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Sample records for p53 tumor suppressor

  1. 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.

  2. p53 tumor suppressor gene: significance in neoplasia - a review

    International Nuclear Information System (INIS)

    Alam, J.M.

    2000-01-01

    p53 is a tumor suppressor gene located on chromosome 17p13.1. Its function includes cell cycle control and apoptosis. Loss of p53 function, either due to decreased level or genetic transformation, is associated with loss of cell cycle control, decrease, apoptosis and genomic modification, such mutation of p53 gene is now assessed and the indicator of neoplasia of cancer of several organs and cell types, p53 has demonstrated to have critical role in defining various progressive stages of neoplasia, therapeutic strategies and clinical application. The present review briefly describes function of p53 in addition to its diagnostic and prognostic significance in detecting several types of neoplasia. (author)

  3. Combining Oncolytic Virotherapy with p53 Tumor Suppressor Gene Therapy

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    Christian Bressy

    2017-06-01

    Full Text Available Oncolytic virus (OV therapy utilizes replication-competent viruses to kill cancer cells, leaving non-malignant cells unharmed. With the first U.S. Food and Drug Administration-approved OV, dozens of clinical trials ongoing, and an abundance of translational research in the field, OV therapy is poised to be one of the leading treatments for cancer. A number of recombinant OVs expressing a transgene for p53 (TP53 or another p53 family member (TP63 or TP73 were engineered with the goal of generating more potent OVs that function synergistically with host immunity and/or other therapies to reduce or eliminate tumor burden. Such transgenes have proven effective at improving OV therapies, and basic research has shown mechanisms of p53-mediated enhancement of OV therapy, provided optimized p53 transgenes, explored drug-OV combinational treatments, and challenged canonical roles for p53 in virus-host interactions and tumor suppression. This review summarizes studies combining p53 gene therapy with replication-competent OV therapy, reviews preclinical and clinical studies with replication-deficient gene therapy vectors expressing p53 transgene, examines how wild-type p53 and p53 modifications affect OV replication and anti-tumor effects of OV therapy, and explores future directions for rational design of OV therapy combined with p53 gene therapy.

  4. Paracrine Apoptotic Effect of p53 Mediated by Tumor Suppressor Par-4

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    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.

  5. 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.

  6. Transcriptional Inhibition of the Human Papilloma Virus Reactivates Tumor Suppressor p53 in Cervical Carcinoma Cells

    Science.gov (United States)

    Kochetkov, D. V.; Ilyinskaya, G. V.; Komarov, P. G.; Strom, E.; Agapova, L. S.; Ivanov, A. V.; Budanov, A. V.; Frolova, E. I.; Chumakov, P. M.

    2009-01-01

    Inactivation of tumor suppressor p53 accompanies the majority of human malignancies. Restoration of p53 function causes death of tumor cells and is potentially suitable for gene therapy of cancer. In cervical carcinoma, human papilloma virus (HPV) E6 facilitates proteasomal degradation of p53. Hence, a possible approach to p53 reactivation is the use of small molecules suppressing the function of viral proteins. HeLa cervical carcinoma cells (HPV-18) with a reporter construct containing the b-galactosidase gene under the control of a p53-responsive promoter were used as a test system to screen a library of small molecules for restoration of the transcriptional activity of p53. The effect of the two most active compounds was studied with cell lines differing in the state of p53-dependent signaling pathways. The compounds each specifically activated p53 in cells expressing HPV-18 and, to a lesser extent, HPV-16 and exerted no effect on control p53-negative cells or cells with the intact p53-dependent pathways. Activation of p53 in cervical carcinoma cells was accompanied by induction of p53-dependent CDKN1 (p21), inhibition of cell proliferation, and induction of apoptosis. In addition, the two compounds dramatically decreased transcription of the HPV genome, which was assumed to cause p53 reactivation. The compounds were low-toxic for normal cells and can be considered as prototypes of new anticancer drugs. PMID:17685229

  7. Tumor Suppressor p53 Stimulates the Expression of Epstein-Barr Virus Latent Membrane Protein 1.

    Science.gov (United States)

    Wang, Qianli; Lingel, Amy; Geiser, Vicki; Kwapnoski, Zachary; Zhang, Luwen

    2017-10-15

    Epstein-Barr virus (EBV) is associated with multiple human malignancies. EBV latent membrane protein 1 (LMP1) is required for the efficient transformation of primary B lymphocytes in vitro and possibly in vivo The tumor suppressor p53 plays a seminal role in cancer development. In some EBV-associated cancers, p53 tends to be wild type and overly expressed; however, the effects of p53 on LMP1 expression is not clear. We find LMP1 expression to be associated with p53 expression in EBV-transformed cells under physiological and DNA damaging conditions. DNA damage stimulates LMP1 expression, and p53 is required for the stimulation. Ectopic p53 stimulates endogenous LMP1 expression. Moreover, endogenous LMP1 blocks DNA damage-mediated apoptosis. Regarding the mechanism of p53-mediated LMP1 expression, we find that interferon regulatory factor 5 (IRF5), a direct target of p53, is associated with both p53 and LMP1. IRF5 binds to and activates a LMP1 promoter reporter construct. Ectopic IRF5 increases the expression of LMP1, while knockdown of IRF5 leads to reduction of LMP1. Furthermore, LMP1 blocks IRF5-mediated apoptosis in EBV-infected cells. All of the data suggest that cellular p53 stimulates viral LMP1 expression, and IRF5 may be one of the factors for p53-mediated LMP1 stimulation. LMP1 may subsequently block DNA damage- and IRF5-mediated apoptosis for the benefits of EBV. The mutual regulation between p53 and LMP1 may play an important role in EBV infection and latency and its related cancers. IMPORTANCE The tumor suppressor p53 is a critical cellular protein in response to various stresses and dictates cells for various responses, including apoptosis. This work suggests that an Epstein-Bar virus (EBV) principal viral oncogene is activated by cellular p53. The viral oncogene blocks p53-mediated adverse effects during viral infection and transformation. Therefore, the induction of the viral oncogene by p53 provides a means for the virus to cope with infection and

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

    OpenAIRE

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

    1992-01-01

    Germ-line mutations in the p53 tumor suppressor gene have been observed in patients with Li-Fraumeni syndrome, brain tumors, second malignancies, and breast cancers. It is unclear whether all of these mutations have inactivated p53 and thereby provide an increased risk for cancer. Therefore, it is necessary to establish the biological significance of these germ-line mutations by the functional and structural analysis of the resulting mutant p53 proteins. We analyzed the ability of seven germ-...

  9. Long Non-coding RNA, PANDA, Contributes to the Stabilization of p53 Tumor Suppressor Protein.

    Science.gov (United States)

    Kotake, Yojiro; Kitagawa, Kyoko; Ohhata, Tatsuya; Sakai, Satoshi; Uchida, Chiharu; Niida, Hiroyuki; Naemura, Madoka; Kitagawa, Masatoshi

    2016-04-01

    P21-associated noncoding RNA DNA damage-activated (PANDA) is induced in response to DNA damage and represses apoptosis by inhibiting the function of nuclear transcription factor Y subunit alpha (NF-YA) transcription factor. Herein, we report that PANDA affects regulation of p53 tumor-suppressor protein. U2OS cells were transfected with PANDA siRNAs. At 72 h post-transfection, cells were subjected to immunoblotting and quantitative reverse transcription-polymerase chain reaction. Depletion of PANDA was associated with decreased levels of p53 protein, but not p53 mRNA. The stability of p53 protein was markedly reduced by PANDA silencing. Degradation of p53 protein by silencing PANDA was prevented by treatment of MG132, a proteasome inhibitor. Moreover, depletion of PANDA prevented accumulation of p53 protein, as a result of DNA damage, induced by the genotoxic agent etoposide. These results suggest that PANDA stabilizes p53 protein in response to DNA damage, and provide new insight into the regulatory mechanisms of p53. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  10. Effect of hydroxyurea on the promoter occupancy profiles of tumor suppressor p53 and p73

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    Lu Xin

    2009-06-01

    Full Text Available Abstract Background The p53 tumor suppressor and its related protein, p73, share a homologous DNA binding domain, and mouse genetics studies have suggested that they have overlapping as well as distinct biological functions. Both p53 and p73 are activated by genotoxic stress to regulate an array of cellular responses. Previous studies have suggested that p53 and p73 independently activate the cellular apoptotic program in response to cytotoxic drugs. The goal of this study was to compare the promoter-binding activity of p53 and p73 at steady state and after genotoxic stress induced by hydroxyurea. Results We employed chromatin immunoprecipitation, the NimbleGen promoter arrays and a model-based algorithm for promoter arrays to identify promoter sequences enriched in anti-p53 or anti-p73 immunoprecipitates, either before or after treatment with hydroxyurea, which increased the expression of both p53 and p73 in the human colon cancer cell line HCT116-3(6. We calculated a model-based algorithm for promoter array score for each promoter and found a significant correlation between the promoter occupancy profiles of p53 and p73. We also found that after hydroxyurea treatment, the p53-bound promoters were still bound by p73, but p73 became associated with additional promoters that that did not bind p53. In particular, we showed that hydroxyurea induces the binding of p73 but not p53 to the promoter of MLH3, which encodes a mismatch repair protein, and causes an up-regulation of the MLH3 mRNA. Conclusion These results suggest that hydroxyurea exerts differential effects on the promoter-binding functions of p53 and p73 and illustrate the power of model-based algorithm for promoter array in the analyses of promoter occupancy profiles of highly homologous transcription factors.

  11. Electrochemical sensing of tumor suppressor protein p53-deoxyribonucleic acid complex stability at an electrified interface

    Czech Academy of Sciences Publication Activity Database

    Paleček, Emil; Černocká, Hana; Ostatná, Veronika; Navrátilová, Lucie; Brázdová, Marie

    2014-01-01

    Roč. 828, MAY2014 (2014), s. 1-8 ISSN 0003-2670 R&D Projects: GA ČR(CZ) GAP301/11/2055; GA ČR(CZ) GA13-00956S; GA ČR(CZ) GA13-36108S Institutional support: RVO:68081707 Keywords : Deoxyribonucleic acid-protein binding * Tumor suppressor protein p53 * Electrochemical sensing Subject RIV: BO - Biophysics Impact factor: 4.513, year: 2014

  12. Polymorphism of the p53 tumor suppressor gene is associated with susceptibility to uterine leiomyoma.

    Science.gov (United States)

    Denschlag, Dominik; Bettendorf, Herta; Watermann, Dirk; Keck, Christoph; Tempfer, Clemens; Pietrowski, Detlef

    2005-07-01

    To evaluate the association between the presence of uterine leiomyoma and two single nuclear polymorphisms of the p53 tumor suppressor and the angiopoietin-2 (ANGPT2) genes. Prospective case control study. Academic research institution. One hundred thirty-two women with clinically and surgically diagnosed uterine leiomyomas and 280 controls. Peripheral venous puncture. Genotyping was performed by polymerase chain reaction-based amplification of the Arg and Pro variants at codon 72 of the p53 gene and by restriction fragment length polymorphism analysis of the G/G and G/A alleles in exon 4 of the ANGPT2 gene. Comparing women with uterine leiomyomas and controls, no statistically significant difference with respect to allele frequency and genotype distribution were ascertained for the ANGPT2 polymorphism (P=.2 and P=.5, respectively). However, for the p53 tumor suppressor gene polymorphism, statistically significant differences in terms of a higher Pro allele frequency and a higher prevalence of the Pro/Pro genotype among women with uterine leiomyoma (32.0% vs. 16.0%, respectively, and 21.3% vs. 4.7%, respectively) were ascertained (P=.001, OR 1.74; 95% CI 1.24-2.45, P=.001; OR 3.84, 95% CI 1.81-8.14; respectively). Carriage of the p53 polymorphism at codon 72 predicts the susceptibility to leiomyoma in a Caucasian population and may contribute to the pathogenesis of uterine leiomyoma.

  13. Requirement of the ATM/p53 tumor suppressor pathway for glucose homeostasis.

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    Armata, Heather L; Golebiowski, Diane; Jung, Dae Young; Ko, Hwi Jin; Kim, Jason K; Sluss, Hayla K

    2010-12-01

    Ataxia telangiectasia (A-T) patients can develop multiple clinical pathologies, including neuronal degeneration, an elevated risk of cancer, telangiectasias, and growth retardation. Patients with A-T can also exhibit an increased risk of insulin resistance and type 2 diabetes. The ATM protein kinase, the product of the gene mutated in A-T patients (Atm), has been implicated in metabolic disease, which is characterized by insulin resistance and increased cholesterol and lipid levels, blood pressure, and atherosclerosis. ATM phosphorylates the p53 tumor suppressor on a site (Ser15) that regulates transcription activity. To test whether the ATM pathway that regulates insulin resistance is mediated by p53 phosphorylation, we examined insulin sensitivity in mice with a germ line mutation that replaces the p53 phosphorylation site with alanine. The loss of p53 Ser18 (murine Ser15) led to increased metabolic stress, including severe defects in glucose homeostasis. The mice developed glucose intolerance and insulin resistance. The insulin resistance correlated with the loss of antioxidant gene expression and decreased insulin signaling. N-Acetyl cysteine (NAC) treatment restored insulin signaling in late-passage primary fibroblasts. The addition of an antioxidant in the diet rendered the p53 Ser18-deficient mice glucose tolerant. This analysis demonstrates that p53 phosphorylation on an ATM site is an important mechanism in the physiological regulation of glucose homeostasis.

  14. Effect of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) on the growth and radiotherapeutic sensitivity of human lymphoma cell lines

    International Nuclear Information System (INIS)

    Yu Zeyang; Fan Wo; Li Dongqing; Zhu Ran; Wang Yongqing; Wu Jinchang

    2008-01-01

    Objective: To explore the inhibitory effect and radiation sensitization of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) on human lymphoma cell lines. Methods: Human lymphoma cell lines Raji and Daudi were treated with rAd-p53, radiation therapy and combined treatment, respectively. The cell growth inhibition was assessed by MTT. The p53 protein expression was detected by Western blotting, and p53 mRNA was detected by BT-PCB. Results: The MTT results showed that the inhibitory effect and radiosensitivity enhancement of rAd-p53 on human lymphoma cell lines were not obvious [Raji: (27.5±4.1)%; Daudi: (28.1±1.6)%]. The results of Western blotting and BT-PCB showed that extrinsic p53 protein and p53 mRNA were expressed to some degree, but not at high-level. In addition, the results didn't demonstrate obvious radiosensitivity enhancement. Conclusions: The role of inhibition and radiosensitivity enhancement of rAd-p53 was not significant on human lymphoma cell lines. (authors)

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

    Science.gov (United States)

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

    1992-07-15

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

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

    Science.gov (United States)

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

    1992-01-01

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

  17. Overexpression of the p53 tumor suppressor gene product in primary lung adenocarcinomas is associated with cigarette smoking

    NARCIS (Netherlands)

    Westra, W. H.; Offerhaus, G. J.; Goodman, S. N.; Slebos, R. J.; Polak, M.; Baas, I. O.; Rodenhuis, S.; Hruban, R. H.

    1993-01-01

    Mutations in the p53 tumor suppressor gene are frequently observed in primary lung adenocarcinomas, suggesting that these mutations are critical events in the malignant transformation of airway cells. These mutations are often associated with stabilization of the p53 gene product, resulting in the

  18. Restoration of tumor suppressor miR-34 inhibits human p53-mutant gastric cancer tumorspheres

    International Nuclear Information System (INIS)

    Ji, Qing; Hao, Xinbao; Meng, Yang; Zhang, Min; DeSano, Jeffrey; Fan, Daiming; Xu, Liang

    2008-01-01

    MicroRNAs (miRNAs), some of which function as oncogenes or tumor suppressor genes, are involved in carcinogenesis via regulating cell proliferation and/or cell death. MicroRNA miR-34 was recently found to be a direct target of p53, functioning downstream of the p53 pathway as a tumor suppressor. miR-34 targets Notch, HMGA2, and Bcl-2, genes involved in the self-renewal and survival of cancer stem cells. The role of miR-34 in gastric cancer has not been reported previously. In this study, we examined the effects of miR-34 restoration on p53-mutant human gastric cancer cells and potential target gene expression. Human gastric cancer cells were transfected with miR-34 mimics or infected with the lentiviral miR-34-MIF expression system, and validated by miR-34 reporter assay using Bcl-2 3'UTR reporter. Potential target gene expression was assessed by Western blot for proteins, and by quantitative real-time RT-PCR for mRNAs. The effects of miR-34 restoration were assessed by cell growth assay, cell cycle analysis, caspase-3 activation, and cytotoxicity assay, as well as by tumorsphere formation and growth. Human gastric cancer Kato III cells with miR-34 restoration reduced the expression of target genes Bcl-2, Notch, and HMGA2. Bcl-2 3'UTR reporter assay showed that the transfected miR-34s were functional and confirmed that Bcl-2 is a direct target of miR-34. Restoration of miR-34 chemosensitized Kato III cells with a high level of Bcl-2, but not MKN-45 cells with a low level of Bcl-2. miR-34 impaired cell growth, accumulated the cells in G1 phase, increased caspase-3 activation, and, more significantly, inhibited tumorsphere formation and growth. Our results demonstrate that in p53-deficient human gastric cancer cells, restoration of functional miR-34 inhibits cell growth and induces chemosensitization and apoptosis, indicating that miR-34 may restore p53 function. Restoration of miR-34 inhibits tumorsphere formation and growth, which is reported to be

  19. Tumor suppressor p53 biology, its role in radioresponse and the analysis of p53 mutation/expression among Filipino breast cancers

    International Nuclear Information System (INIS)

    Deocaris, Custer C.

    2004-01-01

    Ionizing radiation remains one of the most effective tools for the treatment of breast cancer. It combines properties of a potent DNA-damaging agent and high degree of spatial specificity to the target tissue. Nonetheless, there remain considerable differences in the outcome for treatment of tumors of differing histological type treated by radiotherapy. The identification of predictive indicators of radiosensitivity is crucial for selecting patients suited for preoperative radiotherapy as well as those unwarranted for postoperative treatments. To improve prognostication, numerous genes involved in the breast carcinogenesis have been studied and thus far over the last decade several multi-center researches converge on the role of tumor suppressor p53 in tumor biology. The p53 gene is located on the short arm of chromosome 17 and encodes a 53-kd nuclear protein, p-53, also referred to as 'the guardian of the genome', it orchestrates multiple cellular processes such as cell growth control, DNA repair and programmed cell death. During radiotherapy, genotoxic damage induces p53 overexpression in order to control the rate of proliferating damaged cells, repair damage or induce the apoptotic pathway. Its molecular inactivation in a tumor cell, typically by a point mutation, leads to chemo/radio resistance due to the inability of the molecule to trigger p53-dependent programmed cell death

  20. Pharmacological activation of tumor suppressor, wild-type p53 as a promising strategy to fight cancer

    Directory of Open Access Journals (Sweden)

    Alicja Sznarkowska

    2010-08-01

    Full Text Available A powerful tumor suppressorp53 protein is a transcription factor which plays a critical role in eliciting cellular responses to a variety of stress signals, including DNA damage, hypoxia and aberrant proliferative signals, such as oncogene activation. Since its discovery thirty one years ago, p53 has been connected to tumorigenesis as it accumulates in the transformed tumor cells. Cellular stress induces stabilization of p53 and promotes, depending on the stress level, cell cycle arrest or apoptosis in the irreversibly damaged cells. The p53 protein is found inactive in more than 50�0of human tumors either by enhanced proteasomal degradation or due to the inactivating point mutations in its gene. Numerous data indicate that low molecular weight compounds, identified by molecular modeling or in the functional, cell-based assays, efficiently activate non-mutated p53 in cancer cells which in consequence leads to their elimination due to p53-dependent apoptosis. In this work we describe the structure and cellular function of p53 as well as the latest discoveries on the compounds with high anti-tumor activities aiming at reactivation of the tumor suppressor function of p53.

  1. Influence of anticancer drugs on interactions of tumor suppressor protein p53 with DNA

    Czech Academy of Sciences Publication Activity Database

    Pivoňková, Hana; Němcová, Kateřina; Brázdová, Marie; Kašpárková, Jana; Brabec, Viktor; Fojta, Miroslav

    2005-01-01

    Roč. 272, Suppl. 1 (2005), s. 562 ISSN 1474-3833. [FEBS Congress /30./ and IUBMB Conference /9./. 02.07.2005-07.07.2005, Budapest] R&D Projects: GA MZd(CZ) NC7574 Institutional research plan: CEZ:AV0Z50040507 Keywords : tumour suppressor protein p53 * anticancer drugs * interaction with DNA Subject RIV: BO - Biophysics

  2. Effect of recombinant adenovirus encoding human p53 tumor suppressor gene combined with radiation therapy on human lymphoma cells lines

    International Nuclear Information System (INIS)

    Yu Zeyang; Fan Wo; Li Dongqing; Zhu Ran; Wan Jianmei; Wang Yongqing; Wu Jinchang

    2008-01-01

    This paper analyzes the inhibitory effect and radiation sensitization of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) on human lymphoma cell lines. Human lymphoma cell lines were treated with rAd-p53, radiation therapy and combined treatment, respectively. The cell growth inhibition was assessed by MTF. The cell cycle and apoptosis were detected by flow cytometry, and the p53 protein expression was detected by Western blotting. The results showed that extrinsic p53 gene have expressed to some degree, but not at high level. The role of inhibition and radiation sensitivity of rAd-p53 was not significant to human lymphoma cell lines. (authors)

  3. SIGNALING TO THE P53 TUMOR SUPPRESSOR THROUGH PATHWAYS ACTIVATED BY GENOTOXIC AND NON-GENOTOXIC STRESSES.

    Energy Technology Data Exchange (ETDEWEB)

    ANDERSON,C.W.APPELLA,E.

    2002-07-01

    The p53 tumor suppressor is a tetrameric transcription factor that is post-translational modified at {approx}18 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 the posttranslational modifications to p53 and the pathways that produce them in response to both genotoxic and non-genotoxic stresses.

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

    Science.gov (United States)

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

    2009-01-01

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

  5. DNA damage tolerance pathway involving DNA polymerase ι and the tumor suppressor p53 regulates DNA replication fork progression.

    Science.gov (United States)

    Hampp, Stephanie; Kiessling, Tina; Buechle, Kerstin; Mansilla, Sabrina F; Thomale, Jürgen; Rall, Melanie; Ahn, Jinwoo; Pospiech, Helmut; Gottifredi, Vanesa; Wiesmüller, Lisa

    2016-07-26

    DNA damage tolerance facilitates the progression of replication forks that have encountered obstacles on the template strands. It involves either translesion DNA synthesis initiated by proliferating cell nuclear antigen monoubiquitination or less well-characterized fork reversal and template switch mechanisms. Herein, we characterize a novel tolerance pathway requiring the tumor suppressor p53, the translesion polymerase ι (POLι), the ubiquitin ligase Rad5-related helicase-like transcription factor (HLTF), and the SWI/SNF catalytic subunit (SNF2) translocase zinc finger ran-binding domain containing 3 (ZRANB3). This novel p53 activity is lost in the exonuclease-deficient but transcriptionally active p53(H115N) mutant. Wild-type p53, but not p53(H115N), associates with POLι in vivo. Strikingly, the concerted action of p53 and POLι decelerates nascent DNA elongation and promotes HLTF/ZRANB3-dependent recombination during unperturbed DNA replication. Particularly after cross-linker-induced replication stress, p53 and POLι also act together to promote meiotic recombination enzyme 11 (MRE11)-dependent accumulation of (phospho-)replication protein A (RPA)-coated ssDNA. These results implicate a direct role of p53 in the processing of replication forks encountering obstacles on the template strand. Our findings define an unprecedented function of p53 and POLι in the DNA damage response to endogenous or exogenous replication stress.

  6. miR-339-5p regulates the p53 tumor-suppressor pathway by targeting MDM2

    DEFF Research Database (Denmark)

    Jansson, M D; Djodji Damas, Nkerorema; Lees, M

    2014-01-01

    MicroRNAs (miRNAs) regulate many key cancer-relevant pathways and may themselves possess oncogenic or tumor-suppressor functions. Consequently, miRNA dysregulation has been shown to be a prominent feature in many human cancers. The p53 tumor suppressor acts as a negative regulator of cell prolife...... tumor cells. Furthermore, we show that a negative correlation between miR-339-5p and MDM2 expression exists in human cancer, implying that the interaction is important for cancer development.Oncogene advance online publication, 2 June 2014; doi:10.1038/onc.2014.130....

  7. The induction of a tumor suppressor gene (p53) expression by low-dose radiation and its biological meaning

    International Nuclear Information System (INIS)

    Ohnishi, Takeo

    1997-01-01

    I report the induced accumulation of wild-type p53 protein of a tumor suppressor gene within 12 h in various organs of rats exposed to X-ray irradiation at low doses (10-50 cGy). The levels of p53 in some organs of irradiated rats were increased about 2- to 3-fold in comparison with the basal p53 levels in non-irradiated rats. Differences in the levels of p53 induction after low-dose X-ray irradiation were observed among the small intestine, bone marrow, brain, liver, adrenal gland, spleen, hypophysis and skin. In contrast, there was no obvious accumulation of p53 protein in the testis and ovary. Thus, the induction of cellular p.53 accumulation by low-dose X-ray irradiation in rats seems to be organ-specific. I consider that cell type, and interactions with other signal transduction pathways of the hormone system, immune system and nervous system may contribute to the variable induction of p53 by low-dose X-ray irradiation. I discussed the induction of p53 by radiation and its biological meaning from an aspect of the defense system for radiation-induced cancer. (author)

  8. Epigenetic identification of ZNF545 as a functional tumor suppressor in multiple myeloma via activation of p53 signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Yu [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Zhan, Qian [The Center for Clinical Molecular Medical Detection, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Xu, Hongying [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Li, Lili; Li, Chen [Cancer Epigenetics Laboratory, Department of Clinical Oncology, Sir YK Pao Center for Cancer and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong and CUHK Shenzhen Research Institute (Hong Kong); Xiao, Qian; Xiang, Shili; Hui, Tianli [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Xiang, Tingxiu, E-mail: larissaxiang@163.com [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Ren, Guosheng, E-mail: rengs726@126.com [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China)

    2016-06-10

    The KRAB–zinc-finger protein ZNF545 was recently identified as a potential suppressor gene in several tumors. However, the regulatory mechanisms of ZNF545 in tumorigenesis remain unclear. In this study, we investigated the expression and roles of ZNF545 in multiple myeloma (MM). ZNF545 was frequently downregulated in MM tissues compared with non-tumor bone marrow tissues. ZNF545 expression was silenced by promoter methylation in MM cell lines, and could be restored by demethylation treatment. ZNF545 methylation was detected in 28.3% of MM tissues, compared with 4.3% of normal bone marrow tissues. ZNF545 transcriptionally activated the p53 signaling pathway but had no effect on Akt in MM, whereas ectopic expression of ZNF545 in silenced cells suppressed their proliferation and induced apoptosis. We therefore identified ZNF545 as a novel tumor suppressor inhibiting tumor growth through activation of the p53 pathway in MM. Moreover, tumor-specific methylation of ZNF545 may represent an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. -- Highlights: •Downregulated ZNF545 in MM tissues and cell lines and ectopic expression of ZNF545 suppresses tumor growth. •Tumor-specific methylation of ZNF545 represents an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. •ZNF545 exerts its tumor suppressive effects via transcriptional activating p53 pathway.

  9. Epigenetic identification of ZNF545 as a functional tumor suppressor in multiple myeloma via activation of p53 signaling pathway

    International Nuclear Information System (INIS)

    Fan, Yu; Zhan, Qian; Xu, Hongying; Li, Lili; Li, Chen; Xiao, Qian; Xiang, Shili; Hui, Tianli; Xiang, Tingxiu; Ren, Guosheng

    2016-01-01

    The KRAB–zinc-finger protein ZNF545 was recently identified as a potential suppressor gene in several tumors. However, the regulatory mechanisms of ZNF545 in tumorigenesis remain unclear. In this study, we investigated the expression and roles of ZNF545 in multiple myeloma (MM). ZNF545 was frequently downregulated in MM tissues compared with non-tumor bone marrow tissues. ZNF545 expression was silenced by promoter methylation in MM cell lines, and could be restored by demethylation treatment. ZNF545 methylation was detected in 28.3% of MM tissues, compared with 4.3% of normal bone marrow tissues. ZNF545 transcriptionally activated the p53 signaling pathway but had no effect on Akt in MM, whereas ectopic expression of ZNF545 in silenced cells suppressed their proliferation and induced apoptosis. We therefore identified ZNF545 as a novel tumor suppressor inhibiting tumor growth through activation of the p53 pathway in MM. Moreover, tumor-specific methylation of ZNF545 may represent an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. -- Highlights: •Downregulated ZNF545 in MM tissues and cell lines and ectopic expression of ZNF545 suppresses tumor growth. •Tumor-specific methylation of ZNF545 represents an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. •ZNF545 exerts its tumor suppressive effects via transcriptional activating p53 pathway.

  10. Mutational myriad of tumor suppressor p53 in Filipino breast cancer: results and perspectives in molecular pathology and epidemiology

    International Nuclear Information System (INIS)

    Deocaris, Custer C.

    2000-04-01

    The p53 tumor suppressor is by far the most widely mutated gene in human cancers. p53 encodes a 53-kDa phosphoprotein, transcription-activator whose targets include genes and gene products that orchestrate genomic stability, cellular response to DNA damage, cell cycle progression apoptosis and aging (senescence). Analysis of the p53 gene profile has previously resulted in identifying several cancer-causative factors in the human setting, as well as, in creating a unique molecular profile of a tumor useful in the design of tailored-therapies for individual cancer patients. Our results in screening for p53 abnormalities in 140 Filipino patients with primary breast lesions confined from 1997-1998 in 5 major hospitals in Manila reveal that p53 plays an important role in the development and progression of breast cancer in at least 48% of all cases. Two methods of p53 analysis are employed, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction-temporal temperature gradient electrophoresis (PCR-TTGE). Inter-comparisons of method exhibit 63.3% concordance in 21 fresh breast carcinoma samples, with ELISA demonstrating 14% false-positives and 10% false-negatives. Only mutations in exon 7 (p=0.063) in the tumor samples how significant correlation with abnormal cellular elevation of p53. PCR-TTGE screening in a large series of 140 patients show that most genetic lesions are localized in exons 5 (41% of the total cases) and 6 (27% of the total cases). No mutations are, however, detected in the transactivation (exons 2-4) and oligomerization (exons 10-11) domains. Invasive carcinomas (stages II and III) are characterized with more frequent and diverse genetic alterations compared with benign tumors, most significantly at exon 5B (p=0.066) and at independently multiple sites (p=0.066). Earlier-onset cases (age of diagnosis < 50 yrs), known to be more clinico-pathologically aggressive, are diagnosed harboring more frequent p53 mutations centered at exon 7 (p=0

  11. Mutational myriad of tumor suppressor p53 in Filipino breast cancer: results and perspectives in molecular pathology and epidemiology

    Energy Technology Data Exchange (ETDEWEB)

    Deocaris, Custer C

    2000-04-01

    The p53 tumor suppressor is by far the most widely mutated gene in human cancers. p53 encodes a 53-kDa phosphoprotein, transcription-activator whose targets include genes and gene products that orchestrate genomic stability, cellular response to DNA damage, cell cycle progression apoptosis and aging (senescence). Analysis of the p53 gene profile has previously resulted in identifying several cancer-causative factors in the human setting, as well as, in creating a unique molecular profile of a tumor useful in the design of tailored-therapies for individual cancer patients. Our results in screening for p53 abnormalities in 140 Filipino patients with primary breast lesions confined from 1997-1998 in 5 major hospitals in Manila reveal that p53 plays an important role in the development and progression of breast cancer in at least 48% of all cases. Two methods of p53 analysis are employed, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction-temporal temperature gradient electrophoresis (PCR-TTGE). Inter-comparisons of method exhibit 63.3% concordance in 21 fresh breast carcinoma samples, with ELISA demonstrating 14% false-positives and 10% false-negatives. Only mutations in exon 7 (p=0.063) in the tumor samples how significant correlation with abnormal cellular elevation of p53. PCR-TTGE screening in a large series of 140 patients show that most genetic lesions are localized in exons 5 (41% of the total cases) and 6 (27% of the total cases). No mutations are, however, detected in the transactivation (exons 2-4) and oligomerization (exons 10-11) domains. Invasive carcinomas (stages II and III) are characterized with more frequent and diverse genetic alterations compared with benign tumors, most significantly at exon 5B (p=0.066) and at independently multiple sites (p=0.066). Earlier-onset cases (age of diagnosis < 50 yrs), known to be more clinico-pathologically aggressive, are diagnosed harboring more frequent p53 mutations centered at exon 7 (p=0

  12. Role of Tumor Suppressor P53 in Megakaryopoiesis and Platelet Function

    Science.gov (United States)

    Apostolidis, Pani A.; Woulfe, Donna S.; Chavez, Massiel; Miller, William M.; Papoutsakis, Eleftherios T.

    2011-01-01

    The pathobiological role of p53 has been widely studied, however its role in normophysiology is relatively unexplored. We previously showed that p53 knock-down increased ploidy in megakaryocytic cultures. This study aims to examine the effect of p53 loss on in vivo megakaryopoiesis, platelet production and function, and to investigate the basis for greater ploidy in p53−/− megakaryocytic cultures. Here, we used flow cytometry to analyze ploidy, DNA synthesis and apoptosis in murine cultured and bone marrow megakaryocytes following thrombopoietin administration and to analyze fibrinogen binding to platelets in vitro. Culture of p53−/− marrow cells for 6 days with thrombopoietin gave rise to 1.7-fold more megakaryocytes, 26.1±3.6% of which reached ploidy classes ≥64N compared to 8.2±0.9% of p53+/+ megakaryocytes. This was due to 30% greater DNA synthesis in p53−/− megakaryocytes and 31% greater apoptosis in p53+/+ megakaryocytes by day 4 of culture. Although the bone marrow and spleen steady-state megakaryocytic content and ploidy were similar in p53+/+ and p53−/− mice, thrombopoietin administration resulted in increased megakaryocytic polyploidization in p53−/− mice. Although their platelet counts were normal, p53−/− mice exhibited significantly longer bleeding times and p53−/− platelets were less sensitive than p53+/+ platelets to agonist-induced fibrinogen binding and P-selectin secretion. In summary, our in vivo and ex-vivo studies indicate that p53 loss leads to increased polyploidization during megakaryopoiesis. Our findings also suggest for the first time a direct link between p53 loss and the development of fully functional platelets resulting in hemostatic deficiencies. PMID:22024107

  13. The tumor suppressors pRB and p53 as regulators of adipocyte differentiation and function

    DEFF Research Database (Denmark)

    Hallenborg, Philip; Feddersen, Søren; Madsen, Lise

    2009-01-01

    BACKGROUND: The retinoblastoma protein (pRB) and p53 are crucial members of regulatory networks controlling the cell cycle and apoptosis, and a hallmark of virtually all cancers is dysregulation of expression or function of pRB or p53. Although they are best known for their role in cancer...

  14. Senescence-Associated Secretory Phenotypes Reveal Cell-Nonautonomous Functions of Oncogenic RAS and the p53 Tumor Suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Copp& #233; , Jean-Philippe; Patil, Christopher; Rodier, Francis; Sun, Yu; Munoz, Denise; Goldstein, Joshua; Nelson, Peter; Desprez, Pierre-Yves; Campisi, Judith

    2008-10-24

    Cellular senescence suppresses cancer by arresting cell proliferation, essentially permanently, in response to oncogenic stimuli, including genotoxic stress. We modified the use of antibody arrays to provide a quantitative assessment of factors secreted by senescent cells. We show that human cells induced to senesce by genotoxic stress secrete myriad factors associated with inflammation and malignancy. This senescence-associated secretory phenotype (SASP) developed slowly over several days and only after DNA damage of sufficient magnitude to induce senescence. Remarkably similar SASPs developed in normal fibroblasts, normal epithelial cells, and epithelial tumor cells after genotoxic stress in culture, and in epithelial tumor cells in vivo after treatment of prostate cancer patients with DNA-damaging chemotherapy. In cultured premalignant epithelial cells, SASPs induced an epithelial-mesenchyme transition and invasiveness, hallmarks of malignancy, by a paracrine mechanism that depended largely on the SASP factors interleukin (IL)-6 and IL-8. Strikingly, two manipulations markedly amplified, and accelerated development of, the SASPs: oncogenic RAS expression, which causes genotoxic stress and senescence in normal cells, and functional loss of the p53 tumor suppressor protein. Both loss of p53 and gain of oncogenic RAS also exacerbated the promalignant paracrine activities of the SASPs. Our findings define a central feature of genotoxic stress-induced senescence. Moreover, they suggest a cell-nonautonomous mechanism by which p53 can restrain, and oncogenic RAS can promote, the development of age-related cancer by altering the tissue microenvironment.

  15. PHTS, a novel putative tumor suppressor, is involved in the transformation reversion of HeLaHF cells independently of the p53 pathway

    International Nuclear Information System (INIS)

    Yu Dehua; Fan, Wufang; Liu, Guohong; Nguy, Vivian; Chatterton, Jon E.; Long Shilong; Ke, Ning; Meyhack, Bernd; Bruengger, Adrian; Brachat, Arndt; Wong-Staal, Flossie; Li, Qi-Xiang

    2006-01-01

    HeLaHF is a non-transformed revertant of HeLa cells, likely resulting from the activation of a putative tumor suppressor(s). p53 protein was stabilized in this revertant and reactivated for certain transactivation functions. Although p53 stabilization has not conclusively been linked to the reversion, it is clear that the genes in p53 pathway are involved. The present study confirms the direct role of p53 in HeLaHF reversion by demonstrating that RNAi-mediated p53 silencing partially restores anchorage-independent growth potential of the revertant through the suppression of anoikis. In addition, we identified a novel gene, named PHTS, with putative tumor suppressor properties, and showed that this gene is also involved in HeLaHF reversion independently of the p53 pathway. Expression profiling revealed that PHTS is one of the genes that is up-regulated in HeLaHF but not in HeLa. It encodes a putative protein with CD59-like domains. RNAi-mediated PHTS silencing resulted in the partial restoration of transformation (anchorage-independent growth) in HeLaHF cells, similar to that of p53 gene silencing, implying its tumor suppressor effect. However, the observed increased transformation potential by PHTS silencing appears to be due to an increased anchorage-independent proliferation rate rather than suppression of anoikis, unlike the effect of p53 silencing. p53 silencing did not affect PHTS gene expression, and vice versa, suggesting PHTS may function in a new and p53-independent tumor suppressor pathway. Furthermore, over-expression of PHTS in different cancer cell lines, in addition to HeLa, reduces cell growth likely via induced apoptosis, confirming the broad PHTS tumor suppressor properties

  16. Cancer Chemoprevention by Resveratrol: The p53 Tumor Suppressor Protein as a Promising Molecular Target

    Directory of Open Access Journals (Sweden)

    Danielly C. Ferraz da Costa

    2017-06-01

    Full Text Available Increasing epidemiological and experimental evidence has demonstrated an inverse relationship between the consumption of plant foods and the incidence of chronic diseases, including cancer. Microcomponents that are naturally present in such foods, especially polyphenols, are responsible for the benefits to human health. Resveratrol is a diet-derived cancer chemopreventive agent with high therapeutic potential, as demonstrated by different authors. The aim of this review is to collect and present recent evidence from the literature regarding resveratrol and its effects on cancer prevention, molecular signaling (especially regarding the involvement of p53 protein, and therapeutic perspectives with an emphasis on clinical trial results to date.

  17. P53 tumor suppressor gene and protein expression is altered in cell lines derived from spontaneous and alpha-radiation-induced canine lung tumors

    International Nuclear Information System (INIS)

    Tierney, L.A.; Johnson, N.F.; Lechner, J.F.

    1994-01-01

    Mutations in the p53 tumor suppressor gene are the most frequently occurring gene alterations in malignant human cancers, including lung cancer. In lung cancer, common point mutations within conserved exons of the p53 gene result in a stabilized form of mutant protein which is detectable in most cases by immunohistochemistry. In addition to point mutations, allelic loss, rearrangements, and deletions of the p53 gene have also been detected in both human and rodent tumors. It has been suggested that for at least some epithelial neoplasms, the loss of expression of wild-type p53 protein may be more important for malignant transformation than the acquisition of activating mutations. Mechanisms responsible for the loss of expression of wild-type protein include gene deletion or rearrangement, nonsense or stop mutations, mutations within introns or upstream regulatory regions of the gene, and accelerated rates of degradation of the protein by DNA viral oncoproteins

  18. The tumor suppressor SHIP1 colocalizes in nucleolar cavities with p53 and components of PML nuclear bodies.

    Science.gov (United States)

    Ehm, Patrick; Nalaskowski, Marcus M; Wundenberg, Torsten; Jücker, Manfred

    2015-01-01

    The inositol 5-phosphatase SHIP1 is a negative regulator of signaling processes in haematopoietic cells. By converting PI(3,4,5)P3 to PtdIns(3,4)P2 at the plasma membrane, SHIP1 modifies PI3-kinase mediated signaling. We have recently demonstrated that SHIP1 is a nucleo-cytoplasmic shuttling protein and SHIP1 nuclear puncta partially colocalize with FLASH, a component of nuclear bodies. In this study, we demonstrate that endogenous SHIP1 localizes to intranucleolar regions of both normal and leukemic haematopoietic cells. In addition, we report that ectopically expressed SHIP1 accumulates in nucleolar cavities and colocalizes with the tumor suppressor protein p53 and components of PML nuclear bodies (e.g. SP100, SUMO-1 and CK2). Moreover, SHIP1 also colocalizes in nucleolar cavities with components of the ubiquitin-proteasome pathway. By using confocal microscopy data, we generated 3D-models revealing the enormous extent of the SHIP1 aggresomes in the nucleolus. Furthermore, treatment of cells with the proteasome inhibitor MG132 causes an enlargement of nucleolar SHIP1 containing structures. Unexpectedly, this accumulation can be partially prevented by treatment with the inhibitor of nuclear protein export Leptomycin B. In recent years, several proteins aggregating in nucleolar cavities were shown to be key factors of neurodegenerative diseases and cancerogenesis. Our findings support current relevance of nuclear localized SHIP1.

  19. LACTB, a novel epigenetic silenced tumor suppressor, inhibits colorectal cancer progression by attenuating MDM2-mediated p53 ubiquitination and degradation.

    Science.gov (United States)

    Zeng, Kaixuan; Chen, Xiaoxiang; Hu, Xiuxiu; Liu, Xiangxiang; Xu, Tao; Sun, Huiling; Pan, Yuqin; He, Bangshun; Wang, Shukui

    2018-06-13

    Colorectal cancer (CRC) is one of the most common aggressive malignancies. Like other solid tumors, inactivation of tumor suppressor genes and activation of oncogenes occur during CRC development and progression. Recently, a novel tumor suppressor, LACTB, was proposed to inhibit tumor progression, but the functional and clinical significance of this tumor suppressor in CRC remains unexplored. Herein, we found LACTB was significantly downregulated in CRC due to promoter methylation and histone deacetylation, which was associated with metastasis and advanced clinical stage. CRC patients with low LACTB expression had poorer overall survival and LACTB also determined to be an independent prognostic factor for poorer outcome. Ectopic expression of LACTB suppressed CRC cells proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro and inhibited CRC growth and metastasis in vivo, while knockout of LACTB by CRISPR/Cas9 gene editing technique resulted in an opposite phenotype. Interestingly, LACTB could exert antitumorigenic effect only in HCT116 and HCT8 cells harboring wild-type TP53, but not in HT29 and SW480 cells harboring mutant TP53 or HCT116 p53 -/- cells. Mechanistic studies demonstrated that LACTB could directly bind to the C terminus of p53 to inhibit p53 degradation by preventing MDM2 from interacting with p53. Moreover, ablation of p53 attenuated the antitumorigenic effects of LACTB overexpression in CRC. Collectively, our findings successfully demonstrate for the first time that LACTB is a novel epigenetic silenced tumor suppressor through modulating the stability of p53, supporting the pursuit of LACTB as a potential therapeutic target for CRC.

  20. Malignant Trigeminal Nerve Sheath Tumor and Anaplastic Astrocytoma Collision Tumor with High Proliferative Activity and Tumor Suppressor P53 Expression

    Directory of Open Access Journals (Sweden)

    Maher Kurdi

    2014-01-01

    Full Text Available Background. The synchronous development of two primary brain tumors of distinct cell of origin in close proximity or in contact with each other is extremely rare. We present the first case of collision tumor with two histological distinct tumors. Case Presentation. A 54-year-old woman presented with progressive atypical left facial pain and numbness for 8 months. MRI of the brain showed left middle cranial fossa heterogeneous mass extending into the infratemporal fossa. At surgery, a distinct but intermingled intra- and extradural tumor was demonstrated which was completely removed through left orbitozygomatic-temporal craniotomy. Histopathological examination showed that the tumor had two distinct components: malignant nerve sheath tumor of the trigeminal nerve and temporal lobe anaplastic astrocytoma. Proliferative activity and expressed tumor protein 53 (TP53 gene mutations were demonstrated in both tumors. Conclusions. We describe the first case of malignant trigeminal nerve sheath tumor (MTNST and anaplastic astrocytoma in collision and discuss the possible hypothesis of this rare occurrence. We propose that MTNST, with TP53 mutation, have participated in the formation of anaplastic astrocytoma, or vice versa.

  1. Irradiation-injured brain tissues can self-renew in the absence of the pivotal tumor suppressor p53 in the medaka (Oryzias latipes) embryo

    International Nuclear Information System (INIS)

    Yasuda, Takako; Nagata, Kento; Igarashi, Kento; Watanabe-Asaka, Tomomi; Oda, Shoji; Mitani, Hiroshi; Kimori, Yoshitaka

    2016-01-01

    The tumor suppressor protein, p53, plays pivotal roles in regulating apoptosis and proliferation in the embryonic and adult central nervous system (CNS) following neuronal injuries such as those induced by ionizing radiation. There is increasing evidence that p53 negatively regulates the self-renewal of neural stem cells in the adult murine brain; however, it is still unknown whether p53 is essential for self-renewal in the injured developing CNS. Previously, we demonstrated that the numbers of apoptotic cells in medaka (Oryzias latipes) embryos decreased in the absence of p53 at 12-24 h after irradiation with 10-Gy gamma rays. Here, we used histology to examine the later morphological development of the irradiated medaka brain. In p53-deficient larvae, the embryonic brain possessed similar vacuoles in the brain and retina, although the vacuoles were much smaller and fewer than those found in wild-type embryos. At the time of hatching (6 days after irradiation), no brain abnormality was observed. In contrast, severe disorganized neuronal arrangements were still present in the brain of irradiated wild-type embryos. Our present results demonstrated that self-renewal of the brain tissue completed faster in the absence of p53 than wild type at the time of hatching because p53 reduces the acute severe neural apoptosis induced by irradiation, suggesting that p53 is not essential for tissue self-renewal in developing brain. (author)

  2. Identification and characterization of small molecule inhibitors of the calcium-dependent S100B-p53 tumor suppressor interaction.

    Science.gov (United States)

    Markowitz, Joseph; Chen, Ijen; Gitti, Rossi; Baldisseri, Donna M; Pan, Yongping; Udan, Ryan; Carrier, France; MacKerell, Alexander D; Weber, David J

    2004-10-07

    The binding of S100B to p53 down-regulates wild-type p53 tumor suppressor activity in cancer cells such as malignant melanoma, so a search for small molecules that bind S100B and prevent S100B-p53 complex formation was undertaken. Chemical databases were computationally searched for potential inhibitors of S100B, and 60 compounds were selected for testing on the basis of energy scoring, commercial availability, and chemical similarity clustering. Seven of these compounds bound to S100B as determined by steady state fluorescence spectroscopy (1.0 microM model of one such inhibitor, pentamidine, bound to Ca(2+)-loaded S100B was calculated using intermolecular NOE data between S100B and the drug, and indicates that pentamidine binds into the p53 binding site on S100B defined by helices 3 and 4 and loop 2 (termed the hinge region).

  3. Alterations of tumor suppressor genes (Rb, p16, p27 and p53) and an increased FDG uptake in lung cancer

    International Nuclear Information System (INIS)

    Sasaki, Masayuki; Sugio, Kenji; Kuwabara, Yasuo

    2003-01-01

    The FDG uptake in lung cancer is considered to reflect the degree of malignancy, while alterations of some tumor suppressor genes are considered to be related to the malignant biological behavior of tumors. The aim of this study is to examine the relationship between FDG-PET and alterations in the tumor suppression genes of lung cancer. We examined 28 patients with primary lung cancer who underwent FDG-PET before surgery consisting of 17 patients with adenocarcinoma, 10 with squamous cell carcinoma and 1 with large cell carcinoma. The FDG-PET findings were evaluated based on the standardized uptake value (SUV). Alterations in the tumor suppressor genes, Rb, p16, p27 and p53, were evaluated immunohistochemically. The FDG uptake in lung cancer with alteration in each tumor suppressor gene tended to be higher than in those genes without alterations, although the differences were not significant. In 15 tumors with alterations in either tumor suppressor genes, the FDG uptake was 6.83±3.21. On the other hand, the mean FDG uptake was 1.95 in 2 tumors without alterations in any genes. The difference in the FDG uptake between the 2 groups was statistically significant (p<0.001). In conclusion, the presence of abnormalities in the tumor suppressor genes, which results in an accelerated cell proliferation, is thus considered to increase the FDG uptake in lung cancer. (author)

  4. The homeoprotein DLX3 and tumor suppressor p53 co-regulate cell cycle progression and squamous tumor growth.

    Science.gov (United States)

    Palazzo, E; Kellett, M; Cataisson, C; Gormley, A; Bible, P W; Pietroni, V; Radoja, N; Hwang, J; Blumenberg, M; Yuspa, S H; Morasso, M I

    2016-06-16

    Epidermal homeostasis depends on the coordinated control of keratinocyte cell cycle. Differentiation and the alteration of this balance can result in neoplastic development. Here we report on a novel DLX3-dependent network that constrains epidermal hyperplasia and squamous tumorigenesis. By integrating genetic and transcriptomic approaches, we demonstrate that DLX3 operates through a p53-regulated network. DLX3 and p53 physically interact on the p21 promoter to enhance p21 expression. Elevating DLX3 in keratinocytes produces a G1-S blockade associated with p53 signature transcriptional profiles. In contrast, DLX3 loss promotes a mitogenic phenotype associated with constitutive activation of ERK. DLX3 expression is lost in human skin cancers and is extinguished during progression of experimentally induced mouse squamous cell carcinoma (SCC). Reinstatement of DLX3 function is sufficient to attenuate the migration of SCC cells, leading to decreased wound closure. Our data establish the DLX3-p53 interplay as a major regulatory axis in epidermal differentiation and suggest that DLX3 is a modulator of skin carcinogenesis.

  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. Amplification of Mdmx (or Mdm4) directly contributes to tumor formation by inhibiting p53 tumor suppressor activity

    DEFF Research Database (Denmark)

    Danovi, Davide; Meulmeester, Erik; Pasini, Diego

    2004-01-01

    has been established. However, a direct contribution of Mdmx to tumor formation remains to be demonstrated. Here we show that retrovirus-mediated Mdmx overexpression allows primary mouse embryonic fibroblast immortalization and leads to neoplastic transformation in combination with HRas(V12...

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

    International Nuclear Information System (INIS)

    Tommaso, Anne di; Hagen, Jussara; Tompkins, Van; Muniz, Viviane; Dudakovic, Amel; Kitzis, Alain; Ladeveze, Veronique; Quelle, Dawn E.

    2009-01-01

    The Alternative Reading Frame (ARF) protein suppresses tumorigenesis through p53-dependent and p53-independent pathways. Most of ARF's anti-proliferative activity is conferred by sequences in its first exon. Previous work showed specific amino acid changes occurred in that region during primate evolution, so we programmed those changes into human p14ARF to assay their functional impact. Two human p14ARF residues (Ala 14 and Thr 31 ) were found to destabilize the protein while two others (Val 24 and Ala 41 ) promoted more efficient p53 stabilization and activation. Despite those effects, all modified p14ARF forms displayed robust p53-dependent anti-proliferative activity demonstrating there are no significant biological differences in p53-mediated growth suppression associated with simian versus human p14ARF residues. In contrast, p53-independent p14ARF function was considerably altered by several residue changes. Val 24 was required for p53-independent growth suppression whereas multiple residues (Val 24 , Thr 31 , Ala 41 and His 60 ) enabled p14ARF to block or reverse the inherent chromosomal instability of p53-null MEFs. Together, these data pinpoint specific residues outside of established p14ARF functional domains that influence its expression and signaling activities. Most intriguingly, this work reveals a novel and direct role for p14ARF in the p53-independent maintenance of genomic stability.

  8. Inability of p53-reactivating compounds Nutlin-3 and RITA to overcome p53 resistance in tumor cells deficient in p53Ser46 phosphorylation.

    Science.gov (United States)

    Ma, Teng; Yamada, Shumpei; Ichwan, Solachuddin J A; Iseki, Sachiko; Ohtani, Kiyoshi; Otsu, Megumi; Ikeda, Masa-Aki

    2012-01-20

    The p53 tumor suppressor protein plays key roles in protecting cells from tumorigenesis. Phosphorylation of p53 at Ser46 (p53Ser46) is considered to be a crucial modification regulating p53-mediated apoptosis. Because the activity of p53 is impaired in most human cancers, restoration of wild-type p53 (wt-p53) function by its gene transfer or by p53-reactivating small molecules has been extensively investigated. The p53-reactivating compounds Nutlin-3 and RITA activate p53 in the absence of genotoxic stress by antagonizing the action of its negative regulator Mdm2. Although controversial, Nutlin-3 was shown to induce p53-mediated apoptosis in a manner independent of p53 phosphorylation. Recently, RITA was shown to induce apoptosis by promoting p53Ser46 phosphorylation. Here we examined whether Nutlin-3 or RITA can overcome resistance to p53-mediated apoptosis in p53-resistant tumor cell lines lacking the ability to phosphorylate p53Ser46. We show that Nutlin-3 did not rescue the apoptotic defect of a Ser46 phosphorylation-defective p53 mutant in p53-sensitive tumor cells, and that RITA neither restored p53Ser46 phosphorylation nor induced apoptosis in p53Ser46 phosphorylation-deficient cells retaining wt-p53. Furthermore, treatment with Nutlin-3 or RITA together with adenoviral p53 gene transfer also failed to induce apoptosis in p53Ser46 phosphorylation-deficient cells either expressing or lacking wt-p53. These results indicate that neither Nutlin-3 nor RITA in able to induce p53-mediated apoptosis in the absence of p53Ser46 phosphorylation. Thus, the dysregulation of this phosphorylation in tumor cells may be a critical factor that limits the efficacy of these p53-based cancer therapies. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Flavopiridol induces apoptosis in glioma cell lines independent of retinoblastoma and p53 tumor suppressor pathway alterations by a caspase-independent pathway.

    Science.gov (United States)

    Alonso, Michelle; Tamasdan, Cristina; Miller, Douglas C; Newcomb, Elizabeth W

    2003-02-01

    Flavopiridol is a synthetic flavone, which inhibits growth in vitro and in vivo of several solid malignancies such as renal, prostate, and colon cancers. It is a potent cyclin-dependent kinase inhibitor presently in clinical trials. In this study, we examined the effect of flavopiridol on a panel of glioma cell lines having different genetic profiles: five of six have codeletion of p16(INK4a) and p14(ARF); three of six have p53 mutations; and one of six shows overexpression of mouse double minute-2 (MDM2) protein. Independent of retinoblastoma and p53 tumor suppressor pathway alterations, flavopiridol induced apoptosis in all cell lines but through a caspase-independent mechanism. No cleavage products for caspase 3 or its substrate poly(ADP-ribose) polymerase or caspase 8 were detected. The pan-caspase inhibitor Z-VAD-fmk did not inhibit flavopiridol-induced apoptosis. Mitochondrial damage measured by cytochrome c release and transmission electron microscopy was not observed in drug-treated glioma cells. In contrast, flavopiridol treatment induced translocation of apoptosis-inducing factor from the mitochondria to the nucleus. The proteins cyclin D(1) and MDM2 involved in the regulation of retinoblastoma and p53 activity, respectively, were down-regulated early after flavopiridol treatment. Given that MDM2 protein can confer oncogenic properties under certain circumstances, loss of MDM2 expression in tumor cells could promote increased chemosensitivity. After drug treatment, a low Bcl-2/Bax ratio was observed, a condition that may favor apoptosis. Taken together, the data indicate that flavopiridol has activity against glioma cell lines in vitro and should be considered for clinical development in the treatment of glioblastoma multiforme.

  10. p53-Dependent Nestin Regulation Links Tumor Suppression to Cellular Plasticity in Liver Cancer

    DEFF Research Database (Denmark)

    Tschaharganeh, Darjus F; Xue, Wen; Calvisi, Diego F

    2014-01-01

    The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the expansion of malignant cells, and as a consequence, p53 is lost or mutated in the majority of human cancers. Here, we show that p53 restricts expression of the stem and progenitor-cell-associated protei...... by p53 restricts cellular plasticity and tumorigenesis in liver cancer....

  11. Alterations in tumour suppressor gene p53 in human gliomas from ...

    Indian Academy of Sciences (India)

    Unknown

    Alterations in the tumour suppressor p53 gene are among the most common defects seen in a variety of human cancers. ..... rangement of the EGF receptor gene in primary human brain tumors ... the INK4A gene in superficial bladder tumors.

  12. p53-Mediated Molecular Control of Autophagy in Tumor Cells

    Directory of Open Access Journals (Sweden)

    Maria Mrakovcic

    2018-03-01

    Full Text Available Autophagy is an indispensable mechanism of the eukaryotic cell, facilitating the removal and renewal of cellular components and thereby balancing the cell’s energy consumption and homeostasis. Deregulation of autophagy is now regarded as one of the characteristic key features contributing to the development of tumors. In recent years, the suppression of autophagy in combination with chemotherapeutic treatment has been approached as a novel therapy in cancer treatment. However, depending on the type of cancer and context, interference with the autophagic machinery can either promote or disrupt tumorigenesis. Therefore, disclosure of the major signaling pathways that regulate autophagy and control tumorigenesis is crucial. To date, several tumor suppressor proteins and oncogenes have emerged as eminent regulators of autophagy whose depletion or mutation favor tumor formation. The mammalian cell “janitor” p53 belongs to one of these tumor suppressors that are most commonly mutated in human tumors. Experimental evidence over the last decade convincingly reports that p53 can act as either an activator or an inhibitor of autophagy depending on its subcellular localization and its mode of action. This finding gains particular significance as p53 deficiency or mutant variants of p53 that accumulate in the cytoplasm of tumor cells enable activation of autophagy. Accordingly, we recently identified p53 as a molecular hub that regulates autophagy and apoptosis in histone deacetylase inhibitor-treated uterine sarcoma cells. In light of this novel experimental evidence, in this review, we focus on p53 signaling as a mediator of the autophagic pathway in tumor cells.

  13. p63 expression confers significantly better survival outcomes in high-risk diffuse large B-cell lymphoma and demonstrates p53-like and p53-independent tumor suppressor function

    DEFF Research Database (Denmark)

    Xu-Monette, Zijun Y; Zhang, Shanxiang; Li, Xin

    2016-01-01

    with a pan-p63-monoclonal antibody and correlated it with other clinicopathologic factors and clinical outcomes. p63 expression was observed in 42.5% of DLBCL, did not correlate with p53 levels, but correlated with p21, MDM2, p16INK4A, Ki-67, Bcl-6, IRF4/MUM-1 and CD30 expression, REL gains, and BCL6...... was likely due to the association of p63 expression with high-risk IPI, and potential presence of ∆Np63 isoform in TP63 rearranged patients (a mere speculation). Gene expression profiling suggested that p63 has both overlapping and distinct functions compared with p53, and that p63 and mutated p53 antagonize...

  14. Gelsolin negatively regulates the activity of tumor suppressor p53 through their physical interaction in hepatocarcinoma HepG2 cells

    International Nuclear Information System (INIS)

    An, Joo-Hee; Kim, Jung-Woong; Jang, Sang-Min; Kim, Chul-Hong; Kang, Eun-Jin; Choi, Kyung-Hee

    2011-01-01

    Highlights: → The actin binding protein Gelsolin (GSN) interacts with transcription factor p53. → GSN interacts with transactivation- and DNA binding domains of p53. → GSN represses transactivity of p53 via inhibition of nuclear translocation of p53. → GSN inhibits the p53-mediated apoptosis in hepatocarcinoma HepG2 cells. -- Abstract: As a transcription factor, p53 modulates several cellular responses including cell-cycle control, apoptosis, and differentiation. In this study, we have shown that an actin regulatory protein, gelsolin (GSN), can physically interact with p53. The nuclear localization of p53 is inhibited by GSN overexpression in hepatocarcinoma HepG2 cells. Additionally, we demonstrate that GSN negatively regulates p53-dependent transcriptional activity of a reporter construct, driven by the p21-promoter. Furthermore, p53-mediated apoptosis was repressed in GSN-transfected HepG2 cells. Taken together, these results suggest that GSN binds to p53 and this interaction leads to the inhibition of p53-induced apoptosis by anchoring of p53 in the cytoplasm in HepG2 cells.

  15. p53 regulates cytoskeleton remodeling to suppress tumor progression.

    Science.gov (United States)

    Araki, Keigo; Ebata, Takahiro; Guo, Alvin Kunyao; Tobiume, Kei; Wolf, Steven John; Kawauchi, Keiko

    2015-11-01

    Cancer cells possess unique characteristics such as invasiveness, the ability to undergo epithelial-mesenchymal transition, and an inherent stemness. Cell morphology is altered during these processes and this is highly dependent on actin cytoskeleton remodeling. Regulation of the actin cytoskeleton is, therefore, important for determination of cell fate. Mutations within the TP53 (tumor suppressor p53) gene leading to loss or gain of function (GOF) of the protein are often observed in aggressive cancer cells. Here, we highlight the roles of p53 and its GOF mutants in cancer cell invasion from the perspective of the actin cytoskeleton; in particular its reorganization and regulation by cell adhesion molecules such as integrins and cadherins. We emphasize the multiple functions of p53 in the regulation of actin cytoskeleton remodeling in response to the extracellular microenvironment, and oncogene activation. Such an approach provides a new perspective in the consideration of novel targets for anti-cancer therapy.

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

    International Nuclear Information System (INIS)

    Haensgen, Gabriele; Krause, Ulf; Becker, Axel; Stadler, Peter; Lautenschlaeger, Christine; Wohlrab, Wolfgang; Rath, Friedrich W.; Molls, Michael; Dunst, Juergen

    2001-01-01

    Background: The p53 protein is involved in the regulation of initiation of apoptosis. In vitro, p53-deficient cells do not respond to hypoxia with apoptosis as do p53-normal cells, and this may lead to a relative growth advantage of cells without a functioning p53 under hypoxia. On the basis of this hypothesis, a selection of cells with a functionally inactive p53 may occur in hypoxic tumors. The development of uterine cervical carcinomas is closely associated with infections of human papilloma viruses, which may cause a degradation of the tumor suppressor gene p53, resulting in a restriction of apoptosis. Thus, cervical cancers have often a functionally inactive p53. The purpose of our clinical study was therefore to investigate the association between p53, hypoxia, and prognosis in cervical cancers in which the oxygenation status can be determined by clinical methods. Material and Methods: Seventy patients with locally advanced squamous cell cervical cancer Stages IIB (n=14), IIIB (n=49), and IVA (n=7) were investigated in the period from 1996 through 1999. All were treated with definitive radiotherapy with curative intent by a combination of external radiotherapy plus high-dose-rate afterloading. Before therapy, tumor oxygenation was measured with a needle probe polarographically using the Eppendorf histograph. Hypoxic tumors were defined as those with pO 2 measurements below 5 mm Hg (HF5). Pretreatment biopsies were taken and analyzed immunohistologically for p53 protein expression with the DO-7 antibody. The DNA index was measured by flow cytometry. The statistical data analysis was done with SPSS 9.0 for Windows. Results: The 3-year overall survival was 55% for the whole group of patients. Clinical prognostic factors in a multivariate analysis were pretreatment hemoglobin level (3-year survival 62% for patients with a pretreatment hemoglobin ≥11 g/dl vs. 27% for hemoglobin <11 g/dl, p=0.006) and FIGO stage (Stage IIB: 65%; Stage IIIB: 60%; Stage IVA: 29%, p

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

    NARCIS (Netherlands)

    Nantasanti, Sathidpak; Toussaint, Mathilda J. M.; Youssef, Sameh A.; Tooten, Peter C. J.; de Bruin, Alain

    2016-01-01

    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

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

    Science.gov (United States)

    Wachter, Franziska; Grunert, Michaela; Blaj, Cristina; Weinstock, David M; Jeremias, Irmela; Ehrhardt, Harald

    2013-04-17

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

  19. Proinflammatory cytokines and bile acids upregulate ΔNp73 protein, an inhibitor of p53 and p73 tumor suppressors.

    Directory of Open Access Journals (Sweden)

    Elena Zaika

    Full Text Available Gastroesophageal reflux disease (GERD is the main etiological factor behind the recent rapid increase in the incidence of esophageal adenocarcinoma. During reflux, esophageal cells are exposed to bile at low pH resulting in cellular damage and inflammation, which are known to facilitate cancer development. In this study, we investigated the regulation of p73 isoform, ΔNp73α, in the reflux condition. Previous studies have reported that ΔNp73 exhibits anti-apoptotic and oncogenic properties through inhibition of p53 and p73 proteins. We found that direct exposure of esophageal cells to bile acids in an acidic environment alters the phosphorylation of ΔNp73, its subcellular localization and increases ΔNp73 protein levels. Upregulation of ΔNp73 was also observed in esophageal tissues collected from patients with GERD and Barrett's metaplasia, a precancerous lesion in the esophagus associated with gastric reflux. c-Abl, p38 MAPK, and IKK protein kinases were identified to interact in the regulation of ΔNp73. Their inhibition with chemotherapeutic agents and siRNA suppresses ΔNp73. We also found that pro-inflammatory cytokines, IL-1β and TNFα, are potent inducers of ΔNp73α, which further enhance the bile acids/acid effect. Combined, our studies provide evidence that gastroesophageal reflux alters the regulation of oncogenic ΔNp73 isoform that may facilitate tumorigenic transformation of esophageal metaplastic epithelium.

  20. Tumor suppressors: enhancers or suppressors of regeneration?

    Science.gov (United States)

    Pomerantz, Jason H.; Blau, Helen M.

    2013-01-01

    Tumor suppressors are so named because cancers occur in their absence, but these genes also have important functions in development, metabolism and tissue homeostasis. Here, we discuss known and potential functions of tumor suppressor genes during tissue regeneration, focusing on the evolutionarily conserved tumor suppressors pRb1, p53, Pten and Hippo. We propose that their activity is essential for tissue regeneration. This is in contrast to suggestions that tumor suppression is a trade-off for regenerative capacity. We also hypothesize that certain aspects of tumor suppressor pathways inhibit regenerative processes in mammals, and that transient targeted modification of these pathways could be fruitfully exploited to enhance processes that are important to regenerative medicine. PMID:23715544

  1. Analysis of p53- immunoreactivity in astrocytic brain tumors

    Directory of Open Access Journals (Sweden)

    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.

  2. [Punish or cherish: p53, metabolism and tumor suppression].

    Science.gov (United States)

    Albagli, Olivier

    2015-10-01

    The p53 gene is essential for tumor suppression, but how it does so remains unclear. Upon genotoxic or oncogenic stresses, increased p53 activity induces transient cell cycle arrest, senescence or apoptosis, the three cornerstones of the so-called triumvirate. Accordingly, it has long been thought that p53 suppresses tumorigenesis by somehow counteracting cell proliferation or survival. However, several recently described genetically modified mice indicate that p53 can suppress tumorigenesis without triggering these three responses. Rather, as an important mechanism for tumor suppression, these mutant mice point to the ability of p53 to prevent the Warburg effect, that is to dampen glycolysis and foster mitochondrial respiration. Interestingly, these metabolic functions of p53 rely, in part, on its "unstressed" (basal) expression, a feature shared by its mechanistically linked anti-oxydant function. Together, these "conservative" activities of p53 may prevent tumor initiation by promoting and maintaining a normal oxidative metabolism and hence underly the "daily" tumor suppression by p53 in most cells. Conversely, destructive activities elicited by high p53 levels and leading to senescence or apoptosis provide a shield against partially or overtly transformed cells. This last situation, although relatively infrequent throughout life, is usual in experimental settings, which could explain the disproportionally high number of data implicating the triumvirate in tumor suppression by p53. © 2015 médecine/sciences – Inserm.

  3. The novel fusion proteins, GnRH-p53 and GnRHIII-p53, expression and their anti-tumor effect.

    Directory of Open Access Journals (Sweden)

    Peiyuan Jia

    Full Text Available p53, one of the most well studied tumor suppressor factor, is responsible to a variety of damage owing to the induction of apoptosis and cell cycle arrest in the tumor cells. More than 50% of human tumors contain mutation or deletion of p53. Gonadotrophin-releasing hormone (GnRH, as the ligand of Gonadotrophin-releasing hormone receptor (GnRH-R, was used to deliver p53 into tumor cells. The p53 fusion proteins GnRH-p53 and GnRH iii-p53 were expressed and their targeted anti-tumor effects were determined. GnRH mediates its fusion proteins transformation into cancer cells. The intracellular delivery of p53 fusion proteins exerted the inhibition of the growth of H1299 cells in vitro and the reduction of tumor volume in vivo. Their anti-tumor effect was functioned by the apoptosis and cell cycle arrest induced by p53. Hence, the fusion protein could be a novel protein drug for anti-tumor therapy.

  4. P53 function influences the effect of fractionated radiotherapy on glioblastoma tumors

    International Nuclear Information System (INIS)

    Haas-Kogan, Daphne A.; Kogan, Scott S.; Yount, Garret; Hsu, Jennie; Haas, Martin; Deen, Dennis F.; Israel, Mark A.

    1999-01-01

    Purpose: Glioblastoma multiforme brain tumors (GM) are treated with a spectrum of fractionation regimens based on the clinical and anatomical characteristics of the tumor but rarely based on the molecular characteristics of the individual neoplasm. This study tests the hypothesis that the response of cell lines derived from GM to fractionated radiotherapy depends on the function of wild-type p53 (wt p53), a tumor suppressor gene frequently mutated in GM tumors. Methods and Materials: Isogenic derivatives of glioblastoma cells differing only in p53 function were prepared using a retroviral vector expressing a dominant negative mutant of p53 (mt p53). Radiation survival in vitro was quantitated using linear quadratic and repair-saturation mathematical models. Apoptosis was assayed by a terminal deoxynucleotide transferase-labeling technique and chromatin morphology. Results: We have previously reported the generation of isogenic GM cell lines differing only in p53 function. U87-175.4, lacking wt p53 function, had a significantly lower α/β value than U87-LUX.8, expressing functional wt p53, leading us to hypothesize that fractionated irradiation would preferentially spare GM cells harboring mt p53 compared with those expressing functional, wt p53. Survival curves following either 2.0 Gy or 3.5 Gy/fraction demonstrated that lack of functional wt p53 was associated with resistance to fractionated irradiation. Radiation-induced apoptosis could not account for the observed differences in clonogenic survival. Rather, our data suggested that a deficit in the G1-checkpoint contributed to increased resistance to fractionated irradiation of cells expressing mutant p53. Conclusions: The effect of fractionated radiotherapy in GM may depend on the function of the tumor suppressor gene p53. A potential clinical consequence of these findings is that hyperfractionation regimens may provide a therapeutic advantage specifically for tumors expressing wt p53 whereas a radiotherapy

  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...... actually protects tumors from being killed by genotoxic agents. Furthermore, ATM-deficient cancer cells display strong nononcogene addiction to DNA-PKcs for survival after DNA damage, such that suppression of DNA-PKcs in vivo resensitizes inherently chemoresistant ATM-deficient tumors to genotoxic...

  6. Alterations in the K-ras and p53 genes in rat lung tumors

    Energy Technology Data Exchange (ETDEWEB)

    Belinsky, S.A.; Swafford, D.S.; Finch, G.L.; Mitchell, C.E. [Inhalation Toxicology Research Institute, Albuquerque, NM (United States)] [and others

    1997-06-01

    Activation of the K-ras protooncogene and inactivation of the p53 tumor suppressor gene are events common to many types of human cancers. Molecular epidemiology studies have associated mutational profiles in these genes with specific exposures. The purpose of this paper is to review investigations that have examined the role of the K-ras and p53 genes in lung tumors induced in the F344 rat by mutagenic and nonmutagenic exposures. Mutation profiles within the K-ras and p53 genes, if present in rat lung tumors, would help to define some of the molecular mechanisms underlying cancer induction by various environmental agents. Pulmonary adenocarcinomas or squamous cell carcinomas were induced by tetranitromethane (TNM), 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK), beryllium metal, plutonium-239, X-ray, diesel exhaust, or carbon black. These agents were chosen because the tumors they produced could arise via different types of DNA damage. Mutation of the K-ras gene was determined by approaches that included DNA transfection, direct sequencing, mismatch hybridization, and restriction fragment length polymorphism analysis. The frequency for mutation of the K-ras gene was exposure dependent. The transition mutations formed could have been derived from deamination of cytosine. Alteration in the p53 gene was assessed by immunohistochemical analysis for p53 protein and single-strand conformation polymorphism (SSCP) analysis of exons 4 to 9. None of the 93 adenocarinomas examined was immunoreactive toward the anti-p53 antibody CM1. In contrast, 14 of 71 squamous cell carcinomas exhibited nuclear p53 immunoreactivity with no correlation to type of exposure. However, SSCP analysis only detected mutations in 2 of 14 squamous cell tumors that were immunoreactive, suggesting that protein stabilization did not stem from mutations within the p53 gene. Thus, the p53 gene does not appear to be involved in the genesis of most rat lung tumors. 2 figs., 2 tabs., 48 refs.

  7. A combination of p53-activating APR-246 and phosphatidylserine-targeting antibody potently inhibits tumor development in hormone-dependent mutant p53-expressing breast cancer xenografts

    Directory of Open Access Journals (Sweden)

    Liang Y

    2018-03-01

    Full Text Available Yayun Liang,1 Benford Mafuvadze,1 Cynthia Besch-Williford,2 Salman M Hyder1 1Deparment of Biomedical Sciences and Dalton Cardiovascular Research Center, Columbia, MO, USA; 2IDEXX BioResearch, Columbia, MO, USA Background: Between 30 and 40% of human breast cancers express a defective tumor suppressor p53 gene. Wild-type p53 tumor suppressor protein promotes cell-cycle arrest and apoptosis and inhibits vascular endothelial growth factor–dependent angiogenesis, whereas mutant p53 protein (mtp53 lacks these functions, resulting in tumor cell survival and metastasis. Restoration of p53 function is therefore a promising drug-targeted strategy for combating mtp53-expressing breast cancer. Methods: In this study, we sought to determine whether administration of APR-246, a small-molecule drug that restores p53 function, in combination with 2aG4, an antibody that targets phosphatidylserine residues on tumor blood vessels and disrupts tumor vasculature, effectively inhibits advanced hormone-dependent breast cancer tumor growth. Results: APR-246 reduced cell viability in mtp53-expressing BT-474 and T47-D human breast cancer cells in vitro, and significantly induced apoptosis in a dose-dependent manner. However, APR-246 did not reduce cell viability in MCF-7 breast cancer cells, which express wild-type p53. We next examined APR-246’s anti-tumor effects in vivo using BT-474 and T47-D tumor xenografts established in female nude mice. Tumor-bearing mice were treated with APR-246 and/or 2aG4 and tumor volume followed over time. Tumor growth was more effectively suppressed by combination treatment than by either agent alone, and combination therapy completely eradicated some tumors. Immunohistochemistry analysis of tumor tissue sections demonstrated that combination therapy more effectively induced apoptosis and reduced cell proliferation in tumor xenografts than either agent alone. Importantly, combination therapy dramatically reduced the density of blood

  8. Circumvention and reactivation of the p53 oncogene checkpoint in mouse colon tumors.

    Science.gov (United States)

    Aizu, Wataru; Belinsky, Glenn S; Flynn, Christopher; Noonan, Emily J; Boes, Colleen C; Godman, Cassandra A; Doshi, Bindi; Nambiar, Prashant R; Rosenberg, Daniel W; Giardina, Charles

    2006-10-16

    The p53 tumor suppressor protein is sequence-normal in azoxymethane (AOM)-induced mouse colon tumors, making them a good model for human colon cancers that retain a wild type p53 gene. Cellular localization and co-immunoprecipitation experiments using a cell line derived from an AOM-induced colon tumor (AJ02-NM(0) cells) pointed to constitutively expressed Mdm2 as being an important negative regulator of p53 in these cells. Although the Mdm2 inhibitory protein p19/ARF was expressed in AJ02-NM(0) cells, its level of expression was not sufficient for p53 activation. We tested the response of AJ02-NM(0) cells to the recently developed Mdm2 inhibitor, Nutlin-3. Nutlin-3 was found to activate p53 DNA binding in AJ02-NM(0) cells, to a level comparable to doxorubicin and 5-fluorouracil (5-FU). In addition, Nutlin-3 increased expression of the p53 target genes Bax and PERP to a greater extent than doxorubicin or 5-FU, and triggered a G2/M phase arrest in these cells, compared to a G1 arrest triggered by doxorubicin and 5-FU. The differences in the cellular response may be related to differences in the kinetics of p53 activation and/or its post-translational modification status. In an ex vivo experiment, Nutlin-3 was found to activate p53 target gene expression and apoptosis in AOM-induced tumor tissue, but not in normal adjacent mucosa. Our data indicate that Mdm2 inhibitors may be an effective means of selectively targeting colon cancers that retain a sequence-normal p53 gene while sparing normal tissue and that the AOM model is an appropriate model for the preclinical development of these drugs.

  9. Recurrent pregnancy failure is associated with a polymorphism in the p53 tumour suppressor gene.

    Science.gov (United States)

    Pietrowski, Detlef; Bettendorf, Hertha; Riener, Eva-Katrin; Keck, Christoph; Hefler, Lukas A; Huber, Johannes C; Tempfer, Clemens

    2005-04-01

    The p53 tumour suppressor gene is a well-known factor regulating apoptosis in a wide variety of cells and tissues. Alterations in the p53 gene are among the most common genetic changes in human cancers. In addition, recent data provide evidence that p53 plays a critical role in mediating pregnancy by regulating steroid hormone activation. In idiopathic recurrent miscarriages (IRM), causes and associations are much debated as the exact pathophysiological mechanisms are unknown. In this study, we assess whether an established polymorphism in the p53 gene is associated with the occurrence of IRM. Genotyping was performed by PCR-based amplification of the p53 Arg and Pro variants at codon 72 in 175 cases of IRM and 143 controls. We observed a statistically significant association between carriage of the Pro allele and the occurrence of IRM (P = 0.03, odds ratio 1.49, confidence interval 1.04-2.14). Distribution of genotypes was in Hardy-Weinberg equilibrium. Our results indicate an over-representation of the Pro allele of the p53 gene in women with IRM, giving support to the theory that p53 has a potential role during pregnancy.

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

    Directory of Open Access Journals (Sweden)

    Sathidpak Nantasanti

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

  11. Gain-of-function mutant p53 activates small GTPase Rac1 through SUMOylation to promote tumor progression.

    Science.gov (United States)

    Yue, Xuetian; Zhang, Cen; Zhao, Yuhan; Liu, Juan; Lin, Alan W; Tan, Victor M; Drake, Justin M; Liu, Lianxin; Boateng, Michael N; Li, Jun; Feng, Zhaohui; Hu, Wenwei

    2017-08-15

    Tumor suppressor p53 is frequently mutated in human cancer. Mutant p53 often promotes tumor progression through gain-of-function (GOF) mechanisms. However, the mechanisms underlying mutant p53 GOF are not well understood. In this study, we found that mutant p53 activates small GTPase Rac1 as a critical mechanism for mutant p53 GOF to promote tumor progression. Mechanistically, mutant p53 interacts with Rac1 and inhibits its interaction with SUMO-specific protease 1 (SENP1), which in turn inhibits SENP1-mediated de-SUMOylation of Rac1 to activate Rac1. Targeting Rac1 signaling by RNAi, expression of the dominant-negative Rac1 (Rac1 DN), or the specific Rac1 inhibitor NSC23766 greatly inhibits mutant p53 GOF in promoting tumor growth and metastasis. Furthermore, mutant p53 expression is associated with enhanced Rac1 activity in clinical tumor samples. These results uncover a new mechanism for Rac1 activation in tumors and, most importantly, reveal that activation of Rac1 is an unidentified and critical mechanism for mutant p53 GOF in tumorigenesis, which could be targeted for therapy in tumors containing mutant p53. © 2017 Yue et al.; Published by Cold Spring Harbor Laboratory Press.

  12. Profiling of oligosaccharides and p53 gene mutation in Filipino breast tumors

    International Nuclear Information System (INIS)

    Deocaris, Custer C.; De Vera, Azucena C.; Magno, Jose Donato A.; Cruz, Michael Joseph B.; Prodigalidad, Abelardo-Alan T.; Jacinto, Sonia D.

    2010-01-01

    Majority of patients are diagnosed with benign tumors, however, such benign tumors can progress to an invasive disease. Since carbohydrate-mediated cell-cell adhesion and proliferative potential play crucial roles in tumorigenesis and tumor aggressive behavior, we analyzed the qualitative changes in oligosaccharide expression and analyzed for presence of mutation in the tumor suppressor p53 gene, the most mutated gene in all human cancers. Forty-three (43) breast tumors were screened for p53 mutation in exons 2-11 using polymerase chain reaction (PCR)-amplification coupled to temporal temperature gradient electrophoresis (TTGE). Paraffin-embedded tissues were stained with biotinylated-glycoproteins containing the following sugar groups: mannose (Man), lactose (Lac), fucoidan (Fuc), N-acetyl-glucosamine (GlcNac), N-acetyl-b-galactosamine (GalNAc) and hyaluronic acid (Hya). Expression of carbohydrate receptors was significantly elevated (p=0.003) in malignant compared with benign tumors, particularly at receptors for GalNAc, lac and Fuc. No change in overall glycan signatures using our panel of neoglycoconjugates was noted when grouped according to p53 mutation status in both benign and malignant cases. Although the prognostic value of carbohydrate-receptors in breast cancer has not been validated to date, our results indicate that benign and malignant tumors can be defined by their affinities to our battery of neoglyconjugates. However, result from our reverse lectin histochemistry failed to correlated glycan signature with presence of p53 mutations. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Pelletier, J.; Beckwith, B.; Bardeesy, N. [Loma Linda Univ., CA (United States)]|[McGill Univ., Montreal (Canada)

    1994-09-01

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

  14. Combined cytotoxic effects of tumor necrosis factor-alpha with various cytotoxic agents in tumor cell lines that are drug resistant due to mutated p53

    NARCIS (Netherlands)

    Sleijfer, S; Le, T. K. P.; de Jong, S.; Timmer-Bosscha, H; Withoff, S; Mulder, NH

    Several studies suggest that tumor necrosis factor-alpha (TNF) is able to overcome drug resistance in tumors. Whether TNF is able to do so in tumor cell lines that are drug resistant due to a mutation in the tumor suppressor gene p53 is unclear. Therefore, we studied the in vitro cytotoxic effects

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

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    Dadi Jiang

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

  16. PRIMA-1Met/APR-246 induces apoptosis and tumor growth delay in small cell lung cancer expressing mutant p53

    DEFF Research Database (Denmark)

    Zandi, Roza; Selivanova, Galina; Christensen, Camilla Laulund

    2011-01-01

    Small cell lung cancer (SCLC) is a highly malignant disease with poor prognosis, necessitating the need to develop new and efficient treatment modalities. PRIMA-1(Met) (p53-dependent reactivation of massive apoptosis), also known as APR-246, is a small molecule, which restores tumor suppressor...... function to mutant p53 and induces cancer cell death in various cancer types. Since p53 is mutated in more than 90% of SCLC, we investigated the ability of PRIMA-1(Met) to induce apoptosis and inhibit tumor growth in SCLC with different p53 mutations....

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

    International Nuclear Information System (INIS)

    Ando, Koji; Oki, Eiji; Saeki, Hiroshi; Yan, Zhao; Tsuda, Yasuo; Hidaka, Gen; Kasagi, Yuta; Otsu, Hajime; Kawano, Hiroyuki; Kitao, Hiroyuki; Morita, Masaru; Maehara, Yoshihiko

    2015-01-01

    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 p53 was observed in 88 (59.5%) tumors. Tumors with positive p53 staining showed malignant features compared to negative tumors. Mutation of TP53 gene was observed in 29 (19.6%) tumors with higher age and differentiated type. In positive p53 tumors, two types could be distinguished; aberrant type and scattered type. With comparison to TP53 gene mutation analysis, all the scattered type had wild-type TP53 gene (P = 0.0003). SNP-CGH array showed that scattered-type tumors had no change in the structure of chromosome 17. P53-scattered-type staining tumors may reflect a functionally active nonmutated TP53 gene. In interpretation of p53 immunohistochemistry staining, distinguishing p53-positive tumors by their staining pattern may be important in gastric cancer

  18. Loss of p19(Arf facilitates the angiogenic switch and tumor initiation in a multi-stage cancer model via p53-dependent and independent mechanisms.

    Directory of Open Access Journals (Sweden)

    Danielle B Ulanet

    2010-08-01

    Full Text Available The Arf tumor suppressor acts as a sensor of oncogenic signals, countering aberrant proliferation in large part via activation of the p53 transcriptional program, though a number of p53-independent functions have been described. Mounting evidence suggests that, in addition to promoting tumorigenesis via disruptions in the homeostatic balance between cell proliferation and apoptosis of overt cancer cells, genetic alterations leading to tumor suppressor loss of function or oncogene gain of function can also incite tumor development via effects on the tumor microenvironment. In a transgenic mouse model of multi-stage pancreatic neuroendocrine carcinogenesis (PNET driven by inhibition of the canonical p53 and Rb tumor suppressors with SV40 large T-antigen (Tag, stochastic progression to tumors is limited in part by a requirement for initiation of an angiogenic switch. Despite inhibition of p53 by Tag in this mouse PNET model, concomitant disruption of Arf via genetic knockout resulted in a significantly accelerated pathway to tumor formation that was surprisingly not driven by alterations in tumor cell proliferation or apoptosis, but rather via earlier activation of the angiogenic switch. In the setting of a constitutional p53 gene knockout, loss of Arf also accelerated tumor development, albeit to a lesser degree. These findings demonstrate that Arf loss of function can promote tumorigenesis via facilitating angiogenesis, at least in part, through p53-independent mechanisms.

  19. Essentials in clinical application of p53 for tumors intervention-example of liver cancer

    International Nuclear Information System (INIS)

    Guan Yongsong; He Qing

    2008-01-01

    Recombinant human adenovirus p53 (Ad-p53)injection has been used for treating tumors in combination with several local therapeutic methods. Taking liver cancer as an example, this article introduces the combination of Ad-p53 in procedures of interventional therapy. Mechanisms of their effects are emphasized to pursue an optimal synergism in killing tumors. Intratumoral injection is suggested as the first choice of Ad- p53 administration with the least recommended dosage for a single tumor. The optimal time for intervention of liver cancer is supposed to be 2 to 5 days after the administration of Ad-p53. There are several theories on the therapeutic method taking p53 as a target, some of them are contradictional; therefore one has to select either activating or inhibiting the p53 pathway beforehand. For advanced malignancies, the selection should be cautious for appropriater cases from the proper candidates. (authors)

  20. Disruption of focal adhesion kinase and p53 interaction with small molecule compound R2 reactivated p53 and blocked tumor growth

    International Nuclear Information System (INIS)

    Golubovskaya, Vita M; Ho, Baotran; Zheng, Min; Magis, Andrew; Ostrov, David; Morrison, Carl; Cance, William G

    2013-01-01

    Focal Adhesion Kinase (FAK) is a 125 kDa non-receptor kinase that plays a major role in cancer cell survival and metastasis. We performed computer modeling of the p53 peptide containing the site of interaction with FAK, predicted the peptide structure and docked it into the three-dimensional structure of the N-terminal domain of FAK involved in the complex with p53. We screened small molecule compounds that targeted the site of the FAK-p53 interaction and identified compounds (called Roslins, or R compounds) docked in silico to this site. By different assays in isogenic HCT116p53 + / + and HCT116 p53 - / - cells we identified a small molecule compound called Roslin 2 (R2) that bound FAK, disrupted the binding of FAK and p53 and decreased cancer cell viability and clonogenicity in a p53-dependent manner. In addition, dual-luciferase assays demonstrated that the R2 compound increased p53 transcriptional activity that was inhibited by FAK using p21, Mdm-2, and Bax-promoter targets. R2 also caused increased expression of p53 targets: p21, Mdm-2 and Bax proteins. Furthermore, R2 significantly decreased tumor growth, disrupted the complex of FAK and p53, and up-regulated p21 in HCT116 p53 + / + but not in HCT116 p53 - / - xenografts in vivo. In addition, R2 sensitized HCT116p53 + / + cells to doxorubicin and 5-fluorouracil. Thus, disruption of the FAK and p53 interaction with a novel small molecule reactivated p53 in cancer cells in vitro and in vivo and can be effectively used for development of FAK-p53 targeted cancer therapy approaches

  1. ER, p53 and MIB-1 are significantly associated with malignant phyllodes tumor

    Directory of Open Access Journals (Sweden)

    Nurhayati H Munawer

    2012-12-01

    Full Text Available Background: Phyllodes tumors (PT are rare. We evaluated the expression status of ER, Bcl2, p53, and MIB-1 protein in these tumors. Methods: One hundred and ninety-three tumors were examined using immunohistochemistry on tissue microarray. Results: ERβ (p <0.001, and p53 (p=0.006 in the stromal component were associated with tumor size. p53 expression was significantly associated with both epithelial and stro­mal components of malignant PTs (p<0.05. In PT, the decreased expressions of p53 and MIB-1 were significantly different with positive Bcl2 protein expression in epi­thelial component (p=0.000. Besides, MIB-1 was also found to be associated with ERα and ERβ in stromal component (p=0.000. Conclusion: The expression of p53 with tumor size and histological grade in PTs may increase risk for malignancy.

  2. Cdk5 phosphorylates non-genotoxically overexpressed p53 following inhibition of PP2A to induce cell cycle arrest/apoptosis and inhibits tumor progression

    Directory of Open Access Journals (Sweden)

    Kumari Ratna

    2010-07-01

    Full Text Available Abstract Background p53 is the most studied tumor suppressor and its overexpression may or may not cause cell death depending upon the genetic background of the cells. p53 is degraded by human papillomavirus (HPV E6 protein in cervical carcinoma. Several stress activated kinases are known to phosphorylate p53 and, among them cyclin dependent kinase 5 (Cdk5 is one of the kinase studied in neuronal cell system. Recently, the involvement of Cdk5 in phosphorylating p53 has been shown in certain cancer types. Phosphorylation at specific serine residues in p53 is essential for it to cause cell growth inhibition. Activation of p53 under non stress conditions is poorly understood. Therefore, the activation of p53 and detection of upstream kinases that phosphorylate non-genotoxically overexpressed p53 will be of therapeutic importance for cancer treatment. Results To determine the non-genotoxic effect of p53; Tet-On system was utilized and p53 inducible HPV-positive HeLa cells were developed. p53 overexpression in HPV-positive cells did not induce cell cycle arrest or apoptosis. However, we demonstrate that overexpressed p53 can be activated to upregulate p21 and Bax which causes G2 arrest and apoptosis, by inhibiting protein phosphatase 2A. Additionally, we report that the upstream kinase cyclin dependent kinase 5 interacts with p53 to phosphorylate it at Serine20 and Serine46 residues thereby promoting its recruitment on p21 and bax promoters. Upregulation and translocation of Bax causes apoptosis through intrinsic mitochondrial pathway. Interestingly, overexpressed activated p53 specifically inhibits cell-growth and causes regression in vivo tumor growth as well. Conclusion Present study details the mechanism of activation of p53 and puts forth the possibility of p53 gene therapy to work in HPV positive cervical carcinoma.

  3. Both p53-PUMA/NOXA-Bax-mitochondrion and p53-p21cip1 pathways are involved in the CDglyTK-mediated tumor cell suppression

    International Nuclear Information System (INIS)

    Yu, Zhendong; Wang, Hao; Zhang, Libin; Tang, Aifa; Zhai, Qinna; Wen, Jianxiang; Yao, Li; Li, Pengfei

    2009-01-01

    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.

  4. Both p53-PUMA/NOXA-Bax-mitochondrion and p53-p21cip1 pathways are involved in the CDglyTK-mediated tumor cell suppression

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhendong, E-mail: zdyu@hotmail.com [Department of Clinical laboratory, Peking University Shenzhen Hospital, Guangdong (China); Wang, Hao [Department of pathology, The Chinese University of Hong Kong, Hong Kong (China); Zhang, Libin; Tang, Aifa; Zhai, Qinna; Wen, Jianxiang; Yao, Li [Department of Clinical laboratory, Peking University Shenzhen Hospital, Guangdong (China); Li, Pengfei, E-mail: lipengfei@cuhk.edu.hk [Department of pathology, The Chinese University of Hong Kong, Hong Kong (China)

    2009-09-04

    CDglyTK fusion suicide gene has been well characterized to effectively kill tumor cells. However, the exact mechanism and downstream target genes are not fully understood. In our study, we found that CDglyTK/prodrug treatment works more efficiently in p53 wild-type (HONE1) cells than in p53 mutant (CNE1) cells. We then used adenovirus-mediated gene delivery system to either knockdown or overexpress p53 and its target genes in these cells. Consistent results showed that both p53-PUMA/NOXA/Bcl2-Bax and p53-p21 pathways contribute to the CDglyTK induced tumor cell suppression. Our work for the first time addressed the role of p53 related genes in the CDglyTK/prodrug system.

  5. Clinical and pathological associations with p53 tumour-suppressor gene mutations and expression of p21WAF1/Cip1 in colorectal carcinoma

    NARCIS (Netherlands)

    Slebos, R. J.; Baas, I. O.; Clement, M.; Polak, M.; Mulder, J. W.; van den Berg, F. M.; Hamilton, S. R.; Offerhaus, G. J.

    1996-01-01

    Inactivation of the p53 tumour-suppressor gene is common in a wide variety of human neoplasms. In the majority of cases, single point mutations in the protein-encoding sequence of p53 lead to positive immunohistochemistry (IHC) for the p53 protein, and are accompanied by loss of the wild-type

  6. Structure and stability insights into tumour suppressor p53 evolutionary related proteins.

    Directory of Open Access Journals (Sweden)

    Bruno Pagano

    Full Text Available The p53 family of genes and their protein products, namely, p53, p63 and p73, have over one billion years of evolutionary history. Advances in computational biology and genomics are enabling studies of the complexities of the molecular evolution of p53 protein family to decipher the underpinnings of key biological conditions spanning from cancer through to various metabolic and developmental disorders and facilitate the design of personalised medicines. However, a complete understanding of the inherent nature of the thermodynamic and structural stability of the p53 protein family is still lacking. This is due, to a degree, to the lack of comprehensive structural information for a large number of homologous proteins and to an incomplete knowledge of the intrinsic factors responsible for their stability and how these might influence function. Here we investigate the thermal stability, secondary structure and folding properties of the DNA-binding domains (DBDs of a range of proteins from the p53 family using biophysical methods. While the N- and the C-terminal domains of the p53 family show sequence diversity and are normally targets for post-translational modifications and alternative splicing, the central DBD is highly conserved. Together with data obtained from Molecular Dynamics simulations in solution and with structure based homology modelling, our results provide further insights into the molecular properties of evolutionary related p53 proteins. We identify some marked structural differences within the p53 family, which could account for the divergence in biological functions as well as the subtleties manifested in the oligomerization properties of this family.

  7. Acetylation Is Crucial for p53-Mediated Ferroptosis and Tumor Suppression

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    Shang-Jui Wang

    2016-10-01

    Full Text Available Although previous studies indicate that loss of p53-mediated cell cycle arrest, apoptosis, and senescence does not completely abrogate its tumor suppression function, it is unclear how the remaining activities of p53 are regulated. Here, we have identified an acetylation site at lysine K98 in mouse p53 (or K101 for human p53. Whereas the loss of K98 acetylation (p53K98R alone has very modest effects on p53-mediated transactivation, simultaneous mutations at all four acetylation sites (p534KR: K98R+ 3KR[K117R+K161R+K162R] completely abolish its ability to regulate metabolic targets, such as TIGAR and SLC7A11. Notably, in contrast to p533KR, p534KR is severely defective in suppressing tumor growth in mouse xenograft models. Moreover, p534KR is still capable of inducing the p53-Mdm2 feedback loop, but p53-dependent ferroptotic responses are markedly abrogated. Together, these data indicate the critical role of p53 acetylation in ferroptotic responses and its remaining tumor suppression activity.

  8. The Role of Tumor Protein 53 Mutations in Common Human Cancers and Targeting the Murine Double Minute 2–P53 Interaction for Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Tayebeh Hamzehloie

    2012-03-01

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

  9. Doxycyclin induces p53 expression in SaOs (osteosarcoma) cell line ...

    African Journals Online (AJOL)

    The p53 tumour suppressor gene plays an important role in preventing cancer development. This study determined if p53 can be induced in osteosarcoma cell line upon treatment ... represent an important component of the p53 tumor suppressor pathway. Keywords: Tumor suppressor, oncogene, mdm2, cyclinE, apoptosis ...

  10. p53 and PCNA Expression in Keratocystic Odontogenic Tumors Compared with Selected Odontogenic Cysts

    Science.gov (United States)

    Seyedmajidi, Maryam; Nafarzadeh, Shima; Siadati, Sepideh; Shafaee, Shahryar; Bijani, Ali; Keshmiri, Nazanin

    2013-01-01

    p53 and PCNA expression in keratocystic odontogenic tumors compared with selected odontogenic cysts Summary: The aim of this study was to evaluate p53 and PCNA expression in different odontogenic lesions regarding their different clinical behaviors. Slices prepared from 94 paraffin-embedded tissue blocks (25 radicular cysts (RC), 23 dentigerous cysts (DC), 23 keratocystic odontogenic tumors (KCOT) and 23 calcifying cystic odontogenic tumors (CCOT)) were stained with p53 and PCNA antibodies using immunohistochemistry procedure. The highest level of p53 expression was in the basal layer of RC, and the highest level of PCNA expression was in the suprabasal layer of KCOT. The differences of p53 expression in basal and suprabasal layers as well as PCNA expression in the suprabasal layer were significant but there was no significant difference in PCNA expression in the basal layer of these lesions. The expression of p53 in the basal layer of RC was higher than in other cysts. This may be due to intensive inflammatory infiltration. Also, the high level of PCNA expression in the suprabasal layer of KCOT may justify its neoplastic nature and tendency to recurrence. KCOT and calcifying cystic odontogenic tumors did not show similar expression of studied biomarkers. PMID:24551811

  11. Immunohistochemical Expression of Ki67 and p53 in Wilms Tumor and Its Relationship with Tumor Histology and Stage at Presentation

    Science.gov (United States)

    Krishna, O. H. Radhika; Kayla, Geetha; Abdul Aleem, Mohammed; Malleboyina, Ramani; Reddy Kota, Ramesh

    2016-01-01

    Aim. Evaluate tumor proliferation marker (Ki67) and p53 tumor suppressor marker in Wilms tumor and correlate with histology, anaplasia, and staging. Design. Prospective, hospital based study conducted at a tertiary pediatric referral centre in south India. Setting. Wilms tumor is the most common childhood renal malignancy worldwide. Anaplasia on histology is associated with treatment resistance but not with aggressiveness clinical presentation. Chemotherapy for Wilms tumor is based on histology and staging. Most patients respond to current chemotherapy protocol. However, a small fraction relapses or metastasizes. Affordable prognostic markers are needed for histopathological evaluation of this tumor. Subjects. Cases of histologically confirmed Wilms tumor over five years. Cases after chemotherapy were excluded as the immunostaining was inconsistent in necrotic areas. Methods. The clinical and radiological findings of 31 cases of Wilms tumor were documented at a tertiary pediatric referral hospital over five years. In addition to Hematoxylin and Eosin staining, Ki67 proliferation index and p53 expression were correlated with tumor histology and staging. Results. Age incidence was 3–8 years with female preponderance. Significant correlation was noted between Ki67 proliferation index and tumor staging. p53 expression was not useful in stratification of Wilms tumor. Conclusion. Ki67 was cost-effective immunohistochemical marker for prognostication of pediatric Wilms tumor. PMID:26904359

  12. Immunohistochemical Expression of Ki67 and p53 in Wilms Tumor and Its Relationship with Tumor Histology and Stage at Presentation

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    O. H. Radhika Krishna

    2016-01-01

    Full Text Available Aim. Evaluate tumor proliferation marker (Ki67 and p53 tumor suppressor marker in Wilms tumor and correlate with histology, anaplasia, and staging. Design. Prospective, hospital based study conducted at a tertiary pediatric referral centre in south India. Setting. Wilms tumor is the most common childhood renal malignancy worldwide. Anaplasia on histology is associated with treatment resistance but not with aggressiveness clinical presentation. Chemotherapy for Wilms tumor is based on histology and staging. Most patients respond to current chemotherapy protocol. However, a small fraction relapses or metastasizes. Affordable prognostic markers are needed for histopathological evaluation of this tumor. Subjects. Cases of histologically confirmed Wilms tumor over five years. Cases after chemotherapy were excluded as the immunostaining was inconsistent in necrotic areas. Methods. The clinical and radiological findings of 31 cases of Wilms tumor were documented at a tertiary pediatric referral hospital over five years. In addition to Hematoxylin and Eosin staining, Ki67 proliferation index and p53 expression were correlated with tumor histology and staging. Results. Age incidence was 3–8 years with female preponderance. Significant correlation was noted between Ki67 proliferation index and tumor staging. p53 expression was not useful in stratification of Wilms tumor. Conclusion. Ki67 was cost-effective immunohistochemical marker for prognostication of pediatric Wilms tumor.

  13. Evaluation of nuclear unrest and p53 immunostaining in Wilms' tumor.

    Science.gov (United States)

    Salama, Asmaa; Kamel, Ahmad

    2011-03-01

    Nuclear unrest is a term applied to Wilms' tumors (WT) that show nuclear abnormalities close to anaplasia but without abnormal mitoses. p53 is claimed to be associated with anaplasia and poor prognosis. This study was undertaken to evaluate the clinical significance of nuclear unrest and p53 immunostaining in Wilms' tumor. This is a retrospective study of 63 patients who presented at NCI with Wilms' tumors, and underwent preoperative chemotherapy followed by nephrectomy. Histopathologic assessment and p53 immunohistochemistry were done. WT with nuclear unrest grade III closely resembled anaplastic tumors and both of them (group 1) constituted 19% of cases. Group 1 constituted 29% of cases showing blastema dominant morphology compared to 9.4% of cases without blastema dominant morphology with significant statistical difference (p=0.047). Almost 83% of cases that achieved 1st complete remission were stages I, II and III, while 17% were stages IV and V with significant statistical difference (p<0.001). Stage affected the 3-year relapse-free-survival (RFS) significantly (p=0.014) as it was more in stages I, II and III than in stages IV and V (75.4% versus 50%). Blastema dominant morphology and high risk state significantly lowered the 3-year overall survival (OS) into 54.8% in comparison to 80.9% for cases with non-blastema dominant morphology (p=0.042). Regarding p53 immunohistochemistry, group 1 tumors showed positive p53 more than group 2 with significant statistical difference (p=0.014). p53 Positive immunostaining was significantly associated with high risk nephroblastoma (p=0.004). Tumor stage and blastema dominant morphology are potent prognostic factors. p53 is linked to blastema dominant morphology. WT with nuclear unrest grade III closely resembles anaplastic WT. It may be appropriate to group tumors with nuclear unrest grade III with anaplastic histology regarding treatment stratification. Copyright © 2011. Published by Elsevier B.V.

  14. Evaluation of nuclear unrest and p53 immunostaining in Wilms' tumor

    International Nuclear Information System (INIS)

    Salama, A.; Kamel, A.

    2011-01-01

    Nuclear unrest is a term applied to Wilms' tumors (WT) that show nuclear abnormalities close to anaplasia but without abnormal mitoses. p53 is claimed to be associated with anaplasia and poor prognosis. This study was undertaken to evaluate the clinical significance of nuclear unrest and p53 immunostaining in Wilms' tumor. Material and methods: This is a retrospective study of 63 patients who presented at NCI with Wilms' tumors, and underwent preoperative chemotherapy followed by nephrectomy. Histopathologic assessment and p53 immunohistochemistry were done. Results: WT with nuclear unrest grade III closely resembled anaplastic tumors and both of them (group 1) constituted 19% of cases. Group 1 constituted 29% of cases showing blastema dominant morphology compared to 9.4% of cases without blastema dominant morphology with significant statistical difference (p = 0.047). Almost 83% of cases that achieved 1st complete remission were stages I, II and III, while 17% were stages IV and V with significant statistical difference (p < 0.001). Stage affected the 3-year relapse-free-survival (RFS) significantly (p = 0.014) as it was more in stages I, II and III than in stages IV and V (75.4% versus 50%). Blastema dominant morphology and high risk state significantly lowered the 3-year overall survival (OS) into 54.8% in comparison to 80.9% for cases with non-blastema dominant morphology (p = 0.042). Regarding p53 immunohistochemistry, group 1 tumors showed positive p53 more than group 2 with significant statistical difference (p = 0.014). p53 Positive immunostaining was significantly associated with high risk nephroblastoma (p = 0.004). Conclusion: Tumor stage and blastema dominant morphology are potent prognostic factors. p53 is linked to blastema dominant morphology. WT with nuclear unrest grade III closely resembles anaplastic WT. It may be appropriate to group tumors with nuclear unrest grade III with anaplastic histology regarding treatment stratification

  15. Expression of CD44 and P53 in renal cell carcinoma: Association with tumor subtypes

    Directory of Open Access Journals (Sweden)

    Farahnaz Noroozinia

    2014-01-01

    Full Text Available Renal cell carcinoma (RCC is a common malignancy of the kidney and accurate prediction of prognosis is valuable for the design of adjuvant therapy and counseling and effective scheduling of follow-up visits. Molecular genetic investigations of CD44 and P53 in RCC may be helpful in this regard. We studied the CD44 and P53 expressions semi-quantitatively on paraffin-embedded specimens of 64 RCC patients (37 male/27 female who underwent surgery from 2003 to 2008 by immunohistochemistry and analyzed the correlation of P53 and CD44 expression in RCC and outcome. Thirteen of 64 (20.3% specimens were P53 positive, 30/64 (46.9% were CD44 positive and five tumors with positive P53 expressed CD44 protein (P = 0.5. A statistically significant correlation was not found between CD44 and P53 expression (P = 0.5 and age (P = 0.07, sex (P= 0.3, tumor size (P = 0.7, grade (P = 0.23, vascular invasion (P = 1.00 and ureteral invasion (P = 1.00. Furthermore, a significant correlation was not found between P53 expression with age (P = 0.3, sex (P = 0.7, tumor size (P = 0.7, grade (P = 0.1, vascular inva-sion (P = 1.00 and ureteral invasion (P = 1.00. According to our findings, only P53 expression is generally accompanied by non-conventional subtype tumor.

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

    Science.gov (United States)

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

    2006-02-01

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

  17. Limited role of murine ATM in oncogene-induced senescence and p53-dependent tumor suppression.

    Directory of Open Access Journals (Sweden)

    Alejo Efeyan

    Full Text Available Recent studies in human fibroblasts have provided a new general paradigm of tumor suppression according to which oncogenic signaling produces DNA damage and this, in turn, results in ATM/p53-dependent cellular senescence. Here, we have tested this model in a variety of murine experimental systems. Overexpression of oncogenic Ras in murine fibroblasts efficiently induced senescence but this occurred in the absence of detectable DNA damage signaling, thus suggesting a fundamental difference between human and murine cells. Moreover, lung adenomas initiated by endogenous levels of oncogenic K-Ras presented abundant senescent cells, but undetectable DNA damage signaling. Accordingly, K-Ras-driven adenomas were also senescent in Atm-null mice, and the tumorigenic progression of these lesions was only modestly accelerated by Atm-deficiency. Finally, we have examined chemically-induced fibrosarcomas, which possess a persistently activated DNA damage response and are highly sensitive to the activity of p53. We found that the absence of Atm favored genomic instability in the resulting tumors, but did not affect the persistent DNA damage response and did not impair p53-dependent tumor suppression. All together, we conclude that oncogene-induced senescence in mice may occur in the absence of a detectable DNA damage response. Regarding murine Atm, our data suggest that it plays a minor role in oncogene-induced senescence or in p53-dependent tumor suppression, being its tumor suppressive activity probably limited to the maintenance of genomic stability.

  18. Phosphorylation of the Mdm2 oncoprotein by the c-Abl tyrosine kinase regulates p53 tumor suppression and the radiosensitivity of mice.

    Science.gov (United States)

    Carr, Michael I; Roderick, Justine E; Zhang, Hong; Woda, Bruce A; Kelliher, Michelle A; Jones, Stephen N

    2016-12-27

    The p53 tumor suppressor acts as a guardian of the genome by preventing the propagation of DNA damage-induced breaks and mutations to subsequent generations of cells. We have previously shown that phosphorylation of the Mdm2 oncoprotein at Ser394 by the ATM kinase is required for robust p53 stabilization and activation in cells treated with ionizing radiation, and that loss of Mdm2 Ser394 phosphorylation leads to spontaneous tumorigenesis and radioresistance in Mdm2 S394A mice. Previous in vitro data indicate that the c-Abl kinase phosphorylates Mdm2 at the neighboring residue (Tyr393) in response to DNA damage to regulate p53-dependent apoptosis. In this present study, we have generated an Mdm2 mutant mouse (Mdm2 Y393F ) to determine whether c-Abl phosphorylation of Mdm2 regulates the p53-mediated DNA damage response or p53 tumor suppression in vivo. The Mdm2 Y393F mice develop accelerated spontaneous and oncogene-induced tumors, yet display no defects in p53 stabilization and activity following acute genotoxic stress. Although apoptosis is unaltered in these mice, they recover more rapidly from radiation-induced bone marrow ablation and are more resistant to whole-body radiation-induced lethality. These data reveal an in vivo role for c-Abl phosphorylation of Mdm2 in regulation of p53 tumor suppression and bone marrow failure. However, c-Abl phosphorylation of Mdm2 Tyr393 appears to play a lesser role in governing Mdm2-p53 signaling than ATM phosphorylation of Mdm2 Ser394. Furthermore, the effects of these phosphorylation events on p53 regulation are not additive, as Mdm2 Y393F/S394A mice and Mdm2 S394A mice display similar phenotypes.

  19. Allelic and haplotype frequencies of the p53 polymorphisms in brain tumor patients

    Czech Academy of Sciences Publication Activity Database

    Biroš, Erik; Kalina, I.; Kohút, A.; Bogyiová, E.; Šalagovič, J.; Šulla, I.

    2002-01-01

    Roč. 51, č. 1 (2002), s. 59-64 ISSN 0862-8408 R&D Projects: GA MŽP SI/340/1/97 Institutional research plan: CEZ:AV0Z5039906 Keywords : Brain tumor * Susceptibility * p53 Subject RIV: FD - Oncology ; Hematology Impact factor: 0.984, year: 2002

  20. Pure versus combined Merkel cell carcinomas: immunohistochemical evaluation of cellular proteins (p53, Bcl-2, and c-kit) reveals significant overexpression of p53 in combined tumors.

    Science.gov (United States)

    Lai, Jonathan H; Fleming, Kirsten E; Ly, Thai Yen; Pasternak, Sylvia; Godlewski, Marek; Doucette, Steve; Walsh, Noreen M

    2015-09-01

    Merkel cell polyomavirus is of oncogenic significance in approximately 80% of Merkel cell carcinomas. Morphological subcategories of the tumor differ in regard to viral status, the rare combined type being uniformly virus negative and the predominant pure type being mainly virus positive. Indications that different biological subsets of the tumor exist led us to explore this diversity. In an Eastern Canadian cohort of cases (75 patients; mean age, 76 years [range, 43-91]; male/female ratio, 43:32; 51 [68%] pure and 24 [34%] combined tumors), we semiquantitatively compared the immunohistochemical expression of 3 cellular proteins (p53, Bcl-2, and c-kit) in pure versus combined groups. Viral status was known in a subset of cases. The significant overexpression of p53 in the combined group (mean [SD], 153.8 [117.8] versus 121.6 [77.9]; P = .01) and the increased epidermal expression of this protein (p53 patches) in the same group lend credence to a primary etiologic role for sun damage in these cases. Expression of Bcl-2 and c-kit did not differ significantly between the 2 morphological groups. A relative increase in c-kit expression was significantly associated with a virus-negative status (median [interquartile range], 100 [60-115] versus 70 [0-100]; P = .03). Emerging data reveal divergent biological pathways in Merkel cell carcinoma, each with a characteristic immunohistochemical profile. Virus-positive tumors (all pure) exhibit high retinoblastoma protein and low p53 expression, whereas virus-negative cases (few pure and all combined) show high p53 and relatively high c-kit expression. The potential biological implications of this dichotomy call for consistent stratification of these tumors in future studies. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. ER, p53 and MIB-1 are significantly associated with malignant phyllodes tumor.

    Science.gov (United States)

    Munawer, Nurhayati H; Md Zin, Reena; Md Ali, Siti-Aishah; Muhammad, Rohaizak; Ali, Jasmi; Das, Srijit

    2012-01-01

    Fibroadenomas (FA) are common while phyllodes tumors (PT) are rare and both tumors are composed of epithelial and stromal components. We evaluated the expression status of ER, Bc12, p53, and MIB-1 protein in these tumors. One hundred and ninety-three tumors comprising of 117 FAs and 76 PTs were examined using immunohistochemistry on tissue microarray. The mean age of patients with FA was 28.5 years while the mean ages of patients with benign, borderline and malignant PTs were 41.7, 48.6 and 42.1 years, respectively. Also all types of PTs were large (>Scm). ER showed a strong nuclear staining in the epithelial component of all tumors while ER/3 immunoreactivity was detected in both the epithelial and stromal components ofF A and PT. ER/β (pcomponent were associated with tumor size. p53 expression was significantly associated with both the epithelial and stromal components of malignant PTs (pcomponent (p=0.000). In addition, MIB-1 was also found to be associated with ER and ER/3 in the stromal component (p=0.000). The expression of p53 with tumor size and histological grade in PT may increase the risk for malignancy.

  2. Pu-erh Tea Inhibits Tumor Cell Growth by Down-Regulating Mutant p53

    Science.gov (United States)

    Zhao, Lanjun; Jia, Shuting; Tang, Wenru; Sheng, Jun; Luo, Ying

    2011-01-01

    Pu-erh tea is a kind of fermented tea with the incorporation of microorganisms’ metabolites. Unlike green tea, the chemical characteristics and bioactivities of Pu-erh tea are still not well understood. Using water extracts of Pu-erh tea, we analyzed the tumor cell growth inhibition activities on several genetically engineered mouse tumor cell lines. We found that at the concentration that did not affect wild type mouse embryo fibroblasts (MEFs) growth, Pu-erh tea extracts could inhibit tumor cell growth by down-regulated S phase and cause G1 or G2 arrest. Further study showed that Pu-erh tea extracts down-regulated the expression of mutant p53 in tumor cells at the protein level as well as mRNA level. The same concentration of Pu-erh tea solution did not cause p53 stabilization or activation of its downstream pathways in wild type cells. We also found that Pu-erh tea treatment could slightly down-regulate both HSP70 and HSP90 protein levels in tumor cells. These data revealed the action of Pu-erh tea on tumor cells and provided the possible mechanism for Pu-erh tea action, which explained its selectivity in inhibiting tumor cells without affecting wild type cells. Our data sheds light on the application of Pu-erh tea as an anti-tumor agent with low side effects. PMID:22174618

  3. Implication of p53-dependent cellular senescence related gene, TARSH in tumor suppression

    International Nuclear Information System (INIS)

    Wakoh, Takeshi; Uekawa, Natsuko; Terauchi, Kunihiko; Sugimoto, Masataka; Ishigami, Akihito; Shimada, Jun-ichi; Maruyama, Mitsuo

    2009-01-01

    A novel target of NESH-SH3 (TARSH) was identified as a cellular senescence related gene in mouse embryonic fibroblasts (MEFs) replicative senescence, the expression of which has been suppressed in primary clinical lung cancer specimens. However, the molecular mechanism underlying the regulation of TARSH involved in pulmonary tumorigenesis remains unclear. Here we demonstrate that the reduction of TARSH gene expression by short hairpin RNA (shRNA) system robustly inhibited the MEFs proliferation with increase in senescence-associated β-galactosidase (SA-β-gal) activity. Using p53 -/- MEFs, we further suggest that this growth arrest by loss of TARSH is evoked by p53-dependent p21 Cip1 accumulation. Moreover, we also reveal that TARSH reduction induces multicentrosome in MEFs, which is linked in chromosome instability and tumor development. These results suggest that TARSH plays an important role in proliferation of replicative senescence and may serve as a trigger of tumor development.

  4. Tumour suppressor protein p53 regulates the stress activated bilirubin oxidase cytochrome P450 2A6

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Hao, E-mail: hao.hu1@uqconnect.edu.au [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Yu, Ting, E-mail: t.yu2@uq.edu.au [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Arpiainen, Satu, E-mail: Satu.Juhila@orion.fi [Institute of Biomedicine, Department of Pharmacology and Toxicology and Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu (Finland); Lang, Matti A., E-mail: m.lang@uq.edu.au [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Hakkola, Jukka, E-mail: Jukka.hakkola@oulu.fi [Institute of Biomedicine, Department of Pharmacology and Toxicology and Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu (Finland); Abu-Bakar, A' edah, E-mail: a.abubakar@uq.edu.au [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia)

    2015-11-15

    Human cytochrome P450 (CYP) 2A6 enzyme has been proposed to play a role in cellular defence against chemical-induced oxidative stress. The encoding gene is regulated by various stress activated transcription factors. This paper demonstrates that p53 is a novel transcriptional regulator of the gene. Sequence analysis of the CYP2A6 promoter revealed six putative p53 binding sites in a 3 kb proximate promoter region. The site closest to transcription start site (TSS) is highly homologous with the p53 consensus sequence. Transfection with various stepwise deletions of CYP2A6-5′-Luc constructs – down to − 160 bp from the TSS – showed p53 responsiveness in p53 overexpressed C3A cells. However, a further deletion from − 160 to − 74 bp, including the putative p53 binding site, totally abolished the p53 responsiveness. Electrophoretic mobility shift assay with a probe containing the putative binding site showed specific binding of p53. A point mutation at the binding site abolished both the binding and responsiveness of the recombinant gene to p53. Up-regulation of the endogenous p53 with benzo[α]pyrene – a well-known p53 activator – increased the expression of the p53 responsive positive control and the CYP2A6-5′-Luc construct containing the intact p53 binding site but not the mutated CYP2A6-5′-Luc construct. Finally, inducibility of the native CYP2A6 gene by benzo[α]pyrene was demonstrated by dose-dependent increases in CYP2A6 mRNA and protein levels along with increased p53 levels in the nucleus. Collectively, the results indicate that p53 protein is a regulator of the CYP2A6 gene in C3A cells and further support the putative cytoprotective role of CYP2A6. - Highlights: • CYP2A6 is an immediate target gene of p53. • Six putative p53REs located on 3 kb proximate CYP2A6 promoter region. • The region − 160 bp from TSS is highly homologous with the p53 consensus sequence. • P53 specifically bind to the p53RE on the − 160 bp region. • HNF4

  5. A tumor-targeting p53 nanodelivery system limits chemoresistance to temozolomide prolonging survival in a mouse model of glioblastoma multiforme.

    Science.gov (United States)

    Kim, Sang-Soo; Rait, Antonina; Kim, Eric; Pirollo, Kathleen F; Chang, Esther H

    2015-02-01

    Development of temozolomide (TMZ) resistance contributes to the poor prognosis for glioblastoma multiforme (GBM) patients. It was previously demonstrated that delivery of exogenous wild-type tumor suppressor gene p53 via a tumor-targeted nanocomplex (SGT-53) which crosses the blood-brain barrier could sensitize highly TMZ-resistant GBM tumors to TMZ. Here we assessed whether SGT-53 could inhibit development of TMZ resistance. SGT-53 significantly chemosensitized TMZ-sensitive human GBM cell lines (U87 and U251), in vitro and in vivo. Furthermore, in an intracranial GBM tumor model, two cycles of concurrent treatment with systemically administered SGT-53 and TMZ inhibited tumor growth, increased apoptosis and most importantly, significantly prolonged median survival. In contrast TMZ alone had no significant effect on median survival compared to a single cycle of TMZ. These results suggest that combining SGT-53 with TMZ appears to limit development of TMZ resistance, prolonging its anti-tumor effect and could be a more effective therapy for GBM. Using human glioblastoma multiforma cell lines, this research team demonstrated that the delivery of exogenous wild-type tumor suppressor gene p53 via a tumor-targeted nanocomplex limited the development of temozolomide resistance and prolonged its anti-tumor effect, which may enable future human application of this or similar techniques. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Isoform-specific interactions of the von Hippel-Lindau tumor suppressor protein

    OpenAIRE

    Minervini, Giovanni; Mazzotta, Gabriella M.; Masiero, Alessandro; Sartori, Elena; Corr?, Samantha; Potenza, Emilio; Costa, Rodolfo; Tosatto, Silvio C. E.

    2015-01-01

    Deregulation of the von Hippel-Lindau tumor suppressor protein (pVHL) is considered one of the main causes for malignant renal clear-cell carcinoma (ccRCC) insurgence. In human, pVHL exists in two isoforms, pVHL19 and pVHL30 respectively, displaying comparable tumor suppressor abilities. Mutations of the p53 tumor suppressor gene have been also correlated with ccRCC insurgence and ineffectiveness of treatment. A recent proteomic analysis linked full length pVHL30 with p53 pathway regulation t...

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

    International Nuclear Information System (INIS)

    Ota, Ichiro; Yane, Katsunari; Yuki, Kazue; Kanata, Hirokazu; Hosoi, Hiroshi; Miyahara, Hiroshi

    2001-01-01

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

  8. Tumor-promoting phorbol ester transiently down-modulates the p53 level and blocks the cell cycle

    DEFF Research Database (Denmark)

    Skouv, J.; Jensen, P O; Forchhammer, J

    1994-01-01

    Activation of the protein kinase C signaling pathway by tumor-promoting phorbol esters, such as 4 beta-phorbol 12-myristate 13-acetate (PMA), induced a decrease in the level of p53 mRNA in several serum-starved human cell lines. Also, the tumor-promoting phosphatase inhibitor okadaic acid induced...... a decrease in the p53 mRNA level in the cell lines. Normal diploid as well as various tumor cell lines were tested. Two tumor cell lines, HeLa and A549, both containing the wild-type p53 gene, but very different levels of p53 protein, were studied in detail. In both cell lines, the level of p53 m......RNA was minimal after 9 h of exposure to PMA. After approximately 120 h, the p53 mRNA level was similar to the pretreatment level. PMA induced a similar transient decrease in the level of p53 protein in the A549 cell line. The decrease in the p53 mRNA level could not be explained by changes in the transcriptional...

  9. Regulation of Mdmx and its role in the p53 pathway

    NARCIS (Netherlands)

    Meulmeester, Erik

    2006-01-01

    The p53 protein is an important tumor suppressor that acts as a key regulator of the integrity of the genome. Two essential regulators of the p53 protein are Mdm2 and its homologue Mdmx. Like Mdm2, Mdmx represses p53-induced transcription. However, Mdmx cannot ubiquitinate or degrade p53 opposed to

  10. p53-dependent non-coding RNA networks in chronic lymphocytic leukemia

    NARCIS (Netherlands)

    Blume, C. J.; Hotz-Wagenblatt, A.; Hüllein, J.; Sellner, L.; Jethwa, A.; Stolz, T.; Slabicki, M.; Lee, K.; Sharathchandra, A.; Benner, A.; Dietrich, S.; Oakes, C. C.; Dreger, P.; te Raa, D.; Kater, A. P.; Jauch, A.; Merkel, O.; Oren, M.; Hielscher, T.; Zenz, T.

    2015-01-01

    Mutations of the tumor suppressor p53 lead to chemotherapy resistance and a dismal prognosis in chronic lymphocytic leukemia (CLL). Whereas p53 targets are used to identify patient subgroups with impaired p53 function, a comprehensive assessment of non-coding RNA targets of p53 in CLL is missing. We

  11. Magnetite nanoparticles inhibit tumor growth and upregulate the expression of p53/p16 in Ehrlich solid carcinoma bearing mice.

    Directory of Open Access Journals (Sweden)

    Heba Bassiony

    Full Text Available BACKGROUND: Magnetite nanoparticles (MNPs have been widely used as contrast agents and have promising approaches in cancer treatment. In the present study we used Ehrlich solid carcinoma (ESC bearing mice as a model to investigate MNPs antitumor activity, their effect on expression of p53 and p16 genes as an indicator for apoptotic induction in tumor tissues. METHOD: MNPs coated with ascorbic acid (size: 25.0±5.0 nm were synthesized by co-precipitation method and characterized. Ehrlich mice model were treated with MNPs using 60 mg/Kg day by day for 14 injections; intratumorally (IT or intraperitoneally (IP. Tumor size, pathological changes and iron content in tumor and normal muscle tissues were assessed. We also assessed changes in expression levels of p53 and p16 genes in addition to p53 protein level by immunohistochemistry. RESULTS: Our results revealed that tumor growth was significantly reduced by IT and IP MNPs injection compared to untreated tumor. A significant increase in p53 and p16 mRNA expression was detected in Ehrlich solid tumors of IT and IP treated groups compared to untreated Ehrlich solid tumor. This increase was accompanied with increase in p53 protein expression. It is worth mentioning that no significant difference in expression of p53 and p16 could be detected between IT ESC and control group. CONCLUSION: MNPs might be more effective in breast cancer treatment if injected intratumorally to be directed to the tumor tissues.

  12. Hormonal control of p53 and chemoprevention

    International Nuclear Information System (INIS)

    Jerry, D Joseph; Minter, Lisa M; Becker, Klaus A; Blackburn, Anneke C

    2002-01-01

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

  13. 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

    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

  14. Tumor protein 53-induced nuclear protein 1 (TP53INP1 enhances p53 function and represses tumorigenesis

    Directory of Open Access Journals (Sweden)

    Jeyran eShahbazi

    2013-05-01

    Full Text Available Tumor protein 53-induced nuclear protein 1 (TP53INP1 is a stress-induced p53 target gene whose expression is modulated by transcription factors such as p53, p73 and E2F1. TP53INP1 gene encodes two isoforms of TP53INP1 proteins, TP53INP1α and TP53INP1β, both of which appear to be key elements in p53 function. When associated with homeodomain-interacting protein kinase-2 (HIPK2, TP53INP1 phosphorylates p53 protein at Serine 46, enhances p53 protein stability and its transcriptional activity, leading to transcriptional activation of p53 target genes such as p21, PIG-3 and MDM2, cell growth arrest and apoptosis upon DNA damage stress. The anti-proliferative and pro-apoptotic activities of TP53INP1 indicate that TP53INP1 has an important role in cellular homeostasis and DNA damage response. Deficiency in TP53INP1 expression results in increased tumorigenesis; while TP53INP1 expression is repressed during early stages of cancer by factors such as miR-155. This review aims to summarize the roles of TP53INP1 in blocking tumor progression through p53-dependant and p53-independent pathways, as well as the elements which repress TP53INP1 expression, hence highlighting its potential as a therapeutic target in cancer treatment.

  15. Zoledronic acid produces combinatory anti-tumor effects with cisplatin on mesothelioma by increasing p53 expression levels.

    Directory of Open Access Journals (Sweden)

    Shinya Okamoto

    Full Text Available We examined anti-tumor effects of zoledronic acid (ZOL, one of the bisphosphonates agents clinically used for preventing loss of bone mass, on human mesothelioma cells bearing the wild-type p53 gene. ZOL-treated cells showed activation of caspase-3/7, -8 and -9, and increased sub-G1 phase fractions. A combinatory use of ZOL and cisplatin (CDDP, one of the first-line anti-cancer agents for mesothelioma, synergistically or additively produced the cytotoxicity on mesothelioma cells. Moreover, the combination achieved greater anti-tumor effects on mesothelioma developed in the pleural cavity than administration of either ZOL or CDDP alone. ZOL-treated cells as well as CDDP-treated cells induced p53 phosphorylation at Ser 15, a marker of p53 activation, and up-regulated p53 protein expression levels. Down-regulation of p53 levels with siRNA however did not influence the ZOL-mediated cytotoxicity but negated the combinatory effects by ZOL and CDDP. In addition, ZOL treatments augmented cytotoxicity of adenoviruses expressing the p53 gene on mesothelioma. These data demonstrated that ZOL-mediated augmentation of p53, which was not linked with ZOL-induced cytotoxicity, played a role in the combinatory effects with a p53 up-regulating agent, and suggests a possible clinical use of ZOL to mesothelioma with anti-cancer agents.

  16. Tumorigenic potential of pituitary tumor transforming gene (PTTG in vivo investigated using a transgenic mouse model, and effects of cross breeding with p53 (+/− transgenic mice

    Directory of Open Access Journals (Sweden)

    Fong Miranda Y

    2012-11-01

    . Tumorigenesis is a multi-step process, often requiring multiple oncogenes and/or inactivation of tumor suppressor genes. Therefore, to understand the contribution of p53 to PTTG induced tumorigenesis, we crossbred TgPTTG to p53+/− mice and maintained those 8 to 10 months. TgPTTG/p53+/− animals developed sarcomas faster than p53+/− alone as well as different tumor types in addition to cervical carcinomas in situ in 10 out of 17 females. Conclusions We conclude that while PTTG is a functional transforming oncogene, it requires an additional partner to effectively promote tumorigenesis through the loss of p53 include or between function or modulation.

  17. RITA (Reactivating p53 and Inducing Tumor Apoptosis) is efficient against TP53abnormal myeloma cells independently of the p53 pathway.

    Science.gov (United States)

    Surget, Sylvanie; Descamps, Géraldine; Brosseau, Carole; Normant, Vincent; Maïga, Sophie; Gomez-Bougie, Patricia; Gouy-Colin, Nadège; Godon, Catherine; Béné, Marie C; Moreau, Philippe; Le Gouill, Steven; Amiot, Martine; Pellat-Deceunynck, Catherine

    2014-06-14

    The aim of this study was to evaluate the efficacy of the p53-reactivating drugs RITA and nutlin3a in killing myeloma cells. A large cohort of myeloma cell lines (n = 32) and primary cells (n = 21) was used for this study. This cohort contained cell lines with various TP53 statuses and primary cells with various incidences of deletion of chromosome 17. Apoptosis was evaluated using flow cytometry with Apo2.7 staining of the cell lines or via the loss of the myeloma-specific marker CD138 in primary cells. Apoptosis was further confirmed by the appearance of a subG1 peak and the activation of caspases 3 and 9. Activation of the p53 pathway was monitored using immunoblotting via the expression of the p53 target genes p21, Noxa, Bax and DR5. The involvement of p53 was further studied in 4 different p53-silenced cell lines. Both drugs induced the apoptosis of myeloma cells. The apoptosis that was induced by RITA was not related to the TP53 status of the cell lines or the del17p status of the primary samples (p = 0.52 and p = 0.80, respectively), and RITA did not commonly increase the expression level of p53 or p53 targets (Noxa, p21, Bax or DR5) in sensitive cells. Moreover, silencing of p53 in two TP53(mutated) cell lines failed to inhibit apoptosis that was induced by RITA, which confirmed that RITA-induced apoptosis in myeloma cells was p53 independent. In contrast, apoptosis induced by nutlin3a was directly linked to the TP53 status of the cell lines and primary samples (p RITA, in contrast to nutlin3a, effectively induced apoptosis in a subset of MM cells independently of p53. The findings and could be of interest for patients with a 17p deletion, who are resistant to current therapies.

  18. Synergistic anti-tumor effects of nitroreductase mutants and p53

    Directory of Open Access Journals (Sweden)

    Mahboobeh Razmkhah

    2014-01-01

    Conclusion: Combination of T41L/F70A NTR with p53 may have more advantages for treatment of different types of cancers compared to the other NTRs and p53 alone. The present study results may open new windows for getting desired outcome in gene therapy of different types of cancer.

  19. Associations between Polycyclic Aromatic Hydrocarbon-Related Exposures and p53 Mutations in Breast Tumors

    Czech Academy of Sciences Publication Activity Database

    Mordukhovich, I.; Rössner ml., Pavel; Terry, M. B.; Santella, R.; Zhang, Y.J.; Hibshoosh, H.; Memeo, L.; Mansukhani, M.; Long, CH.M.; Garbowski, G.; Agrawal, M.; Gaudet, M. M.; Steck, S. E.; Sagiv, S. K.; Eng, S. M.; Teitelbaum, S. L.; Neugut, A. I.; Conway-Dorsey, K.; Gammon, M. D.

    2010-01-01

    Roč. 118, č. 4 (2010), s. 511-518 ISSN 0091-6765 Institutional research plan: CEZ:AV0Z50390512 Keywords : breast cancer * p53 mutation * p53 overexpression Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 6.087, year: 2010

  20. Antigen-specific immunotherapy in ovarian cancer and p53 as tumor antigen

    NARCIS (Netherlands)

    Vermeij, Renee; Leffers, Ninke; Melief, Cornelis J.; Daemen, Toos; Nijman, Hans W.

    This review discusses the results of different immunization strategies, identifies possible drawbacks in study design and provides potential solutions for augmentation of clinical efficacy. A potential target for cancer immunotherapy is p53, as approximately 50% of ovarian cancer cells carry p53

  1. A novel p53 mutational hotspot in skin tumors from UV-irradiated Xpc mutant mice alters transactivation functions.

    Science.gov (United States)

    Inga, Alberto; Nahari, Dorit; Velasco-Miguel, Susana; Friedberg, Errol C; Resnick, Michael A

    2002-08-22

    A mutation in codon 122 of the mouse p53 gene resulting in a T to L amino acid substitution (T122-->L) is frequently associated with skin cancer in UV-irradiated mice that are both homozygous mutant for the nucleotide excision repair (NER) gene Xpc (Xpc(-/-)) and hemizygous mutant for the p53 gene. We investigated the functional consequences of the mouse T122-->L mutation when expressed either in mammalian cells or in the yeast Saccharomyces cerevisiae. Similar to a non-functional allele, high expression of the T122-->L allele in p53(-/-) mouse embryo fibroblasts and human Saos-2 cells failed to suppress growth. However, the T122-->L mutant p53 showed wild-type transactivation levels with Bax and MDM2 promoters when expressed in either cell type and retained transactivation of the p21 and the c-Fos promoters in one cell line. Using a recently developed rheostatable p53 induction system in yeast we assessed the T122-->L transactivation capacity at low levels of protein expression using 12 different p53 response elements (REs). Compared to wild-type p53 the T122-->L protein manifested an unusual transactivation pattern comprising reduced and enhanced activity with specific REs. The high incidence of the T122-->L mutant allele in the Xpc(-/-) background suggests that both genetic and epigenetic conditions may facilitate the emergence of particular functional p53 mutations. Furthermore, the approach that we have taken also provides for the dissection of functions that may be retained in many p53 tumor alleles.

  2. Promoter methylation of RASSF1A and DAPK and mutations of K-ras, p53, and EGFR in lung tumors from smokers and never-smokers

    International Nuclear Information System (INIS)

    Liu, Yang; Gao, Weimin; Siegfried, Jill M; Weissfeld, Joel L; Luketich, James D; Keohavong, Phouthone

    2007-01-01

    Epidemiological studies indicate that some characteristics of lung cancer among never-smokers significantly differ from those of smokers. Aberrant promoter methylation and mutations in some oncogenes and tumor suppressor genes are frequent in lung tumors from smokers but rare in those from never-smokers. In this study, we analyzed promoter methylation in the ras-association domain isoform A (RASSF1A) and the death-associated protein kinase (DAPK) genes in lung tumors from patients with primarily non-small cell lung cancer (NSCLC) from the Western Pennsylvania region. We compare the results with the smoking status of the patients and the mutation status of the K-ras, p53, and EGFR genes determined previously on these same lung tumors. Promoter methylation of the RASSF1A and DAPK genes was analyzed by using a modified two-stage methylation-specific PCR. Data on mutations of K-ras, p53, and EGFR were obtained from our previous studies. The RASSF1A gene promoter methylation was found in tumors from 46.7% (57/122) of the patients and was not significantly different between smokers and never-smokers, but was associated significantly in multiple variable analysis with tumor histology (p = 0.031) and marginally with tumor stage (p = 0.063). The DAPK gene promoter methylation frequency in these tumors was 32.8% (40/122) and did not differ according to the patients' smoking status, tumor histology, or tumor stage. Multivariate analysis adjusted for age, gender, smoking status, tumor histology and stage showed that the frequency of promoter methylation of the RASSF1A or DAPK genes did not correlate with the frequency of mutations of the K-ras, p53, and EGFR gene. Our results showed that RASSF1A and DAPK genes' promoter methylation occurred frequently in lung tumors, although the prevalence of this alteration in these genes was not associated with the smoking status of the patients or the occurrence of mutations in the K-ras, p53 and EGFR genes, suggesting each of

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

    International Nuclear Information System (INIS)

    Oya, N.; Zoelzer, F.; Werner, F.; Streffer, C.

    2003-01-01

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

  4. Status and advances of p53-gene therapy and radiotherapy in malignant tumor

    International Nuclear Information System (INIS)

    Duan Xin; Chinese Academy of Sciences, Beijing; Zhang Hong

    2006-01-01

    Cancer treatment is one of the most important fields in medical research. All strategies such as radio-therapy, chemotherapy, surgery, and gene-based therapy have their own advantages and disadvantages. Nowadays, a novel method which combined p53-gene therapy with radiotherapy plays an important role in the field of cancer research. This review summarized the current state of combined therapies of p53-gene therapy and radiotherapy, possible mechanism and recent progress. (authors)

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

    International Nuclear Information System (INIS)

    Perryman, L.A.; Blair, J.M.; Kingsley, E.A.; Szymanska, B.; Ow, K.T.; Wen, V.W.; MacKenzie, K.L.; Vermeulen, P.B.; Jackson, P.; Russell, P.J.

    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 expressing F134L and R273H grew slower than controls, and were associated with decreased necrosis and apoptosis, but not hypoxia. Interestingly, hypoxia levels were increased in tumors expressing M237L. There was less proliferation in F134L-bearing tumors compared to control, but this was not statistically significant. Angiogenesis was decreased in tumors expressing F134L and R273H compared with M237L, or controls. Conditioned medium from F134L tumors inhibited growth of normal human umbilical-vein endothelial cells but not telomerase-immortalized bone marrow endothelial cells. F134L tumor supernatants showed lower levels of VEGF and endostatin compared with supernatants from tumors expressing other mutants. Our results support the possibility that decreased angiogenesis might account for reduced growth rate of tumor cells expressing the F134L p53 mutation

  6. Chemical Variations on the p53 Reactivation Theme

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    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.

  7. Immunohistochemical analysis of P53 protein in odontogenic cysts

    Science.gov (United States)

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

    2010-01-01

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

  8. p53 in differentiation of thyroid cancer

    International Nuclear Information System (INIS)

    Seyama, Toshio; Ito, Takashi; Akiyama, Mitoshi; Hayashi, Yuzo; Dohi, Kiyohiko.

    1993-01-01

    P53 is a tumor suppressor gene with such a recessive nature and is inactivated in many carcinomas. DNA was extracted from 10 primary papillary adenocarcinomas and eight undifferentiated carcinomas of the thyroid, using three 5 μm sliced paraffin segments, and then amplified by PCR. The products were analyzed for mutations in the p53 gene exons 5 to 8 by the direct sequencing method and for allelic deletion by the RFLP method. In five human thyroid carcinomas, DNA was extracted from each tissue and analyzed. Mutations in the p53 gene exons 5 to 8 and p53 gene deletions were not detected in the 10 papillary adenocarcinomas, mutations were detected in seven of eight cases and allelic deletions was detected in three of the five cases examined. In each of the five cases which had both differentiated and undifferentiated tissues in the same tumor, p53 gene mutations were not detected in the differentiated tissues while mutations and gene deletions were detected in the undifferentiated sections. The p53 gene was analyzed using paraffin-embedded tissues by the combined use of the direct sequencing and PCR methods and by the RFLP method. It was found that the progression of human thyroid carcinoma is closely related to the p53 genetic changes. Furthermore, the analysis of differentiated and undifferentiated tissues in the same tumor showed that human undifferentiated thyroid carcinomas develop from differentiated carcinomas. (J.P.N.)

  9. OTUD5 regulates p53 stability by deubiquitinating p53.

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    Judong Luo

    Full Text Available 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.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.As a novel deubiquitinating enzyme for p53, OTUD5 is required for the stabilization and the activation of a p53 response.

  10. Reactivity of p53 protein in canine transmissible venereal tumor Reatividade da proteína P53 no tumor venéreo transmissível canino

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    J.V. Moro

    2010-04-01

    Full Text Available The expression of p53 protein was evaluated in canine transmissible venereal tumor (CTVT, as following: natural occurrence (n=8; resistant to chemotherapy (n=4; and allogeneic transplanted in progression (n=8, stable (n=8, and regression (n=8stages. The collected specimens were submitted to GM1 immunohistochemical reaction. Results showed a mean percentage of immunomarked cells around 18.6% in CTVT of natural occurrence, 23.8% in CTVT resistant to chemotherapy, 22.9% in allogeneic transplanted CTVT in both progression and stable stages, and 35.8% in transplanted CTVT in regression stage. The results suggest that there is a functional abnormality in p53 gene and its products in the studied tumors; although, it is not possible to correlate the percentage of cells marked by p53 and a prognosis.A expressão da proteína p53 foi avaliada em espécimes de tumor venéreo transmissível canino (TVT de ocorrência natural (n=8; resistente à quimioterapia (n=4 e transplantado em cão nas fases de progressão tumoral (n=8, de latência (n=8 e de regressão (n=8. Os espécimes foram submetidos à reação de imunoistoquímica. Os resultados mostraram porcentagem média de células imunomarcadas de 18,6% no TVT de ocorrência natural, de 23,8% no TVT refratário, 22,9% nos TVTs transplantados nas fases de progressão e latência e de 35,8% na fase de regressão. Os resultados sugerem que há uma anormalidade funcional no gene P53 e seus produtos nos tumores estudados, apesar de não ser possível correlacionar a porcentagem de células marcadas pelo p53 ao prognóstico.

  11. S100A4 interacts with p53 in the nucleus and promotes p53 degradation.

    Science.gov (United States)

    Orre, L M; Panizza, E; Kaminskyy, V O; Vernet, E; Gräslund, T; Zhivotovsky, B; Lehtiö, J

    2013-12-05

    S100A4 is a small calcium-binding protein that is commonly overexpressed in a range of different tumor types, and it is widely accepted that S100A4 has an important role in the process of cancer metastasis. In vitro binding assays has shown that S100A4 interacts with the tumor suppressor protein p53, indicating that S100A4 may have additional roles in tumor development. In the present study, we show that endogenous S100A4 and p53 interact in complex samples, and that the interaction increases after inhibition of MDM2-dependent p53 degradation using Nutlin-3A. Further, using proximity ligation assay, we show that the interaction takes place in the cell nucleus. S100A4 knockdown experiments in two p53 wild-type cell lines, A549 and HeLa, resulted in stabilization of p53 protein, indicating that S100A4 is promoting p53 degradation. Finally, we demonstrate that S100A4 knockdown leads to p53-dependent cell cycle arrest and increased cisplatin-induced apoptosis. Thus, our data add a new layer to the oncogenic properties of S100A4 through its inhibition of p53-dependent processes.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  13. p53-dependent inhibition of TrxR1 contributes to the tumor-specific induction of apoptosis by RITA.

    Science.gov (United States)

    Hedström, Elisabeth; Eriksson, Sofi; Zawacka-Pankau, Joanna; Arnér, Elias S J; Selivanova, Galina

    2009-11-01

    Thioredoxin reductase 1 (TrxR1) is a key regulator in many redox-dependent cellular pathways, and is often overexpressed in cancer. Several studies have identified TrxR1 as a potentially important target for anticancer therapy. The low molecular weight compound RITA (NSC 652287) binds p53 and induces p53-dependent apoptosis. Here we found that RITA also targets TrxR1 by non-covalent binding, followed by inhibition of its activity in vitro and by inhibition of TrxR activity in cancer cells. Interestingly, a novel approximately 130 kDa form of TrxR1, presumably representing a stable covalently linked dimer, and an increased generation of reactive oxygen species (ROS) were induced by RITA in cancer cells in a p53-dependent manner. Similarly, the gold-based TrxR inhibitor auranofin induced apoptosis related to oxidative stress, but independently of p53 and without apparent induction of the approximately 130 kDa form of TrxR1. In contrast to the effects observed in cancer cells, RITA did not inhibit TrxR or ROS formation in normal fibroblasts (NHDF). The inhibition of TrxR1 can sensitize tumor cells to agents that induce oxidative stress and may directly trigger cell death. Thus, our results suggest that a unique p53-dependent effect of RITA on TrxR1 in cancer cells might synergize with p53-dependent induction of pro-apoptotic genes and oxidative stress, thereby leading to a robust induction of cancer cell death, without affecting non-transformed cells.

  14. The Parkinson disease-related protein DJ-1 counteracts mitochondrial impairment induced by the tumour suppressor protein p53 by enhancing endoplasmic reticulum-mitochondria tethering.

    Science.gov (United States)

    Ottolini, Denis; Calì, Tito; Negro, Alessandro; Brini, Marisa

    2013-06-01

    DJ-1 was first identified as an oncogene. More recently, mutations in its gene have been found causative for autosomal recessive familial Parkinson disease. Numerous studies support the DJ-1 role in the protection against oxidative stress and maintenance of mitochondria structure; however, the mechanism of its protective function remains largely unknown. We investigated whether mitochondrial Ca(2+) homeostasis, a key parameter in cell physiology, could be a target for DJ-1 action. Here, we show that DJ-1 modulates mitochondrial Ca(2+) transients induced upon cell stimulation with an 1,4,5-inositol-tris-phosphate agonist by favouring the endoplasmic reticulum (ER)-mitochondria tethering. A reduction of DJ-1 levels results in mitochondria fragmentation and decreased mitochondrial Ca(2+) uptake in stimulated cells. To functionally couple these effects with the well-recognized cytoprotective role of DJ-1, we investigated its action in respect to the tumour suppressor p53. p53 overexpression in HeLa cells impairs their ability to accumulate Ca(2+) in the mitochondrial matrix, causes alteration of the mitochondrial morphology and reduces ER-mitochondria contact sites. Mitochondrial impairments are independent from Drp1 activation, since the co-expression of the dominant negative mutant of Drp1 failed to abolish them. DJ-1 overexpression prevents these alterations by re-establishing the ER-mitochondria tethering. Similarly, the co-expression of the pro-fusion protein Mitofusin 2 blocks the effects induced by p53 on mitochondria, confirming that the modulation of the ER-mitochondria contact sites is critical to mitochondria integrity. Thus, the impairment of ER-mitochondria communication, as a consequence of DJ-1 loss-of-function, may be detrimental for mitochondria-related processes and be at the basis of mitochondrial dysfunction observed in Parkinson disease.

  15. Conformational detection of p53's oligomeric state by FlAsH Fluorescence

    OpenAIRE

    Webber, Tawnya M.; Allen, Andrew C.; Ma, Wai Kit; Molloy, Rhett G.; Kettelkamp, Charisse N.; Dow, Caitlin A.; Gage, Matthew J.

    2009-01-01

    The p53 tumor suppressor protein is a critical checkpoint in prevention of tumor formation, and the function of p53 is dependent on proper formation of the active tetramer. In vitro studies have shown that p53 binds DNA most efficiently as a tetramer, though inactive p53 is predicted to be monomeric in vivo. We demonstrate that FlAsH binding can be used to distinguish between oligomeric states of p53, providing a potential tool to explore p53 oligomerization in vivo. The FlAsH tetra-cysteine ...

  16. Analysis of the K-ras and p53 pathways in x-ray-induced lung tumors in the rat

    Energy Technology Data Exchange (ETDEWEB)

    Belinsky, S.A.; Middleton, S.K.; Hahn, F.F.; Nikula, K.J. [Inhalation Toxicology Research Inst., Albuquerque, NM (United States); Picksley, S.M. [Medical Sciences Inst., Dundee (United Kingdom)

    1996-04-01

    The risk from exposure to low-dose radiation in conjunction with cigarette smoking has not been estimated due in part to lmited knowledge surrounding the molecular mechanisms underlying radiation-induced cancers. The purpose of this investigation was to determine the frequency for alterations in genes within the K-ras and p53 signal and cell cycle regulatory pathways, respectively, in X-ray-induced lung tumors in the F344/N rat. These tumors were examined for genetic alterations in the K-ras, c-raf-1, p53, mdm2 and cip1 genes. No K-ras mutations were detected by sequencing in 18 squamous cell carcinomas (SCCs) or 17 adenocarcinomas. However, using a K-ras codon 12 mutation selection assay, a codon 12 GGT {r_arrow} GAT mutation was detected in one SCC, suggesting that activation of the K-ras proto-oncogene is both a rare and late event. Single-strand conformation polymorphism (SSCP) analysis of the kinase-binding domain of the c-raf-1 gene did not detect any polymorphisms. Three of 18 SCCs but none of the adenocarcinomas showed p53 nuclear immunoreactivity. Single-strand conformation polymorphism analysis of exons 4-9 of the p53 gene detected only an exon 9 mutation in one SCC. Mutations were not detected in the three SCCs with immunoreactive p53 protein. No amplification of the mdm2 gene was detected; however, nuclear mdm2 immunoreactivity was present in one of the three SCCs that stained positive for the p53 protein. The complete cDNA of the rat cip1 gene comprising 810 bases was cloned and sequenced. The frequency of somatic mutations in exon 2 of the cip1 gene was determined by SSCP analysis. No alterations in electrophoretic mobility were detected. The results of this investigation indicate that alterations in the K-ras and p53 pathways do not play a major role in the genesis of X-ray-induced lung tumors in the rat. 49 refs., 5 figs.

  17. Effect of interventional treatment with p53 on the invasion and metastasis of VX2 liver tumor in experimental rabbits

    International Nuclear Information System (INIS)

    Li Caixia; Feng Yan; Gu Tao; Li Chunmei

    2010-01-01

    Objective: To investigate the effect of interventional treatment with p53 on the invasion and metastasis of VX2 liver tumor in experimental rabbits. Methods: VX2 carcinoma cells were surgically implanted into the left hepatic lobe in 48 New Zealand white rabbits, and the rabbit hepatic carcinoma models were thus established. The rabbits were randomly divided into 4 groups with 12 rabbits in each group. After hepatic arterial catheterization was completed physiological saline (control group), Lipiodol (Group A), Ad-p53 (Group B) and Lipiodol+Ad-p53 (Group C) were respectively infused into the rabbits of four groups via common hepatic artery. One week after the procedure the rabbits were sacrificed and the livers were removed for the determination of matrix metalloprotein-2 (MMP-2), proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF) of the tumor with immunohistochemistry technique. Results: The tumor growth in study groups (group A, B and C) was markedly suppressed, which was significantly different in comparison with that in control group (P 0.05). The positive rates of MMP-2, PCNA and VEGF in group B and C were significantly lower than those in control group (P < 0.05). The positive rates of MMP-2, PCNA and VEGF of the rabbits with metastasis were markedly higher than those without metastasis(P < 0.05). MMP-2 bore a certain relationship with VEGF and PCNA (P < 0.05). Conclusion: The increase of the positive rates of MMP-2, PCNA and VEGF indicates that the tumor possesses higher possibility for developing metastasis, proliferation and vascular formation. The interventional treatment with Adp53 or Lipiodol+Ad-p53 can inhibit the growth, metastasis and vascular formation of VX2 liver tumor in experimental rabbits. (J Intervent Radiol, 2010, 19 : 800-804) (authors)

  18. Targeting p53 by small molecules in hematological malignancies

    OpenAIRE

    Saha, Manujendra N; Qiu, Lugui; Chang, Hong

    2013-01-01

    p53 is a powerful tumor suppressor and is an attractive cancer therapeutic target. A breakthrough in cancer research came from the discovery of the drugs which are capable of reactivating p53 function. Most anti-cancer agents, from traditional chemo- and radiation therapies to more recently developed non-peptide small molecules exert their effects by enhancing the anti-proliferative activities of p53. Small molecules such as nutlin, RITA, and PRIMA-1 that can activate p53 have shown their ant...

  19. Inhibition of p53 acetylation by INHAT subunit SET/TAF-Iβ represses p53 activity.

    Science.gov (United States)

    Kim, Ji-Young; Lee, Kyu-Sun; Seol, Jin-Ee; Yu, Kweon; Chakravarti, Debabrata; Seo, Sang-Beom

    2012-01-01

    The tumor suppressor p53 responds to a wide variety of cellular stress signals. Among potential regulatory pathways, post-translational modifications such as acetylation by CBP/p300 and PCAF have been suggested for modulation of p53 activity. However, exactly how p53 acetylation is modulated remains poorly understood. Here, we found that SET/TAF-Iβ inhibited p300- and PCAF-mediated p53 acetylation in an INHAT (inhibitor of histone acetyltransferase) domain-dependent manner. SET/TAF-Iβ interacted with p53 and repressed transcription of p53 target genes. Consequently, SET/TAF-Iβ blocked both p53-mediated cell cycle arrest and apoptosis in response to cellular stress. Using different apoptosis analyses, including FACS, TUNEL and BrdU incorporation assays, we also found that SET/TAF-Iβ induced cellular proliferation via inhibition of p53 acetylation. Furthermore, we observed that apoptotic Drosophila eye phenotype induced by either dp53 overexpression or UV irradiation was rescued by expression of dSet. Inhibition of dp53 acetylation by dSet was observed in both cases. Our findings provide new insights into the regulation of stress-induced p53 activation by HAT-inhibiting histone chaperone SET/TAF-Iβ.

  20. Molecular biology III - Oncogenes and tumor suppressor genes

    International Nuclear Information System (INIS)

    Giaccia, Amato J.

    1996-01-01

    Purpose: The purpose of this course is to introduce to radiation oncologists the basic concepts of tumorigenesis, building on the information that will be presented in the first and second part of this series of lectures. Objective: Our objective is to increase the current understanding of radiation oncologists with the process of tumorigenesis, especially focusing on genes that are altered in many tumor types that are potential candidates for novel molecular strategies. As strategies to treat cancer of cancer are becoming more sophisticated, it will be important for both the practitioner and academician to develop a basic understanding of the function of cancer 'genes'. This will be the third in a series of refresher courses that are meant to address recent advances in Cancer Biology in a way that both clinicians without previous knowledge of molecular biology or experienced researchers will find interesting. The lecture will begin with a basic overview of tumorigenesis; methods of detecting chromosome/DNA alterations, approaches used to isolate oncogenes and tumor suppressor genes, and their role in cell killing by apoptosis. Special attention will be given to oncogenes and tumor suppressor genes that are modulated by ionizing radiation and the tumor microenvironment. We will relate the biology of oncogenes and tumor suppressor genes to basic aspects of radiation biology that would be important in clinical practice. Finally, we will review recent studies on the prognostic significance of p53 mutations and apoptosis in tumor specimens. The main point of this lecture is to relate both researcher and clinician what are the therapeutic ramifications of oncogene and tumor suppressor gene mutations found in human neoptasia

  1. Malignant chondroblastoma presenting as a recurrent pelvic tumor with DNA aneuploidy and p53 mutation as supportive evidence of malignancy

    Energy Technology Data Exchange (ETDEWEB)

    Ostrowski, M.L. [Department of Pathology and Laboratory Medicine, Baylor College of Medicine, The Methodist Hospital and Texas Children' s Hospital, Houston, Texas (United States); Department of Pathology and Laboratory Medicine, Houston, TX (United States). Methodist Hospital; Johnson, M.E. [Department of Orthopedic Surgery, Baylor College of Medicine, The Methodist Hospital and Texas Children' s Hospital, Houston, Texas (United States); Truong, L.D.; Hicks, M.J.; Spjut, H.J. [Department of Pathology and Laboratory Medicine, Baylor College of Medicine, The Methodist Hospital and Texas Children' s Hospital, Houston, Texas (United States); Smith, F.E. [Department of Oncology, Baylor College of Medicine, The Methodist Hospital and Texas Children' s Hospital, Houston, Texas (United States)

    1999-11-01

    We report a rare case of malignant chondroblastoma, which presented in a 47-year-old man as a recurrent tumor, 18 years following wide excision of a typical pelvic chondroblastoma. Radiologic studies of the recurrent tumor showed a large, lytic, destructive lesion of the right pelvic bones and femur, with a pathologic fracture of the latter, a large pelvic soft tissue mass, and multiple pulmonary metastases. Biopsy tissue showed typical features of chondroblastoma, but also increased nuclear atypia, hyperchromasia, and pleomorphism, compared to the original tumor, and, most significantly, abnormal mitotic figures. Immunohistochemical studies of the recurrent tumor revealed p53 mutation and extensive proliferative activity, and flow cytometric studies showed DNA aneuploidy, none of which was present in the original tumor. The patient received chemotherapy and radiation, but died of disease eight months after presentation. We also review chondroblastoma in general, to assign this unusual lesion to a tumor subtype. (orig.)

  2. Identification of proteins that regulate radiation-induced apoptosis in murine tumors with wild type p53

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    Seong, Jinsil; Oh, Hae Jin; Kim, Jiyoung; An, Jeung Hee; Kim, Wonwoo [Dept. of Radiation Oncology, Yonsei Univ. Medical College, Seoul (Korea, Republic of)

    2007-09-15

    In this study, we investigated the molecular factors determining the induction of apoptosis by radiation. Two murine tumors syngeneic to C3H/HeJ mice were used: an ovarian carcinoma OCa-I, and a hepatocarcinoma HCa-I. Both have wild type p53, but display distinctly different radiosensitivity in terms of specific growth delay (12.7 d in OCa-I and 0.3 d in HCa-I) and tumor cure dose 50% (52.6 Gy in OCa-I and >80 Gy in HCa-I). Eight-mm tumors on the thighs of mice were irradiated with 25 Gy and tumor samples were collected at regular time intervals after irradiation. The peak levels of apoptosis were 16.1{+-}0.6% in OCa-I and 0.2{+-}0.0% in HCa-I at 4 h after radiation, and this time point was used for subsequent proteomics analysis. Protein spots were identified by peptide mass fingerprinting with a focus on those related to apoptosis. In OCa-I tumors, radiation increased the expression of cytochrome c oxidase and Bcl2/adenovirus E1B-interacting 2 (Nip 2) protein higher than 3-fold. However in HCa-I, these two proteins showed no significant change. The results suggest that radiosensitivity in tumors with wild type p53 is regulated by a complex mechanism. Furthermore, these proteins could be molecular targets for a novel therapeutic strategy involving the regulation of radiosensitivity. (author)

  3. The evaluaton of prevalence rate of p53 antigen expression in cutaneous malignant melanoma and it′s relation to tumor thickness

    Directory of Open Access Journals (Sweden)

    Faghihi Gita

    2005-01-01

    Full Text Available P53 tumor suppressor gene mutation is one of the most common genetic alteration in human malignancies. This study was done to determine the prevalence of the P53 antigen expression by sex, age, type of melanoma, thickness of the lesion and site of the antigen expression either cytoplasmic or nuclear. Paraffin embeded block of 50 patients (45 primary and metastaticwith documented diagnosis of melanoma deparaffinized and immuno stained with DO-7 monoclonal antibody. The lesions were divided depending on the degree of the staining as follow: 1. no staining, 2. mild (less than 10%, 3. moderate (10%-50% staining, 4. severe (more than 50%. Fifty four percent of evaluated patients were female and 46% were male. Forty percent of lesions were graded as no staining, 36% of lesions showed mild staining, 14% moderate and 10% severe staining site of expression was excusively in the cytoplasm. There was no meaningful statistical deference between severity of staining and the age group, sex, type and thickness of melanoma. (p value was 0.532, 0.488, 0.626, 0.954 respectively.

  4. Down-regulation of Wild-type p53-induced Phosphatase 1 (Wip1) Plays a Critical Role in Regulating Several p53-dependent Functions in Premature Senescent Tumor Cells*

    Science.gov (United States)

    Crescenzi, Elvira; Raia, Zelinda; Pacifico, Francesco; Mellone, Stefano; Moscato, Fortunato; Palumbo, Giuseppe; Leonardi, Antonio

    2013-01-01

    Premature or drug-induced senescence is a major cellular response to chemotherapy in solid tumors. The senescent phenotype develops slowly and is associated with chronic DNA damage response. We found that expression of wild-type p53-induced phosphatase 1 (Wip1) is markedly down-regulated during persistent DNA damage and after drug release during the acquisition of the senescent phenotype in carcinoma cells. We demonstrate that down-regulation of Wip1 is required for maintenance of permanent G2 arrest. In fact, we show that forced expression of Wip1 in premature senescent tumor cells induces inappropriate re-initiation of mitosis, uncontrolled polyploid progression, and cell death by mitotic failure. Most of the effects of Wip1 may be attributed to its ability to dephosphorylate p53 at Ser15 and to inhibit DNA damage response. However, we also uncover a regulatory pathway whereby suppression of p53 Ser15 phosphorylation is associated with enhanced phosphorylation at Ser46, increased p53 protein levels, and induction of Noxa expression. On the whole, our data indicate that down-regulation of Wip1 expression during premature senescence plays a pivotal role in regulating several p53-dependent aspects of the senescent phenotype. PMID:23612976

  5. Tobacco, alcohol, and p53 overexpression in early colorectal neoplasia

    International Nuclear Information System (INIS)

    Terry, Mary Beth; Neugut, Alfred I; Mansukhani, Mahesh; Waye, Jerome; Harpaz, Noam; Hibshoosh, Hanina

    2003-01-01

    The p53 tumor suppressor gene is commonly mutated in colorectal cancer. While the effect of p53 mutations on colorectal cancer prognosis has been heavily studied, less is known about how epidemiologic risk factors relate to p53 status, particularly in early colorectal neoplasia prior to clinically invasive colorectal cancer (including adenomas, carcinoma in situ (CIS), and intramucosal carcinoma). We examined p53 status, as measured by protein overexpression, in 157 cases with early colorectal neoplasia selected from three New York City colonoscopy clinics. After collecting paraffin-embedded tissue blocks, immunohistochemistry was performed using an anti-p53 monoclonal mouse IgG 2 a [BP53-12-1] antibody. We analyzed whether p53 status was different for risk factors for colorectal neoplasia relative to a polyp-free control group (n = 508). p53 overexpression was found in 10.3%, 21.7%, and 34.9%, of adenomatous polyps, CIS, and intramucosal cases, respectively. Over 90% of the tumors with p53 overexpression were located in the distal colon and rectum. Heavy cigarette smoking (30+ years) was associated with cases not overexpressing p53 (OR = 1.8, 95% CI = 1.1–2.9) but not with those cases overexpressing p53 (OR = 1.0, 95% CI = 0.4–2.6). Heavy beer consumption (8+ bottles per week) was associated with cases overexpressing p53 (OR = 4.0, 95% CI = 1.3–12.0) but not with cases without p53 overexpression (OR = 1.6, 95% CI = 0.7–3.7). Our findings that p53 overexpression in early colorectal neoplasia may be positively associated with alcohol intake and inversely associated with cigarette smoking are consistent with those of several studies of p53 expression and invasive cancer, and suggest that there may be relationships of smoking and alcohol with p53 early in the adenoma to carcinoma sequence

  6. Nitric oxide prodrug JS-K inhibits ubiquitin E1 and kills tumor cells retaining wild-type p53.

    Science.gov (United States)

    Kitagaki, J; Yang, Y; Saavedra, J E; Colburn, N H; Keefer, L K; Perantoni, A O

    2009-01-29

    Nitric oxide (NO) is a major effector molecule in cancer prevention. A number of studies have shown that NO prodrug JS-K (O(2)-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate) induces apoptotic cell death in vitro and in vivo, indicating that it is a promising new therapeutic for cancer. However, the mechanism of its tumor-killing activity remains unclear. Ubiquitin plays an important role in the regulation of tumorigenesis and cell apoptosis. Our earlier report has shown that inactivation of the ubiquitin system through blocking E1 (ubiquitin-activating enzyme) activity preferentially induces apoptosis in p53-expressing transformed cells. As E1 has an active cysteine residue that could potentially interact with NO, we hypothesized that JS-K could inactivate E1 activity. E1 activity was evaluated by detecting ubiquitin-E1 conjugates through immunoblotting. JS-K strikingly inhibits the ubiquitin-E1 thioester formation in cells in a dose-dependent manner with an IC(50) of approximately 2 microM, whereas a JS-K analog that cannot release NO did not affect these levels in cells. Moreover, JS-K decreases total ubiquitylated proteins and increases p53 levels, which is mainly regulated by ubiquitin and proteasomal degradation. Furthermore, JS-K preferentially induces cell apoptosis in p53-expressing transformed cells. These findings indicate that JS-K inhibits E1 activity and kills transformed cells harboring wild-type p53.

  7. Identification of proteins that regulate radiation-induced apoptosis in murine tumors with wild type p53

    International Nuclear Information System (INIS)

    Seong, Jinsil; Oh, Hae Jin; Kim, Jiyoung; An, Jeung Hee; Kim, Wonwoo

    2007-01-01

    In this study, we investigated the molecular factors determining the induction of apoptosis by radiation. Two murine tumors syngeneic to C3H/HeJ mice were used: an ovarian carcinoma OCa-I, and a hepatocarcinoma HCa-I. Both have wild type p53, but display distinctly different radiosensitivity in terms of specific growth delay (12.7 d in OCa-I and 0.3 d in HCa-I) and tumor cure dose 50% (52.6 Gy in OCa-I and >80 Gy in HCa-I). Eight-mm tumors on the thighs of mice were irradiated with 25 Gy and tumor samples were collected at regular time intervals after irradiation. The peak levels of apoptosis were 16.1±0.6% in OCa-I and 0.2±0.0% in HCa-I at 4 h after radiation, and this time point was used for subsequent proteomics analysis. Protein spots were identified by peptide mass fingerprinting with a focus on those related to apoptosis. In OCa-I tumors, radiation increased the expression of cytochrome c oxidase and Bcl2/adenovirus E1B-interacting 2 (Nip 2) protein higher than 3-fold. However in HCa-I, these two proteins showed no significant change. The results suggest that radiosensitivity in tumors with wild type p53 is regulated by a complex mechanism. Furthermore, these proteins could be molecular targets for a novel therapeutic strategy involving the regulation of radiosensitivity. (author)

  8. Andrographolide induces degradation of mutant p53 via activation of Hsp70.

    Science.gov (United States)

    Sato, Hirofumi; Hiraki, Masatsugu; Namba, Takushi; Egawa, Noriyuki; Baba, Koichi; Tanaka, Tomokazu; Noshiro, Hirokazu

    2018-05-22

    The tumor suppressor gene p53 encodes a transcription factor that regulates various cellular functions, including DNA repair, apoptosis and cell cycle progression. Approximately half of all human cancers carry mutations in p53 that lead to loss of tumor suppressor function or gain of functions that promote the cancer phenotype. Thus, targeting mutant p53 as an anticancer therapy has attracted considerable attention. In the current study, a small-molecule screen identified andrographlide (ANDRO) as a mutant p53 suppressor. The effects of ANDRO, a small molecule isolated from the Chinese herb Andrographis paniculata, on tumor cells carrying wild-type or mutant p53 were examined. ANDRO suppressed expression of mutant p53, induced expression of the cyclin-dependent kinase inhibitor p21 and pro-apoptotic proteins genes, and inhibited the growth of cancer cells harboring mutant p53. ANDRO also induced expression of the heat-shock protein (Hsp70) and increased binding between Hsp70 and mutant p53 protein, thus promoting proteasomal degradation of p53. These results provide novel insights into the mechanisms regulating the function of mutant p53 and suggest that activation of Hsp70 may be a new strategy for the treatment of cancers harboring mutant p53.

  9. Phenotype specific analyses reveal distinct regulatory mechanism for chronically activated p53.

    Directory of Open Access Journals (Sweden)

    Kristina Kirschner

    2015-03-01

    Full Text Available The downstream functions of the DNA binding tumor suppressor p53 vary depending on the cellular context, and persistent p53 activation has recently been implicated in tumor suppression and senescence. However, genome-wide information about p53-target gene regulation has been derived mostly from acute genotoxic conditions. Using ChIP-seq and expression data, we have found distinct p53 binding profiles between acutely activated (through DNA damage and chronically activated (in senescent or pro-apoptotic conditions p53. Compared to the classical 'acute' p53 binding profile, 'chronic' p53 peaks were closely associated with CpG-islands. Furthermore, the chronic CpG-island binding of p53 conferred distinct expression patterns between senescent and pro-apoptotic conditions. Using the p53 targets seen in the chronic conditions together with external high-throughput datasets, we have built p53 networks that revealed extensive self-regulatory 'p53 hubs' where p53 and many p53 targets can physically interact with each other. Integrating these results with public clinical datasets identified the cancer-associated lipogenic enzyme, SCD, which we found to be directly repressed by p53 through the CpG-island promoter, providing a mechanistic link between p53 and the 'lipogenic phenotype', a hallmark of cancer. Our data reveal distinct phenotype associations of chronic p53 targets that underlie specific gene regulatory mechanisms.

  10. Battle Against Cancer: An Everlasting Saga of p53

    Directory of Open Access Journals (Sweden)

    Qian Hao

    2014-12-01

    Full Text Available Cancer is one of the most life-threatening diseases characterized by uncontrolled growth and spread of malignant cells. The tumor suppressor p53 is the master regulator of tumor cell growth and proliferation. In response to various stress signals, p53 can be activated and transcriptionally induces a myriad of target genes, including both protein-encoding and non-coding genes, controlling cell cycle progression, DNA repair, senescence, apoptosis, autophagy and metabolism of tumor cells. However, around 50% of human cancers harbor mutant p53 and, in the majority of the remaining cancers, p53 is inactivated through multiple mechanisms. Herein, we review the recent progress in understanding the molecular basis of p53 signaling, particularly the newly identified ribosomal stress—p53 pathway, and the development of chemotherapeutics via activating wild-type p53 or restoring mutant p53 functions in cancer. A full understanding of p53 regulation will aid the development of effective cancer treatments.

  11. Long term effect of curcumin in restoration of tumour suppressor p53 and phase-II antioxidant enzymes via activation of Nrf2 signalling and modulation of inflammation in prevention of cancer.

    Directory of Open Access Journals (Sweden)

    Laxmidhar Das

    Full Text Available Inhibition of carcinogenesis may be a consequence of attenuation of oxidative stress via activation of antioxidant defence system, restoration and stabilization of tumour suppressor proteins along with modulation of inflammatory mediators. Previously we have delineated significant role of curcumin during its long term effect in regulation of glycolytic pathway and angiogenesis, which in turn results in prevention of cancer via modulation of stress activated genes. Present study was designed to investigate long term effect of curcumin in regulation of Nrf2 mediated phase-II antioxidant enzymes, tumour suppressor p53 and inflammation under oxidative tumour microenvironment in liver of T-cell lymphoma bearing mice. Inhibition of Nrf2 signalling observed during lymphoma progression, resulted in down regulation of phase II antioxidant enzymes, p53 as well as activation of inflammatory signals. Curcumin potentiated significant increase in Nrf2 activation. It restored activity of phase-II antioxidant enzymes like GST, GR, NQO1, and tumour suppressor p53 level. In addition, curcumin modulated inflammation via upregulation of TGF-β and reciprocal regulation of iNOS and COX2. The study suggests that during long term effect, curcumin leads to prevention of cancer by inducing phase-II antioxidant enzymes via activation of Nrf2 signalling, restoration of tumour suppressor p53 and modulation of inflammatory mediators like iNOS and COX2 in liver of lymphoma bearing mice.

  12. The human ARF tumor suppressor senses blastema activity and suppresses epimorphic tissue regeneration

    Science.gov (United States)

    Hesse, Robert G; Kouklis, Gayle K; Ahituv, Nadav; Pomerantz, Jason H

    2015-01-01

    The control of proliferation and differentiation by tumor suppressor genes suggests that evolution of divergent tumor suppressor repertoires could influence species’ regenerative capacity. To directly test that premise, we humanized the zebrafish p53 pathway by introducing regulatory and coding sequences of the human tumor suppressor ARF into the zebrafish genome. ARF was dormant during development, in uninjured adult fins, and during wound healing, but was highly expressed in the blastema during epimorphic fin regeneration after amputation. Regenerative, but not developmental signals resulted in binding of zebrafish E2f to the human ARF promoter and activated conserved ARF-dependent Tp53 functions. The context-dependent activation of ARF did not affect growth and development but inhibited regeneration, an unexpected distinct tumor suppressor response to regenerative versus developmental environments. The antagonistic pleiotropic characteristics of ARF as both tumor and regeneration suppressor imply that inducing epimorphic regeneration clinically would require modulation of ARF –p53 axis activation. DOI: http://dx.doi.org/10.7554/eLife.07702.001 PMID:26575287

  13. The effect of intense intermittent training with and without taking vitamin E on mRNA expression of p53/PTEN tumor suppressing genes in prostate glands of male rats

    Directory of Open Access Journals (Sweden)

    Mohammad Esmaeil Afzalpour

    2016-11-01

    Full Text Available Physical activity and diet are the most important modifiable determinants of cancer risk. The objective of this study was to examine the effect of intense intermittent training with and without taking vitamin E on expression of p53 and PTEN tumor suppressing genes in the prostate gland of male rats. For this purpose, 50 Sprague-Dawley male rats were randomly assigned into 5 groups: [1] control (CON, n = 10, [2] sham (S, n = 10, [3] intense intermittent training (IIT, n = 10, [4] intense intermittent training + vitamin E (IIT + VE, n = 10, [5] vitamin E (VE, n = 10. Protocol of this study was implemented for 6 days per week for 6 weeks, with observing the overload principle on the motorized treadmill. After implementing training protocol, expression rate of p53 and PTEN genes reduced significantly (p<0.000, p<0.031, respectively. Taking vitamin E with intermittent training caused significant reduction in p53 expression (p<0.013, while it caused significant increase in expression of PTEN (p<0.035. These results showed that intense intermittent training reduces expression of p53 and PTEN tumor suppressing genes and taking supplementation vitamin E along with this type of training could cause different effects in expression of these tumor suppressor genes.

  14. Characterization of highly frequent epitope-specific CD45RA+/CCR7+/- T lymphocyte responses against p53-binding domains of the human polyomavirus BK large tumor antigen in HLA-A*0201+ BKV-seropositive donors

    Directory of Open Access Journals (Sweden)

    Zajac Paul

    2006-11-01

    Full Text Available Abstract Human polyomavirus BK (BKV has been implicated in oncogenic transformation. Its ability to replicate is determined by the binding of its large tumor antigen (LTag to products of tumor-suppressor genes regulating cell cycle, as specifically p53. We investigated CD8+ T immune responses to BKV LTag portions involved in p53 binding in HLA-A*0201+ BKV LTag experienced individuals. Peptides selected from either p53-binding region (LTag351–450 and LTag533–626 by current algorithms and capacity to bind HLA-A*0201 molecule were used to stimulate CD8+ T responses, as assessed by IFN-γ gene expression ex vivo and detected by cytotoxicity assays following in vitro culture. We observed epitope-specific immune responses in all HLA-A*0201+ BKV LTag experienced individuals tested. At least one epitope, LTag579–587; LLLIWFRPV, was naturally processed in non professional antigen presenting cells and induced cytotoxic responses with CTL precursor frequencies in the order of 1/20'000. Antigen specific CD8+ T cells were only detectable in the CD45RA+ subset, in both CCR7+ and CCR7- subpopulations. These data indicate that widespread cellular immune responses against epitopes within BKV LTag-p53 binding regions exist and question their roles in immunosurveillance against tumors possibly associated with BKV infection.

  15. Interactions of Chromatin Context, Binding Site Sequence Content, and Sequence Evolution in Stress-Induced p53 Occupancy and Transactivation

    OpenAIRE

    Su, Dan; Wang, Xuting; Campbell, Michelle R.; Song, Lingyun; Safi, Alexias; Crawford, Gregory E.; Bell, Douglas A.

    2015-01-01

    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, ...

  16. 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.

  17. 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.

  18. Sublethal dose of irradiation enhances invasion of malignant glioma cells through p53-MMP 2 pathway in U87MG mouse brain tumor model

    International Nuclear Information System (INIS)

    Pei, Jian; Park, In-Ho; Ryu, Hyang-Hwa; Li, Song-Yuan; Li, Chun-Hao; Lim, Sa-Hoe; Wen, Min; Jang, Woo-Youl; Jung, Shin

    2015-01-01

    Glioblastoma is a highly lethal neoplasm that frequently recurs locally after radiotherapy, and most of these recurrences originate from near the irradiated target field. In the present study, we identified the effects of radiation on glioma invasion and p53, TIMP-2, and MMP-2 expression through in vitro and in vivo experiments. The U87MG (wt p53) and U251 (mt p53) human malignant glioma cell lines were prepared, and the U2OS (wt 53) and Saos2 (del p53) osteosarcoma cell lines were used as p53 positive and negative controls. The four cell lines and p53 knock-downed U87MG cells received radiation (2–6 Gy) and were analyzed for expression of p53 and TIMP-2 by Western blot, and MMP-2 activity was detected by zymography. In addition, the effects of irradiation on directional invasion of malignant glioma were evaluated by implanting nude mice with bioluminescent u87-Fluc in vivo followed by MMP-2, p53, and TIMP-2 immunohisto-chemistry and in situ zymography. MMP-2 activity and p53 expression increased in proportional to the radiation dose in cell lines with wt p53, but not in the cell lines with del or mt p53. TIMP-2 expression did not increase in U87MG cells. MMP-2 activity decreased in p53 knock-downed U87MG cells but increased in the control group. Furthermore, radiation enhanced MMP-2 activity and increased tumor margin invasiveness in vivo. Tumor cells invaded by radiation overexpressed MMP-2 and p53 and revealed high gelatinolytic activity compared with those of non-radiated tumor cells. Radiation-induced upregulation of p53 modulated MMP-2 activity, and the imbalance between MMP-2 and TIMP-2 may have an important role in glioblastoma invasion by degrading the extracellular matrix. Bioluminescent “U87-Fluc”was useful for observing tumor formation without sacrifice after implanting tumor cells in the mouse brain. These findings suggest that the radiotherapy involved field for malignant glioma needs to be reconsidered, and that future trials should investigate

  19. The Hunger Games: p53 regulates metabolism upon serine starvation.

    Science.gov (United States)

    Tavana, Omid; Gu, Wei

    2013-02-05

    Cancer cells reprogram their metabolism to support a high proliferative rate. A new study shows that, upon serine starvation, the tumor suppressor p53 activates p21 to shift metabolic flux from purine biosynthesis to glutathione production, which enhances cellular proliferation and viability by combating ROS (Maddocks et al., 2013). Copyright © 2013 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2007-04-18

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

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

    Czech Academy of Sciences Publication Activity Database

    Brázda, Václav; Čechová, Jana; Battistin, M.; Coufal, Jan; Jagelská, Eva; Raimondi, I.; Inga, A.

    2017-01-01

    Roč. 483, č. 1 (2017), s. 516-521 ISSN 0006-291X R&D Projects: GA ČR GA15-21855S Institutional support: RVO:68081707 Keywords : tumor-suppressor p53 * cruciform structures * dna-conformation Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 2.466, year: 2016

  2. Development of Spontaneous Mammary Tumors in BALB/c-p53+-Mice: Detection of Early Genetic Alterations and the Mapping of BALB/c Susceptibility Genes

    National Research Council Canada - National Science Library

    Blackburn, Anneke

    2002-01-01

    The TP53 tumor suppressor gene is defective in the majority of sporadic breast cancers, and breast cancer is the most frequent tumor type in women with Li-Fraumeni syndrome who inherit germline mutations in TP53...

  3. Development of Spontaneous Mammary Tumors in BALB/c-p53+/-Mice: Detection of Early Genetic Alterations and the Mapping of BALB/c Susceptibility Genes

    National Research Council Canada - National Science Library

    Smith, Sallie

    2004-01-01

    The TP53 tumor suppressor gene is defective in the majority of sporadic breast cancers, and breast cancer is the most frequent tumor type in women with Li-Fraumeni syndrome and bear germline mutations in TP53...

  4. Molecular dynamics simulation of S100B protein to explore ligand blockage of the interaction with p53 protein

    Science.gov (United States)

    Zhou, Zhigang; Li, Yumin

    2009-10-01

    As a tumor suppressor, p53 plays an important role in cancer suppression. The biological function of p53 as a tumor suppressor is disabled when it binds to S100B. Developing the ligands to block the S100B-p53 interaction has been proposed as one of the most important approaches to the development of anti-cancer agents. We screened a small compound library against the binding interface of S100B and p53 to identify potential compounds to interfere with the interaction. The ligand-binding effect on the S100B-p53 interaction was explored by molecular dynamics at the atomic level. The results show that the ligand bound between S100B and p53 propels the two proteins apart by about 2 Å compared to the unligated S100B-p53 complex. The binding affinity of S100B and p53 decreases by 8.5-14.6 kcal/mol after a ligand binds to the interface from the original unligated state of the S100B-p53 complex. Ligand-binding interferes with the interaction of S100B and p53. Such interference could impact the association of S100B and p53, which would free more p53 protein from the pairing with S100B and restore the biological function of p53 as a tumor suppressor. The analysis of the binding mode and ligand structural features would facilitate our effort to identify and design ligands to block S100B-p53 interaction effectively. The results from the work suggest that developing ligands targeting the interface of S100B and p53 could be a promising approach to recover the normal function of p53 as a tumor suppressor.

  5. Down-Regulation of p53 by Double-Stranded RNA Modulates the Antiviral Response

    OpenAIRE

    Marques, Joao T.; Rebouillat, Dominique; Ramana, Chilakamarti V.; Murakami, Junko; Hill, Jason E.; Gudkov, Andrei; Silverman, Robert H.; Stark, George R.; Williams, Bryan R. G.

    2005-01-01

    p53 has been well characterized as a tumor suppressor gene, but its role in antiviral defense remains unclear. A recent report has demonstrated that p53 can be induced by interferons and is activated after vesicular stomatitis virus (VSV) infection. We observed that different nononcogenic viruses, including encephalomyocarditis virus (EMCV) and human parainfluenza virus type 3 (HPIV3), induced down-regulation of p53 in infected cells. Double-stranded RNA (dsRNA) and a mutant vaccinia virus la...

  6. The tumor suppressor gene Trp53 protects the mouse lens against posterior subcapsular cataracts and the BMP receptor Acvr1 acts as a tumor suppressor in the lens

    Directory of Open Access Journals (Sweden)

    Luke A. Wiley

    2011-07-01

    We previously found that lenses lacking the Acvr1 gene, which encodes a bone morphogenetic protein (BMP receptor, had abnormal proliferation and cell death in epithelial and cortical fiber cells. We tested whether the tumor suppressor protein p53 (encoded by Trp53 affected this phenotype. Acvr1 conditional knockout (Acvr1CKO mouse fiber cells had increased numbers of nuclei that stained for p53 phosphorylated on serine 15, an indicator of p53 stabilization and activation. Deletion of Trp53 rescued the Acvr1CKO cell death phenotype in embryos and reduced Acvr1-dependent apoptosis in postnatal lenses. However, deletion of Trp53 alone increased the number of fiber cells that failed to withdraw from the cell cycle. Trp53CKO and Acvr1;Trp53DCKO (double conditional knockout, but not Acvr1CKO, lenses developed abnormal collections of cells at the posterior of the lens that resembled posterior subcapsular cataracts. Cells from human posterior subcapsular cataracts had morphological and molecular characteristics similar to the cells at the posterior of mouse lenses lacking Trp53. In Trp53CKO lenses, cells in the posterior plaques did not proliferate but, in Acvr1;Trp53DCKO lenses, many cells in the posterior plaques continued to proliferate, eventually forming vascularized tumor-like masses at the posterior of the lens. We conclude that p53 protects the lens against posterior subcapsular cataract formation by suppressing the proliferation of fiber cells and promoting the death of any fiber cells that enter the cell cycle. Acvr1 acts as a tumor suppressor in the lens. Enhancing p53 function in the lens could contribute to the prevention of steroid- and radiation-induced posterior subcapsular cataracts.

  7. Estrogen receptor positive breast tumors resist chemotherapy by the overexpression of P53 in Cancer Stem Cells

    Directory of Open Access Journals (Sweden)

    Fatma Ashour

    2018-06-01

    Full Text Available Background and Objectives: Breast cancer (BC is classified according to estrogen receptor (ER status into ER+ and ER− tumors. ER+ tumors have a worse response to chemotherapy compared to ER− tumors. BCL-2, TP53, BAX and NF-ΚB are involved in drug resistance in the ER+ tumors. Recently it was shown that Cancer Stem Cells (CSCs play an important role in drug resistance. In this study we tested the hypothesis that CSCs of the ER+ tumors resist drug through the overexpression of BCL-2, TP53, BAX and NF-ΚB. Methods: CSCs were isolated by anoikis resistance assay from MCF7 (ER+ and MDA-MB-231 (ER− cell lines. Isolated CSCs were treated with doxorubicin (DOX and the mRNA expression levels of BCL-2, TP53, BAX and NFKB were investigated by quantitative real time PCR (qPCR with and without treatment. Results: BCL-2, BAX and NF-ΚB showed decreased expression in MCF7 bulk cancer cells after DOX treatment whereas only BCL-2 and BAX showed decreased expression in MDA-MB-231 bulk cancer cells. Interestingly TP53 was the only gene showed a considerable increase in its expression in CSCs of the ER+ MCF7 cell line compared to bulk cancer cells. Moreover, TP53 was the only gene showing exceptionally higher level of expression in MCF7-CSCs compared to MDA-MB-231-CSCs. Conclusion: Our results suggest that CSCs in the ER+ cells escape the effect of DOX treatment by the elevation of p53 expression. Keywords: Breast cancer, Cancer Stem Cells, Drug resistance, Estrogen receptors

  8. Functional promoter upstream p53 regulatory sequence of IGFBP3 that is silenced by tumor specific methylation

    International Nuclear Information System (INIS)

    Hanafusa, Tadashi; Shinji, Toshiyuki; Shiraha, Hidenori; Nouso, Kazuhiro; Iwasaki, Yoshiaki; Yumoto, Eichiro; Ono, Toshiro; Koide, Norio

    2005-01-01

    Insulin-like growth factor binding protein (IGFBP)-3 functions as a carrier of insulin-like growth factors (IGFs) in circulation and a mediator of the growth suppression signal in cells. There are two reported p53 regulatory regions in the IGFBP3 gene; one upstream of the promoter and one intronic. We previously reported a hot spot of promoter hypermethylation of IGFBP-3 in human hepatocellular carcinomas and derivative cell lines. As the hot spot locates at the putative upstream p53 consensus sequences, these p53 consensus sequences are really functional is a question to be answered. In this study, we examined the p53 consensus sequences upstream of the IGFBP-3 promoter for the p53 induced expression of IGFBP-3. Deletion, mutagenesis, and methylation constructs of IGFBP-3 promoter were assessed in the human hepatoblastoma cell line HepG2 for promoter activity. Deletions and mutations of these sequences completely abolished the expression of IGFBP-3 in the presence of p53 overexpression. In vitro methylation of these p53 consensus sequences also suppressed IGFBP-3 expression. In contrast, the expression of IGFBP-3 was not affected in the absence of p53 overexpression. Further, we observed by electrophoresis mobility shift assay that p53 binding to the promoter region was diminished when methylated. From these observations, we conclude that four out of eleven p53 consensus sequences upstream of the IGFBP-3 promoter are essential for the p53 induced expression of IGFBP-3, and hypermethylation of these sequences selectively suppresses p53 induced IGFBP-3 expression in HepG2 cells

  9. Avian Reovirus Protein p17 Functions as a Nucleoporin Tpr Suppressor Leading to Activation of p53, p21 and PTEN and Inactivation of PI3K/AKT/mTOR and ERK Signaling Pathways.

    Directory of Open Access Journals (Sweden)

    Wei-Ru Huang

    Full Text Available Avian reovirus (ARV protein p17 has been shown to regulate cell cycle and autophagy by activation of p53/PTEN pathway; nevertheless, it is still unclear how p53 and PTEN are activated by p17. Here, we report for the first time that p17 functions as a nucleoporin Tpr suppressor that leads to p53 nuclear accumulation and consequently activates p53, p21, and PTEN. The nuclear localization signal (119IAAKRGRQLD128 of p17 has been identified for Tpr binding. This study has shown that Tpr suppression occurs by p17 interacting with Tpr and by reducing the transcription level of Tpr, which together inhibit Tpr function. In addition to upregulation of PTEN by activation of p53 pathway, this study also suggests that ARV protein p17 acts as a positive regulator of PTEN. ARV p17 stabilizes PTEN by stimulating phosphorylation of cytoplasmic PTEN and by elevating Rak-PTEN association to prevent it from E3 ligase NEDD4-1 targeting. To activate PTEN, p17 is able to promote β-arrestin-mediated PTEN translocation from the cytoplasm to the plasma membrane via a Rock-1-dependent manner. The accumulation of p53 in the nucleus induces the PTEN- and p21-mediated downregulation of cyclin D1 and CDK4. Furthermore, Tpr and CDK4 knockdown increased virus production in contrast to depletion of p53, PTEN, and LC3 reducing virus yield. Taken together, our data suggest that p17-mediated Tpr suppression positively regulates p53, PTEN, and p21 and negatively regulates PI3K/AKT/mTOR and ERK signaling pathways, both of which are beneficial for virus replication.

  10. The role of p53 molecule in radiation and hyperthermic therapies

    International Nuclear Information System (INIS)

    Yasumoto, Jun-ichi; Takahashi, Akihisa; Ohnishi, Ken; Ohnishi, Takeo

    2003-01-01

    In recent years, cancer-related genes have been analyzed at the molecular level as predictive indicators for cancer therapy. Among those genes, the tumor suppressor gene p53 is worthy of notice in cancer therapy, because the p53 molecule prevents the malignant degeneration of non-cancer cells by regulating cell-cycle arrest, apoptosis, and DNA repair. An abnormality of the p53 gene introduces a genetic instability and increases the incidence of carcinogenesis and teratogenesis. Therefore, p53 is called a guardian of the genome. Mutations of p53 are observed at a high frequency in human tumors, and are recognized in about half of all malignant tumors in human head and neck cancers. We previously reported that radio- and heat-sensitivities of human cultured tongue squamous cell carcinoma cells are p53-dependent, and are closely correlated with the induction of apoptosis. In a human cell culture system, the interactive hyperthermic enhancement of radiosensitivity was observed in wild-type p53 cells, but not in mutated p53 cells. In a transplanted tumor system, the combination therapies of radiation and hyperthermia induced efficient tumor growth depression and apoptosis in the wild-type p53 tumors. In this review, we discuss the p53 activation signaling pathways through the modification of p53 molecules, such as phosphorylation after radiation and hyperthermia treatments. (author)

  11. Friend or Foe: MicroRNAs in the p53 network.

    Science.gov (United States)

    Luo, Zhenghua; Cui, Ri; Tili, Esmerina; Croce, Carlo

    2018-04-10

    The critical tumor suppressor gene TP53 is either lost or mutated in more than half of human cancers. As an important transcriptional regulator, p53 modulates the expression of many microRNAs. While wild-type p53 uses microRNAs to suppress cancer development, microRNAs that are activated by gain-of-function mutant p53 confer oncogenic properties. On the other hand, the expression of p53 is tightly controlled by a fine-tune machinery including microRNAs. MicroRNAs can target the TP53 gene directly or other factors in the p53 network so that expression and function of either the wild-type or the mutant forms of p53 is downregulated. Therefore, depending on the wild-type or mutant p53 context, microRNAs contribute substantially to suppress or exacerbate tumor development. Copyright © 2018. Published by Elsevier B.V.

  12. DRAGO (KIAA0247), a new DNA damage-responsive, p53-inducible gene that cooperates with p53 as oncosuppressor. [Corrected].

    Science.gov (United States)

    Polato, Federica; Rusconi, Paolo; Zangrossi, Stefano; Morelli, Federica; Boeri, Mattia; Musi, Alberto; Marchini, Sergio; Castiglioni, Vittoria; Scanziani, Eugenio; Torri, Valter; Broggini, Massimo

    2014-04-01

    p53 influences genomic stability, apoptosis, autophagy, response to stress, and DNA damage. New p53-target genes could elucidate mechanisms through which p53 controls cell integrity and response to damage. DRAGO (drug-activated gene overexpressed, KIAA0247) was characterized by bioinformatics methods as well as by real-time polymerase chain reaction, chromatin immunoprecipitation and luciferase assays, time-lapse microscopy, and cell viability assays. Transgenic mice (94 p53(-/-) and 107 p53(+/-) mice on a C57BL/6J background) were used to assess DRAGO activity in vivo. Survival analyses were performed using Kaplan-Meier curves and the Mantel-Haenszel test. All statistical tests were two-sided. We identified DRAGO as a new p53-responsive gene induced upon treatment with DNA-damaging agents. DRAGO is highly conserved, and its ectopic overexpression resulted in growth suppression and cell death. DRAGO(-/-) mice are viable without macroscopic alterations. However, in p53(-/-) or p53(+/-) mice, the deletion of both DRAGO alleles statistically significantly accelerated tumor development and shortened lifespan compared with p53(-/-) or p53(+/-) mice bearing wild-type DRAGO alleles (p53(-/-), DRAGO(-/-) mice: hazard ratio [HR] = 3.25, 95% confidence interval [CI] = 1.7 to 6.1, P < .001; p53(+/-), DRAGO(-/-) mice: HR = 2.35, 95% CI = 1.3 to 4.0, P < .001; both groups compared with DRAGO(+/+) counterparts). DRAGO mRNA levels were statistically significantly reduced in advanced-stage, compared with early-stage, ovarian tumors, but no mutations were found in several human tumors. We show that DRAGO expression is regulated both at transcriptional-through p53 (and p73) and methylation-dependent control-and post-transcriptional levels by miRNAs. DRAGO represents a new p53-dependent gene highly regulated in human cells and whose expression cooperates with p53 in tumor suppressor functions.

  13. TRIM65 negatively regulates p53 through ubiquitination

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang [Department of Respiration, The First Hospital of Jilin University, Changchun 130021 (China); Ma, Chengyuan [Department of Neurosurgery, The First Hospital of Jilin University, Changchun 130021 (China); Zhou, Tong [Department of Endocrinology, The First Hospital of Jilin University, Changchun 130021 (China); Liu, Ying [Department of Respiration, The First Hospital of Jilin University, Changchun 130021 (China); Sun, Luyao [Department of Infectious Diseases, The First Hospital of Jilin University, Changchun 130021 (China); Yu, Zhenxiang, E-mail: zhenxiangyu2015@gmail.com [Department of Respiration, The First Hospital of Jilin University, Changchun 130021 (China)

    2016-04-22

    Tripartite-motif protein family member 65 (TRIM65) is an important protein involved in white matter lesion. However, the role of TRIM65 in human cancer remains less understood. Through the Cancer Genome Atlas (TCGA) gene alteration database, we found that TRIM65 is upregulated in a significant portion of non-small cell lung carcinoma (NSCLC) patients. Our cell growth assay revealed that TRIM65 overexpression promotes cell proliferation, while knockdown of TRIM65 displays opposite effect. Mechanistically, TRIM65 binds to p53, one of the most critical tumor suppressors, and serves as an E3 ligase toward p53. Consequently, TRIM65 inactivates p53 through facilitating p53 poly-ubiquitination and proteasome-mediated degradation. Notably, chemotherapeutic reagent cisplatin induction of p53 is markedly attenuated in response to ectopic expression of TRIM65. Cell growth inhibition by TRIM65 knockdown is more significant in p53 positive H460 than p53 negative H1299 cells, and knockdown of p53 in H460 cells also shows compromised cell growth inhibition by TRIM65 knockdown, indicating that p53 is required, at least in part, for TRIM65 function. Our findings demonstrate TRIM65 as a potential oncogenic protein, highly likely through p53 inactivation, and provide insight into development of novel approaches targeting TRIM65 for NSCLC treatment, and also overcoming chemotherapy resistance. - Highlights: • TRIM65 expression is elevated in NSCLC. • TRIM65 inactivates p53 through mediating p53 ubiquitination and degradation. • TRIM65 attenuates the response of NSCLC cells to cisplatin.

  14. An adaptive molecular timer in p53-meidated cell fate decision

    Science.gov (United States)

    Zhang, Xiao-Peng; Wang, Ping; Liu, Feng; Wang, Wei

    The tumor suppressor p53 decides cellular outcomes in the DNA damage response. It is intriguing to explore the link between p53 dynamics and cell fates. We developed a theoretical model of p53 signaling network to clarify the mechanism of cell fate decision mediated by its dynamics. We found that the interplay between p53-Mdm2 negative feedback loop and p53-PTEN-Mdm2 positive feedback loop shapes p53 dynamics. Depending on the intensity of DNA damage, p53 shows three modes of dynamics: persistent pulses, two-phase dynamics with pulses followed by sustained high levels and straightforward high levels. Especially, p53 shows two-phase dynamics upon moderated damage and the required number of p53 pulses before apoptosis induction decreases with increasing DNA damage. Our results suggested there exists an adaptive molecular timer that determines whether and when the apoptosis switch should be triggered. We clarified the mechanism behind the switching of p53 dynamical modes by bifurcation analysis. Moreover, we reproduced the experimental results that drug additions alter p53 pulses to sustained p53 activation and leads to senescence. Our work may advance the understanding the significance of p53 dynamics in tumor suppression. This work was supported by National Natural Science Foundation of China (Nos. 11175084, 11204126 and 31361163003).

  15. Abundant immunohistochemical expression of dopamine D{sub 2} receptor and p53 protein in meningiomas: follow-up, relation to gender, age, tumor grade, and recurrence

    Energy Technology Data Exchange (ETDEWEB)

    Trott, G.; Pereira-Lima, J.F.S.; Leães, C.G.S. [Programa de Graduação em Patologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS (Brazil); Centro de Neuroendocrinologia, Complexo Hospitalar Santa Casa de Porto Alegre, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS (Brazil); Ferreira, N.P. [Centro de Neuroendocrinologia, Complexo Hospitalar Santa Casa de Porto Alegre, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS (Brazil); Barbosa-Coutinho, L.M. [Programa de Graduação em Patologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS (Brazil); Oliveira, M.C. [Programa de Graduação em Patologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS (Brazil); Centro de Neuroendocrinologia, Complexo Hospitalar Santa Casa de Porto Alegre, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS (Brazil)

    2015-03-03

    Meningiomas are common, usually benign tumors, with a high postoperative recurrence rate. However, the genesis and development of these tumors remain controversial. We aimed to investigate the presence and implications of a mutated p53 protein and dopamine D{sub 2} receptor in a representative series of meningiomas and to correlate these findings with age, gender, tumor grade, and recurrence. Tumor tissue samples of 157 patients diagnosed with meningioma (37 males and 120 females, mean age 53.6±14.3 years) who underwent surgical resection between 2003 and 2012 at our institution were immunohistochemically evaluated for the presence of p53 protein and dopamine D{sub 2} receptor and were followed-up to analyze tumor recurrence or regrowth. Tumors were classified as grades I (n=141, 89.8%), II (n=13, 8.3%), or grade III (n=3, 1.9%). Dopamine D{sub 2} receptor and p53 protein expression were positive in 93.6% and 49.7% of the cases, respectively. Neither of the markers showed significant expression differences among different tumor grades or recurrence or regrowth statuses. Our findings highlight the potential role of p53 protein in meningioma development and/or progression. The high positivity of dopamine D{sub 2} receptor observed in this study warrants further investigation of the therapeutic potential of dopamine agonists in the evolution of meningiomas.

  16. Abundant immunohistochemical expression of dopamine D2 receptor and p53 protein in meningiomas: follow-up, relation to gender, age, tumor grade, and recurrence

    International Nuclear Information System (INIS)

    Trott, G.; Pereira-Lima, J.F.S.; Leães, C.G.S.; Ferreira, N.P.; Barbosa-Coutinho, L.M.; Oliveira, M.C.

    2015-01-01

    Meningiomas are common, usually benign tumors, with a high postoperative recurrence rate. However, the genesis and development of these tumors remain controversial. We aimed to investigate the presence and implications of a mutated p53 protein and dopamine D 2 receptor in a representative series of meningiomas and to correlate these findings with age, gender, tumor grade, and recurrence. Tumor tissue samples of 157 patients diagnosed with meningioma (37 males and 120 females, mean age 53.6±14.3 years) who underwent surgical resection between 2003 and 2012 at our institution were immunohistochemically evaluated for the presence of p53 protein and dopamine D 2 receptor and were followed-up to analyze tumor recurrence or regrowth. Tumors were classified as grades I (n=141, 89.8%), II (n=13, 8.3%), or grade III (n=3, 1.9%). Dopamine D 2 receptor and p53 protein expression were positive in 93.6% and 49.7% of the cases, respectively. Neither of the markers showed significant expression differences among different tumor grades or recurrence or regrowth statuses. Our findings highlight the potential role of p53 protein in meningioma development and/or progression. The high positivity of dopamine D 2 receptor observed in this study warrants further investigation of the therapeutic potential of dopamine agonists in the evolution of meningiomas

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

    Energy Technology Data Exchange (ETDEWEB)

    Cappadone, C., E-mail: concettina.cappadone@unibo.it [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Stefanelli, C. [Department for Life Quality Studies, University of Bologna, Rimini Campus, Rimini (Italy); Malucelli, E. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Zini, M. [Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna (Italy); Onofrillo, C. [Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna (Italy); Locatelli, A.; Rambaldi, M.; Sargenti, A. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Merolle, L. [ELETTRA–Sincrotrone Trieste S.C.p.A., Trieste (Italy); Farruggia, G. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); National Institute of Biostructures and Biosystems, Roma (Italy); Graziadio, A. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Montanaro, L. [Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna (Italy); Iotti, S. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); National Institute of Biostructures and Biosystems, Roma (Italy)

    2015-11-13

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  19. Exploring a minimal two-component p53 model

    International Nuclear Information System (INIS)

    Sun, Tingzhe; Zhu, Feng; Shen, Pingping; Yuan, Ruoshi; Xu, Wei

    2010-01-01

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

  20. The genetic alteration of p53 in esophageal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jae Il; Baik, Hee Jong; Kim, Chang Min; Kim, Mi Hee [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1996-01-01

    Genetic alterations in the p53 gene have been detected in various human malignancies, and its alterations inactive the function of p53 as a tumor suppressor. Point mutation and gene deletion are the main mechanisms of p53 inactivation. To determine the incidence of genetic alteration of p53 and their clinical implications in Korean patients of esophageal cancer, we investigated p53 alterations in 26 esophageal cancer tissues paired with its normal tissue by Southern blot analysis, PCR-SSCP, and direct sequencing. Allelic loss of chromosome 17p occurred in 12 out of 21 informative cases(57%) by Southern blot analysis, and 16 cases showed mobility shift in PCR-SSCP, so overall incidence of p53 gene alterations was 77%(20/26). The mutations detected was randomly dispersed over exon4-8 and was frequently G-T transversion and C:T transitions. Three identical mutations were clustered at codon 213 suggested the same etiologic agents in this cases. The p53 gene alterations play a significant role in the development of esophageal cancers, however, no relationship between p53 mutation and clinical data was detected so far. 9 refs. (Author).

  1. Reactivating p53 and Inducing Tumor Apoptosis (RITA Enhances the Response of RITA-Sensitive Colorectal Cancer Cells to Chemotherapeutic Agents 5-Fluorouracil and Oxaliplatin

    Directory of Open Access Journals (Sweden)

    Armin Wiegering

    2017-04-01

    Full Text Available Colorectal carcinoma (CRC is the most common cancer of the gastrointestinal tract with frequently dysregulated intracellular signaling pathways, including p53 signaling. The mainstay of chemotherapy treatment of CRC is 5-fluorouracil (5FU and oxaliplatin. The two anticancer drugs mediate their therapeutic effect via DNA damage-triggered signaling. The small molecule reactivating p53 and inducing tumor apoptosis (RITA is described as an activator of wild-type and reactivator of mutant p53 function, resulting in elevated levels of p53 protein, cell growth arrest, and cell death. Additionally, it has been shown that RITA can induce DNA damage signaling. It is expected that the therapeutic benefits of 5FU and oxaliplatin can be increased by enhancing DNA damage signaling pathways. Therefore, we highlighted the antiproliferative response of RITA alone and in combination with 5FU or oxaliplatin in human CRC cells. A panel of long-term established CRC cell lines (n = 9 including p53 wild-type, p53 mutant, and p53 null and primary patient-derived, low-passage cell lines (n = 5 with different p53 protein status were used for this study. A substantial number of CRC cells with pronounced sensitivity to RITA (IC50< 3.0 μmol/l were identified within established (4/9 and primary patient-derived (2/5 CRC cell lines harboring wild-type or mutant p53 protein. Sensitivity to RITA appeared independent of p53 status and was associated with an increase in antiproliferative response to 5FU and oxaliplatin, a transcriptional increase of p53 targets p21 and NOXA, and a decrease in MYC mRNA. The effect of RITA as an inducer of DNA damage was shown by a strong elevation of phosphorylated histone variant H2A.X, which was restricted to RITA-sensitive cells. Our data underline the primary effect of RITA, inducing DNA damage, and demonstrate the differential antiproliferative effect of RITA to CRC cells independent of p53 protein status. We found a substantial number

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

    International Nuclear Information System (INIS)

    Morris, Suzanne M.; Akerman, Gregory S.; Desai, Varsha G.; Tsai, Chen-an; Tolleson, William H.; Melchior, William B.; Lin, Chien-Ju; Fuscoe, James C.; Casciano, Daniel A.; Chen, James J.

    2008-01-01

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

  3. Knockout and transgenic mice of Trp53: what have we learned about p53 in breast cancer?

    International Nuclear Information System (INIS)

    Blackburn, Anneke C; Jerry, D Joseph

    2002-01-01

    The human p53 tumor suppressor gene TP53 is mutated at a high frequency in sporadic breast cancer, and Li-Fraumeni syndrome patients who carry germline mutations in one TP53 allele have a high incidence of breast cancer. In the 10 years since the first knockout of the mouse p53 tumor suppressor gene (designated Trp53) was published, much has been learned about the contribution of p53 to biology and tumor suppression in the breast through the use of p53 transgenic and knockout mice. The original mice deficient in p53 showed no mammary gland phenotype. However, studies using BALB/c-Trp53-deficient mice have demonstrated a delayed involution phenotype and a mammary tumor phenotype. Together with other studies of mutant p53 transgenes and p53 bitransgenics, a greater understanding has been gained of the role of p53 in involution, of the regulation of p53 activity by hormones, of the effect of mouse strain and modifier genes on tumor phenotype, and of the cooperation between p53 and other oncogenic pathways, chemical carcinogens and hormonal stimulation in mammary tumorigenesis. Both p53 transgenic and knockout mice are important in vivo tools for understanding breast cancer, and are yet to be exploited for developing therapeutic strategies in breast cancer

  4. Using a preclinical mouse model of high-grade astrocytoma to optimize p53 restoration therapy.

    Science.gov (United States)

    Shchors, Ksenya; Persson, Anders I; Rostker, Fanya; Tihan, Tarik; Lyubynska, Natalya; Li, Nan; Swigart, Lamorna Brown; Berger, Mitchel S; Hanahan, Douglas; Weiss, William A; Evan, Gerard I

    2013-04-16

    Based on clinical presentation, glioblastoma (GBM) is stratified into primary and secondary types. The protein 53 (p53) pathway is functionally incapacitated in most GBMs by distinctive type-specific mechanisms. To model human gliomagenesis, we used a GFAP-HRas(V12) mouse model crossed into the p53ER(TAM) background, such that either one or both copies of endogenous p53 is replaced by a conditional p53ER(TAM) allele. The p53ER(TAM) protein can be toggled reversibly in vivo between wild-type and inactive conformations by administration or withdrawal of 4-hydroxytamoxifen (4-OHT), respectively. Surprisingly, gliomas that develop in GFAP-HRas(V12);p53(+/KI) mice abrogate the p53 pathway by mutating p19(ARF)/MDM2 while retaining wild-type p53 allele. Consequently, such tumors are unaffected by restoration of their p53ER(TAM) allele. By contrast, gliomas arising in GFAP-HRas(V12);p53(KI/KI) mice develop in the absence of functional p53. Such tumors retain a functional p19(ARF)/MDM2-signaling pathway, and restoration of p53ER(TAM) allele triggers p53-tumor-suppressor activity. Congruently, growth inhibition upon normalization of mutant p53 by a small molecule, Prima-1, in human GBM cultures also requires p14(ARF)/MDM2 functionality. Notably, the antitumoral efficacy of p53 restoration in tumor-bearing GFAP-HRas(V12);p53(KI/KI) animals depends on the duration and frequency of p53 restoration. Thus, intermittent exposure to p53ER(TAM) activity mitigated the selective pressure to inactivate the p19(ARF)/MDM2/p53 pathway as a means of resistance, extending progression-free survival. Our results suggest that intermittent dosing regimes of drugs that restore wild-type tumor-suppressor function onto mutant, inactive p53 proteins will prove to be more efficacious than traditional chronic dosing by similarly reducing adaptive resistance.

  5. The Effect of Sodium Valproate on the Glioblastoma U87 Cell Line Tumor Development on the Chicken Embryo Chorioallantoic Membrane and on EZH2 and p53 Expression

    Directory of Open Access Journals (Sweden)

    Dovilė Kavaliauskaitė

    2017-01-01

    Full Text Available Literature data support evidences that glioblastoma (GBM patients experience prolonged survival due to sodium valproate (NaVP treatment. The study assessed the human GBM cell U87 xenograft studied in the chicken embryo chorioallantoic membrane (CAM model evaluating NaVP effect on tumor. Three groups of tumors (each n = 10 were studied: nontreated, treated with 4 mM, and treated with 8 mM of NaVP. The majority of tumors without NaVP treatment during tumor growth destroyed the chorionic epithelium, invaded the mesenchyme, and induced angiogenesis. Incidence of tumor formation on CAM without invasion into the mesenchyme was higher when U87 cells were treated with NaVP; the effect significantly increased with NaVP concentration. Treatment with 8 mM of NaVP did not show clear dynamics of tumor growth during 5 days; at the same time, the angiogenesis failed. With a strong staining of EZH2, p53 in tumors without NaVP treatment was found, and NaVP significantly decreased the expression of EZH2- and p53-positive cells; the effect was significantly higher at its 8 mM concentration. NaVP has a function in blocking the growth, invasion, and angiogenesis of tumor in the CAM model; tumor growth interferes with EZH2 and p53 molecular pathways, supporting the NaVP potential in GBM therapy.

  6. Reactivating p53 and Inducing Tumor Apoptosis (RITA) Enhances the Response of RITA-Sensitive Colorectal Cancer Cells to Chemotherapeutic Agents 5-Fluorouracil and Oxaliplatin.

    Science.gov (United States)

    Wiegering, Armin; Matthes, Niels; Mühling, Bettina; Koospal, Monika; Quenzer, Anne; Peter, Stephanie; Germer, Christoph-Thomas; Linnebacher, Michael; Otto, Christoph

    2017-04-01

    Colorectal carcinoma (CRC) is the most common cancer of the gastrointestinal tract with frequently dysregulated intracellular signaling pathways, including p53 signaling. The mainstay of chemotherapy treatment of CRC is 5-fluorouracil (5FU) and oxaliplatin. The two anticancer drugs mediate their therapeutic effect via DNA damage-triggered signaling. The small molecule reactivating p53 and inducing tumor apoptosis (RITA) is described as an activator of wild-type and reactivator of mutant p53 function, resulting in elevated levels of p53 protein, cell growth arrest, and cell death. Additionally, it has been shown that RITA can induce DNA damage signaling. It is expected that the therapeutic benefits of 5FU and oxaliplatin can be increased by enhancing DNA damage signaling pathways. Therefore, we highlighted the antiproliferative response of RITA alone and in combination with 5FU or oxaliplatin in human CRC cells. A panel of long-term established CRC cell lines (n=9) including p53 wild-type, p53 mutant, and p53 null and primary patient-derived, low-passage cell lines (n=5) with different p53 protein status were used for this study. A substantial number of CRC cells with pronounced sensitivity to RITA (IC 50 RITA appeared independent of p53 status and was associated with an increase in antiproliferative response to 5FU and oxaliplatin, a transcriptional increase of p53 targets p21 and NOXA, and a decrease in MYC mRNA. The effect of RITA as an inducer of DNA damage was shown by a strong elevation of phosphorylated histone variant H2A.X, which was restricted to RITA-sensitive cells. Our data underline the primary effect of RITA, inducing DNA damage, and demonstrate the differential antiproliferative effect of RITA to CRC cells independent of p53 protein status. We found a substantial number of RITA-sensitive CRC cells within both panels of established CRC cell lines and primary patient-derived CRC cell lines (6/14) that provide a rationale for combining RITA with 5FU or

  7. The critical role of catalase in prooxidant and antioxidant function of p53

    Science.gov (United States)

    Kang, M Y; Kim, H-B; Piao, C; Lee, K H; Hyun, J W; Chang, I-Y; You, H J

    2013-01-01

    The tumor suppressor p53 is an important regulator of intracellular reactive oxygen species (ROS) levels, although downstream mediators of p53 remain to be elucidated. Here, we show that p53 and its downstream targets, p53-inducible ribonucleotide reductase (p53R2) and p53-inducible gene 3 (PIG3), physically and functionally interact with catalase for efficient regulation of intracellular ROS, depending on stress intensity. Under physiological conditions, the antioxidant functions of p53 are mediated by p53R2, which maintains increased catalase activity and thereby protects against endogenous ROS. After genotoxic stress, high levels of p53 and PIG3 cooperate to inhibit catalase activity, leading to a shift in the oxidant/antioxidant balance toward an oxidative status, which could augment apoptotic cell death. These results highlight the essential role of catalase in p53-mediated ROS regulation and suggest that the p53/p53R2–catalase and p53/PIG3–catalase pathways are critically involved in intracellular ROS regulation under physiological conditions and during the response to DNA damage, respectively. PMID:22918438

  8. Rescue of the apoptotic-inducing function of mutant p53 by small molecule RITA.

    Science.gov (United States)

    Zhao, Carolyn Y; Grinkevich, Vera V; Nikulenkov, Fedor; Bao, Wenjie; Selivanova, Galina

    2010-05-01

    Expression of mutant p53 correlates with poor prognosis in many tumors, therefore strategies aimed at reactivation of mutant p53 are likely to provide important benefits for treatment of tumors that are resistant to chemotherapy and radiotherapy. We have previously identified and characterized a small molecule RITA which binds p53 and induces a conformational change which prevents the binding of p53 to several inhibitors, including its own destructor MDM2. In this way, RITA rescues the tumor suppression function of wild type p53. Here, we demonstrate that RITA suppressed the growth and induced apoptosis in human tumor cell lines of a diverse origin carrying mutant p53 proteins. RITA restored transcriptional transactivation and transrepression function of several hot spot p53 mutants. The ability of RITA to rescue the activity of different p53 mutants suggests its generic mechanism of action. Thus, RITA is a promising lead for the development of anti-cancer drugs that reactivate the tumor suppressor function of p53 in cancer cells irrespective whether they express mutant or wild type p53.

  9. Mathematical Modeling of E6-p53 interactions in Cervical Cancer

    Science.gov (United States)

    Khattak, Faryal; Haseeb, Muhammad; Fazal, Sahar; Bhatti, A I; Ullah, Mukhtar

    2017-04-01

    Background: Cervical cancer is the third most common cancer in women throughout the world. The human papillomavirus (HPV) E6 viral protein plays an essential role in proteasomal degradation of the cancer suppressant protein p53. As a result, p53 negative regulation and apoptosis relevant activities are abrogated, facilitating development of cervical cancer. Methods: A mathematical model of E6-p53 interactions was developed using mathematical laws. In-silico simulations were carried out on CellDesigner and as a test case the small molecule drug RITA was considered for its ability to rescue the functions of tumor suppressor p53 by inhibiting E6 mediated proteasomal degradation. Results: Using a computational model we scrutinized how p53 responds to RITA, and chemical reactions of this small molecule drug were incorporated to perceive the full effects. The evolved strategy allowed the p53 response and rescue of its tumor suppressor function to be delineated, RITA being found to block p53 interactions with E6 associated proteins. Conclusion: We could develop a model of E6-p53 interactions with incorporation of actions of the small molecule drug RITA. Suppression of E6 associated proteins by RITA induces accumulation of tumor suppressant p53. Using CellDesigner to encode the model ensured that it can be easily modified and extended as more data become available. This strategy should play an effective role in the development of therapies against cancer. Creative Commons Attribution License

  10. The expanding universe of p53 targets.

    Science.gov (United States)

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

    2009-10-01

    The p53 tumour suppressor is modified through mutation or changes in expression in most cancers, leading to the altered regulation of hundreds of genes that are directly influenced by this sequence-specific transcription factor. Central to the p53 master regulatory network are the target response element (RE) sequences. The extent of p53 transactivation and transcriptional repression is influenced by many factors, including p53 levels, cofactors and the specific RE sequences, all of which contribute to the role that p53 has in the aetiology of cancer. This Review describes the identification and functionality of REs and highlights the inclusion of non-canonical REs that expand the universe of genes and regulation mechanisms in the p53 tumour suppressor network.

  11. hSSB1 regulates both the stability and the transcriptional activity of p53

    OpenAIRE

    Xu, Shuangbing; Wu, Yuanzhong; Chen, Qiong; Cao, Jingying; Hu, Kaishun; Tang, Jianjun; Sang, Yi; Lai, Fenju; Wang, Li; Zhang, Ruhua; Li, Sheng-Ping; Zeng, Yi-Xin; Yin, Yuxin; Kang, Tiebang

    2012-01-01

    The tumor suppressor p53 is essential for several cellular processes that are involved in the response to diverse genotoxic stress, including cell cycle arrest, DNA repair, apoptosis and senescence. Studies of the regulation of p53 have mostly focused on its stability and transactivation; however, new regulatory molecules for p53 have also been frequently identified. Here, we report that human ssDNA binding protein SSB1 (hSSB1), a novel DNA damage-associated protein, can interact with p53 and...

  12. Genetic Stabilization by p53 Involves Growth Regulatory and Repair Pathways

    Directory of Open Access Journals (Sweden)

    Lisa Wiesmüller

    2001-01-01

    Full Text Available p53 performs a plethora of activities, which are directed towards the maintenance of the genomic integrity and constitute its universal role as a tumor suppressor. 1000 to 10000 latent p53 molecules are permanently available in order to monitor DNA exchange processes in mitotically growing cells. After the introduction of major DNA injuries the levels of posttranslationally modified p53 proteins rise, which in turn transcriptionally signal transient cell cycle arrest or apoptotic cell death, depending on the extent of damage. Taken together, p53 inhibits the manifestation of genomic instabilities at different control levels both during naturally occurring metabolic processes and in response to genotoxic treatments.

  13. 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...... tumors from smokers and 13 of 40 (33%) tumors from lifetime nonsmokers. Overall, 13 of the 50 (26%) total point mutations discovered in this and previous work were G:C-->C:G transversions, a relatively rare mutational type in human tumors. In six tumors, identical AGA (Arg)-->ACA (Thr) point mutations...... double mutations, four of which were tandem mutations on the same allele. No double mutations were found in tumors from nonsmoking patients. None of the mutations in smokers were G:C-->T:A transversions, which would be anticipated for exposure to the suspected cigarette smoke carcinogen 4-aminobiphenyl...

  14. Functions of MDMX in the Modulation of the p53-Response

    Directory of Open Access Journals (Sweden)

    Kristiaan Lenos

    2011-01-01

    Full Text Available The MDM family proteins MDM2 and MDMX are two critical regulators of the p53 tumor suppressor protein. Expression of both proteins is necessary for allowing the embryonal development by keeping the activity of p53 in check. Upon stresses that need to activate p53 to perform its function as guardian of the genome, p53 has to be liberated from these two inhibitors. In this review, we will discuss the various mechanisms by which MDMX protein levels are downregulated upon various types of stress, including posttranslational modifications of the MDMX protein and the regulation of mdmx mRNA expression, including alternative splicing. In addition, the putative function(s of the described MDMX splice variants, particularly in tumor development, will be discussed. Lastly, in contrast to common belief, we have recently shown the existence of a p53-MDMX feedback loop, which is important for dampening the p53-response at later phases after genotoxic stress.

  15. p53 and the pathogenesis of skin cancer

    International Nuclear Information System (INIS)

    Benjamin, Cara L.; Ananthaswamy, Honnavara N.

    2007-01-01

    The p53 tumor suppressor gene and gene product are among the most diverse and complex molecules involved in cellular functions. Genetic alterations within the p53 gene have been shown to have a direct correlation with cancer development and have been shown to occur in nearly 50% of all cancers. p53 mutations are particularly common in skin cancers and UV irradiation has been shown to be a primary cause of specific 'signature' mutations that can result in oncogenic transformation. There are certain 'hot-spots' in the p53 gene where mutations are commonly found that result in a mutated dipyrimidine site. This review discusses the role of p53 from normal function and its dysfunction in pre-cancerous lesions and non-melanoma skin cancers. Additionally, special situations are explored, such as Li-Fraumeni syndrome in which there is an inherited p53 mutation, and the consequences of immune suppression on p53 mutations and the resulting increase in non-melanoma skin cancer in these patients

  16. CLCA2 as a p53-Inducible Senescence Mediator

    Directory of Open Access Journals (Sweden)

    Chizu Tanikawa

    2012-02-01

    Full Text Available p53 is a tumor suppressor gene that is frequently mutated in multiple cancer tissues. Activated p53 protein regulates its downstream genes and subsequently inhibits malignant transformation by inducing cell cycle arrest, apoptosis, DNA repair, and senescence. However, genes involved in the p53-mediated senescence pathway are not yet fully elucidated. Through the screening of two genome-wide expression profile data sets, one for cells in which exogenous p53 was introduced and the other for senescent fibroblasts, we have identified chloride channel accessory 2 (CLCA2 as a p53-inducible senescence-associated gene. CLCA2 was remarkably induced by replicative senescence as well as oxidative stress in a p53-dependent manner. We also found that ectopically expressed CLCA2 induced cellular senescence, and the down-regulation of CLCA2 by small interfering RNA caused inhibition of oxidative stress-induced senescence. Interestingly, the reduced expression of CLCA2 was frequently observed in various kinds of cancers including prostate cancer, whereas its expression was not affected in precancerous prostatic intraepithelial neoplasia. Thus, our findings suggest a crucial role of p53/CLCA2-mediated senescence induction as a barrier for malignant transformation.

  17. Off and back-on again: a tumor suppressor's tale.

    Science.gov (United States)

    Acosta, Jonuelle; Wang, Walter; Feldser, David M

    2018-06-01

    Tumor suppressor genes play critical roles orchestrating anti-cancer programs that are both context dependent and mechanistically diverse. Beyond canonical tumor suppressive programs that control cell division, cell death, and genome stability, unexpected tumor suppressor gene activities that regulate metabolism, immune surveillance, the epigenetic landscape, and others have recently emerged. This diversity underscores the important roles these genes play in maintaining cellular homeostasis to suppress cancer initiation and progression, but also highlights a tremendous challenge in discerning precise context-specific programs of tumor suppression controlled by a given tumor suppressor. Fortunately, the rapid sophistication of genetically engineered mouse models of cancer has begun to shed light on these context-dependent tumor suppressor activities. By using techniques that not only toggle "off" tumor suppressor genes in nascent tumors, but also facilitate the timely restoration of gene function "back-on again" in disease specific contexts, precise mechanisms of tumor suppression can be revealed in an unbiased manner. This review discusses the development and implementation of genetic systems designed to toggle tumor suppressor genes off and back-on again and their potential to uncover the tumor suppressor's tale.

  18. Expression of arf tumor suppressor in spermatogonia facilitates meiotic progression in male germ cells.

    Directory of Open Access Journals (Sweden)

    Michelle L Churchman

    2011-07-01

    Full Text Available The mammalian Cdkn2a (Ink4a-Arf locus encodes two tumor suppressor proteins (p16(Ink4a and p19(Arf that respectively enforce the anti-proliferative functions of the retinoblastoma protein (Rb and the p53 transcription factor in response to oncogenic stress. Although p19(Arf is not normally detected in tissues of young adult mice, a notable exception occurs in the male germ line, where Arf is expressed in spermatogonia, but not in meiotic spermatocytes arising from them. Unlike other contexts in which the induction of Arf potently inhibits cell proliferation, expression of p19(Arf in spermatogonia does not interfere with mitotic cell division. Instead, inactivation of Arf triggers germ cell-autonomous, p53-dependent apoptosis of primary spermatocytes in late meiotic prophase, resulting in reduced sperm production. Arf deficiency also causes premature, elevated, and persistent accumulation of the phosphorylated histone variant H2AX, reduces numbers of chromosome-associated complexes of Rad51 and Dmc1 recombinases during meiotic prophase, and yields incompletely synapsed autosomes during pachynema. Inactivation of Ink4a increases the fraction of spermatogonia in S-phase and restores sperm numbers in Ink4a-Arf doubly deficient mice but does not abrogate γ-H2AX accumulation in spermatocytes or p53-dependent apoptosis resulting from Arf inactivation. Thus, as opposed to its canonical role as a tumor suppressor in inducing p53-dependent senescence or apoptosis, Arf expression in spermatogonia instead initiates a salutary feed-forward program that prevents p53-dependent apoptosis, contributing to the survival of meiotic male germ cells.

  19. p53-independent early and late apoptosis is mediated by ceramide after exposure of tumor cells to photon or carbon ion irradiation

    International Nuclear Information System (INIS)

    Alphonse, Gersende; Maalouf, Mira; Battiston-Montagne, Priscillia; Ardail, Dominique; Beuve, Michaël; Rousson, Robert; Taucher-Scholz, Gisela; Fournier, Claudia; Rodriguez-Lafrasse, Claire

    2013-01-01

    To determine whether ceramide is responsible for the induction of p53-independent early or late apoptosis in response to high- and low-Linear-Energy-Transfer (LET) irradiation. Four cell lines displaying different radiosensitivities and p53-protein status were irradiated with photons or 33.4 or 184 keV/μm carbon ions. The kinetics of ceramide production was quantified by fluorescent microscopy or High-Performance-Liquid-Chromatogaphy and the sequence of events leading to apoptosis by flow cytometry. Regardless of the p53-status, both low and high-LET irradiation induced an early ceramide production in radiosensitive cells and late in the radioresistant. This production strongly correlated with the level of early apoptosis in radiosensitive cells and delayed apoptosis in the radioresistant ones, regardless of radiation quality, tumor type, radiosensitivity, or p53-status. Inhibition of caspase activity or ceramide production showed that, for both types of radiation, ceramide is essential for the initiation of early apoptosis in radiosensitive cells and late apoptosis following mitotic catastrophe in radioresistant cells. Ceramide is a determining factor in the onset of early and late apoptosis after low and high-LET irradiation and is the mediator of the p53-independent-apoptotic pathway. We propose that ceramide is the molecular bridge between mitotic catastrophe and the commitment phase of delayed apoptosis in response to irradiation

  20. p53 and ARF: Unexpected players in autophagy

    OpenAIRE

    Balaburski, Gregor M.; Hontz, Robert D.; Murphy, Maureen E.

    2010-01-01

    p53 and ARF are well-established tumor suppressor proteins that function together in the negative regulation of cancer. Recently, both of these proteins were found to play surprising roles in autophagy. Autophagy (“self-eating”) is a critical response of eukaryotic cells to metabolic and other stress. During this process, portions of the cytosol are sequestered into characteristic double membrane vesicles that are delivered to the lysosome for degradation, leading to the release of free amino...

  1. Caracterização patológica e gênica (gene P53) dos tumores mamários em cadelas.

    OpenAIRE

    Daniela Maria Bastos de Souza

    2006-01-01

    Os tumores mamários em cadelas tem alta incidência e malignidade sendo provocados por vários fatores de risco incluindo idade, atividade hormonal, nutrição, vírus, pseudogestação e administração de progestágenos exógenos. O gene p53, conhecido como um gene supressor de tumor, tem apresentado mutações relacionadas com neoplasias. Neste trabalho, o objetivo foi caracterizar os tumores mamários em cadelas, avaliar o comprometimento da mama lateral ao tumor e o envolvimento de fatores de risco...

  2. RASSF6; the Putative Tumor Suppressor of the RASSF Family

    Directory of Open Access Journals (Sweden)

    Hiroaki Iwasa

    2015-12-01

    Full Text Available Humans have 10 genes that belong to the Ras association (RA domain family (RASSF. Among them, RASSF7 to RASSF10 have the RA domain in the N-terminal region and are called the N-RASSF proteins. In contradistinction to them, RASSF1 to RASSF6 are referred to as the C-RASSF proteins. The C-RASSF proteins have the RA domain in the middle region and the Salvador/RASSF/Hippo domain in the C-terminal region. RASSF6 additionally harbors the PSD-95/Discs large/ZO-1 (PDZ-binding motif. Expression of RASSF6 is epigenetically suppressed in human cancers and is generally regarded as a tumor suppressor. RASSF6 induces caspase-dependent and -independent apoptosis. RASSF6 interacts with mammalian Ste20-like kinases (homologs of Drosophila Hippo and cross-talks with the Hippo pathway. RASSF6 binds MDM2 and regulates p53 expression. The interactions with Ras and Modulator of apoptosis 1 (MOAP1 are also suggested by heterologous protein-protein interaction experiments. RASSF6 regulates apoptosis and cell cycle through these protein-protein interactions, and is implicated in the NF-κB and JNK signaling pathways. We summarize our current knowledge about RASSF6 and discuss what common and different properties RASSF6 and the other C-RASSF proteins have.

  3. The p53 gene with emphasis on its paralogues in mosquitoes

    Directory of Open Access Journals (Sweden)

    Tien-Huang Chen

    2017-12-01

    Full Text Available The p53 gene is highly important in human cancers, as it serves as a tumor-suppressor gene. Subsequently, two p53 homologues, i.e., p73 and p63, with high identity of amino acids were identified, leading to construction of the p53 family. The p53 gene is highly important in human cancer because it usually transcribes genes that function by causing apoptosis in mammalian cells. In contrast, p63 and p73 tend to be more important in modulating development than inducing cell death, even though they share similar protein structures. Relatively recently, p53 was also identified in mosquitoes and many other insect species. Uniquely, its structure lacks the sterile alpha motif domain which is a putative protein-protein interaction domain and exclusively exists at the C-terminal region in p73 and p63 in mammals. A phylogenetic analysis revealed that the p53 gene derived from mosquitoes is composed of two paralogues, p53-1 and p53-2. Of these, only p53-2 is responsively upregulated by dengue 2 virus (DENV2 in C6/36 cells which usually survive the infection. This indicates that the p53 gene is closely related to DENV infection in mosquito cells. The specific significance of p53-2's involvement in cell survival from virus-induced stress is described and briefly discussed in this report. Keywords: p53 homologue, Paralogue, Mosquitoes, Phylogeny, Cell survival

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

    Science.gov (United States)

    2006-10-01

    then sequenced (for GeneChip- positiv SSCP (for GeneChip-negative). We have received a total of 43 core breast biopsy DNA samples from the UNC... quantitative luciferase reporter. Both reporters exploit a “rheostatable” promoter for p53 expression and utilize the “delitto perfetto” in vivo... quantitative luciferase-based assay is also being used to characterize the altered function sistent an tion T mutants in greater detail. Preliminary

  5. 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.

  6. p53 Acetylation: Regulation and Consequences

    International Nuclear Information System (INIS)

    Reed, Sara M.; Quelle, Dawn E.

    2014-01-01

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

  7. Characterization of Two Novel Oncogenic Pathways Collaborating With Loss of P53 or Activated Neu in Mouse Models of Breast Cancer

    National Research Council Canada - National Science Library

    Lu, Jianrong; Leder, Philip

    2005-01-01

    Cancer develops through accumulation of multiple genetic mutations. Loss of tumor suppressor gene p53 and activation of oncogene Neu/ErbB2 are among the most frequent genetic alterations in human breast cancer...

  8. Increased Arf/p53 activity in stem cells, aging and cancer.

    Science.gov (United States)

    Carrasco-Garcia, Estefania; Moreno, Manuel; Moreno-Cugnon, Leire; Matheu, Ander

    2017-04-01

    Arf/p53 pathway protects the cells against DNA damage induced by acute stress. This characteristic is the responsible for its tumor suppressor activity. Moreover, it regulates the chronic type of stress associated with aging. This is the basis of its anti-aging activity. Indeed, increased gene dosage of Arf/p53 displays elongated longevity and delayed aging. At a cellular level, it has been recently shown that increased dosage of Arf/p53 delays age-associated stem cell exhaustion and the subsequent decline in tissue homeostasis and regeneration. However, p53 can also promote aging if constitutively activated. In this context, p53 reduces tissue regeneration, which correlates with premature exhaustion of stem cells. We discuss here the current evidence linking the Arf/p53 pathway to the processes of aging and cancer through stem cell regulation. © 2017 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  9. Ensemble-based computational approach discriminates functional activity of p53 cancer and rescue mutants.

    Directory of Open Access Journals (Sweden)

    Özlem Demir

    2011-10-01

    Full Text Available The tumor suppressor protein p53 can lose its function upon single-point missense mutations in the core DNA-binding domain ("cancer mutants". Activity can be restored by second-site suppressor mutations ("rescue mutants". This paper relates the functional activity of p53 cancer and rescue mutants to their overall molecular dynamics (MD, without focusing on local structural details. A novel global measure of protein flexibility for the p53 core DNA-binding domain, the number of clusters at a certain RMSD cutoff, was computed by clustering over 0.7 µs of explicitly solvated all-atom MD simulations. For wild-type p53 and a sample of p53 cancer or rescue mutants, the number of clusters was a good predictor of in vivo p53 functional activity in cell-based assays. This number-of-clusters (NOC metric was strongly correlated (r(2 = 0.77 with reported values of experimentally measured ΔΔG protein thermodynamic stability. Interpreting the number of clusters as a measure of protein flexibility: (i p53 cancer mutants were more flexible than wild-type protein, (ii second-site rescue mutations decreased the flexibility of cancer mutants, and (iii negative controls of non-rescue second-site mutants did not. This new method reflects the overall stability of the p53 core domain and can discriminate which second-site mutations restore activity to p53 cancer mutants.

  10. Post-translational regulation enables robust p53 regulation.

    Science.gov (United States)

    Shin, Yong-Jun; Chen, Kai-Yuan; Sayed, Ali H; Hencey, Brandon; Shen, Xiling

    2013-08-30

    The tumor suppressor protein p53 plays important roles in DNA damage repair, cell cycle arrest and apoptosis. Due to its critical functions, the level of p53 is tightly regulated by a negative feedback mechanism to increase its tolerance towards fluctuations and disturbances. Interestingly, the p53 level is controlled by post-translational regulation rather than transcriptional regulation in this feedback mechanism. We analyzed the dynamics of this feedback to understand whether post-translational regulation provides any advantages over transcriptional regulation in regard to disturbance rejection. When a disturbance happens, even though negative feedback reduces the steady-state error, it can cause a system to become less stable and transiently overshoots, which may erroneously trigger downstream reactions. Therefore, the system needs to balance the trade-off between steady-state and transient errors. Feedback control and adaptive estimation theories revealed that post-translational regulation achieves a better trade-off than transcriptional regulation, contributing to a more steady level of p53 under the influence of noise and disturbances. Furthermore, post-translational regulation enables cells to respond more promptly to stress conditions with consistent amplitude. However, for better disturbance rejection, the p53- Mdm2 negative feedback has to pay a price of higher stochastic noise. Our analyses suggest that the p53-Mdm2 feedback favors regulatory mechanisms that provide the optimal trade-offs for dynamic control.

  11. 40 Years of Research Put p53 in Translation

    Science.gov (United States)

    Marcel, Virginie; Nguyen Van Long, Flora; Diaz, Jean-Jacques

    2018-01-01

    Since its discovery in 1979, p53 has shown multiple facets. Initially the tumor suppressor p53 protein was considered as a stress sensor able to maintain the genome integrity by regulating transcription of genes involved in cell cycle arrest, apoptosis and DNA repair. However, it rapidly came into light that p53 regulates gene expression to control a wider range of biological processes allowing rapid cell adaptation to environmental context. Among them, those related to cancer have been extensively documented. In addition to its role as transcription factor, scattered studies reported that p53 regulates miRNA processing, modulates protein activity by direct interaction or exhibits RNA-binding activity, thus suggesting a role of p53 in regulating several layers of gene expression not restricted to transcription. After 40 years of research, it appears more and more clearly that p53 is strongly implicated in translational regulation as well as in the control of the production and activity of the translational machinery. Translation control of specific mRNAs could provide yet unsuspected capabilities to this well-known guardian of the genome.

  12. 2-Sulfonylpyrimidines: Mild alkylating agents with anticancer activity toward p53-compromised cells.

    Science.gov (United States)

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

    2016-09-06

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

  13. Nuclear accumulation and activation of p53 in embryonic stem cells after DNA damage

    Directory of Open Access Journals (Sweden)

    Rolletschek Alexandra

    2009-06-01

    Full Text Available Abstract Background P53 is a key tumor suppressor protein. In response to DNA damage, p53 accumulates to high levels in differentiated cells and activates target genes that initiate cell cycle arrest and apoptosis. Since stem cells provide the proliferative cell pool within organisms, an efficient DNA damage response is crucial. Results In proliferating embryonic stem cells, p53 is localized predominantly in the cytoplasm. DNA damage-induced nuclear accumulation of p53 in embryonic stem cells activates transcription of the target genes mdm2, p21, puma and noxa. We observed bi-phasic kinetics for nuclear accumulation of p53 after ionizing radiation. During the first wave of nuclear accumulation, p53 levels were increased and the p53 target genes mdm2, p21 and puma were transcribed. Transcription of noxa correlated with the second wave of nuclear accumulation. Transcriptional activation of p53 target genes resulted in an increased amount of proteins with the exception of p21. While p21 transcripts were efficiently translated in 3T3 cells, we failed to see an increase in p21 protein levels after IR in embryonal stem cells. Conclusion In embryonic stem cells where (anti-proliferative p53 activity is not necessary, or even unfavorable, p53 is retained in the cytoplasm and prevented from activating its target genes. However, if its activity is beneficial or required, p53 is allowed to accumulate in the nucleus and activates its target genes, even in embryonic stem cells.

  14. Nuclear accumulation and activation of p53 in embryonic stem cells after DNA damage.

    Science.gov (United States)

    Solozobova, Valeriya; Rolletschek, Alexandra; Blattner, Christine

    2009-06-17

    P53 is a key tumor suppressor protein. In response to DNA damage, p53 accumulates to high levels in differentiated cells and activates target genes that initiate cell cycle arrest and apoptosis. Since stem cells provide the proliferative cell pool within organisms, an efficient DNA damage response is crucial. In proliferating embryonic stem cells, p53 is localized predominantly in the cytoplasm. DNA damage-induced nuclear accumulation of p53 in embryonic stem cells activates transcription of the target genes mdm2, p21, puma and noxa. We observed bi-phasic kinetics for nuclear accumulation of p53 after ionizing radiation. During the first wave of nuclear accumulation, p53 levels were increased and the p53 target genes mdm2, p21 and puma were transcribed. Transcription of noxa correlated with the second wave of nuclear accumulation. Transcriptional activation of p53 target genes resulted in an increased amount of proteins with the exception of p21. While p21 transcripts were efficiently translated in 3T3 cells, we failed to see an increase in p21 protein levels after IR in embryonal stem cells. In embryonic stem cells where (anti-proliferative) p53 activity is not necessary, or even unfavorable, p53 is retained in the cytoplasm and prevented from activating its target genes. However, if its activity is beneficial or required, p53 is allowed to accumulate in the nucleus and activates its target genes, even in embryonic stem cells.

  15. p53-competent cells and p53-deficient cells display different susceptibility to oxygen functionalized graphene cytotoxicity and genotoxicity.

    Science.gov (United States)

    Petibone, Dayton M; Mustafa, Thikra; Bourdo, Shawn E; Lafont, Andersen; Ding, Wei; Karmakar, Alokita; Nima, Zeid A; Watanabe, Fumiya; Casciano, Daniel; Morris, Suzanne M; Dobrovolsky, Vasily N; Biris, Alexandru S

    2017-11-01

    Due to the distinctive physical, electrical, and chemical properties of graphene nanomaterials, numerous efforts pursuing graphene-based biomedical and industrial applications are underway. Oxidation of pristine graphene surfaces mitigates its otherwise hydrophobic characteristic thereby improving its biocompatibility and functionality. Yet, the potential widespread use of oxidized graphene derivatives raises concern about adverse impacts on human health. The p53 tumor suppressor protein maintains cellular and genetic stability after toxic exposures. Here, we show that p53 functional status correlates with oxygen functionalized graphene (f-G) cytotoxicity and genotoxicity in vitro. The f-G exposed p53-competent cells, but not p53-deficient cells, initiated G 0 /G 1 phase cell cycle arrest, suppressed reactive oxygen species, and entered apoptosis. There was p53-dependent f-G genotoxicity evident as increased structural chromosome damage, but not increased gene mutation or chromatin loss. In conclusion, the cytotoxic and genotoxic potential for f-G in exposed cells was dependent on the p53 functional status. These findings have broad implications for the safe and effective implementation of oxidized graphene derivatives into biomedical and industrial applications. Published 2017. This article has been contributed to by US Government employees and their work is in the public domain in the USA. Published 2017. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

  16. Mitochondrial DNA maintenance is regulated in human hepatoma cells by glycogen synthase kinase 3β and p53 in response to tumor necrosis factor α.

    Science.gov (United States)

    Vadrot, Nathalie; Ghanem, Sarita; Braut, Françoise; Gavrilescu, Laura; Pilard, Nathalie; Mansouri, Abdellah; Moreau, Richard; Reyl-Desmars, Florence

    2012-01-01

    During chronic liver inflammation, up-regulated Tumor Necrosis Factor alpha (TNF-α) targets hepatocytes and induces abnormal reactive oxygen species (ROS) production responsible for mitochondrial DNA (mtDNA) alterations. The serine/threonine Glycogen Synthase Kinase 3 beta (GSK3β) plays a pivotal role during inflammation but its involvement in the maintenance of mtDNA remains unknown. The aim of this study was to investigate its involvement in TNF-α induced mtDNA depletion and its interrelationship with p53 a protein known to maintain mtDNA copy numbers. Using quantitative polymerase chain reaction (qPCR) we found that at 30 min in human hepatoma HepG2 cells TNF-α induced 0.55±0.10 mtDNA lesions per 10 Kb and a 52.4±2.8% decrease in mtDNA content dependent on TNF-R1 receptor and ROS production. Both lesions and depletion returned to baseline from 1 to 6 h after TNF-α exposure. Luminol-amplified chemiluminescence (LAC) was used to measure the rapid (10 min) and transient TNF-α induced increase in ROS production (168±15%). A transient 8-oxo-dG level of 1.4±0.3 ng/mg DNA and repair of abasic sites were also measured by ELISA assays. Translocation of p53 to mitochondria was observed by Western Blot and co-immunoprecipitations showed that TNF-α induced p53 binding to GSK3β and mitochondrial transcription factor A (TFAM). In addition, mitochondrial D-loop immunoprecipitation (mtDIP) revealed that TNF-α induced p53 binding to the regulatory D-loop region of mtDNA. The knockdown of p53 by siRNAs, inhibition by the phosphoSer(15)p53 antibody or transfection of human mutant active GSK3βS9A pcDNA3 plasmid inhibited recovery of mtDNA content while blockade of GSK3β activity by SB216763 inhibitor or knockdown by siRNAs suppressed mtDNA depletion. This study is the first to report the involvement of GSK3β in TNF-α induced mtDNA depletion. We suggest that p53 binding to GSK3β, TFAM and D-loop could induce recovery of mtDNA content through mtDNA repair.

  17. Mitochondrial DNA maintenance is regulated in human hepatoma cells by glycogen synthase kinase 3β and p53 in response to tumor necrosis factor α.

    Directory of Open Access Journals (Sweden)

    Nathalie Vadrot

    Full Text Available During chronic liver inflammation, up-regulated Tumor Necrosis Factor alpha (TNF-α targets hepatocytes and induces abnormal reactive oxygen species (ROS production responsible for mitochondrial DNA (mtDNA alterations. The serine/threonine Glycogen Synthase Kinase 3 beta (GSK3β plays a pivotal role during inflammation but its involvement in the maintenance of mtDNA remains unknown. The aim of this study was to investigate its involvement in TNF-α induced mtDNA depletion and its interrelationship with p53 a protein known to maintain mtDNA copy numbers. Using quantitative polymerase chain reaction (qPCR we found that at 30 min in human hepatoma HepG2 cells TNF-α induced 0.55±0.10 mtDNA lesions per 10 Kb and a 52.4±2.8% decrease in mtDNA content dependent on TNF-R1 receptor and ROS production. Both lesions and depletion returned to baseline from 1 to 6 h after TNF-α exposure. Luminol-amplified chemiluminescence (LAC was used to measure the rapid (10 min and transient TNF-α induced increase in ROS production (168±15%. A transient 8-oxo-dG level of 1.4±0.3 ng/mg DNA and repair of abasic sites were also measured by ELISA assays. Translocation of p53 to mitochondria was observed by Western Blot and co-immunoprecipitations showed that TNF-α induced p53 binding to GSK3β and mitochondrial transcription factor A (TFAM. In addition, mitochondrial D-loop immunoprecipitation (mtDIP revealed that TNF-α induced p53 binding to the regulatory D-loop region of mtDNA. The knockdown of p53 by siRNAs, inhibition by the phosphoSer(15p53 antibody or transfection of human mutant active GSK3βS9A pcDNA3 plasmid inhibited recovery of mtDNA content while blockade of GSK3β activity by SB216763 inhibitor or knockdown by siRNAs suppressed mtDNA depletion. This study is the first to report the involvement of GSK3β in TNF-α induced mtDNA depletion. We suggest that p53 binding to GSK3β, TFAM and D-loop could induce recovery of mtDNA content through mtDNA repair.

  18. Correlation analysis of expressions of PTEN and p53 with the value obtained by magnetic resonance spectroscopy and apparent diffusion coefficient in the tumor and the tumor-adjacent area in magnetic resonance imaging for glioblastoma.

    Science.gov (United States)

    Li, Yunyun; Ji, Feng; Jiang, Yuzhi; Zhao, Ting; Xu, Chongfu

    2018-01-01

    To explore the correlation of the expression levels of phosphate and tension homology deleted on chromosome ten (PTEN) and p53 of glioblastoma multiforme (GBM) with the value obtained by magnetic resonance spectroscopy (MRS) and apparent diffusion coefficient (ADC) in the tumor and the tumor-adjacent area in magnetic resonance imaging (MRI). A total of 38 patients were operated for GBM. All the patients had received diffusion-weighted imaging (DWI) and MRS prior to surgery. ADC of water molecules and values of metabolite indexes of MRS, including n-acetyl aspartate (NAA), choline (Cho) and creatine (Cr), were recorded, and the ratios of Cho/NAA, Cho/Cr and NAA/Cr were calculated. Hematoxylin-eosin (H&E) staining was done to examine the morphology of tumor and of tumor-adjacent tissues; immunohistochemistry (IHC) was performed to examine the expressions of PTEN and p53 in the tumor and the tumor-adjacent area. Finally, the correlations of the expressions of PTEN and p53 with ADC, Cho/NAA, Cho/Cr and NAA/Cr of the tumor and the tumor-adjacent area were analyzed. H&E staining showed that GBM tissues had disordered morphology, different sizes of cells, large cell nuclei and significant cell heterogeneity. IHC indicated that the expression level of p53 protein in the tumor was significantly higher than in the tumor-adjacent tissues (pCorrelation analysis indicated that PTEN levels in the tumor and the tumor-adjacent area were positively correlated with ADC in the corresponding area, while p53 in the tumor and the tumor-adjacent area was negatively correlated with ADC in the corresponding area. Cho/NAA and Cho/Cr in the tumor were positively correlated with p53 in the tumor, but negatively correlated with PTEN in the tumor. However, NAA/Cr of the tumor was irrelevant to the levels of PTEN and p53. The test results of DWI and MRS of patients with GBM can accurately reflect the inactivation or mutation of PTEN and p53.

  19. 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.

  20. 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.

  1. Molecular Dynamic Simulation Insights into the Normal State and Restoration of p53 Function

    Directory of Open Access Journals (Sweden)

    Jianzhong Chen

    2012-08-01

    Full Text Available As a tumor suppressor protein, p53 plays a crucial role in the cell cycle and in cancer prevention. Almost 50 percent of all human malignant tumors are closely related to a deletion or mutation in p53. The activity of p53 is inhibited by over-active celluar antagonists, especially by the over-expression of the negative regulators MDM2 and MDMX. Protein-protein interactions, or post-translational modifications of the C-terminal negative regulatory domain of p53, also regulate its tumor suppressor activity. Restoration of p53 function through peptide and small molecular inhibitors has become a promising strategy for novel anti-cancer drug design and development. Molecular dynamics simulations have been extensively applied to investigate the conformation changes of p53 induced by protein-protein interactions and protein-ligand interactions, including peptide and small molecular inhibitors. This review focuses on the latest MD simulation research, to provide an overview of the current understanding of interactions between p53 and its partners at an atomic level.

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

    Science.gov (United States)

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

    2015-03-01

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

  3. The oncogenic properties of EWS/WT1 of desmoplastic small round cell tumors are unmasked by loss of p53 in murine embryonic fibroblasts

    International Nuclear Information System (INIS)

    Bandopadhayay, Pratiti; Thomas, David M; Algar, Elizabeth; Ekert, Paul G; Jabbour, Anissa M; Riffkin, Christopher; Salmanidis, Marika; Gordon, Lavinia; Popovski, Dean; Rigby, Lin; Ashley, David M; Watkins, David N

    2013-01-01

    Desmoplastic small round cell tumor (DSRCT) is characterized by the presence of a fusion protein EWS/WT1, arising from the t (11;22) (p13;q12) translocation. Here we examine the oncogenic properties of two splice variants of EWS/WT1, EWS/WT1-KTS and EWS/WT1 + KTS. We over-expressed both EWS/WT1 variants in murine embryonic fibroblasts (MEFs) of wild-type, p53 +/- and p53 -/- backgrounds and measured effects on cell-proliferation, anchorage-independent growth, clonogenicity after serum withdrawal, and sensitivity to cytotoxic drugs and gamma irradiation in comparison to control cells. We examined gene expression profiles in cells expressing EWS/WT1. Finally we validated our key findings in a small series of DSRCT. Neither isoform of EWS/WT1 was sufficient to transform wild-type MEFs however the oncogenic potential of both was unmasked by p53 loss. Expression of EWS/WT1 in MEFs lacking at least one allele of p53 enhanced cell-proliferation, clonogenic survival and anchorage-independent growth. EWS/WT1 expression in wild-type MEFs conferred resistance to cell-cycle arrest after irradiation and daunorubicin induced apoptosis. We show DSRCT commonly have nuclear localization of p53, and copy-number amplification of MDM2/MDMX. Expression of either isoform of EWS/WT1 induced characteristic mRNA expression profiles. Gene-set enrichment analysis demonstrated enrichment of WNT pathway signatures in MEFs expressing EWS/WT1 + KTS. Wnt-activation was validated in cell lines with over-expression of EWS/WT1 and in DSRCT. In conclusion, we show both isoforms of EWS/WT1 have oncogenic potential in MEFs with loss of p53. In addition we provide the first link between EWS/WT1 and Wnt-pathway signaling. These data provide novel insights into the function of the EWS/WT1 fusion protein which characterize DSRCT

  4. An N-terminal Region of Mot-2 Binds to p53 In Vitro

    Directory of Open Access Journals (Sweden)

    Sunil C. Kaul

    2001-01-01

    Full Text Available The mouse mot-2 protein was earlier shown to bind to the tumor suppressor protein, p53. The mot-2 binding site of p53 was mapped to C-terminal amino acid residues 312–352, which includes the cytoplasmic sequestration domain. In the present study, we have found that both mot-1 and mot-2 bind to p53 in vitro. By using His-tagged deletion mutant proteins, the p53-binding domain of mot-2 was mapped to its Nterminal amino acid residues 253–282, which are identical in mot-1 and mot-2 proteins. Some peptides containing the p53-binding region of mot-2 were able to compete with the full-length protein for p53 binding. The data provided rationale for in vitro binding of mot-1 and mot-2 proteins to p53 and supported the conclusion that inability of mot-1 protein to bind p53 in vivo depends on secondary structure or its binding to other cellular factors. Most interestingly, the p53-binding region of mot-2 was common to its MKT-077, a cationic dye that exhibits antitumor activity, binding region. Therefore it is most likely that MKT-077-induced nuclear translocation and restoration of wild-type p53 function in transformed cells takes place by a competitional mechanism.

  5. Down-Regulation of p53 by Double-Stranded RNA Modulates the Antiviral Response

    Science.gov (United States)

    Marques, Joao T.; Rebouillat, Dominique; Ramana, Chilakamarti V.; Murakami, Junko; Hill, Jason E.; Gudkov, Andrei; Silverman, Robert H.; Stark, George R.; Williams, Bryan R. G.

    2005-01-01

    p53 has been well characterized as a tumor suppressor gene, but its role in antiviral defense remains unclear. A recent report has demonstrated that p53 can be induced by interferons and is activated after vesicular stomatitis virus (VSV) infection. We observed that different nononcogenic viruses, including encephalomyocarditis virus (EMCV) and human parainfluenza virus type 3 (HPIV3), induced down-regulation of p53 in infected cells. Double-stranded RNA (dsRNA) and a mutant vaccinia virus lacking the dsRNA binding protein E3L can also induce this effect, indicating that dsRNA formed during viral infection is likely the trigger for down-regulation of p53. The mechanism of down-regulation of p53 by dsRNA relies on translation inhibition mediated by the PKR and RNase L pathways. In the absence of p53, the replication of both EMCV and HPIV3 was retarded, whereas, conversely, VSV replication was enhanced. Cell cycle analysis indicated that wild-type (WT) but not p53 knockout (KO) fibroblasts undergo an early-G1 arrest following dsRNA treatment. Moreover, in WT cells the onset of dsRNA-induced apoptosis begins after p53 levels are down-regulated, whereas p53 KO cells, which lack the early-G1 arrest, rapidly undergo apoptosis. Hence, our data suggest that the down-regulation of p53 facilitates apoptosis, thereby limiting viral replication. PMID:16103161

  6. Radiation-induced p53 protein response in the A549 cell line is culture growth-phase dependent

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, N.F.; Gurule, D.M.; Carpenter, T.R.

    1995-12-01

    One role of the p53 tumor suppressor protein has been recently revealed. Kastan, M.B. reported that p53 protein accumulates in cells exposed to ionizing radiation. The accumulation of p53 protein is in response to DNA damage, most importantly double-strand breaks, that results from exposure to ionizing radiation. The rise in cellular p53 levels is necessary for an arrest in the G{sub 1} phase of the cell cycle to provide additional time for DNA repair. The p53 response has also been demonstrated to enhance PCNA-dependent repair. p53 is thus an important regulator of the cellular response to DNA-damaging radiation. From this data, it can be concluded that the magnitude of the p53 response is not dependent on the phase of culture growth.

  7. Contribution to the investigation of the p53 in vivo and in vitro trans-activation activity

    International Nuclear Information System (INIS)

    Meiller, A.

    2004-03-01

    Among the body's defence mechanisms, the programmed cellular death or apoptosis is an important safeguard way which allows the body to get rid of the injured cells before they acquire steady genetic modifications leading to an anarchistic multiplication. As p53 tumor suppressor gene plays a predominant role within this process, this research report first presents the p53 protein, its structure, its activities as a transcription factor, its modifications and the implications on its functional activities, its biological activities, and describes the p53 intracellular rate regulation and the use of this protein in radiology, particularly in 'in vivo' investigations on irradiated mice. It also presents the p53 family. Then, the author reports experimental investigations on possible other genes which could be trans-activated by p53. A gene is identified as a new target gene. She also demonstrates a new p53 activation path induced by another member of the p53 family, the p73 alpha protein

  8. Macrophage p53 controls macrophage death in atherosclerotic lesions of apolipoprotein E deficient mice

    NARCIS (Netherlands)

    Boesten, L.S.M.; Zadelaar, A.S.M.; Nieuwkoop, A. van; Hu, L.; Teunisse, A.F.A.S.; Jochemsen, A.G.; Evers, B.; Water, B. van de; Gijbels, M.J.J.; Vlijmen, B.J.M. van; Havekes, L.M.; Winther, M.P.J. de

    2009-01-01

    The cellular composition of atherosclerotic lesions is determined by many factors including cell infiltration, proliferation and cell death. Tumor suppressor gene p53 has been shown to regulate both cell proliferation and cell death in many cell types. In the present study, we investigated the role

  9. Rheumatoid arthritis and p53: how oxidative stress might alter the course of inflammatory diseases

    NARCIS (Netherlands)

    Tak, P. P.; Zvaifler, N. J.; Green, D. R.; Firestein, G. S.

    2000-01-01

    Oxidative stress at sites of chronic inflammation can cause permanent genetic changes. The development of mutations in the p53 tumor suppressor gene and other key regulatory genes could help convert inflammation into chronic disease in rheumatoid arthritis and other inflammatory disorders

  10. Gene expression patterns associated with p53 status in breast cancer

    International Nuclear Information System (INIS)

    Troester, Melissa A; Herschkowitz, Jason I; Oh, Daniel S; He, Xiaping; Hoadley, Katherine A; Barbier, Claire S; Perou, Charles M

    2006-01-01

    Breast cancer subtypes identified in genomic studies have different underlying genetic defects. Mutations in the tumor suppressor p53 occur more frequently in estrogen receptor (ER) negative, basal-like and HER2-amplified tumors than in luminal, ER positive tumors. Thus, because p53 mutation status is tightly linked to other characteristics of prognostic importance, it is difficult to identify p53's independent prognostic effects. The relation between p53 status and subtype can be better studied by combining data from primary tumors with data from isogenic cell line pairs (with and without p53 function). The p53-dependent gene expression signatures of four cell lines (MCF-7, ZR-75-1, and two immortalized human mammary epithelial cell lines) were identified by comparing p53-RNAi transduced cell lines to their parent cell lines. Cell lines were treated with vehicle only or doxorubicin to identify p53 responses in both non-induced and induced states. The cell line signatures were compared with p53-mutation associated genes in breast tumors. Each cell line displayed distinct patterns of p53-dependent gene expression, but cell type specific (basal vs. luminal) commonalities were evident. Further, a common gene expression signature associated with p53 loss across all four cell lines was identified. This signature showed overlap with the signature of p53 loss/mutation status in primary breast tumors. Moreover, the common cell-line tumor signature excluded genes that were breast cancer subtype-associated, but not downstream of p53. To validate the biological relevance of the common signature, we demonstrated that this gene set predicted relapse-free, disease-specific, and overall survival in independent test data. In the presence of breast cancer heterogeneity, experimental and biologically-based methods for assessing gene expression in relation to p53 status provide prognostic and biologically-relevant gene lists. Our biologically-based refinements excluded genes

  11. Two sequence motifs from HIF-1α bind to the DNA-binding site of p53

    OpenAIRE

    Hansson, Lars O.; Friedler, Assaf; Freund, Stefan; Rüdiger, Stefan; Fersht, Alan R.

    2002-01-01

    There is evidence that hypoxia-inducible factor-1α (HIF-1α) interacts with the tumor suppressor p53. To characterize the putative interaction, we mapped the binding of the core domain of p53 (p53c) to an array of immobilized HIF-1α-derived peptides and found two peptide-sequence motifs that bound to p53c with micromolar affinity in solution. One sequence was adjacent to and the other coincided with the two proline residues of the oxygen-dependent degradation domain (P402 and P564) that act as...

  12. KLF10, transforming growth factor-{beta}-inducible early gene 1, acts as a tumor suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki-Duk [Center for Agricultural Biomaterials, Seoul National University, Seoul 151-921 (Korea, Republic of); Laboratory of Protein Engineering and Comparative Immunology, School of Agricultural Biotechnology, Seoul National University, Seoul 151-921 (Korea, Republic of); Kim, Duk-Jung [The Institute of Hankook Life Science, 7-9 Myungryun-dong, Jongno-gu, Seoul 110-521 (Korea, Republic of); Lee, Jong Eun [Department of Anatomy, College of Medicine, Yonsei University, Seoul 120-752 (Korea, Republic of); Yun, Cheol-Heui [Center for Agricultural Biomaterials, Seoul National University, Seoul 151-921 (Korea, Republic of); Laboratory of Protein Engineering and Comparative Immunology, School of Agricultural Biotechnology, Seoul National University, Seoul 151-921 (Korea, Republic of); Lee, Woon Kyu, E-mail: wklee@inha.ac.kr [Laboratory of Developmental Genetics, School of Medicine, Inha University, Incheon 400-712 (Korea, Republic of); Brain Korea 21 Center for Advanced Medical Education, School of Medicine, Inha University, Incheon 400-712 (Korea, Republic of)

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer KLF10{sup -/-} mice exhibited accelerated papilloma development after DMBA/TPA treatment. Black-Right-Pointing-Pointer KLF10{sup -/-} keratinocytes showed increased proliferation and apoptosis. Black-Right-Pointing-Pointer KLF10{sup -/-} MEFs yielded more colonies than wild-type one with H-Ras transfection. Black-Right-Pointing-Pointer KLF10 dose-dependently activated p21{sup WAF1/CIP1} transcription. Black-Right-Pointing-Pointer KLF10 is a tumor suppressor and that it targets p21{sup WAF1/CIP1} transcription. -- Abstract: Krueppel-like factor 10 (KLF10) has been suggested to be a putative tumor suppressor. In the present study, we generated KLF10 deficient mice to explore this hypothesis in vivo. KLF10 deficient mice exhibited increased predisposition to skin tumorigenesis and markedly accelerated papilloma development after DMBA/TPA treatment. On the other hand, KLF10 deficient keratinocytes showed increased proliferation and apoptosis. In colony formation assays after oncogenic H-Ras transfection, KLF10 deficient mouse embryonic fibroblasts (MEFs) yielded more colonies than wild-type MEFs. Furthermore, KLF10 dose-dependently activated p21{sup WAF1/CIP1} transcription, which was independent of p53 and Sp1 binding sites in p21{sup WAF1/CIP1} promoter. This study demonstrates that KLF10 is a tumor suppressor and that it targets p21{sup WAF1/CIP1} transcription.

  13. The Ras effector RASSF2 is a novel tumor-suppressor gene in human colorectal cancer.

    Science.gov (United States)

    Akino, Kimishige; Toyota, Minoru; Suzuki, Hiromu; Mita, Hiroaki; Sasaki, Yasushi; Ohe-Toyota, Mutsumi; Issa, Jean-Pierre J; Hinoda, Yuji; Imai, Kohzoh; Tokino, Takashi

    2005-07-01

    Activation of Ras signaling is a hallmark of colorectal cancer (CRC), but the roles of negative regulators of Ras are not fully understood. Our aim was to address that question by surveying genetic and epigenetic alterations of Ras-Ras effector genes in CRC cells. The expression and methylation status of 6 RASSF family genes were examined using RT-PCR and bisulfite PCR in CRC cell lines and in primary CRCs and colorectal adenomas. Colony formation assays and flow cytometry were used to assess the tumor suppressor activities of RASSF1 and RASSF2. Immunofluorescence microscopy was used to determine the effect of altered RASSF2 expression on cell morphology. Mutations of K- ras , BRAF, and p53 were identified using single-strand conformation analysis and direct sequencing. Aberrant methylation and histone deacetylation of RASSF2 was associated with the gene's silencing in CRC. The activities of RASSF2, which were distinct from those of RASSF1, included induction of morphologic changes and apoptosis; moreover, its ability to prevent cell transformation suggests that RASSF2 acts as a tumor suppressor in CRC. Primary CRCs that showed K- ras /BRAF mutations also frequently showed RASSF2 methylation, and inactivation of RASSF2 enhanced K- ras -induced oncogenic transformation. RASSF2 methylation was also frequently identified in colorectal adenomas. RASSF2 is a novel tumor suppressor gene that regulates Ras signaling and plays a pivotal role in the early stages of colorectal tumorigenesis.

  14. 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

  15. Aggregation-primed molten globule conformers of the p53 core domain provide potential tools for studying p53C aggregation in cancer.

    Science.gov (United States)

    Pedrote, Murilo M; de Oliveira, Guilherme A P; Felix, Adriani L; Mota, Michelle F; Marques, Mayra de A; Soares, Iaci N; Iqbal, Anwar; Norberto, Douglas R; Gomes, Andre M O; Gratton, Enrico; Cino, Elio A; Silva, Jerson L

    2018-05-31

    The functionality of the tumor suppressor p53 is altered in more than 50% of human cancers, and many individuals with cancer exhibit amyloid-like buildups of aggregated p53. An understanding of what triggers the pathogenic amyloid conversion of p53 is required for the further development of cancer therapies. Here, perturbation of the p53 core domain (p53C) with sub-denaturing concentrations of guanidine hydrochloride and high hydrostatic pressure revealed native-like molten globule (MG) states, a subset of which were highly prone to amyloidogenic aggregation. We found that MG conformers of p53C, likely representing population-weighted averages of multiple states, have different volumetric properties, as determined by pressure perturbation and size-exclusion chromatography. We also found that they bind the fluorescent dye 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) and have a native-like tertiary structure that occludes the single Trp residue in p53. Fluorescence experiments revealed conformational changes of the single Trp and Tyr residues before p53 unfolding and the presence of MG conformers, some of which were highly prone to aggregation. P53C exhibited marginal unfolding cooperativity, which could be modulated from unfolding to aggregation pathways with chemical or physical forces. We conclude that trapping amyloid precursor states in solution is a promising approach for understanding p53 aggregation in cancer. Our findings support the use of single-Trp fluorescence as a probe for evaluating p53 stability, effects of mutations, and the efficacy of therapeutics designed to stabilize p53. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Andrographolide promotes vincristine-induced SK-NEP-1 tumor cell death via PI3K-AKT-p53 signaling pathway

    Directory of Open Access Journals (Sweden)

    Zhang M

    2016-09-01

    Full Text Available Mingsheng Zhang, Enda Xue, Wei Shao Department of Pediatric Surgery, Liaocheng People’s Hospital, Liaocheng, Shandong Province, People’s Republic of China Background: Nephroblastoma (Wilms’ tumor [WT] is the most common malignant renal cancer in children. Although the outcome of WT has significantly improved as a result of the combination of surgery, chemotherapy, and radiotherapy; in some cases WT results in severe complications. Thus, novel strategies that would decrease treatment burden are required. The aim of the current study was to investigate the synergistic antitumor effect of andrographolide (AND in combination with vincristine (VCR on WT cells.Methods: Cell Counting Kit-8 assay was used to investigate the synergistic antiproliferation effect of AND and/or VCR on SK-NEP-1 cells in vitro. Meanwhile, SK-NEP-1 xenografts were used to detect the antitumor effect in vivo. Apoptosis and autophagy were then detected by Annexin V, monodansylcadaverine staining. Finally, the underlying signaling transduction was determined with Western blotting.Results: The combination of AND with VCR significantly suppressed SK-NEP-1 cell proliferation in vitro and inhibited xenograft tumor growth in vivo, compared with AND or VCR treatment alone. In addition, the synergistic antitumor effect of AND on the cells was due to an increased apoptosis, not autophagy. Moreover, PI3K-AKT-p53 signaling pathway was involved in the process of combination treatment, which was confirmed when a selective AKT activator was applied.Conclusion: The combination of AND with VCR has a strong synergistic antitumor effect on WT via PI3K-AKT-p53 signaling pathway, thereby representing a potential treatment for WT in the near future. Keywords: andrographolide, vincristine, p53, drug combination

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

    Science.gov (United States)

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

    2016-01-01

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

  18. Different Recognition of DNA Modified by Antitumor Cisplatin and Its Clinically Ineffective trans Isomer by Tumor Suppressor Protein p53

    Czech Academy of Sciences Publication Activity Database

    Kašpárková, Jana; Pospíšilová, Š.; Brabec, Viktor

    2001-01-01

    Roč. 276, č. 19 (2001), s. 16064-16069 ISSN 0021-9258 R&D Projects: GA ČR GA305/99/0695; GA ČR GA305/01/0418; GA ČR GA301/00/P094; GA AV ČR IAA5004101; GA MZd NL6058 Grant - others:HHMI(US) 55000313; Wellcome Trust(GB) 062366/Z/00/Z Institutional research plan: CEZ:AV0Z5004920 Keywords : Interstrand cross-links * platinum complexes * supercoiled DNA Subject RIV: BO - Biophysics Impact factor: 7.258, year: 2001

  19. The tumor suppressor SHIP1 colocalizes in nucleolar cavities with p53 and components of PML nuclear bodies

    OpenAIRE

    Ehm, Patrick; Nalaskowski, Marcus M; Wundenberg, Torsten; Jücker, Manfred

    2015-01-01

    The inositol 5-phosphatase SHIP1 is a negative regulator of signaling processes in haematopoietic cells. By converting PI(3,4,5)P3 to PtdIns(3,4)P2 at the plasma membrane, SHIP1 modifies PI3-kinase mediated signaling. We have recently demonstrated that SHIP1 is a nucleo-cytoplasmic shuttling protein and SHIP1 nuclear puncta partially colocalize with FLASH, a component of nuclear bodies. In this study, we demonstrate that endogenous SHIP1 localizes to intranucleolar regions of both normal and ...

  20. The Quest for the 1p36 Tumor Suppressor

    Science.gov (United States)

    Bagchi, Anindya; Mills, Alea A.

    2010-01-01

    Genomic analyses of late-stage human cancers have uncovered deletions encompassing 1p36, thereby providing an extensive body of literature supporting the idea that a potent tumor suppressor resides in this interval. Although a number of genes have been proposed as 1p36 candidate tumor suppressors, convincing evidence that their encoded products protect from cancer has been scanty. A recent functional study identified CHD5 as a novel tumor suppressor mapping to 1p36. Here we discuss evidence supporting CHD5’s tumor suppressive role. Together, these findings suggest that strategies designed to enhance CHD5 activity could provide novel approaches for treating a broad range of human malignancies. PMID:18413720

  1. N-methylpurine DNA glycosylase inhibits p53-mediated cell cycle arrest and coordinates with p53 to determine sensitivity to alkylating agents.

    Science.gov (United States)

    Song, Shanshan; Xing, Guichun; Yuan, Lin; Wang, Jian; Wang, Shan; Yin, Yuxin; Tian, Chunyan; He, Fuchu; Zhang, Lingqiang

    2012-08-01

    Alkylating agents induce genome-wide base damage, which is repaired mainly by N-methylpurine DNA glycosylase (MPG). An elevated expression of MPG in certain types of tumor cells confers higher sensitivity to alkylation agents because MPG-induced apurinic/apyrimidic (AP) sites trigger more strand breaks. However, the determinant of drug sensitivity or insensitivity still remains unclear. Here, we report that the p53 status coordinates with MPG to play a pivotal role in such process. MPG expression is positive in breast, lung and colon cancers (38.7%, 43.4% and 25.3%, respectively) but negative in all adjacent normal tissues. MPG directly binds to the tumor suppressor p53 and represses p53 activity in unstressed cells. The overexpression of MPG reduced, whereas depletion of MPG increased, the expression levels of pro-arrest gene downstream of p53 including p21, 14-3-3σ and Gadd45 but not proapoptotic ones. The N-terminal region of MPG was specifically required for the interaction with the DNA binding domain of p53. Upon DNA alkylation stress, in p53 wild-type tumor cells, p53 dissociated from MPG and induced cell growth arrest. Then, AP sites were repaired efficiently, which led to insensitivity to alkylating agents. By contrast, in p53-mutated cells, the AP sites were repaired with low efficacy. To our knowledge, this is the first direct evidence to show that a DNA repair enzyme functions as a selective regulator of p53, and these findings provide new insights into the functional linkage between MPG and p53 in cancer therapy.

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

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  3. Andrographolide promotes vincristine-induced SK-NEP-1 tumor cell death via PI3K-AKT-p53 signaling pathway

    Science.gov (United States)

    Zhang, Mingsheng; Xue, Enda; Shao, Wei

    2016-01-01

    Background Nephroblastoma (Wilms’ tumor [WT]) is the most common malignant renal cancer in children. Although the outcome of WT has significantly improved as a result of the combination of surgery, chemotherapy, and radiotherapy; in some cases WT results in severe complications. Thus, novel strategies that would decrease treatment burden are required. The aim of the current study was to investigate the synergistic antitumor effect of andrographolide (AND) in combination with vincristine (VCR) on WT cells. Methods Cell Counting Kit-8 assay was used to investigate the synergistic antiproliferation effect of AND and/or VCR on SK-NEP-1 cells in vitro. Meanwhile, SK-NEP-1 xenografts were used to detect the antitumor effect in vivo. Apoptosis and autophagy were then detected by Annexin V, monodansylcadaverine staining. Finally, the underlying signaling transduction was determined with Western blotting. Results The combination of AND with VCR significantly suppressed SK-NEP-1 cell proliferation in vitro and inhibited xenograft tumor growth in vivo, compared with AND or VCR treatment alone. In addition, the synergistic antitumor effect of AND on the cells was due to an increased apoptosis, not autophagy. Moreover, PI3K-AKT-p53 signaling pathway was involved in the process of combination treatment, which was confirmed when a selective AKT activator was applied. Conclusion The combination of AND with VCR has a strong synergistic antitumor effect on WT via PI3K-AKT-p53 signaling pathway, thereby representing a potential treatment for WT in the near future. PMID:27729773

  4. The p53-mediated cytotoxicity of photodynamic therapy of cancer: Recent advances

    International Nuclear Information System (INIS)

    Zawacka-Pankau, Joanna; Krachulec, Justyna; Grulkowski, Ireneusz; Bielawski, Krzysztof P.; Selivanova, Galina

    2008-01-01

    Photodynamic therapy (PDT) is a promising modality for the treatment of both pre-malignant and malignant lesions. The mechanism of action converges mainly on the generation of reactive oxygen species which damage cancer cells directly as well as indirectly acting on tumor vasculature. The exact mechanism of PDT action is not fully understood, which is a formidable barrier to its successful clinical application. Elucidation of the mechanisms of cancer cell elimination by PDT might help in establishing highly specific, non-genotoxic anti-cancer treatment of tomorrow. One of the candidate PDT targets is the well-known tumor suppressor p53 protein recognized as the guardian of the genome. Together with its family members, p73 and p63 proteins, p53 is involved in apoptosis induction upon stress stimuli. The wild-type and mutant p53-targeting chemotherapeutics are currently extensively investigated as a promising strategy for highly specific anti-cancer therapy. In photodynamic therapy porphyrinogenic sensitizers are the most widely used compounds due to their potent biophysical and biochemical properties. Recent data suggest that the p53 tumor suppressor protein might play a significant role in porphyrin-PDT-mediated cell death by direct interaction with the drug which leads to its accumulation and induction of p53-dependent cell death both in the dark and upon irradiation. In this review we describe the available evidence on the role of p53 in PDT

  5. Survivin inhibits anti-growth effect of p53 activated by aurora B

    International Nuclear Information System (INIS)

    Jung, Ji-Eun; Kim, Tae-Kyung; Lee, Joong-Seob; Oh, Se-Yeong; Kwak, Sungwook; Jin, Xun; Sohn, Jin-Young; Song, Min-Keun; Sohn, Young-Woo; Lee, Soo-Yeon; Pian, Xumin; Lee, Jang-Bo; Chung, Yong Gu; Choi, Young Ki; You, Seungkwon; Kim, Hyunggee

    2005-01-01

    Genomic instability and apoptosis evasion are hallmarks of cancer, but the molecular mechanisms governing these processes remain elusive. Here, we found that survivin, a member of the apoptosis-inhibiting gene family, and aurora B kinase, a chromosomal passenger protein, were co-overexpressed in the various glioblastoma cell lines and tumors. Notably, exogenous introduction of the aurora B in human BJ cells was shown to decrease cell growth and increase the senescence-associated β-galactosidase activity by activation of p53 tumor suppressor. However, aurora B overexpression failed to inhibit cell proliferation in BJ and U87MG cells transduced with dominant-negative p53 as well as in p53 -/- mouse astrocytes. Aurora B was shown to increase centrosome amplification in the p53 -/- astrocytes. Survivin was shown to induce anchorage-independent growth and inhibit anti-proliferation and drug-sensitive apoptosis caused by aurora B. Overexpression of both survivin and aurora B further accelerated the proliferation of BJ cells. Taken together, the present study indicates that survivin should accelerate tumorigenesis by inhibiting the anti-proliferative effect of p53 tumor suppressor that is activated by aurora B in normal and glioblastoma cells containing intact p53

  6. RET is a potential tumor suppressor gene in colorectal cancer

    Science.gov (United States)

    Luo, Yanxin; Tsuchiya, Karen D.; Park, Dong Il; Fausel, Rebecca; Kanngurn, Samornmas; Welcsh, Piri; Dzieciatkowski, Slavomir; Wang, Jianping; Grady, William M.

    2012-01-01

    Cancer arises as the consequence of mutations and epigenetic alterations that activate oncogenes and inactivate tumor suppressor genes. Through a genome-wide screen for methylated genes in colon neoplasms, we identified aberrantly methylated RET in colorectal cancer. RET, a transmembrane receptor tyrosine kinase and a receptor for the GDNF-family ligands, was one of the first oncogenes to be identified and has been shown to be an oncogene in thyroid cancer and pheochromocytoma. However, unexpectedly, we found RET is methylated in 27% of colon adenomas and in 63% of colorectal cancers, and now provide evidence that RET has tumor suppressor activity in colon cancer. The aberrant methylation of RET correlates with decreased RET expression, whereas the restoration of RET in colorectal cancer cell lines results in apoptosis. Furthermore, in support of a tumor suppressor function of RET, mutant RET has also been found in primary colorectal cancer. We now show that these mutations inactivate RET, which is consistent with RET being a tumor suppressor gene in the colon. These findings suggest that the aberrant methylation of RET and the mutational inactivation of RET promote colorectal cancer formation and that RET can serve as a tumor suppressor gene in the colon. Moreover, the increased frequency of methylated RET in colon cancers compared to adenomas suggests RET inactivation is involved in the progression of colon adenomas to cancer. PMID:22751117

  7. Prognostic value of tumor suppressors in osteosarcoma before and after neoadjuvant chemotherapy.

    Science.gov (United States)

    Robl, Bernhard; Pauli, Chantal; Botter, Sander Martijn; Bode-Lesniewska, Beata; Fuchs, Bruno

    2015-05-09

    Primary bone cancers are among the deadliest cancer types in adolescents, with osteosarcomas being the most prevalent form. Osteosarcomas are commonly treated with multi-drug neoadjuvant chemotherapy and therapy success as well as patient survival is affected by the presence of tumor suppressors. In order to assess the prognostic value of tumor-suppressive biomarkers, primary osteosarcoma tissues were analyzed prior to and after neoadjuvant chemotherapy. We constructed a tissue microarray from high grade osteosarcoma samples, consisting of 48 chemotherapy naïve biopsies (BXs) and 47 tumor resections (RXs) after neoadjuvant chemotherapy. We performed immunohistochemical stainings of P53, P16, maspin, PTEN, BMI1 and Ki67, characterized the subcellular localization and related staining outcome with chemotherapy response and overall survival. Binary logistic regression analysis was used to analyze chemotherapy response and Kaplan-Meier-analysis as well as the Cox proportional hazards model was applied for analysis of patient survival. No significant associations between biomarker expression in BXs and patient survival or chemotherapy response were detected. In univariate analysis, positive immunohistochemistry of P53 (P = 0.008) and P16 (P16; P = 0.033) in RXs was significantly associated with poor survival prognosis. In addition, presence of P16 in RXs was associated with poor survival in multivariate regression analysis (P = 0.003; HR = 0.067) while absence of P16 was associated with good chemotherapy response (P = 0.004; OR = 74.076). Presence of PTEN on tumor RXs was significantly associated with an improved survival prognosis (P = 0.022). Positive immunohistochemistry (IHC) of P16 and P53 in RXs was indicative for poor overall patient survival whereas positive IHC of PTEN was prognostic for good overall patient survival. In addition, we found that P16 might be a marker of osteosarcoma chemotherapy resistance. Therefore, our study supports the use of tumor RXs to

  8. Mutant, wild type, or overall p53 expression: freedom from clinical progression in tumours of astrocytic lineage.

    Science.gov (United States)

    Pardo, F S; Hsu, D W; Zeheb, R; Efird, J T; Okunieff, P G; Malkin, D M

    2004-11-01

    Abnormalities of the p53 tumor-suppressor gene are found in a significant proportion of astrocytic brain tumours. We studied tumour specimens from 74 patients evaluated over 20 years at the Massachusetts General Hospital, where clinical outcome could be determined and sufficient pathologic material was available for immunostaining. p53 expression studies employed an affinity-purified p53 monoclonal antibody, whose specificity was verified in absorption studies and, in a minority of cases, a second antibody recognising a different epitope of p53. Significant overexpression of p53 protein was found in 48% of the 74 tumours included in this series and high levels of expression were associated with higher mortality from astrocytic tumours (Pexpression of p53 plays an important role in the pathobiology of these tumours. In a subset of 36 cases, coding regions of the p53 gene were completely sequenced via SSCP and direct DNA sequencing, revealing that overexpression of p53 protein is not always associated with point mutations in conserved exons of the p53 gene. Finally, we confirmed p53 protein expression in early-passage human glioma cell lines of known p53 mutational status and immunostaining scores. Although grade continues to be the strongest prognostic variable, the use of p53 staining as a prognostic indicator, in contrast to mutational DNA analyses, may be a useful adjunct in identifying patients at higher risk of treatment failure.

  9. Therapeutic targeting of the p53 pathway in cancer stem cells

    Science.gov (United States)

    Prabhu, Varun V.; Allen, Joshua E.; Hong, Bo; Zhang, Shengliang; Cheng, Hairong; El-Deiry, Wafik S.

    2013-01-01

    Introduction Cancer stem cells are a high profile drug target for cancer therapeutics due to their indispensable role in cancer progression, maintenance, and therapeutic resistance. Restoring wild-type p53 function is an attractive new therapeutic approach for the treatment of cancer due to the well-described powerful tumor suppressor function of p53. As emerging evidence intimately links p53 and stem cell biology, this approach also provides an opportunity to target cancer stem cells. Areas covered Therapeutic approaches to restore the function of wild-type p53, cancer and normal stem cell biology in relation to p53, and the downstream effects of p53 on cancer stem cells. Expert opinion The restoration of wild-type p53 function by targeting p53 directly, its interacting proteins, or its family members holds promise as a new class of cancer therapies. This review examines the impact that such therapies may have on normal and cancer stem cells based on the current evidence linking p53 signaling with these populations. PMID:22998602

  10. Nuclear localization signal of ING4 plays a key role in its binding to p53

    International Nuclear Information System (INIS)

    Zhang Xin; Wang Kesheng; Wang Zhiqin; Xu Lusheng; Wang Qingwan; Chen Fei; Wei Dongzhi; Han Zeguang

    2005-01-01

    ING4, a novel member of ING family, is recently reported to interact with tumor suppressor p53 and negatively regulate the cell growth with significant G2/M arrest of cell cycle in HepG2 cells through upregulation of p53-inducible gene p21. However, which region of ING4 could have contributed to the binding to p53 remains largely unclear. Herein, the GST-pulldown experiments revealed that the middle region of ING4, a potential bipartite nuclear localization signal (NLS), could be involved in the binding to p53. Furthermore, the interaction of ING4 to p53 was abrogated in vitro and in vivo when certain mutations or the entire deletion of the NLS domain occurred. More interestingly, the mutations of the NLS domain could alter the ING4 nuclear localization, disrupt the interaction of ING4 with p53, and even, deregulate the p53-inducible gene p21 in MCF-7 cells. All data indicated that the NLS domain of ING4 is essential for the binding of ING4 to p53 and the function of ING4 associated with p53

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

    International Nuclear Information System (INIS)

    Chen Chen; Shimizu, Shigeomi; Tsujimoto, Yoshihide; Motoyama, Noboru

    2005-01-01

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

  12. p53 Maintains Genomic Stability by Preventing Interference between Transcription and Replication

    Directory of Open Access Journals (Sweden)

    Constance Qiao Xin Yeo

    2016-04-01

    Full Text Available p53 tumor suppressor maintains genomic stability, typically acting through cell-cycle arrest, senescence, and apoptosis. We discovered a function of p53 in preventing conflicts between transcription and replication, independent of its canonical roles. p53 deficiency sensitizes cells to Topoisomerase (Topo II inhibitors, resulting in DNA damage arising spontaneously during replication. Topoisomerase IIα (TOP2A-DNA complexes preferentially accumulate in isogenic p53 mutant or knockout cells, reflecting an increased recruitment of TOP2A to regulate DNA topology. We propose that p53 acts to prevent DNA topological stress originating from transcription during the S phase and, therefore, promotes normal replication fork progression. Consequently, replication fork progression is impaired in the absence of p53, which is reversed by transcription inhibition. Pharmacologic inhibition of transcription also attenuates DNA damage and decreases Topo-II-DNA complexes, restoring cell viability in p53-deficient cells. Together, our results demonstrate a function of p53 that may underlie its role in tumor suppression.

  13. Conformational detection of p53's oligomeric state by FlAsH Fluorescence.

    Science.gov (United States)

    Webber, Tawnya M; Allen, Andrew C; Ma, Wai Kit; Molloy, Rhett G; Kettelkamp, Charisse N; Dow, Caitlin A; Gage, Matthew J

    2009-06-19

    The p53 tumor suppressor protein is a critical checkpoint in prevention of tumor formation, and the function of p53 is dependent on proper formation of the active tetramer. In vitro studies have shown that p53 binds DNA most efficiently as a tetramer, though inactive p53 is predicted to be monomeric in vivo. We demonstrate that FlAsH binding can be used to distinguish between oligomeric states of p53, providing a potential tool to explore p53 oligomerization in vivo. The FlAsH tetra-cysteine binding motif has been incorporated along the dimer and tetramer interfaces in the p53 tetramerization domain to create reporters for the dimeric and tetrameric states of p53, though the geometry of the four cysteines is critical for efficient FlAsH binding. Furthermore, we demonstrate that FlAsH binding can be used to monitor tetramer formation in real-time. These results demonstrate the potential for using FlAsH fluorescence to monitor protein-protein interactions in vivo.

  14. Evaluation of potential prognostic value of Bmi-1 gene product and selected markers of proliferation (Ki-67 and apoptosis (p53 in the neuroblastoma group of tumors

    Directory of Open Access Journals (Sweden)

    Katarzyna Taran

    2016-02-01

    Full Text Available Introduction: Cancer in children is a very important issue in pediatrics. The least satisfactory treatment outcome occurs among patients with clinically advanced neuroblastomas. Despite much research, the biology of this tumor still remains unclear, and new prognostic factors are sought. The Bmi-1 gene product is a currently highly investigated protein which belongs to the Polycomb group (PcG and has been identified as a regulator of primary neural crest cells. It is believed that Bmi‑1 and N-myc act together and are both involved in the pathogenesis of neuroblastoma. The aim of the study was to assess the potential prognostic value of Bmi-1 protein and its relations with mechanisms of proliferation and apoptosis in the neuroblastoma group of tumors.Material/Methods: 29 formalin-fixed and paraffin-embedded neuroblastoma tissue sections were examined using mouse monoclonal antibodies anti-Bmi-1, anti-p53 and anti-Ki-67 according to the manufacturer’s instructions.Results: There were found statistically significant correlations between Bmi-1 expression and tumor histology and age of patients.Conclusions: Bmi-1 seems to be a promising marker in the neuroblastoma group of tumors whose expression correlates with widely accepted prognostic parameters. The pattern of BMI-1 expression may indicate that the examined protein is also involved in maturation processes in tumor tissue.

  15. Brca1/p53 deficient mouse breast tumor hemodynamics during hyperoxic respiratory challenge monitored by a novel wide-field functional imaging (WiFI) system

    Science.gov (United States)

    Moy, Austin; Kim, Jae G.; Lee, Eva Y. H. P.; Tromberg, Bruce; Cerussi, Albert; Choi, Bernard

    2009-02-01

    Current imaging modalities allow precise visualization of tumors but do not enable quantitative characterization of the tumor metabolic state. Such quantitative information would enhance our understanding of tumor progression and response to treatment, and to our overall understanding of tumor biology. To address this problem, we have developed a wide-field functional imaging (WiFI) instrument which combines two optical imaging modalities, spatially modulated imaging (MI) and laser speckle imaging (LSI). Our current WiFI imaging protocol consists of multispectral imaging in the near infrared (650-980 nm) spectrum, over a wide (7 cm × 5 cm) field of view. Using MI, the spatially-resolved reflectance of sinusoidal patterns projected onto the tissue is assessed, and optical properties of the tissue are estimated using a Monte Carlo model. From the spatial maps of local absorption and reduced scattering coefficients, tissue composition information is extracted in the form of oxy-, deoxy-, and total hemoglobin concentrations, and percentage of lipid and water. Using LSI, the reflectance of a 785 nm laser speckle pattern on the tissue is acquired and analyzed to compute maps of blood perfusion in the tissue. Tissue metabolism state is estimated from the values of blood perfusion, volume and oxygenation state. We currently are employing the WiFI instrument to study tumor development in a BRCA1/p53 deficient mice breast tumor model. The animals are monitored with WiFI during hyperoxic respiratory challenge. At present, four tumors have been measured with WiFI, and preliminary data suggest that tumor metabolic changes during hyperoxic respiratory challenge can be determined.

  16. COX-2 and p53 in human sinonasal cancer

    DEFF Research Database (Denmark)

    Holmila, Reetta; Cyr, Diane; Luce, Danièle

    2008-01-01

    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...... to development of cancer. Many signals that activate COX-2 also induce tumor suppressor p53, a transcription factor central in cellular stress response. We investigated COX-2 and p53 expressions by immunohistochemistry in 50 SNCs (23 adenocarcinomas, and 27 squamous cell carcinomas (SCC); 48 analyzed for COX-2...... displayed adenocarcinoma. COX-2 was expressed at higher levels in adenocarcinoma as compared to SSC (p COX-2 expression showed significant association with occupational exposure to wood dust (p = 0.024), and with nonsmoking status (p = 0.001). No statistically significant associations between...

  17. Inactivation and inducible oncogenic mutation of p53 in gene targeted pigs.

    Directory of Open Access Journals (Sweden)

    Simon Leuchs

    Full Text Available Mutation of the tumor suppressor p53 plays a major role in human carcinogenesis. Here we describe gene-targeted porcine mesenchymal stem cells (MSCs and live pigs carrying a latent TP53(R167H mutant allele, orthologous to oncogenic human mutant TP53(R175H and mouse Trp53(R172H, that can be activated by Cre recombination. MSCs carrying the latent TP53(R167H mutant allele were analyzed in vitro. Homozygous cells were p53 deficient, and on continued culture exhibited more rapid proliferation, anchorage independent growth, and resistance to the apoptosis-inducing chemotherapeutic drug doxorubicin, all characteristic of cellular transformation. Cre mediated recombination activated the latent TP53(R167H allele as predicted, and in homozygous cells expressed mutant p53-R167H protein at a level ten-fold greater than wild-type MSCs, consistent with the elevated levels found in human cancer cells. Gene targeted MSCs were used for nuclear transfer and fifteen viable piglets were produced carrying the latent TP53(R167H mutant allele in heterozygous form. These animals will allow study of p53 deficiency and expression of mutant p53-R167H to model human germline, or spontaneous somatic p53 mutation. This work represents the first inactivation and mutation of the gatekeeper tumor suppressor gene TP53 in a non-rodent mammal.

  18. Inhibitor of differentiation 4 (Id4) is a potential tumor suppressor in prostate cancer

    International Nuclear Information System (INIS)

    Carey, Jason PW; Asirvatham, Ananthi J; Galm, Oliver; Ghogomu, Tandeih A; Chaudhary, Jaideep

    2009-01-01

    Inhibitor of differentiation 4 (Id4), a member of the Id gene family is also a dominant negative regulator of basic helix loop helix (bHLH) transcription factors. Some of the functions of Id4 appear to be unique as compared to its other family members Id1, Id2 and Id3. Loss of Id4 gene expression in many cancers in association with promoter hypermethylation has led to the proposal that Id4 may act as a tumor suppressor. In this study we provide functional evidence that Id4 indeed acts as a tumor suppressor and is part of a cancer associated epigenetic re-programming. Data mining was used to demonstrate Id4 expression in prostate cancer. Methylation specific polymerase chain reaction (MSP) analysis was performed to understand molecular mechanisms associated with Id4 expression in prostate cancer cell lines. The effect of ectopic Id4 expression in DU145 cells was determined by cell cycle analysis (3H thymidine incorporation and FACS), expression of androgen receptor, p53 and cyclin dependent kinase inhibitors p27 and p21 by a combination of RT-PCR, real time-PCR, western blot and immuno-cytochemical analysis. Id4 expression was down-regulated in prostate cancer. Id4 expression was also down-regulated in prostate cancer line DU145 due to promoter hyper-methylation. Ectopic Id4 expression in DU145 prostate cancer cell line led to increased apoptosis and decreased cell proliferation due in part by an S-phase arrest. In addition to S-phase arrest, ectopic Id4 expression in PC3 cells also resulted in prolonged G2/M phase. At the molecular level these changes were associated with increased androgen receptor (AR), p21, p27 and p53 expression in DU145 cells. The results suggest that Id4 acts directly as a tumor suppressor by influencing a hierarchy of cellular processes at multiple levels that leads to a decreased cell proliferation and change in morphology that is possibly mediated through induction of previously silenced tumor suppressors

  19. Inhibitor of differentiation 4 (Id4 is a potential tumor suppressor in prostate cancer

    Directory of Open Access Journals (Sweden)

    Carey Jason PW

    2009-06-01

    Full Text Available Abstract Background Inhibitor of differentiation 4 (Id4, a member of the Id gene family is also a dominant negative regulator of basic helix loop helix (bHLH transcription factors. Some of the functions of Id4 appear to be unique as compared to its other family members Id1, Id2 and Id3. Loss of Id4 gene expression in many cancers in association with promoter hypermethylation has led to the proposal that Id4 may act as a tumor suppressor. In this study we provide functional evidence that Id4 indeed acts as a tumor suppressor and is part of a cancer associated epigenetic re-programming. Methods Data mining was used to demonstrate Id4 expression in prostate cancer. Methylation specific polymerase chain reaction (MSP analysis was performed to understand molecular mechanisms associated with Id4 expression in prostate cancer cell lines. The effect of ectopic Id4 expression in DU145 cells was determined by cell cycle analysis (3H thymidine incorporation and FACS, expression of androgen receptor, p53 and cyclin dependent kinase inhibitors p27 and p21 by a combination of RT-PCR, real time-PCR, western blot and immuno-cytochemical analysis. Results Id4 expression was down-regulated in prostate cancer. Id4 expression was also down-regulated in prostate cancer line DU145 due to promoter hyper-methylation. Ectopic Id4 expression in DU145 prostate cancer cell line led to increased apoptosis and decreased cell proliferation due in part by an S-phase arrest. In addition to S-phase arrest, ectopic Id4 expression in PC3 cells also resulted in prolonged G2/M phase. At the molecular level these changes were associated with increased androgen receptor (AR, p21, p27 and p53 expression in DU145 cells. Conclusion The results suggest that Id4 acts directly as a tumor suppressor by influencing a hierarchy of cellular processes at multiple levels that leads to a decreased cell proliferation and change in morphology that is possibly mediated through induction of previously

  20. p53 Protein interacts specifically with the meiosis-specific mammalian RecA-like protein DMC1 in meiosis.

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    Habu, Toshiyuki; Wakabayashi, Nobunao; Yoshida, Kayo; Yomogida, Kenntaro; Nishimune, Yoshitake; Morita, Takashi

    2004-06-01

    The tumor suppressor protein p53 is specifically expressed during meiosis in spermatocytes. Subsets of p53 knockout mice exhibit testicular giant cell degenerative syndrome, which suggests p53 may be associated with meiotic cell cycle and/or DNA metabolism. Here, we show that p53 binds to the mouse meiosis-specific RecA-like protein Mus musculus DMC1 (MmDMC1). The C-terminal domain (amino acid 234-340) of MmDMC1 binds to DNA-binding domain of p53 protein. p53 might be involved in homologous recombination and/or checkpoint function by directly binding to DMC1 protein to repress genomic instability in meiotic germ cells.

  1. Anti-tumor effect of cisplatin in human oral squamous cell carcinoma was enhanced by andrographolide via upregulation of phospho-p53 in vitro and in vivo.

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    Chen, Songjie; Hu, Hui; Miao, Shushu; Zheng, Jiayong; Xie, Zhijian; Zhao, Hui

    2017-05-01

    Oral squamous cell carcinoma is one of the most common neoplasm in the world. Despite the improvements in diagnosis and treatment, the outcome is still poor now. Thus, the development of novel therapeuticapproaches is needed. The aim of this study is to assess the synergistic anti-tumor effect of andrographolide with cisplatin (DDP) in oral squamous cell carcinoma CAL-27 cells in vitro and in vivo. We performed Cell Counting Kit-8 proliferation assay, apoptosis assay, and western blotting on CAL-27 cells treated with andrographolide, DDP or the combination in vitro. In vivo, we also treated CAL-27 xenografts with andrographolide or the combination, and performed terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay and immunohistochemical analysis of Ki-67. The results showed the combination of andrographolide and DDP synergistically inhibited CAL-27 cell proliferation in vitro and caused tumor regression in vivo in the CAL-27 xenografts. In addition, the synergistic anti-tumor effect of andrographolide with synergistic was due to an enhanced apoptosis. Moreover, the combination therapy upregulated the expression level of p-p53 in vitro and decreased Ki-67 expression in vivo. Our data indicate that the combination treatment of andrographolide and DDP results in synergistic anti-tumor growth activity against oral squamous cell carcinoma CAL-27 in vitro and in vivo. These results demonstrated that combination of andrographolide with DDP was likely to represent a potential therapeutic strategy for oral squamous cell carcinoma.

  2. Analysis of the expression level and methylation of tumor protein p53, phosphatase and tensin homolog and mutS homolog 2 in N-methyl-N-nitrosourea-induced thymic lymphoma in C57BL/6 mice.

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    Huo, Xueyun; Li, Zhenkun; Zhang, Shuangyue; Li, Changlong; Guo, Meng; Lu, Jing; Lv, Jianyi; Du, Xiaoyan; Chen, Zhenwen

    2017-10-01

    Tumorigenesis is often caused by somatic mutation or epigenetic changes in genes that regulate aspects of cell death, proliferation and survival. Although the functions of multiple tumor suppressor genes have been well studied in isolation, how these genes cooperate during the progression of a single tumor remains unclear in numerous cases. The present study used N-methyl-N-nitrosourea (MNU), one of the most potent mutagenic nitrosourea compounds, to induce thymic lymphoma in C57BL/6J mice. Subsequently, the protein expression levels of phosphatase and tensin homolog (PTEN), transformation protein 53 and mutS homolog 2 (MSH2) were evaluated concomitantly in the thymus, liver, kidney and spleen of MNU-treated mice by western blotting. To determine whether changes in expression level were due to aberrant epigenetic regulation, the present study further examined the methylation status of each gene by MassARRAY analysis. During the tumorigenesis process of an MNU-induced single thymic lymphoma, the expression level of PTEN was revealed to be reduced in thymic lymphoma samples but not in normal or non-tumor thymus tissue samples. Furthermore, a marked reduction of P53 expression levels were demonstrated in thymic lymphomas and spleens with a metastatic tumor. Conversely, MSH2 upregulation was identified only in liver, kidney, and spleen samples that were infiltrated by thymic lymphoma cells. Furthermore, the present study revealed that a number of 5'-C-phosphate-G-3' sites located in the promoter of aberrantly expressed genes had significantly altered methylation statuses. These results improve the understanding of the course of mutagen-induced cancer, and highlight that epigenetic regulation may serve an important function in cancer.

  3. Dendrobium chrysanthum ethanolic extract induces apoptosis via p53 up-regulation in HeLa cells and inhibits tumor progression in mice.

    Science.gov (United States)

    Prasad, Ritika; Rana, Nishant Kumar; Koch, Biplob

    2017-06-01

    Background Dendrobium is one of the diverse genus of orchid plants. It possesses a number of pharmacological activities and has long been used in traditional system of medicine. The goal of this study was to investigate the apoptosis inducing property of the ethanolic extract from the leaves of Dendrobium chrysanthum, a species of Dendrobium whose anticancer role has not been ascertained yet. Methods To evaluate the anticancer activity of the ethanolic extract of D. chrysanthum in vitro in HeLa (human cervical cancer) cells, cytotoxic activity, generation of reactive oxygen species (ROS), induction of apoptosis and effect on cell cycle were determined. The in vivo study was carried out in Dalton's lymphoma (DL) bearing mice to assess the tumor growth delay. Results Our study demonstrated that the ethanolic extract showed dose-dependent cytotoxicity against HeLa cells. The extract exhibited dose-dependent increase in ROS production as well as apoptotic cell death which was further confirmed through presence of DNA fragmentation. Cell cycle analysis by flow cytometry suggests that the ethanolic extract perturbed cell cycle progression and leads to the delay of the cells in S phase. Further, the real-time PCR studies also showed up-regulation of apoptotic genes p53 and Bax. The in vivo antitumor activity exhibited significant increase in the life span of DL bearing mice as compared to control with significant decrease in abdominal size along with reduced tumor ascites. Conclusions These observations demonstrate the anticancer potential of the D. chrysanthum ethanolic extract mediated through p53-dependent apoptosis.

  4. Superior anti-tumor activity of the MDM2 antagonist idasanutlin and the Bcl-2 inhibitor venetoclax in p53 wild-type acute myeloid leukemia models

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    Christian Lehmann

    2016-06-01

    Full Text Available Abstract Background Venetoclax, a small molecule BH3 mimetic which inhibits the anti-apoptotic protein Bcl-2, and idasanutlin, a selective MDM2 antagonist, have both shown activity as single-agent treatments in pre-clinical and clinical studies in acute myeloid leukemia (AML. In this study, we deliver the rationale and molecular basis for the combination of idasanutlin and venetoclax for treatment of p53 wild-type AML. Methods The effect of idasanutlin and venetoclax combination on cell viability, apoptosis, and cell cycle progression was investigated in vitro using established AML cell lines. In vivo efficacy was demonstrated in subcutaneous and orthotopic xenograft models generated in female nude or non-obese diabetic/severe combined immunodeficiency (NOD/SCID mice. Mode-of-action analyses were performed by means of cell cycle kinetic studies, RNA sequencing as well as western blotting experiments. Results Combination treatment with venetoclax and idasanutlin results in synergistic anti-tumor activity compared with the respective single-agent treatments in vitro, in p53 wild-type AML cell lines, and leads to strongly superior efficacy in vivo, in subcutaneous and orthotopic AML models. The inhibitory effects of idasanutlin were cell-cycle dependent, with cells arresting in G1 in consecutive cycles and the induction of apoptosis only evident after cells had gone through at least two cell cycles. Combination treatment with venetoclax removed this dependency, resulting in an acceleration of cell death kinetics. As expected, gene expression studies using RNA sequencing showed significant alterations to pathways associated with p53 signaling and cell cycle arrest (CCND1 pathway in response to idasanutlin treatment. Only few gene expression changes were observed for venetoclax treatment and combination treatment, indicating that their effects are mediated mainly at the post-transcriptional level. Protein expression studies demonstrated that

  5. Translational Control Protein 80 Stimulates IRES-Mediated Translation of p53 mRNA in Response to DNA Damage

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    Marie-Jo Halaby

    2015-01-01

    Full Text Available Synthesis of the p53 tumor suppressor increases following DNA damage. This increase and subsequent activation of p53 are essential for the protection of normal cells against tumorigenesis. We previously discovered an internal ribosome entry site (IRES that is located at the 5′-untranslated region (UTR of p53 mRNA and found that the IRES activity increases following DNA damage. However, the mechanism underlying IRES-mediated p53 translation in response to DNA damage is still poorly understood. In this study, we discovered that translational control protein 80 (TCP80 has increased binding to the p53 mRNA in vivo following DNA damage. Overexpression of TCP80 also leads to increased p53 IRES activity in response to DNA damage. TCP80 has increased association with RNA helicase A (RHA following DNA damage and overexpression of TCP80, along with RHA, leads to enhanced expression of p53. Moreover, we found that MCF-7 breast cancer cells with decreased expression of TCP80 and RHA exhibit defective p53 induction following DNA damage and diminished expression of its downstream target PUMA, a proapoptotic protein. Taken together, our discovery of the function of TCP80 and RHA in regulating p53 IRES and p53 induction following DNA damage provides a better understanding of the mechanisms that regulate IRES-mediated p53 translation in response to genotoxic stress.

  6. Nongenotoxic p53 activation protects cells against S-phase-specific chemotherapy

    DEFF Research Database (Denmark)

    Kranz, Dominique; Dobbelstein, Matthias

    2006-01-01

    Mutations in the tumor suppressor gene TP53 represent the most frequent genetic difference between tumor cells and normal cells. Here, we have attempted to turn this difference into an advantage for normal cells during therapy. Using the Mdm2 antagonist nutlin-3, we first activated p53 in U2OS an...... a killer to a protector of cells, with the potential to reduce unwanted side effects of chemotherapy....

  7. Rescue of p53 function by small-molecule RITA in cervical carcinoma by blocking E6-mediated degradation.

    Science.gov (United States)

    Zhao, Carolyn Ying; Szekely, Laszlo; Bao, Wenjie; Selivanova, Galina

    2010-04-15

    Proteasomal degradation of p53 by human papilloma virus (HPV) E6 oncoprotein plays a pivotal role in the survival of cervical carcinoma cells. Abrogation of HPV-E6-dependent p53 destruction can therefore be a good strategy to combat cervical carcinomas. Here, we show that a small-molecule reactivation of p53 and induction of tumor cell apoptosis (RITA) is able to induce the accumulation of p53 and rescue its tumor suppressor function in cells containing high-risk HPV16 and HPV18 by inhibiting HPV-E6-mediated proteasomal degradation. RITA blocks p53 ubiquitination by preventing p53 interaction with E6-associated protein, required for HPV-E6-mediated degradation. RITA activates the transcription of proapoptotic p53 targets Noxa, PUMA, and BAX, and repressed the expression of pro-proliferative factors CyclinB1, CDC2, and CDC25C, resulting in p53-dependent apoptosis and cell cycle arrest. Importantly, RITA showed substantial suppression of cervical carcinoma xenografts in vivo. These results provide a proof of principle for the treatment of cervical cancer in a p53-dependent manner by using small molecules that target p53. (c)2010 AACR.

  8. The Regulation of Tumor Suppressor p63 by the Ubiquitin-Proteasome System

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    Stephen R. Armstrong

    2016-12-01

    Full Text Available The protein p63 has been identified as a homolog of the tumor suppressor protein p53 and is capable of inducing apoptosis, cell cycle arrest, or senescence. p63 has at least six isoforms, which can be divided into two major groups: the TAp63 variants that contain the N-terminal transactivation domain and the ΔNp63 variants that lack the N-terminal transactivation domain. The TAp63 variants are generally considered to be tumor suppressors involved in activating apoptosis and suppressing metastasis. ΔNp63 variants cannot induce apoptosis but can act as dominant negative inhibitors to block the function of TAp53, TAp73, and TAp63. p63 is rarely mutated in human tumors and is predominately regulated at the post-translational level by phosphorylation and ubiquitination. This review focuses primarily on regulation of p63 by the ubiquitin E-3 ligase family of enzymes via ubiquitination and proteasome-mediated degradation, and introduces a new key regulator of the p63 protein.

  9. Abnormal P-53 suppressor gene expression predicts for a poorer outcome in patients with locally advanced adenocarcinoma of the prostate treated by external beam radiation therapy with or without pre-radiation androgen ablation: results based on RTOG study 86-10

    International Nuclear Information System (INIS)

    Lawton, Colleen A.; Grignon, David; Caplan, Richard; Sarkar, Fazlul; Forman, Jeffrey; Mesic, John; Fu, Karen K.; Abrams, Ross

    1995-01-01

    Purpose/Objective: The purpose of this study is to establish the effect of the abnormal expression of the P-53 suppressor gene on the results of locally advanced adenocarcinoma of the prostate treated with radiation therapy with or without pre-radiation therapy androgen ablation. Materials and Methods: Patients evaluated were part of a RTOG phase III multi-institutional trial. This trial assessed the value of pre-radiation therapy androgen ablation on patients with locally advanced disease (bulky stage B and stage C). Of the 471 patients registered, pre-treatment pathological material was available for 129 patients. P-53 status was determined immunohistochemically utilizing a commercially available antibody (D07). Clinical endpoints evaluated were overall survival and development of metastases. Results: Twenty-three of the 129 patients had abnormal expression of the P-53 suppressor gene. Presence of this abnormal expression significantly correlated with lower overall survival (p=0.03) and the development of distant metastases (p=0.03). Abnormal expression of the P-53 gene was an independent prognostic indicator when evaluated against clinical stage and Gleason score. Conclusion: This data from patients entered on a phase III multi-institutional, randomized clinical trial shows that abnormal P-53 suppressor gene expression as determined immunohistochemically is an independent predictor of poorer survival and the development of distant metastases in patients with locally advanced adenocarcinoma of the prostate treated with radiation therapy with or without pre-radiation therapy androgen ablation

  10. Recent progress of the study of p53 control mechanism by ionizing radiation

    International Nuclear Information System (INIS)

    Kawai, Hidehiko

    2004-01-01

    Reviewed are the recent findings on the control mechanism of function and activity of p53 as a response factor to stress of ionizing radiation. The p53 protein is controlled to be essentially inactive in cells under normal conditions and is activated by various stresses. The role of p53 as a stress-responding and tumor-suppressing factor in cells with damaged DNA is discussed in relation with its participation in G1/S and G2/M checkpoints, DNA repair, and apoptosis. The stress like radiation affects the control mechanisms of stability and function of p53 through modification of its N-terminal region (the activation domain of transcription), DNA binding region (core domain) and C-terminal region (domains of the nuclear export signaling, tetramer formation and its own regulation). MDM2 (mouse double minute 2) family, the most important regulatory factor of p53, forms a negative feedback cycle since the family is the target factor of p53 transcription and also suppressor of p53. MDM2 is regulated by phosphorylation and by interaction with itself or other factors like p300/CBP. Further studies on p53 are thus important in various fields as well as in radiation biology. (N.I.)

  11. FATS is a transcriptional target of p53 and associated with antitumor activity

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    Zhang Xifeng

    2010-09-01

    Full Text Available Abstract Frequent mutations of p53 in human cancers exemplify its crucial role as a tumor suppressor transcription factor, and p21, a transcriptional target of p53, plays a central role in surveillance of cell-cycle checkpoints. Our previous study has shown that FATS stabilize p21 to preserve genome integrity. In this study we identified a novel transcript variant of FATS (GenBank: GQ499374 through screening a cDNA library from mouse testis, which uncovered the promoter region of mouse FATS. Mouse FATS was highly expressed in testis. The p53-responsive elements existed in proximal region of both mouse and human FATS promoters. Functional study indicated that the transcription of FATS gene was activated by p53, whereas such effect was abolished by site-directed mutagenesis in the p53-RE of FATS promoter. Furthermore, the expression of FATS increased upon DNA damage in a p53-dependent manner. FATS expression was silent or downregulated in human cancers, and overexpression of FATS suppressed tumorigenicity in vivo independently of p53. Our results reveal FATS as a p53-regulated gene to monitor genomic stability.

  12. Pifithrin-α provides neuroprotective effects at the level of mitochondria independently of p53 inhibition.

    Science.gov (United States)

    Neitemeier, Sandra; Ganjam, Goutham K; Diemert, Sebastian; Culmsee, Carsten

    2014-12-01

    Impaired mitochondrial integrity and function are key features of intrinsic death pathways in neuronal cells. Therefore, key regulators of intrinsic death pathways acting upstream of mitochondria are potential targets for therapeutic approaches of neuroprotection. The tumor suppressor p53 is a well-established regulator of cellular responses towards different kinds of lethal stress, including oxidative stress. Recent reports suggested that p53 may affect mitochondrial integrity and function through both, transcriptional activation of mitochondria-targeted pro-death proteins and direct effects at the mitochondrial membrane. In the present study, we compared the effects of pharmacological inhibition of p53 by pifithrin-α with those of selective p53 gene silencing by RNA interference. Using MTT assay and real-time cell impedance measurements we confirmed the protective effect of both strategies against glutamate-induced oxidative stress in immortalized mouse hippocampal HT-22 neurons. Further, we observed full restoration of mitochondrial membrane potential and inhibition of glutamate-induced mitochondrial fragmentation by pifithrin-α which was, in contrast, not achieved by p53 gene silencing. Downregulation of p53 by siRNA decreased p53 transcriptional activity and reduced expression levels of p21 mRNA, while pifithrin-α did not affect these endpoints. These results suggest a neuroprotective effect of pifithrin-α which occurred at the level of mitochondria and independently of p53 inhibition.

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

    Science.gov (United States)

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

    1990-11-30

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

  14. miR-34 and p53: New Insights into a Complex Functional Relationship.

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    Francisco Navarro

    Full Text Available miR-34, a tumor suppressor miRNA family transcriptionally activated by p53, is considered a critical mediator of p53 function. However, knockout of the mouse miR-34 family has little or no effect on the p53 response. The relative contribution of different miR-34 family members to p53 function or how much p53 relies on miR-34 in human cells is unclear. Here we show that miR-34a has a complex effect on the p53 response in human cells. In HCT116 cells miR-34a overexpression enhances p53 transcriptional activity, but the closely related family members, miR-34b and miR-34c, even when over-expressed, have little effect. Both TP53 itself and MDM4, a strong p53 transactivation inhibitor, are direct targets of miR-34a. The genes regulated by miR-34a also include four other post-translational inhibitors of p53. miR-34a overexpression leads to variable effects on p53 levels in p53-sufficient human cancer cell lines. In HCT116, miR-34a overexpression increases p53 protein levels and stability. About a quarter of all mRNAs that participate in the human p53 network bind to biotinylated miR-34a, suggesting that many are direct miR-34a targets. However, only about a fifth of the mRNAs that bind to miR-34a also bind to miR-34b or miR-34c. Two human cell lines knocked out for miR-34a have unimpaired p53-mediated responses to genotoxic stress, like mouse cells. The complex positive and negative effects of miR-34 on the p53 network suggest that rather than simply promoting the p53 response, miR-34a might act at a systems level to stabilize the robustness of the p53 response to genotoxic stress.

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

    International Nuclear Information System (INIS)

    Pauklin, Siim; Kristjuhan, Arnold; Maimets, Toivo; Jaks, Viljar

    2005-01-01

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

  16. Bladder-like graphical representation of p53 gene alterations in some human cancers

    International Nuclear Information System (INIS)

    Helal, N.L.; Dorrah, M.; LI, C.

    2005-01-01

    the p53 tumor suppressor gene is mutated in about half of all human cancer cells. These mutations are not only important in tumor progression but apparently also in the response of some tumors to chemotherapy and radiation treatment, thus to clinical outcome. Recent studies have shown that cells carrying p53 mutations are more resistant to radiation and chemotherapy than cells with functional p53. More than 15000 tumors with Tp53 mutations were published, leadingto the description of more than 1500 different Tp53 mutants (at the site http:// p53. curie.fr). To exploit this huge bulk of data, specific analytic tools were highly warranted. Also, new computational techniques for rapid determination of such information and comparative studies of different mutations are required. In the present study, a mathematical method for the IARC library p53 mutation database comparing p53 mutations occurring in four different cancers was described. The sizes of the four cancers in the database were bladder (860), liver (786), brain (1170) and skin (38) cancers, for a total of 2854 of p53 mutations. The study was carried out on exons 4-8 of p53 for the four cancers under investigation. From this study, it can be quantitatively obtained some information for each characteristic sequence. The data showed that exon 8 was the most mutant exon in skin cancer and exon 7 was the lowest one. In hepatocellular carcinoma, exon 4 was the most mutant exon and exon 7 was the lowest mutant exon. Brain cancer showed high mutation in exon 8 and low mutation at exon 6. Finally, bladder mutation was mostly mutated at exon 6 comparing to the least value of exon 7. It is expected that this study of p53 mutation may provide useful information for the diagnosis, prognosis and treatment of cancer

  17. Tumores da córtex da supra-renal: o uso do p53 na diferenciação entre carcinomas e adenomas

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    Falconi Rodrigo A. R.

    2000-01-01

    Full Text Available A marcação imunohistoquímica da proteina p53 foi estudada em tumores da adrenal conservados em formol ou em blocos de parafina, pelo método da avidina-biotina-peroxidase com recuperação antigênica. Foram estudados 24 carcinomas e 26 adenomas com o objetivo de verificar se o marcador mostrava capacidade de distinção entre eles. Em 62,5% dos carcinomas a marcação foi positiva enquanto que nos adenomas foi de 15,4%, diferença essa estatisticamente significante (p=0,0003. A sensibilidade, especificidade e valor preditivo positivo desse marcador para o diagnóstico do câncer foram, respectivamente: 83,3%, 71,8% e 62,5%. Não houve relação entre o índice de marcação e outros parâmetros clínicos, como peso do tumor, estádio local, recidiva e metástases. Os autores concluem que o marcador é útil no diagnóstico diferencial de massas da adrenal, mas não tem relação com a agressividade biológica da neoplasia maligna.

  18. The 5S RNP couples p53 homeostasis to ribosome biogenesis and nucleolar stress.

    Science.gov (United States)

    Sloan, Katherine E; Bohnsack, Markus T; Watkins, Nicholas J

    2013-10-17

    Several proto-oncogenes and tumor suppressors regulate the production of ribosomes. Ribosome biogenesis is a major consumer of cellular energy, and defects result in p53 activation via repression of mouse double minute 2 (MDM2) homolog by the ribosomal proteins RPL5 and RPL11. Here, we report that RPL5 and RPL11 regulate p53 from the context of a ribosomal subcomplex, the 5S ribonucleoprotein particle (RNP). We provide evidence that the third component of this complex, the 5S rRNA, is critical for p53 regulation. In addition, we show that the 5S RNP is essential for the activation of p53 by p14(ARF), a protein that is activated by oncogene overexpression. Our data show that the abundance of the 5S RNP, and therefore p53 levels, is determined by factors regulating 5S complex formation and ribosome integration, including the tumor suppressor PICT1. The 5S RNP therefore emerges as the critical coordinator of signaling pathways that couple cell proliferation with ribosome production. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Interaction between the Cockayne syndrome B and p53 proteins: implications for aging.

    Science.gov (United States)

    Frontini, Mattia; Proietti-De-Santis, Luca

    2012-02-01

    The CSB protein plays a role in the transcription coupled repair (TCR) branch of the nucleotide excision repair pathway. CSB is very often found mutated in Cockayne syndrome, a segmental progeroid genetic disease characterized by organ degeneration and growth failure. The tumor suppressor p53 plays a pivotal role in triggering senescence and apoptosis and suppressing tumorigenesis. Although p53 is very important to avoid cancer, its excessive activity can be detrimental for the lifespan of the organism. This is why a network of positive and negative feedback loops, which most likely evolved to fine-tune the activity of this tumor suppressor, modulate its induction and activation. Accordingly, an unbalanced p53 activity gives rise to premature aging or cancer. The physical interaction between CSB and p53 proteins has been known for more than a decade but, despite several hypotheses, nobody has been able to show the functional consequences of this interaction. In this review we resume recent advances towards a more comprehensive understanding of the critical role of this interaction in modulating p53’s levels and activity, therefore helping the system find a reasonable equilibrium between the beneficial and the detrimental effects of its activity. This crosstalk re-establishes the physiological balance towards cell proliferation and survival instead of towards cell death, after stressors of a broad nature. Accordingly, cells bearing mutations in the csb gene are unable to re-establish this physiological balance and to properly respond to some stress stimuli and undergo massive apoptosis.

  20. RUNX Family Participates in the Regulation of p53-Dependent DNA Damage Response

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    Toshinori Ozaki

    2013-01-01

    Full Text Available A proper DNA damage response (DDR, which monitors and maintains the genomic integrity, has been considered to be a critical barrier against genetic alterations to prevent tumor initiation and progression. The representative tumor suppressor p53 plays an important role in the regulation of DNA damage response. When cells receive DNA damage, p53 is quickly activated and induces cell cycle arrest and/or apoptotic cell death through transactivating its target genes implicated in the promotion of cell cycle arrest and/or apoptotic cell death such as p21WAF1, BAX, and PUMA. Accumulating evidence strongly suggests that DNA damage-mediated activation as well as induction of p53 is regulated by posttranslational modifications and also by protein-protein interaction. Loss of p53 activity confers growth advantage and ensures survival in cancer cells by inhibiting apoptotic response required for tumor suppression. RUNX family, which is composed of RUNX1, RUNX2, and RUNX3, is a sequence-specific transcription factor and is closely involved in a variety of cellular processes including development, differentiation, and/or tumorigenesis. In this review, we describe a background of p53 and a functional collaboration between p53 and RUNX family in response to DNA damage.

  1. p53 protein expression versus micronucleus induction as an indicator of DNA damage

    International Nuclear Information System (INIS)

    Hickman, A.W.; Carpenter, T.R.; Johnson, N.F.

    1994-01-01

    In vitro assays for detecting DNA damage play an important role in evaluating the possible adverse health effects of chemical compounds. Exposure to many DNA-damaging agents in vitro has been shown to cause elevated levels of the tumor-suppressor protein p53. Work in our laboratory has shown that induction of the p53 protein is useful as a biodosimeter for determining the radiation dose to cells. The purpose of this investigation was to compare the sensitivity of this assay to that of micronucleus induction, which is commonly used as a marker of radiation-induced damage

  2. FATS is a transcriptional target of p53 and associated with antitumor activity

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    Zhang Xifeng; Zhang Qian; Zhang Jun; Qiu Li; Yan Shuang-shuang; Feng Juling; Sun Yan; Huang Xingxu; Lu Karen H; Li Zheng

    2010-01-01

    Abstract Frequent mutations of p53 in human cancers exemplify its crucial role as a tumor suppressor transcription factor, and p21, a transcriptional target of p53, plays a central role in surveillance of cell-cycle checkpoints. Our previous study has shown that FATS stabilize p21 to preserve genome integrity. In this study we identified a novel transcript variant of FATS (GenBank: GQ499374) through screening a cDNA library from mouse testis, which uncovered the promoter region of mouse FATS....

  3. HMGB1-mediated DNA bending: Distinct roles in increasing p53 binding to DNA and the transactivation of p53-responsive gene promoters.

    Science.gov (United States)

    Štros, Michal; Kučírek, Martin; Sani, Soodabeh Abbasi; Polanská, Eva

    2018-03-01

    HMGB1 is a chromatin-associated protein that has been implicated in many important biological processes such as transcription, recombination, DNA repair, and genome stability. These functions include the enhancement of binding of a number of transcription factors, including the tumor suppressor protein p53, to their specific DNA-binding sites. HMGB1 is composed of two highly conserved HMG boxes, linked to an intrinsically disordered acidic C-terminal tail. Previous reports have suggested that the ability of HMGB1 to bend DNA may explain the in vitro HMGB1-mediated increase in sequence-specific DNA binding by p53. The aim of this study was to reinvestigate the importance of HMGB1-induced DNA bending in relationship to the ability of the protein to promote the specific binding of p53 to short DNA duplexes in vitro, and to transactivate two major p53-regulated human genes: Mdm2 and p21/WAF1. Using a number of HMGB1 mutants, we report that the HMGB1-mediated increase in sequence-specific p53 binding to DNA duplexes in vitro depends very little on HMGB1-mediated DNA bending. The presence of the acidic C-terminal tail of HMGB1 and/or the oxidation of the protein can reduce the HMGB1-mediated p53 binding. Interestingly, the induction of transactivation of p53-responsive gene promoters by HMGB1 requires both the ability of the protein to bend DNA and the acidic C-terminal tail, and is promoter-specific. We propose that the efficient transactivation of p53-responsive gene promoters by HMGB1 depends on complex events, rather than solely on the promotion of p53 binding to its DNA cognate sites. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Regulation of Metabolic Activity by p53

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    Jessica Flöter

    2017-05-01

    Full Text Available Metabolic reprogramming in cancer cells is controlled by the activation of multiple oncogenic signalling pathways in order to promote macromolecule biosynthesis during rapid proliferation. Cancer cells also need to adapt their metabolism to survive and multiply under the metabolically compromised conditions provided by the tumour microenvironment. The tumour suppressor p53 interacts with the metabolic network at multiple nodes, mostly to reduce anabolic metabolism and promote preservation of cellular energy under conditions of nutrient restriction. Inactivation of this tumour suppressor by deletion or mutation is a frequent event in human cancer. While loss of p53 function lifts an important barrier to cancer development by deleting cell cycle and apoptosis checkpoints, it also removes a crucial regulatory mechanism and can render cancer cells highly sensitive to metabolic perturbation. In this review, we will summarise the major concepts of metabolic regulation by p53 and explore how this knowledge can be used to selectively target p53 deficient cancer cells in the context of the tumour microenvironment.

  5. Radiosensitivity of cancer cells against carbon-ion beams in an aspect of the p53 gene status

    International Nuclear Information System (INIS)

    Takahashi, Akihisa; Ohnishi, Takeo; Matsumoto, Hideki

    2004-01-01

    We can easily understand that radiation sensitivities of cancer cells are dependent on the status of cancer-related genes. It is important to clarify which genes affect radiation sensitivity and reflect the effectiveness of radiation therapy for cancer cells. We have studied about the function of a tumor suppressor gene of p53, because p53 controls apoptosis, cell cycle and DNA repair from an aspect of important roles in cell fate. By analysis of function of p53 gene, therefore, we aim to predict the therapeutic effectiveness and to select the modalities of cancer therapies such as radiotherapy, chemotherapy and hyperthermia. As a final goal, we want to accept the most effective therapy, namely tailor-made cancer therapy, for each patient. Here, we introduce that carbon-beam therapy induced the expression of p53-independent apoptosis-related genes and NO radicals in mutated p53 cancer cells. (author)

  6. Interaction of an anticancer peptide fragment of azurin with p53 and its isolated domains studied by atomic force spectroscopy.

    Science.gov (United States)

    Bizzarri, Anna Rita; Santini, Simona; Coppari, Emilia; Bucciantini, Monica; Di Agostino, Silvia; Yamada, Tohru; Beattie, Craig W; Cannistraro, Salvatore

    2011-01-01

    p28 is a 28-amino acid peptide fragment of the cupredoxin azurin derived from Pseudomonas aeruginosa that preferentially penetrates cancerous cells and arrests their proliferation in vitro and in vivo. Its antitumor activity reportedly arises from post-translational stabilization of the tumor suppressor p53 normally downregulated by the binding of several ubiquitin ligases. This would require p28 to specifically bind to p53 to inhibit specific ligases from initiating proteosome-mediated degradation. In this study, atomic force spectroscopy, a nanotechnological approach, was used to investigate the interaction of p28 with full-length p53 and its isolated domains at the single molecule level. Analysis of the unbinding forces and the dissociation rate constant suggest that p28 forms a stable complex with the DNA-binding domain of p53, inhibiting the binding of ubiquitin ligases other than Mdm2 to reduce proteasomal degradation of p53.

  7. Distinct p53 genomic binding patterns in normal and cancer-derived human cells

    Energy Technology Data Exchange (ETDEWEB)

    Botcheva K.; McCorkle S. R.; McCombie W. R.; Dunn J. J.; Anderson C. W.

    2011-12-15

    We report here genome-wide analysis of the tumor suppressor p53 binding sites in normal human cells. 743 high-confidence ChIP-seq peaks representing putative genomic binding sites were identified in normal IMR90 fibroblasts using a reference chromatin sample. More than 40% were located within 2 kb of a transcription start site (TSS), a distribution similar to that documented for individually studied, functional p53 binding sites and, to date, not observed by previous p53 genome-wide studies. Nearly half of the high-confidence binding sites in the IMR90 cells reside in CpG islands, in marked contrast to sites reported in cancer-derived cells. The distinct genomic features of the IMR90 binding sites do not reflect a distinct preference for specific sequences, since the de novo developed p53 motif based on our study is similar to those reported by genome-wide studies of cancer cells. More likely, the different chromatin landscape in normal, compared with cancer-derived cells, influences p53 binding via modulating availability of the sites. We compared the IMR90 ChIPseq peaks to the recently published IMR90 methylome1 and demonstrated that they are enriched at hypomethylated DNA. Our study represents the first genome-wide, de novo mapping of p53 binding sites in normal human cells and reveals that p53 binding sites reside in distinct genomic landscapes in normal and cancer-derived human cells.

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

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    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

  9. The Inherited p53 Mutation in the Brazilian Population.

    Science.gov (United States)

    Achatz, Maria Isabel; Zambetti, Gerard P

    2016-12-01

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

  10. p53 Loss Synergizes with Estrogen and Papillomaviral Oncogenes to Induce Cervical and Breast Cancers

    Science.gov (United States)

    Shai, Anny; Pitot, Henry C.; Lambert, Paul F.

    2010-01-01

    Whereas the tumor suppressor p53 gene is frequently mutated in most human cancers, this is not the case in human papillomavirus (HPV)-associated cancers, presumably because the viral E6 oncoprotein inactivates the p53 protein. The ability of E6 to transform cells in tissue culture and induce cancers in mice correlates in part with its ability to inactivate p53. In this study, we compared the expression of the HPV16 E6 oncogene to the conditional genetic disruption of p53 in the context of a mouse model for cervical cancer in which estrogen is a critical cofactor. Nearly all of the K14Crep53f/f mice treated with estrogen developed cervical cancer, a stark contrast to its complete absence in like-treated K14E6WTp53f/f mice, indicating that HPV16 E6 must only partially inactivate p53. p53-independent activities of E6 also contributed to carcinogenesis, but in the female reproductive tract, these activities were manifested only in the presence of the HPV16 E7 oncogene. Interestingly, treatment of K14Crep53f/f mice with estrogen also resulted in mammary tumors after only a short latency, many of which were positive for estrogen receptor α. The majority of these mammary tumors were of mixed cell types, suggestive of their originating from a multipotent progenitor. Furthermore, a subset of mammary tumors arising in the estrogen-treated, p53-deficient mammary glands exhibited evidence of an epithelial to mesenchymal transition. These data show the importance of the synergy between estrogen and p53 insufficiency in determining basic properties of carcinogenesis in hormone-responsive tissues, such as the breast and the reproductive tract. PMID:18413729

  11. Long Non-Coding RNAs Embedded in the Rb and p53 Pathways

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    Subramanian, Murugan; Jones, Matthew F.; Lal, Ashish, E-mail: ashish.lal@nih.gov [Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States)

    2013-12-04

    In recent years, long non-coding RNAs (lncRNAs) have gained significant attention as a novel class of gene regulators. Although a small number of lncRNAs have been shown to regulate gene expression through diverse mechanisms including transcriptional regulation, mRNA splicing and translation, the physiological function and mechanism of action of the vast majority are not known. Profiling studies in cell lines and tumor samples have suggested a potential role of lncRNAs in cancer. Indeed, distinct lncRNAs have been shown to be embedded in the p53 and Rb networks, two of the major tumor suppressor pathways that control cell cycle progression and survival. Given the fact that inactivation of Rb and p53 is a hallmark of human cancer, in this review we discuss recent evidence on the function of lncRNAs in the Rb and p53 signaling pathways.

  12. Long Non-Coding RNAs Embedded in the Rb and p53 Pathways

    International Nuclear Information System (INIS)

    Subramanian, Murugan; Jones, Matthew F.; Lal, Ashish

    2013-01-01

    In recent years, long non-coding RNAs (lncRNAs) have gained significant attention as a novel class of gene regulators. Although a small number of lncRNAs have been shown to regulate gene expression through diverse mechanisms including transcriptional regulation, mRNA splicing and translation, the physiological function and mechanism of action of the vast majority are not known. Profiling studies in cell lines and tumor samples have suggested a potential role of lncRNAs in cancer. Indeed, distinct lncRNAs have been shown to be embedded in the p53 and Rb networks, two of the major tumor suppressor pathways that control cell cycle progression and survival. Given the fact that inactivation of Rb and p53 is a hallmark of human cancer, in this review we discuss recent evidence on the function of lncRNAs in the Rb and p53 signaling pathways

  13. Basal p53 expression is indispensable for mesenchymal stem cell integrity.

    Science.gov (United States)

    Boregowda, Siddaraju V; Krishnappa, Veena; Strivelli, Jacqueline; Haga, Christopher L; Booker, Cori N; Phinney, Donald G

    2018-03-01

    Marrow-resident mesenchymal stem cells (MSCs) serve as a functional component of the perivascular niche that regulates hematopoiesis. They also represent the main source of bone formed in adult bone marrow, and their bifurcation to osteoblast and adipocyte lineages plays a key role in skeletal homeostasis and aging. Although the tumor suppressor p53 also functions in bone organogenesis, homeostasis, and neoplasia, its role in MSCs remains poorly described. Herein, we examined the normal physiological role of p53 in primary MSCs cultured under physiologic oxygen levels. Using knockout mice and gene silencing we show that p53 inactivation downregulates expression of TWIST2, which normally restrains cellular differentiation to maintain wild-type MSCs in a multipotent state, depletes mitochondrial reactive oxygen species (ROS) levels, and suppresses ROS generation and PPARG gene and protein induction in response to adipogenic stimuli. Mechanistically, this loss of adipogenic potential skews MSCs toward an osteogenic fate, which is further potentiated by TWIST2 downregulation, resulting in highly augmented osteogenic differentiation. We also show that p53 - /- MSCs are defective in supporting hematopoiesis as measured in standard colony assays because of decreased secretion of various cytokines including CXCL12 and CSF1. Lastly, we show that transient exposure of wild-type MSCs to 21% oxygen upregulates p53 protein expression, resulting in increased mitochondrial ROS production and enhanced adipogenic differentiation at the expense of osteogenesis, and that treatment of cells with FGF2 mitigates these effects by inducing TWIST2. Together, these findings indicate that basal p53 levels are necessary to maintain MSC bi-potency, and oxygen-induced increases in p53 expression modulate cell fate and survival decisions. Because of the critical function of basal p53 in MSCs, our findings question the use of p53 null cell lines as MSC surrogates, and also implicate dysfunctional

  14. Prognostic value of tumor suppressors in osteosarcoma before and after neoadjuvant chemotherapy

    International Nuclear Information System (INIS)

    Robl, Bernhard; Pauli, Chantal; Botter, Sander Martijn; Bode-Lesniewska, Beata; Fuchs, Bruno

    2015-01-01

    Primary bone cancers are among the deadliest cancer types in adolescents, with osteosarcomas being the most prevalent form. Osteosarcomas are commonly treated with multi-drug neoadjuvant chemotherapy and therapy success as well as patient survival is affected by the presence of tumor suppressors. In order to assess the prognostic value of tumor-suppressive biomarkers, primary osteosarcoma tissues were analyzed prior to and after neoadjuvant chemotherapy. We constructed a tissue microarray from high grade osteosarcoma samples, consisting of 48 chemotherapy naïve biopsies (BXs) and 47 tumor resections (RXs) after neoadjuvant chemotherapy. We performed immunohistochemical stainings of P53, P16, maspin, PTEN, BMI1 and Ki67, characterized the subcellular localization and related staining outcome with chemotherapy response and overall survival. Binary logistic regression analysis was used to analyze chemotherapy response and Kaplan-Meier-analysis as well as the Cox proportional hazards model was applied for analysis of patient survival. No significant associations between biomarker expression in BXs and patient survival or chemotherapy response were detected. In univariate analysis, positive immunohistochemistry of P53 (P = 0.008) and P16 (P16; P = 0.033) in RXs was significantly associated with poor survival prognosis. In addition, presence of P16 in RXs was associated with poor survival in multivariate regression analysis (P = 0.003; HR = 0.067) while absence of P16 was associated with good chemotherapy response (P = 0.004; OR = 74.076). Presence of PTEN on tumor RXs was significantly associated with an improved survival prognosis (P = 0.022). Positive immunohistochemistry (IHC) of P16 and P53 in RXs was indicative for poor overall patient survival whereas positive IHC of PTEN was prognostic for good overall patient survival. In addition, we found that P16 might be a marker of osteosarcoma chemotherapy resistance. Therefore, our study supports the use of tumor RXs to

  15. BDNF: An Oncogene or Tumor Suppressor?

    Science.gov (United States)

    Radin, Daniel P; Patel, Parth

    2017-08-01

    Neurotrophins are a family of growth factors that are vital to the proper development of the central nervous system. Their effects on cells are governed by the expression and activation of the tyrosine kinase receptors TrkA, TrkB and TrkC. TrkB has been immensely implicated in mediating neuronal migration, development and differentiation. It has also been shown to protect several neuronal cell types from an array of cytotoxic stressors after activation by its conjugate ligand brain-derived neurotrophic factor (BDNF). Over the past two decades, it has been shown that TrkB and BDNF are up-regulated in many types of cancers, conferring aggressive phenotypes underpinned by their resistance to several standard chemotherapeutic agents. This resistance to chemotherapy is modulated by the downstream targets of the TrkB receptor which include the well-characterized PI3K /Akt growth pathway, a hallmark of uncontrolled cancer cell growth and proliferation. Pre-clinical efforts to develop inhibitors of this receptor are promising, and such inhibitors also seem to sensitize cancer cells to standard chemotherapies. However, new evidence suggests that BDNF overexpression in the hypothalamus has immunoaugmenting properties, eliciting an increased anti-tumor immune response and reducing the activity of several proteins that would normally confer resistance to chemotherapeutic agents. In the current work, we provide a global analysis of the physiological consequences of TrkB receptor activation in vitro and discuss the dynamic consequences of TrkB activation in vivo. Finally, we propose a clinically-feasible option for increasing BDNF expression in the hypothalamus to more readily utilize the oncolytic effects of BDNF. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  16. Non-Canonical Cell Death Induced by p53

    Directory of Open Access Journals (Sweden)

    Atul Ranjan

    2016-12-01

    Full Text Available Programmed cell death is a vital biological process for multicellular organisms to maintain cellular homeostasis, which is regulated in a complex manner. Over the past several years, apart from apoptosis, which is the principal mechanism of caspase-dependent cell death, research on non-apoptotic forms of programmed cell death has gained momentum. p53 is a well characterized tumor suppressor that controls cell proliferation and apoptosis and has also been linked to non-apoptotic, non-canonical cell death mechanisms. p53 impacts these non-canonical forms of cell death through transcriptional regulation of its downstream targets, as well as direct interactions with key players involved in these mechanisms, in a cell type- or tissue context-dependent manner. In this review article, we summarize and discuss the involvement of p53 in several non-canonical modes of cell death, including caspase-independent apoptosis (CIA, ferroptosis, necroptosis, autophagic cell death, mitotic catastrophe, paraptosis, and pyroptosis, as well as its role in efferocytosis which is the process of clearing dead or dying cells.

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

    Directory of Open Access Journals (Sweden)

    Evguenia eAlexandrova

    2015-04-01

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

  18. Immunohistochemical Expression of p53 in Pleomorphic Adenoma and Carcinoma Ex Pleomorphic Adenoma

    International Nuclear Information System (INIS)

    Tarakji, B.; Kujan, O.; Nassani, M. Z.

    2010-01-01

    Context. Immunohistochemical stains for p53 are used as a diagnostic marker associated with malignancy in several histologic types of salivary gland tumors. This marker may be useful in differentiating pleomorphic adenoma (PA) from carcinoma ex pleomorphic adenoma (CPA), as these tumors are often difficult to distinguish on the basis of morphology alone. Objective. to evaluate whatever inactivation of tumor suppressor gene (p53) increases with the tumor progression from normal salivary tissue to PA and eventually CPA. Design. Paraffin blocks of 29 cases of PA, which were surrounded by normal parotid gland, and 27 cases of carcinoma ex pleomorphic adenoma were retrieved and validated. In all cases of carcinoma ex pleomorphic adenoma, a PA “ghost” was identified, and the malignant element was either undifferentiated carcinoma or adenocarcinoma. Results. The results showed negative nuclear expression of P53 in normal parotid gland. Nuclear P53 was expressed strongly in 6/29 (20.7%) pleomorphic salivary adenoma and 10/27 (37%) carcinoma ex pleomorphic adenoma. Conclusion. Our data suggest that inactivation of p53 may play an important role in the evolution of pleomorphic salivary adenoma and carcinoma ex pleomorphic adenoma.

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

    Science.gov (United States)

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

    2006-04-01

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

  20. Epstein–Barr virus nuclear antigen 3C interact with p73: Interplay between a viral oncoprotein and cellular tumor suppressor

    International Nuclear Information System (INIS)

    Sahu, Sushil Kumar; Mohanty, Suchitra; Kumar, Amit; Kundu, Chanakya N.; Verma, Subhash C.; Choudhuri, Tathagata

    2014-01-01

    The p73 protein has structural and functional homology with the tumor suppressor p53, which plays an important role in cell cycle regulation, apoptosis, and DNA repair. The p73 locus encodes both a tumor suppressor (TAp73) and a putative oncogene (ΔNp73). p73 May play a significant role in p53-deficient lymphomas infected with Epstein–Barr virus (EBV). EBV produces an asymptomatic infection in the majority of the global population, but it is associated with several human B-cell malignancies. The EBV-encoded Epstein–Barr virus nuclear antigen 3C (EBNA3C) is thought to disrupt the cell cycle checkpoint by interacting directly with p53 family proteins. Doxorubicin, a commonly used chemotherapeutic agent, induces apoptosis through p53 and p73 signaling such that the lowΔNp73 level promotes the p73-mediated intrinsic pathway of apoptosis. In this report, we investigated the mechanism by which EBV infection counters p73α-induced apoptosis through EBNA3C. - Highlights: • EBV-encoded EBNA3C suppresses doxorubicin-induced apoptosis in B-cell lymphomas. • EBNA3C binds to p73 to suppress its apoptotic effect. • EBNA3C maintains latency by regulating downstream mitochondrial pathways

  1. Epstein–Barr virus nuclear antigen 3C interact with p73: Interplay between a viral oncoprotein and cellular tumor suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Sushil Kumar; Mohanty, Suchitra; Kumar, Amit [Division of Infectious Disease Biology, Institute of Life Sciences, Nalco Square, Chandrasekharpur, Bhubaneswar 751023 (India); Kundu, Chanakya N. [School of Biotechnology, KIIT University, Bhubaneswar (India); Verma, Subhash C. [Department of Microbiology and Immunology, University of Nevada, School of Medicine, Reno, NV 89557 (United States); Choudhuri, Tathagata, E-mail: tatha@ils.res.in [Division of Infectious Disease Biology, Institute of Life Sciences, Nalco Square, Chandrasekharpur, Bhubaneswar 751023 (India); Department of Biotechnology, Siksha Bhavana, Visva Bharati, Santiniketan, Bolpur (India)

    2014-01-05

    The p73 protein has structural and functional homology with the tumor suppressor p53, which plays an important role in cell cycle regulation, apoptosis, and DNA repair. The p73 locus encodes both a tumor suppressor (TAp73) and a putative oncogene (ΔNp73). p73 May play a significant role in p53-deficient lymphomas infected with Epstein–Barr virus (EBV). EBV produces an asymptomatic infection in the majority of the global population, but it is associated with several human B-cell malignancies. The EBV-encoded Epstein–Barr virus nuclear antigen 3C (EBNA3C) is thought to disrupt the cell cycle checkpoint by interacting directly with p53 family proteins. Doxorubicin, a commonly used chemotherapeutic agent, induces apoptosis through p53 and p73 signaling such that the lowΔNp73 level promotes the p73-mediated intrinsic pathway of apoptosis. In this report, we investigated the mechanism by which EBV infection counters p73α-induced apoptosis through EBNA3C. - Highlights: • EBV-encoded EBNA3C suppresses doxorubicin-induced apoptosis in B-cell lymphomas. • EBNA3C binds to p73 to suppress its apoptotic effect. • EBNA3C maintains latency by regulating downstream mitochondrial pathways.

  2. The adenovirus oncoprotein E1a stimulates binding of transcription factor ETF to transcriptionally activate the p53 gene.

    Science.gov (United States)

    Hale, T K; Braithwaite, A W

    1999-08-20

    Expression of the tumor suppressor protein p53 plays an important role in regulating the cellular response to DNA damage. During adenovirus infection, levels of p53 protein also increase. It has been shown that this increase is due not only to increased stability of the p53 protein but to the transcriptional activation of the p53 gene during infection. We demonstrate here that the E1a proteins of adenovirus are responsible for activating the mouse p53 gene and that both major E1a proteins, 243R and 289R, are required for complete activation. E1a brings about the binding of two cellular transcription factors to the mouse p53 promoter. One of these, ETF, binds to three upstream sites in the p53 promoter and one downstream site, whereas E2F binds to one upstream site in the presence of E1a. Our studies indicate that E2F binding is not essential for activation of the p53 promoter but that ETF is. Our data indicate the ETF site located downstream of the start site of transcription is the key site in conferring E1a responsiveness on the p53 promoter.

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

    Science.gov (United States)

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

    2011-08-15

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

  4. Antiproliferative and Apoptotic Effect of Dendrosomal Curcumin Nanoformulation in P53 Mutant and Wide-Type Cancer Cell Lines.

    Science.gov (United States)

    Montazeri, Maryam; Pilehvar-Soltanahmadi, Younes; Mohaghegh, Mina; Panahi, Alireza; Khodi, Samaneh; Zarghami, Nosratollah; Sadeghizadeh, Majid

    2017-01-01

    The aim of this paper is to investigate the effect of dendrosomal curcumin (DNC) on the expression of p53 in both p53 mutant cell lines SKBR3/SW480 and p53 wild-type MCF7/HCT116 in both RNA and protein levels. Curcumin, derived from Curcumin longa, is recently considered in cancer related researches for its cell growth inhibition properties. p53 is a common tumor-suppressor gene involved in cancers and its mutation not only inhibits tumor suppressor activity but also promotes oncogenic activity. Here, p53 mutant/Wild-type cells were employed to study the toxicity of DNC using MTT assay, Flow cytometry and Annexin-V, Real-time PCR and Western blot were used to analyze p53, BAX, Bcl-2, p21 and Noxa changes after treatment. During the time, DNC increased the SubG1 cells and decreased G1, S and G2/M cells, early apoptosis also indicated the inhibition of cell growth in early phase. Real-Time PCR assay showed an increased mRNA of BAX, Noxa and p21 during the time with decreased Bcl-2. The expression of p53 mutant decreased in SKBR3/SW480, and the expression of p53 wild-type increased in MCF7/HCT116. Consequently, p53 plays an important role in mediating the survival by DNC, which can prevent tumor cell growth by modulating the expression of genes involved in apoptosis and proliferation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  5. RITA enhances chemosensivity of pre-B ALL cells to doxorubicin by inducing p53-dependent apoptosis.

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    Kazemi, Ahmad; Safa, Majid; Shahbazi, Atefeh

    2011-07-01

    The use of low-molecular-weight, non-peptidic molecules that disrupt the interaction between the p53 tumor suppressor and its negative regulator MDM2 has provided a promising alternative for the treatment of different types of cancer. Here, we used small-molecule reactivation of p53 and induction of tumor cell apoptosis (RITA) to sensitize leukemic NALM-6 cells to doxorubicin by upregulating p53 protein. RITA alone effectively inhibited NALM-6 cells viability in dose-dependent manner as measured by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay and induced apoptosis as evaluated by flow cytometry, whereas RITA in combination with doxorubicin enhanced NALM-6 cells to doxorubicin-sensitivity and promoted doxorubicin induced apoptosis. Levels of p53 protein and its proapoptotic target genes, quantified by western blot and real-time PCR respectively, showed that expression of p53 was significantly increased after RITA treatment. Using p53 inhibitors PFT-alpha and PFT-mu it was shown that p53-mediated apoptosis induced by RITA can be regulated by both p53-transcription-dependent and -independent pathways. Moreover, RITA-induced apoptosis was accompanied by the activation of caspase-3 and PARP cleavage. Therefore, exploiting synergistic effects between RITA and chemotherapeutics might be an effective clinical strategy for leukemia chemotherapy.

  6. Wild type p53 transcriptionally represses the SALL2 transcription factor under genotoxic stress.

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    Carlos Farkas

    Full Text Available SALL2- a member of the Spalt gene family- is a poorly characterized transcription factor found deregulated in various cancers, which suggests it plays a role in the disease. We previously identified SALL2 as a novel interacting protein of neurotrophin receptors and showed that it plays a role in neuronal function, which does not necessarily explain why or how SALL2 is deregulated in cancer. Previous evidences indicate that SALL2 gene is regulated by the WT1 and AP4 transcription factors. Here, we identified SALL2 as a novel downstream target of the p53 tumor suppressor protein. Bioinformatic analysis of the SALL2 gene revealed several putative p53 half sites along the promoter region. Either overexpression of wild-type p53 or induction of the endogenous p53 by the genotoxic agent doxorubicin repressed SALL2 promoter activity in various cell lines. However R175H, R249S, and R248W p53 mutants, frequently found in the tumors of cancer patients, were unable to repress SALL2 promoter activity, suggesting that p53 specific binding to DNA is important for the regulation of SALL2. Electrophoretic mobility shift assay demonstrated binding of p53 to one of the identified p53 half sites in the Sall2 promoter, and chromatin immunoprecipitation analysis confirmed in vivo interaction of p53 with the promoter region of Sall2 containing this half site. Importantly, by using a p53ER (TAM knockin model expressing a variant of p53 that is completely dependent on 4-hydroxy-tamoxifen for its activity, we show that p53 activation diminished SALL2 RNA and protein levels during genotoxic cellular stress in primary mouse embryo fibroblasts (MEFs and radiosensitive tissues in vivo. Thus, our finding indicates that p53 represses SALL2 expression in a context-specific manner, adding knowledge to the understanding of SALL2 gene regulation, and to a potential mechanism for its deregulation in cancer.

  7. The MDM2-inhibitor Nutlin-3 synergizes with cisplatin to induce p53 dependent tumor cell apoptosis in non-small cell lung cancer

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    Deben, Christophe; Wouters, An; de Beeck, Ken Op; van Den Bossche, Jolien; Jacobs, Julie; Zwaenepoel, Karen; Peeters, Marc; Van Meerbeeck, Jan; Lardon, Filip; Rolfo, Christian; Deschoolmeester, Vanessa; Pauwels, Patrick

    2015-01-01

    The p53/MDM2 interaction has been a well-studied target for new drug design leading to the development of the small molecule inhibitor Nutlin-3. Our objectives were to combine Nutlin-3 with cisplatin (CDDP), a well-known activator of the p53 pathway, in a series of non-small cell lung cancer cell lines in order to increase the cytotoxic response to CDDP. We report that sequential treatment (CDDP followed by Nutlin-3), but not simultaneous treatment, resulted in strong synergism. Combination treatment induced p53's transcriptional activity, resulting in increased mRNA and protein levels of MDM2, p21, PUMA and BAX. In addition we report the induction of a strong p53 dependent apoptotic response and induction of G2/M cell cycle arrest. The strongest synergistic effect was observed at low doses of both CDDP and Nutlin-3, which could result in fewer (off-target) side effects while maintaining a strong cytotoxic effect. Our results indicate a promising preclinical potential, emphasizing the importance of the applied treatment scheme and the presence of wild type p53 for the combination of CDDP and Nutlin-3. PMID:26125230

  8. Pax3 stimulates p53 ubiquitination and degradation independent of transcription.

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    Xiao Dan Wang

    Full Text Available Pax3 is a developmental transcription factor that is required for neural tube and neural crest development. We previously showed that inactivating the p53 tumor suppressor protein prevents neural tube and cardiac neural crest defects in Pax3-mutant mouse embryos. This demonstrates that Pax3 regulates these processes by blocking p53 function. Here we investigated the mechanism by which Pax3 blocks p53 function.We employed murine embryonic stem cell (ESC-derived neuronal precursors as a cell culture model of embryonic neuroepithelium or neural crest. Pax3 reduced p53 protein stability, but had no effect on p53 mRNA levels or the rate of p53 synthesis. Full length Pax3 as well as fragments that contained either the DNA-binding paired box or the homeodomain, expressed as GST or FLAG fusion proteins, physically associated with p53 and Mdm2 both in vitro and in vivo. In contrast, Splotch Pax3, which causes neural tube and neural crest defects in homozygous embryos, bound weakly, or not at all, to p53 or Mdm2. The paired domain and homeodomain each stimulated Mdm2-mediated ubiquitination of p53 and p53 degradation in the absence of the Pax3 transcription regulatory domains, whereas Splotch Pax3 did not stimulate p53 ubiquitination or degradation.Pax3 inactivates p53 function by stimulating its ubiquitination and degradation. This process utilizes the Pax3 paired domain and homeodomain but is independent of DNA-binding and transcription regulation. Because inactivating p53 is the only required Pax3 function during neural tube closure and cardiac neural crest development, and inactivating p53 does not require Pax3-dependent transcription regulation, this indicates that Pax3 is not required to function as a transcription factor during neural tube closure and cardiac neural crest development. These findings further suggest novel explanations for PAX3 functions in human diseases, such as in neural crest-derived cancers and Waardenburg syndrome types 1 and 3.

  9. Divergent evolution of human p53 binding sites: cell cycle versus apoptosis.

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    Monica M Horvath

    2007-07-01

    Full Text Available The p53 tumor suppressor is a sequence-specific pleiotropic transcription factor that coordinates cellular responses to DNA damage and stress, initiating cell-cycle arrest or triggering apoptosis. Although the human p53 binding site sequence (or response element [RE] is well characterized, some genes have consensus-poor REs that are nevertheless both necessary and sufficient for transactivation by p53. Identification of new functional gene regulatory elements under these conditions is problematic, and evolutionary conservation is often employed. We evaluated the comparative genomics approach for assessing evolutionary conservation of putative binding sites by examining conservation of 83 experimentally validated human p53 REs against mouse, rat, rabbit, and dog genomes and detected pronounced conservation differences among p53 REs and p53-regulated pathways. Bona fide NRF2 (nuclear factor [erythroid-derived 2]-like 2 nuclear factor and NFkappaB (nuclear factor of kappa light chain gene enhancer in B cells binding sites, which direct oxidative stress and innate immunity responses, were used as controls, and both exhibited high interspecific conservation. Surprisingly, the average p53 RE was not significantly more conserved than background genomic sequence, and p53 REs in apoptosis genes as a group showed very little conservation. The common bioinformatics practice of filtering RE predictions by 80% rodent sequence identity would not only give a false positive rate of approximately 19%, but miss up to 57% of true p53 REs. Examination of interspecific DNA base substitutions as a function of position in the p53 consensus sequence reveals an unexpected excess of diversity in apoptosis-regulating REs versus cell-cycle controlling REs (rodent comparisons: p < 1.0 e-12. While some p53 REs show relatively high levels of conservation, REs in many genes such as BAX, FAS, PCNA, CASP6, SIVA1, and P53AIP1 show little if any homology to rodent sequences. This

  10. p53 and the Viral Connection: Back into the Future ‡

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    Ronit Aloni-Grinstein

    2018-06-01

    Full Text Available The discovery of the tumor suppressor p53, through its interactions with proteins of tumor-promoting viruses, paved the way to the understanding of p53 roles in tumor virology. Over the years, accumulating data suggest that WTp53 is involved in the viral life cycle of non-tumor-promoting viruses as well. These include the influenza virus, smallpox and vaccinia viruses, the Zika virus, West Nile virus, Japanese encephalitis virus, Human Immunodeficiency Virus Type 1, Human herpes simplex virus-1, and more. Viruses have learned to manipulate WTp53 through different strategies to improve their replication and spreading in a stage-specific, bidirectional way. While some viruses require active WTp53 for efficient viral replication, others require reduction/inhibition of WTp53 activity. A better understanding of WTp53 functionality in viral life may offer new future clinical approaches, based on WTp53 manipulation, for viral infections.

  11. AAVPG: A vigilant vector where transgene expression is induced by p53

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    Bajgelman, Marcio C.; Medrano, Ruan F.V.; Carvalho, Anna Carolina P.V.; Strauss, Bryan E., E-mail: bstrauss@usp.br

    2013-12-15

    Using p53 to drive transgene expression from viral vectors may provide on demand expression in response to physiologic stress, such as hypoxia or DNA damage. Here we introduce AAVPG, an adeno-associated viral (AAV) vector where a p53-responsive promoter, termed PG, is used to control transgene expression. In vitro assays show that expression from the AAVPG-luc vector was induced specifically in the presence of functional p53 (1038±202 fold increase, p<0.001). The AAVPG-luc vector was an effective biosensor of p53 activation in response to hypoxia (4.48±0.6 fold increase in the presence of 250 µM CoCl{sub 2}, p<0.001) and biomechanical stress (2.53±0.4 fold increase with stretching, p<0.05). In vivo, the vigilant nature of the AAVPG-luc vector was revealed after treatment of tumor-bearing mice with doxorubicin (pre-treatment, 3.4×10{sup 5}±0.43×10{sup 5} photons/s; post-treatment, 6.6×10{sup 5}±2.1×10{sup 5} photons/s, p<0.05). These results indicate that the AAVPG vector is an interesting option for detecting p53 activity both in vitro and in vivo. - Highlights: • AAV vector where transgene expression is controlled by the tumor suppressor p53. • The new vector, AAVPG, shown to function as a biosensor of p53 activity, in vitro and in vivo. • The p53 activity monitored by the AAVPG vector is relevant to cancer and other diseases. • AAVPG reporter gene expression was activated upon DNA damage, hypoxia and mechanical stress.

  12. p53-Dependent and -Independent Epithelial Integrity: Beyond miRNAs and Metabolic Fluctuations

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    Tsukasa Oikawa

    2018-05-01

    Full Text Available In addition to its classical roles as a tumor suppressor, p53 has also been shown to act as a guardian of epithelial integrity by inducing the microRNAs that target transcriptional factors driving epithelial–mesenchymal transition. On the other hand, the ENCODE project demonstrated an enrichment of putative motifs for the binding of p53 in epithelial-specific enhancers, such as CDH1 (encoding E-cadherin enhancers although its biological significance remained unknown. Recently, we identified two novel modes of epithelial integrity (i.e., maintenance of CDH1 expression: one involves the binding of p53 to a CDH1 enhancer region and the other does not. In the former, the binding of p53 is necessary to maintain permissive histone modifications around the CDH1 transcription start site, whereas in the latter, p53 does not bind to this region nor affect histone modifications. Furthermore, these mechanisms likely coexisted within the same tissue. Thus, the mechanisms involved in epithelial integrity appear to be much more complex than previously thought. In this review, we describe our findings, which may instigate further experimental scrutiny towards understanding the whole picture of epithelial integrity as well as the related complex asymmetrical functions of p53. Such understanding will be important not only for cancer biology but also for the safety of regenerative medicine.

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

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    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.

  14. Substrate Stiffness Influences Doxorubicin-Induced p53 Activation via ROCK2 Expression

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    Takahiro Ebata

    2017-01-01

    Full Text Available The physical properties of the extracellular matrix (ECM, such as stiffness, are involved in the determination of the characteristics of cancer cells, including chemotherapy sensitivity. Resistance to chemotherapy is often linked to dysfunction of tumor suppressor p53; however, it remains elusive whether the ECM microenvironment interferes with p53 activation in cancer cells. Here, we show that, in MCF-7 breast cancer cells, extracellular stiffness influences p53 activation induced by the antitumor drug doxorubicin. Cell growth inhibition by doxorubicin was increased in response to ECM rigidity in a p53-dependent manner. The expression of Rho-associated coiled coil-containing protein kinase (ROCK 2, which induces the activation of myosin II, was significantly higher when cells were cultured on stiffer ECM substrates. Knockdown of ROCK2 expression or pharmacological inhibition of ROCK decreased doxorubicin-induced p53 activation. Our results suggest that a soft ECM causes downregulation of ROCK2 expression, which drives resistance to chemotherapy by repressing p53 activation.

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

    International Nuclear Information System (INIS)

    Yi Fuming; Saha, Abhik; Murakami, Masanao; Kumar, Pankaj; Knight, Jason S.; Cai Qiliang; Choudhuri, Tathagata; Robertson, Erle S.

    2009-01-01

    The p53 tumor suppressor gene is one of the most commonly mutated genes in human cancers and the corresponding encoded protein induces apoptosis or cell-cycle arrest at the G1/S checkpoint in response to DNA damage. To date, previous studies have shown that antigens encoded by human tumor viruses such as SV40 large T antigen, adenovirus E1A and HPV E6 interact with p53 and disrupt its functional activity. In a similar fashion, we now show that EBNA3C, one of the EBV latent antigens essential for the B-cell immortalization in vitro, interacts directly with p53. Additionally, we mapped the interaction of EBNA3C with p53 to the C-terminal DNA-binding and the tetramerization domain of p53, and the region of EBNA3C responsible for binding to p53 was mapped to the N-terminal domain of EBNA3C (residues 130-190), previously shown to interact with a number of important cell-cycle components, specifically SCF Skp2 , cyclin A, and cMyc. Furthermore, we demonstrate that EBNA3C substantially represses the transcriptional activity of p53 in luciferase based reporter assays, and rescues apoptosis induced by ectopic p53 expression in SAOS-2 (p53 -/- ) cells. Interestingly, we also show that the DNA-binding ability of p53 is diminished in the presence of EBNA3C. Thus, the interaction between the p53 and EBNA3C provides new insights into the mechanism(s) by which the EBNA3C oncoprotein can alter cellular gene expression in EBV associated human cancers.

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

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

    2016-03-01

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

  17. Impact of Alu repeats on the evolution of human p53 binding sites

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    Sirotin Michael V

    2011-01-01

    Full Text Available Abstract Background The p53 tumor suppressor protein is involved in a complicated regulatory network, mediating expression of ~1000 human genes. Recent studies have shown that many p53 in vivo binding sites (BSs reside in transposable repeats. The relationship between these BSs and functional p53 response elements (REs remains unknown, however. We sought to understand whether the p53 REs also reside in transposable elements and particularly in the most-abundant Alu repeats. Results We have analyzed ~160 functional p53 REs identified so far and found that 24 of them occur in repeats. More than half of these repeat-associated REs reside in Alu elements. In addition, using a position weight matrix approach, we found ~400,000 potential p53 BSs in Alu elements genome-wide. Importantly, these putative BSs are located in the same regions of Alu repeats as the functional p53 REs - namely, in the vicinity of Boxes A/A' and B of the internal RNA polymerase III promoter. Earlier nucleosome-mapping experiments showed that the Boxes A/A' and B have a different chromatin environment, which is critical for the binding of p53 to DNA. Here, we compare the Alu-residing p53 sites with the corresponding Alu consensus sequences and conclude that the p53 sites likely evolved through two different mechanisms - the sites overlapping with the Boxes A/A' were generated by CG → TG mutations; the other sites apparently pre-existed in the progenitors of several Alu subfamilies, such as AluJo and AluSq. The binding affinity of p53 to the Alu-residing sites generally correlates with the age of Alu subfamilies, so that the strongest sites are embedded in the 'relatively young' Alu repeats. Conclusions The primate-specific Alu repeats play an important role in shaping the p53 regulatory network in the context of chromatin. One of the selective factors responsible for the frequent occurrence of Alu repeats in introns may be related to the p53-mediated regulation of Alu

  18. Abrogation of Gli3 expression suppresses the growth of colon cancer cells via activation of p53

    International Nuclear Information System (INIS)

    Kang, Han Na; Oh, Sang Cheul; Kim, Jun Suk; Yoo, Young A.

    2012-01-01

    p53, the major human tumor suppressor, appears to be related to sonic hedgehog (Shh)–Gli-mediated tumorigenesis. However, the role of p53 in tumor progression by the Shh–Gli signaling pathway is poorly understood. Herein we investigated the critical regulation of Gli3–p53 in tumorigenesis of colon cancer cells and the molecular mechanisms underlying these effects. RT-PCR analysis indicated that the mRNA level of Shh and Gli3 in colon tumor tissues was significantly higher than corresponding normal tissues (P < 0.001). The inhibition of Gli3 by treatment with Gli3 siRNA resulted in a clear decrease in cell proliferation and enhanced the level of expression of p53 proteins compared to treatment with control siRNA. The half-life of p53 was dramatically increased by treatment with Gli3 siRNA. In addition, treatment with MG132 blocked MDM2-mediated p53 ubiquitination and degradation, and led to accumulation of p53 in Gli3 siRNA-overexpressing cells. Importantly, ectopic expression of p53 siRNA reduced the ability of Gli3 siRNA to suppress proliferation of those cells compared with the cells treated with Gli3 siRNA alone. Moreover, Gli3 siRNA sensitized colon cancer cells to treatment with anti-cancer agents (5-FU and bevacizumab). Taken together, our studies demonstrate that loss of Gli3 signaling leads to disruption of the MDM2–p53 interaction and strongly potentiate p53-dependent cell growth inhibition in colon cancer cells, indicating a basis for the rational use of Gli3 antagonists as a novel treatment option for colon cancer.

  19. Genistein inhibits proliferation of colon cancer cells by attenuating a negative effect of epidermal growth factor on tumor suppressor FOXO3 activity

    International Nuclear Information System (INIS)

    Qi, Wentao; Weber, Christopher R; Wasland, Kaarin; Savkovic, Suzana D

    2011-01-01

    Soy consumption is associated with a lower incidence of colon cancer which is believed to be mediated by one of its of components, genistein. Genistein may inhibit cancer progression by inducing apoptosis or inhibiting proliferation, but mechanisms are not well understood. Epidermal growth factor (EGF)-induced proliferation of colon cancer cells plays an important role in colon cancer progression and is mediated by loss of tumor suppressor FOXO3 activity. The aim of this study was to assess if genistein exerts anti-proliferative properties by attenuating the negative effect of EGF on FOXO3 activity. The effect of genistein on proliferation stimulated by EGF-mediated loss of FOXO3 was examined in human colonic cancer HT-29 cells. EGF-induced FOXO3 phosphorylation and translocation were assessed in the presence of genistein. EGF-mediated loss of FOXO3 interactions with p53 (co-immunoprecipitation) and promoter of p27kip1 (ChIP assay) were examined in presence of genistein in cells with mutated p53 (HT-29) and wild type p53 (HCT116). Silencing of p53 determined activity of FOXO3 when it is bound to p53. Genistein inhibited EGF-induced proliferation, while favoring dephosphorylation and nuclear retention of FOXO3 (active state) in colon cancer cells. Upstream of FOXO3, genistein acts via the PI3K/Akt pathway to inhibit EGF-stimulated FOXO3 phosphorylation (i.e. favors active state). Downstream, EGF-induced disassociation of FOXO3 from mutated tumor suppressor p53, but not wild type p53, is inhibited by genistein favoring FOXO3-p53(mut) interactions with the promoter of the cell cycle inhibitor p27kip1 in colon cancer cells. Thus, the FOXO3-p53(mut) complex leads to elevated p27kip1 expression and promotes cell cycle arrest. These novel anti-proliferative mechanisms of genistein suggest a possible role of combining genistein with other chemoreceptive agents for the treatment of colon cancer

  20. Restoration of mp53 to wtp53 by chemical chaperones restores p53-dependent apoptosis after radiotherapy

    International Nuclear Information System (INIS)

    Ohnishi, T.; Asakawa, I.; Tamamoto, T.; Takahashi, A.; Ohnishi, K.

    2003-01-01

    The mutations of many kinds of cancer related genes have been investigated for the predictive assay against cancer therapy by the application of molecular biology. A tumor suppressor gene product of wtp53 plays important roles in cancer suppression through the induction of cell growth arrest, DNA repair or apoptosis. The p53 exerts its function by induction of downstream genes and/or interaction to various proteins. Mutations in the p53 gene (mp53) cause conformational alterations in the p53 protein, the majority of which can no longer induce expression of the downstream genes. The genetic status of p53 gene has been focused as the most important candidate among them for cancer therapy. The gene therapy of p53 has been already applied. We reported that the transfection of mp53 gene increased the radio-, thermo- and chemo-resistance, and depressed apoptosis introduced with them through bax-induction and proteolysis of PARP and caspase-3. From these results, we propose that the gene therapy of wtp53 to p53-deleted cancer cells may be very useful for cancer therapy by the combination with radiotherapy. Even in the case of mp53 cancer cells, we succeeded the restoration of mp53 to wtp53 by glycerol or C-terminal peptide of p53 as chemical chaperones. These experimental progresses might support effective cancer therapy against individual patients bearing with different p53 gene status by the use of the most suitable treatment to them in the near future

  1. The expanding regulatory universe of p53 in gastrointestinal cancer [version 1; referees: 2 approved

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    Andrew Fesler

    2016-04-01

    Full Text Available 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.

  2. Overexpression of p53 activated by small activating RNA suppresses the growth of human prostate cancer cells

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    Ge Q

    2016-01-01

    Full Text Available Qiangqiang Ge,1,* Chenghe Wang,2,* Yajun Ruan,1,* Zhong Chen,1 Jihong Liu,1 Zhangqun Ye1 1Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 2Department of Urology, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: Previous research has reported that a particular double-stranded RNA, named dsP53-285, has the capacity to induce expression of the tumor suppressor gene TP53 in chimpanzee cells by targeting its promoter. Usually, it is the wild-type p53 protein, rather than mutants, which exhibits potent cancer-inhibiting effects. In addition, nonhuman primates, such as chimpanzees, share almost identical genome sequences with humans. This prompted us to speculate whether dsP53-285 can trigger wild-type p53 protein expression in human prostate cancer (PCa cells and consequently suppress cell growth. The human PCa cell lines LNCaP and DU145 were transfected with dsP53-285 for 72 hours. Compared with the dsControl and mock transfection groups, expression of both p53 messenger RNA and p53 protein was significantly enhanced after dsP53-285 transfection, and this enhancement was followed by upregulation of p21, which indirectly indicated that dsP53-285 induced wild-type p53 expression. Moreover, overexpression of wild-type p53 mediated by dsP53-285 downregulated the expression of Cyclin D1 and cyclin-dependent kinase 4/6, thereby inducing PCa cell cycle arrest in G0/G1 phase and then inhibiting cell proliferation and clonogenicity. More importantly, dsP53-285 suppressed PCa cells mainly by modulating wild-type p53 expression. In conclusion, our study provides evidence that dsP53-285 can significantly stimulate wild-type p53 expression in the human PCa cell lines LNCaP and DU145 and can exert potent antitumor effects. Keywords: p53, small activating RNA, prostate

  3. Targeting the p53 Pathway in Ewing Sarcoma

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    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 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. PMID:21197471

  4. P53 activation, a key event of the cellular response to gamma irradiation; L'activation de la proteine p53, un evenement determinant de la reponse cellulaire aux radiations ionisantes

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    Drane, P.; Alvarez, S.; Meiller, A.; May, E. [CEA Fontenay-aux-Roses, Dept. de Radiobiologie et de Radiopathologie, Lab. de Cancerogenese Moleculaire, CNRS, UMR 217, 92 (France)

    2002-03-01

    The tumor suppressor gene p53 encodes a protein whose major function is to protect organisms from proliferation of potentially tumorigenic cells. In normal conditions (unstressed cells), the p53 protein is inert and maintained at low level through its association with the Mdm2 oncogene, causing its translocation from the nucleus into the cytoplasm and its degradation through ubiquitin/proteasome pathway. In response to damaged DNA or to a variety of stresses, p53 accumulates in the nucleus and is activated as a transcriptional trans-activator. Posttranslational modifications of p53 including multi-site phosphorylation and acetylation are the major mechanism of p53 regulation. After exposure to ionising radiation, p53 activation implicates ATM, ATR, Chk2 and Chk1 kinases that phosphorylate the N-terminal domain on Ser15 (ATM and/or ATR), and Ser20 (Chk2 and/or Chk1), causing the dissociation of the p53/Mdm2 complex and thereby the stabilisation of p53. The process initiated by {gamma}-irradiation exposure involves also increased interaction of the p53 N-terminal domain with CBP/p300 and P/CAF leading to acetylation of the distant C-terminal domain at Lys 320, 373 and 382. In addition, the ATM-mediated dephosphorylation of Ser376 creates a fixation site for 14-3-3 protein. Taken together, phosphorylation, acetylation and association with co factors induce the stimulation of p53 transcriptional activity resulting in the expression of a set of genes involved, notably, in cell cycle arrest and apoptosis. This stress-induced p53 pathways lead to one of two outcomes: growth arrest or apoptosis and consequently protects the organism from the genotoxic effects of ionising radiation. (author)

  5. Synthesis and evaluation of modified chalcone based p53 stabilizing agents

    KAUST Repository

    Iftikhar, Sunniya

    2017-07-15

    Tumor suppressor protein p53 induces cell cycle arrest and apoptotic cell death in response to various cellular stresses thereby preventing cancer development. Activation and stabilization of p53 through small organic molecules is, therefore, an attractive approach for the treatment of cancers retaining wild-type p53. In this context, a series of nineteen chalcones with various substitution patterns of functional groups including chloro, fluoro, methoxy, nitro, benzyloxy, 4-methyl benzyloxy was prepared using Claisen-Schmidt condensation. The compounds were characterized using NMR, HRMS, IR and melting points. Evaluation of synthesized compounds against human colorectal (HCT116) and breast (Cal-51) cancer cell lines revealed potent antiproliferative activities. Nine compounds displayed GI50 values in the low micromolar to submicromolar range; for example (E)-1-phenyl-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (SSE14108) showed GI50 of 0.473 ± 0.043 µM against HCT116 cells. Further analysis of these compounds revealed that (E)-3-(4-chlorophenyl)-1-phenylprop-2-en-1-one (SSE14105) and (E)-3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one (SSE14106) caused rapid (4 and 8-hour post-treatment) accumulation of p53 in HCT116 cells similar to its induction by positive control, Nutlin-3. Such activities were absent in 3-(4-methoxyphenyl)propiophenone (SSE14106H2) demonstrating the importance of conjugated ketone for antiproliferative and p53 stabilizing activity of the chalcones. We further evaluated p53 levels in the presence of cycloheximide (CHX) and the results showed that the p53 stabilization was regulated at post-translational level through blockage of its degradation. These chalcones can, therefore, act as fragment leads for further structure optimization to obtain more potent p53 stabilizing agents with enhanced anti-proliferative activities.

  6. Synthesis and evaluation of modified chalcone based p53 stabilizing agents

    KAUST Repository

    Iftikhar, Sunniya; Khan, Sardraz; Bilal, Aishah; Manzoor, Safia; Abdullah, Muhammad; Emwas, Abdul-Hamid M.; Sioud, Salim; Gao, Xin; Chotana, Ghayoor Abbas; Faisal, Amir; Saleem, Rahman Shah Zaib

    2017-01-01

    Tumor suppressor protein p53 induces cell cycle arrest and apoptotic cell death in response to various cellular stresses thereby preventing cancer development. Activation and stabilization of p53 through small organic molecules is, therefore, an attractive approach for the treatment of cancers retaining wild-type p53. In this context, a series of nineteen chalcones with various substitution patterns of functional groups including chloro, fluoro, methoxy, nitro, benzyloxy, 4-methyl benzyloxy was prepared using Claisen-Schmidt condensation. The compounds were characterized using NMR, HRMS, IR and melting points. Evaluation of synthesized compounds against human colorectal (HCT116) and breast (Cal-51) cancer cell lines revealed potent antiproliferative activities. Nine compounds displayed GI50 values in the low micromolar to submicromolar range; for example (E)-1-phenyl-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (SSE14108) showed GI50 of 0.473 ± 0.043 µM against HCT116 cells. Further analysis of these compounds revealed that (E)-3-(4-chlorophenyl)-1-phenylprop-2-en-1-one (SSE14105) and (E)-3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one (SSE14106) caused rapid (4 and 8-hour post-treatment) accumulation of p53 in HCT116 cells similar to its induction by positive control, Nutlin-3. Such activities were absent in 3-(4-methoxyphenyl)propiophenone (SSE14106H2) demonstrating the importance of conjugated ketone for antiproliferative and p53 stabilizing activity of the chalcones. We further evaluated p53 levels in the presence of cycloheximide (CHX) and the results showed that the p53 stabilization was regulated at post-translational level through blockage of its degradation. These chalcones can, therefore, act as fragment leads for further structure optimization to obtain more potent p53 stabilizing agents with enhanced anti-proliferative activities.

  7. Clinical implications of cytosine deletion of exon 5 of P53 gene in non small cell lung cancer patients

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    Rashid Mir

    2016-01-01

    Full Text Available Aim: Lung cancer is considered to be the most common cancer in the world. In humans, about 50% or more cancers have a mutated tumor suppressor p53 gene thereby resulting in accumulation of p53 protein and losing its function to activate the target genes that regulate the cell cycle and apoptosis. Extensive research conducted in murine cancer models with activated p53, loss of p53, or p53 missense mutations have facilitated researchers to understand the role of this key protein. Our study was aimed to evaluate the frequency of cytosine deletion in nonsmall cell lung cancer (NSCLC patients. Methods: One hundred NSCLC patients were genotyped for P53 (exon5, codon168 cytosine deletion leading to loss of its function and activate the target genes by allele-specific polymerase chain reaction. The P53 cytosine deletion was correlated with all the clinicopathological parameters of the patients. Results and Analysis: 59% cases were carrying P53 cytosine deletion. Similarly, the significantly higher incidence of cytosine deletion was reported in current smokers (75% in comparison to exsmoker and nonsmoker. Significantly higher frequency of cytosine deletion was reported in adenocarcinoma (68.08% than squamous cell carcinoma (52.83%. Also, a significant difference was reported between p53 cytosine deletion and metastasis (64.28%. Further, the majority of the cases assessed for response carrying P53 cytosine deletion were found to show faster disease progression. Conclusion: The data suggests that there is a significant association of the P53 exon 5 deletion of cytosine in codon 168 with metastasis and staging of the disease.

  8. Carbon-ion beam irradiation kills X-ray-resistant p53-null cancer cells by inducing mitotic catastrophe.

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    Napapat Amornwichet

    Full Text Available BACKGROUND AND PURPOSE: To understand the mechanisms involved in the strong killing effect of carbon-ion beam irradiation on cancer cells with TP53 tumor suppressor gene deficiencies. MATERIALS AND METHODS: DNA damage responses after carbon-ion beam or X-ray irradiation in isogenic HCT116 colorectal cancer cell lines with and without TP53 (p53+/+ and p53-/-, respectively were analyzed as follows: cell survival by clonogenic assay, cell death modes by morphologic observation of DAPI-stained nuclei, DNA double-strand breaks (DSBs by immunostaining of phosphorylated H2AX (γH2AX, and cell cycle by flow cytometry and immunostaining of Ser10-phosphorylated histone H3. RESULTS: The p53-/- cells were more resistant than the p53+/+ cells to X-ray irradiation, while the sensitivities of the p53+/+ and p53-/- cells to carbon-ion beam irradiation were comparable. X-ray and carbon-ion beam irradiations predominantly induced apoptosis of the p53+/+ cells but not the p53-/- cells. In the p53-/- cells, carbon-ion beam irradiation, but not X-ray irradiation, markedly induced mitotic catastrophe that was associated with premature mitotic entry with harboring long-retained DSBs at 24 h post-irradiation. CONCLUSIONS: Efficient induction of mitotic catastrophe in apoptosis-resistant p53-deficient cells implies a strong cancer cell-killing effect of carbon-ion beam irradiation that is independent of the p53 status, suggesting its biological advantage over X-ray treatment.

  9. A Chimeric Protein PTEN-L-p53 Enters U251 Cells to Repress Proliferation and Invasion.

    Science.gov (United States)

    Xiao, Man; An, Yang; Wang, Fengling; Yao, Chao; Zhang, Chu; Xin, Junfang; Duan, Yongjian; Zhao, Xiaofang; Fang, Na; Ji, Shaoping

    2018-05-23

    PTEN, a well-known tumor suppressor, dephosphorylates PIP3 and inhibits AKT activity. A translational variant of PTEN has been identified and termed PTEN-Long (PTEN-L). The additional 173 amino acids (PTEN-L leader) at the N-terminal constitute a potential signal peptide. Differing from canonical PTEN, PTEN-L is secreted into the extracellular fluid and re-enters recipient cells, playing the similar roles as PTEN in vivo and in vitro. This character confers the PTEN-L a therapeutic ability via directly protein delivering instead of traditional DNA and RNA vector options. In the present study, we employed PTEN-L leader to assemble a fusion protein, PTEN-L-p53, inosculated with the transcriptional regulator TP53, which is another powerful tumor suppressor. We overexpressed PTEN-L-p53 in HEK293T cells and detected it in both the cytoplasm and nucleus. Subsequently, we found that PTEN-L-p53 was secreted outside of the cells and detected in the culture media by immunoblotting. Furthermore, we demonstrated that PTEN-L-p53 freely entered the cells and suppressed the viability of U251cells (p53 R273H , a cell line with p53 R273H-mutation). PTEN-L-p53 is composed of endogenous protein/peptide bearing low immunogenicity, and only the junction region between PTEN-L leader and p53 can act as a new immune epitope. Accordingly, this fusion protein can potentially be used as a therapeutic option for TP53-abnormality cancers. Copyright © 2018. Published by Elsevier Inc.

  10. Dose selenomethionine have radio-protective effect on cell lines with wild type p53?

    International Nuclear Information System (INIS)

    Tsuji, K.; Hagihira, T.; Ohnishi, K.; Ohnishi, T.; Matsumoto, H.

    2003-01-01

    Full text: Selenium compounds are known to have cancer preventive effects. It is reported recently that selenium in the form of selenomethionine (SeMet) can protect cells with wild type p53 from UV-induced cell killing by activating the DNA repair mechanism of p53 tumor suppressor protein via redox factor Ref1 by reducing p53 cysteine residue 275 and 277. In contrast, SeMet has no protective effect on UV-induced cell killing in p53-null cells. If SeMet also has protective effect in cells with wild type p53 on cell killing by photon irradiation, SeMet can be used as normal tissue radio-protector. We examined the effect of SeMet on cell killing by X-ray irradiation in several cell lines with different p53 status at exponentially growing phase. Cell lines used in this experiment were as follows: H1299/neo; human lung cancer cell line of p53 null type tranfected with control vector with no p53, H1299/wp53; wild type p53 transfected counterpart. A172/neo; human glioblastoma cell line with wild type p53, A172/mp53-248; mp53-248 (248-mutant, ARG >TRP) transfected counterpart. SAS/neo; human tongue cancer cell line with wild type p53, and SAS/mp53-248; mp53-248 transfected counterpart. Cells were subcultured at monolayer in D-MEM containing 10% FBS. Survivals of the cells were determined by colony forming ability. Ten-MV linac X-ray was used to irradiate the cells. Exponentially growing cells were incubated with 20μM of SeMet for 15 hours before irradiation. After 24 hours exposure of SeMet, cells were incubated up to two weeks in growth medium for colony formation. Twenty-four hours exposure of 20μM of SeMet had no cytotoxicity on these cell lines. SeMet had no modification effect on cell killing by photon irradiation in H1299/neo, H1299/wp53, SAS/neo, SAS/mp53-248, and A172/mp53-248. On the other hand, SeMet sensitized A172/neo in radiation cell killing. The effects of p53 on interaction of SeMet and photon irradiation differ according to cell lines

  11. Chronic ultraviolet exposure-induced p53 gene alterations in sencar mouse skin carcinogenesis model

    International Nuclear Information System (INIS)

    Tong, Ying; Smith, M.A.; Tucker, S.B.

    1997-01-01

    Alterations of the tumor suppressor gene p53 have been found in ultraviolet radiation (UVR) related human skin cancers and in UVR-induced murine skin tumors. However, links between p53 gene alterations and the stages of carcinogenesis induced by UVR have not been clearly defined. We established a chronic UVR exposure-induced Sencar mouse skin carcinogenesis model to determine the frequency of p53 gene alterations in different stages of carcinogenesis, including UV-exposed skin, papillomas, squamous-cell carcinomas (SCCs), and malignant spindle-cell tumors (SCTs). A high incidence of SCCs and SCTs were found in this model. Positive p53 nuclear staining was found in 10137 (27%) of SCCs and 12124 (50%) of SCTs, but was not detected in normal skin or papillomas. DNA was isolated from 40 paraffin-embedded normal skin, UV-exposed skin, and tumor sections. The p53 gene (exons 5 and 6) was amplified from the sections by using nested polymerase chain reaction (PCR). Subsequent single-strand conformation polymorphism (SSCP) assay and sequencing analysis revealed one point mutation in exon 6 (coden 193, C → A transition) from a UV-exposed skin sample, and seven point mutations in exon 5 (codens 146, 158, 150, 165, and 161, three C → T, two C → A, one C → G, and one A → T transition, respectively) from four SCTs, two SCCs and one UV-exposed skin sample. These experimental results demonstrate that alterations in the p53 gene are frequent events in chronic UV exposure-induced SCCs and later stage SCTs in Sencar mouse skin. 40 refs., 5 figs., 1 tab

  12. Data on the putative role of p53 in breast cancer cell adhesion: Technical information for adhesion assay

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    Kallirroi Voudouri

    2016-12-01

    Full Text Available In this data article, the potential role of p53 tumor suppressor gene (p53 on the attachment ability of MCF-7 breast cancer cells was investigated. In our main article, “IGF-I/ EGF and E2 signaling crosstalk through IGF-IR conduit point affect breast cancer cell adhesion” (K. Voudouri, D. Nikitovic, A. Berdiaki, D. Kletsas, N.K. Karamanos, G.N. Tzanakakis, 2016 [1], we describe the key role of IGF-IR in breast cancer cell adhesion onto fibronectin (FN. p53 tumor suppressor gene is a principal regulator of cancer cell proliferation. Various data have demonstrated an association between p53 and IGF-IR actions on cell growth through its’ putative regulation of IGF-IR expression. According to our performed experiments, p53 does not modify IGF-IR expression and does not affect basal MCF-7 cells adhesion onto FN. Moreover, technical details about the performance of adhesion assay onto the FN substrate were provided.

  13. PML tumor suppressor protein is required for HCV production

    International Nuclear Information System (INIS)

    Kuroki, Misao; Ariumi, Yasuo; Hijikata, Makoto; Ikeda, Masanori; Dansako, Hiromichi; Wakita, Takaji; Shimotohno, Kunitada; Kato, Nobuyuki

    2013-01-01

    Highlights: ► PML tumor suppressor protein is required for HCV production. ► PML is dispensable for HCV RNA replication. ► HCV could not alter formation of PML-NBs. ► INI1 and DDX5, PML-related proteins, are involved in HCV life cycle. -- Abstract: PML tumor suppressor protein, which forms discrete nuclear structures termed PML-nuclear bodies, has been associated with several cellular functions, including cell proliferation, apoptosis and antiviral defense. Recently, it was reported that the HCV core protein colocalizes with PML in PML-NBs and abrogates the PML function through interaction with PML. However, role(s) of PML in HCV life cycle is unknown. To test whether or not PML affects HCV life cycle, we examined the level of secreted HCV core and the infectivity of HCV in the culture supernatants as well as the level of HCV RNA in HuH-7-derived RSc cells, in which HCV-JFH1 can infect and efficiently replicate, stably expressing short hairpin RNA targeted to PML. In this context, the level of secreted HCV core and the infectivity in the supernatants from PML knockdown cells was remarkably reduced, whereas the level of HCV RNA in the PML knockdown cells was not significantly affected in spite of very effective knockdown of PML. In fact, we showed that PML is unrelated to HCV RNA replication using the subgenomic HCV-JFH1 replicon RNA, JRN/3-5B. Furthermore, the infectivity of HCV-like particle in the culture supernatants was significantly reduced in PML knockdown JRN/3-5B cells expressing core to NS2 coding region of HCV-JFH1 genome using the trans-packaging system. Finally, we also demonstrated that INI1 and DDX5, the PML-related proteins, are involved in HCV production. Taken together, these findings suggest that PML is required for HCV production.

  14. P53 Protein Expression in Dental Follicle, Dentigerous Cyst, Odontogenic Keratocyst, and Inflammatory Subtypes of Cysts: An Immunohistochemical Study.

    Science.gov (United States)

    Fatemeh, Mashhadiabbas; Sepideh, Arab; Sara, Bagheri Seyedeh; Nazanin, Mahdavi

    2017-05-01

    An odontogenic keratocyst (OKC) is a developmental odontogenic cyst with aggressive clinical behavior. This cyst shows a different growth mechanism from the more common dentigerous cyst and now has been renamed as a keratocystic odontogenic tumor (KCOT). Inflammation can assist tumor growth via different mechanisms including dysregulation of the p53 gene. This study aims to assess and compare the expression of tumor suppressor gene p53 in inflamed and non-inflamed types of OKC and dentigerous cyst. Immunohistochemical expression of p53 was assessed in 14 cases of dental follicle, 34 cases of OKC (including 18 inflamed OKCs), and 31 cases of dentigerous cyst (including 16 inflamed cysts). The mean percentage of p53 positive cells was 0.7% in dental follicles, 5.4% in non-inflamed OKCs, 17.3% in inflamed OKCs, 1.2% in non-inflamed dentigerous cysts, and 2.2% in inflamed dentigerous cysts. The differences between the groups were statistically significant ( p < 0.050) except for the difference between inflamed and non-inflamed dentigerous cysts, and between dental follicle and non-inflamed dentigerous cyst. The difference in p53 expression in OKC and dentigerous cyst can explain their different growth mechanism and clinical behavior. Inflammation is responsible for the change in behavior of neoplastic epithelium of OKC via p53 overexpression.

  15. P53 Protein Expression in Dental Follicle, Dentigerous Cyst, Odontogenic Keratocyst, and Inflammatory Subtypes of Cysts: An Immunohistochemical Study

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    Mashhadiabbas Fatemeh

    2017-05-01

    Full Text Available Objectives: An odontogenic keratocyst (OKC is a developmental odontogenic cyst with aggressive clinical behavior. This cyst shows a different growth mechanism from the more common dentigerous cyst and now has been renamed as a keratocystic odontogenic tumor (KCOT. Inflammation can assist tumor growth via different mechanisms including dysregulation of the p53 gene. This study aims to assess and compare the expression of tumor suppressor gene p53 in inflamed and non-inflamed types of OKC and dentigerous cyst. Methods: Immunohistochemical expression of p53 was assessed in 14 cases of dental follicle, 34 cases of OKC (including 18 inflamed OKCs, and 31 cases of dentigerous cyst (including 16 inflamed cysts. Results: The mean percentage of p53 positive cells was 0.7% in dental follicles, 5.4% in non-inflamed OKCs, 17.3% in inflamed OKCs, 1.2% in non-inflamed dentigerous cysts, and 2.2% in inflamed dentigerous cysts. The differences between the groups were statistically significant (p < 0.050 except for the difference between inflamed and non-inflamed dentigerous cysts, and between dental follicle and non-inflamed dentigerous cyst. Conclusions: The difference in p53 expression in OKC and dentigerous cyst can explain their different growth mechanism and clinical behavior. Inflammation is responsible for the change in behavior of neoplastic epithelium of OKC via p53 overexpression.

  16. Expression of P-glycoprotein, multidrug resistance-associated protein, glutathione-S-transferase pi and p53 in canine transmissible venereal tumor

    Directory of Open Access Journals (Sweden)

    Daniel G. Gerardi

    2014-01-01

    Full Text Available The overexpression of proteins P-glycoprotein (P-gp, multidrug resistance-associated protein (MRP1, mutant p53, and the enzyme glutathione-S-transferase (GSTpi are related to resistance to chemotherapy in neoplasms. This study evaluated the expression of these markers by immunohistochemistry in two groups of canine TVT, without history of prior chemotherapy (TVT1, n=9 and in TVTs presented unsatisfactory clinical response to vincristine sulfate (TVT2, n=5. The percentage of specimens positively stained for P-gp, MRP1, GSTpi and p53 were, respectively 88.8%, 0%, 44.5% and 22.2% in TVT1 and 80%, 0%, 80% and 0% in TVT2. In TVT1, one specimen presented positive expression for three markers and four specimens for two markers. In TVT2, three specimens expressed P-gp and GSTpi. In conclusion, the canine TVTs studied expressed the four markers evaluated, but just P-gp and GSTpi were significantly expressed, mainly at cytoplasm and cytoplasm and nuclei, respectively, either before chemotherapy as after vincristine sulfate exposure. Future studies are needed to demonstrate the function of these two markers in conferring multidrug resistance (MDR or predict the response to chemotherapy in canine TVT.

  17. Biological and genetic properties of the p53 null preneoplastic mammary epithelium

    Science.gov (United States)

    Medina, Daniel; Kittrell, Frances S.; Shepard, Anne; Stephens, L. Clifton; Jiang, Cheng; Lu, Junxuan; Allred, D. Craig; McCarthy, Maureen; Ullrich, Robert L.

    2002-01-01

    The absence of the tumor suppressor gene p53 confers an increased tumorigenic risk for mammary epithelial cells. In this report, we describe the biological and genetic properties of the p53 null preneoplastic mouse mammary epithelium in a p53 wild-type environment. Mammary epithelium from p53 null mice was transplanted serially into the cleared mammary fat pads of p53 wild-type BALB/c female to develop stable outgrowth lines. The outgrowth lines were transplanted for 10 generations. The outgrowths were ductal in morphology and progressed through ductal hyperplasia and ductal carcinoma in situ before invasive cancer. The preneoplastic outgrowth lines were immortal and exhibited activated telomerase activity. They are estrogen and progesterone receptor-positive, and aneuploid, and had various levels of tumorigenic potential. The biological and genetic properties of these lines are distinct from those found in most hyperplastic alveolar outgrowth lines, the form of mammary preneoplasia occurring in most traditional models of murine mammary tumorigenesis. These results indicate that the preneoplastic cell populations found in this genetically engineered model are similar in biological properties to a subset of precurser lesions found in human breast cancer and provide a unique model to identify secondary events critical for tumorigenicity and invasiveness.

  18. Novel siRNA formulation to effectively knockdown mutant p53 in osteosarcoma.

    Science.gov (United States)

    Kundu, Anup K; Iyer, Swathi V; Chandra, Sruti; Adhikari, Amit S; Iwakuma, Tomoo; Mandal, Tarun K

    2017-01-01

    The tumor suppressor p53 plays a crucial role in the development of osteosarcoma. The primary objective of this study is to develop and optimize lipid based nanoparticle formulations that can carry siRNA and effectively silence mutant p53 in 318-1, a murine osteosarcoma cell line. The nanoparticles were composed of a mixture of two lipids (cholesterol and DOTAP) and either PLGA or PLGA-PEG and prepared by using an EmulsiFlex-B3 high pressure homogenizer. A series of studies that include using different nanoparticles, different amount of siRNAs, cell numbers, incubation time, transfection media volume, and storage temperature was performed to optimize the gene silencing efficiency. Replacement of lipids by PLGA or PLGA-PEG decreased the particle size and overall cytotoxicity. Among all lipid-polymer nanoformulations, nanoparticles with 10% PLGA showed highest mutant p53 knockdown efficiency while maintaining higher cell viability when a nanoparticle to siRNA ratio equal to 6.8:0.66 and 75 nM siRNA was used. With long term storage the mutant p53 knockdown efficiency decreased to a greater extent. This study warrants a future evaluation of this formulation for gene silencing efficiency of mutant p53 in tissue culture and animal models for the treatment of osteosarcoma.

  19. Novel siRNA formulation to effectively knockdown mutant p53 in osteosarcoma.

    Directory of Open Access Journals (Sweden)

    Anup K Kundu

    Full Text Available The tumor suppressor p53 plays a crucial role in the development of osteosarcoma. The primary objective of this study is to develop and optimize lipid based nanoparticle formulations that can carry siRNA and effectively silence mutant p53 in 318-1, a murine osteosarcoma cell line.The nanoparticles were composed of a mixture of two lipids (cholesterol and DOTAP and either PLGA or PLGA-PEG and prepared by using an EmulsiFlex-B3 high pressure homogenizer. A series of studies that include using different nanoparticles, different amount of siRNAs, cell numbers, incubation time, transfection media volume, and storage temperature was performed to optimize the gene silencing efficiency.Replacement of lipids by PLGA or PLGA-PEG decreased the particle size and overall cytotoxicity. Among all lipid-polymer nanoformulations, nanoparticles with 10% PLGA showed highest mutant p53 knockdown efficiency while maintaining higher cell viability when a nanoparticle to siRNA ratio equal to 6.8:0.66 and 75 nM siRNA was used. With long term storage the mutant p53 knockdown efficiency decreased to a greater extent.This study warrants a future evaluation of this formulation for gene silencing efficiency of mutant p53 in tissue culture and animal models for the treatment of osteosarcoma.

  20. Ribosomal stress induces L11- and p53-dependent apoptosis in mouse pluripotent stem cells.

    Science.gov (United States)

    Morgado-Palacin, Lucia; Llanos, Susana; Serrano, Manuel

    2012-02-01

    Ribosome biogenesis is the most demanding energetic process in proliferating cells and it is emerging as a critical sensor of cellular homeostasis. Upon disturbance of ribosome biogenesis, specific free ribosomal proteins, most notably L11, bind and inhibit Mdm2, resulting in activation of the tumor suppressor p53. This pathway has been characterized in somatic and cancer cells, but its function in embryonic pluripotent cells has remained unexplored. Here, we show that treatment with low doses of Actinomycin D or depletion of ribosomal protein L37, two well-established inducers of ribosomal stress, activate p53 in an L11-dependent manner in mouse embryonic stem cells (ESCs) and in induced pluripotent stem cells (iPSCs). Activation of p53 results in transcriptional induction of p53 targets, including p21, Mdm2, Pidd, Puma, Noxa and Bax. Finally, ribosomal stress elicits L11- and p53-dependent apoptosis in ESCs/iPSCs. These results extend to pluripotent cells the functionality of the ribosomal stress pathway and we speculate that this could be a relevant cellular checkpoint during early embryogenesis.

  1. p53 dependent apoptotic cell death induces embryonic malformation in Carassius auratus under chronic hypoxia.

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    Paramita Banerjee Sawant

    Full Text Available Hypoxia is a global phenomenon affecting recruitment as well as the embryonic development of aquatic fauna. The present study depicts hypoxia induced disruption of the intrinsic pathway of programmed cell death (PCD, leading to embryonic malformation in the goldfish, Carrasius auratus. Constant hypoxia induced the early expression of pro-apoptotic/tumor suppressor p53 and concomitant expression of the cell death molecule, caspase-3, leading to high level of DNA damage and cell death in hypoxic embryos, as compared to normoxic ones. As a result, the former showed delayed 4 and 64 celled stages and a delay in appearance of epiboly stage. Expression of p53 efficiently switched off expression of the anti-apoptotic Bcl-2 during the initial 12 hours post fertilization (hpf and caused embryonic cell death. However, after 12 hours, simultaneous downregulation of p53 and Caspase-3 and exponential increase of Bcl-2, caused uncontrolled cell proliferation and prevented essential programmed cell death (PCD, ultimately resulting in significant (p<0.05 embryonic malformation up to 144 hpf. Evidences suggest that uncontrolled cell proliferation after 12 hpf may have been due to downregulation of p53 abundance, which in turn has an influence on upregulation of anti-apoptotic Bcl-2. Therefore, we have been able to show for the first time and propose that hypoxia induced downregulation of p53 beyond 12 hpf, disrupts PCD and leads to failure in normal differentiation, causing malformation in gold fish embryos.

  2. Enhanced p53 gene transfer to human ovarian cancer cells using the cationic nonviral vector, DDC.

    Science.gov (United States)

    Kim, Chong-Kook; Choi, Eun-Jeong; Choi, Sung-Hee; Park, Jeong-Sook; Haider, Khawaja Hasnain; Ahn, Woong Shick

    2003-08-01

    Previously we have formulated a new cationic liposome, DDC, composed of dioleoyltrimethylamino propane (DOTAP), 1,2-dioeoyl-3-phosphophatidylethanolamine (DOPE), and cholesterol (Chol), and it efficiently delivered plasmid DNA into ovarian cancer cells. Mutations in the p53 tumor suppressor gene are the most common molecular genetic abnormalities to be described in ovarian cancer. However, there has been so far no report of nonviral vector-mediated p53 gene deliveries in ovarian cancer. In this study, wild-type p53 DNA was transfected into the ovarian cancer cells, using the DDC as a nonviral vector and the expression and activity of p53 gene were evaluated both in vitro and in vivo. DDC liposomes were prepared by mixing DOTAP:DOPE:Chol in a 1:0.7:0.3 molar ratio using the extrusion method. Plasmid DNA (pp53-EGFP) and DDC complexes were transfected into ovarian carcinoma cells (OVCAR-3 cells) and gene expression was determined by reverse transcription-polymerase chain reaction and Western blot analysis. The cellular growth inhibition and apoptosis of DDC-mediated p53 transfection were assessed by trypan blue exclusion assay and annexin-V staining, respectively. The OVCAR-3 cells treated with DDC/pp53-EGFP complexes were inoculated into female balb/c nude mice and tumor growth was observed. The transfection of liposome-complexed p53 gene resulted in a high level of wild-type p53 mRNA and protein expressions in OVCAR-3 cells. In vitro cell growth assay showed growth inhibition of cancer cells transfected with DDC/pp53-EGFP complexes compared with the control cells. The reestablishment of wild-type p53 function in ovarian cancer cells restored the apoptotic pathway. Following the inoculation of DDC/pp53-EGFP complexes, the volumes of tumors in nude mice were significantly reduced more than 60% compared to the control group. The DDC-mediated p53 DNA delivery may have the potential for clinical application as nonviral vector-mediated ovarian cancer therapy due to its

  3. Human glioblastoma multiforme: p53 reactivation by a novel MDM2 inhibitor.

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    Barbara Costa

    Full Text Available Cancer development and chemo-resistance are often due to impaired functioning of the p53 tumor suppressor through genetic mutation or sequestration by other proteins. In glioblastoma multiforme (GBM, p53 availability is frequently reduced because it binds to the Murine Double Minute-2 (MDM2 oncoprotein, which accumulates at high concentrations in tumor cells. The use of MDM2 inhibitors that interfere with the binding of p53 and MDM2 has become a valid approach to inhibit cell growth in a number of cancers; however little is known about the efficacy of these inhibitors in GBM. We report that a new small-molecule inhibitor of MDM2 with a spirooxoindolepyrrolidine core structure, named ISA27, effectively reactivated p53 function and inhibited human GBM cell growth in vitro by inducing cell cycle arrest and apoptosis. In immunoincompetent BALB/c nude mice bearing a human GBM xenograft, the administration of ISA27 in vivo activated p53, inhibited cell proliferation and induced apoptosis in tumor tissue. Significantly, ISA27 was non-toxic in an in vitro normal human cell model and an in vivo mouse model. ISA27 administration in combination with temozolomide (TMZ produced a synergistic inhibitory effect on GBM cell viability in vitro, suggesting the possibility of lowering the dose of TMZ used in the treatment of GBM. In conclusion, our data show that ISA27 releases the powerful antitumor capacities of p53 in GBM cells. The use of this MDM2 inhibitor could become a novel therapy for the treatment of GBM patients.

  4. DNA double strand break repair is enhanced by P53 following induction by DNA damage and is dependent on the C-terminal domain of P53

    International Nuclear Information System (INIS)

    Wei Tang; Powell, Simon N.

    1996-01-01

    Purpose: The tumor suppressor gene p53 can mediate cell cycle arrest or apoptosis in response to DNA damage. Accumulating evidence suggests that it may also directly or indirectly influence the DNA repair machinery. In the present study, we investigated whether p53, induced by DNA damage, could enhance the rejoining of double-strand DNA breaks. Materials and Methods: DNA double-strand breaks (dsb) were made by restriction enzyme digestion of a plasmid, between a promoter and a 'reporter' gene: luciferase (LUC) or chloramphenicol acetyl-transferase (CAT). Linear or circular plasmid DNA (LUC or CAT) was co-transfected with circular β-Gal plasmid (to normalize for uptake) into mouse embryonic fibroblasts genetically matched to be (+/+) or (-/-) for p53. Their ability to rejoin linearized plasmid was measured by the luciferase or CAT activity detected in rescued plasmids. The activity detected in cells transfected with linear plasmid was scored relative to the activity detected in cells transfected with circular plasmid. Results: Ionizing radiation (IR, 2 Gy) enhanced the dsb repair activity in wild type p53 cells; however, p53 null cells lose this effect, indicating that the enhancement of dsb repair was p53-dependent. REF cells with dominant-negative mutant p53 showed a similar induction compared with the parental REF cells with wild-type p53. This ala-143 mutant p53 prevents cell cycle arrest and transactivation of p21 WAF1/cip1) following IR, indicating that the p53-dependent enhancement of DNA repair is distinct from transactivation. Immortalized murine embryonic fibroblasts, 10(1)VasK1 cells, which express p53 cDNA encoding a temperature-sensitive mutant in the DNA sequence specific binding domain (ala135 to val135) with an alternatively spliced C-terminal domain (ASp53: amino-acids 360-381) and, 10(1)Val5 cells, which express the normal spliced p53 (NSp53) with the same temperature-sensitive mutant were compared. It was found that 10(1)VasK1 cells showed no DNA

  5. 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

  6. Immunohistochemical study of p53 and proliferating cell nuclear antigen expression in odontogenic keratocyst and periapical cyst

    Directory of Open Access Journals (Sweden)

    Thara Purath Sajeevan

    2014-01-01

    Full Text Available Introduction: p53 protein is a product of p53 gene, which is now classified as a tumor suppressor gene. The gene is a frequent target for mutation, being seen as a common step in the pathogenesis of many human cancers. Proliferating cell nuclear antigen (PCNA is an auxiliary protein of DNA polymerase delta and plays a critical role in initiation of cell proliferation. Aim: The aim of this study is to assess and compare the expression of p53 and PCNA in lining epithelium of odontogenic keratocyst (OKC and periapical cyst (PA. Materials and Methods: A total of 20 cases comprising 10 OKC and 10 PA were included in retrospective study. Three paraffin section of 4 μm were cut, one was used for routine hematoxylin and eosin stain, while the other two were used for immunohistochemistry. Statistical analysis was performed using Chi-square test. Results: The level of staining and intensity were assessed in all these cases. OKC showed PCNA expression in all cases (100%, whereas in perapical cyst only 60% of cases exhibited PCNA staining. (1 OKC showed p53 expression in 6 cases (60% whereas in PA only 10% of the cases exhibited p53 staining. Chi-square test showed PCNA staining intensity was more significant than p53 in OKC. (2 The staining intensity of PA using p53, PCNA revealed that PCNA stating intensity was more significant than p53. Conclusion: OKC shows significant proliferative activity than PA using PCNA and p53. PCNA staining was more intense when compared with p53 in both OKC and PA.

  7. ATM-dependent phosphorylation of Mdm2 on serine 395: role in p53 activation by DNA damage

    Science.gov (United States)

    Maya, Ruth; Balass, Moshe; Kim, Seong-Tae; Shkedy, Dganit; Leal, Juan-Fernando Martinez; Shifman, Ohad; Moas, Miri; Buschmann, Thomas; Ronai, Ze'ev; Shiloh, Yosef; Kastan, Michael B.; Katzir, Ephraim; Oren, Moshe

    2001-01-01

    The p53 tumor suppressor protein, a key regulator of cellular responses to genotoxic stress, is stabilized and activated after DNA damage. The rapid activation of p53 by ionizing radiation and radiomimetic agents is largely dependent on the ATM kinase. p53 is phosphorylated by ATM shortly after DNA damage, resulting in enhanced stability and activity of p53. The Mdm2 oncoprotein is a pivotal negative regulator of p53. In response to ionizing radiation and radiomimetic drugs, Mdm2 undergoes rapid ATM-dependent phosphorylation prior to p53 accumulation. This results in a decrease in its reactivity with the 2A10 monoclonal antibody. Phage display analysis identified a consensus 2A10 recognition sequence, possessing the core motif DYS. Unexpectedly, this motif appears twice within the human Mdm2 molecule, at positions corresponding to residues 258–260 and 393–395. Both putative 2A10 epitopes are highly conserved and encompass potential phosphorylation sites. Serine 395, residing within the carboxy-terminal 2A10 epitope, is the major target on Mdm2 for phosphorylation by ATM in vitro. Mutational analysis supports the conclusion that Mdm2 undergoes ATM-dependent phosphorylation on serine 395 in vivo in response to DNA damage. The data further suggests that phosphorylated Mdm2 may be less capable of promoting the nucleo-cytoplasmic shuttling of p53 and its subsequent degradation, thereby enabling p53 accumulation. Our findings imply that activation of p53 by DNA damage is achieved, in part, through attenuation of the p53-inhibitory potential of Mdm2. PMID:11331603

  8. Immunohistochemical study of p53 and proliferating cell nuclear antigen expression in odontogenic keratocyst and periapical cyst.

    Science.gov (United States)

    Sajeevan, Thara Purath; Saraswathi, Tillai Rajasekaran; Ranganathan, Kannan; Joshua, Elizabeth; Rao, Uma Devi K

    2014-07-01

    p53 protein is a product of p53 gene, which is now classified as a tumor suppressor gene. The gene is a frequent target for mutation, being seen as a common step in the pathogenesis of many human cancers. Proliferating cell nuclear antigen (PCNA) is an auxiliary protein of DNA polymerase delta and plays a critical role in initiation of cell proliferation. The aim of this study is to assess and compare the expression of p53 and PCNA in lining epithelium of odontogenic keratocyst (OKC) and periapical cyst (PA). A total of 20 cases comprising 10 OKC and 10 PA were included in retrospective study. Three paraffin section of 4 μm were cut, one was used for routine hematoxylin and eosin stain, while the other two were used for immunohistochemistry. Statistical analysis was performed using Chi-square test. The level of staining and intensity were assessed in all these cases. OKC showed PCNA expression in all cases (100%), whereas in perapical cyst only 60% of cases exhibited PCNA staining. (1) OKC showed p53 expression in 6 cases (60%) whereas in PA only 10% of the cases exhibited p53 staining. Chi-square test showed PCNA staining intensity was more significant than p53 in OKC. (2) The staining intensity of PA using p53, PCNA revealed that PCNA stating intensity was more significant than p53. OKC shows significant proliferative activity than PA using PCNA and p53. PCNA staining was more intense when compared with p53 in both OKC and PA.

  9. Cell size checkpoint control by the retinoblastoma tumor suppressor pathway.

    Science.gov (United States)

    Fang, Su-Chiung; de los Reyes, Chris; Umen, James G

    2006-10-13

    Size control is essential for all proliferating cells, and is thought to be regulated by checkpoints that couple cell size to cell cycle progression. The aberrant cell-size phenotypes caused by mutations in the retinoblastoma (RB) tumor suppressor pathway are consistent with a role in size checkpoint control, but indirect effects on size caused by altered cell cycle kinetics are difficult to rule out. The multiple fission cell cycle of the unicellular alga Chlamydomonas reinhardtii uncouples growth from division, allowing direct assessment of the relationship between size phenotypes and checkpoint function. Mutations in the C. reinhardtii RB homolog encoded by MAT3 cause supernumerous cell divisions and small cells, suggesting a role for MAT3 in size control. We identified suppressors of an mat3 null allele that had recessive mutations in DP1 or dominant mutations in E2F1, loci encoding homologs of a heterodimeric transcription factor that is targeted by RB-related proteins. Significantly, we determined that the dp1 and e2f1 phenotypes were caused by defects in size checkpoint control and were not due to a lengthened cell cycle. Despite their cell division defects, mat3, dp1, and e2f1 mutants showed almost no changes in periodic transcription of genes induced during S phase and mitosis, many of which are conserved targets of the RB pathway. Conversely, we found that regulation of cell size was unaffected when S phase and mitotic transcription were inhibited. Our data provide direct evidence that the RB pathway mediates cell size checkpoint control and suggest that such control is not directly coupled to the magnitude of periodic cell cycle transcription.

  10. Tumor Suppressor Function of CYLD in Nonmelanoma Skin Cancer

    Directory of Open Access Journals (Sweden)

    K. C. Masoumi

    2011-01-01

    Full Text Available Ubiquitin and ubiquitin-related proteins posttranslationally modify substrates, and thereby alter the functions of their targets. The ubiquitination process is involved in various physiological responses, and dysregulation of components of the ubiquitin system has been linked to many diseases including skin cancer. The ubiquitin pathways activated among skin cancers are highly diverse and may reflect the various characteristics of the cancer type. Basal cell carcinoma and squamous cell carcinoma, the most common types of human skin cancer, are instances where the involvement of the deubiquitination enzyme CYLD has been recently highlighted. In basal cell carcinoma, the tumor suppressor protein CYLD is repressed at the transcriptional levels through hedgehog signaling pathway. Downregulation of CYLD in basal cell carcinoma was also shown to interfere with TrkC expression and signaling, thereby promoting cancer progression. By contrast, the level of CYLD is unchanged in squamous cell carcinoma, instead, catalytic inactivation of CYLD in the skin has been linked to the development of squamous cell carcinoma. This paper will focus on the current knowledge that links CYLD to nonmelanoma skin cancers and will explore recent insights regarding CYLD regulation of NF-κB and hedgehog signaling during the development and progression of these types of human tumors.

  11. Tumor Suppressor Function of CYLD in Non melanoma Skin Cancer

    International Nuclear Information System (INIS)

    Masoumi, K. C.; Hallgren, G. S.; Massoumi, R.

    2011-01-01

    Ubiquitin and ubiquitin-related proteins post translationally modify substrates, and thereby alter the functions of their targets. The ubiquitination process is involved in various physiological responses, and dysregulation of components of the ubiquitin system has been linked to many diseases including skin cancer. The ubiquitin pathways activated among skin cancers are highly diverse and may reflect the various characteristics of the cancer type. Basal cell carcinoma and squamous cell carcinoma, the most common types of human skin cancer, are instances where the involvement of the deubiquitination enzyme CYLD has been recently highlighted. In basal cell carcinoma, the tumor suppressor protein CYLD is repressed at the transcriptional levels through hedgehog signaling pathway. Downregulation of CYLD in basal cell carcinoma was also shown to interfere with TrkC expression and signaling, thereby promoting cancer progression. By contrast, the level of CYLD is unchanged in squamous cell carcinoma, instead, catalytic inactivation of CYLD in the skin has been linked to the development of squamous cell carcinoma. This paper will focus on the current knowledge that links CYLD to non melanoma skin cancers and will explore recent insights regarding CYLD regulation of NF-κB and hedgehog signaling during the development and progression of these types of human tumors.

  12. SIRT3: Oncogene and Tumor Suppressor in Cancer

    Directory of Open Access Journals (Sweden)

    Margalida Torrens-Mas

    2017-07-01

    Full Text Available Sirtuin 3 (SIRT3, the major deacetylase in mitochondria, plays a crucial role in modulating oxygen reactive species (ROS and limiting the oxidative damage in cellular components. SIRT3 targets different enzymes which regulate mitochondrial metabolism and participate in ROS detoxification, such as the complexes of the respiratory chain, the isocitrate dehydrogenase, or the manganese superoxide dismutase. Thus, SIRT3 activity is essential in maintaining mitochondria homeostasis and has recently received great attention, as it is considered a fidelity protein for mitochondrial function. In some types of cancer, SIRT3 functions as a tumoral promoter, since it keeps ROS levels under a certain threshold compatible with cell viability and proliferation. On the contrary, other studies describe SIRT3 as a tumoral suppressor, as SIRT3 could trigger cell death under stress conditions. Thus, SIRT3 could have a dual role in cancer. In this regard, modulation of SIRT3 activity could be a new target to develop more personalized therapies against cancer.

  13. Phytochemical Compositions of Immature Wheat Bran, and Its Antioxidant Capacity, Cell Growth Inhibition, and Apoptosis Induction through Tumor Suppressor Gene

    Directory of Open Access Journals (Sweden)

    Mi Jeong Kim

    2016-09-01

    Full Text Available The purpose of this study was to investigate the phytochemical compositions and antioxidant capacity, cell growth inhibition, and apoptosis induction in extracts of immature wheat bran. Immature wheat bran (IWB was obtained from immature wheat harvested 10 days earlier than mature wheat. The phytochemical compositions of bran extract samples were analyzed by ultra-high performance liquid chromatography. The total ferulic acid (3.09 mg/g and p-coumaric acid (75 µg/g in IWB were significantly higher than in mature wheat bran (MWB, ferulic acid: 1.79 mg/g; p-coumaric acid: 55 µg/g. The oxygen radical absorbance capacity (ORAC: 327 µM Trolox equivalents (TE/g and cellular antioxidant activity (CAA: 4.59 µM Quercetin equivalents (QE/g of the IWB were higher than those of the MWB (ORAC: 281 µM TE/g; CAA: 0.63 µM QE/g. When assessing cell proliferation, the IWB extracts resulted in the lowest EC50 values against HT-29 (18.9 mg/mL, Caco-2 (7.74 mg/mL, and HeLa cells (8.17 mg/mL among bran extract samples. Additionally, the IWB extracts increased the gene expression of p53 and PTEN (tumor suppressor genes in HT-29 cells, indicating inhibited cell growth and induced apoptosis through tumor suppressor genes.

  14. Loss of Maspin Expression in Bladder Cancer: Its Relationship with p53 and Clinico pathological Parameters

    International Nuclear Information System (INIS)

    Abd El-Maqsoud, N.M.R.; Tawfiek, E.R.

    2010-01-01

    Maspin (mammary serine protease inhibitor) is a member of the serpin super family of protease inhibitors and is known to have tumor-suppressor function in breast and prostate cancers, acting at the level of tumor invasion and metastasis. However, there have been no published data regarding the role of Maspin in squamous cell carcinoma (SCC) and transitional cell carcinoma (TCC) of urinary bladder. Patients and Methods: We have evaluated the immunohistochemical expression of Maspin and p53 in a series of 134 bladder cancer patients (56 SCC and 78 TCC) and the interrelationship between Clinico pathological features and Maspin and p53 expression. Results: There was positive Maspin expression in 53.7% in all cases. In TCC, expression was found in 48/78 cases (61.5%). High Maspin expression was found in low grade (p<0.001) and advanced stage (p=0.02). In SCC, expression was found in 24/56 (42.8%). There was a statistically significant association between lost Maspin expression and grading (p=0.001). No correlation was found between Maspin expression and other Clinico pathological parameters including gender, clinical stage and Bilharzial infestation. These results indicated that Maspin expression might predict a better prognosis for bladder carcinoma. Also Maspin probably could play a role in tumor progression. p53 was positive in 70 cases (52.2%) of all patients evaluated. In TCC, it was positive in 36/78 cases (46.1%) and correlated with high grade (p=0.01) and advanced stage (p=0.01). In SCC, it was positive in 34/56 cases (60.7%). There was a statistically significant association between p53 expression and high grade (p=0.01) and advanced stage (p=0.01). There was an inverse correlation between the Maspin and p53 expression in TCC and SCC of bladder cancer. We found no significant association between both Maspin and p53 expression and bilharziasis in TCC and SCC; this indicated that Maspin and p53 expression could be prognostic factors in both bilharzial and non

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

    International Nuclear Information System (INIS)

    Oh, Sang Taek; Cho, Mun Ju; Gwak, Jung Sug; Ryu, Min Jung; Song, Jie Young; Yun, Yeon Sook

    2009-01-01

    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

  16. TAF6delta controls apoptosis and gene expression in the absence of p53.

    Directory of Open Access Journals (Sweden)

    Emmanuelle Wilhelm

    Full Text Available BACKGROUND: Life and death decisions of metazoan cells hinge on the balance between the expression of pro- versus anti-apoptotic gene products. The general RNA polymerase II transcription factor, TFIID, plays a central role in the regulation of gene expression through its core promoter recognition and co-activator functions. The core TFIID subunit TAF6 acts in vitro as an essential co-activator of transcription for the p53 tumor suppressor protein. We previously identified a splice variant of TAF6, termed TAF6delta that can be induced during apoptosis. METHODOLOGY/PRINCIPAL FINDINGS: To elucidate the impact of TAF6delta on cell death and gene expression, we have employed modified antisense oligonucleotides to enforce expression of endogenous TAF6delta. The induction of endogenous TAF6delta triggered apoptosis in tumor cell lines, including cells devoid of p53. Microarray experiments revealed that TAF6delta activates gene expression independently of cellular p53 status. CONCLUSIONS: Our data define TAF6delta as a pivotal node in a signaling pathway that controls gene expression programs and apoptosis in the absence of p53.

  17. 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.

  18. NBPF1, a tumor suppressor candidate in neuroblastoma, exerts growth inhibitory effects by inducing a G1 cell cycle arrest

    International Nuclear Information System (INIS)

    Andries, Vanessa; Vandepoele, Karl; Staes, Katrien; Berx, Geert; Bogaert, Pieter; Van Isterdael, Gert; Ginneberge, Daisy; Parthoens, Eef; Vandenbussche, Jonathan; Gevaert, Kris; Roy, Frans van

    2015-01-01

    NBPF1 (Neuroblastoma Breakpoint Family, member 1) was originally identified in a neuroblastoma patient on the basis of its disruption by a chromosomal translocation t(1;17)(p36.2;q11.2). Considering this genetic defect and the frequent genomic alterations of the NBPF1 locus in several cancer types, we hypothesized that NBPF1 is a tumor suppressor. Decreased expression of NBPF1 in neuroblastoma cell lines with loss of 1p36 heterozygosity and the marked decrease of anchorage-independent clonal growth of DLD1 colorectal carcinoma cells with induced NBPF1 expression further suggest that NBPF1 functions as tumor suppressor. However, little is known about the mechanisms involved. Expression of NBPF was analyzed in human skin and human cervix by immunohistochemistry. The effects of NBPF1 on the cell cycle were evaluated by flow cytometry. We investigated by real-time quantitative RT-PCR the expression profile of a panel of genes important in cell cycle regulation. Protein levels of CDKN1A-encoded p21 CIP1/WAF1 were determined by western blotting and the importance of p53 was shown by immunofluorescence and by a loss-of-function approach. LC-MS/MS analysis was used to investigate the proteome of DLD1 colon cancer cells with induced NBPF1 expression. Possible biological interactions between the differentially regulated proteins were investigated with the Ingenuity Pathway Analysis tool. We show that NBPF is expressed in the non-proliferative suprabasal layers of squamous stratified epithelia of human skin and cervix. Forced expression of NBPF1 in HEK293T cells resulted in a G1 cell cycle arrest that was accompanied by upregulation of the cyclin-dependent kinase inhibitor p21 CIP1/WAF1 in a p53-dependent manner. Additionally, forced expression of NBPF1 in two p53-mutant neuroblastoma cell lines also resulted in a G1 cell cycle arrest and CDKN1A upregulation. However, CDKN1A upregulation by NBPF1 was not observed in the DLD1 cells, which demonstrates that NBPF1 exerts cell

  19. Expression of the p16{sup INK4a} tumor suppressor gene in rodent lung tumors

    Energy Technology Data Exchange (ETDEWEB)

    Swafford, D.S.; Tesfaigzi, J.; Belinsky, S.A.

    1995-12-01

    Aberrations on the short arm of chromosome 9 are among the earliest genetic changes in human cancer. p16{sup INK4a} is a candidate tumor suppressor gene that lies within human 9p21, a chromosome region associated with frequent loss of heterozygosity in human lung tumors. The p16{sup INK4a} protein functions as an inhibitor of cyclin D{sub 1}-dependent kinases that phosphorylate the retinoblastoma (Rb) tumor suppressor gene product enabling cell-cycle progression. Thus, overexpression of cyclin D{sub 1}, mutation of cyclin-dependent kinase genes, or loss of p16{sup INK4a} function, can all result in functional inactivation of Rb. Inactivation of Rb by mutation or deletion can result in an increase in p16{sup INK4a} transcription, suggesting that an increased p16{sup INK4a} expression in a tumor cell signals dysfunction of the pathway. The p16{sup (INK4a)} gene, unlike some tumor suppressor genes, is rarely inactivated by mutation. Instead, the expression of this gene is suppressed in some human cancers by hypermethylation of the CpG island within the first exon or by homozygous deletion: 686. Chromosome losses have been observed at 9p21 syntenic loci in tumors of the mouse and rat, two species often used as animal models for pulmonary carcinogenesis. Expression of p16{sup INK4a} is lost in some mouse tumor cell lines, often due to homozygous deletion. These observations indicate that p16{sup INK4a} dysfunction may play a role in the development of neoplasia in rodents as well as humans. The purpose of the current investigation was to define the extent to which p16{sup INK4a} dysfunction contributes to the development of rodent lung tumors and to determine the mechanism of inactivation of the gene. There is no evidence to suggest a loss of function of the p16{sup INK4a} tumor suppressor gene in these primary murine lung tumors by mutation, deletion, or methylation.

  20. PML tumor suppressor protein is required for HCV production

    Energy Technology Data Exchange (ETDEWEB)

    Kuroki, Misao [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan); Research Fellow of the Japan Society for the Promotion of Science (Japan); Center for AIDS Research, Kumamoto University, Kumamoto 860-0811 (Japan); Ariumi, Yasuo, E-mail: ariumi@kumamoto-u.ac.jp [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan); Center for AIDS Research, Kumamoto University, Kumamoto 860-0811 (Japan); Hijikata, Makoto [Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto 606-8507 (Japan); Ikeda, Masanori; Dansako, Hiromichi [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan); Wakita, Takaji [Department of Virology II, National Institute of Infectious Diseases, Tokyo 162-8640 (Japan); Shimotohno, Kunitada [Research Center for Hepatitis and Immunology, National Center for Global Health and Medicine, Ichikawa, Chiba 272-8516 (Japan); Kato, Nobuyuki [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan)

    2013-01-11

    Highlights: Black-Right-Pointing-Pointer PML tumor suppressor protein is required for HCV production. Black-Right-Pointing-Pointer PML is dispensable for HCV RNA replication. Black-Right-Pointing-Pointer HCV could not alter formation of PML-NBs. Black-Right-Pointing-Pointer INI1 and DDX5, PML-related proteins, are involved in HCV life cycle. -- Abstract: PML tumor suppressor protein, which forms discrete nuclear structures termed PML-nuclear bodies, has been associated with several cellular functions, including cell proliferation, apoptosis and antiviral defense. Recently, it was reported that the HCV core protein colocalizes with PML in PML-NBs and abrogates the PML function through interaction with PML. However, role(s) of PML in HCV life cycle is unknown. To test whether or not PML affects HCV life cycle, we examined the level of secreted HCV core and the infectivity of HCV in the culture supernatants as well as the level of HCV RNA in HuH-7-derived RSc cells, in which HCV-JFH1 can infect and efficiently replicate, stably expressing short hairpin RNA targeted to PML. In this context, the level of secreted HCV core and the infectivity in the supernatants from PML knockdown cells was remarkably reduced, whereas the level of HCV RNA in the PML knockdown cells was not significantly affected in spite of very effective knockdown of PML. In fact, we showed that PML is unrelated to HCV RNA replication using the subgenomic HCV-JFH1 replicon RNA, JRN/3-5B. Furthermore, the infectivity of HCV-like particle in the culture supernatants was significantly reduced in PML knockdown JRN/3-5B cells expressing core to NS2 coding region of HCV-JFH1 genome using the trans-packaging system. Finally, we also demonstrated that INI1 and DDX5, the PML-related proteins, are involved in HCV production. Taken together, these findings suggest that PML is required for HCV production.

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

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    Apoptosis; cancer; cell cycle; MDM2 overexpression; tumour suppressor .... model of the p53-MDM2 negative feedback loop included an .... MDM2 overexpression, when subjected to nutlin-3 treatment. Some aspects of the model are similar to those ... A family of proteases termed caspases .... Implications for therapy; Proc.

  2. Loss of p53 enhances the function of the endoplasmic reticulum through activation of the IRE1α/XBP1 pathway

    Science.gov (United States)

    Kodama, Rika; Byun, Sanguine; Yoon, Kyoung Wan; Hiraki, Masatsugu; Mandinova, Anna; Lee, Sam W.

    2015-01-01

    Altered regulation of ER stress response has been implicated in a variety of human diseases, such as cancer and metabolic diseases. Excessive ER function contributes to malignant phenotypes, such as chemoresistance and metastasis. Here we report that the tumor suppressor p53 regulates ER function in response to stress. We found that loss of p53 function activates the IRE1α/XBP1 pathway to enhance protein folding and secretion through upregulation of IRE1α and subsequent activation of its target XBP1. We also show that wild-type p53 interacts with synoviolin (SYVN1)/HRD1/DER3, a transmembrane E3 ubiquitin ligase localized to ER during ER stress and removes unfolded proteins by reversing transport to the cytosol from the ER, and its interaction stimulates IRE1α degradation. Moreover, IRE1α inhibitor suppressed protein secretion, induced cell death in p53-deficient cells, and strongly suppressed the formation of tumors by p53-deficient human tumor cells in vivo compared with those that expressed wild-type p53. Therefore, our data imply that the IRE1α/XBP1 pathway serves as a target for therapy of chemoresistant tumors that express mutant p53. PMID:26254280

  3. Fenofibrate inhibited pancreatic cancer cells proliferation via activation of p53 mediated by upregulation of LncRNA MEG3

    International Nuclear Information System (INIS)

    Hu, Duanmin; Su, Cunjin; Jiang, Min; Shen, Yating; Shi, Aiming; Zhao, Fenglun; Chen, Ruidong; Shen, Zhu; Bao, Junjie; Tang, Wen

    2016-01-01

    There is still no suitable drug for pancreatic cancer treatment, which is one of the most aggressive human tumors. Maternally expressed gene 3 (MEG3), a LncRNA, has been suggested as a tumor suppressor in a range of human tumors. Studies found fenofibrate exerted anti-tumor roles in various human cancer cell lines. However, its role in pancreatic cancer remains unknown. The present study aimed to explore the impacts of fenofibrate on pancreatic cancer cell lines, and to investigate MEG3 role in its anti-tumor mechanisms. We used MTT assay to determine cells proliferation, genome-wide LncRNA microarray analysis to identify differently expressed LncRNAs, siRNA or pCDNA-MEG3 transfection to interfere or upregulate MEG3 expression, western blot to detect protein levels, real-time PCR to determine MEG3 level. Fenofibrate significantly inhibited proliferation of pancreatic cancer cells, increased MEG3 expression and p53 levels. Moreover, knockdown of MEG3 attenuated cytotoxicity induced by fenofibrate. Furthermore, overexpression of MEG3 induced cells death and increased p53 expression. Our results indicated fenofibrate inhibited pancreatic cancer cells proliferation via activation of p53 mediated by upregulation of MEG3. - Highlights: • We found that fenofibrate suppressed proliferation of pancreatic cancer cells. • We found fenofibrate increased LncRNA-MEG3 expression and p53 level in PANC-1 cells. • Inhibition of MEG3 expression attenuated anti-tumor effects of fenofibrate.

  4. Fenofibrate inhibited pancreatic cancer cells proliferation via activation of p53 mediated by upregulation of LncRNA MEG3

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Duanmin [Department of Gastroenterology, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Su, Cunjin [Department of Pharmacy, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Jiang, Min [Department of Breast Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215004 (China); Shen, Yating [Department of Gastroenterology, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Shi, Aiming; Zhao, Fenglun [Department of Pharmacy, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Chen, Ruidong [Department of Gastroenterology, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Shen, Zhu [Department of Pharmacy, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Bao, Junjie, E-mail: baojjsdfey@sina.com [Department of Pharmacy, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Tang, Wen, E-mail: sztangwen@163.com [Department of Gastroenterology, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China)

    2016-03-04

    There is still no suitable drug for pancreatic cancer treatment, which is one of the most aggressive human tumors. Maternally expressed gene 3 (MEG3), a LncRNA, has been suggested as a tumor suppressor in a range of human tumors. Studies found fenofibrate exerted anti-tumor roles in various human cancer cell lines. However, its role in pancreatic cancer remains unknown. The present study aimed to explore the impacts of fenofibrate on pancreatic cancer cell lines, and to investigate MEG3 role in its anti-tumor mechanisms. We used MTT assay to determine cells proliferation, genome-wide LncRNA microarray analysis to identify differently expressed LncRNAs, siRNA or pCDNA-MEG3 transfection to interfere or upregulate MEG3 expression, western blot to detect protein levels, real-time PCR to determine MEG3 level. Fenofibrate significantly inhibited proliferation of pancreatic cancer cells, increased MEG3 expression and p53 levels. Moreover, knockdown of MEG3 attenuated cytotoxicity induced by fenofibrate. Furthermore, overexpression of MEG3 induced cells death and increased p53 expression. Our results indicated fenofibrate inhibited pancreatic cancer cells proliferation via activation of p53 mediated by upregulation of MEG3. - Highlights: • We found that fenofibrate suppressed proliferation of pancreatic cancer cells. • We found fenofibrate increased LncRNA-MEG3 expression and p53 level in PANC-1 cells. • Inhibition of MEG3 expression attenuated anti-tumor effects of fenofibrate.

  5. Maintaining appearances-The role of p53 in adult neurogenesis

    International Nuclear Information System (INIS)

    Medrano, Silvia; Scrable, Heidi

    2005-01-01

    In the adult mammalian brain, neuronal turnover continues to replenish cells in existing neuronal circuits, such as those involved either in odor discrimination or in learning and memory, throughout life. With age, however, the capacity for neurogenesis diminishes and these functions become impaired. Neuronal turnover is a two-step process, which first generates excess neuronal progenitors and then eliminates all but the few that differentiate into fully functional neurons. This process requires a fine balance between cell proliferation and cell death. Altered activity of the tumor suppressor p53 can upset this balance by affecting the rate of cell proliferation, but not the rate of cell death, in neurogenic regions of the adult brain. Genetically engineered mice in which p53 activity is increased demonstrate that premature loss of neurogenic capacity is linked to accelerated organismal aging

  6. Tumor Suppressor Activity of the EphB2 Receptor in Prostate Cancer

    National Research Council Canada - National Science Library

    Pasquale, Elena B

    2007-01-01

    Mutations have been recently identified in the EphB2 receptor gene in prostate cancer suggesting that EphB2, a member of the large Eph receptor tyrosine kinase family, is a tumor suppressor in prostate cancer...

  7. Tumor Suppressor Activity of the EphB2 Receptor in Prostate Cancer

    National Research Council Canada - National Science Library

    Pasquale, Elena B

    2006-01-01

    Mutations have been recently identified in the EphB2 receptor gene in prostate cancer suggesting that EphB2, a member of the large Eph receptor tyrosine kinase family, is a tumor suppressor in prostate cancer...

  8. p53 Gene (NY-CO-13 Levels in Patients with Chronic Myeloid Leukemia: The Role of Imatinib and Nilotinib

    Directory of Open Access Journals (Sweden)

    Hayder M. Al-kuraishy

    2018-01-01

    Full Text Available The p53 gene is also known as tumor suppressor p53. The main functions of the p53 gene are an anticancer effect and cellular genomic stability via various pathways including activation of DNA repair, induction of apoptosis, and arresting of cell growth at the G1/S phase. Normally, the p53 gene is inactivated by mouse double minute 2 proteins (mdm2, but it is activated in chronic myeloid leukemia (CML. Tyrosine kinase inhibitors are effective chemotherapeutic agents in the management of CML. The purpose of the present study was to evaluate the differential effect of imatinib and nilotinib on p53 gene serum levels in patients with CML. A total number of 60 patients with chronic myeloid leukemia with ages ranging from 47 to 59 years were recruited from the Iraqi Hematology Center. They started with tyrosine kinase inhibitors as first-line chemotherapy. They were divided into two groups—Group A, 29 patients treated with imatinib and Group B, 31 patients treated with nilotinib—and compared with 28 healthy subjects for evaluation p53 serum levels regarding the selective effect of either imatinib or nilotinib. There were significantly (p < 0.01 high p53 gene serum levels in patients with CML (2.135 ± 1.44 ng/mL compared to the control (0.142 ± 0.11 ng/mL. Patients with CML that were treated with either imatinib or nilotinib showed insignificant differences in most of the hematological profile (p > 0.05 whereas, p53 serum levels were high (3.22 ± 1.99 ng/mL in nilotinib-treated patients and relatively low (1.18 ± 0.19 ng/mL in imatinib-treated patients (p = 0.0001. Conclusions: Nilotinib is more effective than imatinib in raising p53 serum levels in patients with chronic myeloid leukemia.

  9. Chorionic gonadotropin regulates the transcript level of VHL, p53, and HIF-2alpha in human granulosa lutein cells.

    Science.gov (United States)

    Herr, D; Keck, C; Tempfer, C; Pietrowski, Detlef

    2004-12-01

    The ovarian corpus luteum plays a critical role in reproduction being the primary source of circulating progesterone. After ovulation the corpus luteum is build by avascular granulosa lutein cells through rapid vascularization regulated by gonadotropic hormones. The present study was performed to investigate whether this process might be influenced by the human chorionic gonadotropin (hCG)-dependent expression of different tumor suppressor genes and hypoxia dependent transcription factors. RNA was isolated from cultured granulosa lutein cells, transcribed into cDNA, and the transcript level of following genes were determined: RB-1, VHL, NF-1, NF-2, Wt-1, p53, APC, and hypoxia inducible factor-1 (HIF-1), -2, and -3alpha. Additionally, the influence of hCG on the expression of VHL, p53, and HIf2alpha were investigated. We demonstrate that in human granulosa lutein cells the tumor suppressor genes RB-1, VHL, NF-1, NF-2, Wt-1, p53, and APC and the hypoxia dependent transcription factors HIF-1alpha, -2alpha, and -3alpha are expressed. In addition, we showed that hCG regulates the expression of p53, VHL, and HIF-2alpha. Our results indicate that hCG may determine the growth and development of the corpus luteum by mediating hypoxic and apoptotic pathways in human granulosa lutein cells. Copyright 2004 Wiley-Liss, Inc.

  10. ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-15-1-0277 TITLE: ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer PRINCIPAL INVESTIGATOR: Dr...Rohit Bose CONTRACTING ORGANIZATION: Sloan Kettering Institute for Cancer Research New York NY 10065 REPORT DATE: October 2017 TYPE OF REPORT...4. TITLE AND SUBTITLE ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-15-1-0277 5c

  11. ERF is a Potential ERK Modulated Tumor Suppressor in Prostate Cancer

    Science.gov (United States)

    2016-10-01

    6/27/2016 - 6/27/2019 1.20 calendar Prostate Cancer Foundation (formerly CaP CURE) $ 75,000 Epigenetic ...AWARD NUMBER: W81XWH-15-1-0277 TITLE: ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer PRINCIPAL INVESTIGATOR: Dr. Rohit...4. TITLE AND SUBTITLE ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-15-1-0277

  12. Expression of p53 and p21 in primary glioblastomas

    International Nuclear Information System (INIS)

    Gross, M.W.; Nashwan, K.; Engenhart-Cabillic, R.; Kraus, A.; Mennel, H.D.; Schlegel, J.

    2005-01-01

    Background and purpose: primary glioblastomas (GBMs) are highly radioresistant, and in contrast to secondary GBMs, they bear wild-type (wt) p53 protein, which is stabilized in a proportion of these tumors. Therefore, it was investigated in vivo whether p53 expression has prognostic value in patients undergoing radiochemotherapy. Additionally, the authors tried to identify, in vitro, subgroups of primary GBM with different susceptibilities to irradiation, on the basis of their p53 and p21 responses to ionizing radiation. Material and methods: tumor tissue samples from 31 patients suffering from primary GBM undergoing a combined radiochemotherapy with topotecan were investigated. The percentage of cells expressing p53 protein was determined immunohistochemically. Additionally, primary cultures from eleven primary GBMs were established and investigated. p53 and p21 expressions were evaluated before irradiation with 10 Gy and at 2 and 8 h after irradiation. p53 protein expression was measured by western analysis and p21 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). Results: the percentage of p53-positive cells within the tumor specimens obtained from the 31 patients ranged from 0% to 28%, the median value being 4.3%. No significant correlation with disease-free survival or overall survival was found. In vitro, p53 protein was detected in seven of eleven cultures from primary GBM. After irradiation a decrease in p53 protein expression was seen in six of the seven p53-positive cultures. Half of the cultures (two of four) without basal p53 expression showed an increase in p53 expression after irradiation. Basal overexpression of p21 was detected in six of the eleven cultures; in four out of six irradiation led to a decrease in p21 expression. In all cell lines (five of eleven) initially showing absent p21 expression, irradiation induced p21 expression. Despite these responses, G1 arrest was not detectable in any of the GBM cultures

  13. Pharmacological stimulation of p53 with low-dose doxorubicin ameliorates diet-induced nonalcoholic steatosis and steatohepatitis

    Directory of Open Access Journals (Sweden)

    Begoña Porteiro

    2018-02-01

    Full Text Available Objective: Recent reports have implicated the p53 tumor suppressor in the regulation of lipid metabolism. We hypothesized that the pharmacological activation of p53 with low-dose doxorubicin, which is widely used to treat several types of cancer, may have beneficial effects on nonalcoholic fatty liver disease (NAFLD and nonalcoholic steatohepatitis (NASH. Methods: We used long-term pharmacological activation of p53 by i.p. or oral administration of low-dose doxorubicin in different animal models of NAFLD (high fat diet containing 45% and 60% kcal fat and NASH (methionine- and choline-deficient diet and choline deficiency combined with high fat diet. We also administered doxorubicin in mice lacking p53 in the liver and in two human hepatic cells lines (HepG2 and THLE2. Results: The attenuation of liver damage was accompanied by the stimulation of fatty acid oxidation and decrease of lipogenesis, inflammation, and ER stress. The effects of doxorubicin were abrogated in mice with liver-specific ablation of p53. Finally, the effects of doxorubicin on lipid metabolism found in animal models were also present in two human hepatic cells lines, in which the drug stimulated fatty acid oxidation and inhibited de novo lipogenesis at doses that did not cause changes in apoptosis or cell viability. Conclusion: These data provide new evidence for targeting p53 as a strategy to treat liver disease. Keywords: Obesity, Lipid metabolism, Inflammation

  14. Repression of estrogen receptor β function by putative tumor suppressor DBC1

    International Nuclear Information System (INIS)

    Koyama, Satoshi; Wada-Hiraike, Osamu; Nakagawa, Shunsuke; Tanikawa, Michihiro; Hiraike, Haruko; Miyamoto, Yuichiro; Sone, Kenbun; Oda, Katsutoshi; Fukuhara, Hiroshi; Nakagawa, Keiichi; Kato, Shigeaki; Yano, Tetsu; Taketani, Yuji

    2010-01-01

    It has been well established that estrogen is involved in the pathophysiology of breast cancer. Estrogen receptor (ER) α appears to promote the proliferation of cancer tissues, while ERβ can protect against the mitogenic effect of estrogen in breast tissue. The expression status of ERα and ERβ may greatly influence on the development, treatment, and prognosis of breast cancer. Previous studies have indicated that the deleted in breast cancer 1 (DBC1/KIAA1967) gene product has roles in regulating functions of nuclear receptors. The gene encoding DBC1 is a candidate for tumor suppressor identified by genetic search for breast cancer. Caspase-dependent processing of DBC1 promotes apoptosis, and depletion of the endogenous DBC1 negatively regulates p53-dependent apoptosis through its specific inhibition of SIRT1. In addition, DBC1 modulates ERα expression and promotes breast cancer cell survival by binding to ERα. Here we report an ERβ-specific repressive function of DBC1. Immunoprecipitation and immunofluorescence studies show that ERβ and DBC1 interact in a ligand-independent manner similar to ERα. In vitro pull-down assays revealed a direct interaction between DBC1 amino-terminus and activation function-1/2 domain of ERβ. Although DBC1 shows no influence on the ligand-dependent transcriptional activation function of ERα, the expression of DBC1 negatively regulates the ligand-dependent transcriptional activation function of ERβin vivo, and RNA interference-mediated depletion of DBC1 stimulates the transactivation function of ERβ. These results implicate the principal role of DBC1 in regulating ERβ-dependent gene expressions.

  15. Enhancement of radiosensitivity of recombinant Ad-p53 gene on human lung adenocarcinoma cell with different p53 status

    International Nuclear Information System (INIS)

    Pang Dequan; Wang Peiguo; Wang Ping; Zhang Weiming

    2008-01-01

    Objective: To investigate the enhancement of radiosensitivity of recombinant Ad-p53 gene on human lung adenocarcinoma cell lines(A549 and GLC-82) with different p53 status in vitro. Methods: Two human lung adenocarcinoma cell lines of A549 and GLC-82 were examined on their difference in p53 status with immunohistochemistry stain and PCR-SSCP technique. Expand Ad-wtp53 was transfected into tumor cells. Clonogenic assays were performed to evaluate the inhibition effect on cell growth and the degree of sensitization to irradiation. Apoptosis and cell cycle changes were determined using the flow cytometry assay. Results: The A549 cell line presented positive P53 expression while GLC-82 negative. GLC-82 bore mutant p53 on the exon 7. The wtp53 gene could be efficiently expressed in the two cell lines and greatly inhibit the cell growth. Its efficiency didn't depend on the intrinsic p53 genetic status. After irradiation, its function of inducing G 1 arrest and apoptosis on GLC-82 cell line was much stronger than the A549 cell line. In both the A549 and GLC-82 cell lines, the combination of Ad-p53 plus radiation resulted in more apoptosis than the others. There was no significant difference between two groups. Conclusions: Ad-p53 can depress the tumor growth and enhance the radiosensitivity of human lung adenocarcinoma cells. And this effect is independent of endogenous p53 status. (authors)

  16. Chromatin-Bound MDM2 Regulates Serine Metabolism and Redox Homeostasis Independently of p53.

    Science.gov (United States)

    Riscal, Romain; Schrepfer, Emilie; Arena, Giuseppe; Cissé, Madi Y; Bellvert, Floriant; Heuillet, Maud; Rambow, Florian; Bonneil, Eric; Sabourdy, Frédérique; Vincent, Charles; Ait-Arsa, Imade; Levade, Thierry; Thibaut, Pierre; Marine, Jean-Christophe; Portais, Jean-Charles; Sarry, Jean-Emmanuel; Le Cam, Laurent; Linares, Laetitia K

    2016-06-16

    The mouse double minute 2 (MDM2) oncoprotein is recognized as a major negative regulator of the p53 tumor suppressor, but growing evidence indicates that its oncogenic activities extend beyond p53. Here, we show that MDM2 is recruited to chromatin independently of p53 to regulate a transcriptional program implicated in amino acid metabolism and redox homeostasis. Identification of MDM2 target genes at the whole-genome level highlights an important role for ATF3/4 transcription factors in tethering MDM2 to chromatin. MDM2 recruitment to chromatin is a tightly regulated process that occurs during oxidative stress and serine/glycine deprivation and is modulated by the pyruvate kinase M2 (PKM2) metabolic enzyme. Depletion of endogenous MDM2 in p53-deficient cells impairs serine/glycine metabolism, the NAD(+)/NADH ratio, and glutathione (GSH) recycling, impacting their redox state and tumorigenic potential. Collectively, our data illustrate a previously unsuspected function of chromatin-bound MDM2 in cancer cell metabolism. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Role of DNA mismatch repair and p53 in signaling induction of apoptosis by alkylating agents.

    Science.gov (United States)

    Hickman, M J; Samson, L D

    1999-09-14

    All cells are unavoidably exposed to chemicals that can alkylate DNA to form genotoxic damage. Among the various DNA lesions formed, O(6)-alkylguanine lesions can be highly cytotoxic, and we recently demonstrated that O(6)-methylguanine (O(6)MeG) and O(6)-chloroethylguanine (O(6)CEG) specifically initiate apoptosis in hamster cells. Here we show, in both hamster and human cells, that the MutSalpha branch of the DNA mismatch repair pathway (but not the MutSbeta branch) is absolutely required for signaling the initiation of apoptosis in response to O(6)MeGs and is partially required for signaling apoptosis in response to O(6)CEGs. Further, O(6)MeG lesions signal the stabilization of the p53 tumor suppressor, and such signaling is also MutSalpha-dependent. Despite this, MutSalpha-dependent apoptosis can be executed in a p53-independent manner. DNA mismatch repair status did not influence the response of cells to other inducers of p53 and apoptosis. Thus, it appears that mismatch repair status, rather than p53 status, is a strong indicator of the susceptibility of cells to alkylation-induced apoptosis. This experimental system will allow dissection of the signal transduction events that couple a specific type of DNA base lesion with the final outcome of apoptotic cell death.

  18. Tumor-suppressor activity of RRIG1 in breast cancer

    International Nuclear Information System (INIS)

    Zhang, Guihong; Brewster, Abenaa; Guan, Baoxiang; Fan, Zhen; Brown, Powel H; Xu, Xiao-Chun

    2011-01-01

    Retinoid receptor-induced gene-1 (RRIG1) is a novel gene that has been lost in several types of human cancers. The aim of this study was to determine whether RRIG1 plays a role in breast cancer, such as in the suppression of breast cancer cell growth and invasion. Immunohistochemistry was used to detect RRIG1 expression in breast tissue specimens. Gene transfection was used to restore or knock down RRIG1 expression in breast cancer cell lines for analysis of cell viability, colony formation, and migration/invasion potential. Reverse-transcription polymerase chain reaction and western blot assays were used to detect the changes in gene expression. The RhoA activation assay was used to assess RRIG1-induced inhibition of RhoA activity. The immunohistochemical data showed that RRIG1 expression was reduced in breast cancer tissues compared with normal and atypical hyperplastic breast tissues. RRIG1 expression was inversely correlated with lymph node metastasis of breast cancer but was not associated with the status of hormone receptors, such as estrogen receptor, progesterone receptor, or HER2. Furthermore, restoration of RRIG1 expression inhibited proliferation, colony formation, migration, and invasion of breast cancer cells. Expression of RRIG1 also reduced phosphorylated Erk1/2 and Akt levels; c-Jun, MMP9, and Akt expressions; and RhoA activity. In contrast, knockdown of RRIG1 expression promoted breast cancer cell proliferation, colony formation, migration, and invasion potential. The data from the current study indicated that RRIG1 expression was reduced or lost in breast cancer and that restoration of RRIG1 expression suppressed breast cancer cell growth and invasion capacity. Future studies will determine the underlying molecular mechanisms and define RRIG1 as a tumor-suppressor gene in breast cancer

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

    Directory of Open Access Journals (Sweden)

    Youfeng Shen

    2017-11-01

    Full Text Available Abstract Background Pigs have many features that make them attractive as biomedical models for various diseases, including cancer. P53 is an important tumor suppressor gene that exerts a central role in protecting cells from oncogenic transformation and is mutated in a large number of human cancers. P53 mutations occur in almost every type of tumor and in over 50% of all tumors. In a recent publication, pigs with a mutated P53 gene were generated that resulted in lymphoma and renal and osteogenic tumors. However, approximately 80% of human tumors have dysfunctional P53. A P53-deficient pig model is still required to elucidate. Methods Transcription activator-like effector nucleases (TALENs were designed to target porcine P53 exon 4. The targeting activity was evaluated using a luciferase SSA recombination assay. P53 biallelic knockout (KO cell lines were established from single-cell colonies of fetal fibroblasts derived from Diannan miniature pigs followed by electroporation with TALENs plasmids. One cell line was selected as the donor cell line for somatic cell nuclear transfer (SCNT for the generation of P53 KO pigs. P53 KO stillborn fetuses and living piglets were obtained. Gene typing of the collected cloned individuals was performed by T7EI assay and sequencing. Fibroblast cells from Diannan miniature piglets with a P53 biallelic knockout or wild type were analyzed for the P53 response to doxorubicin treatment by confocal microscopy and western blotting. Results The luciferase SSA recombination assay revealed that the targeting activities of the designed TALENs were 55.35-fold higher than those of the control. Eight cell lines (8/19 were mutated for P53, and five of them were biallelic knockouts. One of the biallelic knockout cell lines was selected as nuclear donor cells for SCNT. The cloned embryos were transferred into five recipient gilts, three of them becoming pregnant. Five live fetuses were obtained from one surrogate by caesarean

  20. Studies of the Association of Arg72Pro of Tumor Suppressor Protein p53 with Type 2 Diabetes in a Combined Analysis of 55,521 Europeans

    DEFF Research Database (Denmark)

    Burgdorf, Kristoffer Sølvsten; Grarup, Niels; Justesen, Johanne Marie

    2011-01-01

    2 diabetes in the Danish samples. However, for all nine variants the estimate of increase in type 2 diabetes risk was observed for the same allele as previously reported. In a meta-analysis of published and online data including 55,521 Europeans the G-allele of rs1042522 in TP53 showed significant...... replicated associations in meta-analyses. Furthermore, we evaluated the impact on diabetes-related intermediate traits in a population-based sample of middle-aged Danes. Methods: We genotyped nine lead variants in the seven genes in 4,973 glucose-tolerant and 3,612 type 2 diabetes Danish individuals. In meta...... association with type 2 diabetes (OR = 1.06 95% CI 1.02–1.11, p = 0.0032). No substantial associations with diabetes-related intermediary phenotypes were found. Conclusion: The G-allele of TP53 rs1042522 is associated with an increased prevalence of type 2 diabetes in a combined analysis of 55,521 Europeans....

  1. Electrochemical detection of DNA binding by tumor suppressor p53 protein using osmium-labeled oligonucleotide probes and catalytic hydrogen evolution at the mercury electrode

    Czech Academy of Sciences Publication Activity Database

    Němcová, Kateřina; Šebest, Peter; Havran, Luděk; Orság, Petr; Fojta, Miroslav; Pivoňková, Hana

    2014-01-01

    Roč. 406, č. 24 (2014), s. 5843-5852 ISSN 1618-2642 R&D Projects: GA ČR(CZ) GAP301/11/2076; GA AV ČR(CZ) IAA400040901 Institutional support: RVO:68081707 Keywords : Electrochemical analysis * Labeled probes * Osmium complex Subject RIV: BO - Biophysics Impact factor: 3.436, year: 2014

  2. p53 Tumor Suppressor Protein Stability and Transcriptional Activity Are Targeted by Kaposi's Sarcoma-Associated Herpesvirus-Encoded Viral Interferon Regulatory Factor 3

    Czech Academy of Sciences Publication Activity Database

    Barešová, P.; Musilová, J.; Pitha, P. M.; Lubyová, Barbora

    2014-01-01

    Roč. 34, č. 3 (2014), s. 386-399 ISSN 0270-7306 Grant - others:GA ČR(CZ) GA204/09/0773 Institutional support: RVO:61388963 Keywords : ATM -dependent phosphorylation * primary effusion lymphoma * DNA-damage Subject RIV: CE - Biochemistry Impact factor: 4.777, year: 2014

  3. Preferential binding of p53 tumor suppressor to p21 promoter sites that contain inverted repeats capable of forming cruciform structure

    Czech Academy of Sciences Publication Activity Database

    Coufal, Jan; Jagelská, Eva; Liao, J.C.C.; Brázda, Václav

    2013-01-01

    Roč. 441, č. 1 (2013), s. 83-85 ISSN 0006-291X R&D Projects: GA ČR(CZ) GAP301/11/2076; GA ČR(CZ) GBP206/12/G151 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : DNA-BINDING * SUPERCOILED DNA * EXPRESSION Subject RIV: BO - Biophysics Impact factor: 2.281, year: 2013

  4. p53 and PTEN/MMAC1/TEP1 gene therapy of human prostate PC-3 carcinoma xenograft, using transferrin-facilitated lipofection gene delivery strategy.

    Science.gov (United States)

    Seki, Masafumi; Iwakawa, Jun; Cheng, Helen; Cheng, Pi-Wan

    2002-04-10

    We previously reported that supplementation of a cationic liposome with transferrin (Tf) greatly enhanced lipofection efficiency (P.-W. Cheng, Hum. Gene Ther. 1996;7:275-282). In this study, we examined the efficacy of p53 and PTEN tumor suppressor gene therapy in a mouse xenograft model of human prostate PC-3 carcinoma cells, using a vector consisting of dimyristoyloxypropyl-3-dimethylhydroxyethyl ammonium bromide (DMRIE)-cholesterol (DC) and Tf. When the volume of the tumors grown subcutaneously in athymic nude mice reached 50-60 mm(3), three intratumoral injections of the following four formulations were performed during week 1 and then during week 3: (1) saline, (2) DC + Tf + pCMVlacZ, (3) DC + Tf + pCMVPTEN, and (4) DC + Tf + pCMVp53 (standard formulation). There was no significant difference in tumor volume and survival between group 1 and group 2 animals. As compared with group 1 controls, group 3 animals had slower tumor growth during the first 3 weeks but thereafter their tumor growth rate was similar to that of the controls. By day 2 posttreatment, group 4 animals had significantly lower tumor volume relative to initial tumor volume as well as controls at the comparable time point. Also, animals treated with p53 survived longer. Treatment with DC, Tf, pCMVp53, DC + pCMVp53, or Tf + pCMVp53 had no effect on tumor volume or survival. Expression of p53 protein and apoptosis were detected in tumors treated with the standard formulation, thus associating p53 protein expression and apoptosis with efficacy. However, p53 protein was expressed in only a fraction of the tumor cells, suggesting a role for bystander effects in the efficacy of p53 gene therapy. We conclude that intratumoral gene delivery by a nonviral vector consisting of a cationic liposome and Tf can achieve efficacious p53 gene therapy of prostate cancer.

  5. Low grade inflammation inhibits VEGF induced HUVECs migration in p53 dependent manner

    International Nuclear Information System (INIS)

    Panta, Sushil; Yamakuchi, Munekazu; Shimizu, Toshiaki; Takenouchi, Kazunori; Oyama, Yoko; Koriyama, Toyoyasu; Kojo, Tsuyoshi; Hashiguchi, Teruto

    2017-01-01

    In the course of studying crosstalk between inflammation and angiogenesis, high doses of pro-inflammatory factors have been reported to induce apoptosis in cells. Under normal circumstances also the pro-inflammatory cytokines are being released in low doses and are actively involved in cell signaling pathways. We studied the effects of low grade inflammation in growth factor induced angiogenesis using tumor necrosis factor alfa (TNFα) and vascular endothelial growth factor A (VEGF) respectively. We found that low dose of TNFα can inhibit VEGF induced angiogenesis in human umbilical vein endothelial cells (HUVECs). Low dose of TNFα induces mild upregulation and moreover nuclear localization of tumor suppressor protein 53 (P53) which causes decrease in inhibitor of DNA binding-1 (Id1) expression and shuttling to the cytoplasm. In absence of Id1, HUVECs fail to upregulate β 3 -integrin and cell migration is decreased. Connecting low dose of TNFα induced p53 to β 3 -integrin through Id1, we present additional link in cross talk between inflammation and angiogenesis. - Highlights: • Low grade inflammation (low dose of TNF alfa) inhibits VEGF induced endothelial cells migration. • The low grade inflammation with VEGF treatment upregulates P53 to a nonlethal level. • P53 activation inhibits Id1 shuttling to the cytoplasm in endothelial cells. • Inhibition of Id1 resulted in downregulation of β 3 -integrin which cause decrease in cell migration. • Inflammation and angiogenesis might cross-talk by P53 – Id1 – β 3 -integrin pathway in endothelial cells.

  6. ATM and p53 combined analysis predicts survival in glioblastoma multiforme patients: A clinicopathologic study.

    Science.gov (United States)

    Romano, Francesco Jacopo; Guadagno, Elia; Solari, Domenico; Borrelli, Giorgio; Pignatiello, Sara; Cappabianca, Paolo; Del Basso De Caro, Marialaura

    2018-06-01

    Glioblastoma is one of the most malignant cancers, with a distinguishing dismal prognosis: surgery followed by chemo- and radiotherapy represents the current standard of care, and chemo- and radioresistance underlie disease recurrence and short overall survival of patients suffering from this malignancy. ATM is a kinase activated by autophosphorylation upon DNA doublestrand breaks arising from errors during replication, byproducts of metabolism, chemotherapy or ionizing radiations; TP53 is one of the most popular tumor suppressor, with a preeminent role in DNA damage response and repair. To study the effects of the immunohistochemical expression of p-ATM and p53 in glioblastoma patients, 21 cases were retrospectively examined. In normal brain tissue, p-ATM was expressed only in neurons; conversely, in tumors cells, the protein showed a variable cytoplasmic expression (score: +,++,+++), with being completely undetectable in three cases. Statistical analysis revealed that high p-ATM score (++/+++) strongly correlated to shorter survival (P = 0.022). No difference in overall survival was registered between p53 normally expressed (NE) and overexpressed (OE) glioblastoma patients (P = 0.669). Survival analysis performed on the results from combined assessment of the two proteins showed that patients with NE p53 /low pATM score had longer overall survival than the NE p53/ high pATM score counterpart. Cox-regression analysis confirmed this finding (HR = 0.025; CI 95% = 0.002-0.284; P = 0.003). Our study outlined the immunohistochemical expression of p-ATM/p53 in glioblastomas and provided data on their possible prognostic/predictive of response role. A "non-oncogene addiction" to ATM for NEp53 glioblastoma could be postulated, strengthening the rationale for development of ATM inhibiting drugs. © 2018 Wiley Periodicals, Inc.

  7. Bioluminescence Detection of Cells Having Stabilized p53 in Response to a Genotoxic Event

    Directory of Open Access Journals (Sweden)

    Alnawaz Rehemtulla

    2004-01-01

    Full Text Available Inactivation of p53 is one of the most frequent molecular events in neoplastic transformation. Approximately 60% of all human tumors have mutations in both p53 alleles. Wild-type p53 activity is regulated in large part by the proteosome-dependent degradation of p53, resulting in a short p53 half-life in unstressed and untransformed cells. Activation of p53 by a variety of stimuli, including DNA damage induced by genotoxic drugs or radiation, is accomplished by stabilization of wild-type p53. The stabilized and active p53 can result in either cell-cycle arrest or apoptosis. Surprisingly, the majority of tumor-associated, inactivating p53 mutations also result in p53 accumulation. Thus, constitutive elevation of p53 levels in cells is a reliable measure of p53 inactivation, whereas transiently increased p53 levels reflect a recent genotoxic stress. In order to facilitate noninvasive imaging of p53 accumulation, we here describe the construction of a p53-luciferase fusion protein. Induction of DNA damage in cells expressing the fusion protein resulted in a time-dependent accumulation of the fusion that was noninvasively detected using bioluminescence imaging and validated by Western blot analysis. The p53-Luc protein retains p53 function because its expression in HCT116 cells lacking functional p53 resulted in activation of p21 expression as well as induction of apoptosis in response to a DNA damaging event. Employed in a transgenic animal model, the proposed p53-reporter fusion protein will be useful for studying p53 activation in response to exposure to DNA-damaging carcinogenic agents. It could also be used to study p53 stabilization as a result of inactivating p53 mutations. Such studies will further our understanding of p53's role as the “guardian of the genome” and its function in tumorigenesis.

  8. RITA inhibits multiple myeloma cell growth through induction of p53-mediated caspase-dependent apoptosis and synergistically enhances nutlin-induced cytotoxic responses.

    Science.gov (United States)

    Saha, Manujendra N; Jiang, Hua; Mukai, Asuka; Chang, Hong

    2010-11-01

    Mutations or deletions of p53 are relatively rare in multiple myeloma (MM), at least in newly diagnosed patients. Thus, restoration of p53 tumor suppressor function in MM by blocking the inhibitory role of murine double minute 2 (MDM2) is a promising and applicable therapeutic strategy. RITA and nutlin are two new classes of small molecule MDM2 inhibitors that prevent the p53-MDM2 interaction. Earlier reports showed p53-dependent activity of RITA in solid tumors as well as in leukemias. We and others recently described nutlin-induced apoptosis in MM cells, but it remains unclear whether RITA exerts antimyeloma activity. Here, we found that RITA activates the p53 pathway and induces apoptosis in MM cell lines and primary MM samples, preferentially killing myeloma cells. The activation of p53 induced by RITA was mediated through modulation of multiple apoptotic regulatory proteins, including upregulation of a proapoptotic protein (NOXA), downregulation of an antiapoptotic protein, Mcl-1, and activation of caspases through extrinsic pathways. Moreover, a number of key p53-mediated apoptotic target genes were identified by gene expression profiling and further validated by quantitative real-time PCR. Importantly, the combination of RITA with nutlin displayed a strong synergism on growth inhibition with the combination index ranging from 0.56 to 0.82 in MM cells. Our data support further clinical evaluation of RITA as a potential novel therapeutic intervention in MM. ©2010 AACR.

  9. Loss of ribosomal protein L11 affects zebrafish embryonic development through a p53-dependent apoptotic response.

    Directory of Open Access Journals (Sweden)

    Anirban Chakraborty

    Full Text Available Ribosome is responsible for protein synthesis in all organisms and ribosomal proteins (RPs play important roles in the formation of a functional ribosome. L11 was recently shown to regulate p53 activity through a direct binding with MDM2 and abrogating the MDM2-induced p53 degradation in response to ribosomal stress. However, the studies were performed in cell lines and the significance of this tumor suppressor function of L11 has yet to be explored in animal models. To investigate the effects of the deletion of L11 and its physiological relevance to p53 activity, we knocked down the rpl11 gene in zebrafish and analyzed the p53 response. Contrary to the cell line-based results, our data indicate that an L11 deficiency in a model organism activates the p53 pathway. The L11-deficient embryos (morphants displayed developmental abnormalities primarily in the brain, leading to embryonic lethality within 6-7 days post fertilization. Extensive apoptosis was observed in the head region of the morphants, thus correlating the morphological defects with apparent cell death. A decrease in total abundance of genes involved in neural patterning of the brain was observed in the morphants, suggesting a reduction in neural progenitor cells. Upregulation of the genes involved in the p53 pathway were observed in the morphants. Simultaneous knockdown of the p53 gene rescued the developmental defects and apoptosis in the morphants. These results suggest that ribosomal dysfunction due to the loss of L11 activates a p53-dependent checkpoint response to prevent improper embryonic development.

  10. p53 levels, cell cycle kinetics and radiosensitivity in two SV40 transformed Wi38VA13 fibroblast strains

    International Nuclear Information System (INIS)

    Werner, F.; Zoelzer, F.; Streffer, C.

    2001-01-01

    Background: The tumor suppressor protein p53 which can mediate an ionizing radiation-induced G 1 arrest in mammalian cells, forms complexes with SV40 large T antigen (l-T-Ag). We have analyzed the p53 levels, the capability to undergo a G 1 arrest and the radiosensitivity of two SV40 transformed fibroblast strains differing in their large T antigen expression. Material and Methods: One of the two strains (VA13F) is the commercially available form of Wi38VA13, the other (VA13E) arose spontaneously from the original one in our laboratory. Their p53 levels were measured by means of flow cytometry (FCM) and Western blot (WB) with two p53 antibodies (Ab-3, clone PAb240; Ab-6, clone DO-1; both Oncogene Science). Cell cycle distributions were determined flow cytometrically after BrdU labeling at regular time intervals after exposure to 250 kV X-rays. Radiosensitivity was assessed in a clonogenicity assay. Results: The p53 levels of the two strains corresponded to their large T antigen expression, presumably due to complex formation between the two proteins. The strain with a high p53 level did not show a G 1 arrest and had a relatively high radiosensitivity, whereas the strain with a low p53 level showed a significant G 1 arrest and a lower radiosensitivity. Conclusion: These results suggest that 1. complex formation between the large T antigen and p53 reduces the latter's functionality; 2. in these two strains the G 1 arrest is one of the factors determining radiosensitivity. (orig.) [de

  11. Rapid colorimetric detection of p53 protein function using DNA-gold nanoconjugates with applications for drug discovery and cancer diagnostics.

    Science.gov (United States)

    Assah, Enock; Goh, Walter; Zheng, Xin Ting; Lim, Ting Xiang; Li, Jun; Lane, David; Ghadessy, Farid; Tan, Yen Nee

    2018-05-05

    The tumor suppressor protein p53 plays a central role in preventing cancer through interaction with DNA response elements (REs) to regulate target gene expression in cells. Due to its significance in cancer biology, relentless efforts have been directed toward understanding p53-DNA interactions for the development of cancer therapeutics and diagnostics. In this paper, we report a rapid, label-free and versatile colorimetric assay to detect wildtype p53 DNA-binding function in complex solutions. The assay design is based on a concept that alters interparticle-distances between RE-AuNPs from a crosslinking effect induced through tetramerization of wildtype p53 protein (p53-WT) upon binding to canonical DNA motifs modified on gold nanoparticles (RE-AuNPs). This leads to a visible solution color change from red to blue, which is quantifiable by the UV- visible absorption spectra with a detection limit of 5 nM. Contrastingly, no color change was observed for the binding-deficient p53 mutants and non-specific proteins due to their inability to crosslink RE-AuNPs. Based on this sensing principle, we further demonstrate its utility for fast detection of drug-induced DNA binding function to cancer-associated Y220C mutant p53 protein using well-established reactivating compounds. By exploiting the dominant-negative property of mutant p53 over p53-WT and interactions with RE-AuNPs, this assay is configurable to detect low numbers of mutant p53 expressing cells in miniscule sample fractions obtained from typical core needle biopsy-sized tissues without signal attrition, alluding to the potential for biopsy sampling in cancer diagnostics or for defining cancer margins. This nanogold enabled colorimetric assay provides a facile yet robust method for studying important parameters influencing p53-DNA interactions with great promises for clinically pertinent applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. [Tumor markers p53, sFAS, FASL, CEA and CA 19-9 in evaluating the effectiveness of surgical and pharmaco nutritional treatment of patients with gastric cancer].

    Science.gov (United States)

    Bluvshteĭn, G A; Lysenko, V G; Zakharova, N B; Kitaev, I V

    2012-01-01

    The objective of this study is to develop a marker panel of abnormalities of immune regulatory systems and cell genome in patients with gastric cancer for assessment of efficacy of surgical treatment in combination with pharmaco-nutritional therapy in early postoperative period. Expression of p53, sFAS, FASL, CEA, and CA 19-9, nutritial status, as well as incidence of purulent-septic complications in early postoperative period were determined in 40 patients with gastric cancer (21 patients--the test group and 19 patients--the comparative group) prior to a curative surgical intervention, postoperative days 1 and 7, while the pharmaco-nutritional therapy (the test group) or partial parenteral nutrition (the comparative group) has been performed. The pharmaco-nutritional therapy significantly decreases in activity of tumor suppressing genome, lymphocyte apoptosis, expression of oncology-associated markers, incidence of purulent-septic complications, as well as exacerbation risk for hypotrophy in patients with gastric cancer in early postoperative period. To assess the efficacy of the surgical intervention performed in patients with gastric cancer, an expression of mutant p53 and markers of lymphocyte apoptosis (sFAS/FASL) is reasonable to be evaluated together with determination of oncomarkers (CEA and CA 19-9).

  13. Simple mathematical method to quantify p53 mutations in occupational lung cancer

    International Nuclear Information System (INIS)

    Helal, N.L.

    2005-01-01

    Radon-222, a decay product of uranium-238 and a source of high linear energy transfer (LET) alpha -particles, has been implicated in the increase risk of lung cancer in uranium miners as well as non-miners. The p53 gene mutational spectrum reveals evidence for a direct causal effect of radon inhalation in lung cancer. This mutation has been proposed as a marker of radon exposure. The development of such markers may ultimately be of benefit in the reduction of occupational morbidity and mortality from occupational cancer. One of the tasks in risk assessment of genotoxic occupational radiation exposure is to devise a simple numerical method. This method may be used to quantify the relationship between radiation dose and the effect on the genetic sequences. The tumor suppressor gene (TSG) p53 is an ideal bio marker addressing questions of exposure and risk. These proteins may be suitable for the design of more effective or less invasive cancer therapies. The clinical outcome of lung cancer patients may correlate with the normal regulation of these patients and, therefore, their identification may be used as a guideline for future therapy modalities. To investigate the association between radon exposure and p53 mutations in lung tumors, we have implied a mathematical method. This method has been developed from a 2-D graphical representational technique that enables easy visualization of base distributions. This is of special relevance to libraries of single nucleotide polymorphic (SNP) genes

  14. Quantitative Methylation Profiles for Multiple Tumor Suppressor Gene Promoters in Salivary Gland Tumors

    Science.gov (United States)

    Durr, Megan L.; Mydlarz, Wojciech K.; Shao, Chunbo; Zahurak, Marianna L.; Chuang, Alice Y.; Hoque, Mohammad O.; Westra, William H.; Liegeois, Nanette J.; Califano, Joseph A.; Sidransky, David; Ha, Patrick K.

    2010-01-01

    Background Methylation profiling of tumor suppressor gene (TSGs) promoters is quickly becoming a powerful diagnostic tool for the early detection, prognosis, and even prediction of clinical response to treatment. Few studies address this in salivary gland tumors (SGTs); hence the promoter methylation profile of various TSGs was quantitatively assessed in primary SGT tissue to determine if tumor-specific alterations could be detected. Methodology DNA isolated from 78 tumor and 17 normal parotid gland specimens was assayed for promoter methylation status of 19 TSGs by fluorescence-based, quantitative methylation-specific PCR (qMSP). The data were utilized in a binary fashion as well as quantitatively (using a methylation quotient) allowing for better profiling and interpretation of results. Principal Findings The average number of methylation events across the studied genes was highest in salivary duct carcinoma (SDC), with a methylation value of 9.6, compared to the normal 4.5 (ptrend for increasing methylation in APC, Mint 1, PGP9.5, RAR-β, and Timp3. Conclusions/Significance Screening promoter methylation profiles in SGTs showed considerable heterogeneity. The methylation status of certain markers was surprisingly high in even normal salivary tissue, confirming the need for such controls. Several TSGs were found to be associated with malignant SGTs, especially SDC. Further study is needed to evaluate the potential use of these associations in the detection, prognosis, and therapeutic outcome of these rare tumors. PMID:20520817

  15. P53 autoantibodies in 1006 patients followed up for breast cancer

    International Nuclear Information System (INIS)

    Metcalfe, Su; Wheeler, Terence K; Picken, Sheila; Negus, Susanne; Jo Milner, A

    2000-01-01

    Serial plasma samples from 1006 patients with breast cancer revealed: (i) no correlation of p53 autoantibody status with disease status at the time of sample collection, or with menopausal status at time of primary diagnosis of breast cancer; (ii) 155 out of 1006 (15%) of patients were positive for p53 autoantibodies, and these patients tended to have a persistent autoantibody status throughout follow up, irrespective of disease behaviour; and (iii) where a negative autoantibody status was found at primary diagnosis of breast cancer, this negative status persisted throughout follow up, irrespective of later disease behaviour. We conclude that screening for p53 autoantibody status is not informative on residual tumour activity nor on therapeutic responsiveness. Dysfunction of the tumour-suppressor protein, p53, may be due to either mutational or epigenetic factors, each of which may lead to accumulation of cytoplasmic p53. Abnormal accumulation of p53 in breast cancer tissue is predictive of poor prognosis [1,2]. Humoral studies [3,4] have shown that cancer patients may develop immunity to abnormally expressed p53, as revealed by p53 autoantibodies in the blood. Again, prognostic correlates have been noted, with presence of circulating p53 autoantibodies at diagnosis of breast cancer being associated with reduced overall survival [5,6] and with poor prognostic factors such as high histological grade and the absence of hormone receptors [5,7,8]. Little is known of the potential value of p53 autoantibody in follow up of cancer. In lung cancer there is evidence that autoantibodies to p53 may provide a useful tool to monitor response to therapy [9,10], whereas serial measurements of autoantibodies to p53 in 40 patients with advanced ovarian cancer were not found to be clinically useful [11]. In breast cancer some 30% of node-negative patients will relapse within 5 years, but there is no current means to predict those who are at risk. We performed the present study to

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

    International Nuclear Information System (INIS)

    Handayaningsih, Anastasia-Evi; Takahashi, Michiko; Fukuoka, Hidenori; Iguchi, Genzo; Nishizawa, Hitoshi; Yamamoto, Masaaki; Suda, Kentaro; Takahashi, Yutaka

    2012-01-01

    Highlights: ► Cellular senescence plays an important role in tumorigenesis and aging process. ► We demonstrated IGF-I enhanced cellular senescence in primary confluent cells. ► IGF-I enhanced cellular senescence in the ROS and p53-dependent manner. ► 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 β-galactosidase (SA-β-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, γH2AX, the increased levels of p53 and p21 proteins, and activated SA-β-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-β-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.

  18. Human papilloma virus DNA and p53 mutation analysis on bladder washes in relation to clinical outcome of bladder cancer.

    NARCIS (Netherlands)

    Moonen, P.M.J.; Bakkers, J.M.J.E.; Kiemeney, L.A.L.M.; Schalken, J.A.; Melchers, W.J.G.; Witjes, J.A.

    2007-01-01

    OBJECTIVES: High-risk human papilloma virus (HPV) types stimulate degradation and deactivation of protein associated with the p53 tumour suppressor gene via the ubiquitin-dependent pathway. For a long time, changes of the p53 tumour suppressor gene have been correlated with poor clinical outcome in

  19. Human herpesvirus 6B inhibits cell proliferation by a p53-independent pathway

    DEFF Research Database (Denmark)

    Øster, Bodil; Kaspersen, M.D.; Kofod-Olsen, Emil

    2006-01-01

    BACKGROUND: Various forms of cellular stress can activate the tumour suppressor protein p53, an important regulator of cell cycle arrest, apoptosis, and cellular senescence. Cells infected by human herpesvirus 6B (HHV-6B) accumulate aberrant amounts of p53. OBJECTIVES: The aim of this study...

  20. The Satellite Cell Niche Regulates the Balance between Myoblast Differentiation and Self-Renewal via p53.

    Science.gov (United States)

    Flamini, Valentina; Ghadiali, Rachel S; Antczak, Philipp; Rothwell, Amy; Turnbull, Jeremy E; Pisconti, Addolorata

    2018-03-13

    Satellite cells are adult muscle stem cells residing in a specialized niche that regulates their homeostasis. How niche-generated signals integrate to regulate gene expression in satellite cell-derived myoblasts is poorly understood. We undertook an unbiased approach to study the effect of the satellite cell niche on satellite cell-derived myoblast transcriptional regulation and identified the tumor suppressor p53 as a key player in the regulation of myoblast quiescence. After activation and proliferation, a subpopulation of myoblasts cultured in the presence of the niche upregulates p53 and fails to differentiate. When satellite cell self-renewal is modeled ex vivo in a reserve cell assay, myoblasts treated with Nutlin-3, which increases p53 levels in the cell, fail to differentiate and instead become quiescent. Since both these Nutlin-3 effects are rescued by small interfering RNA-mediated p53 knockdown, we conclude that a tight control of p53 levels in myoblasts regulates the balance between differentiation and return to quiescence. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  1. The potential for tumor suppressor gene therapy in head and neck cancer.

    Science.gov (United States)

    Birkeland, Andrew C; Ludwig, Megan L; Spector, Matthew E; Brenner, J Chad

    2016-01-01

    Head and neck squamous cell carcinoma remains a highly morbid and fatal disease. Importantly, genomic sequencing of head and neck cancers has identified frequent mutations in tumor suppressor genes. While targeted therapeutics increasingly are being investigated in head and neck cancer, the majority of these agents are against overactive/overexpressed oncogenes. Therapy to restore lost tumor suppressor gene function remains a key and under-addressed niche in trials for head and neck cancer. Recent advances in gene editing have captured the interest of both the scientific community and the public. As our technology for gene editing and gene expression modulation improves, addressing lost tumor suppressor gene function in head and neck cancers is becoming a reality. This review will summarize new techniques, challenges to implementation, future directions, and ethical ramifications of gene therapy in head and neck cancer.

  2. GRIM-19 disrupts E6/E6AP complex to rescue p53 and induce apoptosis in cervical cancers.

    Directory of Open Access Journals (Sweden)

    Ying Zhou

    Full Text Available BACKGROUND: Our previous studies showed a down-regulation of GRIM-19 in primary human cervical cancers, and restoration of GRIM-19 induced tumor regression. The induction of tumor suppressor protein p53 ubiquitination and degradation by E6 oncoportein of high risk-HPV through forming a stable complex with E6AP is considered as a critical mechanism for cervical tumor development. The aims of this study were to determine the potential role of GRIM-19 in rescuing p53 protein and inducing cervical cancer cell apoptosis. METHODOLOGY/PRINCIPAL FINDINGS: The protein levels of GRIM-19 and p53 were detected in normal cervical tissues from 45 patients who underwent hysterectomy for reasons other than neoplasias of either the cervix or endometrium, and cervical cancer tissues from 60 patients with non-metastatic squamous epithelial carcinomas. Coimmunoprecipitation and GST pull-down assay were performed to examine the interaction of GRIM-19 with 18E6 and E6AP in vivo and in vitro respectively. The competition of 18E6 with E6AP in binding GRIM-19 by performing competition pull-down assays was designed to examine the disruption of E6/E6AP complex by GRIM-19. The augment of E6AP ubiquitination by GRIM-19 was detected in vivo and in vitro ubiquitination assay. The effects of GRIM-19-dependent p53 accumulation on cell proliferation, cell cycle, apoptosis were explored by MTT, flow cytometry and transmission electron microscopy respectively. The tumor suppression was detected by xenograft mouse model. CONCLUSION/SIGNIFICANCE: The levels of GRIM-19 and p53 were concurrently down regulated in cervical cancers. The restoration of GRIM-19 can induce ubiquitination and degradation of E6AP, and disrupt the E6/E6AP complex through the interaction of N-terminus of GRIM-19 with both E6 and E6AP, which protected p53 from degradation and promoted cell apoptosis. Tumor xenograft studies also revealed the suppression of p53 degradation in presence of GRIM-19. These data

  3. A high-throughput cellular assay to quantify the p53-degradation activity of E6 from different human papillomavirus types.

    Science.gov (United States)

    Gagnon, David; Archambault, Jacques

    2015-01-01

    A subset of human papillomaviruses (HPVs), known as the high-risk types, are the causative agents of cervical cancer and other malignancies of the anogenital region and oral mucosa. The capacity of these viruses to induce cancer and to immortalize cells in culture relies in part on a critical function of their E6 oncoprotein, that of promoting the poly-ubiquitination of the cellular tumor suppressor protein p53 and its subsequent degradation by the proteasome. Here, we describe a cellular assay to measure the p53-degradation activity of E6 from different HPV types. This assay is based on a translational fusion of p53 to Renilla luciferase (Rluc-p53) that remains sensitive to degradation by high-risk E6 and whose steady-state levels can be accurately measured in standard luciferase assays. The p53-degradation activity of any E6 protein can be tested and quantified in transiently transfected cells by determining the amount of E6-expression vector required to reduce by half the levels of RLuc-p53 luciferase activity (50 % effective concentration [EC50]). The high-throughput and quantitative nature of this assay makes it particularly useful to compare the p53-degradation activities of E6 from several HPV types in parallel.

  4. TFPI-2 is a putative tumor suppressor gene frequently inactivated by promoter hypermethylation in nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Wang, Shumin; Ma, Ning; Murata, Mariko; Huang, Guangwu; Zhang, Zhe; Xiao, Xue; Zhou, Xiaoying; Huang, Tingting; Du, Chunping; Yu, Nana; Mo, Yingxi; Lin, Longde; Zhang, Jinyan

    2010-01-01

    Epigenetic silencing of tumor suppressor genes play important roles in NPC tumorgenesis. Tissue factor pathway inhibitor-2 (TFPI-2), is a protease inhibitor. Recently, TFPI-2 was suggested to be a tumor suppressor gene involved in tumorigenesis and metastasis in some cancers. In this study, we investigated whether TFPI-2 was inactivated epigenetically in nasopharyngeal carcinoma (NPC). Transcriptional expression levels of TFPI-2 was evaluated by RT-PCR. Methylation status were investigated by methylation specific PCR and bisulfate genomic sequencing. The role of TFPI-2 as a tumor suppressor gene in NPC was addressed by re-introducing TFPI-2 expression into the NPC cell line CNE2. TFPI-2 mRNA transcription was inactivated in NPC cell lines. TFPI-2 was aberrantly methylated in 66.7% (4/6) NPC cell lines and 88.6% (62/70) of NPC primary tumors, but not in normal nasopharyngeal epithelia. TFPI-2 expression could be restored in NPC cells after demethylation treatment. Ectopic expression of TFPI-2 in NPC cells induced apoptosis and inhibited cell proliferation, colony formation and cell migration. Epigenetic inactivation of TFPI-2 by promoter hypermethylation is a frequent and tumor specific event in NPC. TFPI-2 might be considering as a putative tumor suppressor gene in NPC

  5. The role of UV induced lesions in skin carcinogenesis: an overview of oncogene and tumor suppressor gene modifications in xeroderma pigmentosum skin tumors

    International Nuclear Information System (INIS)

    Daya-Grosjean, Leela; Sarasin, Alain

    2005-01-01

    Xeroderma pigmentosum (XP), a rare hereditary syndrome, is characterized by a hypersensitivity to solar irradiation due to a defect in nucleotide excision repair resulting in a predisposition to squamous and basal cell carcinomas as well as malignant melanomas appearing at a very early age. The mutator phenotype of XP cells is evident by the higher levels of UV specific modifications found in key regulatory genes in XP skin tumors compared to those in the same tumor types from the normal population. Thus, XP provides a unique model for the study of unrepaired DNA lesions, mutations and skin carcinogenesis. The high l