan H A; Koffman, Robyn L; Kapal, Kamla; Lefebvre, David E; Mehta, Rekha

    2015-07-01

    Exposure to the mycotoxin ochratoxin A (OTA) causes nephropathy in domestic animals and rodents and renal tumors in rodents and poultry. Humans are exposed to OTA by consuming foods made with contaminated cereal grains and other commodities. Management of human health risks due to OTA exposure depends, in part, on establishing a mode of action (MOA) for OTA carcinogenesis. To further investigate OTA's MOA, p53 heterozygous (p53+/-) and p53 homozygous (p53+/+) mice were exposed to OTA in diet for 26 weeks. The former are susceptible to tumorigenesis upon chronic exposure to genotoxic carcinogens. OTA-induced renal damage but no tumors were observed in either strain, indicating that p53 heterozygosity conferred little additional sensitivity to OTA. Renal changes included dose-dependent increases in cellular proliferation, apoptosis, karyomegaly, and tubular degeneration in proximal tubules, which were consistent with ochratoxicosis. The lowest observed effect level for renal changes in p53+/- and p53+/+ mice was 200 μg OTA/kg bw/day. Based on the lack of tumors and the severity of renal and body weight changes at a maximum tolerated dose, the results were interpreted as suggestive of a primarily nongenotoxic (epigenetic) MOA for OTA carcinogenesis in this mouse model.

  12. The p53 Isoform Δ133p53β Promotes Cancer Stem Cell Potential

    Directory of Open Access Journals (Sweden)

    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.

  13. 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.

  14. 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.

  15. P53 regulates disruption of neuronal development in the adult hippocampus after irradiation

    Science.gov (United States)

    Li, Y-Q; Cheng, ZW-C; Liu, SK-W; Aubert, I; Wong, C S

    2016-01-01

    Inhibition of hippocampal neurogenesis is implicated in neurocognitive dysfunction after cranial irradiation for brain tumors. How irradiation results in impaired neuronal development remains poorly understood. The Trp53 (p53) gene is known to regulate cellular DNA damage response after irradiation. Whether it has a role in disruption of late neuronal development remains unknown. Here we characterized the effects of p53 on neuronal development in adult mouse hippocampus after irradiation. Different bromodeoxyuridine incorporation paradigms and a transplantation study were used for cell fate mapping. Compared with wild-type mice, we observed profound inhibition of hippocampal neurogenesis after irradiation in mice deficient in p53 despite the absence of acute apoptosis of neuroblasts. The putative neural stem cells were apoptosis resistant after irradiation regardless of p53 genotype. Cell fate mapping using different bromodeoxyuridine incorporation paradigms revealed enhanced activation of neural stem cells and their consequential exhaustion in the absence of p53 after irradiation. Both p53-knockout and wild-type mice demonstrated similar extent of microglial activation in the hippocampus after irradiation. Impairment of neuronal differentiation of neural progenitors transplanted in irradiated hippocampus was not altered by p53 genotype of the recipient mice. We conclude that by inhibiting neural progenitor activation, p53 serves to mitigate disruption of neuronal development after irradiation independent of apoptosis and perturbation of the neural stem cell niche. These findings suggest for the first time that p53 may have a key role in late effects in brain after irradiation.

  16. 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.

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

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    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. 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

  19. Status quo of p53 in the treatment of tumors.

    Science.gov (United States)

    Guan, Yong-Song; He, Qing; Zou, Qing

    2016-10-01

    The p53 gene is pivotal for oncogenesis in a combination of mutations in oncogenes and antioncogenes. The ubiquitous loss of the p53 pathway in human cancers has generated considerable interest in developing p53-targeted cancer therapies, but current ideas and approaches targeting p53 are conflicting. Current researches focus on cancer-selective drugs with therapeutic strategies that both activate and inhibit p53. As p53 is ubiquitously lost in human cancers, the strategy of exogenous p53 addition is reasonable. However, p53 acts not equally in all cell types; thus, individualized p53 therapy is the direction of future research. To clarify the controversies on p53 for improvement of future antitumor studies, the review focuses on the available technological protocols, including their advantages and limitations in terms of future therapeutic use of p53 in the management of tumors.

  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. 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.

    Science.gov (United States)

    Demma, Mark; Maxwell, Eugene; Ramos, Robert; Liang, Lianzhu; Li, Cheng; Hesk, David; Rossman, Randall; Mallams, Alan; Doll, Ronald; Liu, Ming; Seidel-Dugan, Cynthia; Bishop, W Robert; Dasmahapatra, Bimalendu

    2010-04-02

    Abrogation of p53 function occurs in almost all human cancers, with more than 50% of cancers harboring inactivating mutations in p53 itself. Mutation of p53 is indicative of highly aggressive cancers and poor prognosis. The vast majority of mutations in p53 occur in its core DNA binding domain (DBD) and result in inactivation of p53 by reducing its thermodynamic stability at physiological temperature. Here, we report a small molecule, SCH529074, that binds specifically to the p53 DBD in a saturable manner with an affinity of 1-2 microm. Binding restores wild type function to many oncogenic mutant forms of p53. This small molecule reactivates mutant p53 by acting as a chaperone, in a manner similar to that previously reported for the peptide CDB3. Binding of SCH529074 to the p53 DBD is specifically displaced by an oligonucleotide with a sequence derived from the p53-response element. In addition to reactivating mutant p53, SCH529074 binding inhibits ubiquitination of p53 by HDM2. We have also developed a novel variant of p53 by changing a single amino acid in the core domain of p53 (N268R), which abolishes binding of SCH529074. This amino acid change also inhibits HDM2-mediated ubiquitination of p53. Our novel findings indicate that through its interaction with p53 DBD, SCH529074 restores DNA binding activity to mutant p53 and inhibits HDM2-mediated ubiquitination.

  2. 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.

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

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    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

  4. 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.

  5. Studies of association of variants near the HHEX, CDKN2A/B, and IGF2BP2 genes with type 2 diabetes and impaired insulin release in 10,705 Danish subjects

    DEFF Research Database (Denmark)

    Grarup, Niels; Rose, Chrisian S; Andersson, Ehm A

    2007-01-01

    In the present study, we aimed to validate the type 2 diabetes susceptibility alleles identified in six recent genome-wide association studies in the HHEX/KIF11/IDE (rs1111875), CDKN2A/B (rs10811661), and IGF2BP2 (rs4402960) loci, as well as the intergenic rs9300039 variant. Furthermore, we aimed...

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

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    Jesionek-Kupnicka Dorota

    2009-08-01

    Full Text Available Abstract Background 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. Methods 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. Results 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. Conclusion 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.

  7. Transcriptional repression in normal human keratinocytes by wild-type and mutant p53.

    Science.gov (United States)

    Alvarez-Salas, L M; Velazquez, A; Lopez-Bayghen, E; Woodworth, C D; Garrido, E; Gariglio, P; DiPaolo, J A

    1995-05-01

    Wild-type p53 is a nuclear phosphoprotein that inhibits cell proliferation and represses transcriptionally most TATA box-containing promoters in transformed or tumor-derived cell lines. This study demonstrates that p53 alters transcription of the long control region (LCR) of human papillomavirus type 18 (HPV-18). Wild-type and mutant p53 143Val to Ala repressed the HPV-18 LCR promoter in normal human keratinocytes, the natural host cell for HPV infections. Repression by wild-type p53 was also observed in C-33A cells and in an HPV-16-immortalized cell line with an inducible wild-type p53. However, when C-33A cells were cotransfected with the HPV-18 LCR and mutant 143Val to Ala, repression did not occur. Mutant p53 135Cys to Ser did not induce repression in either normal human keratinocytes or in the C-33A line; although like 143Val to Ala, it is thought to affect the DNA binding activity of the wild-type protein. The ability of mutant p53 143Val to Ala to inactivate the HPV early promoter in normal cells (by approximately 60% reduction) suggests that this mutant may be able to associate with wild-type p53 and interact with TATA box-binding proteins. Therefore, these results demonstrate that the transcriptional activities of p53 mutants may be dependent upon the cell type assayed and the form of its endogenous p53. Furthermore, normal human keratinocytes represent an alternative model for determining the activities of p53 mutants.

  8. Inactivation of CDKN2A gene in larynx cancer patients and its clinical significance.%CDKN2A基因失活对喉癌的影响及其临床意义

    Institute of Scientific and Technical Information of China (English)

    曹婧; 王亚辉; 刘红; 司迎; 张雅美; 关庆捷

    2011-01-01

    Objective To study the inactivation of cyclindependent kinase inhibitor 2A ( CDKN 2A) gene and to analyze its clinical significance in larynx cancer. Methods The rejected tissues of larynx cancer surgery and non - tumor larynx tissue were collected from 68 patients. The expression of CDKN2A was assayed by the semiquantitative counter reverse transcription polymerase chain rcaction ( RT - PCR). The protein expresssion of CDKN2A was determined by Western blot analysis. The relationship between CDKN2A expression and the occurrence and development of larynx cancer was analyzed. Results ( 1 ) The CDKN2A mRNA expression in laryngeal carcinoma was significantly less than that in non -tumor laryngeal tissues (P<0.05). (2)The expression of CDKN2A protein in laryngeal carcinoma was significantly lower than that in non - tumor laryngeal tissues ( the low expression rates were 80.9% and 47.1%, respectively,and the lower expression rates were 52.9% and 22.1%, respectively ,P <0. 05). The expression was not related to pathological types. (3)Western blot analysis showed that the CDKN2A protein expression in laryngeal carcinoma was significantly lower than that in non - minor laryngeal tissues ( t = 3.246, P < O. 05). Conclusion The CDKN2A gene mutation and inactivation of its encoded protein are related to the development of laryngeal cancer significantly.%目的 研究细胞周期依赖性激酶抑制基因(CDKN2A)失活对喉癌的影响及其临床意义.方法 应用半定量反转录聚合酶链反应(RT-PCR)和免疫印迹分析法检测喉癌手术切除组织68例,非肿瘤喉部组织68例,观察CDKN2A基因失活与喉癌发生发展的关系.结果 (1)喉癌组织CDKN2A mRNA表达明显少于非肿瘤喉组织(P<0.05);(2)喉癌组织中CDKN2A蛋白的表达明显低于非肿瘤喉组织,差异有统计学意义(两者的低表达率为80.9%、47.1%,过低表达率为52.9%、22.1%,P<0.05),并与病理分型无关;(3)Western blot电泳结果半定量

  9. Targeting the p53 Pathway in Ewing Sarcoma

    OpenAIRE

    Neilsen, Paul M.; Pishas, Kathleen I.; Callen, David F; Thomas, David M.

    2011-01-01

    The p53 tumour suppressor plays a pivotal role in the prevention of oncogenic transformation. Cancers frequently evade the potent antitumour surveillance mechanisms of p53 through mutation of the TP53 gene, with approximately 50% of all human malignancies expressing dysfunctional, mutated p53 proteins. Interestingly, genetic lesions in the TP53 gene are only observed in 10% of Ewing Sarcomas, with the majority of these sarcomas expressing a functional wild-type p53. In addition, the p53 downs...

  10. Occupational health hazards of trichloroethylene among workers in relation to altered mRNA expression of cell cycle regulating genes (p53, p21, bax and bcl-2 and PPARA

    Directory of Open Access Journals (Sweden)

    Meenu Varshney

    2015-01-01

    Full Text Available Trichloroethylene (TCE is widely used as a metal degreaser in industrial processes. The present study reports on the effects of TCE exposure on workers employed in the lock industries. To ensure exposure of the workers to TCE, its toxic metabolites, trichloroacetic acid (TCA, dichloroacetic acid (DCA and trichloroethanol (TCEOH were detected in the plasma of the subjects through solid phase microextraction-gas chromatography-electron capture detection. TCA, DCA and TCEOH were detected in the range of 0.004–2.494 μg/mL, 0.01–3.612 μg/mL and 0.002–0.617 μg/mL, respectively. Quantitative reverse transcription polymerase chain reaction analysis revealed up-regulated expression of p53 (2.4-fold; p < 0.05, p21 (2-fold; p < 0.01, bax (2.9-fold; p < 0.01 mRNAs and down-regulated expression of bcl-2 (67%; p < 0.05 mRNAs, indicating DNA damaging potential of these metabolites. No effects were observed on the levels of p16 and c-myc mRNAs. Further, as TCA and DCA, the ligand of peroxisome proliferator activated receptor alpha (PPARA, are involved in the process of hepatocarcinogenesis in rodents, we examined expression of PPARA mRNA and let-7c miRNA in the workers. No statistically significant differences in expression of PPARA mRNA and let-7c miRNA in patients were observed as compared to values in controls. Dehydroepiandosterone sulfate (DHEAS is a reported endogenous ligand of PPARA so its competitive role was also studied. We observed decreased levels of DHEAS hormone in the subjects. Hence, its involvement in mediation of the observed changes in the levels of various mRNAs analyzed in this study appears unlikely.

  11. Mouse modeling of the MDM2/MDMX-p53 signaling axis.

    Science.gov (United States)

    Tackmann, Nicole R; Zhang, Yanping

    2017-01-17

    It is evident that p53 activity is critical for tumor prevention and stress response through its transcriptional activation of genes affecting cellular senescence, apoptosis, cellular metabolism, and DNA repair. The regulation of p53 is highly complex, and MDM2 and MDMX are thought to be critical for deciding the fate of p53, both through inhibitory binding and posttranslational modification. Many mouse models have been generated to study the regulation of p53 in vivo, and they have altered our interpretations of how p53 is regulated by MDM2 and MDMX. Although MDM2 is absolutely required for p53 regulation, certain functions are dispensable under unstressed conditions, including the ability of MDM2 to degrade p53. MDMX, on the other hand, may only be required in select situations, like embryogenesis. These models have also clarified how cellular stress signals modify the p53-inhibiting activities of MDM2 and MDMX in vivo It is clear that more work will need to be performed to further understand the contexts for each of these signals and the requirements of various MDM2 and MDMX functions. Here, we will discuss what we have learned from mouse modeling of MDM2 and MDMX and underscore the ways in which these models could inform future therapies.

  12. p53 pathway is involved in cell competition during mouse embryogenesis.

    Science.gov (United States)

    Zhang, Guoxin; Xie, Yinyin; Zhou, Ying; Xiang, Cong; Chen, Lai; Zhang, Chenxi; Hou, Xiaoshuang; Chen, Jiong; Zong, Hui; Liu, Geng

    2017-01-17

    The function of tumor suppressor p53 has been under intense investigation. Acute stresses such as DNA damage are able to trigger a high level of p53 activity, leading to cell cycle arrest or apoptosis. In contrast, the cellular response of mild p53 activity induced by low-level stress in vivo remains largely unexplored. Murine double minute (MDM)2 and MDM4 are two major negative regulators of p53. Here, we used the strategy of haploinsufficiency of Mdm2 and Mdm4 to induce mild p53 activation in vivo and found that Mdm2(+/-)Mdm4(+/-) double-heterozygous mice exhibited normal embryogenesis. However, closer examination demonstrated that the Mdm2(+/-)Mdm4(+/-) cells exhibited a growth disadvantage and were outcompeted during development in genetic mosaic embryos that contained wild-type cells. Further study indicated the out-competition phenotype was dependent on the levels of p53. These observations revealed that cells with mild p53 activation were less fit and exhibited altered fates in a heterotypic environment, resembling the cell competition phenomenon first uncovered in Drosophila By marking unfit cells for elimination, p53 may exert its physiological role to ensure organ and animal fitness.

  13. Evaluation of feline oral squamous cell carcinomas for p16CDKN2A protein immunoreactivity and the presence of papillomaviral DNA.

    Science.gov (United States)

    Munday, John S; Knight, Cameron G; French, Adrienne F

    2011-04-01

    Oral squamous cell carcinomas (OSCCs) develop commonly in cats. While the cause of the feline neoplasms is unknown, a quarter of human OSCCs are caused by papillomavirus (PV) infection. As PV DNA has been previously detected in a feline OSCC, it was hypothesised that PV infection could be a significant cause of feline OSCCs. Human OSCCs that are caused by PVs contain increased p16(CDKN2A) protein (p16), which can be detected using immunohistochemistry. In cats, increased p16 immunoreactivity has been reported within PV-associated skin lesions. This study evaluated p16 immunoreactivity within 30 feline OSCCs. Additionally, PCR was used to amplify PV DNA from the OSCCs. Increased p16 immunoreactivity was present within 2 OSCCs. However, as PV DNA was not amplified from any OSCC in this study, it cannot be confirmed that the increased p16 was caused by PV infection. Therefore, these results do not support the hypothesis that PVs are a significant cause of OSCCs in cats. Loss of p16 expression is considered an important process in the development of human non-PV-induced OSCCs. In contrast, loss of p16 immunoreactivity was only present in 2 feline OSCCs. This suggests that human and feline OSCCs develop due to different molecular mechanisms.

  14. p53 protein aggregation promotes platinum resistance in ovarian cancer.

    Science.gov (United States)

    Yang-Hartwich, Y; Soteras, M G; Lin, Z P; Holmberg, J; Sumi, N; Craveiro, V; Liang, M; Romanoff, E; Bingham, J; Garofalo, F; Alvero, A; Mor, G

    2015-07-01

    High-grade serous ovarian carcinoma (HGSOC), the most lethal gynecological cancer, often leads to chemoresistant diseases. The p53 protein is a key transcriptional factor regulating cellular homeostasis. A majority of HGSOCs have inactive p53 because of genetic mutations. However, genetic mutation is not the only cause of p53 inactivation. The aggregation of p53 protein has been discovered in different types of cancers and may be responsible for impairing the normal transcriptional activation and pro-apoptotic functions of p53. We demonstrated that in a unique population of HGSOC cancer cells with cancer stem cell properties, p53 protein aggregation is associated with p53 inactivation and platinum resistance. When these cancer stem cells differentiated into their chemosensitive progeny, they lost tumor-initiating capacity and p53 aggregates. In addition to the association of p53 aggregation and chemoresistance in HGSOC cells, we further demonstrated that the overexpression of a p53-positive regulator, p14ARF, inhibited MDM2-mediated p53 degradation and led to the imbalance of p53 turnover that promoted the formation of p53 aggregates. With in vitro and in vivo models, we demonstrated that the inhibition of p14ARF could suppress p53 aggregation and sensitize cancer cells to platinum treatment. Moreover, by two-dimensional gel electrophoresis and mass spectrometry we discovered that the aggregated p53 may function uniquely by interacting with proteins that are critical for cancer cell survival and tumor progression. Our findings help us understand the poor chemoresponse of a subset of HGSOC patients and suggest p53 aggregation as a new marker for chemoresistance. Our findings also suggest that inhibiting p53 aggregation can reactivate p53 pro-apoptotic function. Therefore, p53 aggregation is a potential therapeutic target for reversing chemoresistance. This is paramount for improving ovarian cancer patients' responses to chemotherapy, and thus increasing their

  15. 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.

  16. 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...... 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...... 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...

  17. USP11通过去泛素化p53调控p53稳定性%USP11 regulates p53 stability by deubiquitinating p53

    Institute of Scientific and Technical Information of China (English)

    Jia-ying KE; Cong-jie DAI; Wen-lin WU; Jin-hua GAO; Ai-juan XIA; Guang-ping LIU; Kao-sheng LV; Chun-lin WU

    2014-01-01

    The p53 tumor suppressor protein coordinates the celular responses to a broad range of celular stresses, leading to DNA repair, cel cycle arrest or apoptosis. The stability of p53 is essential for its tumor suppressor function, which is tightly controlled by ubiquitin-dependent degradation primarily through its negative regulator murine double minute 2 (Mdm2). To better understand the regulation of p53, we tested the interaction between p53 and USP11 using co-immunoprecipitation. The results show that USP11, an ubiquitin-specific protease, forms specific complexes with p53 and stabilizes p53 by deubiquitinating it. Moreover, down-regulation of USP11 dramaticaly attenuated p53 in-duction in response to DNA damage stress. These findings reveal that USP11 is a novel regulator of p53, which is required for p53 activation in response to DNA damage.

  18. Deconstructing p53 transcriptional networks in tumor suppression.

    Science.gov (United States)

    Bieging, Kathryn T; Attardi, Laura D

    2012-02-01

    p53 is a pivotal tumor suppressor that induces apoptosis, cell-cycle arrest and senescence in response to stress signals. Although p53 transcriptional activation is important for these responses, the mechanisms underlying tumor suppression have been elusive. To date, no single or compound mouse knockout of specific p53 target genes has recapitulated the dramatic tumor predisposition that characterizes p53-null mice. Recently, however, analysis of knock-in mice expressing p53 transactivation domain mutants has revealed a group of primarily novel direct p53 target genes that may mediate tumor suppression in vivo. We present here an overview of well-known p53 target genes and the tumor phenotypes of the cognate knockout mice, and address the recent identification of new p53 transcriptional targets and how they enhance our understanding of p53 transcriptional networks central for tumor suppression.

  19. Nuclear inclusion bodies of mutant and wild-type p53 in cancer: a hallmark of p53 inactivation and proteostasis remodeling by p53 aggregation.

    Science.gov (United States)

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

    2016-12-30

    Although p53 protein aggregates have been observed in cancer cell lines and tumour tissue, their impact in cancer remains largely unknown. Here, we extensively screened for p53 aggregation phenotypes in tumour biopsies and identified nuclear inclusion bodies (nIBs) of transcriptionally inactive mutant or wild-type p53 as the most frequent aggregation-like phenotype across six different cancer types. p53-positive nIBs co-stained with nuclear aggregation markers and shared molecular hallmarks of nIBs commonly found in neurodegenerative disorders. In cell culture, tumour-associated stress was a strong inducer of p53 aggregation and nuclear inclusion body formation. This was most prominent for mutant p53, but could also be observed in wild-type p53 cell lines for which nIB formation correlated to the loss of p53s transcriptional activity. Importantly, protein aggregation also fueled the dysregulation of the proteostasis network in the tumour cell by inducing a hyper-activated, oncogenic heat-shock response to which tumours are commonly addicted, and by overloading the proteasomal degradation system, an observation that was most pronounced for structurally destabilized mutant p53. Patients exhibiting tumours with p53-positive nIBs suffered from a poor clinical outcome similar to loss-of-p53-expression, and tumour biopsies displayed a differential proteostatic expression profile associated to p53-nIBs. p53-positive nIBs therefore highlight a malignant state of the tumour that results from the interplay between (i) the functional inactivation of p53 through mutation and/or aggregation and (ii) microenvironmental stress, a combination that catalyses proteostatic dysregulation. This study highlights several unexpected clinical, biological and therapeutically unexplored parallels between cancer and neurodegeneration.

  20. Mechanisms that enhance sustainability of p53 pulses.

    Directory of Open Access Journals (Sweden)

    Jae Kyoung Kim

    Full Text Available The tumor suppressor p53 protein shows various dynamic responses depending on the types and extent of cellular stresses. In particular, in response to DNA damage induced by γ-irradiation, cells generate a series of p53 pulses. Recent research has shown the importance of sustaining repeated p53 pulses for recovery from DNA damage. However, far too little attention has been paid to understanding how cells can sustain p53 pulses given the complexities of genetic heterogeneity and intrinsic noise. Here, we explore potential molecular mechanisms that enhance the sustainability of p53 pulses by developing a new mathematical model of the p53 regulatory system. This model can reproduce many experimental results that describe the dynamics of p53 pulses. By simulating the model both deterministically and stochastically, we found three potential mechanisms that improve the sustainability of p53 pulses: 1 the recently identified positive feedback loop between p53 and Rorα allows cells to sustain p53 pulses with high amplitude over a wide range of conditions, 2 intrinsic noise can often prevent the dampening of p53 pulses even after mutations, and 3 coupling of p53 pulses in neighboring cells via cytochrome-c significantly reduces the chance of failure in sustaining p53 pulses in the presence of heterogeneity among cells. Finally, in light of these results, we propose testable experiments that can reveal important mechanisms underlying p53 dynamics.

  1. 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.

  2. Glycogen synthase kinase3 beta phosphorylates serine 33 of p53 and activates p53's transcriptional activity

    Directory of Open Access Journals (Sweden)

    Price Brendan D

    2001-07-01

    Full Text Available Abstract Background The p53 protein is activated by genotoxic stress, oncogene expression and during senescence, p53 transcriptionally activates genes involved in growth arrest and apoptosis. p53 activation is regulated by post-translational modification, including phosphorylation of the N-terminal transactivation domain. Here, we have examined how Glycogen Synthase Kinase (GSK3, a protein kinase involved in tumorigenesis, differentiation and apoptosis, phosphorylates and regulates p53. Results The 2 isoforms of GSK3, GSK3α and GSK3β, phosphorylate the sequence Ser-X-X-X-Ser(P when the C-terminal serine residue is already phosphorylated. Several p53 kinases were examined for their ability to create GSK3 phosphorylation sites on the p53 protein. Our results demonstrate that phosphorylation of serine 37 of p53 by DNA-PK creates a site for GSK3β phosphorylation at serine 33 in vitro. GSK3α did not phosphorylate p53 under any condition. GSK3β increased the transcriptional activity of the p53 protein in vivo. Mutation of either serine 33 or serine 37 of p53 to alanine blocked the ability of GSK3β to regulate p53 transcriptional activity. GSK3β is therefore able to regulate p53 function in vivo. p53's transcriptional activity is commonly increased by DNA damage. However, GSK3β kinase activity was inhibited in response to DNA damage, suggesting that GSK3β regulation of p53 is not involved in the p53-DNA damage response. Conclusions GSK3β can regulate p53's transcriptional activity by phosphorylating serine 33. However, GSK3β does not appear to be part of the p53-DNA damage response pathway. Instead, GSK3β may provide the link between p53 and non-DNA damage mechanisms for p53 activation.

  3. 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.

  4. The p53 inhibitor Mdm4 cooperates with multiple genetic lesions in tumourigenesis.

    Science.gov (United States)

    Xiong, Shunbin; Pant, Vinod; Zhang, Yun; Aryal, Neeraj K; You, M James; Kusewitt, Donna; Lozano, Guillermina

    2017-03-01

    The p53 inhibitor Mdm4 is present at high levels in multiple human cancers. Overexpression of Mdm4 in mice drives the spontaneous development of mostly lymphomas and sarcomas. In this study, we explored the ability of Mdm4 to cooperate with lesions in tumour development. The Mdm4 transgene contributed to mammary tumour development in a BALB/cJ background. High levels of Mdm4 enhanced tumour development in a mutant p53R172H heterozygous background, and reduced the need to lose the wild-type p53 allele, as compared with mice heterozygous only for the p53R172H mutation. Additionally, high levels of Mdm4 cooperated with an oncogenic K-ras mutation to drive lung tumourigenesis in vivo. Finally, we examined p53-independent functions of Mdm4 by studying the contribution of Mdm4 to tumour development in the absence of p53. Whereas the overall survival times of p53-null mice with and without the Mdm4 transgene were similar, male mice with both alterations showed significantly shorter survival than p53-null male mice, and showed differences in tumour spectrum, demonstrating a p53-independent function of Mdm4 in tumourigenesis. Furthermore, p53-null mice with the highest level of Mdm4 tended to have multiple tumours. Thus, a detailed analysis of Mdm4 transgenic mice in various genetic backgrounds shows synergy in tumour development in vivo. Mdm4 may thus serve as a therapeutic target in cancers. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  5. SV40 large T-p53 complex: evidence for the presence of two immunologically distinct forms of p53

    Energy Technology Data Exchange (ETDEWEB)

    Milner, J.; Gamble, J.

    1985-11-01

    The transforming protein of SV40 is the large T antigen. Large T binds a cellular protein, p53, which is potentially oncogenic by virtue of its functional involvement in the control of cell proliferation. This raises the possibility that p53 may mediate, in part, the transforming function of SV40 large T. Two immunologically distinct forms of p53 have been identified in normal cells: the forms are cell-cycle dependent, one being restricted to nondividing cells (p53-Go) and the second to dividing cells (p53-G divided by). The authors have now dissociated and probed the multimeric complex of SV40 large T-p53 for the presence of immunologically distinct forms of p53. Here they present evidence for the presence of p53-Go and p53-G divided by complexed with SV40 large T.

  6. 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...

  7. TBP-like Protein (TLP) Disrupts the p53-MDM2 Interaction and Induces Long-lasting p53 Activation.

    Science.gov (United States)

    Maeda, Ryo; Tamashiro, Hiroyuki; Takano, Kazunori; Takahashi, Hiro; Suzuki, Hidefumi; Saito, Shinta; Kojima, Waka; Adachi, Noritaka; Ura, Kiyoe; Endo, Takeshi; Tamura, Taka-Aki

    2017-02-24

    Stress-induced activation of p53 is an essential cellular response to prevent aberrant cell proliferation and cancer development. The ubiquitin ligase MDM2 promotes p53 degradation and limits the duration of p53 activation. It remains unclear, however, how p53 persistently escapes MDM2-mediated negative control for making appropriate cell fate decisions. Here we report that TBP-like protein (TLP), a member of the TBP family, is a new regulatory factor for the p53-MDM2 interplay and thus for p53 activation. We found that TLP acts to stabilize p53 protein to ensure long-lasting p53 activation, leading to potentiation of p53-induced apoptosis and senescence after genotoxic stress. Mechanistically, TLP interferes with MDM2 binding and ubiquitination of p53. Moreover, single cell imaging analysis shows that TLP depletion accelerates MDM2-mediated nuclear export of p53. We further show that a cervical cancer-derived TLP mutant has less p53 binding ability and lacks a proliferation-repressive function. Our findings uncover a role of TLP as a competitive MDM2 blocker, proposing a novel mechanism by which p53 escapes the p53-MDM2 negative feedback loop to modulate cell fate decisions.

  8. 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.

  9. 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.

  10. Papillomaviral DNA and increased p16CDKN2A protein are frequently present within feline cutaneous squamous cell carcinomas in ultraviolet-protected skin.

    Science.gov (United States)

    Munday, John S; Gibson, Isobel; French, Adrienne F

    2011-08-01

    Squamous cell carcinomas (SCCs) are common feline skin tumours. While exposure to ultraviolet (UV) light causes some SCCs, a subset develop in UV-protected skin. In cats, papillomaviruses (PVs) cause viral plaques and Bowenoid in situ carcinomas (BISCs). As both may progress to SCC, it was hypothesized that SCCs in UV-protected skin may represent neoplastic transformation of a PV-induced lesion. To investigate this hypothesis, PCR was used to amplify PV DNA from 25 UV-protected and 45 UV-exposed SCCs. Oncogenic human PVs cause neoplasia by mechanisms that also increase p16(CDKN2A) protein (p16). As increased p16 is present in feline viral plaques and BISCs, immunohistochemistry was used to detect p16 within the SCCs. Papillomaviral DNA was amplified from 76% of UV-protected SCCs, but only 42% of UV-exposed SCCs. Increased p16 was present in 84% of UV-protected SCCs, but only 40% of UV-exposed SCCs. The more frequent detection of PV DNA and increased p16 within UV-protected SCCs supports the hypothesis that some develop from a PV-induced plaque or BISC. Felis domesticus PV-2 is thought to cause viral plaques and BISCs. This PV was detected most frequently within the UV-protected SCCs, supporting development from a PV-induced lesion. Increased p16 and PV DNA were less frequent within UV-exposed SCCs, presumably because these developed from actinic keratosis rather than a PV-induced lesion. The results support the hypothesis that some feline cutaneous SCCs are caused by PV infection and suggest that PVs may cause neoplasia by mechanisms that also increase p16.

  11. Increased p16CDKN2A protein within feline cutaneous viral plaques, bowenoid in situ carcinomas, and a subset of invasive squamous cell carcinomas.

    Science.gov (United States)

    Munday, J S; French, A F; Peters-Kennedy, J; Orbell, G M B; Gwynne, K

    2011-03-01

    Cutaneous viral plaques and bowenoid in situ carcinomas (BISCs) in cats are thought to be caused by papillomavirus (PV) infection. There is evidence that PVs may also cause some feline invasive squamous cell carcinomas (ISCCs). Human oncogenic PVs degrade retinoblastoma (RB) protein, impairing cell cycle control. Loss of RB function also increases p16(CDKN2A) protein (p16), and increased p16 immunoreactivity within a human oral ISCC indicates that the neoplasm was caused by PV infection. In the present study, p16 immunoreactivity was evaluated in 14 feline viral plaques, 14 BISCs, 7 non-solar-induced ISCCs, 11 solar-induced ISCCs, and 14 trichoblastomas. Increased p16 was present within all viral plaques, BISCs, and non-solar-induced ISCCs. In contrast, little p16 immunoreactivity was visible in the solar-induced ISCCs or trichoblastomas. PV DNA was consistently amplified from viral plaques, BISCs, and non-solar-induced ISCCs. However, just 5 solar-induced ISCCs and 1 trichoblastoma contained PV DNA. Given that both increased p16 immunoreactivity and PV DNA were present within viral plaques, BISCs, and non-solar-induced ISCCs, all 3 may be caused by PV infection. This suggests that feline non-solar-induced ISCCs may develop as a result of neoplastic progression from viral plaques and BISCs. Whether PVs promote this progression is unknown; however, evidence from this study suggests the PV that is associated with viral plaques and BISCs is able to disrupt the p16-RB pathway and therefore could have oncogenic potential. Immunohistochemical detection of p16 appears to be a useful technique to investigate the role of PVs in feline skin disease.

  12. Expression of wild-type p53 is not compatible with continued growth of p53-negative tumor cells.

    OpenAIRE

    Johnson, P; Gray, D.; Mowat, M; Benchimol, S

    1991-01-01

    Inactivation of the cellular p53 gene is a common feature of Friend virus-induced murine erythroleukemia cell lines and may represent a necessary step in the progression of this disease. As well, frequent loss or mutation of p53 alleles in diverse human tumors is consistent with the view of p53 as a tumor suppressor gene. To examine the significance of p53 gene inactivation in tumorigenesis, we have attempted to express transfected wild-type p53 in three p53-negative tumor cell lines: murine ...

  13. Overexpression of p53 mRNA in colorectal cancer and its relationship to p53 gene mutation.

    OpenAIRE

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

    1997-01-01

    We analysed the frequency of p53 mRNA overexpression in a series of 109 primary colorectal carcinomas and its association with p53 gene mutation, which has been correlated with short survival. Sixty-nine of the 109 cases (63%) demonstrated p53 mRNA overexpression, without any correlation with stage or site of disease. Comparison with p53 gene mutation indicated that, besides cases in which p53 gene mutation and p53 mRNA overexpression were either both present (40 cases) or both absent (36 cas...

  14. [P53 protein in adenocarcinoma of the large intestine].

    Science.gov (United States)

    Paluszkiewicz, P; Pawłowska-Wakowicz, B; Cybulski, M; Berbeć, H

    1997-01-01

    P53 gen mutations play significant role in neoplastic transformation of colorectal mucosa. We investigated p53 immunostaining in 80 cases of spontaneous human colorectal adenocarcinomas (with monoclonal DO7 antibody and LSAB+ kit). We found positive, nuclear p53 immunostaining in 64% of nonmucinous adenocarcinoma tissues and in 19% of mucinous adenocarcinomas tissues. P53 protein deposits were most often found in colorectal adenocarcinomas localised in rectum (66.67%) and in advanced (Dukes C, D) colorectal adenocarcinomas (59.38%) as well. There was no statistical significance between the p53 positive immunostaining and the histological differentiation of the colorectal adenocarcinomas. The overall survival of patients with tumours positive for p53 protein was significantly shorter than that of patients with colorectal cancers negative for p53 protein. We conclude that p53 immunohistochemical analysis may be treated as a supplementary prognostic marker for patients with colorectal adenocarcinoma, especially it may be useful for adjuvant therapy selection.

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

    OpenAIRE

    2014-01-01

    SUMMARY 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...

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

    OpenAIRE

    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 ...

  17. Mutant p53 promotes tumor progression and metastasis by the endoplasmic reticulum UDPase ENTPD5.

    Science.gov (United States)

    Vogiatzi, Fotini; Brandt, Dominique T; Schneikert, Jean; Fuchs, Jeannette; Grikscheit, Katharina; Wanzel, Michael; Pavlakis, Evangelos; Charles, Joël P; Timofeev, Oleg; Nist, Andrea; Mernberger, Marco; Kantelhardt, Eva J; Siebolts, Udo; Bartel, Frank; Jacob, Ralf; Rath, Ariane; Moll, Roland; Grosse, Robert; Stiewe, Thorsten

    2016-12-27

    Mutations in the p53 tumor suppressor gene are the most frequent genetic alteration in cancer and are often associated with progression from benign to invasive stages with metastatic potential. Mutations inactivate tumor suppression by p53, and some endow the protein with novel gain of function (GOF) properties that actively promote tumor progression and metastasis. By comparative gene expression profiling of p53-mutated and p53-depleted cancer cells, we identified ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a mutant p53 target gene, which functions as a uridine 5'-diphosphatase (UDPase) in the endoplasmic reticulum (ER) to promote the folding of N-glycosylated membrane proteins. A comprehensive pan-cancer analysis revealed a highly significant correlation between p53 GOF mutations and ENTPD5 expression. Mechanistically, mutp53 is recruited by Sp1 to the ENTPD5 core promoter to induce its expression. We show ENTPD5 to be a mediator of mutant p53 GOF activity in clonogenic growth, architectural tissue remodeling, migration, invasion, and lung colonization in an experimental metastasis mouse model. Our study reveals folding of N-glycosylated membrane proteins in the ER as a mechanism underlying the metastatic progression of tumors with mutp53 that could provide new possibilities for cancer treatment.

  18. Immunohistochemical study of p53, pRb, p16 in esophageal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zo, Jae Ill; Zo, Kyung Ja; Park, Jong Ho; Kim, Mi Hee [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1998-01-01

    To confirm the expression of molecular genetic alterations of p53, pRb, p16 in esophageal cancer and to investigate the expression of p53, pRb, p16 in esophageal cancer according to the pathologic steps of carcinogenesis, immuno-histochemistry was performed in 15 resected esophageal cancer specimens with multiple separated lesions after pathologic mapping. The accumulation of mutant p53 was observed in 60 % of dysplasia and 47 % of invasive cancer, while pRb was not detected in 91 % of dysplasia and 72.7 % of invasive cancer. But p16 was not observed in 0 % in dysplasia and 7 % of invasive cancer. But p16 was not observed in 0 % in dysplasia and 28.6 % in invasive cancer. There was no simultaneous negative pRb and p16 expression. There was no relations between p53 and p16, pRb. As a results, the expression of p53, pRb, p16 was co-related well with molecular genetic changes and inactivation of p53, pRb, p16 was co-related well with molecular genetic changes and inactivation of p53 and pRb was common and early event in esophageal carcinogenesis in Korea, but inactivation of p16 was a infrequent change. (author). 17 refs., 2 tabs., 7 figs

  19. p63 is required beside p53 for PERP-mediated apoptosis in uveal melanoma

    Science.gov (United States)

    Awais, Raheela; Spiller, David G; White, Michael R H; Paraoan, Luminita

    2016-01-01

    Background: PERP (p53 apoptosis effector related to PMP-22), a transcriptional target of p53, is downregulated and contributes to the impairment of apoptosis in uveal melanoma (UM). Intriguingly, PERP is not induced in UM despite functional p53. p63, located on chromosome 3, which is characteristically altered in high-risk UM, can transactivate PERP. Here, we determine the functional role of p63 expression in the initiation of p53/PERP-mediated apoptosis in UM. Methods: PERP expression was monitored by quantitative PCR (qPCR) and immunoblotting in UM cell lines treated with DNA-damaging agents. The functional role of p63 was assessed by transient expression of p63-turbo GFP (p63-tGFP) in the apoptosis- resistant, 3q-deficient OCM-1 cells. Expression and localisation of p63, PERP and p53, and induction of apoptosis were characterised by qPCR, immunoblotting and live cell confocal microscopy. Results: PERP expression was significantly downregulated in all UM cell lines. DNA-damaging treatments failed to induce apoptosis and activate PERP in OCM-1 cells, which displayed non-functional levels of p63. Expression of p63-tGFP induced apoptosis with marked increase in PERP expression and associated p53 accumulation. Conclusions: Lack of p63 contributes to reduced PERP levels and impaired p53-mediated apoptosis in UM. p63 expression is required for PERP-mediated apoptosis in UM. PMID:27584665

  20. 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

  1. 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

  2. P53 mutations and cancer: a tight linkage.

    Science.gov (United States)

    Perri, Francesco; Pisconti, Salvatore; Della Vittoria Scarpati, Giuseppina

    2016-12-01

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

  3. Mutant p53 protein localized in the cytoplasm inhibits autophagy.

    Science.gov (United States)

    Morselli, Eugenia; Tasdemir, Ezgi; Maiuri, Maria Chiara; Galluzzi, Lorenzo; Kepp, Oliver; Criollo, Alfredo; Vicencio, José Miguel; Soussi, Thierry; Kroemer, Guido

    2008-10-01

    The knockout, knockdown or chemical inhibition of p53 stimulates autophagy. Moreover, autophagy-inducing stimuli such as nutrient depletion, rapamycin or lithium cause the depletion of cytoplasmic p53, which in turn is required for the induction of autophagy. Here, we show that retransfection of p53(-/-) HCT 116 colon carcinoma cells with wild type p53 decreases autophagy down to baseline levels. Surprisingly, one third among a panel of 22 cancer-associated p53 single amino acid mutants also inhibited autophagy when transfected into p53(-/-) cells. Those variants of p53 that preferentially localize to the cytoplasm effectively repressed autophagy, whereas p53 mutants that display a prominently nuclear distribution failed to inhibit autophagy. The investigation of a series of deletion mutants revealed that removal of the DNA-binding domain from p53 fails to interfere with its role in the regulation of autophagy. Altogether, these results identify the cytoplasmic localization of p53 as the most important feature for p53-mediated autophagy inhibition. Moreover, the structural requirements for the two biological activities of extranuclear p53, namely induction of apoptosis and inhibition of autophagy, are manifestly different.

  4. 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.

  5. 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.

  6. Tumor suppressor p53 meets microRNAs

    OpenAIRE

    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 expr...

  7. Translational regulation of human p53 gene expression.

    OpenAIRE

    Fu, L.; Minden, M D; Benchimol, S

    1996-01-01

    In blast cells obtained from patients with acute myelogenous leukemia, p53 mRNA was present in all the samples examined while the expression of p53 protein was variable from patient to patient. Mutations in the p53 gene are infrequent in this disease and, hence, variable protein expression in the majority of the samples cannot be accounted for by mutation. In this study, we examined the regulation of p53 gene expression in human leukemic blasts and characterized the p53 transcripts in these c...

  8. The multiple levels of regulation by p53 ubiquitination

    OpenAIRE

    Lee, JT; Gu, W

    2010-01-01

    p53 is a central integrator of a plethora of signals and outputs these signals in the form of tumor suppression. It is well accepted that ubiquitination plays a major part in p53 regulation. Nonetheless, the molecular mechanisms by which p53 activity is controlled by ubiquitination are complex. Mdm2, a RING oncoprotein, was once thought to be the sole E3 ubiquitin ligase for p53, however recent studies have shown that p53 is stabilized but still degraded in the cells of Mdm2-null mice. Althou...

  9. 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.

  10. p53 Over-expression and p53 mutations in colon carcinomas: Relation to dietary risk factors

    NARCIS (Netherlands)

    Voskuil, D.W.; Kampman, E.; Kraats, A.A. van; Balder, H.F.; Muijen, G.N.P. van; Goldbohm, R.A.; Veer, P. van 't

    1999-01-01

    Epidemiological studies have suggested that dietary factors may differently affect p53-dependent and p53-independent pathways to colon cancer. Results of such studies may depend on the method used to assess p53 status. This case-control study of 185 colon-cancer cases and 259 controls examines this

  11. Knockin mice expressing a chimeric p53 protein reveal mechanistic differences in how p53 triggers apoptosis and senescence

    OpenAIRE

    2008-01-01

    The contribution of transcriptional activation to the p53 effector functions critical for tumor suppression, apoptosis and cellular senescence, remains unclear because of p53's ability to regulate diverse cellular processes in a transactivation-independent manner. Dissociating the importance of transactivation from other p53 functions, including regulating transcriptional repression, DNA replication, homologous recombination, centrosome duplication, and mitochondrial function, has been diffic...

  12. 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.

  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. Chemical Variations on the p53 Reactivation Theme

    Directory of Open Access Journals (Sweden)

    Carlos J. A. Ribeiro

    2016-05-01

    Full Text Available Among the tumor suppressor genes, p53 is one of the most studied. It is widely regarded as the “guardian of the genome”, playing a major role in carcinogenesis. In fact, direct inactivation of the TP53 gene occurs in more than 50% of malignancies, and in tumors that retain wild-type p53 status, its function is usually inactivated by overexpression of negative regulators (e.g., MDM2 and MDMX. Hence, restoring p53 function in cancer cells represents a valuable anticancer approach. In this review, we will present an updated overview of the most relevant small molecules developed to restore p53 function in cancer cells through inhibition of the p53-MDMs interaction, or direct targeting of wild-type p53 or mutated p53. In addition, optimization approaches used for the development of small molecules that have entered clinical trials will be presented.

  15. The tumor suppressor p53 connects ribosome biogenesis to cell cycle control: a double-edged sword.

    Science.gov (United States)

    Hölzel, Michael; Burger, Kaspar; Mühl, Bastian; Orban, Mathias; Kellner, Markus; Eick, Dirk

    2010-05-01

    Since its first description more than 30 years ago p53 has become a paradigm for a protein with versatile functions. P53 sensitizes a large variety of genetic alterations and has been entitled the guardian of the genome. Stabilization of p53 upon DNA damage is accompanied by a complex pattern of modifications, which ascertain the cellular response either in the direction of a reversible or irreversible cell cycle arrest or programmed cell death. More recently it became evident that p53 also responds to non-genotoxic cell stress, in particular if ribosome biogenesis is affected.

  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. 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....... 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...... 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...

  18. A Cohort Study of p53 Mutations and Protein Accumulation in Benign Breast Tissue and Subsequent Breast Cancer Risk

    Directory of Open Access Journals (Sweden)

    Geoffrey C. Kabat

    2011-01-01

    Full Text Available Mutations in the p53 tumor suppressor gene and accumulation of its protein in breast tissue are thought to play a role in breast carcinogenesis. However, few studies have prospectively investigated the association of p53 immunopositivity and/or p53 alterations in women with benign breast disease in relation to the subsequent risk of invasive breast cancer. We carried out a case-control study nested within a large cohort of women biopsied for benign breast disease in order to address this question. After exclusions, 491 breast cancer cases and 471 controls were available for analysis. Unconditional logistic regression was used to estimate odds ratios (OR and 95% confidence intervals (95% CI. Neither p53 immunopositivity nor genetic alterations in p53 (either missense mutations or polymorphisms was associated with altered risk of subsequent breast cancer. However, the combination of both p53 immunopositivity and any p53 nucleotide change was associated with an approximate 5-fold nonsignificant increase in risk (adjusted OR 4.79, 95% CI 0.28–82.31 but the confidence intervals were extremely wide. Our findings raise the possibility that the combination of p53 protein accumulation and the presence of genetic alterations may identify a group at increased risk of breast cancer.

  19. p53 isoform profiling in glioblastoma and injured brain.

    Science.gov (United States)

    Takahashi, R; Giannini, C; Sarkaria, J N; Schroeder, M; Rogers, J; Mastroeni, D; Scrable, H

    2013-06-27

    The tumor suppressor p53 has been found to be the most commonly mutated gene in human cancers; however, the frequency of p53 mutations varies from 10 to 70% across different cancer types. This variability can partly be explained by inactivating mechanisms aside from direct genomic polymorphisms. The p53 gene encodes 12 isoforms, some of which can modulate full-length p53 activity in cancer. In this study, we characterized p53 isoform expression patterns in glioblastoma, gliosis, non-tumor brain and neural progenitor cells by SDS-PAGE, immunoblot, mass spectrometry and reverse transcription-PCR. We found that the most consistently expressed isoform in glioblastoma, Δ40p53, was uniquely expressed in regenerative processes, such as those involving neural progenitor cells and gliosis compared with tumor samples. Isoform profiling of glioblastoma tissues revealed the presence of both Δ40p53 and full-length p53, neither of which were detected in non-tumor cerebral cortex. Upon xenograft propagation of tumors, p53 levels increased. The variability of overall p53 expression and relative levels of isoforms suggest fluctuations in subpopulations of cells with greater or lesser capacity for proliferation, which can change as the tumor evolves under different growth conditions.

  20. Targeting the p53 Pathway in Ewing Sarcoma

    Directory of Open Access Journals (Sweden)

    Paul M. Neilsen

    2011-01-01

    Full Text Available The p53 tumour suppressor plays a pivotal role in the prevention of oncogenic transformation. Cancers frequently evade the potent antitumour surveillance mechanisms of p53 through mutation of the TP53 gene, with approximately 50% of all human malignancies expressing dysfunctional, mutated p53 proteins. Interestingly, genetic lesions in the TP53 gene are only observed in 10% of Ewing Sarcomas, with the majority of these sarcomas expressing a functional wild-type p53. In addition, the p53 downstream signaling pathways and DNA-damage cell cycle checkpoints remain functionally intact in these sarcomas. This paper summarizes recent insights into the functional capabilities and regulation of p53 in Ewing Sarcoma, with a particular focus on the cross-talk between p53 and the EWS-FLI1 gene rearrangement frequently associated with this disease. The development of several activators of p53 is discussed, with recent evidence demonstrating the potential of small molecule p53 activators as a promising systemic therapeutic approach for the treatment of Ewing Sarcomas with wild-type p53.

  1. Protective role of p53 in acetaminophen hepatotoxicity.

    Science.gov (United States)

    Huo, Yazhen; Yin, Shutao; Yan, Mingzhu; Win, Sanda; Aung Than, Tin; Aghajan, Mariam; Hu, Hongbo; Kaplowitz, Neil

    2017-02-11

    p53 is a tumor suppressor with a pro-death role in many conditions. However, in some contexts, evidence supports a pro-survival function. p53 has been shown to be activated in acetaminophen (APAP) toxicity but the impact of this on toxicity is uncertain. In the present study, we have found that p53 plays a protective role in APAP-induced liver injury. We inhibited p53 using three different approaches in mice, pifithrin-α (PFTα), knockdown of p53 expression with antisense oligonucleotide, and p53 knockout. Mice were treated with APAP (300mg/kg) i.p. and after 24h in all three conditions, the liver injury was more severe as reflected in higher ALT levels and great area of necrosis in histology of the liver. Conversely, a p53 activator, nutlin-3a, decreased the liver injury induced by APAP. In the p53 inhibition models, enhanced sustained JNK activation was seen in the early time course, while the JNK was suppressed with the p53 activator. In conclusion, p53 plays a novel protective role in APAP induced liver injury through inhibiting the activation of JNK, a key mediator in APAP-induced oxidative stress.

  2. 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.

  3. 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

  4. p53 DNA Binding Cooperativity Is Essential for Apoptosis and Tumor Suppression In Vivo

    Directory of Open Access Journals (Sweden)

    Oleg Timofeev

    2013-05-01

    Full Text Available Four molecules of the tumor suppressor p53 assemble to cooperatively bind proapoptotic target genes. The structural basis for cooperativity consists of interactions between adjacent DNA binding domains. Mutations at the interaction interface that compromise cooperativity were identified in cancer patients, suggesting a requirement of cooperativity for tumor suppression. We report on an analysis of cooperativity mutant p53E177R mice. Apoptotic functions of p53 triggered by DNA damage and oncogenes were abolished in these mice, whereas functions in cell-cycle control, senescence, metabolism, and antioxidant defense were retained and were sufficient to suppress development of spontaneous T cell lymphoma. Cooperativity mutant mice are nevertheless highly cancer prone and susceptible to different oncogene-induced tumors. Our data underscore the relevance of DNA binding cooperativity for p53-dependent apoptosis and tumor suppression and highlight cooperativity mutations as a class of p53 mutations that result in a selective loss of apoptotic functions due to an altered quaternary structure of the p53 tetramer.

  5. The state of the p53 and retinoblastoma genes in human cervical carcinoma cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Scheffner, M.; Muenger, K.; Byrne, J.C.; Howley, P.M. (National Cancer Inst., Bethesda, MD (United States))

    1991-07-01

    Human cervical carcinoma cell lines that were either positive or negative for human papillomavirus (HPV) DNA sequences were analyzed for evidence of mutation of the p53 and retinoblastoma genes. Each of five HPV-positive cervical cancer cell lines expressed normal pRB and low levels of wild-type p53 proteins, which are presumed to be altered in function as a consequence of association with HPV E7 and E6 oncoproteins, respectively. In contrast, mutations were identified in the p53 and RB genes expressed in the C-33A and HT-3 cervical cancer cell lines, which lack HPV DNA sequences. Mutations in the p53 genes mapped to codon 273 and codon 245 in the C33-A and HT-3 cell lines, respectively, located in the highly conserved regions of p53, where mutations appear in a variety of human cancers. Mutations in RB occurred at splice junctions, resulting in in-frame deletions, affecting exons 13 and 20 in the HT-3 and C-33A cell lines, respectively. These mutations resulted in aberrant proteins that were not phosphorylated and were unable to complex with the adenovirus E1A oncoprotein. These results support the hypothesis that the inactivation of the normal functions of the tumor-suppressor proteins pRB and p53 are important steps in human cervical carcinogenesis, either by mutation or from complex formation with the HPV E6 and E7 oncoproteins.

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

    Science.gov (United States)

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

    2004-02-01

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

  7. On p53 revival using system oriented drug dosage design.

    Science.gov (United States)

    Haseeb, Muhammad; Azam, Shumaila; Bhatti, A I; Azam, Rizwan; Ullah, Mukhtar; Fazal, Sahar

    2017-02-21

    We propose a new paradigm in the drug design for the revival of the p53 pathway in cancer cells. It is shown that the current strategy of using small molecule based Mdm2 inhibitors is not enough to adequately revive p53 in cancerous cells, especially when it comes to the extracting pulsating behavior of p53. This fact has come to notice when a novel method for the drug dosage design is introduced using system oriented concepts. As a test case, small molecule drug Mdm2 repressor Nutlin 3a is considered. The proposed method determines the dose of Nutlin to revive p53 pathway functionality. For this purpose, PBK dynamics of Nutlin have also been integrated with p53 pathway model. The p53 pathway is the focus of researchers for the last thirty years for its pivotal role as a frontline cancer suppressant protein due to its effect on cell cycle checkpoints and cell apoptosis in response to a DNA strand break. That is the reason for finding p53 being absent in more than 50% of tumor cancers. Various drugs have been proposed to revive p53 in cancer cells. Small molecule based drugs are at the foremost and are the subject of advanced clinical trials. The dosage design of these drugs is an important issue. We use control systems concepts to develop the drug dosage so that the cancer cells can be treated in appropriate time. We investigate by using a computational model how p53 protein responds to drug Nutlin 3a, an agent that interferes with the MDM2-mediated p53 regulation. The proposed integrated model describes in some detail the regulation network of p53 including the negative feedback loop mediated by MDM2 and the positive feedback loop mediated by Mdm2 mRNA as well as the reversible represses of MDM2 caused by Nutlin. The reported PBK dynamics of Nutlin 3a are also incorporated to see the full effect. It has been reported that p53 response to stresses in two ways. Either it has a sustained (constant) p53 response, or there are oscillations in p53 concentration. The

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

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    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.

  9. P53 tumor suppression network in cancer epigenetics.

    Science.gov (United States)

    Mishra, Alok; Brat, Daniel J; Verma, Mukesh

    2015-01-01

    The tumor suppressor p53 is one of the most complex and widely studied genes in cancer biology. In spite of the vast on literature the transcriptional regulation of p53, aspects of its especially epigenetic regulation are not completely understood. This chapter presents a concise overview of p53-related epigenetic events involved in oncogenesis and tumor suppression. We limit the scope to epigenetic modifications of the p53 promoter per se as well as its well-established downstream targets. The indirect role of p53 affecting the epigenetic machinery of cancer cells via specific proteins and transcription factors is discussed. Current concepts of p53-related cancer epigenetics offer myriad avenues for cancer therapies. Challenges in the field are also discussed.

  10. Positive effect of Mdm2 on p53 expression explains excitability of p53 in response to DNA damage.

    Science.gov (United States)

    Eliaš, Ján

    2017-04-07

    Most of the existing biological models consider Mdm2 as a dominant negative regulator of p53 appearing in several negative feedback loops. However, in addition to targeting p53 for degradation, Mdm2 in tight cooperation with MdmX can control expression levels of p53 through enhanced induction of p53 synthesis in response to DNA damage. Whilst ATM-dependent phosphorylation of p53 is not observed to be important in this enhanced synthesis, ATM-dependent phosphorylation of Mdm2 (as well as MdmX) is essential for its dual role, which is accompanied with widely oscillating p53. In the light of these new observations we formulate a novel molecular mechanism which, in silico, is capable of triggering p53 oscillations. The mechanism that is based on Mdm2's dual regulation of p53 can provide mechanistic insights into an excitability of the p53 network, thus it contributes to understanding of variability of p53 dynamics in response to single and double strand breaks.

  11. HDAC6 deacetylates p53 at lysines 381/382 and differentially coordinates p53-induced apoptosis.

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    Ryu, Hyun-Wook; Shin, Dong-Hee; Lee, Dong Hoon; Choi, Junjeong; Han, Gyoonhee; Lee, Kang Young; Kwon, So Hee

    2017-04-10

    HDAC6-selective inhibitors represent promising new cancer therapeutic agents, but their precise mechanisms of action are not well understood. In particular, p53's role in HDAC6 inhibitor-induced effects has not been fully elucidated. In this study, we show that an HDAC6-selective inhibitor, A452, increased wild-type p53 levels by destabilizing MDM2, but decreased mutant p53 by inducing MDM2 and inhibiting Hsp90-mutant p53 complex formation. Interestingly, HDAC6 levels inversely correlated with p53 acetylation at lysines 381/382 associated with p53 functional activation. A452 blocked HDAC6 nuclear localization, resulting in increased levels of acetylated p53 at Lys381/382. HDAC6 bound to the C-terminal region of p53 via its deacetylase domain. A452 disrupted the HDAC6-Hsp90 chaperone machinery via Hsp90 acetylation and degradation. Furthermore, it chemosensitized cancer cells to the Hsp90 inhibitor 17-AAG. Overall, silencing of HDAC6 showed similar effects. These findings suggest that the anticancer action of HDAC6 inhibitors requires p53 and Hsp90 and targeting of HDAC6 may represent a new therapeutic strategy for cancers regardless of p53's mutation status.

  12. Analysis of p53- immunoreactivity in astrocytic brain tumors

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    Shinkarenko T.V.

    2016-12-01

    Full Text Available P53 is an antioncogene with the frequently occured mutations in human tumor cells, leading to corresponding protein overexpression which can be detected by immunohistochemistry. Researches dedicated to the investigation of possibilities of using this technique gave controversial results. The authors investigated features of p53 protein expression in astrocytic brain tumors with different degrees of malignancy. Analyzed the relationship of the expression level of p53 by tumor cells with clinical parameters and Ki-67 proliferation index (PI as well. Tissues were collected from 52 cases with diagnosed astrocytic brain tumors. The sections were immunohistochemically stained with p53 and Ki-67. For each marker, 1000 tumor cells were counted and the ratio of positive tumor cells was calculated using software package ImageJ 1,47v. In normal brain tissue p53- expression was not identified. p53-immunoreactive tumor cells were detected in 25% (1/4 pilocytic astrocytomas, 33.3% (2/6 of diffuse astrocytomas, 53.8% (7/13 anaplastic astrocytomas, 58.6% (17/29 glioblastomas. A high proportion of p53-immunoreactive cells (> 30% was observed only in glioblastomas. The level of p53-imunoreactivity was not related to the age, gender and Grade WHO (p> 0,05. Spearman correlation coefficient between the relative quantity of ki-67- and p53-immunoreactive nuclei showed weak direct correlation (0.023, but the one was not statistically significant (p> 0,05. The level of p53-imunoreactivity is not dependent from age and sex of patients, Grade (WHO and proliferative activity (p>0,05 but the high level of p53-immunoreactive cells (>30% is found in glioblastoma specimens only, that may be due to the accumulation of mutations in DNA of tumor cells. There is insignificant weak relationship between relative quantities of ki-67- and p53-immunoreactive tumor cells (p>0,05.

  13. "Super p53" mice display retinal astroglial changes.

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    Juan J Salazar

    Full Text Available Tumour-suppressor genes, such as the p53 gene, produce proteins that inhibit cell division under adverse conditions, as in the case of DNA damage, radiation, hypoxia, or oxidative stress (OS. The p53 gene can arrest proliferation and trigger death by apoptosis subsequent to several factors. In astrocytes, p53 promotes cell-cycle arrest and is involved in oxidative stress-mediated astrocyte cell death. Increasingly, astrocytic p53 is proving fundamental in orchestrating neurodegenerative disease pathogenesis. In terms of ocular disease, p53 may play a role in hypoxia due to ischaemia and may be involved in the retinal response to oxidative stress (OS. We studied the influence of the p53 gene in the structural and quantitative characteristics of astrocytes in the retina. Adult mice of the C57BL/6 strain (12 months old were distributed into two groups: 1 mice with two extra copies of p53 ("super p53"; n = 6 and 2 wild-type p53 age-matched control, as the control group (WT; n = 6. Retinas from each group were immunohistochemically processed to locate the glial fibrillary acidic protein (GFAP. GFAP+ astrocytes were manually counted and the mean area occupied for one astrocyte was quantified. Retinal-astrocyte distribution followed established patterns; however, morphological changes were seen through the retinas in relation to p53 availability. The mean GFAP+ area occupied by one astrocyte in "super p53" eyes was significantly higher (p<0.05; Student's t-test than in the WT. In addition, astroglial density was significantly higher in the "super p53" retinas than in the WT ones, both in the whole-retina (p<0,01 Student's t-test and in the intermediate and peripheral concentric areas of the retina (p<0.05 Student's t-test. This fact might improve the resistance of the retinal cells against OS and its downstream signalling pathways.

  14. DDX3 regulates DNA damage-induced apoptosis and p53 stabilization.

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    Sun, Mianen; Zhou, Tong; Jonasch, Eric; Jope, Richard S

    2013-06-01

    The DEAD box protein family member DDX3 was previously identified as an inhibitor of death receptor-mediated extrinsic apoptotic signaling. However, there had been no studies of the role of DDX3 in regulating the other major type of apoptosis, intrinsic apoptotic signaling, which was examined here. Intrinsic apoptosis was induced in MCF-7 cells by treatment with staurosporine, a general kinase inhibitor, thapsigargin, which induces endoplasmic reticulum (ER) stress, and camptothecin, which causes DNA damage. Each of these treatments caused time-dependent activation of caspase-7, the predominant executioner caspase in these cells. Depletion of DDX3 using shRNA did not alter apoptotic responses to staurosporine or thapsigargin. However, caspase-7 activation induced by camptothecin was regulated by DDX3 in a manner dependent on the functional status of p53. Depletion of DDX3 abrogated camptothecin-induced caspase-7 activation in MCF-7 cells expressing functional wild-type p53, but oppositely potentiated camptothecin-mediated caspase activation in cells expressing mutant or non-functional p53, which was accompanied by increased activation of the extrinsic apoptotic signaling initiator caspase-8. In MCF-7 cells, depletion of DDX3 reduced by more than 50% camptothecin-induced p53 accumulation, and this effect was blocked by inhibition of the proteasome with MG132, indicating that DDX3 regulates p53 not at expression level but rather its stabilization after DNA damage. Co-immunoprecipitation experiments demonstrated that DDX3 associates with p53, and overexpression of DDX3 was sufficient to double the accumulation of p53 in the nucleus after DNA damage. Thus, DDX3 associates with p53, increases p53 accumulation, and positively regulates camptothecin-induced apoptotic signaling in cells expressing functional wild-type p53, whereas in cells expressing mutant or non-functional p53 DDX3 inhibits activation of the extrinsic apoptotic pathway to reduce caspase activation. These

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

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    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.

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

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    Janine G. Einspahr

    1999-11-01

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

  17. Structural visualization of the p53/RNA polymerase II assembly.

    Science.gov (United States)

    Singh, Sameer K; Qiao, Zhen; Song, Lihua; Jani, Vijay; Rice, William; Eng, Edward; Coleman, Robert A; Liu, Wei-Li

    2016-11-15

    The master tumor suppressor p53 activates transcription in response to various cellular stresses in part by facilitating recruitment of the transcription machinery to DNA. Recent studies have documented a direct yet poorly characterized interaction between p53 and RNA polymerase II (Pol II). Therefore, we dissected the human p53/Pol II interaction via single-particle cryo-electron microscopy, structural docking, and biochemical analyses. This study reveals that p53 binds Pol II via the Rpb1 and Rpb2 subunits, bridging the DNA-binding cleft of Pol II proximal to the upstream DNA entry site. In addition, the key DNA-binding surface of p53, frequently disrupted in various cancers, remains exposed within the assembly. Furthermore, the p53/Pol II cocomplex displays a closed conformation as defined by the position of the Pol II clamp domain. Notably, the interaction of p53 and Pol II leads to increased Pol II elongation activity. These findings indicate that p53 may structurally regulate DNA-binding functions of Pol II via the clamp domain, thereby providing insights into p53-regulated Pol II transcription.

  18. Recognition of Local DNA Structures by p53 Protein.

    Science.gov (United States)

    Brázda, Václav; Coufal, Jan

    2017-02-10

    p53 plays critical roles in regulating cell cycle, apoptosis, senescence and metabolism and is commonly mutated in human cancer. These roles are achieved by interaction with other proteins, but particularly by interaction with DNA. As a transcription factor, p53 is well known to bind consensus target sequences in linear B-DNA. Recent findings indicate that p53 binds with higher affinity to target sequences that form cruciform DNA structure. Moreover, p53 binds very tightly to non-B DNA structures and local DNA structures are increasingly recognized to influence the activity of wild-type and mutant p53. Apart from cruciform structures, p53 binds to quadruplex DNA, triplex DNA, DNA loops, bulged DNA and hemicatenane DNA. In this review, we describe local DNA structures and summarize information about interactions of p53 with these structural DNA motifs. These recent data provide important insights into the complexity of the p53 pathway and the functional consequences of wild-type and mutant p53 activation in normal and tumor cells.

  19. The Mechanism of p53 Rescue by SUSP4.

    Science.gov (United States)

    Kim, Do-Hyoung; Lee, Chewook; Lee, Si-Hyung; Kim, Kyung-Tae; Han, Joan J; Cha, Eun-Ji; Lim, Ji-Eun; Cho, Ye-Jin; Hong, Seung-Hee; Han, Kyou-Hoon

    2017-01-24

    p53 is an important tumor-suppressor protein deactivation of which by mdm2 results in cancers. A SUMO-specific protease 4 (SUSP4) was shown to rescue p53 from mdm2-mediated deactivation, but the mechanism is unknown. The discovery by NMR spectroscopy of a "p53 rescue motif" in SUSP4 that disrupts p53-mdm2 binding is presented. This 29-residue motif is pre-populated with two transient helices connected by a hydrophobic linker. The helix at the C-terminus binds to the well-known p53-binding pocket in mdm2 whereas the N-terminal helix serves as an affinity enhancer. The hydrophobic linker binds to a previously unidentified hydrophobic crevice in mdm2. Overall, SUSP4 appears to use two synergizing modules, the p53 rescue motif described here and a globular-structured SUMO-binding catalytic domain, to stabilize p53. A p53 rescue motif peptide exhibits an anti-tumor activity in cancer cell lines expressing wild-type p53. A pre-structures motif in the intrinsically disordered proteins is thus important for target recognition.

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

    Science.gov (United States)

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

    2017-02-07

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

  1. 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.

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

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    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.

  3. Effects of p53 knockout on ochratoxin A-induced genotoxicity in p53-deficient gpt delta mice.

    Science.gov (United States)

    Hibi, Daisuke; Kijima, Aki; Suzuki, Yuta; Ishii, Yuji; Jin, Meilan; Sugita-Konishi, Yoshiko; Yanai, Tokuma; Nishikawa, Akiyoshi; Umemura, Takashi

    2013-02-01

    Ochratoxin A (OTA) is a mycotoxin produced by fungal species and is carcinogenic targeting the S3 segment of the renal proximal tubules in rodents. We previously reported that exposure of gpt delta rats to OTA induced both mutations in the red/gam gene (Spi(-)), suggesting large deletion mutations, and fluctuations in genes transcribed by p53 in the kidneys, which were associated with DNA double-strand break (DSB) repair, particularly homologous recombination (HR) repair. In the present study, to investigate the effects of p53 knockout on OTA-induced mutagenicity, apoptosis, and karyomegaly in renal tubular cells, p53-proficient and p53-deficient gpt delta mice were given 1 and 5mg/kg of OTA for 4 weeks. Significant increases in Spi(-) mutant frequencies (MFs) were observed in the kidneys of p53-deficient gpt delta mice given 5 mg/kg of OTA, but not in the kidneys of p53-proficient gpt delta mice given the same dose. There were no changes in gpt MFs in both genotypes of mice treated with OTA. Western blotting analysis demonstrated that p53 protein levels in the kidneys of p53-proficient mice given OTA were significantly increased compared with the control. Incidences of apoptosis and karyomegaly in not only the outer stripe of outer medulla but also the cortex were significantly higher in p53-deficient at 5mg/kg than in p53-proficient gpt delta mice at same dose, which had no change in the cortex, the inner stripe of outer stripe, and the inner medulla. Given that p53 regulates HR repair in DSBs, these results suggest that OTA may promote large deletion mutations in the process of HR repair for DSBs. Additionally, the lower incidence of karyomegaly and apoptosis found in the p53-proficient gpt delta mice suggests that these phenomena may arise from OTA-induced DNA damage.

  4. p53 Amino-terminus region (1-125 stabilizes and restores heat denatured p53 wild phenotype.

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    Anuj Kumar Sharma

    Full Text Available BACKGROUND: The intrinsically disordered N-ter domain (NTD of p53 encompasses approximately hundred amino acids that contain a transactivation domain (1-73 and a proline-rich domain (64-92 and is responsible for transactivation function and apoptosis. It also possesses an auto-inhibitory function as its removal results in remarkable reduction in dissociation of p53 from DNA. PRINCIPAL FINDINGS/METHODOLOGY: In this report, we have discovered that p53-NTD spanning amino acid residues 1-125 (NTD125 interacted with WT p53 and stabilized its wild type conformation under physiological and elevated temperatures, both in vitro and in cellular systems. NTD125 prevented irreversible thermal aggregation of heat denatured p53, enhanced p21-5'-DBS binding and further restored DBS binding activity of heat-denatured p53, in vitro, in a dose-dependent manner. In vivo ELISA and immunoprecipitation analysis of NTD125-transfected cells revealed that NTD125 shifted equilibrium from p53 mutant to wild type under heat stress conditions. Further, NTD125 initiated nuclear translocation of cytoplasmic p53 in transcriptionally active state in order to activate p53 downstream genes such as p21, Bax, PUMA, Noxa and SUMO. CONCLUSION/SIGNIFICANCE: Here, we showed that a novel chaperone-like activity resides in p53-N-ter region. This study might have significance in understanding the role of p53-NTD in p53 stabilization, conformational activation and apoptosis under heat-stress conditions.

  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. The structure formed by inverted repeats in p53 response elements determines the transactivation activity of p53 protein.

    Science.gov (United States)

    Brázda, Václav; Čechová, Jana; Battistin, Michele; Coufal, Jan; Jagelská, Eva B; Raimondi, Ivan; Inga, Alberto

    2017-01-29

    The TP53 gene is the most frequently mutated gene in human cancer and p53 protein plays a crucial role in gene expression and cancer protection. Its role is manifested by interactions with other proteins and DNA. p53 is a transcription factor that binds to DNA response elements (REs). Due to the palindromic nature of the consensus binding site, several p53-REs have the potential to form cruciform structures. However, the influence of cruciform formation on the activity of p53-REs has not been evaluated. Therefore, we prepared sets of p53-REs with identical theoretical binding affinity in their linear state, but different probabilities to form extra helical structures, for in vitro and in vivo analyses. Then we evaluated the presence of cruciform structures when inserted into plasmid DNA and employed a yeast-based assay to measure transactivation potential of these p53-REs cloned at a chromosomal locus in isogenic strains. We show that transactivation in vivo correlated more with relative propensity of an RE to form cruciforms than to its predicted in vitro DNA binding affinity for wild type p53. Structural features of p53-REs could therefore be an important determinant of p53 transactivation function.

  7. Long Noncoding RNA MEG3 Interacts with p53 Protein and Regulates Partial p53 Target Genes in Hepatoma Cells.

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    Juanjuan Zhu

    Full Text Available Maternally Expressed Gene 3 (MEG3 encodes a lncRNA which is suggested to function as a tumor suppressor. Previous studies suggested that MEG3 functioned through activation of p53, however, the functional properties of MEG3 remain obscure and their relevance to human diseases is under continuous investigation. Here, we try to illuminate the relationship of MEG3 and p53, and the consequence in hepatoma cells. We find that transfection of expression construct of MEG3 enhances stability and transcriptional activity of p53. Deletion analysis of MEG3 confirms that full length and intact structure of MEG3 are critical for it to activate p53-mediated transactivation. Interestingly, our results demonstrate for the first time that MEG3 can interact with p53 DNA binding domain and various p53 target genes are deregulated after overexpression of MEG3 in hepatoma cells. Furthermore, results of qRT-PCR have shown that MEG3 RNA is lost or reduced in the majority of HCC samples compared with adjacent non-tumorous samples. Ectopic expression of MEG3 in hepatoma cells significantly inhibits proliferation and induces apoptosis. In conclusion, our data demonstrates that MEG3 functions as a tumor suppressor in hepatoma cells through interacting with p53 protein to activate p53-mediated transcriptional activity and influence the expression of partial p53 target genes.

  8. 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...

  9. A platform for interrogating cancer-associated p53 alleles.

    Science.gov (United States)

    D'Brot, A; Kurtz, P; Regan, E; Jakubowski, B; Abrams, J M

    2017-01-12

    p53 is the most frequently mutated gene in human cancer. Compelling evidence argues that full transformation involves loss of growth suppression encoded by wild-type p53 together with poorly understood oncogenic activity encoded by missense mutations. Furthermore, distinguishing disease alleles from natural polymorphisms is an important clinical challenge. To interrogate the genetic activity of human p53 variants, we leveraged the Drosophila model as an in vivo platform. We engineered strains that replace the fly p53 gene with human alleles, producing a collection of stocks that are, in effect, 'humanized' for p53 variants. Like the fly counterpart, human p53 transcriptionally activated a biosensor and induced apoptosis after DNA damage. However, all humanized strains representing common alleles found in cancer patients failed to complement in these assays. Surprisingly, stimulus-dependent activation of hp53 occurred without stabilization, demonstrating that these two processes can be uncoupled. Like its fly counterpart, hp53 formed prominent nuclear foci in germline cells but cancer-associated p53 variants did not. Moreover, these same mutant alleles disrupted hp53 foci and inhibited biosensor activity, suggesting that these properties are functionally linked. Together these findings establish a functional platform for interrogating human p53 alleles and suggest that simple phenotypes could be used to stratify disease variants.

  10. p53 and mitochondrial dysfunction: novel insight of neurodegenerative diseases.

    Science.gov (United States)

    Dai, Chun-Qiu; Luo, Ting-Ting; Luo, Shi-Cheng; Wang, Jia-Qi; Wang, Sheng-Ming; Bai, Yun-Hu; Yang, Yan-Ling; Wang, Ya-Yun

    2016-08-01

    Mitochondria are organelles responsible for vital cell functions. p53 is a transcription factor that regulates the DNA stability and cell growth normality. Recent studies revealed that p53 can influence mitochondrial function changing from normal condition to abnormal condition under different stress levels. In normal state, p53 can maintain mitochondrial respiration through transactivation of SCO2. When stress stimuli presents, SCO2 overexpresses and leads to ROS generation. ROS promotes p53 inducing MALM (Mieap-induced accumulation of lysosome-like organelles within mitochondria) to repair dysfunctional mitochondria and MIV (Mieap-induced vacuole) to accomplish damaged mitochondria degradation. If stress or damage is irreversible, p53 will translocate to mitochondria, leading into apoptosis or necrosis. Neurodegenerative diseases including Parkinson's disease, Huntington's disease and Alzheimer's disease are still lack of clear explanations of mechanisms, but more studies have revealed the functional relationship between mitochondria and p53 towards the pathological development of these diseases. In this review, we discuss that p53 plays the vital role in the function of mitochondria in the aspect of pathological change metabolism. We also analyze these diseases with novel targeted treating molecules which are related to p53 and mitochondria, hoping to present novel therapies in future clinic.

  11. Negative auto-regulators trap p53 in their web.

    Science.gov (United States)

    Zhou, Xiang; Cao, Bo; Lu, Hua

    2017-01-09

    The transcriptional factor p53 activates the expression of a myriad of target genes involving a complicated signalling network, resulting in various cellular outcomes, such as growth arrest, senescence, apoptosis, and metabolic changes, and leading to consequent suppression of tumour growth and progression. Because of the profoundly adverse effect of p53 on growth and proliferation of cancer cells, several feedback mechanisms have been employed by the cells to constrain p53 activity. Two major antagonists MDM2 and MDMX (the long forms) are transcriptionally induced by p53, but in return block p53 activity, forming a negative feedback circuit and rendering chemoresistance of several cancer cells. However, they are not alone, as cancer cells also employ other proteins encoded by p53 target genes to inhibit p53 activity at transcriptional, translational, and posttranslational levels. This essay is thus composed to review a recent progress in understanding the mechanisms for how cancer cells hijack the p53 autoregulation by these proteins for their growth advantage and to discuss the clinical implications of these autoregulatory loops.

  12. Expression of P53 protein after exposure to ionizing radiation

    Science.gov (United States)

    Salazar, A. M.; Salvador, C.; Ruiz-Trejo, C.; Ostrosky, P.; Brandan, M. E.

    2001-10-01

    One of the most important tumor suppressor genes is p53 gene, which is involved in apoptotic cell death, cell differentiation and cell cycle arrest. The expression of p53 gene can be evaluated by determining the presence of P53 protein in cells using Western Blot assay with a chemiluminescent method. This technique has shown variabilities that are due to biological factors. Film developing process can influence the quality of the p53 bands obtained. We irradiated tumor cell lines and human peripheral lymphocytes with 137Cs and 60Co gamma rays to standardize irradiation conditions, to compare ionizing radiation with actinomycin D and to reduce the observed variability of P53 protein induction levels. We found that increasing radiation doses increase P53 protein induction while it decreases viability. We also conclude that ionizing radiation could serve as a positive control for Western Blot analysis of protein P53. In addition, our results show that the developing process may play an important role in the quality of P53 protein bands and data interpretation.

  13. p53 downregulates the Fanconi anaemia DNA repair pathway.

    Science.gov (United States)

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

    2016-04-01

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

  14. Expression of pRb, p53, p16 and cyclin D1 and their clinical implications in urothelial carcinoma.

    Science.gov (United States)

    Lee, Kyungji; Jung, Eun Sun; Choi, Young-Jin; Lee, Kyo Young; Lee, Ahwon

    2010-10-01

    The aim of this study was to assess immunohistochemical expression of p53, pRb, p16, and cyclin D1, alone or in combination, as prognostic indicators and to investigate their correlation with clinocopathologic features of urothelial carcinoma. Immunohistochemical staining for p53, pRb, p16, and cyclin D1 was performed on a tissue microarray from 103 patients with urothelial carcinoma who underwent radical cystectomy. Of the patient samples analyzed, 36 (35%), 61 (59%), 47 (46%) and 30 (29%) had altered expression of p53, pRb, p16, and cyclin D1, respectively. Abnormal expression of p53 and pRb correlated with depth of invasion (P=0.040 and P=0.044, respectively). Cyclin D1 expression was associated with tumor stage and recurrence (P=0.017 and P=0.036, respectively). Altered pRb was significantly correlated with overall survival (P=0.040). According to the expression pattern of pRb and p53, p53/pRb (altered/normal) had worse survival than p53/pRb (normal/altered) (P=0.022). Alteration of all markers had worse survival than all normal (P=0.029). As determined by multivariate analysis, tumor stage, lymph node metastasis and the combined expression of p53 and pRb are independent prognostic factors. In conclusion, immunohistochemical evaluation of cell cycle regulators, especially the p53/pRb combination, might be useful in planning appropriate treatment strategies.

  15. Peran Gen p53 dan Regulasi Apoptosis Pada Perkembangan Kanker, Khususnya Karsinoma Kepala dan Leher

    Directory of Open Access Journals (Sweden)

    Harmas Yazid Yusuf

    2015-10-01

    Full Text Available It is now well established that cancer is a complex genetic disease. These genetic alterations include the function of tumor supressor gene p 53 and apoptosis. The interaction between these factors have key role in cell proliferation and cell death. Functional lost of apoptotic regulation is an important thing in tumor pathogenesis as tumor will develop in rapid manner and indefinitely.

  16. Peran Gen p53 dan Regulasi Apoptosis Pada Perkembangan Kanker, Khususnya Karsinoma Kepala dan Leher

    OpenAIRE

    2015-01-01

    It is now well established that cancer is a complex genetic disease. These genetic alterations include the function of tumor supressor gene p 53 and apoptosis. The interaction between these factors have key role in cell proliferation and cell death. Functional lost of apoptotic regulation is an important thing in tumor pathogenesis as tumor will develop in rapid manner and indefinitely.

  17. p53 prevents neurodegeneration by regulating synaptic genes.

    Science.gov (United States)

    Merlo, Paola; Frost, Bess; Peng, Shouyong; Yang, Yawei J; Park, Peter J; Feany, Mel

    2014-12-16

    DNA damage has been implicated in neurodegenerative disorders, including Alzheimer's disease and other tauopathies, but the consequences of genotoxic stress to postmitotic neurons are poorly understood. Here we demonstrate that p53, a key mediator of the DNA damage response, plays a neuroprotective role in a Drosophila model of tauopathy. Further, through a whole-genome ChIP-chip analysis, we identify genes controlled by p53 in postmitotic neurons. We genetically validate a specific pathway, synaptic function, in p53-mediated neuroprotection. We then demonstrate that the control of synaptic genes by p53 is conserved in mammals. Collectively, our results implicate synaptic function as a central target in p53-dependent protection from neurodegeneration.

  18. p53 immunoreactivity is uncommon in primary cutaneous lymphoma.

    Science.gov (United States)

    McGregor, J M; Dublin, E A; Levison, D A; MacDonald, D M; Smith, N P; Whittaker, S

    1995-03-01

    p53 gene mutation appears to play an important role in the development of systemic lymphoma, and may be associated with tumour progression. Its role in cutaneous lymphoma is currently unknown. We examined p53 expression in 55 biopsies of cutaneous lymphoma, including patch-, plaque- and tumour-stage mycosis fungoides (MF), T- and B-cell lymphoma and lymphomatoid papulosis. Strong, homogeneous p53 expression, thought to correlate most closely with p53 gene mutation, was seen in only three cases; in a plaque and tumour from a patient with tumour-stage MF, in plaque-stage MF in a patient without tumours, and in one case of CD30+ large-cell anaplastic lymphoma. These data suggest that p53 gene mutation is not a critical step in the development of the majority of primary cutaneous lymphomas.

  19. The p53 Codon 72 Polymorphism Modifies the Cellular Response to Inflammatory Challenge in the Liver.

    Science.gov (United States)

    Leu, Julia I-Ju; Murphy, Maureen E; George, Donna L

    2013-01-01

    The p53 protein is a critical stress-response mediator and signal coordinator in cellular metabolism and environmental exposure to deleterious agents. In human populations, the p53 gene contains a common single nucleotide polymorphism (SNP) affecting codon 72 that determines whether a proline (P72) or an arginine (R72) is present at this amino acid position of the polypeptide. Previous studies carried out using human populations, mouse models, and cell culture analyses have provided evidence that this amino acid difference can alter p53 functional activities, and potentially also can affect clinical presentation of disease. The clinical presentation associated with many forms of liver disease is variable, but few of the responsible underlying genetic factors or molecular pathways have been identified. The aim of the present study was to investigate whether the p53 codon 72 polymorphism influences the cellular response to hepatic stresses. A humanized p53 knock-in (Hupki) mouse model was used to address this issue. Mice expressing either the P72 or R72 normal variation of p53 were given an acute-, intermittent- or a chronic challenge, associated with exposure to lipopolysaccharide, D-galactosamine, or a high-fat diet. The results reveal that the livers of the P72 and R72 mice exhibit notable differences in inflammatory and apoptotic response to these distinct forms of stress. Interestingly the influence of this polymorphism on the response to stress is context dependent, with P72 showing increased response to liver toxins (lipopolysaccharide and D-galactosamine), but R72 showing increased response to metabolic stress (high fat diet). When taken together, these data point to the p53 codon 72 polymorphism as an important molecular mediator of events contributing to hepatic inflammation and metabolic homeostasis.

  20. The p53 inhibitor MDM2 facilitates Sonic Hedgehog-mediated tumorigenesis and influences cerebellar foliation.

    Directory of Open Access Journals (Sweden)

    Reem Malek

    Full Text Available Disruption of cerebellar granular neuronal precursor (GNP maturation can result in defects in motor coordination and learning, or in medulloblastoma, the most common childhood brain tumor. The Sonic Hedgehog (Shh pathway is important for GNP proliferation; however, the factors regulating the extent and timing of GNP proliferation, as well as GNP differentiation and migration are poorly understood. The p53 tumor suppressor has been shown to negatively regulate the activity of the Shh effector, Gli1, in neural stem cells; however, the contribution of p53 to the regulation of Shh signaling in GNPs during cerebellar development has not been determined. Here, we exploited a hypomorphic allele of Mdm2 (Mdm2(puro, which encodes a critical negative regulator of p53, to alter the level of wild-type MDM2 and p53 in vivo. We report that mice with reduced levels of MDM2 and increased levels of p53 have small cerebella with shortened folia, reminiscent of deficient Shh signaling. Indeed, Shh signaling in Mdm2-deficient GNPs is attenuated, concomitant with decreased expression of the Shh transducers, Gli1 and Gli2. We also find that Shh stimulation of GNPs promotes MDM2 accumulation and enhances phosphorylation at serine 166, a modification known to increase MDM2-p53 binding. Significantly, loss of MDM2 in Ptch1(+/- mice, a model for Shh-mediated human medulloblastoma, impedes cerebellar tumorigenesis. Together, these results place MDM2 at a major nexus between the p53 and Shh signaling pathways in GNPs, with key roles in cerebellar development, GNP survival, cerebellar foliation, and MB tumorigenesis.

  1. 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

    PURPOSE: Langerhans cell histiocytosis (LCH) is a rare pediatric and adult disease causing skin rashes, osteolytic bone lesions, tumorous growth in various organs, and in some patients, organ dysfunction. The cause of the disease is obscure, and it is not yet understood why some patients develop...... 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, Ingrit [Institut fuer Angewandte Biowissenschaften, Abteilung Lebensmittelchemie und Toxikologie, Karlsruher Institut fuer Technologie (KIT), 76131 Karlsruhe (Germany); Fachgebiet Lebensmittelchemie und Toxikologie, Institut fuer Lebensmitteltechnologie und Lebensmittelchemie, Technische Universitaet Berlin, 13355 Berlin (Germany); Faculty for Pharmacy and Pharmaceutical Sciences, University of Alberta, 3126 Dentistry/Pharmacy Centre, Edmonton, Alberta, Canada T6G 2N8 (Canada); Koenig, Charlotte; Richter, Constanze [Fachgebiet Lebensmittelchemie und Toxikologie, Institut fuer Lebensmitteltechnologie und Lebensmittelchemie, Technische Universitaet Berlin, 13355 Berlin (Germany); Jahnke, Gunnar [Institut fuer Angewandte Biowissenschaften, Abteilung Lebensmittelchemie und Toxikologie, Karlsruher Institut fuer Technologie (KIT), 76131 Karlsruhe (Germany); Fachgebiet Lebensmittelchemie und Toxikologie, Institut fuer Lebensmitteltechnologie und Lebensmittelchemie, Technische Universitaet Berlin, 13355 Berlin (Germany); Hartwig, Andrea, E-mail: andrea.hartwig@kit.edu [Institut fuer Angewandte Biowissenschaften, Abteilung Lebensmittelchemie und Toxikologie, Karlsruher Institut fuer Technologie (KIT), 76131 Karlsruhe (Germany); Fachgebiet Lebensmittelchemie und Toxikologie, Institut fuer Lebensmitteltechnologie und Lebensmittelchemie, Technische Universitaet Berlin, 13355 Berlin (Germany)

    2012-08-01

    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 Pol{beta}. In studies in HCT116 p53{sup -/-} 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{sup +/+} 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{sup +/+} cells. In summary, p53 indeed affects the BER pathway directly and indirectly in response to cadmium treatment.

  3. Loss of p53 expression is accompanied by upregulation of beta-catenin in meningiomas: a concomitant reciprocal expression.

    Science.gov (United States)

    Pećina-Šlaus, Nives; Kafka, Anja; Vladušić, Tomislav; Tomas, Davor; Logara, Monika; Skoko, Josip; Hrašćan, Reno

    2016-04-01

    Crosstalk between Wnt and p53 signalling pathways in cancer has long been suggested. Therefore in this study we have investigated the involvement of these pathways in meningiomas by analysing their main effector molecules, beta-catenin and p53. Cellular expression of p53 and beta-catenin proteins and genetic changes in TP53 were analysed by immunohistochemistry, PCR/RFLP and direct sequencing of TP53 exon 4. All the findings were analysed statistically. Our analysis showed that 47.5% of the 59 meningiomas demonstrated loss of expression of p53 protein. Moderate and strong p53 expression in the nuclei was observed in 8.5% and 6.8% of meningiomas respectively. Gross deletion of TP53 gene was observed in one meningioma, but nucleotide alterations were observed in 35.7% of meningiomas. In contrast, beta-catenin, the main Wnt signalling molecule, was upregulated in 71.2%, while strong expression was observed in 28.8% of meningiomas. The concomitant expressions of p53 and beta-catenin were investigated in the same patients. In the analysed meningiomas, the levels of the two proteins were significantly negatively correlated (P = 0.002). This indicates that meningiomas with lost p53 upregulate beta-catenin and activate Wnt signalling. Besides showing the reciprocal relationship between proteins, we also showed that the expression of p53 was significantly (P = 0.021) associated with higher meningioma grades (II and III), while beta-catenin upregulation was not associated with malignancy grades. Additionally, women exhibited significantly higher values of p53 loss when compared to males (P = 0.005). Our findings provide novel information about p53 involvement in meningeal brain tumours and reveal the complex relationship between Wnt and p53 signalling, they suggest an important role for beta-catenin in these tumours.

  4. A p53-bound enhancer region controls a long intergenic noncoding RNA required for p53 stress response

    NARCIS (Netherlands)

    Melo, C A; Léveillé, N; Rooijers, K; Wijchers, P J; Geeven, G; Tal, A; Melo, S A; de Laat, W; Agami, R

    2016-01-01

    Genome-wide chromatin studies identified the tumor suppressor p53 as both a promoter and an enhancer-binding transcription factor. As an enhancer factor, p53 can induce local production of enhancer RNAs, as well as transcriptional activation of distal neighboring genes. Beyond the regulation of prot

  5. The combined status of ATM and p53 link tumor development with therapeutic response

    DEFF Research Database (Denmark)

    Jiang, Hai; Reinhardt, H Christian; Bartkova, Jirina;

    2009-01-01

    commonly used by tumors to bypass early neoplastic checkpoints ultimately determine chemotherapeutic response and generate tumor-specific vulnerabilities that can be exploited with targeted therapies. Specifically, evaluation of the combined status of ATM and p53, two commonly mutated tumor suppressor...... genes, can help to predict the clinical response to genotoxic chemotherapies. We show that in p53-deficient settings, suppression of ATM dramatically sensitizes tumors to DNA-damaging chemotherapy, whereas, conversely, in the presence of functional p53, suppression of ATM or its downstream target Chk2......While the contribution of specific tumor suppressor networks to cancer development has been the subject of considerable recent study, it remains unclear how alterations in these networks are integrated to influence the response of tumors to anti-cancer treatments. Here, we show that mechanisms...

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

    Directory of Open Access Journals (Sweden)

    Cole Alicia

    2008-06-01

    Full Text Available Abstract Background 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. Methods 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. Results 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. Conclusion 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.

  7. The relationship between p53 gene and Alzheimer's disease%p53与阿尔茨海默病

    Institute of Scientific and Technical Information of China (English)

    黎巍威; 张伯礼; 王学美

    2009-01-01

    @@ p53是一种重要的抑癌基因,其所编码的蛋白质能抑制肿瘤的发生及其他恶性行为,正常细胞中p53蛋白半衰期短,含量极微,癌细胞和转化细胞中p53蛋白半衰期可延长到几小时,含量可高达100倍.目前对p53的研究主要在其与肿瘤的关系方面.然而p53本身及其调节分子非常复杂,决定着它可在不同的细胞和疾病中发挥不同的作用.

  8. 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.

  9. p53 as the main traffic controller of the cell signaling network.

    Science.gov (United States)

    Sebastian, Sinto; Azzariti, Amalia; Silvestris, Nicola; Porcelli, Letizia; Russo, Antonio; Paradiso, Angelo

    2010-06-01

    Among different pathological conditions that affect human beings, cancer has received a great deal of attention primarily because it leads to significant morbidity and mortality. This is essentially due to increasing world-wide incidence of this disease and the inability to discover the cause and molecular mechanisms by which normal human cells acquire the characteristics that define cancer cells. Since the discovery of p53 over a quarter of a century ago, it is now recognized that virtually all cell fate pathways of live cells and the decision to die are under the control of p53. Such extensive involvement indicates that p53 protein is acting as a major traffic controller in the cell signaling network. In cancer cells, many cell signaling pathways of normal human cells are rerouted towards immortalization and this is accomplished by the corruption of the main controllers of cell signaling pathways such as p53. This review highlights how p53 signaling activity is altered in cancer cells so that cells acquire the hallmarks of cancer including deregulated infinite self replicative potential.

  10. 3-MCPD 1-Palmitate Induced Tubular Cell Apoptosis In Vivo via JNK/p53 Pathways.

    Science.gov (United States)

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

    2016-05-01

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

  11. Acetylation of the pro-apoptotic factor, p53 in the hippocampus following cerebral ischemia and modulation by estrogen.

    Directory of Open Access Journals (Sweden)

    Limor Raz

    Full Text Available BACKGROUND: Recent studies demonstrate that acetylation of the transcription factor, p53 on lysine(373 leads to its enhanced stabilization/activity and increased susceptibility of cells to stress. However, it is not known whether acetylation of p53 is altered in the hippocampus following global cerebral ischemia (GCI or is regulated by the hormone, 17β-estradiol (17β-E(2, and thus, this study examined these issues. METHODOLOGY/PRINCIPAL FINDINGS: The study revealed that Acetyl p53-Lysine(373 levels were markedly increased in the hippocampal CA1 region after GCI at 3 h, 6 h and 24 h after reperfusion, an effect strongly attenuated by 17β-E(2. 17β-E(2 also enhanced interaction of p53 with the ubiquitin ligase, Mdm2, increased ubiquitination of p53, and induced its down-regulation, as well as attenuated elevation of the p53 transcriptional target, Puma. We also observed enhanced acetylation of p53 at a different lysine (Lys(382 at 3 h after reperfusion, and 17β-E(2 also markedly attenuated this effect. Furthermore, administration of an inhibitor of CBP/p300 acetyltransferase, which acetylates p53, was strongly neuroprotective of the CA1 region following GCI. In long-term estrogen deprived (LTED animals, the ability of 17β-E(2 to attenuate p53 acetylation was lost, and intriguingly, Acetyl p53-Lysine(373 levels were markedly elevated in sham (non-ischemic LTED animals. Finally, intracerebroventricular injections of Gp91ds-Tat, a specific NADPH oxidase (NOX2 inhibitor, but not the scrambled tat peptide control (Sc-Tat, attenuated acetylation of p53 and reduced levels of Puma following GCI. CONCLUSIONS/SIGNIFICANCE: The studies demonstrate that p53 undergoes enhanced acetylation in the hippocampal CA1 region following global cerebral ischemia, and that the neuroprotective agent, 17β-E(2, markedly attenuates the ischemia-induced p53 acetylation. Furthermore, following LTED, the suppressive effect of 17β-E(2 on p53 acetylation is lost, and p53

  12. Combining p53 stabilizers with metformin induces synergistic apoptosis through regulation of energy metabolism in castration-resistant prostate cancer.

    Science.gov (United States)

    Chen, Long; Ahmad, Nihal; Liu, Xiaoqi

    2016-01-01

    Since altered energy metabolism is a hallmark of cancer, many drugs targeting metabolic pathways are in active clinical trials. The tumor suppressor p53 is often inactivated in cancer, either through downregulation of protein or loss-of-function mutations. As such, stabilization of p53 is considered as one promising approach to treat those cancers carrying wild type (WT) p53. Herein, SIRT1 inhibitor Tenovin-1 and polo-like kinase 1 (Plk1) inhibitor BI2536 were used to stabilize p53. We found that both Tennovin-1 and BI2536 increased the anti-neoplastic activity of metformin, an inhibitor of oxidative phosphorylation, in a p53 dependent manner. Since p53 has also been shown to regulate metabolic pathways, we further analyzed glycolysis and oxidative phosphorylation upon drug treatments. We showed that both Tennovin-1 and BI2536 rescued metformin-induced glycolysis and that both Tennovin-1 and BI2536 potentiated metformin-associated inhibition of oxidative phosphorylation. Of significance, castration-resistant prostate cancer (CRPC) C4-2 cells show a much more robust response to the combination treatment than the parental androgen-dependent prostate cancer LNCaP cells, indicating that targeting energy metabolism with metformin plus p53 stabilizers might be a valid approach to treat CRPC carrying WT p53.

  13. HDAC inhibitors show differential epigenetic regulation and cell survival strategies on p53 mutant colon cancer cells.

    Science.gov (United States)

    R, Mahalakshmi; P, Husayn Ahmed; Mahadevan, Vijayalakshmi

    2017-03-06

    Besides inactivating tumour suppressor activity in cells, mutations in p53 confer significant oncogenic functions and promote metastasis and resistance to anti cancer therapy. A variety of therapies involving genetic and epigenetic signalling events regulate tumorogenesis and progression in such cases. Pharmacological interventions with HDAC inhibitors have shown promise in therapy. This work explores the changes in efficacy of the four HDAC inhibitors SAHA, MS-275, valproic acid and sodium butyrate on a panel of colon cancer cell lines - HCT116 (p53 wt), HCT116 p53-/-, HT29 and SW480 (with mutations in p53). Clonogenic assays, gene profiling and epigenetic expression done on these cells point to p53 dependent differential activity of the 4 HDAC inhibitors which also elevate methylation levels in p53 mutant cell lines. In silico modelling establishes the alterations in interactions that lead to such differential activity of valproic acid, one of the inhibitors considered for the work. Molecular Dynamic simulations carried out on the valproic acid complex ensure stability of the complex. This work establishes a p53 dependent epigenetic signalling mechanism triggered by HDAC inhibition expanding the scope of HDAC inhibitors in adjuvant therapy for p53 mutant tumours.

  14. 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.

  15. RAS AND p53 EXPRESSION IN HUMAN THYROID CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To investigate the possible interaction between the ras and p53 genes over-expression in thyroid carcinoma, and whether there is a correlation between the ras and p53 over-expression and clinicopathological criteria. Methods: Eighty patients with thyroid lesions were examined for expression of ras and p53 genes by the labeled streptavidin biotin peroxidase (LSAB) method. Of these patients, 54 were diagnosed (average age: 39.9± 15.9 years) with malignant lesions. Of those included in the study, 31 has papillary carcinoma, 13 had follicular carcinoma, 7 had medullary carcinoma, 3 had undifferentiated carcinoma and 19 were stratified to stage I, 28 to stage II, 2 to stage III and 5 to stage IV according to TNM staging system. Twenty-six benign nodular thyroid disorders were studied as control. Results: Positive immunostain results for ras and p53 genes were statistically significant between thyroid carcinomas and benign disorders (90.7% vs 23%, 55.5% vs 30.7%, P<0.05). Both p53 and ras overexpressions coexisted in 30 thyroid carcinomas, and of these, 3 died and 5 had recurrences within 4 years. Conclusions: Activation of ras gene and inactivation of p53 gene were cooperatively associated in thyroid tumorigenesis. The concurrent overexpressions of ras and p53 could result in a poor prognosis.

  16. HEXIM1, a New Player in the p53 Pathway

    Directory of Open Access Journals (Sweden)

    Nge Cheong

    2013-07-01

    Full Text Available 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.

  17. p53-dependent apoptosis suppresses radiation-induced teratogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Norimura, Toshiyuki [Univ. of Occupational and Environmental Health, Kitakyushu, Fukuoka (Japan). School of Medicine

    1999-06-01

    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{sup -/-}) and wild-type (p53{sup +/+}) mice. After X-irradiation with 2 Gy on day 9.5 of gestation, p53{sup -/-} mice showed a 70% incidence of anomalies and a 7% incidence of deaths, whereas p53{sup +/+} 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{sup +/+} fetuses but not at all in those of the p53{sup -/-} 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)

  18. 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.

  19. 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.

  20. A dynamic P53-MDM2 model with time delay

    Energy Technology Data Exchange (ETDEWEB)

    Mihalas, Gh.I. [Department of Biophysics and Medical Informatics, University of Medicine and Pharmacy, Piata Eftimie Murgu, nr. 3, 300041 Timisoara (Romania)]. E-mail: mihalas@medinfo.umft.ro; Neamtu, M. [Department of Forecasting, Economic Analysis, Mathematics and Statistics, West University of Timisoara, Str. Pestalozzi, nr. 14A, 300115 Timisoara (Romania)]. E-mail: mihaela.neamtu@fse.uvt.ro; Opris, D. [Department of Applied Mathematics, West University of Timisoara, Bd. V. Parvan, nr. 4, 300223 Timisoara (Romania)]. E-mail: opris@math.uvt.ro; Horhat, R.F. [Department of Biophysics and Medical Informatics, University of Medicine and Pharmacy, Piata Eftimie Murgu, nr. 3, 300041 Timisoara (Romania)]. E-mail: rhorhat@yahoo.com

    2006-11-15

    Specific activator and repressor transcription factors which bind to specific regulator DNA sequences, play an important role in gene activity control. Interactions between genes coding such transcription factors should explain the different stable or sometimes oscillatory gene activities characteristic for different tissues. Starting with the model P53-MDM2 described into [Mihalas GI, Simon Z, Balea G, Popa E. Possible oscillatory behaviour in P53-MDM2 interaction computer simulation. J Biol Syst 2000;8(1):21-9] and the process described into [Kohn KW, Pommier Y. Molecular interaction map of P53 and MDM2 logic elements, which control the off-on switch of P53 in response to DNA damage. Biochem Biophys Res Commun 2005;331:816-27] we enveloped a new model of this interaction. Choosing the delay as a bifurcation parameter we study the direction and stability of the bifurcating periodic solutions. Some numerical examples are finally given for justifying the theoretical results.

  1. Notch pathway is involved in high glucose-induced apoptosis in podocytes via Bcl-2 and p53 pathways.

    Science.gov (United States)

    Gao, Feng; Yao, Min; Shi, Yonghong; Hao, Jun; Ren, Yunzhuo; Liu, Qingjuan; Wang, Xiaomeng; Duan, Huijun

    2013-05-01

    Recent studies have shown that Notch pathway plays a key role in the pathogenesis of diabetic nephropathy (DN), however, the exact mechanisms remain elusive. Here we demonstrated that high glucose (HG) upregulated Notch pathway in podocytes accompanied with the alteration of Bcl-2 and p53 pathways, subsequently leading to podocytes apoptosis. Inhibition of Notch pathway by chemical inhibitor or specific short hairpin RNA (shRNA) vector in podocytes prevented Bcl-2- and p53-dependent cell apoptosis. These findings suggest that Notch pathway mediates HG-induced podocytes apoptosis via Bcl-2 and p53 pathways.

  2. Human Immunodeficiency Virus Type 1 Nef Binds to Tumor Suppressor p53 and Protects Cells against p53-Mediated Apoptosis

    OpenAIRE

    2002-01-01

    The nef gene product of human immunodeficiency virus type 1 (HIV-1) is important for the induction of AIDS, and key to its function is its ability to manipulate T-cell function by targeting cellular signal transduction proteins. We reported that Nef coprecipitates a multiprotein complex from cells which contains tumor suppressor protein p53. We now show that Nef interacts directly with p53. Binding assays showed that an N-terminal, 57-residue fragment of Nef (Nef 1-57) contains the p53-bindin...

  3. Analyses of p53 antibodies in sera of patients with lung carcinoma define immunodominant regions in the p53 protein.

    OpenAIRE

    Schlichtholz, B.; Trédaniel, J.; Lubin, R; Zalcman, G.; Hirsch, A.; Soussi, T

    1994-01-01

    Antibodies specific for human p53 were analysed in sera of lung cancer patients. We detected p53 antibodies in the sera of 24% (10/42) of patients with lung carcinoma. The distribution was as follows: 4/9 small-cell lung carcinomas (SCLCs), 2/18 squamous cell lung carcinomas (SCCs), 2/10 adenocarcinomas (ADCs) and 2/5 large-cell lung carcinomas (LCCs). p53 antibodies were always present at the time of diagnosis and did not appear during progression of the disease. Using an original peptide-ma...

  4. 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).

  5. Nanoparticle-mediated p53 gene therapy for tumor inhibition

    OpenAIRE

    Sharma, Blanka; Ma, Wenxue; Adjei, Isaac Morris; Panyam, Jayanth; Dimitrijevic, Sanja; Labhasetwar, Vinod

    2011-01-01

    The p53 tumor suppressor gene is mutated in 50% of human cancers, resulting in more aggressive disease with greater resistance to chemotherapy and radiation therapy. Advances in gene therapy technologies offer a promising approach to restoring p53 function. We have developed polymeric nanoparticles (NPs), based on poly (lactic-co-glycolic acid), that provide sustained intracellular delivery of plasmid DNA, resulting in sustained gene expression without vector-associated toxicity. Our previous...

  6. Dynamics of p53: A Master Decider of Cell Fate.

    Science.gov (United States)

    Luo, Qingyin; Beaver, Jill M; Liu, Yuan; Zhang, Zunzhen

    2017-02-09

    Cellular stress-induced temporal alterations-i.e., dynamics-are typically exemplified  by the dynamics of p53 that serve as a master to determine cell fate. p53 dynamics were initially  identified as the variations of p53 protein levels. However, a growing number of studies have  shown that p53 dynamics are also manifested in variations in the activity, spatial location, and  posttranslational modifications of p53 proteins, as well as the interplay among all p53 dynamical  features. These are essential in determining a specific outcome of cell fate. In this review, we  discuss the importance of the multifaceted features of p53 dynamics and their roles in the cell fate  decision process, as well as their potential applications in p53-based cancer therapy. The review  provides new insights into p53 signaling pathways and their potentials in the development of new  strategies in p53-based cancer therapy.

  7. The p53 Transcriptional Network Influences Microglia Behavior and Neuroinflammation.

    Science.gov (United States)

    Aloi, Macarena S; Su, Wei; Garden, Gwenn A

    2015-01-01

    The tumor-suppressor protein p53 belongs to a family of proteins that play pivotal roles in multiple cellular functions including cell proliferation, cell death, genome stability, and regulation of inflammation. Neuroinflammation is a common feature of central nervous system (CNS) pathology, and microglia are the specialized resident population of CNS myeloid cells that initiate innate immune responses. Microglia maintain CNS homeostasis through pathogen containment, phagocytosis of debris, and initiation of tissue-repair cascades. However, an unregulated pro-inflammatory response can lead to tissue injury and dysfunction in both acute and chronic inflammatory states. Therefore, regulation of the molecular signals that control the induction, magnitude, and resolution of inflammation are necessary for optimal CNS health. We and others have described a novel mechanism by which p53 transcriptional activity modulates microglia behaviors in vitro and in vivo. Activation of p53 induces expression of microRNAs (miRNAs) that support microglia pro-inflammatory functions and suppress anti-inflammatory and tissue repair behaviors. In this review, we introduce the previously described roles of the p53 signaling network and discuss novel functions of p53 in the microglia-mediated inflammatory response in CNS health and disease. Ultimately, improved understanding of the molecular regulators modulated by p53 transcriptional activity in microglia will enhance the development of rational therapeutic strategies to harness the homeostatic and tissue repair functions of microglia.

  8. 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.

  9. 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.

  10. Association of Human Papilloma Virus 16 Infection and p53 Polymorphism among Tobacco using Oral Leukoplakia Patients: A Clinicopathologic and Genotypic Study

    OpenAIRE

    Seema Sikka; Pranav Sikka

    2014-01-01

    Background: Human papillomavirus (HPV) and p53 alterations are speculated to play a role in carcinogenesis. This study was carried out to find out the association of HPV and p53 with precancerous lesions of the oral cavity such as leukoplakia: The objective of this study was to find the association among human papilloma virus (HPV) 16 infections and p53 polymorphism in tobacco using the oral leukoplakia patients. Methods: A total of 91 oral leukoplakia patients and 100 controls were rando...

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

    Science.gov (United States)

    2014-09-01

    Approaches to Target p53 Loss and Gain-of-Function in Triple Negative Breast Cancer PRINCIPAL INVESTIGATOR: Jennifer A. Pietenpol, Ph.D...Biologic, and Chemical Approaches to Target p53 Loss and Gain-of-Function in Triple Negative Breast Cancer 5a. CONTRACT NUMBER...states resulting from alterations in the p53 signaling pathway in triple negative breast cancer (TNBC). Development of therapies for TNBC is a

  12. Che-1/AATF: a critical co-factor for both wild type- and mutant-p53 proteins

    Directory of Open Access Journals (Sweden)

    Tiziana eBruno

    2016-02-01

    Full Text Available The p53 protein is a key player in a wide range of protein networks that allow the state of good health of the cell. Not surprisingly, mutations of the p53 gene are one of the most common alterations associated to cancer cells. Mutated forms of p53 (mtp53 not only lose the ability to protect the integrity of the genetic heritage of the cell, but acquire pro-oncogenic functions, behaving like dangerous accelerators of transformation and tumor progression. In recent years, many studies focused on investigating possible strategies aiming to counteract this mutant p53 gain of function but the results have not always been satisfactory. Che-1/AATF is a nuclear protein that binds to RNA polymerase II and plays a role in multiple fundamental processes, including control of transcription, cell cycle regulation, DNA damage response and apoptosis. Several studies showed Che-1/AATF as an important endogenous regulator of p53 expression and activity in a variety of biological processes. Notably, this same regulation was more recently observed also on mtp53. The depletion of Che-1/AATF strongly reduces the expression of mutant p53 in several tumors in vitro and in vivo, making the cells an easier target for chemotherapy treatments. In this mini review, we report an overview of Che-1/AATF functions and discuss a possible role of Che-1/AATF in cancer therapy, with particular regard to its action on p53/mtp53.

  13. The human TLR innate immune gene family is differentially influenced by DNA stress and p53 status in cancer cells.

    Science.gov (United States)

    Shatz, Maria; Menendez, Daniel; Resnick, Michael A

    2012-08-15

    The transcription factor p53 regulates genes associated with a wide range of functions, including the Toll-like receptor (TLR) set of innate immunity genes, suggesting that p53 also modulates the human immune response. The TLR family comprises membrane glycoproteins that recognize pathogen-associated molecular patterns (PAMP) and mediate innate immune responses, and TLR agonists are being used as adjuvants in cancer treatments. Here, we show that doxorubicin, 5-fluorouracil, and UV and ionizing radiation elicit changes in TLR expression that are cell line- and damage-specific. Specifically, treatment-induced expression changes led to increased downstream cytokine expression in response to ligand stimulation. The effect of DNA stressors on TLR expression was mainly mediated by p53, and several p53 cancer-associated mutants dramatically altered the pattern of TLR gene expression. In all cell lines tested, TLR3 induction was p53-dependent, whereas induction of TLR9, the most stress-responsive family member, was less dependent on status of p53. In addition, each of the 10 members of the innate immune TLR gene family tested was differentially inducible. Our findings therefore show that the matrix of p53 status, chromosome stress, and responsiveness of individual TLRs should be considered in TLR-based cancer therapies.

  14. The expanding regulatory universe of p53 in gastrointestinal cancer.

    Science.gov (United States)

    Fesler, Andrew; Zhang, Ning; Ju, Jingfang

    2016-01-01

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

  15. 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.

  16. Regulation of p53 is critical for vertebrate limb regeneration.

    Science.gov (United States)

    Yun, Maximina H; Gates, Phillip B; Brockes, Jeremy P

    2013-10-22

    Extensive regeneration of the vertebrate body plan is found in salamander and fish species. In these organisms, regeneration takes place through reprogramming of differentiated cells, proliferation, and subsequent redifferentiation of adult tissues. Such plasticity is rarely found in adult mammalian tissues, and this has been proposed as the basis of their inability to regenerate complex structures. Despite their importance, the mechanisms underlying the regulation of the differentiated state during regeneration remain unclear. Here, we analyzed the role of the tumor-suppressor p53 during salamander limb regeneration. The activity of p53 initially decreases and then returns to baseline. Its down-regulation is required for formation of the blastema, and its up-regulation is necessary for the redifferentiation phase. Importantly, we show that a decrease in the level of p53 activity is critical for cell cycle reentry of postmitotic, differentiated cells, whereas an increase is required for muscle differentiation. In addition, we have uncovered a potential mechanism for the regulation of p53 during limb regeneration, based on its competitive inhibition by ΔNp73. Our results suggest that the regulation of p53 activity is a pivotal mechanism that controls the plasticity of the differentiated state during regeneration.

  17. Conversion of Fibroblasts to Neural Cells by p53 Depletion

    Directory of Open Access Journals (Sweden)

    Di Zhou

    2014-12-01

    Full Text Available Conversion from fibroblasts to neurons has recently been successfully induced. However, the underlying mechanisms are poorly understood. Here, we find that depletion of p53 alone converts fibroblasts into all three major neural lineages. The induced neuronal cells express multiple neuron-specific proteins and generate action potentials and transmitter-receptor-mediated currents. Surprisingly, depletion does not affect the well-known tumorigenic p53 target, p21. Instead, knockdown of p53 upregulates neurogenic transcription factors, which in turn boosts fibroblast-neuron conversion. p53 binds the promoter of the neurogenic transcription factor Neurod2 and regulates its expression during fibroblast-neuron conversion. Furthermore, our method provides a high efficiency of conversion in late-passage fibroblasts. Genome-wide transcriptional analysis shows that the p53-deficiency-induced neurons exhibit an expression profile different from parental fibroblasts and similar to control-induced neurons. The results may help to understand and improve neural conversion mechanisms to develop robust neuron-replacement therapy strategies.

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

    Directory of Open Access Journals (Sweden)

    Rizos Helen

    2011-05-01

    Full Text Available Abstract Background 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. Methods 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. Results 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. Conclusions These results indicate that P53 target genes involved in apoptosis and cell

  19. Mechanisms of genotoxin-induced transcription and hypermutation in p53

    Directory of Open Access Journals (Sweden)

    Burkala Evan

    2006-12-01

    Full Text Available Abstract It is widely assumed that genotoxin-induced damage (e.g., G-to-T transversions to the tumor suppressor gene, p53, is a direct cause of cancer. However, genotoxins also induce the stress response, which upregulates p53 transcription and the formation of secondary structures from ssDNA. Since unpaired bases are thermodynamically unstable and intrinsically mutable, increased transcription could be the cause of hypermutation, and thus cancer. Support for this hypothesis has been obtained by analyzing 6662 mutations in all types of cancer compared to lung and colon cancers, using the p53 mutation database. The data suggest that genotoxins have two independent effects: first, they induce p53 transcription, which increases the number of mutable bases that determine the incidence of cancer. Second, genotoxins may alter the fate, or ultimate mutation of a mutable base, for example, by causing more of the available mutable Gs to mutate to T, leaving fewer to mutate to A. Such effects on the fate of mutable bases have no impact on the incidence of cancer, as both types of mutations lead to cancer.

  20. 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.

  1. Distinct Rayleigh scattering from hot spot mutant p53 proteins reveals cancer cells.

    Science.gov (United States)

    Jun, Ho Joon; Nguyen, Anh H; Kim, Yeul Hong; Park, Kyong Hwa; Kim, Doyoun; Kim, Kyeong Kyu; Sim, Sang Jun

    2014-07-23

    The scattering of light redirects and resonances when an electromagnetic wave interacts with electrons orbits in the hot spot core protein and oscillated electron of the gold nanoparticles (AuNP). This report demonstrates convincingly that resonant Rayleigh scattering generated from hot spot mutant p53 proteins is correspondence to cancer cells. Hot spot mutants have unique local electron density changes that affect specificity of DNA binding affinity compared with wild types. Rayleigh scattering changes introduced by hot-spot mutations were monitored by localized surface plasmon resonance (LSPR) shift changes. The LSPR λmax shift for hot-spot mutants ranged from 1.7 to 4.2 nm for mouse samples and from 0.64 nm to 2.66 nm for human samples, compared to 9.6 nm and 15 nm for wild type and mouse and human proteins, respectively with a detection sensitivity of p53 concentration at 17.9 nM. It is interesting that hot-spot mutants, which affect only interaction with DNA, launches affinitive changes as considerable as wild types. These changes propose that hot-spot mutants p53 proteins can be easily detected by local electron density alterations that disturbs the specificity of DNA binding of p53 core domain on the surface of the DNA probed-nanoplasmonic sensor.

  2. Methionine sulfoxide reductase A regulates cell growth through the p53-p21 pathway

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seung Hee [Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717 (Korea, Republic of); Kim, Hwa-Young, E-mail: hykim@ynu.ac.kr [Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717 (Korea, Republic of)

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Down-regulation of MsrA inhibits normal cell proliferation. Black-Right-Pointing-Pointer MsrA deficiency leads to an increase in p21 by enhanced p53 acetylation. Black-Right-Pointing-Pointer Down-regulation of MsrA causes cell cycle arrest at the G{sub 2}/M stage. Black-Right-Pointing-Pointer MsrA is a regulator of cell growth that mediates the p53-p21 pathway. -- Abstract: MsrA is an oxidoreductase that catalyzes the stereospecific reduction of methionine-S-sulfoxide to methionine. Although MsrA is well-characterized as an antioxidant and has been implicated in the aging process and cellular senescence, its roles in cell proliferation are poorly understood. Here, we report a critical role of MsrA in normal cell proliferation and describe the regulation mechanism of cell growth by this protein. Down-regulation of MsrA inhibited cell proliferation, but MsrA overexpression did not promote it. MsrA deficiency led to an increase in p21, a major cyclin-dependent kinase inhibitor, thereby causing cell cycle arrest at the G{sub 2}/M stage. While protein levels of p53 were not altered upon MsrA deficiency, its acetylation level was significantly elevated, which subsequently activated p21 transcription. The data suggest that MsrA is a regulator of cell growth that mediates the p53-p21 pathway.

  3. Mutant p53: a novel target for the treatment of patients with triple-negative breast cancer?

    Science.gov (United States)

    Synnott, N C; Murray, A; McGowan, P M; Kiely, M; Kiely, P A; O'Donovan, N; O'Connor, D P; Gallagher, W M; Crown, J; Duffy, M J

    2017-01-01

    The identification and validation of a targeted therapy for patients with triple-negative breast cancer (TNBC) is currently one of the most urgent needs in breast cancer therapeutics. One of the key reasons for the failure to develop a new therapy for this subgroup of breast cancer patients has been the difficulty in identifying a highly prevalent, targetable molecular alteration in these tumors. Recently however, the p53 gene was found to be mutated in approximately 80% of basal/TNBC, raising the possibility that targeting the mutant p53 protein product might be a new approach for the treatment of this form of breast cancer. In this study, we investigated the anti-cancer activity of PRIMA-1 and PRIMA-1(MET) (APR-246), two compounds which were previously reported to reactivate mutant p53 and convert it to a form with wild-type (WT) properties. Using a panel of 18 breast cancer cell lines and 2 immortalized breast cell lines, inhibition of proliferation by PRIMA-1 and PRIMA-1(MET) was found to be cell-line dependent, but independent of cell line molecular subtype. Although response was independent of molecular subtype, p53 mutated cell lines were significantly more sensitive to PRIMA-1(MET) than p53 WT cells (p = 0.029). Furthermore, response (measured as IC50 value) correlated significantly with p53 protein level as measured by ELISA (p = 0.0089, r=-0.57, n = 19). In addition to inhibiting cell proliferation, PRIMA-1(MET) induced apoptosis and inhibited migration in a p53 mutant-dependent manner. Based on our data, we conclude that targeting mutant p53 with PRIMA-1(MET) is a potential new approach for treating p53-mutated breast cancer, including the subgroup with triple-negative (TN) disease.

  4. COX-2 and p53 in human sinonasal cancer

    DEFF Research Database (Denmark)

    Holmila, Reetta; Cyr, Diane; Luce, Danièle

    2008-01-01

    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 components......The causal role of wood-dust exposure in sinonasal cancer (SNC) has been established in epidemiological studies, but the mechanisms of SNC carcinogenesis are still largely unknown. Increased amounts of COX-2 are found in both premalignant and malignant tissues, and experimental evidence link 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 nonsmokers...

  5. p53 and survival in early onset breast cancer

    DEFF Research Database (Denmark)

    Gentile, M; Bergman Jungeström, M; Olsen, K E;

    1999-01-01

    The p53 protein has proven to be central in tumorigenesis by its cell cycle regulatory properties and both gene mutations and protein accumulation have been associated with poor prognosis in breast cancer. The present study was undertaken to investigate the prognostic significance of gene mutations......, p53 protein accumulation and of loss of heterozygosity (LOH) at the TP53 locus in young (age breast cancer patients. In total, gene mutations were found in 21 of the 123 patients (17%), LOH in 20 of the 47 informative cases (43%) and protein accumulation in 47 of the 102 available cases...... in this as well as other studies, p53 protein accumulation is frequently found in young breast cancer patients, but this protein overexpression appears to be of minor significance for survival. Nevertheless, the present report also suggests that specific mutations contribute substantially to tumour aggressiveness....

  6. Direct interaction of the hepatitis B virus HBx protein with p53 leads to inhibition by HBx of p53 response element-directed transactivation.

    OpenAIRE

    1995-01-01

    Hepatitis B virus is a major risk factor in human hepatocellular carcinomas. We have used protein affinity chromatography to show that the 17-kDa hepatitis B virus gene product, HBx, binds directly to the human tumor suppressor gene product, p53. Interaction of HBx with p53 did not prevent p53 from specifically binding DNA. Instead, HBx enhanced p53's oligomerization state on a DNA oligonucleotide containing a p53 response element. Optimal binding of HBx to p53 required intact p53, but weaker...

  7. 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.

  8. P53 Suppression of Homologous Recombination and Tumorigenesis

    Science.gov (United States)

    2013-07-01

    Medium (DMEM) supplemented with 10,000 U/mL penicillin , 10,000 µg/mL streptomycin, and 25 µg/mL Amphotericin B (Cellgro, VA). Cells were grown at 37...p53-/-) cells were maintained at 5% CO2 in DMEM supplemented with 10% fetal calf serum and penicillin . HCT116 (p53-/-) cells were transfected using...binding protein are hypersensitive to γ- radiation and invariably develop myelodysplastic/myeloproliferative neoplasm. Exp Hematol. 2012 Apr;40(4):295

  9. 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.

  10. Super p53 for Treatment of Ovarian Cancer

    Science.gov (United States)

    2016-07-01

    AWARD NUMBER: W81XWH-15-1-0036 TITLE: Super p53 for Treatment of Ovarian Cancer PRINCIPAL INVESTIGATOR: Carol S. Lim CONTRACTING...for Treatment of Ovarian Cancer 5b. GRANT NUMBER W81XWH-15-1 -0036 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Carol S. Lim 5e...killing ovarian cancer cells in vitro. This is unreported, novel finding paves the way for using super p53 for ovarian cancer treatment . Main

  11. p53 isoform Δ113p53/Δ133p53 promotes DNA double-strand break repair to protect cell from death and senescence in response to DNA damage.

    Science.gov (United States)

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

    2015-03-01

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

  12. FOXO1 downregulation is associated with worse outcome in bladder cancer and adds significant prognostic information to p53 overexpression.

    Science.gov (United States)

    Lloreta, Josep; Font-Tello, Alba; Juanpere, Núria; Frances, Albert; Lorenzo, Marta; Nonell, Lara; de Muga, Silvia; Vázquez, Ivonne; Cecchini, Lluís; Hernández-Llodrà, Silvia

    2017-01-10

    Nuclear FOXOs mediate cell cycle arrest and promote apoptosis. FOXOs and p53 could have similar effects as tumor suppressor genes. In spite of extensive literature, little is known about the role of FOXO1 and its relationship with p53 status in bladder cancer. Expression of FOXO1 and p53 were analyzed by immunohistochemistry in 162 urothelial carcinomas (UC). Decreased FOXO1 expression, p53 overexpression and the combination FOXO1 downregulation/p53 overexpression were strongly associated with high grade (P=.030; P=.017; P=.004, respectively), high stage (P=.0001; Pp53 overexpression was associated with tumor progression (HR=3.18, 95% CI 1.19-8.48 P=.02), but this association was even stronger if having any alteration in any of the two genes was considered (HR=3.51, 95% CI 1.34-9.21 P=.01). Having both FOXO1 downregulation and p53 overexpression was associated with disease recurrence (HR=2.75, 95% CI 1.06-7.13 P=.03). In the analysis of the different subgroups, having any alteration in any of the two genes was associated with progression in low grade (P=.005) and pTa (P=.006) tumors. Finally, the combined FOXO1 downregulation/p53 overexpression was associated with disease recurrence specifically in high grade (P=.04) and in pT1 stage tumors (P=.007). Adding FOXO1 expression to the immunohistochemical analysis of p53 can provide relevant prognostic information on progression and recurrence of bladder cancer. It may be particularly informative on the risk of progression in the more indolent and on the risk of recurrence in the more aggressive tumors.

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

    OpenAIRE

    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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. Morphological Heterogeneity of p53 Positive and p53 Negative Nuclei in Breast Cancers Stratified by Clinicopathological Variables

    Directory of Open Access Journals (Sweden)

    Katrin Friedrich

    1997-01-01

    Full Text Available The study was aimed to detect differences in nuclear morphology between nuclear populations as well as between tumours with different p53 expression in breast cancers with different clinicopathological features, which also reflect the stage of tumour progression. The p53 immunohistochemistry was performed on paraffin sections from 88 tumour samples. After the cells had been localised by means of an image cytometry workstation and their immunostaining had been categorised visually, the sections were destained and stained by the Feulgen protocol. The nuclei were relocated and measured cytometrically by the workstation.

  19. 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...

  20. Immunohistochemical detection of P53 and Mdm2 in vitiligo

    Science.gov (United States)

    Bakry, Ola A.; Hammam, Mostafa A.; Wahed, Moshira M. Abdel

    2012-01-01

    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. PMID:23189248

  1. Epimorphic regeneration in mice is p53-independent.

    Science.gov (United States)

    Arthur, L Matthew; Demarest, Renee M; Clark, Lise; Gourevitch, Dmitri; Bedelbaeva, Kamila; Anderson, Rhonda; Snyder, Andrew; Capobianco, Anthony J; Lieberman, Paul; Feigenbaum, Lionel; Heber-Katz, E

    2010-09-15

    The process of regeneration is most readily studied in species of sponge, hydra, planarian and salamander (i.e., newt and axolotl). The closure of MRL mouse ear pinna through-and-through holes provides a mammalian model of unusual wound healing/regeneration in which a blastema-like structure closes the ear hole and cartilage and hair follicles are replaced. Recent studies, based on a broad level of DNA damage and a cell cycle pattern of G₂/M "arrest," showed that p21(Cip1/Waf1) was missing from the MRL mouse ear and that a p21-null mouse could close its ear holes. Given the p53/p21 axis of control of DNA damage, cell cycle arrest, apoptosis and senescence, we tested the role of p53 in the ear hole regenerative response. Using backcross mice, we found that loss of p53 in MRL mice did not show reduced healing. Furthermore, cross sections of MRL. p53(-/-) mouse ears at 6 weeks post-injury showed an increased level of adipocytes and chondrocytes in the region of healing whereas MRL or p21(-/-) mice showed chondrogenesis alone in this same region, though at later time points. In addition, we also investigated other cell cycle-related mutant mice to determine how p21 was being regulated. We demonstrate that p16 and Gadd45 null mice show little healing capacity. Interestingly, a partial healing phenotype in mice with a dual Tgfβ/Rag2 knockout mutation was seen. These data demonstrate an independence of p53 signaling for mouse appendage regeneration and suggest that the role of p21 in this process is possibly through the abrogation of the Tgfβ/Smad pathway.

  2. 调节p53途径—提高癌症治疗效率%Modulating the p53 pathway may improve the efficiency of anti-cancer treatment

    Institute of Scientific and Technical Information of China (English)

    焦宏伟; 关婉怡; 刘东; 赵宝华

    2013-01-01

    p53肿瘤抑制蛋白,也被称为基因组监控因子,是一种保护细胞免受一系列生理逆境(例如致癌基因活化、辐射、有丝分裂压力、核糖体压力和化学损害)的转录控制因子.这些生理逆境会导致依赖于p53激活的信号产生,并通过复杂的相互作用网络定位到细胞核,起始转录或抑制许多基因的表达,这些基因与诱导生长停滞、修复、细胞凋亡、衰老或者改变新陈代谢有关.由于p53途径对于调控疾病有如此重要的作用,使得针对该途径的药物干预日益成为人们关注的焦点.本文对调节p53功能的最新研究进展进行综述,并对有关p53基因的癌症治疗前景进行展望.%The p53 tumor suppressor protein,also nicknamed the "guardian of the genome",is a transcription factor that protects cells against a range of physiological stresses,such as oncogene activation,radiation,mitotic stress,ribosomal stress and chemical insults.These events lead to signals that are relayed to p53 which gets activated,and gets localized to the nucleus through a complex network of interactions.It turns on a program of transcription or repression of myriad genes that induce growth arrest,repair,apoptosis,senescence or altered metabolism.P53 pathway has such an important role in modulating diseases.This makes pharmacological intervention in the p53 pathway to obtain an increasing focus of attention.We summarized recent developments that attempt to modulate the function of p53 and expected the future of on the p53 gene for anti-cancer treatment.

  3. Inactivation of p53 in Human Keratinocytes Leads to Squamous Differentiation and Shedding via Replication Stress and Mitotic Slippage.

    Science.gov (United States)

    Freije, Ana; Molinuevo, Rut; Ceballos, Laura; Cagigas, Marta; Alonso-Lecue, Pilar; Rodriguez, René; Menendez, Pablo; Aberdam, Daniel; De Diego, Ernesto; Gandarillas, Alberto

    2014-11-20

    Tumor suppressor p53 is a major cellular guardian of genome integrity, and its inactivation is the most frequent genetic alteration in cancer, rising up to 80% in squamous cell carcinoma (SCC). By adapting the small hairpin RNA (shRNA) technology, we inactivated endogenous p53 in primary epithelial cells from the epidermis of human skin. We show that either loss of endogenous p53 or overexpression of a temperature-sensitive dominant-negative conformation triggers a self-protective differentiation response, resulting in cell stratification and expulsion. These effects follow DNA damage and exit from mitosis without cell division. p53 preserves the proliferative potential of the stem cell compartment and limits the power of proto-oncogene MYC to drive cell cycle stress and differentiation. The results provide insight into the role of p53 in self-renewal homeostasis and help explain why p53 mutations do not initiate skin cancer but increase the likelihood that cancer cells will appear.

  4. Inactivation of p53 in Human Keratinocytes Leads to Squamous Differentiation and Shedding via Replication Stress and Mitotic Slippage

    Directory of Open Access Journals (Sweden)

    Ana Freije

    2014-11-01

    Full Text Available Tumor suppressor p53 is a major cellular guardian of genome integrity, and its inactivation is the most frequent genetic alteration in cancer, rising up to 80% in squamous cell carcinoma (SCC. By adapting the small hairpin RNA (shRNA technology, we inactivated endogenous p53 in primary epithelial cells from the epidermis of human skin. We show that either loss of endogenous p53 or overexpression of a temperature-sensitive dominant-negative conformation triggers a self-protective differentiation response, resulting in cell stratification and expulsion. These effects follow DNA damage and exit from mitosis without cell division. p53 preserves the proliferative potential of the stem cell compartment and limits the power of proto-oncogene MYC to drive cell cycle stress and differentiation. The results provide insight into the role of p53 in self-renewal homeostasis and help explain why p53 mutations do not initiate skin cancer but increase the likelihood that cancer cells will appear.

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

    Directory of Open Access Journals (Sweden)

    Arindam Datta

    2016-06-01

    Full Text Available 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 p53R273H (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.

  6. Benzyl Isothiocyanate potentiates p53 signaling and antitumor effects against breast cancer through activation of p53-LKB1 and p73-LKB1 axes

    Science.gov (United States)

    Xie, Bei; Nagalingam, Arumugam; Kuppusamy, Panjamurthy; Muniraj, Nethaji; Langford, Peter; Győrffy, Balázs; Saxena, Neeraj K.; Sharma, Dipali

    2017-01-01

    Functional reactivation of p53 pathway, although arduous, can potentially provide a broad-based strategy for cancer therapy owing to frequent p53 inactivation in human cancer. Using a phosphoprotein-screening array, we found that Benzyl Isothiocynate, (BITC) increases p53 phosphorylation in breast cancer cells and reveal an important role of ERK and PRAS40/MDM2 in BITC-mediated p53 activation. We show that BITC rescues and activates p53-signaling network and inhibits growth of p53-mutant cells. Mechanistically, BITC induces p73 expression in p53-mutant cells, disrupts the interaction of p73 and mutant-p53, thereby releasing p73 from sequestration and allowing it to be transcriptionally active. Furthermore, BITC-induced p53 and p73 axes converge on tumor-suppressor LKB1 which is transcriptionally upregulated by p53 and p73 in p53-wild-type and p53-mutant cells respectively; and in a feed-forward mechanism, LKB1 tethers with p53 and p73 to get recruited to p53-responsive promoters. Analyses of BITC-treated xenografts using LKB1-null cells corroborate in vitro mechanistic findings and establish LKB1 as the key node whereby BITC potentiates as well as rescues p53-pathway in p53-wild-type as well as p53-mutant cells. These data provide first in vitro and in vivo evidence of the integral role of previously unrecognized crosstalk between BITC, p53/LKB1 and p73/LKB1 axes in breast tumor growth-inhibition. PMID:28071670

  7. Translational approaches targeting the p53 pathway for anti-cancer therapy

    OpenAIRE

    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...

  8. 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

  9. 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.

  10. [Structural organization of the human p53 gene. I. Molecular cloning of the human p53 gene].

    Science.gov (United States)

    Bukhman, V L; Ninkina, N N; Chumakov, P M; Khilenkova, M A; Samarina, O P

    1987-09-01

    Human p53 gene was cloned from the normal human placenta DNA and DNA from the strain of human kidney carcinoma transplanted into nude mice. Representative gene library from tumor strain of human kidney carcinoma and library of 15 kb EcoRI fragments of DNA from normal human placenta were constructed. Maniatis gene library was also used. Five clones were isolated from kidney carcinoma library; they covered 27 kb and included full-length p53 gene of 19.5 kb and flanking sequences. From normal placenta libraries three overlapped clones were obtained. Restriction map of cloned sequences was constructed and polarity of the p53 gene determined. The first intron of the gene is large (10.4 kb); polymorphic BglII site was observed in this intron, which allows to discriminate between allelic genes. One of these (BglII-) is ten times more abundant that the other (BglII+). Both allelic genes are able to synthesize the 2.8 kb p53 gene.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lu Xiongbin; Lozano, Guillermina; Donehower, Lawrence A

    2003-01-28

    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-Zeo{sup R} 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{sup +/-} mouse fibroblasts show elevated levels of homologous recombination compared to their p53{sup +/+} 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.

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

    Science.gov (United States)

    Lu, Xiongbin; Lozano, Guillermina; Donehower, Lawrence A

    2003-01-28

    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-Zeo(R) 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.

  13. 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.

  14. Sequestration of p53 in the Cytoplasm by Adenovirus Type 12 E1B 55-Kilodalton Oncoprotein Is Required for Inhibition of p53-Mediated Apoptosis

    OpenAIRE

    2003-01-01

    The adenovirus E1B 55-kDa protein is a potent inhibitor of p53-mediated transactivation and apoptosis. The proposed mechanisms include tethering the E1B repression domain to p53-responsive promoters via direct E1B-p53 interaction. Cytoplasmic sequestration of p53 by the 55-kDa protein would impose additional inhibition on p53-mediated effects. To investigate further the role of cytoplasmic sequestration of p53 in its inhibition by the E1B 55-kDa protein we systematically examined domains in b...

  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)

    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.

  16. 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

    2016-01-01

    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 (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.

  17. p53 orchestrates between normal differentiation and cancer.

    Science.gov (United States)

    Rivlin, Noa; Koifman, Gabriela; Rotter, Varda

    2015-06-01

    During recent years, it is becoming more and more evident that there is a tight connection between abnormal differentiation processes and cancer. While cancer and stem cells are very different, especially in terms of maintaining genomic integrity, these cell types also share many similar properties. In this review, we aim to provide an over-view of the roles of the key tumor suppressor, p53, in regulating normal differentiation and function of both stem cells and adult cells. When these functions are disrupted, undifferentiated cells may become transformed. Understanding the function of p53 in stem cells and its role in maintaining the balance between differentiation and malignant transformation can help shed light on cancer initiation and propagation, and hopefully also on cancer prevention and therapy.

  18. Role of p53 Mammary Epithelial Cell Senescence

    Science.gov (United States)

    2005-05-01

    AD Award Number: DAMD17-02-1-0509 TITLE: Role of p53 Mammary Epithelial Cell Senescence PRINCIPAL INVESTIGATOR: Goberdhan P. Dimri, Ph.D. CONTRACTING ...type and However, Mucl , K-18, and ASMA were not expressed in luminal cell type groups [12,68]. Interestingly, a significant cells present in...13,17,27], the has also attracted a great interest in the field of breast cancer candidate mammary stem cells appear to be ESA+, Mucl -, research, and

  19. 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.

  20. Expression of p53 and p21 Protein in Transitional Mucosa Adjacent to Rectal Carcinoma and Its Clinical Implication

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To study the biopathological characteristics of the transitional mucosa adjacent to rectal carcinoma, 34 cases were subjected to mucin histochemical and immunohistochemical study to observe the expression of p53 and p21 protein in distal mucosa adjacent to rectal carcinoma and its relationship to the mucin change. The expression of p53 protein was found in 29. 4 % (10/34) of distal transitional mucosa in the cytoplasm of goblet cells, and its positive staining was within 4 cm from carcinoma margin. A11 p53 positive mucosa was transitional mucosa. Overexpression of p21 protein was found in 26.5 % (9/34) of distal transitional mucosa in cytoplasm of crypt cells, and its positive staining was within 2 cm from carcinoma margin. There was no relationship between the expression of p53 and p21 protein in carcinoma and that in transitional mucosa (P>0.05). These findings indicated that there was aberrant alteration of p53 and p21 genes in transitional mucosa adjacent to colorectal carcinoma, which provided further evidence that transitional mucosa was an unstable pre-cancerous change. The aberrant mucin change and genetic alteration in distal mucosa of rectal cancer is within 4 cm.

  1. Small-Molecule NSC59984 Restores p53 Pathway Signaling and Antitumor Effects against Colorectal Cancer via p73 Activation and Degradation of Mutant p53.

    Science.gov (United States)

    Zhang, Shengliang; Zhou, Lanlan; Hong, Bo; van den Heuvel, A Pieter J; Prabhu, Varun V; Warfel, Noel A; Kline, Christina Leah B; Dicker, David T; Kopelovich, Levy; El-Deiry, Wafik S

    2015-09-15

    The tumor-suppressor p53 prevents cancer development via initiating cell-cycle arrest, cell death, repair, or antiangiogenesis processes. Over 50% of human cancers harbor cancer-causing mutant p53. p53 mutations not only abrogate its tumor-suppressor function, but also endow mutant p53 with a gain of function (GOF), creating a proto-oncogene that contributes to tumorigenesis, tumor progression, and chemo- or radiotherapy resistance. Thus, targeting mutant p53 to restore a wild-type p53 signaling pathway provides an attractive strategy for cancer therapy. We demonstrate that small-molecule NSC59984 not only restores wild-type p53 signaling, but also depletes mutant p53 GOF. NSC59984 induces mutant p53 protein degradation via MDM2 and the ubiquitin-proteasome pathway. NSC59984 restores wild-type p53 signaling via p73 activation, specifically in mutant p53-expressing colorectal cancer cells. At therapeutic doses, NSC59984 induces p73-dependent cell death in cancer cells with minimal genotoxicity and without evident toxicity toward normal cells. NSC59984 synergizes with CPT11 to induce cell death in mutant p53-expressing colorectal cancer cells and inhibits mutant p53-associated colon tumor xenograft growth in a p73-dependent manner in vivo. We hypothesize that specific targeting of mutant p53 may be essential for anticancer strategies that involve the stimulation of p73 in order to efficiently restore tumor suppression. Taken together, our data identify NSC59984 as a promising lead compound for anticancer therapy that acts by targeting GOF-mutant p53 and stimulates p73 to restore the p53 pathway signaling.

  2. p53-dependent release of Alarmin HMGB1 is a central mediator of senescent phenotypes.

    Science.gov (United States)

    Davalos, Albert R; Kawahara, Misako; Malhotra, Gautam K; Schaum, Nicholas; Huang, Jiahao; Ved, Urvi; Beausejour, Christian M; Coppe, Jean-Philippe; Rodier, Francis; Campisi, Judith

    2013-05-13

    Cellular senescence irreversibly arrests proliferation in response to potentially oncogenic stress. Senescent cells also secrete inflammatory cytokines such as IL-6, which promote age-associated inflammation and pathology. HMGB1 (high mobility group box 1) modulates gene expression in the nucleus, but certain immune cells secrete HMGB1 as an extracellular Alarmin to signal tissue damage. We show that nuclear HMGB1 relocalized to the extracellular milieu in senescent human and mouse cells in culture and in vivo. In contrast to cytokine secretion, HMGB1 redistribution required the p53 tumor suppressor, but not its activator ATM. Moreover, altered HMGB1 expression induced a p53-dependent senescent growth arrest. Senescent fibroblasts secreted oxidized HMGB1, which stimulated cytokine secretion through TLR-4 signaling. HMGB1 depletion, HMGB1 blocking antibody, or TLR-4 inhibition attenuated senescence-associated IL-6 secretion, and exogenous HMGB1 stimulated NF-κB activity and restored IL-6 secretion to HMGB1-depleted cells. Our findings identify senescence as a novel biological setting in which HMGB1 functions and link HMGB1 redistribution to p53 activity and senescence-associated inflammation.

  3. Role of p53 in the cellular response following oleic acid accumulation in Chang liver cells.

    Science.gov (United States)

    Park, Eun-Jung; Lee, Ah Young; Chang, Seung-Hee; Yu, Kyeong-Nam; Kim, Jae-Ho; Cho, Myung-Haing

    2014-01-03

    Abnormal accumulation of fatty acids triggers the harmful cellular response called lipotoxicity. In this study, we investigated the cellular response following accumulation of oleic acid (OA), a monounsaturated fatty acid, in human Chang liver cells. OA droplets were distributed freely in the cytoplasm and/or degraded within lysosomes. OA exposure increased ATP production and concomitantly dilated mitochondria. At 24h after OA exposure, cell viability decreased slightly and was coupled with a reduction in mitochondrial Ca(2+) concentration, the alteration in cell viability was also associated with the generation of reactive oxygen species and changes in the cell cycle. Moreover, OA treatment increased the expression of autophagy- and apoptotic cell death-related proteins in a dose-dependent manner. Furthermore, we investigated the role of p53, a tumor suppressor protein, in the cellular response elicited by OA accumulation. OA-induced changes in cell viability and ATP production were rescued to control levels when cells were pretreated with pifithrin-alpha (PTA), a p53 inhibitor. By contrast, the expressions of LC3-II and perilipin, proteins required for lipophagy, were down-regulated by PTA pretreatment. Taken together, our results suggest that p53 plays a key role in the cellular response elicited by OA accumulation in Chang liver cells.

  4. p53-dependent release of Alarmin HMGB1 is a central mediator of senescent phenotypes

    Science.gov (United States)

    Kawahara, Misako; Malhotra, Gautam K.; Schaum, Nicholas; Huang, Jiahao; Ved, Urvi; Beausejour, Christian M.; Coppe, Jean-Philippe; Rodier, Francis

    2013-01-01

    Cellular senescence irreversibly arrests proliferation in response to potentially oncogenic stress. Senescent cells also secrete inflammatory cytokines such as IL-6, which promote age-associated inflammation and pathology. HMGB1 (high mobility group box 1) modulates gene expression in the nucleus, but certain immune cells secrete HMGB1 as an extracellular Alarmin to signal tissue damage. We show that nuclear HMGB1 relocalized to the extracellular milieu in senescent human and mouse cells in culture and in vivo. In contrast to cytokine secretion, HMGB1 redistribution required the p53 tumor suppressor, but not its activator ATM. Moreover, altered HMGB1 expression induced a p53-dependent senescent growth arrest. Senescent fibroblasts secreted oxidized HMGB1, which stimulated cytokine secretion through TLR-4 signaling. HMGB1 depletion, HMGB1 blocking antibody, or TLR-4 inhibition attenuated senescence-associated IL-6 secretion, and exogenous HMGB1 stimulated NF-κB activity and restored IL-6 secretion to HMGB1-depleted cells. Our findings identify senescence as a novel biological setting in which HMGB1 functions and link HMGB1 redistribution to p53 activity and senescence-associated inflammation. PMID:23649808

  5. Induction of p53-Specific Immunity by a p53 Synthetic Long Peptide Vaccine in Patients Treated for Metastatic Colorectal Cancer

    NARCIS (Netherlands)

    Speetjens, Frank M.; Kuppen, PeterJ. K.; Welters, Marij. J. P.; Essahsah, Farah; van den Brink, Anne Marie E. G. Voet; Lantrua, M. Graziella Kallenberg; Valentijn, A. Rob P. M.; Oostendorp, Jaap; Fathers, Lorraine M.; Nijman, Hans W.; Drijfhout, Jan W.; van de Velde, Cornelis J. H.; Melief, Cornelis J. M.; van der Burg, Sjoerd H.

    2009-01-01

    Purpose: The tumor-associated self-antigen p53 is commonly overexpressed in cancer, including colorectal cancer, and can serve as a target for immunotherapy. The safety and immunogenicity of a p53 synthetic long peptide (p53-SLP) vaccine were investigated in patients treated for metastatic colorecta

  6. Immunological and Clinical Effects of Vaccines Targeting p53-Overexpressing Malignancies

    NARCIS (Netherlands)

    Vermeij, R.; Leffers, N.; van der Burg, S. H.; Melief, C. J.; Daemen, T.; Nijman, H. W.

    2011-01-01

    Approximately 50% of human malignancies carry p53 mutations, which makes it a potential antigenic target for cancer immunotherapy. Adoptive transfer with p53-specific cytotoxic T-lymphocytes (CTL) and CD4(+) T-helper cells eradicates p53-overexpressing tumors in mice. Furthermore, p53 antibodies and

  7. 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.

  8. 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,

  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. 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.

  11. Evidence for allosteric variants of wild-type p53, a tumour suppressor protein.

    OpenAIRE

    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...

  12. Negative Regulation of Tumor Suppressor p53 by microRNA miR-504

    OpenAIRE

    2010-01-01

    Tumor suppressor p53 plays a central role in tumor prevention. p53 protein levels and activity are under a tight and complex regulation in cells to maintain the proper function of p53. microRNAs play a key role in the regulation of gene expression. Here we report the regulation of p53 through microRNA miR-504. miR-504 acts as a negative regulator of human p53 through its direct binding to two sites in p53 3′-UTR. Overexpression of miR-504 decreases p53 protein levels and functions in cells, i...

  13. Ribosomal protein S7 as a novel modulator of p53-MDM2 interaction: binding to MDM2, stabilization of p53 protein, and activation of p53 function.

    Science.gov (United States)

    Chen, D; Zhang, Z; Li, M; Wang, W; Li, Y; Rayburn, E R; Hill, D L; Wang, H; Zhang, R

    2007-08-01

    As a major negative regulator of p53, the MDM2 oncogene plays an important role in carcinogenesis and tumor progression. MDM2 promotes p53 proteasomal degradation and negatively regulates p53 function. The mechanisms by which the MDM2-p53 interaction is regulated are not fully understood, although several MDM2-interacting molecules have recently been identified. To search for novel MDM2-binding partners, we screened a human prostate cDNA library by the yeast two-hybrid assay using full-length MDM2 protein as the bait. Among the candidate proteins, ribosomal protein S7 was identified and confirmed as a novel MDM2-interacting protein. Herein, we demonstrate that S7 binds to MDM2, in vitro and in vivo, and that the interaction between MDM2 and S7 leads to modulation of MDM2-p53 binding by forming a ternary complex among MDM2, p53 and S7. This results in the stabilization of p53 protein through abrogation of MDM2-mediated p53 ubiquitination. Consequently, S7 overexpression increases p53 transactivational activities, induces apoptosis, and inhibits cell proliferation. The identification of S7 as a novel MDM2-interacting partner contributes to elucidation of the complex regulation of the MDM2-p53 interaction and has implications in cancer prevention and therapy.

  14. RPR-115135, a farnesyltransferase inhibitor, increases 5-FU- cytotoxicity in ten human colon cancer cell lines: role of p53.

    Science.gov (United States)

    Russo, Patrizia; Malacarne, Davide; Falugi, Carla; Trombino, Sonya; O'Connor, Patrick M

    2002-07-20

    A new non peptidic farnesyltransferase inhibitor, RPR-115135, in combination with 5-FU was studied in 10 human colon cancer cell lines (HCT-116, RKO, DLD-1, Colo-320, LoVo, SW-620, HT-29, HCT-15, Colo-205 and KM-12) carrying several mutations but well characterized for p53 and Ras status. We found that there was a slight tendency (not statistically significant) for the p53 inactivated cells to be less sensitive to 5-FU after 6 days continuous treatment. Simultaneous administration of RPR-115135 and 5-FU, at subtoxic concentrations, resulted in a synergistic enhancement of 5-FU cytotoxicity in the p53 wildtype cells (HCT-116, RKO, DLD-1, Colo-320, LoVo). In the p53 mutated cells (SW-620, HT-29, HCT-15, Colo-205, KM-12) the effect was very complicated. In HCT-15 the combination resulted in antagonism, in KM-12 in antagonism or in synergy (at different concentrations) and in SW-620, HT-29 and Colo-205 cells in synergy but only when 5-FU was administered at high concentrations. Growth inhibition could be accounted for on the basis of a specific cell cycle arrest phenotype (G2-M arrest), as assayed by flow cytometry, only in the p53 functioning cell lines. The combination RPR-115135 + 5-FU increases apoptotic events only in these cell lines. In the mutated cell lines no major alterations on cell cycle arrest phenotype and no induction of apoptosis was observed. Although RPR-115135 can potentiate the effect of 5-FU in cells in which p53 function is disrupted, these data suggest strongly that RPR-115135 significantly enhances the efficacy of 5-FU only when p53 is functioning.

  15. Distinct regulation of p53-mediated apoptosis by protein kinase calpha, delta, epsilon and zeta : evidence in yeast for transcription-dependent and -independent p53 apoptotic mechanisms

    OpenAIRE

    Coutinho, Isabel; Pereira, Clara; Pereira, Gil; Gonçalves, Jorge; Côrte-Real, Manuela; Saraiva, Lucília

    2011-01-01

    The role of individual protein kinase C (PKC) isoforms in the regulation of p53- mediated apoptosis is still uncertain. Using yeast cells co-expressing the human wild-type p53 and a single mammalian PKCa, d, e or z, we showed a differential regulation of p53- mediated apoptosis by these PKC isoforms. Whereas PKCa and z had no effect on p53 activity, PKCd and e stimulated a p53-mediated mitochondria-dependent apoptosis. Moreover, using pifithrin-a and -m, selective inhibitors of...

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

    Science.gov (United States)

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

    2003-11-01

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

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

    Science.gov (United States)

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

    2016-09-02

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

  18. Induction of Cullin 7 by DNA damage attenuates p53 function

    OpenAIRE

    2007-01-01

    The p53 tumor suppressor gene encodes a transcription factor, which is translationally and posttranslationally activated after DNA damage. In a proteomic screen for p53 interactors, we found that the cullin protein Cul7 efficiently associates with p53. After DNA damage, the level of Cul7 protein increased in a caffeine-sensitive, but p53-independent, manner. Down-regulation of Cul7 by conditional microRNA expression augmented p53-mediated inhibition of cell cycle progression. Ectopic expressi...

  19. Tumor suppressor p53 and its gain-of-function mutants in cancer

    OpenAIRE

    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...

  20. The p53 pathway in hematopoiesis: lessons from mouse models, implications for humans

    OpenAIRE

    Pant, Vinod; Quintás-Cardama, Alfonso; Lozano, Guillermina

    2012-01-01

    Aberrations in the p53 tumor suppressor pathway are associated with hematologic malignancies. p53-dependent cell cycle control, senescence, and apoptosis functions are actively involved in maintaining hematopoietic homeostasis under normal and stress conditions. Whereas loss of p53 function promotes leukemia and lymphoma development in humans and mice, increased p53 activity inhibits hematopoietic stem cell function and results in myelodysplasia. Thus, exquisite regulation of p53 activity is ...

  1. p53 acetylation enhances Taxol-induced apoptosis in human cancer cells.

    Science.gov (United States)

    Kim, Jae Hyeong; Yoon, Eun-Kyung; Chung, Hye-Jin; Park, Seong-Yeol; Hong, Kyeong-Man; Lee, Chang-Hun; Lee, Yeon-Su; Choi, Kyungho; Yang, Young; Kim, Kyungtae; Kim, In-Hoo

    2013-01-01

    Microtubule inhibitors (MTIs) such as Taxol have been used for treating various malignant tumors. Although MTIs have been known to induce cell death through mitotic arrest, other mechanisms can operate in MTI-induced cell death. Especially, the role of p53 in this process has been controversial for a long time. Here we investigated the function of p53 in Taxol-induced apoptosis using p53 wild type and p53 null cancer cell lines. p53 was upregulated upon Taxol treatment in p53 wild type cells and deletion of p53 diminished Taxol-induced apoptosis. p53 target proteins including MDM2, p21, BAX, and β-isoform of PUMA were also upregulated by Taxol in p53 wild type cells. Conversely, when the wild type p53 was re-introduced into two different p53 null cancer cell lines, Taxol-induced apoptosis was enhanced. Among post-translational modifications that affect p53 stability and function, p53 acetylation, rather than phosphorylation, increased significantly in Taxol-treated cells. When acetylation was enhanced by anti-Sirt1 siRNA or an HDAC inhibitor, Taxol-induced apoptosis was enhanced, which was not observed in p53 null cells. When an acetylation-defective mutant of p53 was re-introduced to p53 null cells, apoptosis was partially reduced compared to the re-introduction of the wild type p53. Thus, p53 plays a pro-apoptotic role in Taxol-induced apoptosis and acetylation of p53 contributes to this pro-apoptotic function in response to Taxol in several human cancer cell lines, suggesting that enhancing acetylation of p53 could have potential implication for increasing the sensitivity of cancer cells to Taxol.

  2. 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.

  3. The role of p53 tumor suppressor gene in the suppression of teratogenesis. Mechanism of suppression in the embryonic stage by p53-dependent apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Nomoto, Satoshi; Ohtsu, Yamaaki; Norimura, Toshiyuki [University of Occupational and Environmental Health, Kitakyushu, Fukuoka (Japan)

    1996-12-01

    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.)

  4. 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.

  5. Long non-coding RNA NEAT1 is a transcriptional target of p53 and modulates p53-induced transactivation and tumor-suppressor function.

    Science.gov (United States)

    Idogawa, Masashi; Ohashi, Tomoko; Sasaki, Yasushi; Nakase, Hiroshi; Tokino, Takashi

    2017-03-14

    p53 is one of the most important tumor suppressor genes and the direct transcriptional targets of p53 must be explored to elucidate its functional mechanisms. Thus far, the p53 targets that have been primarily studied are protein-coding genes. Our previous study revealed that several long non-coding RNAs (lncRNAs) are direct transcriptional targets of p53, and knockdown of specific lncRNAs modulates p53-induced apoptosis. In this study, analysis of next-generation chromatin immunoprecipitation-sequencing (ChIP-seq) data for p53 revealed that the lncRNA NEAT1 is a direct transcriptional target of p53. The suppression of NEAT1 induction by p53 attenuates the inhibitory effect of p53 on cancer cell growth and also modulates gene transactivation, including that of many lncRNAs. Furthermore, low expression of NEAT1 is related to poor prognosis in several cancers. These results indicate that the induction of NEAT1 expression contributes to the tumor-suppressor function of p53 and suggest that p53 and NEAT1 constitute a transcriptional network contributing to various biological functions and tumor suppression. This article is protected by copyright. All rights reserved.

  6. A dynamic p53-mdm2 model with distributed delay

    Science.gov (United States)

    Horhat, Raluca; Horhat, Raul Florin

    2014-12-01

    Specific activator and repressor transcription factors which bind to specific regulator DNA sequences, play an important role in gene activity control. Interactions between genes coding such transcripion factors should explain the different stable or sometimes oscillatory gene activities characteristic for different tissues. In this paper, the dynamic P53-Mdm2 interaction model with distributed delays is investigated. Both weak and Dirac kernels are taken into consideration. For Dirac case, the Hopf bifurcation is investigated. Some numerical examples are finally given for justifying the theoretical results.

  7. Monocyte chemoattractant protein-1 induces endothelial cell apoptosis in vitro through a p53-dependent mitochondrial pathway

    Institute of Scientific and Technical Information of China (English)

    Xuan Zhang; Xiping Liu; Huifeng Shang; Yan Xu; Minzhang Qian

    2011-01-01

    The cystine-cystine (CC) chemokine monocyte chemoattractant protein-1 (MCP-1) has been established playing a pathogenic role in the development of atherosclerosis due to its chemotactic ability of leading monocytes to locate to subendothelia.Recent studies have revealed more MCP-1 functions other than chemotaxis.Here we reported that various concentrations (0.1-100 ng/ml) of MCP-1 induced human umbilical vein endothelial cell (HUVEC) strain CRL-1730 apoptosis,caspase-9 activation,and a couple of mitochondrial alterations.Moreover,MCP-1 upregulated p53 expression of HUVECs and the p53-specific inhibitor pifithrin-α(PFTα) rescued the MCP-1-induced apoptosis of HUVECs.Furthermore,PKC (protein kinase C) activation or inhibition might also affect HUVECs apoptosis induced by MCP-1.These findings together demonstrate that MCP-1 exerts direct proapoptotic effects on HUVECs in vitro via a p53-dependent mitochondrial pathway.

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

    Science.gov (United States)

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

    2016-09-20

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

  9. 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, M L B; Mishra, Durga Prasad

    2015-12-22

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

  10. Distinguishing Low-Risk Luminal A Breast Cancer Subtypes with Ki-67 and p53 Is More Predictive of Long-Term Survival.

    Science.gov (United States)

    Lee, Se Kyung; Bae, Soo Youn; Lee, Jun Ho; Lee, Hyun-Chul; Yi, Hawoo; Kil, Won Ho; Lee, Jeong Eon; Kim, Seok Won; Nam, Seok Jin

    2015-01-01

    Overexpression of p53 is the most frequent genetic alteration in breast cancer. Recently, many studies have shown that the expression of mutant p53 differs for each subtype of breast cancer and is associated with different prognoses. In this study, we aimed to determine the suitable cut-off value to predict the clinical outcome of p53 overexpression and its usefulness as a prognostic factor in each subtype of breast cancer, especially in luminal A breast cancer. Approval was granted by the Institutional Review Board of Samsung Medical Center. We analyzed a total of 7,739 patients who were surgically treated for invasive breast cancer at Samsung Medical Center between Dec 1995 and Apr 2013. Luminal A subtype was defined as ER&PR + and HER2- and was further subclassified according to Ki-67 and p53 expression as follows: luminal A (Ki-67-,p53-), luminal A (Ki-67+, p53-), luminal A (Ki-67 -, p53+) and luminal A (Ki-67+, p53+). Low-risk luminal A subtype was defined as negative for both Ki-67 and p53 (luminal A [ki-67-, p53-]), and others subtypes were considered to be high-risk luminal A breast cancer. A cut-off value of 10% for p53 was a good predictor of clinical outcome in all patients and luminal A breast cancer patients. The prognostic role of p53 overexpression for OS and DFS was only significant in luminal A subtype. The combination of p53 and Ki-67 has been shown to have the best predictive power as calculated by the area under curve (AUC), especially for long-term overall survival. In this study, we have shown that overexpression of p53 and Ki-67 could be used to discriminate low-risk luminal A subtype in breast cancer. Therefore, using the combination of p53 and Ki-67 expression in discriminating low-risk luminal A breast cancer may improve the prognostic power and provide the greatest clinical utility.

  11. Gain of oncogenic function of p53 mutants regulates E-cadherin expression uncoupled from cell invasion in colon cancer cells.

    Science.gov (United States)

    Roger, Lauréline; Jullien, Laurent; Gire, Véronique; Roux, Pierre

    2010-04-15

    Mutations in the p53 tumour suppressor gene are associated clinically with tumour progression and metastasis. Downregulation of the E-cadherin cell-cell adhesion molecule is a key event for epithelial to mesenchymal transition (EMT) in tumour progression. Here, we show that wild-type p53 induced to adopt a mutant conformation, and hot-spot p53 mutants, which are both transcriptionally inactive, downregulate E-cadherin expression in the colon carcinoma cell line HCT116. Downregulation of E-cadherin occurred concomitantly with the upregulation of Slug and Zeb-1, transcriptional factors known to repress E-cadherin gene expression. In addition, knockdown of Slug and Zeb-1 expression diminished p53-mediated E-cadherin repression. Knocking down endogenous mutant p53 in MDA-MB-231 and SW620 cancer cell lines lacking E-cadherin protein restored the expression of E-cadherin. Complete loss of E-cadherin expression in HCT116 cells induced morphological alterations along with upregulation of vimentin, a mesenchymal marker. These changes characteristic of the EMT phenotype were, however, not sufficient to confer invasiveness in a three-dimensional matrix. Downregulation of E-cadherin by mutant p53 was not required to promote the invasive phenotype induced by inactivation of p53. These findings indicate that independent control of E-cadherin expression and cell motility could be essential molecular events in p53 mutant-induced invasive phenotypes.

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

    Science.gov (United States)

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

    2017-03-10

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

  13. 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.

  14. Cross-regulation of protein stability by p53 and nuclear receptor SHP.

    Directory of Open Access Journals (Sweden)

    Zhihong Yang

    Full Text Available We report here a novel interplay between tumor suppressor p53 and nuclear receptor SHP that controls p53 and SHP stability. Overexpression of p53 causes rapid SHP protein degradation, which does not require the presence of Mdm2 and is mediated by the proteosome pathway. Overexpressing SHP alone does not affect p53 stability. However, SHP destabilizes p53 by augmentation of Mdm2 ubiquitin ligase activity toward p53. The single amino acid substitution in the SHP protein SHPK170R increases SHP binding to p53 relative to SHP wild-type, whereas SHPG171A variant shows a diminished p53 binding. As a result of the cross-regulation, the tumor suppressor function of p53 and SHP in inhibition of colon cancer growth is compromised. Our findings reveal a unique scenario for a cross-inhibition between two tumor suppressors to keep their expression and function in check.

  15. 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.

  16. Aurora B interacts with NIR-p53, leading to p53 phosphorylation in its DNA-binding domain and subsequent functional suppression.

    Science.gov (United States)

    Wu, Liming; Ma, Chi A; Zhao, Yongge; Jain, Ashish

    2011-01-21

    NIR (novel INHAT repressor) is a transcriptional co-repressor with inhibitor of histone acetyltransferase (INHAT) activity and has previously been shown to physically interact with and suppress p53 transcriptional activity and function. However, the mechanism by which NIR suppresses p53 is not completely understood. Using a proteomic approach, we have identified the Aurora kinase B as a novel binding partner of NIR. We show that Aurora B, NIR and p53 exist in a protein complex in which Aurora B binds to NIR, thus also indirectly associates with p53. Functionally, overexpression of Aurora B or NIR suppresses p53 transcriptional activity, and depletion of Aurora B or NIR causes p53-dependent apoptosis and cell growth arrest, due to the up-regulation of p21 and Bax. We then demonstrate that Aurora B phosphorylates multiple sites in the p53 DNA-binding domain in vitro, and this phosphorylation probably also occurs in cells. Importantly, the Aurora B-mediated phosphorylation on Ser(269) or Thr(284) significantly compromises p53 transcriptional activity. Taken together, these results provide novel insight into NIR-mediated p53 suppression and also suggest an additional way for p53 regulation.

  17. P53 but not cyclin E acts in a negative regulatory loop to control HER-2 expression in MCF-7 breast carcinoma cell line.

    Directory of Open Access Journals (Sweden)

    Hamed Montazeri

    2013-08-01

    Full Text Available Cyclin E, HER-2 and p53, are considered as major prognostic markers in breast cancer. As they are related in patho-clinical level, we aimed to check if they have any direct interaction on expression of each other. To study the effect of cyclin E on HER-2 expression, cell lines stably overexpressing cyclin E or its low molecular weight (LMW isoforms were generated. To understand the results of p53 silencing either alone or in combination with cyclin E overexpression, we created three different p53 stably knocked down cell lines. Protein expression was analyzed by western blot, HER-2 expression in the established cell lines were determined using SYBR green real time PCR and data analyzed by REST software. Results indicate that HER-2 expression is only downregulated following p53 silencing and none of cyclin E isoforms can alter its expression. The presence of cyclin E isoforms in p53 silenced clones also does not altered HER-2 expression. Given the fact that p53 degradation is increased by HER-2 overexpression, these data can draw a regulatory loop in which a non-mutated functional p53 and HER-2 can bidirectionally regulate the expression of these two genes. This study improves our understandings of these pathways and these proteins can be introduced either as a marker or as a target in cancer treatment.

  18. 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.

  19. 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.

  20. A dual role of p53 in the control of autophagy.

    Science.gov (United States)

    Tasdemir, Ezgi; Chiara Maiuri, M; Morselli, Eugenia; Criollo, Alfredo; D'Amelio, Marcello; Djavaheri-Mergny, Mojgan; Cecconi, Francesco; Tavernarakis, Nektarios; Kroemer, Guido

    2008-08-01

    Genotoxic stress can induce autophagy in a p53-dependent fashion and p53 can transactivate autophagy-inducing genes. We have observed recently that inactivation of p53 by deletion, depletion or inhibition can trigger autophagy. Thus, human and mouse cells subjected to knockout, knockdown or pharmacological inhibition of p53 manifest signs of autophagy such as depletion of p62/SQSTM1, LC3 lipidation, redistribution of GFP-LC3 in cytoplasmic puncta, and accumulation of autophagosomes and autolysosomes, both in vitro and in vivo. Inhibition of p53 causes autophagy in enucleated cells, indicating that the cytoplasmic, non-nuclear pool of p53 can regulate autophagy. Accordingly, retransfection of p53(-/-) cells with wild-type p53 as well as a p53 mutant that is excluded from the nucleus (due to the deletion of the nuclear localization sequence) can inhibit autophagy, whereas retransfection with a nucleus-restricted p53 mutant (in which the nuclear localization sequence has been deleted) does not inhibit autophagy. Several distinct autophagy inducers (e.g., starvation, rapamycin, lithium, tunicamycin and thapsigargin) stimulate the rapid degradation of p53. In these conditions, inhibition of the p53-specific E3 ubiquitin ligase HDM2 can avoid p53 depletion and simultaneously prevent the activation of autophagy. Moreover, a p53 mutant that lacks the HDM2 ubiquitinylation site and hence is more stable than wild-type p53 is particularly efficient in suppressing autophagy. In conclusion, p53 plays a dual role in the control of autophagy. On the one hand, nuclear p53 can induce autophagy through transcriptional effects. On the other hand, cytoplasmic p53 may act as a master repressor of autophagy.

  1. Bcl-2/Bax protein ratio predicts 5-fluorouracil sensitivity independently of p53 status

    OpenAIRE

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

    2000-01-01

    p53 tumour-suppressor gene is involved in cell growth control, arrest and apoptosis. Nevertheless cell cycle arrest and apoptosis induction can be observed in p53-defective cells after exposure to DNA-damaging agents such as 5-fluorouracil (5-FU) suggesting the importance of alternative pathways via p53-independent mechanisms. In order to establish relationship between p53 status, cell cycle arrest, Bcl-2/Bax regulation and 5-FU sensitivity, we examined p53 mRNA and protein expression and p53...

  2. Illuminating p53 function in cancer with genetically engineered mouse models

    OpenAIRE

    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...

  3. MdmX Protects p53 from Mdm2-Mediated Degradation

    OpenAIRE

    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...

  4. 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

  5. Resistance for Genotoxic Damage in Mesenchymal Stromal Cells Is Increased by Hypoxia but Not Generally Dependent on p53-Regulated Cell Cycle Arrest

    Science.gov (United States)

    Wieduwild, Elisabeth; Nerger, Katrin; Lambrecht, Nina; Schmoll, Hans-Joachim; Müller-Tidow, Carsten; Müller, Lutz Peter

    2017-01-01

    Adult stem cells including multipotent mesenchymal stromal cells (MSC) acquire a high amount of DNA-damage due to their prolonged lifespan. MSC may exert specific mechanisms of resistance to avoid loss of functional activity. We have previously shown that resistance of MSC is associated with an induction of p53 and proliferation arrest upon genotoxic damage. Hypoxia may also contribute to resistance in MSC due to the low oxygen tension in the niche. In this study we characterized the role of p53 and contribution of hypoxia in resistance of MSC to genotoxic damage. MSC exhibited increased resistance to cisplatin induced DNA-damage. This resistance was associated with a temporary G2/M cell cycle arrest, induction of p53- and p21-expression and reduced cyclin B / cdk1-levels upon subapoptotic damage. Resistance of MSC to cisplatin was increased at hypoxic conditions i. e. oxygen <0.5%. However, upon hypoxia the cisplatin-induced cell cycle arrest and expression of p53 and p21 were abrogated. MSC with shRNA-mediated p53 knock-down showed a reduced cell cycle arrest and increased cyclin B / cdk1 expression. However, this functional p53 knock down did not alter the resistance to cisplatin. In contrast to cisplatin, functional p53-knock-down increased the resistance of MSC to etoposide. We conclude that resistance of MSC to genotoxic damage is influenced by oxygen tension but is not generally dependent on p53. Thus, p53-dependent and p53-independent mechanisms of resistance are likely to contribute to the life-long functional activity of MSC in vivo. These findings indicate that hypoxia and different resistance pathways contribute to the phenotype that enables the prolonged lifespan of MSC. PMID:28081228

  6. 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...

  7. 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.

  8. p53在大肠癌中的表达及其临床意义%P53 EXPRESSION AND ITS CLINICAL SIGNIFICANCE INHUMAN COLORECTAL CARCINOM

    Institute of Scientific and Technical Information of China (English)

    雷厉

    2007-01-01

    目的 对大肠癌p53表达进行相关分析,探讨大肠癌中p53基因与肿瘤发生、发展的关系.方法 采用免疫组织化学S-P法,检测52例大肠癌中p53基因的表达.结果 p53表达与大肠癌浸润、转移有关(p<0.05);p53在大肠癌中表达与分化程度具有明显相关性;其与Dukes分期也具有明显相关性.结论 p53可作为临床判断大肠癌生物学行为的有用指标.

  9. 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.

  10. p300/CBP-mediated p53 acetylation is commonly induced by p53-activating agents and inhibited by MDM2

    OpenAIRE

    2001-01-01

    The tumor suppressor p53 is activated in response to many types of cellular and environmental insults via mechanisms involving post-translational modification. Here we demonstrate that, unlike phosphorylation, p53 invariably undergoes acetylation in cells exposed to a variety of stress-inducing agents including hypoxia, anti-metabolites, nuclear export inhibitor and actinomycin D treatment. In vivo, p53 acetylation is mediated by the p300 and CBP acetyltransferases. Overexpression of either p...

  11. High frequency of p53 intronic point mutations in laryngeal squamous cell carcinoma

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xu; LI Fucai; SONG Yutong; LI Yinghui; FU Weineng; XU Zhenming; SUN Kailai

    2004-01-01

    Intronic point mutations are rare and totally unknown for human laryngeal squamous cell carcinoma (LSCC). To explore the relationship of p53 gene intronic mutation to the development of human LSCC, DNA was extracted from both tumor tissues and matched normal tissues of 55 patients with LSCC in northeast of China. Polymerase chain reaction amplification-single strand conformational polymorphism (PCR-SSCP) combined with silver staining and DNA direct sequencing were used to detect mutations in exons 7~8 (p53E7 and p53E8) and introns 7~8 (p53I7 and p53I8) of p53 gene. The p53E7 mutation was detected in 17 out of 55 patients, and the p53I7 mutation in 21 patients. No mutation was found at p53E8 or p53I8 site. The difference between tumor group and paired normal group on the rates of both p53E7 and p53I7 mutations was statistically significant. The rate of p53I7 mutations in tumor tissue was higher than that of normal tissue, and so was that of p53E7. Sequence analysis revealed that most p53I7 mutations were at the nucleotides in the branch point sequence or the polypyrimidine tract in the 3′-splice acceptor site of the intron 7. The high incidence of p53 gene intronic mutation in LSCC indicates that genetic changes within the noncoding region of the p53 gene may serve as an alternative mechanism of activating the pathogenesis of human laryngeal squamous cell carcinoma. Mutations in the noncoding region of this gene should be further studied.

  12. Full p53 transcriptional activation potential is dispensable for tumor suppression in diverse lineages.

    Science.gov (United States)

    Jiang, Dadi; Brady, Colleen A; Johnson, Thomas M; Lee, Eunice Y; Park, Eunice J; Scott, Matthew P; Attardi, Laura D

    2011-10-11

    Over half of all human cancers, of a wide variety of types, sustain mutations in the p53 tumor suppressor gene. Although p53 limits tumorigenesis through the induction of apoptosis or cell cycle arrest, its molecular mechanism of action in tumor suppression has been elusive. The best-characterized p53 activity in vitro is as a transcriptional activator, but the identification of numerous additional p53 biochemical activities in vitro has made it unclear which mechanism accounts for tumor suppression. Here, we assess the importance of transcriptional activation for p53 tumor suppression function in vivo in several tissues, using a knock-in mouse strain expressing a p53 mutant compromised for transcriptional activation, p53(25,26). p53(25,26) is severely impaired for the transactivation of numerous classical p53 target genes, including p21, Noxa, and Puma, but it retains the ability to activate a small subset of p53 target genes, including Bax. Surprisingly, p53(25,26) can nonetheless suppress tumor growth in cancers derived from the epithelial, mesenchymal, central nervous system, and lymphoid lineages. Therefore, full transactivation of most p53 target genes is dispensable for p53 tumor suppressor function in a range of tissue types. In contrast, a transcriptional activation mutant that is completely defective for transactivation, p53(25,26,53,54), fails to suppress tumor development. These findings demonstrate that transcriptional activation is indeed broadly critical for p53 tumor suppressor function, although this requirement reflects the limited transcriptional activity observed with p53(25,26) rather than robust transactivation of a full complement of p53 target genes.

  13. 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.

  14. In vitro binding properties of tumor suppressor p53 with PUMA and NOXA.

    Science.gov (United States)

    Park, So Young; Jeong, Mi Suk; Jang, Se Bok

    2012-04-06

    The p53-upregulated modulator of apoptosis (Puma) and Noxa, are direct targets in p53-mediated apoptosis localized to the mitochondria. Tumor suppressor p53 induces apoptosis by transcriptional induction of Puma and Noxa, which encode proapoptotic BH3-only member Bcl-1 family proteins. However, at a molecular level, the mechanism of action of Puma and Noxa proteins remain poorly defined. In addition, there have been no reports on whether or not p53 directly interacts with Puma and Noxa, in vitro. Here, we provide evidence indicating that the DNA binding domain (DBD) of p53 directly interacted with the BH3 domains of human PUMA and NOXA. Our studies revealed that PUMA has a weak affinity for p53, but NOXA has significant affinity for p53. In this study, we developed a molecular docking model using homology modeling based on the structures of truncated p53, PUMA and NOXA. In addition, we investigated whether or not six mutants of p53 (K101A, T102A, L111A, D186A, G199A and S227A) were able to bind to PUMA and NOXA. Four structure-based mutations (T102A, L111A, D186A and G199A) disrupted the p53-PUMA/NOXA interaction. Our study suggested that these four mutations lowered the stability of the p53 DBD domain and induced aggregation of structurally destabilized p53, and thus disrupted the p53-PUMA/NOXA interaction.

  15. Modulation of Janus kinase 2 by p53 in ovarian cancer cells.

    Science.gov (United States)

    Reid, Thomas; Jin, Xiaohong; Song, Hui; Tang, Huai-Jing; Reynolds, R Kevin; Lin, Jiayuh

    2004-08-20

    The constitutive activation of the Janus kinase 2 (JAK2) and mutation of the p53 tumor suppressor are both detected in human cancer. We examined the potential regulation of JAK2 phosphorylation by wild-type (wt) p53 in human ovarian cancer cell lines, Caov-3 and MDAH2774, which harbor mutant form of p53 tumor suppressor gene and high levels of phosphorylated JAK2. The wt p53 gene was re-introduced into the cells using an adenovirus vector. In addition to wt p53, mutant p53 22/23, mutant p53-175, and NCV (negative control virus) were introduced into the cells in the control groups. Expression of wt p53, but not that of p53-175 mutant, diminished JAK2 tyrosine phosphorylation in MDAH2774 and Caov-3 cell lines. Expression of wt p53 or p53 22/23 mutant did not cause a reduction in the phosphorylation of unrelated protein kinases, ERK1 and ERK2 (ERK1/2). The inhibition of JAK2 tyrosine phosphorylation can be reversed by tyrosine phosphatase inhibitor, sodium orthovanadate. Protein tyrosine phosphatase 1-B levels increased with introduction of wt p53 and may be involved in the dephosphorylation of JAK2. These findings present a possible p53-dependent cellular process of modulating JAK2 tyrosine phosphorylation in ovarian cancer cell lines.

  16. 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

    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...

  17. p53在突变过程中的作用%Review of roles of p53 in the process of mutation

    Institute of Scientific and Technical Information of China (English)

    李奇慧; 董兆君

    2004-01-01

    肿瘤抑制基因p53在维持基因组稳定性和完整性方面发挥着重要作用.p53对突变机制和突变率都有较大的影响,p53功能缺失的各种体内外模型的突变率均有增加.突变的p53还可通过干扰包括凋亡在内的其他细胞程序而影响突变率.

  18. 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.

  19. Detection of point mutations in the p53 gene in bile for diagnosis of gallbladder cancer%从胆汁中检测p53基因突变诊断胆囊癌

    Institute of Scientific and Technical Information of China (English)

    金晓凌; 王炳生; 井清源

    2001-01-01

    Objective:To investigate the value of detection of point mutations in the p53 gene in bile for diagnosis of gallbladder cancer(GBC).Methods:Genetic alteration of the p53 gene was examined in bile specimens of 15 GBC cases and 10 cases of benign gallbladder disease using PCR(polymerase chain reaction)-SSCP(single-strand conformation polymorphism) combined with silver staining. Cytologic diagnosis was performed with all of bile specimens.Results:Sensitivity and specificity of bile cytologic diagnosis for GBC were 13% and 100% respectively. The p53 gene mutation was detected in nine of the 15 GBC cases examined(60%), and not in all of 10 benign bile specimens. The DNA analysis demonstrated the presence of p53 gene mutations in 8 cases of GBC with false-negative cytologic diagnosis.Conclusion:Detection of point mutations in the p53 gene in bile is highly specific for diagnosing GBC and may be a valuable diagnostic modality for GBC.%目的:探讨检测胆汁中p53基因突变对胆囊癌的诊断价值。方法:采用PCR-SSCP银染法,检测15例胆囊癌及10例良性胆囊疾病胆汁中p53基因的突变情况,并对胆汁标本进行细胞学检查。结果:胆汁细胞学检查诊断胆囊癌的阳性率为13%,特异性为100%。15例胆囊癌胆汁中有9例检出p53基因突变,占60%,其中8例细胞学检查为阴性;10例良性胆汁均未检出p53基因突变。结论:检测胆汁中p53基因突变,具有高度的特异性,可成为有价值的诊断胆囊癌的方法。

  20. 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.

  1. Bisindole-PBD regulates breast cancer cell proliferation via SIRT-p53 axis.

    Science.gov (United States)

    Sarma, Pranjal; Bag, Indira; Ramaiah, M Janaki; Kamal, Ahmed; Bhadra, Utpal; Pal Bhadra, Manika

    2015-01-01

    In a previous study we reported the role of potent bisindole-PBD conjugate as an inclusion in the arsenal of breast cancer therapeutics. In breast cancer cell proliferation, PI3K/AKT/mTOR pathway plays a crucial role by prosurvival mechanism that inhibits programmed cell death. Here, 2 breast cancer cells lines, MCF-7 and MDA-MB-231 were treated with Vorinostat (suberoylanilide hydroxamic acid / SAHA) and bisindole-PBD (5b). We have investigated the effect on PI3K/AKT/mTOR pathway and SIRT expression including epigenetic regulation. There was consistent decrease in the level of PI3K, AKT, mTOR proteins upon treatment of 5b in both MCF-7 and MDA-MB-231 cell lines compared to untreated controls. Treatment with caspase inhibitor (Q-VD-OPH) confirmed that the effect of 5b on PI3K signaling was ahead of apoptosis. Real time PCR and western blot analysis showed profound reduction in the mRNA and protein levels of SIRT1 and SIRT2. Molecular docking studies also supported the interaction of 5b with various amino acids of SIRT2 proteins. Treatment with 5b caused epigenetic changes that include increase of acetylated forms of p53, increase of histone acetylation at p21 promoter as well as decrease in methylation state of p21 gene. Compound 5b thus acts as SIRT inhibitor and cause p53 activation via inhibition of growth factor signaling and activation of p53 dependent apoptotic signaling. This present study focuses bisindole-PBD on epigenetic alteration putting 5b as a promising therapeutic tool in the realm of breast cancer research.

  2. Identification of Semaphorin3B as a Direct Target of p53

    Directory of Open Access Journals (Sweden)

    Kensuke Ochi

    2002-01-01

    Full Text Available A cDNA microarray analysis indicated that Semaphorin3B. (20Sema3B, a gene whose product is involved in axon guidance and axonal repulsion, is inducible by p53. Introduction of exogenous p53 into a glioblastoma cell line lacking wild-type p53. (20U373MG dramatically induced expression of Sema3B mRNA. An electrophoretic mobility shift assay and a reporter assay confirmed that a potential p53 binding site present in the promoter region had p53-dependent transcriptional activity. Expression of endogenous Sema3B was induced in response to genotoxic stresses caused by adriamycin treatment or UV irradiation in a p53-dependent manner. Ectopic expression of Sema3B in p53-defective cells reduced the number of colonies in colony formation assays. These results suggest that Sema3B might play some role in regulating cell growth as a mediator of p53 tumor- suppressor activity.

  3. 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

    2015-11-01

    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 Zn(2+) to Zn(2+)-deficient mutant p53.

  4. Constitutively activated ERK sensitizes cancer cells to doxorubicin: Involvement of p53-EGFR-ERK pathway

    Indian Academy of Sciences (India)

    RATNA KUMARI; SURBHI CHOUHAN; SNAHLATA SINGH; RISHI RAJ CHHIPA; AMRENDRA KUMAR AJAY; MANOJ KUMAR BHAT

    2017-03-01

    The tumour suppressor gene p53 is mutated in approximately 50% of the human cancers. p53 is involved in genotoxicstress-induced cellular responses. The role of EGFR and ERK in DNA-damage-induced apoptosis is well known. Weinvestigated the involvement of activation of ERK signalling as a consequence of non-functional p53, in sensitivity ofcells to doxorubicin. We performed cell survival assays in cancer cell lines with varying p53 status: MCF-7 (wild-typep53, WTp53), MDA MB-468 (mutant p53, MUTp53), H1299 (absence of p53, NULLp53) and an isogenic cell lineMCF-7As (WTp53 abrogated). Our results indicate that enhanced chemosensitivity of cells lacking wild-type p53function is because of elevated levels of EGFR which activates ERK. Additionally, we noted that independent of p53status, pERK contributes to doxorubicin-induced cell death.

  5. Mitochondrial localization of the low level p53 protein in proliferative cells

    Energy Technology Data Exchange (ETDEWEB)

    Ferecatu, Ioana; Bergeaud, Marie; Rodriguez-Enfedaque, Aida; Le Floch, Nathalie [Laboratoire de Genetique et Biologie Cellulaire - CNRS UMR 8159, Universite de Versailles Saint-Quentin-en-Yvelines, Versailles, France and Laboratoire de Genetique Moleculaire et Physiologique, Ecole Pratique des Hautes Etudes, Versailles (France); Oliver, Lisa [INSERM U601, Universite de Nantes, Faculte de Medecine, Nantes Cedex (France); Rincheval, Vincent; Renaud, Flore [Laboratoire de Genetique et Biologie Cellulaire - CNRS UMR 8159, Universite de Versailles Saint-Quentin-en-Yvelines, Versailles, France and Laboratoire de Genetique Moleculaire et Physiologique, Ecole Pratique des Hautes Etudes, Versailles (France); Vallette, Francois M. [INSERM U601, Universite de Nantes, Faculte de Medecine, Nantes Cedex (France); Mignotte, Bernard [Laboratoire de Genetique et Biologie Cellulaire - CNRS UMR 8159, Universite de Versailles Saint-Quentin-en-Yvelines, Versailles, France and Laboratoire de Genetique Moleculaire et Physiologique, Ecole Pratique des Hautes Etudes, Versailles (France); Vayssiere, Jean-Luc, E-mail: jean-luc.vayssiere@uvsq.fr [Laboratoire de Genetique et Biologie Cellulaire - CNRS UMR 8159, Universite de Versailles Saint-Quentin-en-Yvelines, Versailles, France and Laboratoire de Genetique Moleculaire et Physiologique, Ecole Pratique des Hautes Etudes, Versailles (France)

    2009-10-02

    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.

  6. p53 binds human telomeric G-quadruplex in vitro.

    Science.gov (United States)

    Adámik, Matej; Kejnovská, Iva; Bažantová, Pavla; Petr, Marek; Renčiuk, Daniel; Vorlíčková, Michaela; Brázdová, Marie

    2016-01-01

    The tumor suppressor protein p53 is a key factor in genome stability and one of the most studied of DNA binding proteins. This is the first study on the interaction of wild-type p53 with guanine quadruplexes formed by the human telomere sequence. Using electromobility shift assay and ELISA, we show that p53 binding to telomeric G-quadruplexes increases with the number of telomeric repeats. Further, p53 strongly favors G-quadruplexes folded in potassium over those formed in sodium, thus indicating the telomeric G-quadruplex conformational selectivity of p53. The presence of the quadruplex-stabilizing ligand, N-methyl mesoporphyrin IX (NMM), increases p53 recognition of G-quadruplexes in potassium. Using deletion mutants and selective p53 core domain oxidation, both p53 DNA binding domains are shown to be crucial for telomeric G-quadruplex recognition.

  7. 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

  8. 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.

  9. ATM and Chk2-dependent phosphorylation of MDMX contribute to p53 activation after DNA damage

    OpenAIRE

    Chen, Lihong; Gilkes, Daniele M.; Pan, Yu; Lane, William S; Chen, Jiandong

    2005-01-01

    The p53 tumor suppressor is activated after DNA damage to maintain genomic stability and prevent transformation. Rapid activation of p53 by ionizing radiation is dependent on signaling by the ATM kinase. MDM2 and MDMX are important p53 regulators and logical targets for stress signals. We found that DNA damage induces ATM-dependent phosphorylation and degradation of MDMX. Phosphorylated MDMX is selectively bound and degraded by MDM2 preceding p53 accumulation and activation. Reduction of MDMX...

  10. 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 examined by PCR, denaturing gradient gel electrophoresis (DGGE) and automated sequencing. P53 protein was detected by immunohistochemistry using monoclonal antibody DO-7. Results: p53 mutations were found in exons 5 through 9 in 21 of 34 patients (61.8%). Among them, 5 patients had mutation in liver metastasis but not in their primary tumors while in the other patients the same mutations were found in both primary and metastatic colorectal cancers. In no patients was p53 mutation exclusively found in the primary colorectal tumors. Moreover, additional mutation was detected in the metastatic lesions in two cases. Of the 37 mutations within the exons examined, 73% was missense mutation and 16% was nonsense mutation. There were 4 microinsertions. P53 protein was overexpressed in both primary and metastatic colorectal cancers with p53 gene mutations. The presence of p53 mutation significantly correlated with p53 protein accumulation (r=0.96, p< 0.001). However, in 4 patients with p53 nonsense mutation, immunohistochemical staining was negative. In three patients who showed no p53 mutation of the primary tumor, p53 protein was consistently overexpressed. Conclusion: In colorectal cancers, p53 gene mutation usually appears first in the primary tumor and maintains as such but is more prominent when metastasized to the liver. However, p53 gene mutation may occur only after being metastasized.Although p53 gene mutation and p53 protein overexpression correlate with each other, either parameter examined alone may lead to false positive or negative results.

  11. Interaction of hepatitis B virus with tumor suppressor gene p53: its significance and biological function

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The mechanism of the interaction of hepatitis B virus (HBV) with tumor suppressor p53 and its role in the hepatocarcinogenesis have been studied by PCR-directed sequencing, gel shift assays and in situ ultraviolet cross-linking assay. The biological function of the interaction of HBV with p53 gene was investigated by co-transfection of chloramphenicol acetyltransferase (CAT) reporter gene, p53 and HBV DNA, and quantitative PCR. Among the 16 primary hepatocellular carcinoma (PHC) samples, 13 were HBV-DNA positive,10 HBxAg positive and 9 p53 protein positive. The p53 gene point mutation was found in 5 samples, one of which had a G to T substitution located at codon 249. After analyzing the HBV genome by a computer program, a p53 response element binding sequence was found in HBV genome at upstream of enhancer I, from 1047 to 1059 nucleotides. This sequence could specifically bind to p53 protein, increase p53 protein accumulation in the PHC cells and stimulate the transactivating activity of p53 and HBV replication .The results also revealed that HBxAg could combine with p53 protein to form a complex in the cells and enhance CAT expression. Immunocytochemical staining showed that p53 protein complex was located in the cytoplasm and the process of p53 entry to nuclei was, in part, blocked. From our results, we conclude that the mutation of p53 gene at codon 249 is infrequent in HBV-associated PHC, the DNA-protein binding between HBV and p53, and the protein-protein binding between HBxAg and p53 might lead to the reduction or inactivation of p53 protein, which in turn resulting in HBV-associated hepatocarcinogenesis.

  12. p53 Downregulates Its Activating Vaccinia-Related Kinase 1, Forming a New Autoregulatory Loop

    OpenAIRE

    2006-01-01

    The stable accumulation of p53 is detrimental to the cell because it blocks cell growth and division. Therefore, increases in p53 levels are tightly regulated, mainly by its transcriptional target, mdm2, that downregulates p53. Elucidation of new signaling pathways requires the characterization of the members and the nature of their connection. Vaccinia-related kinase 1 (VRK1) contributes to p53 stabilization by partly interfering with its mdm2-mediated degradation, among other mechanisms; th...

  13. Control of p53 multimerization by Ubc13 is JNK-regulated

    OpenAIRE

    2009-01-01

    The p53 tumor suppressor protein is a key regulator of cellular proliferation and survival whose function is tightly regulated at the levels of transcription and protein stability. Here, we unveil the fine control of p53 on translationally active polysomes. We have previously reported that Ubc13, an E2 ubiquitin-conjugating enzyme, directly regulates p53 localization and transcriptional activity. We now demonstrate that the association of p53 and Ubc13 on polysomes requires ongoing translatio...

  14. Expression of p53 and CD44 in Canine Breast Tumor

    Institute of Scientific and Technical Information of China (English)

    LIU Yun; CUI Wen; CHENG Xi; FENG Xinchang

    2008-01-01

    The p53 and CD44 expression of 10 cases in canine breast tumor were examined utilizing immunohistochemical assay with rabbit anti-mouse polyclonal antibodies against p53 or CD44,respectively.The p53 expression was significantly higher in malignant than in benign breast tumor.The expression of CD44 was not significantly different in malignant breast cancer and benign breast tumor.This suggests that p53 can be used as an indicator for animal prognosis.

  15. Discrimination of p53 immunohistochemistry-positive tumors by its staining pattern in gastric cancer

    OpenAIRE

    2014-01-01

    Immunohistochemistry staining of p53 is a cheap and simple method to detect aberrant function of p53. However, there are some discrepancies between the result of immunohistochemistry staining and mutation analysis. This study attempted to find a new definition of p53 staining by its staining pattern. Immunohistochemistry staining of p53 and TP53 gene mutation analysis were performed in 148 gastric cancer patients. Also SNP-CGH array analysis was conducted to four cases. Positive staining of p...

  16. Mdm2 Splice isoforms regulate the p53/Mdm2/Mdm4 regulatory circuit via RING domain-mediated ubiquitination of p53 and Mdm4.

    Science.gov (United States)

    Fan, Chuandong; Wang, Xinjiang

    2017-02-06

    p53 is regulated by heterodimer E3 ligase Mdm2-Mdm4 via RING domain interaction. Mdm2 transcripts undergo alternative splicing, and Mdm2 splice isoforms are increased in cancer and induced by DNA damage. Although two major Mdm2 splice isoforms that do not bind to p53 were reported to impact the p53 pathway, the underlying biochemical mechanisms were not understood. Here, we show that these Mdm2 splice isoforms ubiquitinate Mdm2 and Mdm4 in vitro and regulate the activity of Mdm2-Mdm4 E3 complex in cells. The Mdm2 isoforms are capable of promoting p53 ubiquitination in the absence of Mdm2 or Mdm4. The two isoforms stimulate Mdm2 or Mdm4 activity for p53 ubiquitination in vitro and promote degradation of p53 and Mdm4 in cells. However, the Mdm2 isoforms have opposing effects on the steady-state p53 levels depending on the stoichiometric ratios of Mdm2, Mdm4 and the isoforms, causing either decreased or increased p53 levels in cells. Our data indicate that the Mdm2 splice isoforms can act as independent E3 ligases for p53 when Mdm2 and Mdm4 are absent, form potent heterodimer E3 ligases with either Mdm2 or Mdm4 for targeting p53 degradation, or act as inhibitory regulators of Mdm2-Mdm4 E3 ligase activity by downregulating Mdm4. These findings suggest that Mdm2 splice isoforms may play critical roles in the regulatory loop of p53/Mdm2-Mdm4 via a RING domain-mediated biochemical mechanism.

  17. The XPB and XPD DNA helicases are components of the p53-mediated apoptosis pathway.

    NARCIS (Netherlands)

    X.W. Wang (Xin Wei); W. Vermeulen (Wim); J.D. Coursen; M.K. Gibson (Michael); S.E. Lupold; K. Forrester; G. Xu; L. Elmore; H. Yeh; J.H.J. Hoeijmakers (Jan); C.C. Harris

    1996-01-01

    textabstractThe molecular pathway of p53-dependent apoptosis (programmed cell death) is poorly understood. Because p53 binds to the basal transcription-repair complex TFIIH and modulates its DNA helicase activities, we hypothesized that TFIIH DNA helicases XPB and XPD are members of the p53-mediated

  18. Loss of p53 Ser18 and Atm results in embryonic lethality without cooperation in tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Heather L Armata

    Full Text Available Phosphorylation at murine Serine 18 (human Serine 15 is a critical regulatory process for the tumor suppressor function of p53. p53Ser18 residue is a substrate for ataxia-telangiectasia mutated (ATM and ATM-related (ATR protein kinases. Studies of mice with a germ-line mutation that replaces Ser18 with Ala (p53(S18A mice have demonstrated that loss of phosphorylation of p53Ser18 leads to the development of tumors, including lymphomas, fibrosarcomas, leukemia and leiomyosarcomas. The predominant lymphoma is B-cell lymphoma, which is in contrast to the lymphomas observed in Atm(-/- animals. This observation and the fact that multiple kinases phosphorylate p53Ser18 suggest Atm-independent tumor suppressive functions of p53Ser18. Therefore, in order to examine p53Ser18 function in relationship to ATM, we analyzed the lifespan and tumorigenesis of mice with combined mutations in p53Ser18 and Atm. Surprisingly, we observed no cooperation in survival and tumorigenesis in compound p53(S18A and Atm(-/- animals. However, we observed embryonic lethality in the compound mutant animals. In addition, the homozygous p53Ser18 mutant allele impacted the weight of Atm(-/- animals. These studies examine the genetic interaction of p53Ser18 and Atm in vivo. Furthermore, these studies demonstrate a role of p53Ser18 in regulating embryonic survival and motor coordination.

  19. Genotoxic exposure: novel cause of selection for a functional ΔN-p53 isoform

    NARCIS (Netherlands)

    Melis, J.P.M.; Hoogervorst, E.M.; van Oostrom, C.T.M.; Zwart, E.; Breit, T.M.; Pennings, J.L.A.; de Vries, A.; van Steeg, H.

    2011-01-01

    The p53 gene is frequently mutated in cancers and it is vital for cell cycle control, homeostasis and carcinogenesis. We describe a novel p53 mutational spectrum, different to those generally observed in human and murine tumors. Our study shows a high prevalence of nonsense mutations in the p53 N te

  20. Translational regulation of p53 as a potential tumor therapy target

    NARCIS (Netherlands)

    B. Schumacher (Björn); A. Gartner (Anton)

    2006-01-01

    textabstractThe tumor suppressor p53 is a central player in apoptosis induction in response to oncogenic stimuli and DNA damage. As activation of p53 has been suggested as a prime strategy for future tumor therapy, inhibition of negative regulators of p53 activity would be a similarly desirable stra

  1. Suppression of p53 activity through the cooperative action of Ski and histone deacetylase SIRT1.

    Science.gov (United States)

    Inoue, Yasumichi; Iemura, Shun-ichiro; Natsume, Tohru; Miyazawa, Keiji; Imamura, Takeshi

    2011-02-25

    Ski was originally identified as an oncogene based on the fact that Ski overexpression transformed chicken and quail embryo fibroblasts. Consistent with these proposed oncogenic roles, Ski is overexpressed in various human tumors. However, whether and how Ski functions in mammalian tumorigenesis has not been fully investigated. Here, we show that Ski interacts with p53 and attenuates the biological functions of p53. Ski overexpression attenuated p53-dependent transactivation, whereas Ski knockdown enhanced the transcriptional activity of p53. Interestingly, Ski bound to the histone deacetylase SIRT1 and stabilized p53-SIRT1 interaction to promote p53 deacetylation, which subsequently decreased the DNA binding activity of p53. Consistent with the ability of Ski to inactivate p53, overexpressing Ski desensitized cells to genotoxic drugs and Nutlin-3, a small-molecule antagonist of Mdm2 that stabilizes p53 and activates the p53 pathway, whereas knocking down Ski increased the cellular sensitivity to these agents. These results indicate that Ski negatively regulates p53 and suggest that the p53-Ski-SIRT1 axis is an attractive target for cancer therapy.

  2. FGFR3 and P53 characterize alternative genetic pathways in the pathogenesis of urothelial cell carcinoma

    NARCIS (Netherlands)

    B.W. van Rhijn (Bas); Th.H. van der Kwast (Theo); A.N. Vis (André); W.J. Kirkels (Wim); E.R. Boeve; A.C. Jobsis; E.C. Zwarthoff (Ellen)

    2004-01-01

    textabstractFibroblast growth factor receptor 3 (FGFR3) and P53 mutations are frequently observed in bladder cancer. We here describe the distribution of FGFR3 mutations and P53 overexpression in 260 primary urothelial cell carcinomas. FGFR3 mutations were observed in 59% and P53 o

  3. Reverting p53 activation after recovery of cellular stress to resume with cell cycle progression.

    Science.gov (United States)

    Lazo, Pedro A

    2017-05-01

    The activation of p53 in response to different types of cellular stress induces several protective reactions including cell cycle arrest, senescence or cell death. These protective effects are a consequence of the activation of p53 by specific phosphorylation performed by several kinases. The reversion of the cell cycle arrest, induced by p53, is a consequence of the phosphorylated and activated p53, which triggers its own downregulation and that of its positive regulators. The different down-regulatory processes have a sequential and temporal order of events. The mechanisms implicated in p53 down-regulation include phosphatases, deacetylases, and protein degradation by the proteasome or autophagy, which also affect different p53 protein targets and functions. The necessary first step is the dephosphorylation of p53 to make it available for interaction with mdm2 ubiquitin-ligase, which requires the activation of phosphatases targeting both p53 and p53-activating kinases. In addition, deacetylation of p53 is required to make lysine residues accessible to ubiquitin ligases. The combined action of these downregulatory mechanisms brings p53 protein back to its basal levels, and cell cycle progression can resume if cells have overcome the stress or damage situation. The specific targeting of these down-regulatory mechanisms can be exploited for therapeutic purposes in cancers harbouring wild-type p53.

  4. Treating cancer when pRb and p53 cannot be reactivated.

    Science.gov (United States)

    Zhu, Liang

    2015-01-01

    Activation of oncoproteins and inactivation of tumor suppressors induces tumorigenesis. When these events happen upstream of pRb and p53, cancer therapies may initially succeed and then fail when pRb and p53 are activated and then re-inactivated. Therapies might succeed if they remain effective when pRb and p53 are genetically inactivated.

  5. Substrate phosphorylation and feedback regulation in JFK-promoted p53 destabilization.

    Science.gov (United States)

    Sun, Luyang; Shi, Lei; Wang, Feng; Huangyang, Peiwei; Si, Wenzhe; Yang, Jie; Yao, Zhi; Shang, Yongfeng

    2011-02-11

    The p53 tumor suppressor plays a central role in integrating cellular responses to various stresses. Tight regulation of p53 is thus essential for the maintenance of genome integrity and normal cell proliferation. Previously, we reported that JFK, the only Kelch domain-containing F-box protein in human, promotes ubiquitination and degradation of p53 and that unlike the other E3 ligases for p53, all of which possess an intrinsic ubiquitin ligase activity, JFK destabilizes p