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Sample records for sustaining mutant p53

  1. Mutant p53 interactions with supercoiled DNA

    Czech Academy of Sciences Publication Activity Database

    Brázdová, Marie; Němcová, Kateřina; Činčárová, Lenka; Šebest, Peter; Pivoňková, Hana; Brázda, Václav; Fojta, Miroslav; Paleček, Emil

    2007-01-01

    Roč. 24, č. 6 (2007), s. 639-640 ISSN 0739-1102. [Alban 2007: The 15th Conversation . 19.06.2007-23.06.2007, Albany] R&D Projects: GA MŠk(CZ) 1K04119; GA ČR(CZ) GP204/06/P369; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : mutant p53 * supercoiled DNA * cancer Subject RIV: BO - Biophysics

  2. 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)

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

    Science.gov (United States)

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

    2008-10-01

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

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

    Science.gov (United States)

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

    2017-05-01

    Although p53 protein aggregates have been observed in cancer cell lines and tumour tissue, their impact in cancer remains largely unknown. Here, we extensively screened for p53 aggregation phenotypes in tumour biopsies, and identified nuclear inclusion bodies (nIBs) of transcriptionally inactive mutant or wild-type p53 as the most frequent aggregation-like phenotype across six different cancer types. p53-positive nIBs co-stained with nuclear aggregation markers, and shared molecular hallmarks of nIBs commonly found in neurodegenerative disorders. In cell culture, tumour-associated stress was a strong inducer of p53 aggregation and nIB formation. This was most prominent for mutant p53, but could also be observed in wild-type p53 cell lines, for which nIB formation correlated with the loss of p53's transcriptional activity. Importantly, protein aggregation also fuelled the dysregulation of the proteostasis network in the tumour cell by inducing a hyperactivated, oncogenic heat-shock response, to which tumours are commonly addicted, and by overloading the proteasomal degradation system, an observation that was most pronounced for structurally destabilized mutant p53. Patients showing tumours with p53-positive nIBs suffered from a poor clinical outcome, similar to those with loss of p53 expression, and tumour biopsies showed a differential proteostatic expression profile associated with p53-positive nIBs. p53-positive nIBs therefore highlight a malignant state of the tumour that results from the interplay between (1) the functional inactivation of p53 through mutation and/or aggregation, and (2) microenvironmental stress, a combination that catalyses proteostatic dysregulation. This study highlights several unexpected clinical, biological and therapeutically unexplored parallels between cancer and neurodegeneration. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2016 Pathological Society of Great

  5. Mutant Mice Lacking the p53 C-Terminal Domain Model Telomere Syndromes

    NARCIS (Netherlands)

    Simeonova, I.; Jaber, S.; Draskovic, I.; Bardot, B.; Fang, M.; Bouarich-Bourimi, R.; Lejour, V.; Charbonnier, L.; Soudais, C.; Bourdon, J.C.; Huerre, M.; Londono-Vallejo, A.; Toledo, F.

    2013-01-01

    Mutations in p53, although frequent in human cancers, have not been implicated in telomere-related syndromes. Here, we show that homozygous mutant mice expressing p53(Delta31), a p53 lacking the C-terminal domain, exhibit increased p53 activity and suffer from aplastic anemia and pulmonary fibrosis,

  6. 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.

  7. Functional Significance of Mutant p53 in Breast Cancer

    National Research Council Canada - National Science Library

    O'Lear, Renee

    2001-01-01

    ... in those cells with irreparable damage. In human tumors, many hot-spot mutations are found within the DNA-binding domain of p53, rendering it incapable of sequence-specific transactivation of target genes such as p21, bax, and mdm2...

  8. Functional Significance of Mutant p53 in Breast Cancer

    National Research Council Canada - National Science Library

    O'Lear, Rene

    2002-01-01

    ... in those cells with irreparable damage. In human tumors, many hot-spot mutations are found within the DNA-binding domain of p53, rendering it incapable of sequence-specific transactivation of target genes such as p2l, bax, and mdm2...

  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. 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.

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

    Science.gov (United States)

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

    2015-01-01

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

  12. Mutant Mice Lacking the p53 C-Terminal Domain Model Telomere Syndromes

    Directory of Open Access Journals (Sweden)

    Iva Simeonova

    2013-06-01

    Full Text Available Mutations in p53, although frequent in human cancers, have not been implicated in telomere-related syndromes. Here, we show that homozygous mutant mice expressing p53Δ31, a p53 lacking the C-terminal domain, exhibit increased p53 activity and suffer from aplastic anemia and pulmonary fibrosis, hallmarks of syndromes caused by short telomeres. Indeed, p53Δ31/Δ31 mice had short telomeres and other phenotypic traits associated with the telomere disease dyskeratosis congenita and its severe variant the Hoyeraal-Hreidarsson syndrome. Heterozygous p53+/Δ31 mice were only mildly affected, but decreased levels of Mdm4, a negative regulator of p53, led to a dramatic aggravation of their symptoms. Importantly, several genes involved in telomere metabolism were downregulated in p53Δ31/Δ31 cells, including Dyskerin, Rtel1, and Tinf2, which are mutated in dyskeratosis congenita, and Terf1, which is implicated in aplastic anemia. Together, these data reveal that a truncating mutation can activate p53 and that p53 plays a major role in the regulation of telomere metabolism.

  13. Heterozygous inactivation of tsc2 enhances tumorigenesis in p53 mutant zebrafish

    Directory of Open Access Journals (Sweden)

    Seok-Hyung Kim

    2013-07-01

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

  14. Che-1 gene silencing induces osteosarcoma cell apoptosis by inhibiting mutant p53 expression

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ming; Wang, Dan, E-mail: danwangwdd@163.com; Li, Ning

    2016-04-22

    The transcriptional cofactor Che-1 is an RNA polymerase II (Pol II) which is involved in tumorigenesis, such as breast cancer and multiple myeloma. Che-1 can also regulate mutant p53 expression, which plays roles in many types of cancer. In this study, we aimed to investigate the effects and specific mechanism of Che-1 in the regulation of osteosarcoma (OS) cell growth. We found that Che-1 is highly expressed in several kinds of OS cells compared with osteoblast hFOB1.19 cells. MTT and flow cytometry assays showed that Che-1 depletion by siRNA markedly suppressed MG-63 and U2OS cell proliferation and promoted apoptosis. The chromatin immunoprecipitation (ChIP) assay verified the presence of Che-1 on the p53 promoter in MG-63 and U2OS cells carrying mutant p53. Further studies showed that Che-1 depletion inhibited mutant p53 expression. Notably, our study showed that the loss of Che-1 inhibits proliferation and promotes apoptosis in MG-63 cells by decreasing the level of mutant p53. Therefore, these findings open the possibility that silencing of Che-1 will have therapeutic benefit in OS. - Highlights: • Che-1 is highly expressed in several kinds of OS cells. • Che-1 depletion suppressed MG-63 and U2OS cell growth. • Che-1 is existed in the p53 promoter in MG-63 and U2OS cells. • Che-1 depletion inhibited mutant p53 expression. • Che-1 depletion inhibits cell growth by decreasing the level of mutant p53.

  15. Mutant p53 drives cancer by subverting multiple tumour suppression pathways

    Directory of Open Access Journals (Sweden)

    Sue eHaupt

    2016-01-01

    Full Text Available The tumour suppressor p53 normally acts as a brake to halt damaged cells from perpetrating their genetic errors into future generations. If p53 is disrupted by mutation, it may not only lose these corrective powers, but counter-productively acquire new capacities that drive cancer. A newly emerging manner in which mutant p53 executes its cancer promoting functions is by harnessing key proteins (including many transcription factors, which normally partner with its wild type, tumour-inhibiting counterpart. In association with the subverted activities of these protein partners, mutant p53 is empowered to act across multiple fundamental cellular pathways (regulating cell division and metabolism and corrupt them to become cancer promoting.

  16. 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.

  17. 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.

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

    Science.gov (United States)

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

    2014-07-23

    The scattering of light redirects and resonances when an electromagnetic wave interacts with electrons orbits in the hot spot core protein and oscillated electron of the gold nanoparticles (AuNP). This report demonstrates convincingly that resonant Rayleigh scattering generated from hot spot mutant p53 proteins is correspondence to cancer cells. Hot spot mutants have unique local electron density changes that affect specificity of DNA binding affinity compared with wild types. Rayleigh scattering changes introduced by hot-spot mutations were monitored by localized surface plasmon resonance (LSPR) shift changes. The LSPR λmax shift for hot-spot mutants ranged from 1.7 to 4.2 nm for mouse samples and from 0.64 nm to 2.66 nm for human samples, compared to 9.6 nm and 15 nm for wild type and mouse and human proteins, respectively with a detection sensitivity of p53 concentration at 17.9 nM. It is interesting that hot-spot mutants, which affect only interaction with DNA, launches affinitive changes as considerable as wild types. These changes propose that hot-spot mutants p53 proteins can be easily detected by local electron density alterations that disturbs the specificity of DNA binding of p53 core domain on the surface of the DNA probed-nanoplasmonic sensor. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. 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.

  20. Cyclophilin B Supports Myc and Mutant p53 Dependent Survival of Glioblastoma Multiforme Cells

    Science.gov (United States)

    Choi, Jae Won; Schroeder, Mark A.; Sarkaria, Jann N.; Bram, Richard J.

    2014-01-01

    Glioblastoma multiforme (GBM) is an aggressive, treatment-refractory type of brain tumor for which effective therapeutic targets remain important to identify. Here we report that cyclophilin B (CypB), a prolyl isomerase residing in the endoplasmic reticulum (ER), provides an essential survival signal in GBM cells. Analysis of gene expression databases revealed that CypB is upregulated in many cases of malignant glioma. We found that suppression of CypB reduced cell proliferation and survival in human GBM cells in vitro and in vivo. We also found that treatment with small molecule inhibitors of cyclophilins, including the approved drug cyclosporine, greatly reduced the viability of GBM cells. Mechanistically, depletion or pharmacologic inhibition of CypB caused hyperactivation of the oncogenic RAS-MAPK pathway, induction of cellular senescence signals, and death resulting from loss of MYC, mutant p53, Chk1 and JAK/STAT3 signaling. Elevated reactive oxygen species, ER expansion and abnormal unfolded protein responses in CypB-depleted GBM cells indicated that CypB alleviates oxidative and ER stresses and coordinates stress adaptation responses. Enhanced cell survival and sustained expression of multiple oncogenic proteins downstream of CypB may thus contribute to the poor outcome of GBM tumors. Our findings link chaperone-mediated protein folding in the ER to mechanisms underlying oncogenic transformation, and they make CypB an attractive and immediately targetable molecule for GBM therapy. PMID:24272483

  1. Cyclophilin B supports Myc and mutant p53-dependent survival of glioblastoma multiforme cells.

    Science.gov (United States)

    Choi, Jae Won; Schroeder, Mark A; Sarkaria, Jann N; Bram, Richard J

    2014-01-15

    Glioblastoma multiforme is an aggressive, treatment-refractory type of brain tumor for which effective therapeutic targets remain important to identify. Here, we report that cyclophilin B (CypB), a prolyl isomerase residing in the endoplasmic reticulum (ER), provides an essential survival signal in glioblastoma multiforme cells. Analysis of gene expression databases revealed that CypB is upregulated in many cases of malignant glioma. We found that suppression of CypB reduced cell proliferation and survival in human glioblastoma multiforme cells in vitro and in vivo. We also found that treatment with small molecule inhibitors of cyclophilins, including the approved drug cyclosporine, greatly reduced the viability of glioblastoma multiforme cells. Mechanistically, depletion or pharmacologic inhibition of CypB caused hyperactivation of the oncogenic RAS-mitogen-activated protein kinase pathway, induction of cellular senescence signals, and death resulting from loss of MYC, mutant p53, Chk1, and Janus-activated kinase/STAT3 signaling. Elevated reactive oxygen species, ER expansion, and abnormal unfolded protein responses in CypB-depleted glioblastoma multiforme cells indicated that CypB alleviates oxidative and ER stresses and coordinates stress adaptation responses. Enhanced cell survival and sustained expression of multiple oncogenic proteins downstream of CypB may thus contribute to the poor outcome of glioblastoma multiforme tumors. Our findings link chaperone-mediated protein folding in the ER to mechanisms underlying oncogenic transformation, and they make CypB an attractive and immediately targetable molecule for glioblastoma multiforme therapy.

  2. 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.

  3. Enhancement of P53-Mutant Human Colorectal Cancer Cells Radiosensitivity by Flavonoid Fisetin

    International Nuclear Information System (INIS)

    Chen Wenshu; Lee Yijang; Yu Yichu; Hsaio Chinghui

    2010-01-01

    Purpose: The aim of this study was to investigate whether fisetin is a potential radiosensitizer for human colorectal cancer cells, which are relatively resistant to radiotherapy. Methods and Materials: Cell survival was examined by clonogenic survival assay, and DNA fragmentation was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The effects of treatments on cell cycle distribution and apoptosis were examined by flow cytometry. Western blot analysis was performed to ascertain the protein levels of γ-H2AX, phospho-Chk2, active caspase-3, PARP cleavage, phospho-p38, phospho-AKT, and phospho-ERK1/2. Results: Fisetin pretreatment enhanced the radiosensitivity of p53-mutant HT-29 human colorectal cancer cells but not human keratocyte HaCaT cells; it also prolonged radiation-induced G 2 /M arrest, enhanced radiation-induced cell growth arrest in HT-29 cells, and suppressed radiation-induced phospho-H2AX (Ser-139) and phospho-Chk2 (Thr-68) in p53-mutant HT-29 cells. Pretreatment with fisetin enhanced radiation-induced caspase-dependent apoptosis in HT-29 cells. Fisetin pretreatment augmented radiation-induced phosphorylation of p38 mitogen-activated protein kinase, which is involved in caspase-mediated apoptosis, and SB202190 significantly reduced apoptosis and radiosensitivity in fisetin-pretreated HT-29 cells. By contrast, both phospho-AKT and phospho-ERK1/2, which are involved in cell proliferation and antiapoptotic pathways, were suppressed after irradiation combined with fisetin pretreatment. Conclusions: To our knowledge, this study is the first to provide evidence that fisetin exerts a radiosensitizing effect in p53-mutant HT-29 cells. Fisetin could potentially be developed as a novel radiosensitizer against radioresistant human cancer cells.

  4. [The Expression of Pokemon in Endometrial Carcinoma Tissue and the Correlation with Mutant p53].

    Science.gov (United States)

    Yi, Tian-jin; Wang, Ping

    2016-05-01

    To detect the expression of Pokemon in endometrial carcinoma (EC), to provide preliminary theoretical basis for clarifying pathogenesis and searching for effective targets. Ninety-eight cases of endometrial tissue paraffin specimens form July 2012 to July 2014 in West China Second University Hospital, Sichuan University, were collected, including: EC group, consisting of adenocarcinoma 23 cases, adenosquamous 12 cases, serous 3 cases, mucinous 11 cases and clear cell 9 cases, and control group, consisting of atypical hyperplasia endometrium 20 cases and normal endometrium 20 cases (secretory 10 cases, hyperplasia 10 cases). Immunohistochemistry was used to detect the expression of Pokemonin each section, analyzing the correlation of Pokemon expression with clinicopathologic characteristics and p53 expression. The positive rate of Pokemon in normal endometrium was 25% (5/20), significantly lower than that in atypical hyperplasia endometrium (60.0%, 12/20) and EC (93.1%, 54/58) (P Pokemon in III-IV stage, type II and Ki-67 ≥ 50 EC tissue was much higher (P = 0.012, 0.023, 0.029). In type II EC tissue, the correlation index between Pokemon and p53 is 0.669 (P = 0.000). The over expression of Pokemon upregulates the expression of mutant p53, which may be one of the carcinogenesis modes in type II EC.

  5. 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.

  6. Elevated expression of ribosomal protein genes L37, RPP-1, and S2 in the presence of mutant p53.

    Science.gov (United States)

    Loging, W T; Reisman, D

    1999-11-01

    The wild-type p53 protein is a DNA-binding transcription factor that activates genes such as p21, MDM2, GADD45, and Bax that are required for the regulation of cell cycle progression or apoptosis in response to DNA damage. Mutant forms of p53, which are transforming oncogenes and are expressed at high levels in tumor cells, generally have a reduced binding affinity for the consensus DNA sequence. Interestingly, some p53 mutants that are no longer effective at binding to the consensus DNA sequence and transactivating promoters containing this target site have acquired the ability to transform cells in culture, in part through their ability to transactivate promoters of a number of genes that are not targets of the wild-type protein. Certain p53 mutants are therefore considered to be gain-of-function mutants and appear to be promoting proliferation or transforming cells through their ability to alter the expression of novel sets of genes. Our goal is to identify genes that have altered expression in the presence of a specific mutant p53 (Arg to Trp mutation at codon 248) protein. Through examining differential gene expression in cells devoid of p53 expression and in cells that express high levels of mutant p53 protein, we have identified three ribosomal protein genes that have elevated expression in response to mutant p53. Consistent with these findings, the overexpression of a number of ribosomal protein genes in human tumors and evidence for their contribution to oncogenic transformation have been reported previously, although the mechanism leading to this overexpression has remained elusive. We show results that indicate that expression of these specific ribosomal protein genes is increased in the presence of the R248W p53 mutant, which provides a mechanism for their overexpression in human tumors.

  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. Functional characterization of a new p53 mutant generated by homozygous deletion in a neuroblastoma cell line

    International Nuclear Information System (INIS)

    Nakamura, Yohko; Ozaki, Toshinori; Niizuma, Hidetaka; Ohira, Miki; Kamijo, Takehiko; Nakagawara, Akira

    2007-01-01

    p53 is a key modulator of a variety of cellular stresses. In human neuroblastomas, p53 is rarely mutated and aberrantly expressed in cytoplasm. In this study, we have identified a novel p53 mutant lacking its COOH-terminal region in neuroblastoma SK-N-AS cells. p53 accumulated in response to cisplatin (CDDP) and thereby promoting apoptosis in neuroblastoma SH-SY5Y cells bearing wild-type p53, whereas SK-N-AS cells did not undergo apoptosis. We found another p53 (p53ΔC) lacking a part of oligomerization domain and nuclear localization signals in SK-N-AS cells. p53ΔC was expressed largely in cytoplasm and lost the transactivation function. Furthermore, a 3'-part of the p53 locus was homozygously deleted in SK-N-AS cells. Thus, our present findings suggest that p53 plays an important role in the DNA-damage response in certain neuroblastoma cells and it seems to be important to search for p53 mutations outside DNA-binding domain

  9. Proteomics Characterization of the Molecular Mechanisms of Mutant P53 Reactivation with PRIMA-1 in Breast Cancer Cells

    National Research Council Canada - National Science Library

    Daoud, Sayed S

    2006-01-01

    The main purpose of the study is to identify novel protein-protein interactions in various locations of cells to establish the molecular mechanisms of mutant p53 reactivation with PRIMA-1 in breast cancer cells...

  10. Ser46 phosphorylation and prolyl-isomerase Pin1-mediated isomerization of p53 are key events in p53-dependent apoptosis induced by mutant huntingtin.

    Science.gov (United States)

    Grison, Alice; Mantovani, Fiamma; Comel, Anna; Agostoni, Elena; Gustincich, Stefano; Persichetti, Francesca; Del Sal, Giannino

    2011-11-01

    Huntington disease (HD) is a neurodegenerative disorder caused by a CAG repeat expansion in the gene coding for huntingtin protein. Several mechanisms have been proposed by which mutant huntingtin (mHtt) may trigger striatal neurodegeneration, including mitochondrial dysfunction, oxidative stress, and apoptosis. Furthermore, mHtt induces DNA damage and activates a stress response. In this context, p53 plays a crucial role in mediating mHtt toxic effects. Here we have dissected the pathway of p53 activation by mHtt in human neuronal cells and in HD mice, with the aim of highlighting critical nodes that may be pharmacologically manipulated for therapeutic intervention. We demonstrate that expression of mHtt causes increased phosphorylation of p53 on Ser46, leading to its interaction with phosphorylation-dependent prolyl isomerase Pin1 and consequent dissociation from the apoptosis inhibitor iASPP, thereby inducing the expression of apoptotic target genes. Inhibition of Ser46 phosphorylation by targeting homeodomain-interacting protein kinase 2 (HIPK2), PKCδ, or ataxia telangiectasia mutated kinase, as well as inhibition of the prolyl isomerase Pin1, prevents mHtt-dependent apoptosis of neuronal cells. These results provide a rationale for the use of small-molecule inhibitors of stress-responsive protein kinases and Pin1 as a potential therapeutic strategy for HD treatment.

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Arindam Datta

    2016-06-01

    Full Text Available Mutation in TP53 is a common genetic alteration in human cancers. Certain tumor associated p53 missense mutants acquire gain-of-function (GOF properties and confer oncogenic phenotypes including enhanced chemoresistance. The colorectal cancers (CRC harboring mutant p53 are generally aggressive in nature and difficult to treat. To identify a potential gene expression signature of GOF mutant p53-driven acquired chemoresistance in CRC, we performed transcriptome profiling of floxuridine (FUdR treated SW480 cells expressing mutant p53R273H (GEO#: GSE77533. We obtained several genes differentially regulated between FUdR treated and untreated cells. Further, functional characterization and pathway analysis revealed significant enrichment of crucial biological processes and pathways upon FUdR treatment in SW480 cells. Our data suggest that in response to chemotherapeutics treatment, cancer cells with GOF mutant p53 can modulate key cellular pathways to withstand the cytotoxic effect of the drugs. The genes and pathways identified in the present study can be further validated and targeted for better chemotherapy response in colorectal cancer patients harboring mutant p53.

  13. 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

  14. Human T-Cell Leukemia Virus I Tax Protein Sensitizes p53-Mutant Cells to DNA Damage

    Science.gov (United States)

    Mihaylova, Valia T.; Green, Allison M.; Khurgel, Moshe; Semmes, Oliver J.; Kupfer, Gary M.

    2018-01-01

    Mutations in p53 are a common cause of resistance of cancers to standard chemotherapy and, thus, treatment failure. Reports have shown that Tax, a human T-cell leukemia virus type I encoded protein that has been associated with genomic instability and perturbation of transcription and cell cycle, sensitizes HeLa cells to UV treatment. The extent to which Tax can sensitize cells and the mechanism by which it exerts its effect are unknown. In this study, we show that Tax sensitizes p53-mutant cells to a broad range of DNA-damaging agents, including mitomycin C, a bifunctional alkylator, etoposide, a topoisomerase II drug, and UV light, but not ionizing radiation, a double-strand break agent, or vinblastine, a tubulin poison. Tax caused hypersensitivity in all p53-deleted cell lines and several, but not all, mutant-expressed p53–containing cell lines, while unexpectedly being protective in p53 wild-type (wt) cells. The effect observed in p53-deleted lines could be reversed for this by transfection of wt p53. We also show that Tax activates a p53-independent proapoptotic program through decreased expression of the retinoblastoma protein and subsequent increased E2F1 expression. The expression of several proapoptotic proteins was also induced by Tax, including Puma and Noxa, culminating in a substantial increase in Bax dimerization. Our results show that Tax can sensitize p53-mutant cells to DNA damage while protecting p53 wt cells, a side benefit that might result in reduced toxicity in normal cells. Such studies hold the promise of a novel adjunctive therapy that could make cancer chemotherapy more effective. PMID:18559532

  15. 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.

  16. 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.

  17. Prediction of P53 mutants (multiple sites transcriptional activity based on structural (2D&3D properties.

    Directory of Open Access Journals (Sweden)

    R Geetha Ramani

    Full Text Available Prediction of secondary site mutations that reinstate mutated p53 to normalcy has been the focus of intense research in the recent past owing to the fact that p53 mutants have been implicated in more than half of all human cancers and restoration of p53 causes tumor regression. However laboratory investigations are more often laborious and resource intensive but computational techniques could well surmount these drawbacks. In view of this, we formulated a novel approach utilizing computational techniques to predict the transcriptional activity of multiple site (one-site to five-site p53 mutants. The optimal MCC obtained by the proposed approach on prediction of one-site, two-site, three-site, four-site and five-site mutants were 0.775,0.341,0.784,0.916 and 0.655 respectively, the highest reported thus far in literature. We have also demonstrated that 2D and 3D features generate higher prediction accuracy of p53 activity and our findings revealed the optimal results for prediction of p53 status, reported till date. We believe detection of the secondary site mutations that suppress tumor growth may facilitate better understanding of the relationship between p53 structure and function and further knowledge on the molecular mechanisms and biological activity of p53, a targeted source for cancer therapy. We expect that our prediction methods and reported results may provide useful insights on p53 functional mechanisms and generate more avenues for utilizing computational techniques in biological data analysis.

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

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  19. 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.

  20. Mutant p53 perturbs DNA replication checkpoint control through TopBP1 and Treslin.

    Science.gov (United States)

    Liu, Kang; Lin, Fang-Tsyr; Graves, Joshua D; Lee, Yu-Ju; Lin, Weei-Chin

    2017-05-09

    Accumulating evidence supports the gain-of-function of mutant forms of p53 (mutp53s). However, whether mutp53 directly perturbs the DNA replication checkpoint remains unclear. Previously, we have demonstrated that TopBP1 forms a complex with mutp53s and mediates their gain-of-function through NF-Y and p63/p73. Akt phosphorylates TopBP1 and induces its oligomerization, which inhibits its ATR-activating function. Here we show that various contact and conformational mutp53s bypass Akt to induce TopBP1 oligomerization and attenuate ATR checkpoint response during replication stress. The effect on ATR response caused by mutp53 can be exploited in a synthetic lethality strategy, as depletion of another ATR activator, DNA2, in mutp53-R273H-expressing cancer cells renders cells hypersensitive to cisplatin. Expression of mutp53-R273H also makes cancer cells more sensitive to DNA2 depletion or DNA2 inhibitors. In addition to ATR-activating function during replication stress, TopBP1 interacts with Treslin in a Cdk-dependent manner to initiate DNA replication during normal growth. We find that mutp53 also interferes with TopBP1 replication function. Several contact, but not conformational, mutp53s enhance the interaction between TopBP1 and Treslin and promote DNA replication despite the presence of a Cdk2 inhibitor. Together, these data uncover two distinct mechanisms by which mutp53 enhances DNA replication: ( i ) Both contact and conformational mutp53s can bind TopBP1 and attenuate the checkpoint response to replication stress, and ( ii ) during normal growth, contact (but not conformational) mutp53s can override the Cdk2 requirement to promote replication by facilitating the TopBP1/Treslin interaction.

  1. Delayed expression of apoptosis in X-irradiated human leukemic MOLT-4 cells transfected with mutant p53

    International Nuclear Information System (INIS)

    Nakano, Hisako; Yonekawa, Hiromichi; Shinohara, Kunio

    2003-01-01

    The effects of X-rays on cell survival, apoptosis, and long-term response in the development of cell death as measured by the dye exclusion test were studied in human leukemic MOLT-4 cells (p53 wild-type) stably transfected with a mutant p53 cDNA expression vector. Cell survival, as determined from colony-forming ability, was increased in an expression level dependent manner, but the increase was partial even with the highest-expressing clone (B3). This contrasts with the prior observation that cell death and apoptosis in B3 are completely inhibited at 24 h after irradiation with 1.8 Gy of X-rays. The examination of B3 cells incubated for longer than 24 h after X-irradiation showed a delay in the induction of cell death and apoptosis. Western blot analysis revealed that the time required to reach the highest level of wild-type p53 protein in B3 was longer than the time in MOLT-4 and that the p53 may be stabilized by the phosphorylation at Ser-15. These results suggest that the introduction of mutant p53 into MOLT-4 merely delays the development of apoptosis, during which the cells could repair the damage induced by X-rays, and results in the partial increase in cell survival. (author)

  2. Use of a temperature-sensitive p53 mutant to evaluate mechanisms of 5-fluorodeoxyuridine-mediated radiosensitization

    International Nuclear Information System (INIS)

    Naida, J.D.; Davis, M.A.; Lawrence, T.S.

    1996-01-01

    Purpose/Objective: Evidence exists that fluorodeoxyuridine (FdUrd)-mediated radiosensitization occurs in HT29 human colon carcinoma cells (which are p53 mutant) when these cells progress past the G 1 /S boundary in the presence of the drug. It has been demonstrated that wild type p53 levels increase following fluoropyrimidine treatment and that G 1 arrest is associated with increased p53 levels. We hypothesized that the restoration of wild type p53 function might restore G 1 /S arrest after FdUrd treatment, and that this would prevent FdUrd-mediated radiosensitization. Similarly, we hypothesized that cells containing wild type p53 would not be radiosensitized by FdUrd. Materials and Methods: Two clones of HT29 human colon cancer cells (ts29-A and ts29-G) containing murine temperature-sensitive p53 were constructed using electroporation and Geneticin selection. Incubation of these cells at the permissive temperature of 32 deg. C produces wild type p53 function and at the non permissive temperature of 38 deg. C causes mutant p53 function. A G418 resistant control cell line was also constructed (HT29neo). Cells were incubated at either 32 deg. C or 38 deg. C for 24 hours prior to irradiation and with FdUrd (100 nM) or medium only during the last 14 hours of the temperature shift. To assess progression into S phase, single-parameter (propidium iodide (PI)) and two-parameter (PI and bromodeoxyuridine) flow cytometry were performed at the end of drug exposure. A standard clonogenic assay was used. Results: We found that when ts29-A and ts29-G cells were incubated at the non-permissive (inactive p53 conformation) temperature, they progressed into S phase following exposure to FdUrd and were radiosensitized (enhancement ratio 1.5) to a degree similar to that seen in parental HT29 cells. Cells incubated at the permissive (wild-type p53 conformation) temperature demonstrated G 1 arrest, S phase depletion, and G2 arrest. In addition, FdUrd-mediated radiosensitization was

  3. Mutant p53 transfection of astrocytic cells results in altered cell cycle control, radiation sensitivity, and tumorigenicity

    International Nuclear Information System (INIS)

    Kanady, Kirk E.; Mei Su; Proulx, Gary; Malkin, David M.; Pardo, Francisco S.

    1995-01-01

    Introduction: Alterations in the p53 tumor suppressor gene are one of the most frequent genetic alterations in malignant gliomas. An understanding of the molecular genetic events leading to glial tumor progression would aid in designing therapeutic vectors for controlling these challenging tumor types. We investigated whether mutations in coding exons of the p53 gene result in functional changes altering cell cycle 'checkpoint' control and the intrinsic radiation sensitivity of glial cells. Methods: An astrocytic cell line was derived from a low grade astrocytoma and characterized to be of human karyotype and GFAP positivity. Additionally, the cellular population has never formed tumors in immune-deficient mice. At early passage ( 2 as parameters. Cell kinetic analyses after 2, 5, and 10 Gy of ionizing radiation were conducted using propidium iodide FACS analyses. Results: Overall levels of p53 expression were increased 5-10 fold in the transfected cellular populations. Astrocytic cellular populations transfected with mutant p53 revealed a statistically significant increase in levels of resistance to ionizing radiation in vitro (2-tailed test, SF2, MID). Astrocytic cellular populations transfected with mutant p53, unlike the parental cells, were tumorigenic in SCID mice. Cell kinetic analyses indicated that the untransfected cell line demonstrated dose dependent G1 and G2 arrests. Following transfection, however, the resultant cellular population demonstrated a predominant G2 arrest. Conclusions: Astrocytic cellular populations derived from low grade astrocytomas, are relatively radiation sensitive, non-tumorigenic, and have intact cell cycle ''checkpoints.'' Cellular populations resulting upon transfection of parental cells with a dominant negative p53 mutation, are relatively radiation resistant, when compared to both parental and mock-transfected cells. Transfected cells demonstrate abnormalities of cell cycle control at the G1/S checkpoint, increases in levels

  4. Infection with E1B-mutant adenovirus stabilizes p53 but blocks p53 acetylation and activity through E1A

    DEFF Research Database (Denmark)

    Savelyeva, I.; Dobbelstein, M.

    2011-01-01

    to the suppression of p21 transcription. Depending on the E1A conserved region 3, E1B-defective adenovirus impaired the ability of the transcription factor Sp1 to bind the p21 promoter. Moreover, the amino terminal region of E1A, binding the acetyl transferases p300 and CREB-binding protein, blocked p53 K382...... accumulation of p53, without obvious defects in p53 localization, phosphorylation, conformation and oligomerization. Nonetheless, p53 completely failed to induce its target genes in this scenario, for example, p21/CDKN1A, Mdm2 and PUMA. Two regions of the E1A gene products independently contributed...... acetylation in infected cells. Mutating either of these E1A regions, in addition to E1B, partially restored p21 mRNA levels. Our findings argue that adenovirus attenuates p53-mediated p21 induction, through at least two E1B-independent mechanisms. Other virus species and cancer cells may employ analogous...

  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. Detection of single nucleotide polymorphisms in p53 mutation hotspots and expression of mutant p53 in human cell lines using an enzyme-linked electrochemical assay

    Czech Academy of Sciences Publication Activity Database

    Horáková Brázdilová, Petra; Šimková, Eva; Vychodilová, Zdenka; Brázdová, Marie; Fojta, Miroslav

    2009-01-01

    Roč. 21, č. 15 (2009), s. 1723-1729 ISSN 1040-0397 R&D Projects: GA ČR(CZ) GA203/07/1195; GA AV ČR(CZ) IAA400040901; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : enzyme-linked electrochemical assay * SNP typing * p53 mutation Subject RIV: AQ - Safety, Health Protection, Human - Machine Impact factor: 2.630, year: 2009

  7. 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....

  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. p53 constrains progression to anaplastic thyroid carcinoma in a Braf-mutant mouse model of papillary thyroid cancer

    Science.gov (United States)

    McFadden, David G.; Vernon, Amanda; Santiago, Philip M.; Martinez-McFaline, Raul; Bhutkar, Arjun; Crowley, Denise M.; McMahon, Martin; Sadow, Peter M.; Jacks, Tyler

    2014-01-01

    Anaplastic thyroid carcinoma (ATC) has among the worst prognoses of any solid malignancy. The low incidence of the disease has in part precluded systematic clinical trials and tissue collection, and there has been little progress in developing effective therapies. v-raf murine sarcoma viral oncogene homolog B (BRAF) and tumor protein p53 (TP53) mutations cooccur in a high proportion of ATCs, particularly those associated with a precursor papillary thyroid carcinoma (PTC). To develop an adult-onset model of BRAF-mutant ATC, we generated a thyroid-specific CreER transgenic mouse. We used a Cre-regulated BrafV600E mouse and a conditional Trp53 allelic series to demonstrate that p53 constrains progression from PTC to ATC. Gene expression and immunohistochemical analyses of murine tumors identified the cardinal features of human ATC including loss of differentiation, local invasion, distant metastasis, and rapid lethality. We used small-animal ultrasound imaging to monitor autochthonous tumors and showed that treatment with the selective BRAF inhibitor PLX4720 improved survival but did not lead to tumor regression or suppress signaling through the MAPK pathway. The combination of PLX4720 and the mapk/Erk kinase (MEK) inhibitor PD0325901 more completely suppressed MAPK pathway activation in mouse and human ATC cell lines and improved the structural response and survival of ATC-bearing animals. This model expands the limited repertoire of autochthonous models of clinically aggressive thyroid cancer, and these data suggest that small-molecule MAPK pathway inhibitors hold clinical promise in the treatment of advanced thyroid carcinoma. PMID:24711431

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

    Science.gov (United States)

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

    2017-09-01

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

  11. A Sensitive and Specific Diagnostic Panel to Distinguish Diffuse Astrocytoma from Astrocytosis: Chromosome 7 Gain with Mutant Isocitrate Dehydrogenase 1 and p53

    Science.gov (United States)

    Camelo-Piragua, Sandra; Jansen, Michael; Ganguly, Aniruddha; Kim, J. ChulMin; Cosper, Arjola K.; Dias-Santagata, Dora; Nutt, Catherine L.; Iafrate, A. John; Louis, David N.

    2011-01-01

    One of the major challenges of surgical neuropathology is the distinction of diffuse astrocytoma (World Health Organization [WHO] grade II) from astrocytosis. The most commonly used ancillary tool to solve this problem is p53 immunohistochemistry (IHC), but this is neither sensitive nor specific. Isocitrate dehydrogenase 1 (IDH1) mutations are common in lower grade gliomas, with most causing a specific amino acid change (R132H) that can be detected with a monoclonal antibody. IDH2 mutations are rare, but also occur in gliomas. In addition, gains of chromosome 7 are common in gliomas. In this study we assessed the status of p53, IDH1/2 and chromosome 7 to determine the most useful panel to distinguish astrocytoma from astrocytosis. We studied biopsy specimens from 21 WHO grade II diffuse astrocytomas and 20 reactive conditions. The single most sensitive test to identify astrocytoma is fluorescence in situ hybridization (FISH) for chromosome 7 gain (76.2%). The combination of p53 and mutant IDH1 IHC provides a higher sensitivity (71.4%) than either test alone (47.8%); this combination offers a practical initial approach for the surgical pathologist. The best overall sensitivity (95%) is achieved when FISH for chromosome 7 gain is added to the p53-mutant IDH1 IHC panel. PMID:21343879

  12. Effects of temperature on the p53-DNA binding interactions and their dynamical behavior: comparing the wild type to the R248Q mutant.

    Directory of Open Access Journals (Sweden)

    Khaled Barakat

    Full Text Available BACKGROUND: The protein p53 plays an active role in the regulation of cell cycle. In about half of human cancers, the protein is inactivated by mutations located primarily in its DNA-binding domain. Interestingly, a number of these mutations possess temperature-induced DNA-binding characteristics. A striking example is the mutation of Arg248 into glutamine or tryptophan. These mutants are defective for binding to DNA at 310 K although they have been shown to bind specifically to several p53 response elements at sub-physiological temperatures (298-306 K. METHODOLOGY/PRINCIPAL FINDINGS: This important experimental finding motivated us to examine the effects of temperature on the structure and configuration of R248Q mutant and compare it to the wild type protein. Our aim is to determine how and where structural changes of mutant variants take place due to temperature changes. To answer these questions, we compared the mutant to the wild-type proteins from two different aspects. First, we investigated the systems at the atomistic level through their DNA-binding affinity, hydrogen bond networks and spatial distribution of water molecules. Next, we assessed changes in their long-lived conformational motions at the coarse-grained level through the collective dynamics of their side-chain and backbone atoms separately. CONCLUSIONS: The experimentally observed effect of temperature on the DNA-binding properties of p53 is reproduced. Analysis of atomistic and coarse-grained data reveal that changes in binding are determined by a few key residues and provide a rationale for the mutant-loss of binding at physiological temperatures. The findings can potentially enable a rescue strategy for the mutant structure.

  13. Preferential Binding of Hot Spot Mutant p53 Proteins to Supercoiled DNA In Vitro and in Cells

    Czech Academy of Sciences Publication Activity Database

    Brázdová, Marie; Navrátilová, Lucie; Tichý, Vlastimil; Němcová, Kateřina; Lexa, M.; Hrstka, R.; Pečinka, Petr; Adámik, Matěj; Vojtěšek, B.; Paleček, Emil; Deppert, W.; Fojta, Miroslav

    2013-01-01

    Roč. 8, č. 3 (2013), e59567 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GAP301/10/2370; GA ČR GA13-36108S; GA ČR(CZ) GP204/06/P369; GA ČR(CZ) GA204/08/1560; GA ČR(CZ) GAP301/11/2055; GA MŠk(CZ) 1K04119 Grant - others:GA ČR(CZ) GAP301/11/1678 Institutional research plan: CEZ:AV0Z50040702 Keywords : TUMOR-SUPPRESSOR P53 * C-TERMINAL DOMAIN * OF-FUNCTION MUTATIONS Subject RIV: BO - Biophysics Impact factor: 3.534, year: 2013

  14. Topical grape seed proanthocyandin extract reduces sunburn cells and mutant p53 positive epidermal cell formation, and prevents depletion of Langerhans cells in an acute sunburn model.

    Science.gov (United States)

    Yuan, Xiao-Ying; Liu, Wei; Hao, Jian-Chun; Gu, Wei-Jie; Zhao, Yan-Shuang

    2012-01-01

    The purpose of this study was to investigate whether grape seed proanthocyanidin extract (GSPE) can provide photoprotection against ultraviolet (UV) irradiation. Study has shown that GSPE is a natural oxidant, and is used in many fields such as ischemia-reperfusion injury, chronic pancreatitis, and even cancer. However, the effect of GSPE on UV irradiation is as yet unknown. Cutaneous areas on the backs of normal volunteers were untreated or treated with GSPE solutions or vehicles 30 min before exposure to two minimal erythema doses (MED) of solar simulated radiation. Cutaneous areas at different sites were examined histologically for the number of sunburn cells, or immunohistochemically for Langerhans cells and mutant p53 epidermal cells. On histological and immunohistochemical examination, skin treated with GSPE before UV radiation showed fewer sunburn cells and mutant p53-positive epidermal cells and more Langerhans cells compared with skin treated with 2-MED UV radiation only (p<0.001, p<0.001, and p<0.01, respectively). GSPE may be a possible preventive agent for photoprotection.

  15. p53 mutations promote proteasomal activity.

    Science.gov (United States)

    Oren, Moshe; Kotler, Eran

    2016-07-27

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

  16. Dual targeting of wild-type and mutant p53 by small molecule RITA results in the inhibition of N-Myc and key survival oncogenes and kills neuroblastoma cells in vivo and in vitro.

    Science.gov (United States)

    Burmakin, Mikhail; Shi, Yao; Hedström, Elisabeth; Kogner, Per; Selivanova, Galina

    2013-09-15

    Restoration of the p53 function in tumors is a promising therapeutic strategy due to the high potential of p53 as tumor suppressor and the fact that established tumors depend on p53 inactivation for their survival. Here, we addressed the question whether small molecule RITA can reactivate p53 in neuroblastoma and suppress the growth of neuroblastoma cells in vitro and in vivo. The ability of RITA to inhibit growth and to induce apoptosis was shown in seven neuroblastoma cell lines. Mechanistic studies were carried out to determine the p53 dependence and the molecular mechanism of RITA-induced apoptosis in neuroblastoma, using cell viability assays, RNAi silencing, co-immunoprecipitation, qPCR, and Western blotting analysis. In vivo experiments were conducted to study the effect of RITA on human neuroblastoma xenografts in mice. RITA induced p53-dependent apoptosis in a set of seven neuroblastoma cell lines, carrying wild-type or mutant p53; it activated p53 and triggered the expression of proapoptotic p53 target genes. Importantly, p53 activated by RITA inhibited several key oncogenes that are high-priority targets for pharmacologic anticancer strategies in neuroblastoma, including N-Myc, Aurora kinase, Mcl-1, Bcl-2, Wip-1, MDM2, and MDMX. Moreover, RITA had a strong antitumor effect in vivo. Reactivation of wild-type and mutant p53 resulting in the induction of proapoptotic factors along with ablation of key oncogenes by compounds such as RITA may be a highly effective strategy to treat neuroblastoma. ©2013 AACR.

  17. p53 modulates the AMPK inhibitor compound C induced apoptosis in human skin cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shi-Wei [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Wu, Chun-Ying [Division of Gastroenterology and Hepatology, Taichung Veterans General Hospital, Taichung, Taiwan (China); Wang, Yen-Ting [Department of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan (China); Kao, Jun-Kai [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Department of Pediatrics, Children' s Hospital, Changhua Christian Hospital, Changhua, Taiwan (China); Lin, Chi-Chen; Chang, Chia-Che; Mu, Szu-Wei; Chen, Yu-Yu [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Chiu, Husan-Wen [Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan (China); Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan (China); Chang, Chuan-Hsun [Department of Surgical Oncology, Cheng Hsin General Hospital, Taipei, Taiwan (China); Department of Nutrition Therapy, Cheng Hsin General Hospital, Taipei, Taiwan (China); School of Nutrition and Health Sciences, Taipei Medical University, Taipei, Taiwan (China); Liang, Shu-Mei [Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan (China); Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan (China); Chen, Yi-Ju [Department of Dermatology, Taichung Veterans General Hospital, Taichung, Taiwan (China); Huang, Jau-Ling [Department of Bioscience Technology, Chang Jung Christian University, Tainan, Taiwan (China); Shieh, Jeng-Jer, E-mail: shiehjj@vghtc.gov.tw [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan (China)

    2013-02-15

    Compound C, a well-known inhibitor of the intracellular energy sensor AMP-activated protein kinase (AMPK), has been reported to cause apoptotic cell death in myeloma, breast cancer cells and glioma cells. In this study, we have demonstrated that compound C not only induced autophagy in all tested skin cancer cell lines but also caused more apoptosis in p53 wildtype skin cancer cells than in p53-mutant skin cancer cells. Compound C can induce upregulation, phosphorylation and nuclear translocalization of the p53 protein and upregulate expression of p53 target genes in wildtype p53-expressing skin basal cell carcinoma (BCC) cells. The changes of p53 status were dependent on DNA damage which was caused by compound C induced reactive oxygen species (ROS) generation and associated with activated ataxia-telangiectasia mutated (ATM) protein. Using the wildtype p53-expressing BCC cells versus stable p53-knockdown BCC sublines, we present evidence that p53-knockdown cancer cells were much less sensitive to compound C treatment with significant G2/M cell cycle arrest and attenuated the compound C-induced apoptosis but not autophagy. The compound C induced G2/M arrest in p53-knockdown BCC cells was associated with the sustained inactive Tyr15 phosphor-Cdc2 expression. Overall, our results established that compound C-induced apoptosis in skin cancer cells was dependent on the cell's p53 status. - Highlights: ► Compound C caused more apoptosis in p53 wildtype than p53-mutant skin cancer cells. ► Compound C can upregulate p53 expression and induce p53 activation. ► Compound C induced p53 effects were dependent on ROS induced DNA damage pathway. ► p53-knockdown attenuated compound C-induced apoptosis but not autophagy. ► Compound C-induced apoptosis in skin cancer cells was dependent on p53 status.

  18. p53 modulates the AMPK inhibitor compound C induced apoptosis in human skin cancer cells

    International Nuclear Information System (INIS)

    Huang, Shi-Wei; Wu, Chun-Ying; Wang, Yen-Ting; Kao, Jun-Kai; Lin, Chi-Chen; Chang, Chia-Che; Mu, Szu-Wei; Chen, Yu-Yu; Chiu, Husan-Wen; Chang, Chuan-Hsun; Liang, Shu-Mei; Chen, Yi-Ju; Huang, Jau-Ling; Shieh, Jeng-Jer

    2013-01-01

    Compound C, a well-known inhibitor of the intracellular energy sensor AMP-activated protein kinase (AMPK), has been reported to cause apoptotic cell death in myeloma, breast cancer cells and glioma cells. In this study, we have demonstrated that compound C not only induced autophagy in all tested skin cancer cell lines but also caused more apoptosis in p53 wildtype skin cancer cells than in p53-mutant skin cancer cells. Compound C can induce upregulation, phosphorylation and nuclear translocalization of the p53 protein and upregulate expression of p53 target genes in wildtype p53-expressing skin basal cell carcinoma (BCC) cells. The changes of p53 status were dependent on DNA damage which was caused by compound C induced reactive oxygen species (ROS) generation and associated with activated ataxia-telangiectasia mutated (ATM) protein. Using the wildtype p53-expressing BCC cells versus stable p53-knockdown BCC sublines, we present evidence that p53-knockdown cancer cells were much less sensitive to compound C treatment with significant G2/M cell cycle arrest and attenuated the compound C-induced apoptosis but not autophagy. The compound C induced G2/M arrest in p53-knockdown BCC cells was associated with the sustained inactive Tyr15 phosphor-Cdc2 expression. Overall, our results established that compound C-induced apoptosis in skin cancer cells was dependent on the cell's p53 status. - Highlights: ► Compound C caused more apoptosis in p53 wildtype than p53-mutant skin cancer cells. ► Compound C can upregulate p53 expression and induce p53 activation. ► Compound C induced p53 effects were dependent on ROS induced DNA damage pathway. ► p53-knockdown attenuated compound C-induced apoptosis but not autophagy. ► Compound C-induced apoptosis in skin cancer cells was dependent on p53 status

  19. Hypoxia-Induced Cisplatin Resistance in Non-Small Cell Lung Cancer Cells Is Mediated by HIF-1α and Mutant p53 and Can Be Overcome by Induction of Oxidative Stress.

    Science.gov (United States)

    Deben, Christophe; Deschoolmeester, Vanessa; De Waele, Jorrit; Jacobs, Julie; Van den Bossche, Jolien; Wouters, An; Peeters, Marc; Rolfo, Christian; Smits, Evelien; Lardon, Filip; Pauwels, Patrick

    2018-04-21

    The compound APR-246 (PRIMA-1 MET ) is a known reactivator of (mutant) p53 and inducer of oxidative stress which can sensitize cancer cells to platinum-based chemotherapeutics. However, the effect of a hypoxic tumor environment has been largely overlooked in this interaction. This study focusses on the role of hypoxia-inducible factor-1α (HIF-1α) and the p53 tumor suppressor protein in hypoxia-induced cisplatin resistance in non-small cell lung cancer (NSCLC) cells and the potential of APR-246 to overcome this resistance. We observed that hypoxia-induced cisplatin resistance only occurred in the p53 mutant NCI-H2228 Q331 * cell line, and not in the wild type A549 and mutant NCI-H1975 R273H cell lines. Cisplatin reduced HIF-1α protein levels in NCI-H2228 Q331 * cells, leading to a shift in expression from HIF-1α-dependent to p53-dependent transcription targets under hypoxia. APR-246 was able to overcome hypoxia-induced cisplatin resistance in NCI-H2228 Q331 * cells in a synergistic manner without affecting mutant p53 Q331 * transcriptional activity, but significantly depleting total glutathione levels more efficiently under hypoxic conditions. Synergism was dependent on the presence of mutant p53 Q331 * and the induction of reactive oxygen species, with depletion of one or the other leading to loss of synergism. Our data further support the rationale of combining APR-246 with cisplatin in NSCLC, since their synergistic interaction is retained or enforced under hypoxic conditions in the presence of mutant p53.

  20. Hypoxia-Induced Cisplatin Resistance in Non-Small Cell Lung Cancer Cells Is Mediated by HIF-1α and Mutant p53 and Can Be Overcome by Induction of Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Christophe Deben

    2018-04-01

    Full Text Available The compound APR-246 (PRIMA-1MET is a known reactivator of (mutant p53 and inducer of oxidative stress which can sensitize cancer cells to platinum-based chemotherapeutics. However, the effect of a hypoxic tumor environment has been largely overlooked in this interaction. This study focusses on the role of hypoxia-inducible factor-1α (HIF-1α and the p53 tumor suppressor protein in hypoxia-induced cisplatin resistance in non-small cell lung cancer (NSCLC cells and the potential of APR-246 to overcome this resistance. We observed that hypoxia-induced cisplatin resistance only occurred in the p53 mutant NCI-H2228Q331* cell line, and not in the wild type A549 and mutant NCI-H1975R273H cell lines. Cisplatin reduced HIF-1α protein levels in NCI-H2228Q331* cells, leading to a shift in expression from HIF-1α-dependent to p53-dependent transcription targets under hypoxia. APR-246 was able to overcome hypoxia-induced cisplatin resistance in NCI-H2228Q331* cells in a synergistic manner without affecting mutant p53Q331* transcriptional activity, but significantly depleting total glutathione levels more efficiently under hypoxic conditions. Synergism was dependent on the presence of mutant p53Q331* and the induction of reactive oxygen species, with depletion of one or the other leading to loss of synergism. Our data further support the rationale of combining APR-246 with cisplatin in NSCLC, since their synergistic interaction is retained or enforced under hypoxic conditions in the presence of mutant p53.

  1. 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.

  2. Regulation of p53 tetramerization and nuclear export by ARC.

    Science.gov (United States)

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

    2007-12-26

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

  3. Predictive value of mutant p53 expression index obtained from nonenhanced computed tomography measurements for assessing invasiveness of ground-glass opacity nodules

    Directory of Open Access Journals (Sweden)

    Wang W

    2016-03-01

    Full Text Available Wei Wang,1 Jian Li,2 Ransheng Liu,1 Aixu Zhang,1 Zhiyong Yuan1 1Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center of Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, People’s Republic of China; 2Department of Radiology, Tianjin Hospital, Tianjin, People’s Republic of China Purpose: To predict p53 expression index (p53-EI based on measurements from computed tomography (CT for preoperatively assessing pathologies of nodular ground-glass opacities (nGGOs. Methods: Information of 176 cases with nGGOs on high-resolution CT that were pathologically confirmed adenocarcinoma was collected. Diameters, total volumes (TVs, maximum (MAX, average (AVG, and standard deviation (STD of CT attenuations within nGGOs were measured. p53-EI was evaluated through immunohistochemistry with Image-Pro Plus 6.0. A multiple linear stepwise regression model was established to calculate p53-EI prediction from CT measurements. Receiver-operating characteristic curve analysis was performed to compare the diagnostic performance of variables in differentiating preinvasive adenocarcinoma (PIA, minimally invasive adenocarcinoma (MIA, and invasive adenocarcinoma (IAC. Results: Diameters, TVs, MAX, AVG, and STD showed significant differences among PIAs, MIAs, and IACs (all P-values <0.001, with only MAX being incapable to differentiate MIAs from IACs (P=0.106. The mean p53-EIs of PIAs, MIAs, and IACs were 3.4±2.0, 7.2±1.9, and 9.8±2.7, with significant intergroup differences (all P-values <0.001. An equation was established by multiple linear regression as: p53-EI prediction =0.001* TVs +0.012* AVG +0.022* STD +9.345, through which p53-EI predictions were calculated to be 4.4%±1.0%, 6.8%±1.3%, and 8.5%±1.4% for PIAs, MIAs, and IACs (Kruskal–Wallis test P<0.001; Tamhane’s T2 test: PIA vs MIA P<0.001, MIA vs IAC P<0.001, respectively. Although not significant, p53-EI prediction

  4. The In Vivo DNA Binding Properties of Wild-Type and Mutant p53 Proteins in Mammary Cell Lines During the Course of Cell Cycle.

    Science.gov (United States)

    1996-08-01

    that my statement of work (SOW) for the current project omitted many of the tasks that had to be carried out in order to get the lab up and running...that we knew that we could stabilize wild-type p53 in ML-1 cells along with the possibility of being able to get an excellent elutriation profile with...nuclear protein extract was immunoprecipitated with PAb421 cross-linked to ProteinA -Sepharose beads and analysed by SDS-PAGE Western blot analysis with

  5. Transformation and radiosensitivity of human diploid skin fibroblasts transfected with SV40 T-antigen mutants defective in RB and P53 binding domains

    International Nuclear Information System (INIS)

    LingNah Su; Little, J.B.

    1992-01-01

    A series of human diploid fibroblast cell clones were developed by DNA transfection with either wild-type SV40 T-antigen (SV40T) or T-antigen mutants defective in its various functional domains. Cell clones expressing the wild-type SV40 T were significantly radioresistant as compared with clones transfected with the neo gene only (D o 192 ± 13 vs 127 ± 19). This radioresistance persisted in post-crisis, immortalized cell lines. A series of mutants with point or deletion mutations within each functionally active domain of SV40 T were also examined for their ability to alter radiosensitivity and induce morphological transformation. Cell clones transfected with T-antigen mutants defective in nuclear localization or origin binding showed increased radioresistance similar to clones transfected with wild-type T-antigen, and expressed morphological changes characteristic of SV40 T-transfected cells. (author)

  6. OTUD5 regulates p53 stability by deubiquitinating p53.

    Directory of Open Access Journals (Sweden)

    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.

  7. Suppression of p53 by Notch3 is mediated by Cyclin G1 and sustained by MDM2 and miR-221 axis in hepatocellular carcinoma

    Science.gov (United States)

    Baglioni, Michele; Fornari, Francesca; Giannone, Ferdinando; Ravaioli, Matteo; Cescon, Matteo; Chieco, Pasquale; Bolondi, Luigi; Gramantieri, Laura

    2014-01-01

    To successfully target Notch receptors as part of a multidrug anticancer strategy, it will be essential to fully characterize the factors that are modulated by Notch signaling. We recently reported that Notch3 silencing in HCC results in p53 up-regulation in vitro and, therefore, we focused on the mechanisms that associate Notch3 to p53 protein expression. We explored the regulation of p53 by Notch3 signalling in three HCC cell lines HepG2, SNU398 and Hep3B.We found that Notch3 regulates p53 at post-transcriptional level controlling both Cyclin G1 expression and the feed-forward circuit involving p53, miR-221 and MDM2. Moreover, our results were validated in human HCCs and in a rat model of HCC treated with Notch3 siRNAs. Our findings are becoming an exciting area for further in-depth research toward targeted inactivation of Notch3 receptor as a novel therapeutic approach for increasing the drug-sensitivity, and thereby improving the treatment outcome of patients affected by HCC. Indeed, we proved that Notch3 silencing strongly increases the effects of Nutilin-3. With regard to therapeutic implications, Notch3-specific drugs could represent a valuable strategy to limit Notch signaling in the context of hepatocellular carcinoma over-expressing this receptor. PMID:25431954

  8. 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.

  9. [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.

  10. PRIMA-1 and PRIMA-1Met (APR-246: From Mutant/Wild Type p53 Reactivation to Unexpected Mechanisms Underlying Their Potent Anti-Tumor Effect in Combinatorial Therapies

    Directory of Open Access Journals (Sweden)

    Anne Perdrix

    2017-12-01

    Full Text Available p53 protects cells from genetic assaults by triggering cell-cycle arrest and apoptosis. Inactivation of p53 pathway is found in the vast majority of human cancers often due to somatic missense mutations in TP53 or to an excessive degradation of the protein. Accordingly, reactivation of p53 appears as a quite promising pharmacological approach and, effectively, several attempts have been made in that sense. The most widely investigated compounds for this purpose are PRIMA-1 (p53 reactivation and induction of massive apoptosis and PRIMA-1Met (APR-246, that are at an advanced stage of development, with several clinical trials in progress. Based on publications referenced in PubMed since 2002, here we review the reported effects of these compounds on cancer cells, with a specific focus on their ability of p53 reactivation, an overview of their unexpected anti-cancer effects, and a presentation of the investigated drug combinations.

  11. 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)

  12. A nanobody modulates the p53 transcriptional program without perturbing its functional architecture

    Science.gov (United States)

    Bethuyne, Jonas; De Gieter, Steven; Zwaenepoel, Olivier; Garcia-Pino, Abel; Durinck, Kaat; Verhelle, Adriaan; Hassanzadeh-Ghassabeh, Gholamreza; Speleman, Frank; Loris, Remy; Gettemans, Jan

    2014-01-01

    The p53 transcription factor plays an important role in genome integrity. To perform this task, p53 regulates the transcription of genes promoting various cellular outcomes including cell cycle arrest, apoptosis or senescence. The precise regulation of this activity remains elusive as numerous mechanisms, e.g. posttranslational modifications of p53 and (non-)covalent p53 binding partners, influence the p53 transcriptional program. We developed a novel, non-invasive tool to manipulate endogenous p53. Nanobodies (Nb), raised against the DNA-binding domain of p53, allow us to distinctively target both wild type and mutant p53 with great specificity. Nb3 preferentially binds ‘structural’ mutant p53, i.e. R175H and R282W, while a second but distinct nanobody, Nb139, binds both mutant and wild type p53. The co-crystal structure of the p53 DNA-binding domain in complex with Nb139 (1.9 Å resolution) reveals that Nb139 binds opposite the DNA-binding surface. Furthermore, we demonstrate that Nb139 does not disturb the functional architecture of the p53 DNA-binding domain using conformation-specific p53 antibody immunoprecipitations, glutaraldehyde crosslinking assays and chromatin immunoprecipitation. Functionally, the binding of Nb139 to p53 allows us to perturb the transactivation of p53 target genes. We propose that reduced recruitment of transcriptional co-activators or modulation of selected post-transcriptional modifications account for these observations. PMID:25324313

  13. p53 downregulates the Fanconi anaemia DNA repair pathway.

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2008-08-01

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

  15. HEXIM1, a New Player in the p53 Pathway

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-04

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

  16. 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.

  17. 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

  18. 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.

  19. R248Q mutation--Beyond p53-DNA binding.

    Science.gov (United States)

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

    2015-12-01

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

  20. 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-...

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

    International Nuclear Information System (INIS)

    Min Fengling; Zhang Hong; Li Wenjian; Liu Bing; Zhou Qingming; Duan Xin; Gao Qingxiang

    2007-01-01

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

  2. 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.

  3. 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.

  4. The antagonism between MCT-1 and p53 affects the tumorigenic outcomes

    Directory of Open Access Journals (Sweden)

    Lin Tai-Du

    2010-12-01

    Full Text Available Abstract Background MCT-1 oncoprotein accelerates p53 protein degradation via a proteosome pathway. Synergistic promotion of the xenograft tumorigenicity has been demonstrated in circumstance of p53 loss alongside MCT-1 overexpression. However, the molecular regulation between MCT-1 and p53 in tumor development remains ambiguous. We speculate that MCT-1 may counteract p53 through the diverse mechanisms that determine the tumorigenic outcomes. Results MCT-1 has now identified as a novel target gene of p53 transcriptional regulation. MCT-1 promoter region contains the response elements reactive with wild-type p53 but not mutant p53. Functional p53 suppresses MCT-1 promoter activity and MCT-1 mRNA stability. In a negative feedback regulation, constitutively expressed MCT-1 decreases p53 promoter function and p53 mRNA stability. The apoptotic events are also significantly prevented by oncogenic MCT-1 in a p53-dependent or a p53-independent fashion, according to the genotoxic mechanism. Moreover, oncogenic MCT-1 promotes the tumorigenicity in mice xenografts of p53-null and p53-positive lung cancer cells. In support of the tumor growth are irrepressible by p53 reactivation in vivo, the inhibitors of p53 (MDM2, Pirh2, and Cop1 are constantly stimulated by MCT-1 oncoprotein. Conclusions The oppositions between MCT-1 and p53 are firstly confirmed at multistage processes that include transcription control, mRNA metabolism, and protein expression. MCT-1 oncogenicity can overcome p53 function that persistently advances the tumor development.

  5. 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.

  6. 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.

  7. 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).

  8. The p53-dependent radioadaptive response

    Science.gov (United States)

    Ohnishi, Takeo

    We already reported that conditioning exposures at low doses, or at low dose-rates, lowered radiation-induced p53-dependent apoptosis in cultured cells in vitro and in the spleens of mice in vivo. In this study, the aim was to characterize the p53-dependent radioadaptive response at the molecular level. We used wild-type (wt) p53 and mutated (m) p53 containing cells derived from the human lung cancer H1299 cell line, which is p53-null. Cellular radiation sensitivities were determined with a colony-forming assay. The accumulation of p53, Hdm2, and iNOS was analyzed with Western blotting. The quantification of chromosomal aberrations was estimated by scoring dicentrics per cell. In wtp53 cells, it was demonstrated that the lack of p53 accumulation was coupled with the activation of Hdm2 after low dose irradiation (0.02 Gy). Although NO radicals were only minimally induced in wtp53 cells irradiated with a challenging irradiation (6 Gy) alone, NO radicals were seen to increase about 2-4 fold after challenging irradiation following a priming irradiation (0.02 Gy). Under similar irradiation conditions with a priming and challenging irradiation in wtp53 cells, induction of radioresistance and a depression of chromosomal aberrations were observed only in the absence of Pifithrin-α (a p53 inhibitor), RITA or Nutlin-3 (p53-Hdm2 interaction inhibitors), aminoguanidine (an iNOS inhibitor) and c-PTIO (an NO radical scavenger). On the other hand, in p53 dysfunctional cells, a radioadaptive response was not observed in the presence or absence of those inhibitors. Moreover, radioresistance developed when wtp53 cells were treated with ISDN (an NO generating agent) alone. These findings suggest that NO radicals are an initiator of the radioadaptive response acting through the activation of Hdm2 and the depression of p53 accumulations.

  9. Expression of p53 in oligodendrogliomas

    NARCIS (Netherlands)

    J.M. Kros (Johan); J.J.C.J. Godschalk (J. J C J); K.K. Krishnadath (Kausilia); C.G. van Eden (C.)

    1993-01-01

    textabstractThe expression of the nuclear protein p53 in oligodendrogliomas was investigated by immunohistochemistry, using a monoclonal anti-p53 antibody (DO-7) on formalin-fixed, paraffin-embedded material in 84 histologically verified cases, and compared with the histopathological grade and

  10. Expression of p53 in oligodendrogliomas

    NARCIS (Netherlands)

    Kros, J. M.; Godschalk, J. J.; Krishnadath, K. K.; van Eden, C. G.

    1993-01-01

    The expression of the nuclear protein p53 in oligodendrogliomas was investigated by immunohistochemistry, using a monoclonal anti-p53 antibody (DO-7) on formalin-fixed, paraffin-embedded material in 84 histologically verified cases, and compared with the histopathological grade and survival.

  11. 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.

  12. Microbial Regulation of p53 Tumor Suppressor.

    Directory of Open Access Journals (Sweden)

    Alexander I Zaika

    2015-09-01

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

  13. 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.

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  16. 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.)

  17. 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...

  18. 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.

  19. 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.

  20. System-based strategies for p53 recovery.

    Science.gov (United States)

    Azam, Muhammad Rizwan; Fazal, Sahar; Ullah, Mukhtar; Bhatti, Aamer I

    2018-06-01

    The authors have proposed a systems theory-based novel drug design approach for the p53 pathway. The pathway is taken as a dynamic system represented by ordinary differential equations-based mathematical model. Using control engineering practices, the system analysis and subsequent controller design is performed for the re-activation of wild-type p53. p53 revival is discussed for both modes of operation, i.e. the sustained and oscillatory. To define the problem in control system paradigm, modification in the existing mathematical model is performed to incorporate the effect of Nutlin. Attractor point analysis is carried out to select the suitable domain of attraction. A two-loop negative feedback control strategy is devised to drag the system trajectories to the attractor point and to regulate cellular concentration of Nutlin, respectively. An integrated framework is constituted to incorporate the pharmacokinetic effects of Nutlin in the cancerous cells. Bifurcation analysis is also performed on the p53 model to see the conditions for p53 oscillation.

  1. 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

  2. P53 Gene Mutagenesis in Breast Cancer

    National Research Council Canada - National Science Library

    Sommer, Steve S

    2005-01-01

    .... The central hypothesis of this proposal is that variability in the patterns of p53 mutagensis in breast cancer reflects differences in exposures to different amounts and/or types of diverse environmental mutagens...

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  4. Stimulation of autophagy by the p53 target gene Sestrin2.

    Science.gov (United States)

    Maiuri, Maria Chiara; Malik, Shoaib Ahmad; Morselli, Eugenia; Kepp, Oliver; Criollo, Alfredo; Mouchel, Pierre-Luc; Carnuccio, Rosa; Kroemer, Guido

    2009-05-15

    The oncosuppressor protein p53 regulates autophagy in a dual fashion. The pool of cytoplasmic p53 protein represses autophagy in a transcription-independent fashion, while the pool of nuclear p53 stimulates autophagy through the transactivation of specific genes. Here we report the discovery that Sestrin2, a novel p53 target gene, is involved in the induction of autophagy. Depletion of Sestrin2 by RNA interference reduced the level of autophagy in a panel of p53-sufficient human cancer cell lines responding to distinct autophagy inducers. In quantitative terms, Sestrin2 depletion was as efficient in preventing autophagy induction as was the depletion of Dram, another p53 target gene. Knockout of either Sestrin2 or Dram reduced autophagy elicited by nutrient depletion, rapamycin, lithium or thapsigargin. Moreover, autophagy induction by nutrient depletion or pharmacological stimuli led to an increase in Sestrin2 expression levels in p53-proficient cells. In strict contrast, the depletion of Sestrin2 or Dram failed to affect autophagy in p53-deficient cells and did not modulate the inhibition of baseline autophagy by a cytoplasmic p53 mutant that was reintroduced into p53-deficient cells. We conclude that Sestrin2 acts as a positive regulator of autophagy in p53-proficient cells.

  5. Contribution of caspase-3 differs by p53 status in apoptosis induced by X-irradiation

    International Nuclear Information System (INIS)

    Kobayashi, Daisuke; Tokino, Takashi; Watanabe, Naoki

    2001-01-01

    We investigated the effect of p53 status on involvement of caspase-3 activation in cell death induced by X-irradiation, using rat embryonic fibroblasts (REFs) transduced with a temperature-sensitive mutant (mt) p53 gene. Cells with wild-type (wt) p53 showed greater resistance to X-irradiation than cells with mt p53. In cells with wt p53, X-irradiation-induced apoptosis was not inhibited by the caspase-3 inhibitor acetyl-L-aspartyl-L-methionyl-L-glutaminyl-L-aspartyl-aldehyde (Ac-DMQD-CHO) and caspase-3 activity was not elevated following X-irradiation, although induction of p53 and p21/WAF-1 protein was observed. In contrast, irradiated cells with mt p53 showed 89% inhibition of cell death with Ac-DMQD-CHO and 98% inhibition with the antioxidant N-acetyl-L-cysteine (NAC). In cells with mt p53, caspase-3 activity was increased approximately 5 times beyond baseline activity at 24 h after irradiation. This increase was almost completely inhibited by NAC. However, inhibition of caspase-3 by Ac-DMQD-CHO failed to decrease production of reactive oxygen species by cells with mt p53. Differential involvement of caspase-3 is a reason for differences in sensitivity to X-irradiation in cells with different p53 status. Caspase-3 activation appears to occur downstream from generation of reactive oxygen species occurring independently of wt p53 during X-irradiation-induced cell death. (author)

  6. Novel histone deacetylase inhibitor CG200745 induces clonogenic cell death by modulating acetylation of p53 in cancer cells.

    Science.gov (United States)

    Oh, Eun-Taex; Park, Moon-Taek; Choi, Bo-Hwa; Ro, Seonggu; Choi, Eun-Kyung; Jeong, Seong-Yun; Park, Heon Joo

    2012-04-01

    Histone deacetylase (HDAC) plays an important role in cancer onset and progression. Therefore, inhibition of HDAC offers potential as an effective cancer treatment regimen. CG200745, (E)-N(1)-(3-(dimethylamino)propyl)-N(8)-hydroxy-2-((naphthalene-1-loxy)methyl)oct-2-enediamide, is a novel HDAC inhibitor presently undergoing a phase I clinical trial. Enhancement of p53 acetylation by HDAC inhibitors induces cell cycle arrest, differentiation, and apoptosis in cancer cells. The purpose of the present study was to investigate the role of p53 acetylation in the cancer cell death caused by CG200745. CG200745-induced clonogenic cell death was 2-fold greater in RKO cells expressing wild-type p53 than in p53-deficient RC10.1 cells. CG200745 treatment was also cytotoxic to PC-3 human prostate cancer cells, which express wild-type p53. CG200745 increased acetylation of p53 lysine residues K320, K373, and K382. CG200745 induced the accumulation of p53, promoted p53-dependent transactivation, and enhanced the expression of MDM2 and p21(Waf1/Cip1) proteins, which are encoded by p53 target genes. An examination of CG200745 effects on p53 acetylation using cells transfected with various p53 mutants showed that cells expressing p53 K382R mutants were significantly resistant to CG200745-induced clonogenic cell death compared with wild-type p53 cells. Moreover, p53 transactivation in response to CG200745 was suppressed in all cells carrying mutant forms of p53, especially K382R. Taken together, these results suggest that acetylation of p53 at K382 plays an important role in CG200745-induced p53 transactivation and clonogenic cell death.

  7. 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.

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    Villiard Éric

    2007-09-01

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

  10. 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.

  11. 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

  12. Changes in p53 expression in mouse fibroblasts can modify motility and extracellular matrix organization.

    Science.gov (United States)

    Alexandrova, A; Ivanov, A; Chumakov, P; Kopnin, B; Vasiliev, J

    2000-11-23

    Effects of p53 expression on cell morphology and motility were studied using the derivatives of p53-null 10(1) mouse fibroblasts with tetracycline-regulated expression of exogenous human p53. Induction of p53 expression was accompanied by significant decrease in extracellular matrix (fibronectin) and reduction of matrix fibrils, diminution of the number and size of focal contacts, decrease of cell areas, establishment of more elongated cell shape and alterations of actin cytoskeleton (actin bundles became thinner, their number and size decreased). Expression of His175 and Gln22/ Ser23 p53 mutants caused no such effects. To study the influence of p53 expression on cell motility we used wound technique and videomicroscopy observation of single living cells. It was found that induction of p53 expression led to increase of lamellar activity of cell edge. However, in spite of enhanced lamellar activity p53-expressing cells migrated to shorter distance and filled the narrow wound in longer time as compared with their p53-null counterparts. Possible mechanisms of the influence of p53 expression on cell morphology and motility are discussed.

  13. Regulation of Metabolic Activity by p53

    Directory of Open Access Journals (Sweden)

    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.

  14. 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.

  15. 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

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

    International Nuclear Information System (INIS)

    Mukh-Syaifudin

    2006-01-01

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

  17. 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

  18. 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.

  19. 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

  20. 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

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

    Directory of Open Access Journals (Sweden)

    Herlia Nur Istindiah

    2015-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Karolyn J Forget

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

  3. 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

  4. Interaction of p53 with prolyl isomerases: Healthy and unhealthy relationships.

    Science.gov (United States)

    Mantovani, Fiamma; Zannini, Alessandro; Rustighi, Alessandra; Del Sal, Giannino

    2015-10-01

    The p53 protein family, comprising p53, p63 and p73, is primarily involved in preserving genome integrity and preventing tumor onset, and also affects a range of physiological processes. Signal-dependent modifications of its members and of other pathway components provide cells with a sophisticated code to transduce a variety of stress signaling into appropriate responses. TP53 mutations are highly frequent in cancer and lead to the expression of mutant p53 proteins that are endowed with oncogenic activities and sensitive to stress signaling. p53 family proteins have unique structural and functional plasticity, and here we discuss the relevance of prolyl-isomerization to actively shape these features. The anti-proliferative functions of the p53 family are carefully activated upon severe stress and this involves the interaction with prolyl-isomerases. In particular, stress-induced stabilization of p53, activation of its transcriptional control over arrest- and cell death-related target genes and of its mitochondrial apoptotic function, as well as certain p63 and p73 functions, all require phosphorylation of specific S/T-P motifs and their subsequent isomerization by the prolyl-isomerase Pin1. While these functions of p53 counteract tumorigenesis, under some circumstances their activation by prolyl-isomerases may have negative repercussions (e.g. tissue damage induced by anticancer therapies and ischemia-reperfusion, neurodegeneration). Moreover, elevated Pin1 levels in tumor cells may transduce deregulated phosphorylation signaling into activation of mutant p53 oncogenic functions. The complex repertoire of biological outcomes induced by p53 finds mechanistic explanations, at least in part, in the association between prolyl-isomerases and the p53 pathway. This article is part of a Special Issue entitled Proline-directed foldases: Cell signaling catalysts and drug targets. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. 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.

  6. A novel radiation-induced p53 mutation is not implicated in radiation resistance via a dominant-negative effect.

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    Yunguang Sun

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

  7. p53 is required for brain growth but is dispensable for resistance to nutrient restriction during Drosophila larval development.

    Science.gov (United States)

    Contreras, Esteban G; Sierralta, Jimena; Glavic, Alvaro

    2018-01-01

    Animal growth is influenced by the genetic background and the environmental circumstances. How genes promote growth and coordinate adaptation to nutrient availability is still an open question. p53 is a transcription factor that commands the cellular response to different types of stresses. In adult Drosophila melanogaster, p53 regulates the metabolic adaptation to nutrient restriction that supports fly viability. Furthermore, the larval brain is protected from nutrient restriction in a phenomenon called 'brain sparing'. Therefore, we hypothesised that p53 may regulate brain growth and show a protective role over brain development under nutrient restriction. Here, we studied the function of p53 during brain growth in normal conditions and in animals subjected to developmental nutrient restriction. We showed that p53 loss of function reduced animal growth and larval brain size. Endogenous p53 was expressed in larval neural stem cells, but its levels and activity were not affected by nutritional stress. Interestingly, p53 knockdown only in neural stem cells was sufficient to decrease larval brain growth. Finally, we showed that in p53 mutant larvae under nutrient restriction, the energy storage levels were not altered, and these larvae generated adults with brains of similar size than wild-type animals. Using genetic approaches, we demonstrate that p53 is required for proper growth of the larval brain. This developmental role of p53 does not have an impact on animal resistance to nutritional stress since brain growth in p53 mutants under nutrient restriction is similar to control animals.

  8. Interactions between the otitis media gene, Fbxo11, and p53 in the mouse embryonic lung.

    Science.gov (United States)

    Tateossian, Hilda; Morse, Susan; Simon, Michelle M; Dean, Charlotte H; Brown, Steve D M

    2015-12-01

    Otitis media with effusion (OME) is the most common cause of hearing loss in children, and tympanostomy (ear tube insertion) to alleviate the condition remains the commonest surgical intervention in children in the developed world. Chronic and recurrent forms of otitis media (OM) are known to have a very substantial genetic component; however, until recently, little was known of the underlying genes involved. The Jeff mouse mutant carries a mutation in the Fbxo11 gene, a member of the F-box family, and develops deafness due to a chronic proliferative OM. We previously reported that Fbxo11 is involved in the regulation of transforming growth factor beta (TGF-β) signalling by regulating the levels of phospho-Smad2 in the epithelial cells of palatal shelves, eyelids and airways of the lungs. It has been proposed that FBXO11 regulates the cell's response to TGF-β through the ubiquitination of CDT2. Additional substrates for FBXO11 have been identified, including p53. Here, we have studied both the genetic and biochemical interactions between FBXO11 and p53 in order to better understand the function of FBXO11 in epithelial development and its potential role in OM. In mice, we show that p53 (also known as Tp53) homozygous mutants and double heterozygous mutants (Jf/+ p53/+) exhibit similar epithelial developmental defects to Fbxo11 homozygotes. FBXO11 and p53 interact in the embryonic lung, and mutation in Fbxo11 prevents the interaction with p53. Both p53 and double mutants show raised levels of pSMAD2, recapitulating that seen in Fbxo11 homozygotes. Overall, our results support the conclusion that FBXO11 regulates the TGF-β pathway in the embryonic lung via cross-talk with p53. © 2015. Published by The Company of Biologists Ltd.

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

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    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Expression of Androgen Receptor Is Negatively Regulated By p53

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    Fatouma Alimirah

    2007-12-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2009-01-01

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

  13. 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

  14. Cell-Cycle-Specific Function of p53 in Fanconi Anemia Hematopoietic Stem and Progenitor Cell Proliferation

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    Xiaoli Li

    2018-02-01

    Full Text Available Summary: Overactive p53 has been proposed as an important pathophysiological factor for bone marrow failure syndromes, including Fanconi anemia (FA. Here, we report a p53-dependent effect on hematopoietic stem and progenitor cell (HSPC proliferation in mice deficient for the FA gene Fanca. Deletion of p53 in Fanca−/− mice leads to replicative exhaustion of the hematopoietic stem cell (HSC in transplant recipients. Using Fanca−/− HSCs expressing the separation-of-function mutant p53515C transgene, which selectively impairs the p53 function in apoptosis but keeps its cell-cycle checkpoint activities intact, we show that the p53 cell-cycle function is specifically required for the regulation of Fanca−/− HSC proliferation. Our results demonstrate that p53 plays a compensatory role in preventing FA HSCs from replicative exhaustion and suggest a cautious approach to manipulating p53 signaling as a therapeutic utility in FA. : In this article, Pang and colleagues demonstrate a p53-dependent HSPC proliferation regulation in mice deficient for the Fanca gene in the Fanconi anemia (FA pathway. They show that the p53 cell-cycle function is specifically required for the regulation of FA HSC proliferation. These results suggest that overactive p53 may represent a compensatory checkpoint mechanism for FA HSC proliferation. Keywords: p53, bone marrow failure, Fanconi anemia, hematopoietic stem and progenitor cells, apoptosis, cell cycle, proliferation

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

    International Nuclear Information System (INIS)

    Zo, Jae Ill; Zo, Kyung Ja; Park, Jong Ho; Kim, Mi Hee

    1998-01-01

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

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

    International Nuclear Information System (INIS)

    Milner, J.; Gamble, J.

    1985-01-01

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

  17. Pharmacological targeting of p53 through RITA is an effective antitumoral strategy for malignant pleural mesothelioma.

    Science.gov (United States)

    Di Marzo, Domenico; Forte, Iris Maria; Indovina, Paola; Di Gennaro, Elena; Rizzo, Valeria; Giorgi, Francesca; Mattioli, Eliseo; Iannuzzi, Carmelina Antonella; Budillon, Alfredo; Giordano, Antonio; Pentimalli, Francesca

    2014-01-01

    Malignant mesothelioma, a very aggressive tumor associated to asbestos exposure, is expected to increase in incidence, and unfortunately, no curative modality exists. Reactivation of p53 is a new attractive antitumoral strategy. p53 is rarely mutated in mesothelioma, but it is inactivated in most tumors by the lack of p14(ARF). Here, we evaluated the feasibility of this approach in pleural mesothelioma by testing RITA and nutlin-3, two molecules able to restore p53 function through a different mechanism, on a panel of mesothelioma cell lines representing the epithelioid (NCI-H28, NCI-H2452, IST-MES 2), biphasic (MSTO-211H), and sarcomatoid (NCI-H2052) histotypes compared with the normal mesothelial HMC-hTERT. RITA triggered robust caspase-dependent apoptosis specifically in epithelioid and biphasic mesothelioma cell lines, both through wild-type and mutant p53, concomitant to p21 downregulation. Conversely, nutlin-3 induced a p21-dependent growth arrest, rather than apoptosis, and was slightly toxic on HMC-hTERT.   Interestingly, we identified a previously undetected point mutation of p53 (p.Arg249Ser) in IST-MES 2, and showed that RITA is also able to reactivate this p53 mutant protein and its apoptotic function. RITA reduced tumor growth in a MSTO-211H-derived xenograft model of mesothelioma and synergized with cisplatin, which is the mainstay of treatment for this tumor. Our data indicate that reactivation of p53 and concomitant p21 downregulation effectively induce cell death in mesothelioma, a tumor characterized by a high intrinsic resistance to apoptosis. Altogether, our findings provide the preclinical framework supporting the use of p53-reactivating agents alone, or in combination regimens, to improve the outcome of patients with mesothelioma.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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

  20. Role of Peroxiredoxin I in Rectal Cancer and Related to p53 Status

    International Nuclear Information System (INIS)

    Chen, Miao-Fen; Lee, Kuan-Der; Yeh, Chung-Hung; Chen, Wen-Cheng; Huang, Wen-Shih; Chin, Chih-Chien; Lin, Paul- Yang; Wang, Jeng-Yi

    2010-01-01

    Background: Neoadjuvant chemoradiotherapy is widely accepted for the treatment of localized rectal cancer. Although peroxiredoxin I (PrxI) and p53 have been implicated in carcinogenesis and cancer treatment, the role of PrxI and its interaction with p53 in the prognosis and treatment response of rectal cancer remain relatively unstudied. Methods and Materials: In the present study, we examined the levels of PrxI and p53 in rectal cancer patients using membrane arrays and compared them with normal population samples. To demonstrate the biologic changes after manipulation of PrxI expression, we established stable transfectants of HCT-116 (wild-type p53) and HT-29 (mutant p53) cells with a PrxI silencing vector. The predictive capacities of PrxI and p53 were also assessed by relating the immunohistochemical staining of a retrospective series of rectal cancer cases to the clinical outcome. Results: The membrane array and immunochemical staining data showed that PrxI, but not p53, was significantly associated with the tumor burden. Our immunochemistry findings further indicated that PrxI positivity was linked to a poor response to neoadjuvant therapy and worse survival. In cellular and animal experiments, the inhibition of PrxI significantly decreased tumor growth and sensitized the tumor to irradiation, as indicated by a lower capacity to scavenge reactive oxygen species and more extensive DNA damage. The p53 status might have contributed to the difference between HCT-116 and HT-29 after knockdown of PrxI. Conclusion: According to our data, the level of PrxI combined with the p53 status is relevant to the prognosis and the treatment response. We suggested that PrxI might be a new biomarker for rectal cancer.

  1. 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.

  2. Caspase Activation and Aberrant Cell Growth in a p53+/+ Cell Line from a Li-Fraumeni Syndrome Family

    Directory of Open Access Journals (Sweden)

    Zaki A. Sherif

    2015-01-01

    Full Text Available Wild-type p53 is well known to induce cell cycle arrest and apoptosis to block aberrant cell growth. However, p53’s unique role in apoptosis and cell proliferation in Li-Fraumeni Syndrome (LFS has not been well elucidated. The aim of this study is to characterize the activity of wild-type p53 protein in LFS family dominated by a germline negative mutant p53. As expected, etoposide-treated wild-type p53-containing cell lines, LFS 2852 and control Jurkat, showed a greater rate of caspase- and annexin V-induced apoptotic cell death compared to the p53-mutant LFS 2673 cell line although mitochondrial and nuclear assays could not detect apoptosis in these organelles. The most intriguing part of the observation was the abnormal proliferation rate of the wild-type p53-containing cell line, which grew twice as fast as 2673 and Jurkat cells. This is important because apoptosis inducers acting through the mitochondrial death pathway are emerging as promising drugs against tumors where the role of p53 is not only to target gene regulation but also to block cell proliferation. This study casts a long shadow on the possible dysregulation of p53 mediators that enable cell proliferation. The deregulation of proliferation pathways represents an important anticancer therapeutic strategy for patients with the LFS phenotype.

  3. p53 specific (auto)immunity in mice

    NARCIS (Netherlands)

    Lauwen, Marjolein Monique

    2008-01-01

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

  4. Restriction of human herpesvirus 6B replication by p53

    DEFF Research Database (Denmark)

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

    2008-01-01

    Human herpesvirus 6B (HHV-6B) induces significant accumulation of p53 in both the nucleus and cytoplasm during infection. Activation of p53 by DNA damage is known to induce either growth arrest or apoptosis; nevertheless, HHV-6B-infected cells are arrested in their cell cycle independently of p53...

  5. 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

  6. 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.

  7. 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

  8. Design, Synthesis and In Vitro Activity of Anticancer Styrylquinolines. The p53 Independent Mechanism of Action

    Czech Academy of Sciences Publication Activity Database

    Mrozek-Wilczkiewicz, A.; Spaczynska, E.; Malarz, K.; Cieslik, W.; Rams-Baron, M.; Kryštof, Vladimír; Musiol, R.

    2015-01-01

    Roč. 10, č. 11 (2015), e0142678 E-ISSN 1932-6203 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : BIOLOGICAL-ACTIVITY SPECTRUM * MUTANT P53 * QUINOLINE DERIVATIVES Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.057, year: 2015

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

    Directory of Open Access Journals (Sweden)

    Hanqian Mao

    2016-09-01

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

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

    NARCIS (Netherlands)

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

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

  11. Screening of medicinal plant phytochemicals as natural antagonists of p53-MDM2 interaction to reactivate p53 functioning.

    Science.gov (United States)

    Riaz, Muhammad; Ashfaq, Usman A; Qasim, Muhammad; Yasmeen, Erum; Ul Qamar, Muhammad T; Anwar, Farooq

    2017-10-01

    In most types of cancer, overexpression of murine double minute 2 (MDM2) often leads to inactivation of p53. The crystal structure of MDM2, with a 109-residue amino-terminal domain, reveals that MDM2 has a core hydrophobic region to which p53 binds as an amphipathic α helix. The interface depends on the steric complementarity between MDM2 and the hydrophobic region of p53. Especially, on p53's triad, amino acids Phe19, Trp23 and Leu26 bind to the MDM2 core. Results from studies suggest that the structural motif of both p53 and MDM2 can be attributed to similarities in the amphipathic α helix. Thus, in the current investigation it is hypothesized that the similarity in the structural motif might be the cause of p53 inactivation by MDM2. Hence, molecular docking and phytochemical screening approaches are appraised to inhibit the hydrophobic cleft of MDM2 and to stop p53-MDM2 interaction, resulting in reactivation of p53 activity. For this purpose, a library of 2295 phytochemicals were screened against p53-MDM2 to find potential candidates. Of these, four phytochemicals including epigallocatechin gallate, alvaradoin M, alvaradoin E and nordihydroguaiaretic acid were found to be potential inhibitors of p53-MDM2 interaction. The screened phytochemicals, derived from natural extracts, may have negligible side effects and can be explored as potent antagonists of p53-MDM2 interactions, resulting in reactivation of the normal transcription of p53.

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

    NARCIS (Netherlands)

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

    1999-01-01

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

  13. 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

  14. Chemical Variations on the p53 Reactivation Theme

    Directory of Open Access Journals (Sweden)

    Carlos J. A. Ribeiro

    2016-05-01

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

  15. 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

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

    Science.gov (United States)

    2016-09-01

    in this progress report: p53 triple-negative breast cancer subtypes gene expression somatic cell genetics CRISPR / Cas 3. ACCOMPLISHMENTS Major...report, we described the creation of an isogenic p53 mutant TNBC cell line panel using CRISPR / Cas -mediated genome editing8 and the resultant...LOF null state. To validate that mutant p53 is directly responsible for this altered transcription, we will use the same CRISPR -mediated genome

  17. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  19. P53-dependent upregulation of neutral sphingomyelinase-2: role in doxorubicin-induced growth arrest.

    Science.gov (United States)

    Shamseddine, A A; Clarke, C J; Carroll, B; Airola, M V; Mohammed, S; Rella, A; Obeid, L M; Hannun, Y A

    2015-10-29

    Neutral sphingomyelinase-2 (nSMase2) is a ceramide-generating enzyme that has been implicated in growth arrest, apoptosis and exosome secretion. Although previous studies have reported transcriptional upregulation of nSMase2 in response to daunorubicin, through Sp1 and Sp3 transcription factors, the role of the DNA damage pathway in regulating nSMase2 remains unclear. In this study, we show that doxorubicin induces a dose-dependent induction of nSMase2 mRNA and protein with concomitant increases in nSMase activity and ceramide levels. Upregulation of nSMase2 was dependent on ATR, Chk1 and p53, thus placing it downstream of the DNA damage pathway. Moreover, overexpression of p53 was sufficient to transcriptionally induce nSMase2, without the need for DNA damage. DNA-binding mutants as well as acetylation mutants of p53 were unable to induce nSMase2, suggesting a role of nSMase2 in growth arrest. Moreover, knockdown of nSMase2 prevented doxorubicin-induced growth arrest. Finally, p53-induced nSMase2 upregulation appears to occur via a novel transcription start site upstream of exon 3. These results identify nSMase2 as a novel p53 target gene, regulated by the DNA damage pathway to induce cell growth arrest.

  20. Phenylbutyrate Sensitizes Human Glioblastoma Cells Lacking Wild-Type P53 Function to Ionizing Radiation

    International Nuclear Information System (INIS)

    Lopez, Carlos A.; Feng, Felix Y.; Herman, Joseph M.; Nyati, Mukesh K.; Lawrence, Theodore S.; Ljungman, Mats

    2007-01-01

    Purpose: Histone deacetylase (HDAC) inhibitors induce growth arrest, differentiation, and apoptosis in cancer cells. Phenylbutyrate (PB) is a HDAC inhibitor used clinically for treatment of urea cycle disorders. Because of its low cytotoxicity, cerebrospinal fluid penetration, and high oral bioavailability, we investigated PB as a potential radiation sensitizer in human glioblastoma cell lines. Methods and Materials: Four glioblastoma cell lines were selected for this study. Phenylbutyrate was used at a concentration of 2 mM, which is achievable in humans. Western blots were used to assess levels of acetylated histone H3 in tumor cells after treatment with PB. Flow cytometry was used for cell cycle analysis. Clonogenic assays were performed to assess the effect of PB on radiation sensitivity. We used shRNA against p53 to study the role of p53 in radiosensitization. Results: Treatment with PB alone resulted in hyperacetylation of histones, confirmed by Western blot analysis. The PB alone resulted in cytostatic effects in three cell lines. There was no evidence of G 1 arrest, increase in sub-G 1 fraction or p21 protein induction. Clonogenic assays showed radiosensitization in two lines harboring p53 mutations, with enhancement ratios (± SE) of 1.5 (± 0.2) and 1.3 (± 0.1), respectively. There was no radiopotentiating effect in two cell lines with wild-type p53, but knockdown of wild-type p53 resulted in radiosensitization by PB. Conclusions: Phenylbutyrate can produce p21-independent cytostasis, and enhances radiation sensitivity in p53 mutant human glioblastoma cells in vitro. This suggests the potential application of combined PB and radiotherapy in glioblastoma harboring mutant p53

  1. p53/PUMA expression in human pulmonary fibroblasts mediates cell activation and migration in silicosis.

    Science.gov (United States)

    Wang, Wei; Liu, Haijun; Dai, Xiaoniu; Fang, Shencun; Wang, Xingang; Zhang, Yingming; Yao, Honghong; Zhang, Xilong; Chao, Jie

    2015-11-18

    Phagocytosis of SiO2 into the lung causes an inflammatory cascade that results in fibroblast proliferation and migration, followed by fibrosis. Clinical evidence has indicated that the activation of alveolar macrophages by SiO2 produces rapid and sustained inflammation characterized by the generation of monocyte chemotactic protein 1, which, in turn, induces fibrosis. However, the details of events downstream of monocyte chemotactic protein 1 activity in pulmonary fibroblasts remain unclear. Here, to elucidate the role of p53 in fibrosis induced by silica, both the upstream molecular mechanisms and the functional effects on cell proliferation and migration were investigated. Experiments using primary cultured adult human pulmonary fibroblasts led to the following results: 1) SiO2 treatment resulted in a rapid and sustained increase in p53 and PUMA protein levels; 2) the MAPK and PI3K pathways were involved in the SiO2-induced alteration of p53 and PUMA expression; and 3) RNA interference targeting p53 and PUMA prevented the SiO2-induced increases in fibroblast activation and migration. Our study elucidated a link between SiO2-induced p53/PUMA expression in fibroblasts and cell migration, thereby providing novel insight into the potential use of p53/PUMA in the development of novel therapeutic strategies for silicosis treatment.

  2. The role of the expression of bcl-2, p53 gene in tamoxifen-induced apoptosis of breast cancer cells and its relationship with hormone receptor status

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Woo Chul; Ham, Yong Ho [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1998-01-01

    To investigate the relationship of bcl-2, p53, ER and tamoxifen-induced apoptosis of breast cancer cells, MCF-7 (ER+/bcl-2+/p53-) and MB MDA 468 (ER-/bcl-2-/p53+) cell line were cultured in estrogen-free condition. E2(10`-`9M) and tamoxifen (10`-`5M) were added to the media. The changes of bcl-2 and mutant p53 protein were checked by Western blot and apoptosis were measured by flowcytometry. In MCF-7 cells, we found that treatment with tamoxifen resulted in a decrease in bcl-2 protein level, but produced no change in mutant p53. In MB MDA 468 cell however, there were no changes of bcl-2 and mutant p53 protein level when E2 or tamoxifen were added. Apoptotic cells increased with time-dependent pattern when tamoxifen was added to MCF-7 cells. According to these result, ER+/blc-2+/mutant p53- cells, when treated with tamoxifen, were converted into bcl-2/mutant p53- cells which were more prone to apoptosis than bcl-2-/mutant p53+ cells. The paradoxical correlation of bcl-2 and ER which had been observed in clinical studies might be explained with this results and bcl-2 protein seems to be one of important factors that can predict the effect of hormone therapy. (author). 26 refs., 5 figs

  3. The role of the expression of bcl-2, p53 gene in tamoxifen-induced apoptosis of breast cancer cells and its relationship with hormone receptor status

    International Nuclear Information System (INIS)

    Noh, Woo Chul; Ham, Yong Ho

    1998-01-01

    To investigate the relationship of bcl-2, p53, ER and tamoxifen-induced apoptosis of breast cancer cells, MCF-7 (ER+/bcl-2+/p53-) and MB MDA 468 (ER-/bcl-2-/p53+) cell line were cultured in estrogen-free condition. E2(10'-'9M) and tamoxifen (10'-'5M) were added to the media. The changes of bcl-2 and mutant p53 protein were checked by Western blot and apoptosis were measured by flowcytometry. In MCF-7 cells, we found that treatment with tamoxifen resulted in a decrease in bcl-2 protein level, but produced no change in mutant p53. In MB MDA 468 cell however, there were no changes of bcl-2 and mutant p53 protein level when E2 or tamoxifen were added. Apoptotic cells increased with time-dependent pattern when tamoxifen was added to MCF-7 cells. According to these result, ER+/blc-2+/mutant p53- cells, when treated with tamoxifen, were converted into bcl-2/mutant p53- cells which were more prone to apoptosis than bcl-2-/mutant p53+ cells. The paradoxical correlation of bcl-2 and ER which had been observed in clinical studies might be explained with this results and bcl-2 protein seems to be one of important factors that can predict the effect of hormone therapy. (author). 26 refs., 5 figs

  4. 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.

  5. Combining Oncolytic Virotherapy with p53 Tumor Suppressor Gene Therapy

    Directory of Open Access Journals (Sweden)

    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.

  6. Targeting the p53 Pathway in Ewing Sarcoma

    Science.gov (United States)

    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

  7. Interplay between PTB and miR-1285 at the p53 3'UTR modulates the levels of p53 and its isoform Δ40p53α.

    Science.gov (United States)

    Katoch, Aanchal; George, Biju; Iyyappan, Amrutha; Khan, Debjit; Das, Saumitra

    2017-09-29

    p53 and its translational isoform Δ40p53 are involved in many important cellular functions like cell cycle, cell proliferation, differentiation and metabolism. Expression of both the isoforms can be regulated at different steps. In this study, we explored the role of 3'UTR in regulating the expression of these two translational isoforms. We report that the trans acting factor, Polypyrimidine Tract Binding protein (PTB), also interacts specifically with 3'UTR of p53 mRNA and positively regulates expression of p53 isoforms. Our results suggest that there is interplay between miRNAs and PTB at the 3'UTR under normal and stress conditions like DNA damage. Interestingly, PTB showed some overlapping binding regions in the p53 3'UTR with miR-1285. In fact, knockdown of miR-1285 as well as expression of p53 3'UTR with mutated miR-1285 binding sites resulted in enhanced association of PTB with the 3'UTR, which provides mechanistic insights of this interplay. Taken together, the results provide a plausible molecular basis of how the interplay between miRNAs and the PTB protein at the 3'UTR can play pivotal role in fine tuning the expression of the two p53 isoforms. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  8. 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.

  9. Combination of heavy-ion radiotherapy and p53-gene therapy by radio- and hypoxia-sensitizing promoter for glioma

    International Nuclear Information System (INIS)

    Oga, Masaru; Koshikawa, Nobuko; Takenaga, Keizo; Iwadate, Yasuo; Nojima, Kumie

    2006-01-01

    In this study we have started to investigate the anti-tumor effect of the combination of heavy-ion radiotherapy, inducing p53-independent apoptosis, and p53-gene therapy, inducing p53-dependent apoptosis for glioma. To enhance the p53-dependent apoptosis, we chose the strategy to utilize the heavy-ion irradiation itself as a ''trigger'' by using radio-sensitizing E 9ns-2 /cytomegalovirus (CMV) chimeric promoter (Scott et al: 2003) in p53-gene therapy. Our study in the first year, however, suggested the uselessness of E 9ns-2 /CMV chimeric promoter. Then we applied E 9ns-2 /Epo5/CMV-radio and hypoxia-sensitizing chimeric promoter to amplify p53 gene exopression. P53 gene with E 9ns2 /Epo5/CMV chimeric promoter was transfected in p53-mutant U373MG human glioma cell-line and the transfected-cell bulk was irradiated at dose of 1 Gy of high linear energy transfer (LET)-carbon ion beam or low-LET X-ray under various hypoxic conditions. The result suggested the possible role of 1 Gy of high LET-carbon ion beam as a ''useful trigger'' to enhance a selective anti-tumor effect toward glioma under hypoxic condition through amplification of p53 gene expression. (author)

  10. 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.

  11. 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.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  14. 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

  15. 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...

  16. The nucleolus directly regulates p53 export and degradation.

    Science.gov (United States)

    Boyd, Mark T; Vlatkovic, Nikolina; Rubbi, Carlos P

    2011-09-05

    The correlation between stress-induced nucleolar disruption and abrogation of p53 degradation is evident after a wide variety of cellular stresses. This link may be caused by steps in p53 regulation occurring in nucleoli, as suggested by some biochemical evidence. Alternatively, nucleolar disruption also causes redistribution of nucleolar proteins, potentially altering their interactions with p53 and/or MDM2. This raises the fundamental question of whether the nucleolus controls p53 directly, i.e., as a site where p53 regulatory processes occur, or indirectly, i.e., by determining the cellular localization of p53/MDM2-interacting factors. In this work, transport experiments based on heterokaryons, photobleaching, and micronucleation demonstrate that p53 regulatory events are directly regulated by nucleoli and are dependent on intact nucleolar structure and function. Subcellular fractionation and nucleolar isolation revealed a distribution of ubiquitylated p53 that supports these findings. In addition, our results indicate that p53 is exported by two pathways: one stress sensitive and one stress insensitive, the latter being regulated by activities present in the nucleolus.

  17. The Transcriptional Landscape of p53 Signalling Pathway

    Directory of Open Access Journals (Sweden)

    Chizu Tanikawa

    2017-06-01

    Full Text Available Although recent cancer genomics studies have identified a large number of genes that were mutated in human cancers, p53 remains as the most frequently mutated gene. To further elucidate the p53-signalling network, we performed transcriptome analysis on 24 tissues in p53+/+ or p53−/− mice after whole-body X-ray irradiation. Here we found transactivation of a total of 3551 genes in one or more of the 24 tissues only in p53+/+ mice, while 2576 genes were downregulated. p53 mRNA expression level in each tissue was significantly associated with the number of genes upregulated by irradiation. Annotation using TCGA (The Cancer Genome Atlas database revealed that p53 negatively regulated mRNA expression of several cancer therapeutic targets or pathways such as BTK, SYK, and CTLA4 in breast cancer tissues. In addition, stomach exhibited the induction of Krt6, Krt16, and Krt17 as well as loricrin, an epidermal differentiation marker, after the X-ray irradiation only in p53+/+ mice, implying a mechanism to protect damaged tissues by rapid induction of differentiation. Our comprehensive transcriptome analysis elucidated tissue specific roles of p53 and its signalling networks in DNA-damage response that will enhance our understanding of cancer biology.

  18. Increased sensitivity of p53-deficient cells to anticancer agents due to loss of Pms2

    Science.gov (United States)

    Fedier, A; Ruefenacht, U B; Schwarz, V A; Haller, U; Fink, D

    2002-01-01

    A large fraction of human tumours carries mutations in the p53 gene. p53 plays a central role in controlling cell cycle checkpoint regulation, DNA repair, transcription, and apoptosis upon genotoxic stress. Lack of p53 function impairs these cellular processes, and this may be the basis of resistance to chemotherapeutic regimens. By virtue of the involvement of DNA mismatch repair in modulating cytotoxic pathways in response to DNA damaging agents, we investigated the effects of loss of Pms2 on the sensitivity to a panel of widely used anticancer agents in E1A/Ha-Ras-transformed p53-null mouse fibroblasts either proficient or deficient in Pms2. We report that lack of the Pms2 gene is associated with an increased sensitivity, ranging from 2–6-fold, to some types of anticancer agents including the topoisomerase II poisons doxorubicin, etoposide and mitoxantrone, the platinum compounds cisplatin and oxaliplatin, the taxanes docetaxel and paclitaxel, and the antimetabolite gemcitabine. In contrast, no change in sensitivity was found after treatment with 5-fluorouracil. Cell cycle analysis revealed that both, Pms2-deficient and -proficient cells, retain the ability to arrest at the G2/M upon cisplatin treatment. The data indicate that the concomitant loss of Pms2 function chemosensitises p53-deficient cells to some types of anticancer agents, that Pms2 positively modulates cell survival by mechanisms independent of p53, and that increased cytotoxicity is paralleled by increased apoptosis. Tumour-targeted functional inhibition of Pms2 may be a valuable strategy for increasing the efficacy of anticancer agents in the treatment of p53-mutant cancers. British Journal of Cancer (2002) 87, 1027–1033. doi:10.1038/sj.bjc.6600599 www.bjcancer.com © 2002 Cancer Research UK PMID:12434296

  19. G2-block after irradiation of cells with different p53 status

    International Nuclear Information System (INIS)

    Zoelzer, Friedo; Jagetia, Ganesh; Streffer, Christian

    2014-01-01

    Although it is clear that functional p53 is not required for radiation-induced G 2 block, certain experimental findings suggest a role for p53 in this context. For instance, as we also confirm here, the maximum accumulation in the G 2 compartment after X-ray exposure occurs much later in p53 mutants than in wild types. It remains to be seen, however, whether this difference is due to a longer block in the G 2 phase itself. We observed the movement of BrdU-labeled cells through G 2 and M into G 1 . From an analysis of the fraction of labeled cells that entered the second posttreatment cell cycle, we were able to determine the absolute duration of the G 2 and M phases in unirradiated and irradiated cells. Our experiments with four cell lines, two melanomas and two squamous carcinomas, showed that the radiation-induced delay of transition through the G 2 and M phases did not correlate with p53 status. We conclude that looking at the accumulation of cells in the G 2 compartment alone is misleading when differences in the G 2 block are investigated and that the G 2 block itself is indeed independent of functional p53. (orig.) [de

  20. 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.

  1. Cancerous hyper-mutagenesis in p53 genes is possibly associated with transcriptional bypass of DNA lesions

    International Nuclear Information System (INIS)

    Rodin, S.N.; Rodin, A.S.; Juhasz, A.; Holmquist, G.P.

    2002-01-01

    The database of tumor-associated p53 base substitutions includes about 5% of tumors with two or more base substitutions. These multiplet base substitutions in one tumor are evidence for hyper-mutagenesis. Our retrospective analysis of this database indicates that most multiplets arise from a single transient hyper-mutagenic event in one cell that subsequently proliferated into a clonal tumor. The hyper-mutagenesis, 1.8x10 -4 substitutions per base pair, is detected as multiple mutations in p53 genes of tumors. It requires one strongly tumorigenic p53 substitution, usually missense, called the driver mutation. The occurrence frequencies of ancillary base substitutions, those that hitch-hike along with the driver mutation, are independent of their amino acid coding properties. In this respect, they act like neutral mutations. In support of this neutrality, we find that the frequency distribution of hitch-hiking CpG transitions along the p53 exons, their mutational spectrum, approximates the spontaneous pre-selection mutational spectrum of most human tissues and is correlated with the mutational spectrum of p53 pseudogenes in mammalian germ cells. The driver substitutions of multiplets predominantly originate along the transcribed strand while the ancillary substitutions tend to originate along the non-transcribed strand. This data is consistent with a model of time-dependent mutagenesis in non-dividing stem cells for generating multiple strand-asymmetric p53 mutations in tumors. By transcriptional bypass of DNA lesions with concomitant misincorporation, transcriptional mutagenesis generates a transient mutant p53 mRNA. The associated mutant p53 protein could allow the host cell a growth advantage, release from G 1 -arrest. Then, during subsequent DNA replication and misreading of the same lesion, the damaged base along the transcribed DNA strand would serve as the origin of the p53 base substitution that drives the hyper-mutagenic event leading to tumors with

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

    Science.gov (United States)

    Michaelis, M; Rothweiler, F; Agha, B; Barth, S; Voges, Y; Löschmann, N; von Deimling, A; Breitling, R; Doerr, H Wilhelm; Rödel, F; Speidel, D; Cinatl, J

    2012-04-05

    Adaptation of wild-type p53 expressing UKF-NB-3 cancer cells to the murine double minute 2 inhibitor nutlin-3 causes de novo p53 mutations at high frequency (13/20) and multi-drug resistance. Here, we show that the same cells respond very differently when adapted to RITA, a drug that, like nutlin-3, also disrupts the p53/Mdm2 interaction. All of the 11 UKF-NB-3 sub-lines adapted to RITA that we established retained functional wild-type p53 although RITA induced a substantial p53 response. Moreover, all RITA-adapted cell lines remained sensitive to nutlin-3, whereas only five out of 10 nutlin-3-adapted cell lines retained their sensitivity to RITA. In addition, repeated adaptation of the RITA-adapted sub-line UKF-NB-3(r)RITA(10 μM) to nutlin-3 resulted in p53 mutations. The RITA-adapted UKF-NB-3 sub-lines displayed no or less pronounced resistance to vincristine, cisplatin, and irradiation than nutlin-3-adapted UKF-NB-3 sub-lines. Furthermore, adaptation to RITA was associated with fewer changes at the expression level of antiapoptotic factors than observed with adaptation to nutlin-3. Transcriptomic analyses indicated the RITA-adapted sub-lines to be more similar at the gene expression level to the parental UKF-NB-3 cells than nutlin-3-adapted UKF-NB-3 sub-lines, which correlates with the observed chemotherapy and irradiation sensitivity phenotypes. In conclusion, RITA-adapted cells retain functional p53, remain sensitive to nutlin-3, and display a less pronounced resistance phenotype than nutlin-3-adapted cells.

  3. 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

  4. 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).

  5. Chronology of p53 protein accumulation in gastric carcinogenesis

    NARCIS (Netherlands)

    Craanen, M. E.; Blok, P.; Dekker, W.; Offerhaus, G. J.; Tytgat, G. N.

    1995-01-01

    p53 Protein accumulation in early gastric carcinoma was studied in relation to the histological type (Lauren classification) and the type of growth pattern, including the chronology of p53 protein accumulation during carcinogenesis. Forty five, paraffin embedded gastrectomy specimens from early

  6. Lunatic Fringe and p53 Cooperatively Suppress Mesenchymal Stem-Like Breast Cancer

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Chung

    2017-11-01

    Full Text Available Claudin-low breast cancer (CLBC is a poor prognosis molecular subtype showing stemness and mesenchymal features. We previously discovered that deletion of a Notch signaling modulator, Lunatic Fringe (Lfng, in the mouse mammary gland induced a subset of tumors resembling CLBC. Here we report that deletion of one copy of p53 on this background not only accelerated mammary tumor development but also led to a complete penetrance of the mesenchymal stem-like phenotype. All mammary tumors examined in the Lfng/p53 compound mutant mice displayed a mesenchymal/spindloid pathology. These tumors showed high level expressions of epithelial-to-mesenchymal transition (EMT markers including Vimentin, Twist, and PDGFRα, a gene known to be enriched in CLBC. Prior to tumor onset, Lfng/p53 mutant mammary glands exhibited increased levels of Vimentin and E-cadherin, but decreased expressions of cytokeratin 14 and cytokeratin 8, accompanied by elevated basal cell proliferation and an expanded mammary stem cell-enriched population. Lfng/p53 mutant glands displayed increased accumulation of Notch3 intracellular fragment, up-regulation of Hes5 and down-regulation of Hes1. Analysis in human breast cancer datasets found the lowest HES1 and second lowest LFNG expressions in CLBC among molecular subtypes, and low level of LFNG is associated with poor survival. Immunostaining of human breast cancer tissue array found correlation between survival and LFNG immunoreactivity. Finally, patients carrying TP53 mutations express lower LFNG than patients with wild type TP53. Taken together, these data revealed genetic interaction between Lfng and p53 in mammary tumorigenesis, established a new mouse model resembling CLBC, and may suggest targeting strategy for this disease.

  7. Heterozygous loss of TSC2 alters p53 signaling and human stem cell reprogramming.

    Science.gov (United States)

    Armstrong, Laura C; Westlake, Grant; Snow, John P; Cawthon, Bryan; Armour, Eric; Bowman, Aaron B; Ess, Kevin C

    2017-12-01

    Tuberous sclerosis complex (TSC) is a pediatric disorder of dysregulated growth and differentiation caused by loss of function mutations in either the TSC1 or TSC2 genes, which regulate mTOR kinase activity. To study aberrations of early development in TSC, we generated induced pluripotent stem cells using dermal fibroblasts obtained from patients with TSC. During validation, we found that stem cells generated from TSC patients had a very high rate of integration of the reprogramming plasmid containing a shRNA against TP53. We also found that loss of one allele of TSC2 in human fibroblasts is sufficient to increase p53 levels and impair stem cell reprogramming. Increased p53 was also observed in TSC2 heterozygous and homozygous mutant human stem cells, suggesting that the interactions between TSC2 and p53 are consistent across cell types and gene dosage. These results support important contributions of TSC2 heterozygous and homozygous mutant cells to the pathogenesis of TSC and the important role of p53 during reprogramming. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. 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)

  9. S-phase checkpoint elements of the E2F-1 family increase radiosensitivity in fibrosarcoma cells lacking p53

    International Nuclear Information System (INIS)

    Bodis, Stephan; Pruschy, Martin; Wirbelauer, Christiane; Glanzmann, Christoph; Krek, Wilhelm

    1997-01-01

    Purpose: Correct advance of cells through the S-phase of the mammalian cell cycle depends on the timely controlled activity of the E2F-1 transcription factor by cyclin A-cdk2. We are studying the reproductive integrity and radiosensitation of isogenic mouse fibrosarcoma cells, differing only in their p53 status, after expression of E2F-1 wildtype (wt) and specific E2F-1 mutants (mt) lacking the cyclin-A-binding domain. In this tumor model system only p53 wild-type expressing tumor cells are sensitive to ionizing radiation in vitro and in vivo. Material and Methods: Either wild-type p53 or genetically engineered p53 'null' mouse embryo fibroblasts were transfected with the oncogenes E1A and ras. These otherwise isogenic fibrosarcoma cells, with a malignant phenotype and tumorigenic in nude mice, were transfected with retroviruses containing either E2F-1 wild-type or specific E2F-1 mutants lacking the cyclin-A binding domain. Reproductive integrity after E2F-1 transfection with or without ionizing radiation (RT) was tested using the clonogenic assay. Tumor cell morphology of treated cells is analyzed for cell death mechanism. Results: E2F-1 wild-type expression in fibrosarcoma cells induced a clear p53 dependent cell death. While clonogenic survival of p53 'null' tumor cells was only slightly reduced with the expression of E2F-1 wild type (survival fraction of 0.5), the clonogenic survival of p53 wild-type fibrosarcoma tumor cells was reduced by at least one logarithm (survival fraction of 0.05). However, expression of the specific E2F-1 mutant lacking the cyclin-A binding domain reduced clonogenic survival in both the p53 'null' and the p53 wild-type fibrosarcoma cells by at least 2 logarithms (survival fraction 0.01 for p53 'null' and 0.002 for p53 wild-type). The mean values of the survival fractions after 2 and 5 Gy radiation alone in p53 'null' fibrosarcoma cells (SF 2 and SF 5) were SF 2 0.7, SF 5 = 0.15, respectively. The combination of ionizing RT in the p53

  10. 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.

  11. 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.

  12. Combination of Heavy-ion radiotherapy and p53-gene therapy by radio-sensitizing promoter for glioma

    International Nuclear Information System (INIS)

    Oga, Masaru; Koshikawa, Nobuko; Takenaga, Keizo; Iwadate, Yasuo; Nojima, Kumie

    2005-01-01

    In this study we have investigated the anti-tumor effect of the combination of heavy-ion radiotherapy, inducing p53-independent apoptosis, and p53-gene therapy, inducing p53-dependent apoptosis for glioma. To enhance the p53-dependent apoptosis, we chose the strategy to utilize the heavy-ion irradiation itself as a ''trigger'' by using radio-sensitizing promoter-E9ns-2/CMV chimeric promoter (Scott et al:2003) in p53-gene therapy. First, EGFP reporter gene with E9ns-2/CMV chimeric promoter was transfected in C6 rat glioma cell-line and the transfected-cell bulk was irradiated at dose of 3, 5, 10 Gy respectively with charged carbon particle (290 MeV/nucleon). The light upregulation of EGFP was observed in 24 hours after 5 Gy irradiation. On the basis of this result, p53 gene with E9ns-2/CMV chimeric promoter was transfected in p53-mutant U373MG human glioma cell-line and the transfected-cell bulk was irradiated at dose of 5 Gy. There was, however, no obvious p53-upregulation at any time-point, so far. Further investigation is needed to clarify the appropriate experimental system. (author)

  13. Expression of Egr1 and p53 in human carotid plaques and apoptosis induced by 7-oxysterol or p53.

    Science.gov (United States)

    Miah, Sayem; Zadeh, Shahram Nour Mohammad; Yuan, Xi-Ming; Li, Wei

    2013-07-01

    Egr-1 and p53 are involved in pathology of both atherosclerosis and cancer. However, it is unknown whether p53 and Egr1 are interactively involved in apoptosis in atherosclerosis. We found that in human carotid plaques, the expression of p53 was inversely correlated with Egr1. In U937 cells, 7β-hydroxycholesterol and 7-ketocholesterol induced production of reactive oxygen species (ROS), transient up-regulation of Egr1 followed by late induction of p53 and apoptosis. Cells with nuclear fragmentation induced by 7-oxysterol or p53 showed increased levels of p53, but decreased levels of Egr1. In conclusion, ROS induced by 7-oxysterols may function as an early initiator of Egr1 expression. The late induced p53 by 7-oxysterols contributes to apoptotic cell death and is linked to the reduction of Egr1 levels, which resembles the differential expression of p53 and Egr1 in human atheroma progression. Copyright © 2012 Elsevier GmbH. All rights reserved.

  14. 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

  15. Cisplatinum and Taxol Induce Different Patterns of p53 Phosphorylation

    Directory of Open Access Journals (Sweden)

    Giovanna Damia

    2001-01-01

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

  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. 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. P53 expression in prostatic cancer: an immunohistochemical study

    International Nuclear Information System (INIS)

    Al-Nuaimy, W.M.; Al-Allaf, L.I.; Alnaimi, H.A.

    2011-01-01

    Prostate cancer is the most common malignancy in men and second leading cause of cancer death in the Western world. P53 alterations are the most frequent genetic changes in human cancers. Mutation of the p53 gene has been implicated in the development of >50% of all human cancer. The current study aims at evaluating the immuno-histochemical expression of p53 protein in patients with cancer of prostate, as prognostic parameter in correlation with other parameters including PSA receptors, and to correlate the results with those of other studies. (authors).

  19. Robustness of the p53 network and biological hackers.

    Science.gov (United States)

    Dartnell, Lewis; Simeonidis, Evangelos; Hubank, Michael; Tsoka, Sophia; Bogle, I David L; Papageorgiou, Lazaros G

    2005-06-06

    The p53 protein interaction network is crucial in regulating the metazoan cell cycle and apoptosis. Here, the robustness of the p53 network is studied by analyzing its degeneration under two modes of attack. Linear Programming is used to calculate average path lengths among proteins and the network diameter as measures of functionality. The p53 network is found to be robust to random loss of nodes, but vulnerable to a targeted attack against its hubs, as a result of its architecture. The significance of the results is considered with respect to mutational knockouts of proteins and the directed attacks mounted by tumour inducing viruses.

  20. 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.)

  1. BAK overexpression mediates p53-independent apoptosis inducing effects on human gastric cancer cells

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2004-07-01

    Full Text Available Abstract Background BAK (Bcl-2 homologous antagonist/killer is a novel pro-apoptotic gene of the Bcl-2 family. It has been reported that gastric tumors have reduced BAK levels when compared with the normal mucosa. Moreover, mutations of the BAK gene have been identified in human gastrointestinal cancers, suggesting that a perturbation of BAK-mediated apoptosis may contribute to the pathogenesis of gastric cancer. In this study, we explored the therapeutic effects of gene transfer mediated elevations in BAK expression on human gastric cancer cells in vitro. Methods Eukaryotic expression vector for the BAK gene was constructed and transferred into gastric cancer cell lines, MKN-45 (wild-type p53 and MKN-28 (mutant-type p53. RT-PCR and Western Blotting detected cellular BAK gene expression. Cell growth activities were detected by MTT colorimetry and flow cytometry, while apoptosis was assayed by electronic microscopy and TUNEL. Western Blotting and colorimetry investigated cellular caspase-3 activities. Results BAK gene transfer could result in significant BAK overexpression, decreased in vitro growth, cell cycle G0/G1 arrest, and induced apoptosis in gastric cancer cells. In transferred cells, inactive caspase-3 precursor was cleaved into the active subunits p20 and p17, during BAK overexpression-induced apoptosis. In addition, this process occurred equally well in p53 wild-type (MKN-45, or in p53 mutant-type (MKN-28 gastric cancer cells. Conclusions The data presented suggests that overexpression of the BAK gene can lead to apoptosis of gastric cancer cells in vitro, which does not appear to be dependent on p53 status. The action mechanism of BAK mediated apoptosis correlates with activation of caspase-3. This could be served as a potential strategy for further development of gastric cancer therapies.

  2. BAK overexpression mediates p53-independent apoptosis inducing effects on human gastric cancer cells

    International Nuclear Information System (INIS)

    Tong, Qiang-Song; Zheng, Li-Duan; Wang, Liang; Liu, Jun; Qian, Wei

    2004-01-01

    BAK (Bcl-2 homologous antagonist/killer) is a novel pro-apoptotic gene of the Bcl-2 family. It has been reported that gastric tumors have reduced BAK levels when compared with the normal mucosa. Moreover, mutations of the BAK gene have been identified in human gastrointestinal cancers, suggesting that a perturbation of BAK-mediated apoptosis may contribute to the pathogenesis of gastric cancer. In this study, we explored the therapeutic effects of gene transfer mediated elevations in BAK expression on human gastric cancer cells in vitro. Eukaryotic expression vector for the BAK gene was constructed and transferred into gastric cancer cell lines, MKN-45 (wild-type p53) and MKN-28 (mutant-type p53). RT-PCR and Western Blotting detected cellular BAK gene expression. Cell growth activities were detected by MTT colorimetry and flow cytometry, while apoptosis was assayed by electronic microscopy and TUNEL. Western Blotting and colorimetry investigated cellular caspase-3 activities. BAK gene transfer could result in significant BAK overexpression, decreased in vitro growth, cell cycle G 0 /G 1 arrest, and induced apoptosis in gastric cancer cells. In transferred cells, inactive caspase-3 precursor was cleaved into the active subunits p20 and p17, during BAK overexpression-induced apoptosis. In addition, this process occurred equally well in p53 wild-type (MKN-45), or in p53 mutant-type (MKN-28) gastric cancer cells. The data presented suggests that overexpression of the BAK gene can lead to apoptosis of gastric cancer cells in vitro, which does not appear to be dependent on p53 status. The action mechanism of BAK mediated apoptosis correlates with activation of caspase-3. This could be served as a potential strategy for further development of gastric cancer therapies

  3. A dynamic P53-MDM2 model with time delay

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-11-15

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

  4. A dynamic P53-MDM2 model with time delay

    International Nuclear Information System (INIS)

    Mihalas, Gh.I.; Neamtu, M.; Opris, D.; Horhat, R.F.

    2006-01-01

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

  5. Role of P53 in Mammary Epithelial Cell Senescence

    National Research Council Canada - National Science Library

    Dimri, Goberdhan P

    2006-01-01

    .... We also chose several other targets of p53 that are induced by DNA damage. The RT PCR analysis aws carried out using mRNA prepared from young growing early passage and senescent late passage HMECs...

  6. Polymorphism at codon 36 of the p53 gene.

    Science.gov (United States)

    Felix, C A; Brown, D L; Mitsudomi, T; Ikagaki, N; Wong, A; Wasserman, R; Womer, R B; Biegel, J A

    1994-01-01

    A polymorphism at codon 36 in exon 4 of the p53 gene was identified by single strand conformation polymorphism (SSCP) analysis and direct sequencing of genomic DNA PCR products. The polymorphic allele, present in the heterozygous state in genomic DNAs of four of 100 individuals (4%), changes the codon 36 CCG to CCA, eliminates a FinI restriction site and creates a BccI site. Including this polymorphism there are four known polymorphisms in the p53 coding sequence.

  7. 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.

  8. Thymocyte apoptosis induced by p53-dependent and independent pathways

    International Nuclear Information System (INIS)

    Clarke, A.R.; Purdie, C.A.; Harrison, D.J.; Morris, R.G.; Bird, C.C.; Hooper, M.L.; Wyllie, A.H.

    1993-01-01

    The authors studied the dependence of apoptosis on p53 expression in cells from the thymus cortex. Short-term thymocyte cultures were prepared from mice constitutively heterozygous or homozygous for a deletion in the p53 gene introduced into the germ line after gene targeting. Wild-type thymocytes readily undergo apoptosis after treatment with ionizing radiation, the glucocorticoid methylprednisolone, or etoposide (an inhibitor of topoisomerase II), or after Ca 2+ -dependent activation by phorbol ester and a calcium ionophore. In contrast, homozygous null p53 thymocytes are resistant to induction of apoptosis by radiation or etoposide, but retain normal sensitivity to glucocorticoid and calcium. The time-dependent apoptosis that occurs in untreated cultures is unaffected by p53 status. Cells heterozygous for p53 deletion are partially resistant to radiation and etoposide. Results show that p53 exerts a significant and dose-dependent effect in the initiation of apoptosis, but only when it is induced by agents that cause DNA-strand breakage. (Author)

  9. 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.

  10. p53-Independent thermosensitization by mitomycin C in human non-small cell lung carcinoma cells

    International Nuclear Information System (INIS)

    Jin, Z.-H.; Matsumoto, H.; Hayashi, S.; Shioura, H.; Kitai, R.; Kano, E.; Hatashita, M.

    2003-01-01

    The combined treatment with hyperthermia and chemotherapeutic drugs such as cisplatin (CDDP), doxorubicin (DOX) and mitomycin C (MMC) has been widely adopted as a strategy of interdisciplinary cancer therapy to obtain greater therapeutic benefits. However, the involved mechanisms of the interactive cytotoxic effects of hyperthermia and MMC remain unclear. To elucidate the relationship between p53 functions and the interactive effects of the combined treatment with mild-hyperthermia and MMC, we examined the potentiation of cytotoxic effects, the induction of apoptosis, the changes in cell cycles and the accumulation of Hsp72 after the combined treatment with hyperthermia at 42 degree C and MMC using human non-small cell lung carcinoma H1299 transfectants with either null, wild-type (wt) or mutant (m) p53 gene. H1299/null, H1299/wtp53 and H1299/mp53 cells showed similar sensitivities to either hyperthermia at 42 degree C alone or MMC alone. The combined treatment resulted in a synergistically enhanced cytotoxicity in H1299 transfectants in a p53-independent manner. The mechanisms involved an enhancement of heat-induced apoptosis and a modulation of the cell cycle distribution by the combined treatment. The accumulation of Hsp72 was not suppressed by the combined treatment, as is not the case of the combined treatment with hyperthermia and either CDDP (1) or bleomycin (2). Our findings demonstrate a p53-independent mechanism for a synergistically cytotoxic enhancement by the combined treatment with mild-hyperthermia and MMC

  11. Role of p53 status in radiation sensitivity and cell cycle progression

    International Nuclear Information System (INIS)

    Zellars, Richard C.; Loney, Tania; Schott, Ann F.; Davis, Mary A.; Maybaum, Jonathan; Clarke, Michael F.; Lawrence, Theodore S.

    1995-01-01

    Purpose: Although p53 function plays a major role in G1 arrest after radiation, the influence of p53 status on progress through other phases of the cell cycle and on radiation sensitivity of human tumors is less clear. We investigated these issues using cells with a conditional expression system for wild type p53. Methods: A temperature sensitive murine wild type p53 plasmid was used (Ginsberg D, et al: Mol. Cell.Biol . 11:582, 1991). At the permissive temperature (32 deg. C), this plasmid produces a protein which assumes a conformation that exhibits wild type p53 function. However, when cells are cultured at 38 deg. C, this protein assumes an inactive conformation. HT29 human colon cancer cells (which are p53 mutant) were transduced with this plasmid (designated PEP A and PEP G cells) or a control vector (designated CCH1 cells) using electroporation and Geneticin selection. The presence of murine p53 transcript in the PEP cells was confirmed by Northern analysis. Results: Cells were cultured under 3 conditions: 1) 38 deg. C at all times; 2) 32 deg. C for 24 hours prior to irradiation and 3) 32 deg. C for 24 hours after irradiation. We found that culturing under permissive temperatures produced a small decrease in surviving fraction in the PEP clones (0.61 ± 0.10 and 0.64 ± 0.07, for PEP A and G, respectively) but not the CCH1 controls (1.14 ± 0.15). PEP cells tended to be more radiosensitive than CCH1 cells (even under non-permissive conditions) and demonstrated a trend towards increased radiosensitivity under both Conditions 2 and 3. In addition, flow cytometry revealed that a 24 hour exposure to permissive conditions increased the fraction of cells in G1 slightly and in G2/M substantially. S phase was almost absent. Conclusion: Restoration of p53 function in HT29 human colon cancer cells using this temperature sensitive system produced increased cytotoxicity and radiation sensitivity as well as cell cycle redistribution. It will be important to assess the

  12. Phosphorylation of Tip60 by GSK-3 determines the induction of PUMA and apoptosis by p53

    Science.gov (United States)

    Charvet, Céline; Wissler, Manuela; Brauns-Schubert, Prisca; Wang, Shang-Jui; Tang, Yi; Sigloch, Florian C.; Mellert, Hestia; Brandenburg, Martin; Lindner, Silke E.; Breit, Bernhard; Green, Douglas R.; McMahon, Steven B.; Borner, Christoph; Gu, Wei; Maurer, Ulrich

    2011-01-01

    Summary Activation of p53 by DNA damage results in either cell cycle arrest, allowing DNA repair and cell survival, or induction of apoptosis. As these opposite outcomes are both mediated by p53 stabilization, additional mechanisms to determine this decision must exist. Here we show that glycogen synthase kinase-3 (GSK-3) is required for the p53-mediated induction of the pro-apoptotic BH3 only-protein PUMA, an essential mediator of p53-induced apoptosis. Inhibition of GSK-3 protected from cell death induced by DNA damage and promoted increased long-term cell survival. We demonstrate that GSK-3 phosphorylates serine 86 of the p53-acetyltransferase Tip60. A Tip60S86A mutant was less active to induce p53 K120 acetylation, Histone 4 acetylation and expression of PUMA. Our data suggest that GSK-3 mediated Tip60S86-phosphorylation provides a link between PI3K signaling and the choice for or against apoptosis induction by p53. PMID:21658600

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

    International Nuclear Information System (INIS)

    Corujo, G.; Campagno, R.; Rivera Pomar, R.; Ferrero, P.; Lu, W.J.

    2011-01-01

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

  14. 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.

  15. 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.

  16. 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.

  17. A Small Ras-like protein Ray/Rab1c modulates the p53-regulating activity of PRPK

    International Nuclear Information System (INIS)

    Abe, Yasuhito; Takeuchi, Takashi; Imai, Yoshinori; Murase, Ryuichi; Kamei, Yoshiaki; Fujibuchi, Taketsugu; Matsumoto, Suguru; Ueda, Norifumi; Ogasawara, Masahito; Shigemoto, Kazuhiro; Kito, Katsumi

    2006-01-01

    PRPK phosphorylates serine-15 residue of p53 and enhances transcriptional activity. PRPK possesses a bipartite nuclear localization signal and localizes in nucleus when over-expressed in cells. However, intrinsic PRPK localizes mainly in the cytosol in situ. While studying the mechanisms in the distribution of intrinsic PRPK, we identified a PRPK binding protein, an ubiquitously expressed Small Ras-like GTPase, Rab1c, also named Ray or Rab35. The over-expressed Ray was distributed in the nucleus, cytosol, and cell membrane. Both Ray wild type and GTP-restrictively binding mutant Ray-Q67L, but not guanine nucleotide unstable binding mutant Ray-N120I, partially distributed the over-expressed PRPK to the cytosol and also suppressed the PRPK-induced p53-transcriptional activity profoundly. A Small Ras-like GTPase protein Ray was thus indicated to modulate p53 transcriptional activity of PRPK

  18. G2-block after irradiation of cells with different p53 status

    Energy Technology Data Exchange (ETDEWEB)

    Zoelzer, Friedo [University of South Bohemia in Ceske Budejovice, Department of Radiology, Toxicology and Civil Protection, Faculty of Health and Social Studies, Ceske Budejovice (Czech Republic); University Duisburg-Essen, Institute of Medical Radiobiology, Medical Faculty, Essen (Germany); Jagetia, Ganesh [University Duisburg-Essen, Institute of Medical Radiobiology, Medical Faculty, Essen (Germany); Mizoram University, Department of Zoology, School of Life Sciences, Aizawl (India); Streffer, Christian [University Duisburg-Essen, Institute of Medical Radiobiology, Medical Faculty, Essen (Germany)

    2014-11-15

    Although it is clear that functional p53 is not required for radiation-induced G{sub 2} block, certain experimental findings suggest a role for p53 in this context. For instance, as we also confirm here, the maximum accumulation in the G{sub 2} compartment after X-ray exposure occurs much later in p53 mutants than in wild types. It remains to be seen, however, whether this difference is due to a longer block in the G{sub 2} phase itself. We observed the movement of BrdU-labeled cells through G{sub 2} and M into G{sub 1}. From an analysis of the fraction of labeled cells that entered the second posttreatment cell cycle, we were able to determine the absolute duration of the G{sub 2} and M phases in unirradiated and irradiated cells. Our experiments with four cell lines, two melanomas and two squamous carcinomas, showed that the radiation-induced delay of transition through the G{sub 2} and M phases did not correlate with p53 status. We conclude that looking at the accumulation of cells in the G{sub 2} compartment alone is misleading when differences in the G{sub 2} block are investigated and that the G{sub 2} block itself is indeed independent of functional p53. (orig.) [German] Obwohl klar ist, dass ein funktionelles p53-Protein fuer die Ausbildung des strahleninduzierten G{sub 2}-Blocks nicht zwingend erforderlich ist, gibt es experimentelle Befunde, die nahe legen, dass p53 in diesem Zusammenhang doch eine gewisse Rolle spielt. Zum Beispiel bestaetigen wir hier fruehere Berichte, dass die Akkumulation von Zellen im G{sub 2}-Kompartiment bei p53-Mutanten deutlich spaeter nach Bestrahlung ihr Maximum erreicht als bei p53-Wildtypen. Es bleibt jedoch zu klaeren, ob dieser Unterschied seinen Grund in einem laengeren Block der G{sub 2}-Phase selbst hat. Beobachtet wurde die Bewegung von BrdU-markierten Zellen durch G{sub 2} und M nach G{sub 1}. Aus der zeitlichen Veraenderung des Anteils markierter Zellen im G{sub 1}-Kompartiment des naechsten Zellzyklus konnte die

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-15

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

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

    International Nuclear Information System (INIS)

    Otozai, Shinji; Ishikawa-Fujiwara, Tomoko; Oda, Shoji; Kamei, Yasuhiro; Ryo, Haruko; Sato, Ayuko; Nomura, Taisei; Mitani, Hiroshi; Tsujimura, Tohru; Inohara, Hidenori; Todo, Takeshi

    2014-01-01

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

  1. Sequence specific DNA binding by P53 is enhanced by ionizing radiation and is mediated via DNA-PK activity

    International Nuclear Information System (INIS)

    Kachnic, L.A.; Wunsch, H.; Mekeel, K.L.; De Frank, J.S.; Powell, S.N.

    1996-01-01

    Purpose: P53 is known to be involved in the cellular response to DNA damage. It mediates many of its effects by acting as a transcription factor via sequence-specific DNA binding. The half-life of p53 is prolonged following DNA damage, and this results in elevated levels of p53 for a period of 2-8 hours. The increase in p53 is often relatively small, but this produces significant stimulation of a downstream gene such as p21(WAF1/cip1). We investigated post-translational modification of p53 following ionizing radiation damage. Materials and Methods: The response of normal Balb-C mouse fibroblasts (FC) to ionizing radiation (IR, 8 Gy) was measured at 0,3,6,9 and 24 hours, by the levels of p53, p21, flow cytometry and the electrophoretic mobility shift assay (EMSA). EMSA utilized a 26 bp consensus sequence end-labeled oligonucleotide to measure sequence-specific p53 binding. P53 specificity was confirmed by an enhanced mobility shift (retardation) when using p53 antibody. Comparison was made with scid fibroblasts (FS) and FC cells transfected with a plasmid (CX3) containing mutant p53 (alanine-143) or infected with a retrovirus containing the E6 protein of human papilloma virus type 16. Results: The response of p53 to DNA damage shows a 3-fold increase at 3-6 hours, and was not significantly different between FC and FS. FC-CX3 showed detectable basal levels of p53, and a 2-fold further induction of p53 after IR. FC-E6 showed no detectable levels of p53 before or after IR. No induction of p21 or G1/S arrest was seen in FC-CX3 or FC-E6, as has been observed previously. The induction of p21 in FS cells was attenuated and delayed: a 2-3-fold increase seen maximally at 9 hours, compared with a 5-fold increase seen maximally at 3-6 hours in FC cells. The accumulation of cells at the G1/S junction after IR showed the same kinetics as p21 induction: the peak of cells in G1 occurs at 3-6 hours in FC, but not until 9-24 hours in FS. The response is reminiscent of that seen in

  2. 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

  3. Super p53 for Treatment of Ovarian Cancer

    Science.gov (United States)

    2017-09-01

    System 3, Clontech) containing wt-p53, p53-CC, and ZsGreen (control) were made. Ad-ZsGreen was tested in ID8 cells, which showed very high expression...views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army...MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION / AVAILABILITY STATEMENT Approved for Public Release; Distribution Unlimited 13. SUPPLEMENTARY NOTES 14

  4. Concurrent overexpression of serum p53 mutation related with Helicobacter pylori infection

    Directory of Open Access Journals (Sweden)

    Lorenzo-Peñuelas Antonio

    2010-06-01

    Full Text Available Abstract Background & Aims In the province of Cadiz (Spain, the adjusted mortality rate for gastric cancer in the coastal town of Barbate is 10/100.000 inhabitants, whereas in the inland town of Ubrique, the rate is twice as high. The rate of Helicobacter pylori (H. pylori infection (H. pylori antibodies in the normal population was 54% in Ubrique, but only 32% in Barbate. In the two decades since its original discovery, p53 has found a singularly prominent place in our understanding of human gastric cancer and H. pylori cause accumulation of reactive oxygen species in the mucosa compartment. This study was designed to compare serum levels of p53 in a population characterized by high mortality due to stomach cancer and a high prevalence of H. pylori infection and another population in which mortality from this cause and the prevalence of H. pylori infection are low. Materials and methods 319 subjects from the low mortality population and 308 from the high mortality population were studied, as were 71 patients with stomach cancer. We measured serum immunoglobulin G antibody to H. pylori and serum mutant p53 protein and ceruloplasmin. Results The difference between the two populations in the prevalence of H. pylori infection was significant (p Conclusions There is a significant association between infection with H. pylori, elevated titers of H. pylori antibodies, and positivity for serum mutant p53 protein. Such information can significantly increase our basic knowledge in molecular pathology of gastric cancer and protection against H. pylori infection.

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

    International Nuclear Information System (INIS)

    Bristow, Robert G.; Benchimol, Samuel; Hill, Richard P.

    1996-01-01

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

  6. 1800MHz Microwave Induces p53 and p53-Mediated Caspase-3 Activation Leading to Cell Apoptosis In Vitro.

    Directory of Open Access Journals (Sweden)

    Fuqiang Xing

    Full Text Available Recent studies have reported that exposure of mammalian cells to microwave radiation may have adverse effects such as induction of cell apoptosis. However, the molecular mechanisms underlying microwave induced mammalian cell apoptosis are not fully understood. Here, we report a novel mechanism: exposure to 1800MHz microwave radiation induces p53-dependent cell apoptosis through cytochrome c-mediated caspase-3 activation pathway. We first measured intensity of microwave radiation from several electronic devices with an irradiation detector. Mouse NIH/3T3 and human U-87 MG cells were then used as receivers of 1800MHz electromagnetic radiation (EMR at a power density of 1209 mW/m2. Following EMR exposure, cells were analyzed for viability, intracellular reactive oxygen species (ROS generation, DNA damage, p53 expression, and caspase-3 activity. Our analysis revealed that EMR exposure significantly decreased viability of NIH/3T3 and U-87 MG cells, and increased caspase-3 activity. ROS burst was observed at 6 h and 48 h in NIH/3T3 cells, while at 3 h in U-87 MG cells. Hoechst 33258 staining and in situ TUNEL assay detected that EMR exposure increased DNA damage, which was significantly restrained in the presence of N-acetyl-L-cysteine (NAC, an antioxidant. Moreover, EMR exposure increased the levels of p53 protein and p53 target gene expression, promoted cytochrome c release from mitochondrion, and increased caspase-3 activity. These events were inhibited by pretreatment with NAC, pifithrin-α (a p53 inhibitor and caspase inhibitor. Collectively, our findings demonstrate, for the first time, that 1800MHz EMR induces apoptosis-related events such as ROS burst and more oxidative DNA damage, which in turn promote p53-dependent caspase-3 activation through release of cytochrome c from mitochondrion. These findings thus provide new insights into physiological mechanisms underlying microwave-induced cell apoptosis.

  7. 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.

  8. 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.

  9. Overexpression of p53 in Nigerian breast cancers and its ...

    African Journals Online (AJOL)

    This study sought to determine the expression of p53 protein as well as the relationship with oestrogen receptor (ER) and progesterone receptor (PR) proteins. Methodology: Formalin-fixed, paraffin-embedded tissue samples of diagnosed invasive breast cancer were obtained from the Department of Anatomic and ...

  10. p53 expression in colorectal carcinoma in relation to ...

    African Journals Online (AJOL)

    Haematoxylin and eosin stain was used for evaluation of histological types and degree of differentiation of the tumors. Topography of the tumors and demographic data were obtained from accompanying histological request forms. Results: Out of 109 patient\\'s tissue blocks that were studied, 61 cases (56%) expressed p53 ...

  11. Cellular inactivation of nitric oxide induces p53-dependent ...

    African Journals Online (AJOL)

    Tropical Journal of Pharmaceutical Research August 2016; 15 (8): 1595-1603 ... Cellular inactivation of nitric oxide induces p53-dependent apoptosis in ... apoptosis induced by a selective iNOS inhibitor, N-[(3-aminomethyl) benzyl] acetamidine (1400W), .... and nitrate. ... Nitrite production was measured in culture media.

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

    Directory of Open Access Journals (Sweden)

    Katrin Friedrich

    1997-01-01

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

  13. Apoptosis in spermatogonia irradiated P53 null mice

    International Nuclear Information System (INIS)

    Streit-Bianchi, M.; Hendry, J.H.; Roberts, S.A.; Morris, J.D.; Durgaryan, A.A.

    2007-01-01

    Complete text of publication follows. The exposure of germ cells to ionizing radiations is of concern both from high-dose therapeutic exposures and from low doses causing deleterious trans-generational mutations. P53 protein plays an important role in cellular damage and is expressed in the testis normally during meiosis, its expression being localised to the preleptotene and early/mid pachytene spermatocytes. P53 null mice, heterozygotes possessing a 129 Sv/C57BL6 genetic background and B6D2F1 mice have been irradiated to 1 and 2 Gy single doses. Fractionated exposures of 1+1 Gy at 4 hours interval were also carried out. Apoptosis induction, spermatogonia and spermatocytes survival were assessed by microscope analysis of histological samples at 4 to 96 hours after irradiation in time-course experiments. The same end-points were also assessed at 72 and 96 hours after irradiation to single doses in the region between 20cGy to 2Gy. A dose dependent level of p53 expression was observed at 4 hours after irradiation to 1 and 2 Gy which returned to normal level by 24 hours. Our data support a two process mode of apoptosis with a first wave around 12 hours followed by a second wave at 2-3 days. The first wave apoptosis is substantially reduced in p53 null mice whereas the second wave is reduced in B6D2F1 mice. The initial increase in apoptosis was delayed in some stages of the of germ cells development which were identified by the spermatids shape. Clear correlation exists between apoptosis and survival assessed in stage XI-XII Tubules 72 hours after irradiation. The data are in agreement with other data in literature indicating that irradiated spermatogonia die through apoptosis. The lack of apoptosis observed in p53 null mice results in a very high survival rate of daughter cells assessed later. Theses spermatocytes and the following progenitor cells are likely to carry mutations as most will not die in the smaller second wave of apoptosis observed 3 days after

  14. Polymorphisms in promoter sequences of MDM2, p53, and p16INK4a genes in normal Japanese individuals

    Directory of Open Access Journals (Sweden)

    Yasuhito Ohsaka

    2010-01-01

    Full Text Available Research has been conducted to identify sequence polymorphisms of gene promoter regions in patients and control subjects, including normal individuals, and to determine the influence of these polymorphisms on transcriptional regulation in cells that express wild-type or mutant p53. In this study we isolated genomic DNA from whole blood of healthy Japanese individuals and sequenced the promoter regions of the MDM2, p53, and p16INK4a genes. We identified polymorphisms comprising 3 nucleotide substitutions at exon 1 and intron 1 regions of the MDM2 gene and 1 nucleotide insertion at a poly(C nucleotide position in the p53 gene. The Japanese individuals also exhibited p16INK4a polymorphisms at several positions, including position -191. Reporter gene analysis by using luciferase revealed that the polymorphisms of MDM2, p53, and p16INK4a differentially altered luciferase activities in several cell lines, including the Colo320DM, U251, and T98G cell lines expressing mutant p53. Our results indicate that the promoter sequences of these genes differ among normal Japanese individuals and that polymorphisms can alter gene transcription activity.

  15. Effect of UV C irradiation on P53 in FADD+/+ and FADD-/- cells

    International Nuclear Information System (INIS)

    Matic, Igor; Radnic, Maja; Marijanovic, Inga; Furcic, Ivana; Nagy, Biserka

    2008-01-01

    The dominant paradigm of tumor biology is that evasion from apoptosis is one of the crucial features of malignant diseases and that the efficiency of cancer therapy depends on P53-dependent apoptosis. Because of the importance of apoptotic pathways in protecting cells against malignant transformation, disruption of apoptosis is extremely common in cancer cells, and is frequently due to mutations in the P53 tumor suppressor gene. Fas-associated death domain (FADD) is an adapter protein that is required for apoptosis induced by all known death receptors. FADD is implicated in death receptor-independent apoptotic response, such as DNA damage. We used embryonic fibroblasts derived from FADD knockout mice and their genetic counterparts. We predicted that UV exposure induces a loss of FADD function and leads to mutations in P53. Loss of FADD expression causes deregulation of apoptosis and expansion of mutated cells and initiation of cancer. We predicted that FADD dysfunction may be potentially advantageous for tumor growth and that FADD can act as a tumor suppressor. Cells were irradiated with UV C light (254 nm) using a germicidal lamp (Upland, CA). The culture media was drained before the irradiation and fresh media was added after. In the first experiment we irradiated cells with a dose of 25 J/m 2 and after 5 days we isolated genomic DNA but part of the cells were irradiated again with the same dose. After 5 days DNA were isolated so the cumulative irradiation dose was 50 J/m 2 . In the second experiment cells were irradiated ones with the dose of 40 J/m 2 and DNA was isolated after 18 days. Lethal dosage for each cell line is 50 J/m 2 . Genomic DNA was analyzed by allele-specific polymerase chain reaction (AS-PCR) for CC to TT mutation at codons 154-155 and 175-176 in exon 5 and for C to T mutations at codons 270 and 275 in exon 8 of the P53 gene. The mutant-specific forward primer was used for each mutation. The reverse primers for amplification of mutations were

  16. Transactivation of bad by vorinostat-induced acetylated p53 enhances doxorubicin-induced cytotoxicity in cervical cancer cells.

    Science.gov (United States)

    Lee, Sook-Jeong; Hwang, Sung-Ook; Noh, Eun Joo; Kim, Dong-Uk; Nam, Miyoung; Kim, Jong Hyeok; Nam, Joo Hyun; Hoe, Kwang-Lae

    2014-02-14

    Vorinostat (VOR) has been reported to enhance the cytotoxic effects of doxorubicin (DOX) with fewer side effects because of the lower DOX dosage in breast cancer cells. In this study, we investigated the novel mechanism underlying the synergistic cytotoxic effects of VOR and DOX co-treatment in cervical cancer cells HeLa, CaSki and SiHa cells. Co-treatment with VOR and DOX at marginal doses led to the induction of apoptosis through caspase-3 activation, poly (ADP-ribose) polymerase cleavage and DNA micronuclei. Notably, the synergistic growth inhibition induced by the co-treatment was attributed to the upregulation of the pro-apoptotic protein Bad, as the silencing of Bad expression using small interfering RNA (siRNA) abolished the phenomenon. As siRNA against p53 did not result in an increase in acetylated p53 and the consequent upregulation of Bad, the observed Bad upregulation was mediated by acetylated p53. Moreover, a chromatin immunoprecipitation analysis showed that the co-treatment of HeLa cells with VOR and DOX increased the recruitment of acetylated p53 to the bad promoter, with consequent bad transactivation. Conversely, C33A cervical cancer cells containing mutant p53 co-treated with VOR and DOX did not exhibit Bad upregulation, acetylated p53 induction or consequent synergistic growth inhibition. Together, the synergistic growth inhibition of cervical cancer cell lines induced by co-treatment with VOR and DOX can be attributed to the upregulation of Bad, which is induced by acetylated p53. These results show for the first time that the acetylation of p53, rather than histones, is a mechanism for the synergistic growth inhibition induced by VOR and DOX co-treatments.

  17. Connection between cell phone use, p53 gene expression in different zones of glioblastoma multiforme and survival prognoses

    Directory of Open Access Journals (Sweden)

    Reza Akhavan-Sigari

    2014-08-01

    Full Text Available The aim of this paper is to investigate p53 gene expression in the central and peripheral zones of glioblastoma multiforme using a real-time reverse transcription polymerase chain reaction (RT-PCR technique in patients who use cell phones ≥3 hours a day and determine its relationship to clinicopathological findings and overall survival. Sixty-three patients (38 males and 25 females, diagnosed with glioblastoma multiforme (GBM, underwent tumor resection between 2008 and 2011. Patient ages ranged from 25 to 88 years, with a mean age of 55. The levels of expression of p53 in the central and peripheral zone of the GBM were quantified by RT-PCR. Data on p53 gene expression from the central and peripheral zone, the related malignancy and the clinicopatholagical findings (age, gender, tumor location and size, as well as overall survival, were analyzed. Forty-one out of 63 patients (65% with the highest level of cell phone use (≥3 hours/day had higher mutant type p53 expression in the peripheral zone of the glioblastoma; the difference was statistically significant (P=0.034. Results from the present study on the use of mobile phones for ≥3 hours a day show a consistent pattern of increased risk for the mutant type of p53 gene expression in the peripheral zone of the glioblastoma, and that this increase was significantly correlated with shorter overall survival time. The risk was not higher for ipsilateral exposure. We found that the mutant type of p53 gene expression in the peripheral zone of the glioblastoma was increased in 65% of patients using cell phones ≥3 hours a day.

  18. p53 regulates the repair of DNA double-strand breaks by both homologous and non-homologous recombination

    International Nuclear Information System (INIS)

    Willers, H.; Powell, S.N.; Dahm-Daphi, J.

    2003-01-01

    Full text: p53 is known to suppress spontaneous homologous recombination (HR), while its role in non-homologous recombination (NHR) remains to be clarified. Here, we sought to determine the influence of p53 on the repair of chromosomal double-strand breaks (DSBs) by HR or NHR using specially designed recombination substrates that integrate into the genome. Isogenic mouse fibroblast pairs with or without expression of exogenous p53 protein were utilized. A reporter plasmid carrying a mutated XGPRT gene was chromosomally integrated and DSBs were generated within the plasmid by the I-SceI endonuclease. Subsequent homology-mediated repair from an episomal donor resulted in XGPRT reconstitution and cellular resistance to a selection antibiotic. Analogously, the repair of chromosomal I-SceI breaks by NHR using another novel reporter plasmid restored XGPRT translation. For p53-null cells, the mean frequency of I-SceI break repair via HR was 5.5 x 10 -4 . The p53-Val135 mutant, which previously has been shown to suppress spontaneous HR by 14-fold employing the same cell system and reporter gene, only caused a 2- to 3-fold suppression of break-induced HR. In contrast, a dramatic effect of p53 on repair via NHR was found. Preliminary sequence analysis indicated that there was at least a 1000-fold reduction of illegitimate repair events resulting in loss of sequence at the break sites. The observed effects were mediated by p53 mutants defective in regulation of the cell-cycle and apoptosis. The main findings were: (1) p53 virtually blocked illegitimate rejoining of chromosomal ends. (2) The suppression of homologous DSB repair was less pronounced than the inhibition of spontaneous HR. We hypothesize that p53 allows to a certain extent error-free homology-dependent repair to proceed, while blocking error-prone NHR. The data support and extent a previous model, in which p53 maintains genomic stability by regulating recombination independently of its transactivation function

  19. 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

  20. Differential sensitivity of p53+ and p53- cells to caffeine-induced radiosensitization and override of G2 delay

    International Nuclear Information System (INIS)

    Powell, S.N.; DeFrank, J.S.; Connell, P.; Eogan, M.; Preffer, F.; Dombkowski, D.; Tang, W.; Friend, S.H.

    1995-01-01

    Purpose: Most drug discovery efforts have focused on finding new DNA damaging agents to kill tumor cells preferentially. An alternative approach is to find ways to increase tumor specific killing by modifying tumor specific responses to that damage. We asked whether cells lacking the G1/S arrest in response to X-rays are more sensitive to X-ray damage when treated with agents that override G2/M arrest. Materials and Methods: Mouse embryonic fibroblasts genetically matched to be (+/+) or (-/-) p53 and rat embryonic fibroblasts (REF) made (+) or (-) for wild-type p53 function by transfection were irradiated with and without caffeine, a known checkpoint inhibitor. Caffeine treatment was maintained for 24 hours from 1 hour prior to irradiation. Cell survival following ionizing radiation was measured by clonogenic assay. For cell-cycle analysis, cells were in exponential asynchronous growth at the time of irradiation. The proportion of cells in G1, S and G2/M phases of the cell cycle were recorded immediately before and following irradiation and subsequently at 3,6,9,12,24 and 48 hours following irradiation. Results: Caffeine was found to cause radiosensitzation at low dose (0.5mM) in (-/-) cells but not in (+/+) cells. The sensitization enhancement ratio (SER) was 1.45 at 0.1 survival and 1.56 at 0.01 survival. At this dose of caffeine, this SER reflected therapeutic gain as there was no detectable effect on (+/+) cells. At 1mM caffeine, sensitization of (-/-) cells was 1.77, but (+/+) cells now also showed sensitization (SER=1.25). In (-/-) cells at 0.1mM caffeine the SER was 1.5 at 0.01 survival. The transfected REF cells (functionally null for p53) also exhibited caffeine-induced radiosensitization at both 0.5 and 2mM caffeine with a SER 1.45 for 2mM at 0.1 survival. No significant sensitization could be demonstrated for REF cells at the same doses of caffeine. The REF cells, with wild-type p53, transfected with pCMVneo alone showed no change in radiosensitivity or

  1. p53 protects against genome instability following centriole duplication failure

    Science.gov (United States)

    Lambrus, Bramwell G.; Uetake, Yumi; Clutario, Kevin M.; Daggubati, Vikas; Snyder, Michael; Sluder, Greenfield

    2015-01-01

    Centriole function has been difficult to study because of a lack of specific tools that allow persistent and reversible centriole depletion. Here we combined gene targeting with an auxin-inducible degradation system to achieve rapid, titratable, and reversible control of Polo-like kinase 4 (Plk4), a master regulator of centriole biogenesis. Depletion of Plk4 led to a failure of centriole duplication that produced an irreversible cell cycle arrest within a few divisions. This arrest was not a result of a prolonged mitosis, chromosome segregation errors, or cytokinesis failure. Depleting p53 allowed cells that fail centriole duplication to proliferate indefinitely. Washout of auxin and restoration of endogenous Plk4 levels in cells that lack centrioles led to the penetrant formation of de novo centrioles that gained the ability to organize microtubules and duplicate. In summary, we uncover a p53-dependent surveillance mechanism that protects against genome instability by preventing cell growth after centriole duplication failure. PMID:26150389

  2. Low doses of arsenic, via perturbing p53, promotes tumorigenesis

    Energy Technology Data Exchange (ETDEWEB)

    Ganapathy, Suthakar, E-mail: s.ganapathy@neu.edu [Center for Drug Development, Northeastern University, Boston (United States); Li, Ping [The First Affiliated Hospital, Zhengzhou University, Zhengzhou (China); The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg (Sweden); Fagman, Johan [The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg (Sweden); Yu, Tianqi; Lafontant, Jean [Center for Drug Development, Northeastern University, Boston (United States); Zhang, Guojun [The First Affiliated Hospital, Zhengzhou University, Zhengzhou (China); Chen, Changyan [Center for Drug Development, Northeastern University, Boston (United States); The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg (Sweden)

    2016-09-01

    In drinking water and in workplace or living environments, low doses of arsenic can exist and operate as a potent carcinogen. Due to insufficient understanding and information on the pervasiveness of environmental exposures to arsenic, there is an urgent need to elucidate the underlying molecular mechanisms of arsenic regarding its carcinogenic effect on human health. In this study, we demonstrate that low doses of arsenic exposure mitigate or mask p53 function and further perturb intracellular redox state, which triggers persistent endoplasmic reticulum (ER) stress and activates UPR (unfolded protein response), leading to transformation or tumorigenesis. Thus, the results suggest that low doses of arsenic exposure, through attenuating p53-regulated tumor suppressive function, change the state of intracellular redox and create a microenvironment for tumorigenesis. Our study also provides the information for designing more effective strategies to prevent or treat human cancers initiated by arsenic exposure.

  3. 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...

  4. Low doses of arsenic, via perturbing p53, promotes tumorigenesis

    International Nuclear Information System (INIS)

    Ganapathy, Suthakar; Li, Ping; Fagman, Johan; Yu, Tianqi; Lafontant, Jean; Zhang, Guojun; Chen, Changyan

    2016-01-01

    In drinking water and in workplace or living environments, low doses of arsenic can exist and operate as a potent carcinogen. Due to insufficient understanding and information on the pervasiveness of environmental exposures to arsenic, there is an urgent need to elucidate the underlying molecular mechanisms of arsenic regarding its carcinogenic effect on human health. In this study, we demonstrate that low doses of arsenic exposure mitigate or mask p53 function and further perturb intracellular redox state, which triggers persistent endoplasmic reticulum (ER) stress and activates UPR (unfolded protein response), leading to transformation or tumorigenesis. Thus, the results suggest that low doses of arsenic exposure, through attenuating p53-regulated tumor suppressive function, change the state of intracellular redox and create a microenvironment for tumorigenesis. Our study also provides the information for designing more effective strategies to prevent or treat human cancers initiated by arsenic exposure.

  5. 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...

  6. P53-dependent antiproliferative and pro-apoptotic effects of trichostatin A (TSA) in glioblastoma cells.

    Science.gov (United States)

    Bajbouj, K; Mawrin, C; Hartig, R; Schulze-Luehrmann, J; Wilisch-Neumann, A; Roessner, A; Schneider-Stock, R

    2012-05-01

    Glioblastomas are known to be highly chemoresistant, but HDAC inhibitors (HDACi) have been shown to be of therapeutic relevance for this aggressive tumor type. We treated U87 glioblastoma cells with trichostatin A (TSA) to define potential epigenetic targets for HDACi-mediated antitumor effects. Using a cDNA array analysis covering 96 cell cycle genes, cyclin-dependent kinase inhibitor p21(WAF1) was identified as the major player in TSA-induced cell cycle arrest. TSA slightly inhibited proliferation and viability of U87 cells, cumulating in a G1/S cell cycle arrest. This effect was accompanied by a significant up-regulation of p53 and its transcriptional target p21(WAF1) and by down-regulation of key G1/S regulators, such as cdk4, cdk6, and cyclin D1. Nevertheless, TSA did not induce apoptosis in U87 cells. As expected, TSA promoted the accumulation of total acetylated histones H3 and H4 and a decrease in endogenous HDAC activity. Characterizing the chromatin modulation around the p21(WAF1) promoter after TSA treatment using chromatin immunoprecipitation, we found (1) a release of HDAC1, (2) an increase of acetylated H4 binding, and (3) enhanced recruitment of p53. p53-depleted U87 cells showed an abrogation of the G1/S arrest and re-entered the cell cycle. Immunofluorescence staining revealed that TSA induced the nuclear translocation of p21(WAF1) verifying a cell cycle arrest. On the other hand, a significant portion of p21(WAF1) was present in the cytoplasmic compartment causing apoptosis resistance. Furthermore, TSA-treated p53-mutant cell line U138 failed to show an induction in p21(WAF1), showed a deficient G2/M checkpoint, and underwent mitotic catastrophe. We suggest that HDAC inhibition in combination with other clinically used drugs may be considered an effective strategy to overcome chemoresistance in glioblastoma cells.

  7. Super p53 for Treatment of Ovarian Cancer

    Science.gov (United States)

    2017-09-01

    position, policy or decision unless so designated by other documentation. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public...a lead construct. Technical skills gained in the proposal include cell culture , transfections, microscopy, apoptosis assays, transcriptional assays...experiments complete 100% (DOD) Specific Aim 2: Deliver super p53 DNA with advanced polymeric systems alone and in combination with CPTX first in vitro

  8. 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...

  9. 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.

  10. Electrophoretic detection of protein p53 in human leukocytes

    International Nuclear Information System (INIS)

    Paponov, V.D.; Kupsik, E.G.; Shcheglova, E.G.; Yarullin, N.N.

    1986-01-01

    The authors have found an acid-soluble protein with mol. wt. of about 53 kD in peripheral blood leukocytes of persons with Down's syndrome. It was present in different quantities in all 20 patients tested, but was virtually not discovered in 12 healthy blood donors. This paper determines the possible identity of this protein with protein p53 from mouse ascites carcinoma by comparing their electrophoretic mobilities, because the accuracy of electrophoretic determination of the molecular weight of proteins is not sufficient to identify them. The paper also describes experiments to detect a protein with electrophoretic mobility identical with that of a protein in the leukocytes of patients with Down's syndrome in leukocytes of patients with leukemia. To discover if protein p53 is involved in cell proliferation, the protein composition of leukocytes from healthy blood donors, cultured in the presence and absence of phytohemagglutinin (PHA), was compared. Increased incorporation of H 3-thymidine by leukocytes of patients with Down's syndrome is explained by the presence of a population of immature leukocytes actively synthesizing DNA in the peripheral blood of these patients, and this can also explain the presence of protein p53 in the leukocytes of these patients

  11. Suicide genes or p53 gene and p53 target genes as targets for cancer gene therapy by ionizing radiation

    International Nuclear Information System (INIS)

    Liu Bing; Chinese Academy of Sciences, Beijing; Zhang Hong

    2005-01-01

    Radiotherapy has some disadvantages due to the severe side-effect on the normal tissues at a curative dose of ionizing radiation (IR). Similarly, as a new developing approach, gene therapy also has some disadvantages, such as lack of specificity for tumors, limited expression of therapeutic gene, potential biological risk. To certain extent, above problems would be solved by the suicide genes or p53 gene and its target genes therapies targeted by ionizing radiation. This strategy not only makes up the disadvantage from radiotherapy or gene therapy alone, but also promotes success rate on the base of lower dose. By present, there have been several vectors measuring up to be reaching clinical trials. This review focused on the development of the cancer gene therapy through suicide genes or p53 and its target genes mediated by IR. (authors)

  12. Bioluminescence Detection of Cells Having Stabilized p53 in Response to a Genotoxic Event

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    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.

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

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    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

  14. 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.

  15. 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

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

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    Debabani Ganguly

    2015-04-01

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

  17. 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

  18. p53 immunostaining is correlated with reduced survival and is not correlated with gene mutations in resected pulmonary large cell carcinomas

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    L.M. Massoni Neto

    2007-08-01

    Full Text Available Malignancy of pulmonary large cell carcinomas (LCC increases from classic LCC through LCC with neuroendocrine morphology (LCCNM to large cell neuroendocrine carcinomas (LCNEC. However, the histological classification has sometimes proved to be difficult. Because the malignancy of LCC is highly dependent on proteins with functions in the cell cycle, DNA repair, and apoptosis, p53 has been targeted as a potentially useful biological marker. p53 mutations in lung cancers have been shown to result in expression and protein expression also occurs in the absence of mutations. To validate the importance of both p53 protein expression (by immunostaining and p53 gene mutations in lung LCC (by PCR-single strand conformational polymorphism analysis of exons 5, 6, 7, and 8 and to study their relationships with clinical factors and sub-classification we investigated the correlation of p53 abnormalities in 15 patients with LCC (5 classic LCC, 5 LCNEC, and 5 LCCNM who had undergone resection with curative intent. Of these patients, 5/15 expressed p53 and none had mutant p53 sequences. There was a negative survival correlation with positive p53 immunostaining (P = 0.05. After adjustment for stage, age, gender, chemotherapy, radiotherapy, and histological subtypes by multivariate analysis, p53 expression had an independent impact on survival. The present study indicates that p53 assessment may provide an objective marker for the prognosis of LCC irrespective of morphological variants and suggests that p53 expression is important for outcome prediction in patients with the early stages of LCC. The results reported here should be considered to be initial results because tumors from only 15 patients were studied: 5 each from LCC, LCNEC and LCCNM. This was due to the rarity of these specific diseases.

  19. 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.

  20. 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.

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2011-11-01

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

  3. 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.

  4. 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

  5. Identification of two novel functional p53 responsive elements in the herpes simplex virus-1 genome.

    Science.gov (United States)

    Hsieh, Jui-Cheng; Kuta, Ryan; Armour, Courtney R; Boehmer, Paul E

    2014-07-01

    Analysis of the herpes simplex virus-1 (HSV-1) genome reveals two candidate p53 responsive elements (p53RE), located in proximity to the replication origins oriL and oriS, referred to as p53RE-L and p53RE-S, respectively. The sequences of p53RE-L and p53RE-S conform to the p53 consensus site and are present in HSV-1 strains KOS, 17, and F. p53 binds to both elements in vitro and in virus-infected cells. Both p53RE-L and p53RE-S are capable of conferring p53-dependent transcriptional activation onto a heterologous reporter gene. Importantly, expression of the essential immediate early viral transactivator ICP4 and the essential DNA replication protein ICP8, that are adjacent to p53RE-S and p53RE-L, are repressed in a p53-dependent manner. Taken together, this study identifies two novel functional p53RE in the HSV-1 genome and suggests a complex mechanism of viral gene regulation by p53 which may determine progression of the lytic viral replication cycle or the establishment of latency. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. 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

  7. 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....

  8. 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

  9. Assessment of the potential diagnostic value of serum p53 antibody for cancer: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    Full Text Available BACKGROUND: Mutant p53 protein over-expression has been reported to induce serum antibodies against p53. We assessed the diagnostic precision of serum p53 (s-p53 antibodies for diagnosis of cancer patients and compared the positive rates of the s-p53 antibody in different types of cancers. METHODS: We systematically searched PubMed and Embase, through May 31, 2012. Studies were assessed for quality using QUADAS (quality assessment of studies of diagnostic accuracy. The positive likelihood ratio (PLR and negative likelihood ratio (NLR were pooled separately and compared with overall accuracy measures using diagnostic odds ratios (DORs and Area under the curve(AUC. Meta regression and subgroup analyses were done, and heterogeneity and publication bias were assessed. RESULTS: Of 1089 studies initially identified, 100 eligible studies with 23 different types of tumor met the inclusion criteria for the meta-analysis (cases = 15953, controls = 8694. However, we could conduct independent meta analysis on only 13 of 36 types of tumors. Approximately 56% (56/100 of the included studies were of high quality (QUADAS score≥8. The summary estimates for quantitative analysis of serum p53 antibody in the diagnosis of cancers were: PLR 5.75 (95% CI: 4.60-7.19, NLR 0.81 (95%CI: 0.79-0.83 and DOR 7.56 (95% CI: 6.02-9.50. However, for the 13 types of cancers on which meta-analysis was conducted, the ranges for PLR (2.33-11.05, NLR (0.74-0.97, DOR (2.86-13.80, AUC(0.29-0.81, and positive rate (4.47%-28.36% indicated significant heterogeneity. We found that breast, colorectal, esophageal, gastric, hepatic, lymphoma, lung and ovarian cancer had relatively reasonable diagnostic accuracy. The remaining results of the five types of cancers suggested that s-p53 antibody had limited value. CONCLUSIONS: The current evidence suggests that s-p53 antibody has potential diagnostic value for cancer, especially for breast, colorectal, esophageal, gastric, hepatic

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

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    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

  11. Heterogeneous Biomedical Database Integration Using a Hybrid Strategy: A p53 Cancer Research Database

    Directory of Open Access Journals (Sweden)

    Vadim Y. Bichutskiy

    2006-01-01

    Full Text Available Complex problems in life science research give rise to multidisciplinary collaboration, and hence, to the need for heterogeneous database integration. The tumor suppressor p53 is mutated in close to 50% of human cancers, and a small drug-like molecule with the ability to restore native function to cancerous p53 mutants is a long-held medical goal of cancer treatment. The Cancer Research DataBase (CRDB was designed in support of a project to find such small molecules. As a cancer informatics project, the CRDB involved small molecule data, computational docking results, functional assays, and protein structure data. As an example of the hybrid strategy for data integration, it combined the mediation and data warehousing approaches. This paper uses the CRDB to illustrate the hybrid strategy as a viable approach to heterogeneous data integration in biomedicine, and provides a design method for those considering similar systems. More efficient data sharing implies increased productivity, and, hopefully, improved chances of success in cancer research. (Code and database schemas are freely downloadable, http://www.igb.uci.edu/research/research.html.

  12. 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

  13. Cytogenetic damage, oncogenic transformation and p53 induction in human epithelial cells in response to irradiation

    Science.gov (United States)

    Armitage, Mark

    Ionizing radiation can have several different effects on cells, some are almost instantaneous such as the generation of DNA damage, other cellular responses take a matter of minutes or hours - DNA repair protein induction/activation, and others may take months or even years to be manifested - carcinogenesis. Human epithelial cell lines derived from both normal, non-neoplastic tissues and from a malignant source were cultured in order to examine several effects of ionizing radiation on such cell types. Cells not from a malignant source were previously immortalized by viral infection or by transfection with viral sequences. Simian virus 40 immortalised uroepithelial cells (SV-HUC) were found to be approximately a factor of two fold more radioresistant than cells of malignant origin (T24) in terms of unrepaired clastogenic damage i.e. assessment of micronuclei levels following irradiation. SV-HUC lines unlike T24 cells are non-tumourigenic when inoculated into nude athymic mice. SV-HUC lines proved very resistant to full oncogenic transformation using radiation and chemical carcinogens. However, morphological alterations and decreased anchorage dependant growth was observed in post carcinogen treated cells after appropriate cell culture conditions were utilized. The progression from this phenotype to a fully tumourigenic one was not recorded in this study. The ability of ionizing radiation to induce increased levels of the nuclear phosphoprotein p53 was also assessed using several different cell lines. SV- HUC and T24 cell lines failed to exhibit any increased p53 stabilization following irradiation. One cell line, a human papilloma virus transformed line (HPV) did show an approximate two fold increase of the wild type p53 protein after treatment with radiation. Only the cell line HPV showed any cell cycle delay, resulting in accumulation of cells in the G2/M compartment in post irradiation cell cycle analysis. The status of p53 was also assessed i.e. wild type or

  14. Effect of radiation combined with p53 gene therapy and endostatin on mouse prostate cancer

    International Nuclear Information System (INIS)

    Zhang Min; Ren Jun; Xu Bo; Gao Xianshu; He Zhisong; He Xiaoming; Zhang Ming; Liu Chaoxing; He Xinyong; Cao Guangming; Zhang Shaolong

    2009-01-01

    Objective: To test the hypothesis that p53 gene therapy combined with endostatin can enhance tumor response to radiation therapy of RM-1 mouse xenograft prostate cancer and to investigate its mechanism. Methods: A mouse prostate cancer model was established. Then mice with xenograft tumor were randomly divided into group A (control), B (radiation), C (radiation and rAdp53), D (radiation and rh-endostatin) and E (radiation and rAdp53 and rhendostatin). On day 1, rAdp53 was injected intra-tumorously with 1 x 10 10 vp per animal to group C and E. From day 1 to 14, rh-endostatin was given 15 mg/kg intraperitoneally daily to group D and E. On day 4 single fraction of 15 Gy was given to tumors in groups B, C, D and E. Normal saline was injected intra-tumorously or intraperitoneaUy accordingly as control. No treatment was done to group A. Tumor volume was measured daily. Samples were collected on Days 5, 10 and 15. Ki67, CD31, p53 and VEGF were detected by means of immunohistochemistry. Results: (1) Radiation alone, radiation combined with intra-tumorous injection of Adp53 and/or intraperitoneal injection of rhendostatin resulted in tumor growth arrest of RM-1 cells in vivo (P = 0.000). Radiation combined with both rAdp53 and rhendostatin was the most effective treatment (P < 0.05). (2) All the four treatment groups had a decreased expression of mutant type P53 (P = 0.000). The expression of Ki67 in groups B and C were equal (P 0.05) and increasing (P = 0.000), respectively. Group D had a up-down-up curve (P < 0.05), but group E had a up-down one. On day 5 the expresion of VEGF in group E was the lowest (P < 0.05). An increased expression of MVD compared with the control was shown, and MVD in groups C, D and E were always higher than that in the control (P < 0.05). Conclusions: The limitation of radiotherapy could be overcome by combination with beth p53 gene therapy and endostatin on the growth of mouse prostate cancer cell. Radiation, rAdp53 and endostatin have their

  15. Characterisation of the p53 pathway in cell lines established from TH-MYCN transgenic mouse tumours.

    Science.gov (United States)

    Chen, Lindi; Esfandiari, Arman; Reaves, William; Vu, Annette; Hogarty, Michael D; Lunec, John; Tweddle, Deborah A

    2018-03-01

    Cell lines established from the TH-MYCN transgenic murine model of neuroblastoma are a valuable preclinical, immunocompetent, syngeneic model of neuroblastoma, for which knowledge of their p53 pathway status is important. In this study, the Trp53 status and functional response to Nutlin-3 and ionising radiation (IR) were determined in 6 adherent TH-MYCN transgenic cell lines using Sanger sequencing, western blot analysis and flow cytometry. Sensitivity to structurally diverse MDM2 inhibitors (Nutlin-3, MI-63, RG7388 and NDD0005) was determined using XTT proliferation assays. In total, 2/6 cell lines were Trp53 homozygous mutant (NHO2A and 844MYCN+/+) and 1/6 (282MYCN+/-) was Trp53 heterozygous mutant. For 1/6 cell lines (NHO2A), DNA from the corresponding primary tumour was found to be Trp53 wt. In all cases, the presence of a mutation was consistent with aberrant p53 signalling in response to Nutlin-3 and IR. In comparison to TP53 wt human neuroblastoma cells, Trp53 wt murine control and TH-MYCN cell lines were significantly less sensitive to growth inhibition mediated by MI-63 and RG7388. These murine Trp53 wt and mutant TH-MYCN cell lines are useful syngeneic, immunocompetent neuroblastoma models, the former to test p53-dependent therapies in combination with immunotherapies, such as anti-GD2, and the latter as models of chemoresistant relapsed neuroblastoma when aberrations in the p53 pathway are more common. The spontaneous development of Trp53 mutations in 3 cell lines from TH-MYCN mice may have arisen from MYCN oncogenic driven and/or ex vivo selection. The identified species-dependent selectivity of MI-63 and RG7388 should be considered when interpreting in vivo toxicity studies of MDM2 inhibitors.

  16. 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 ...

  17. 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

  18. Combined use of nuclear phosphoprotein c-Myc and cellular phosphoprotein p53 for hepatocellular carcinoma detection in high-risk chronic hepatitis C patients.

    Science.gov (United States)

    Attallah, A M; El-Far, M; Abdelrazek, M A; Omran, M M; Attallah, A A; Elkhouly, A A; Elkenawy, H M; Farid, K

    2017-10-01

    Hepatocellular carcinoma (HCC) is a multistage process resulting from various genetic changes. We aimed to determine nuclear phosphoprotein c-Myc and cellular phosphoprotein p53 expression and to evaluate their importance in HCC diagnosis. One hundred and twenty chronic hepatitis C (CHC) patients (60 non-HCC CHC patients and 60 HCC patients who had a single small (c-Myc and p53 were identified in liver tissues and serum samples using immunostaining, western blot and ELISA. Immunohistochemical detection of c-Myc and p53 with monospecific antibodies revealed intense and diffuse cytoplasmic staining patterns. Accumulated mutant proteins, released from tumour cells into the extracellular serum, were detected at 62 KDa, for c-Myc, and 53 KDa, for p53, using western blotting. In contrast to alpha feto-protein, there was a significant increase (p c-Myc (86.7% vs. 6.7%) and p53 (78.3% vs. 8.3%) in the malignant vs. non-malignant patients. The parallel combination of c-Myc and p53 reach the absolute sensitivity (100%), for more accurate and reliable HCC detection (specificity was 87%). c-Myc and p53 are potential HCC diagnostic biomarkers, and convenient combinations of them could improve diagnostic accuracy of HCC.

  19. 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.

  20. 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)

  1. 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

  2. Characterization of tumorigenicity and radio-sensitivity markers by an ex vivo approach. In vivo identification of p53 dependent radio-sensitivity markers

    International Nuclear Information System (INIS)

    Alvarez, S.

    2003-12-01

    After a detailed discussion of the relationship between cancer and genetic instability, of the structure, activation mechanisms, activity and biological functions of the p53 protein, a presentation of p53 mutants, and a recall of the effects of ionizing radiations, the author reports a biology research during which he investigated a cell model established from rat embryo lungs treated with Benzo[a]pyrene and made of tumoral lines muted by the p53 gene. He tried to identify markers which could report differences of tumorigenicity and radio-sensitivity observed in these different lines. He also tried to characterize radio-sensitivity molecular markers dependent on the p53 gene in a context of normal cells

  3. 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

  4. Knockdown of p53 suppresses Nanog expression in embryonic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdelalim, Essam Mohamed, E-mail: emohamed@qf.org.qa [Qatar Biomedical Research Institute, Qatar Foundation, Doha 5825 (Qatar); Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Department of Cytology and Histology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia (Egypt); Tooyama, Ikuo [Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan)

    2014-01-10

    Highlights: •We investigate the role of p53 in ESCs in the absence of DNA damage. •p53 knockdown suppresses ESC proliferation. •p53 knockdown downregulates Nanog expression. •p53 is essential for mouse ESC self-renewal. -- Abstract: Mouse embryonic stem cells (ESCs) express high levels of cytoplasmic p53. Exposure of mouse ESCs to DNA damage leads to activation of p53, inducing Nanog suppression. In contrast to earlier studies, we recently reported that chemical inhibition of p53 suppresses ESC proliferation. Here, we confirm that p53 signaling is involved in the maintenance of mouse ESC self-renewal. RNA interference-mediated knockdown of p53 induced downregulation of p21 and defects in ESC proliferation. Furthermore, p53 knockdown resulted in a significant downregulation in Nanog expression at 24 and 48 h post-transfection. p53 knockdown also caused a reduction in Oct4 expression at 48 h post-transfection. Conversely, exposure of ESCs to DNA damage caused a higher reduction of Nanog expression in control siRNA-treated cells than in p53 siRNA-treated cells. These data show that in the absence of DNA damage, p53 is required for the maintenance of mouse ESC self-renewal by regulating Nanog expression.

  5. 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

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

    Directory of Open Access Journals (Sweden)

    Harish Chander

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

  7. Dysfunctional p53 deletion mutants in cell lines derived from Hodgkin's lymphoma

    DEFF Research Database (Denmark)

    Feuerborn, Alexander; Moritz, Constanze; von Bonin, Frederike

    2006-01-01

    Classical Hodgkin's lymphoma (cHL) is a distinct malignancy of the immune system. Despite the progress made in the understanding of the pathology of cHL, the transforming events remain to be elucidated. It has been proposed that mutations in the TP53 gene in biopsy material as well as cell lines ...

  8. Binding of mutant and wild type p53 proteins to supercoiled DNA

    Czech Academy of Sciences Publication Activity Database

    Brázdová, Marie; Němcová, Kateřina; Pivoňková, Hana; Walter, K.; Warnecke, Gabriele; Živanovic, Marko; Krstic, Dušan; Paleček, Emil; Deppert, W.; Fojta, Miroslav

    2005-01-01

    Roč. 3, č. 1 (2005), S4-S5 ISSN 1214-021X. [Cells VI - Biological Days /18./. 24.10.2005-26.10.2005, České Budějovice] R&D Projects: GA MŠk(CZ) 1K04119; GA ČR(CZ) GA301/05/0416 Institutional research plan: CEZ:AV0Z50040507 Keywords : wtp53 * hot spot mutp53 * SCS binding Subject RIV: BO - Biophysics

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-10-02

    p53 protein plays a central role in suppressing tumorigenesis by inducing cell cycle arrest or apoptosis through transcription-dependent and -independent mechanisms. Emerging publications suggest that following stress, a fraction of p53 translocates to mitochondria to induce cytochrome c release and apoptosis. However, the localization of p53 under unstressed conditions remains largely unexplored. Here we show that p53 is localized at mitochondria in absence of apoptotic stimuli, when cells are proliferating, localization observed in various cell types (rodent and human). This is also supported by acellular assays in which p53 bind strongly to mitochondria isolated from rat liver. Furthermore, the mitochondria subfractionation study and the alkaline treatment of the mitochondrial p53 revealed that the majority of mitochondrial p53 is present in the membranous compartments. Finally, we identified VDAC, a protein of the mitochondrial outer-membrane, as a putative partner of p53 in unstressed/proliferative cells.

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

    International Nuclear Information System (INIS)

    Ferecatu, Ioana; Bergeaud, Marie; Rodriguez-Enfedaque, Aida; Le Floch, Nathalie; Oliver, Lisa; Rincheval, Vincent; Renaud, Flore; Vallette, Francois M.; Mignotte, Bernard; Vayssiere, Jean-Luc

    2009-01-01

    p53 protein plays a central role in suppressing tumorigenesis by inducing cell cycle arrest or apoptosis through transcription-dependent and -independent mechanisms. Emerging publications suggest that following stress, a fraction of p53 translocates to mitochondria to induce cytochrome c release and apoptosis. However, the localization of p53 under unstressed conditions remains largely unexplored. Here we show that p53 is localized at mitochondria in absence of apoptotic stimuli, when cells are proliferating, localization observed in various cell types (rodent and human). This is also supported by acellular assays in which p53 bind strongly to mitochondria isolated from rat liver. Furthermore, the mitochondria subfractionation study and the alkaline treatment of the mitochondrial p53 revealed that the majority of mitochondrial p53 is present in the membranous compartments. Finally, we identified VDAC, a protein of the mitochondrial outer-membrane, as a putative partner of p53 in unstressed/proliferative cells.

  11. Interplay between PTB and miR-1285 at the p53 3′UTR modulates the levels of p53 and its isoform Δ40p53α

    Science.gov (United States)

    Katoch, Aanchal; George, Biju; Iyyappan, Amrutha; Khan, Debjit

    2017-01-01

    Abstract p53 and its translational isoform Δ40p53 are involved in many important cellular functions like cell cycle, cell proliferation, differentiation and metabolism. Expression of both the isoforms can be regulated at different steps. In this study, we explored the role of 3′UTR in regulating the expression of these two translational isoforms. We report that the trans acting factor, Polypyrimidine Tract Binding protein (PTB), also interacts specifically with 3′UTR of p53 mRNA and positively regulates expression of p53 isoforms. Our results suggest that there is interplay between miRNAs and PTB at the 3′UTR under normal and stress conditions like DNA damage. Interestingly, PTB showed some overlapping binding regions in the p53 3′UTR with miR-1285. In fact, knockdown of miR-1285 as well as expression of p53 3′UTR with mutated miR-1285 binding sites resulted in enhanced association of PTB with the 3′UTR, which provides mechanistic insights of this interplay. Taken together, the results provide a plausible molecular basis of how the interplay between miRNAs and the PTB protein at the 3′UTR can play pivotal role in fine tuning the expression of the two p53 isoforms. PMID:28973454

  12. Downregulated long non-coding RNA MEG3 in breast cancer regulates proliferation, migration and invasion by depending on p53’s transcriptional activity

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Lin [West Biostatistics and Cost-effectiveness Research Center, Medical Insurance Office, West China Hospital of Sichuan University, 610041, Sichuan (China); Li, Yu [Department of Anesthesiology, West China Hospital, Sichuan University, 610041, Sichuan (China); Yang, Bangxiang, E-mail: b19933009@qq.coom [Department of Pain Management, West China Hospital of Sichuan University, 610041, Sichuan (China)

    2016-09-09

    Long non-coding RNAs (lncRNAs) was found to play critical roles in tumorigenesis, hence, screen of tumor-related lncRNAs, identification of their biological roles is important for understanding the processes of tumorigenesis. In this study, we identified the expressing difference of several tumor-related lncRNAs in breast cancer samples and found that, MEG3, which is downregulated in non-small cell lung cancer (NSCLC) tumor tissues, is also downregulated in breast cancer samples compared with adjacent tissues. For figuring out the effect of MEG3 in breast cancer cells MCF7 and MB231, we overexpressed MEG3 in these cells, and found that it resulted the inhibition of proliferation, colony formation, migration and invasion capacities by enhancing p53’s transcriptional activity on its target genes, including p21, Maspin and KAI1. MEG3 presented similar effects in MB157, which is a p53-null breast cancer cell line, when functional p53 but not p53R273H mutant, which lacks transcriptional activity, was introduced. Surprisingly, overexpression of MEG3 activates p53’s transcriptional activity by decreasing MDM2’s transcription level, and thus stabilizes and accumulates P53. Taken together, our findings indicate that MEG3 is downregulated in breast cancer tissues and affects breast cancer cells’ malignant behaviors, which indicate MEG3 a potential therapeutic target for breast cancer. - Highlights: • MEG3 RNA is widely downregulated in breast tumor tissue. • MEG3 regulates P53 indirectly through transcriptional regulation of MDM2. • Under unstressed condition, MEG3-related P53 accumulation transcriptionally activates p53’s target genes. • MEG3 expression level tightly regulates proliferation, colony formation, migration and invasion in breast tumor cells.

  13. 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.

  14. 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

  15. Neem oil limonoids induces p53-independent apoptosis and autophagy.

    Science.gov (United States)

    Srivastava, Pragya; Yadav, Neelu; Lella, Ravi; Schneider, Andrea; Jones, Anthony; Marlowe, Timothy; Lovett, Gabrielle; O'Loughlin, Kieran; Minderman, Hans; Gogada, Raghu; Chandra, Dhyan

    2012-11-01

    Azadirachta indica, commonly known as neem, has a wide range of medicinal properties. Neem extracts and its purified products have been examined for induction of apoptosis in multiple cancer cell types; however, its underlying mechanisms remain undefined. We show that neem oil (i.e., neem), which contains majority of neem limonoids including azadirachtin, induced apoptotic and autophagic cell death. Gene silencing demonstrated that caspase cascade was initiated by the activation of caspase-9, whereas caspase-8 was also activated late during neem-induced apoptosis. Pretreatment of cancer cells with pan caspase inhibitor, z-VAD inhibited activities of both initiator caspases (e.g., caspase-8 and -9) and executioner caspase-3. Neem induced the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria, suggesting the involvement of both caspase-dependent and AIF-mediated apoptosis. p21 deficiency caused an increase in caspase activities at lower doses of neem, whereas p53 deficiency did not modulate neem-induced caspase activation. Additionally, neem treatment resulted in the accumulation of LC3-II in cancer cells, suggesting the involvement of autophagy in neem-induced cancer cell death. Low doses of autophagy inhibitors (i.e., 3-methyladenine and LY294002) did not prevent accumulation of neem-induced LC3-II in cancer cells. Silencing of ATG5 or Beclin-1 further enhanced neem-induced cell death. Phosphoinositide 3-kinase (PI3K) or autophagy inhibitors increased neem-induced caspase-3 activation and inhibition of caspases enhanced neem-induced autophagy. Together, for the first time, we demonstrate that neem induces caspase-dependent and AIF-mediated apoptosis, and autophagy in cancer cells.

  16. Neem oil limonoids induces p53-independent apoptosis and autophagy

    Science.gov (United States)

    Chandra, Dhyan

    2012-01-01

    Azadirachta indica, commonly known as neem, has a wide range of medicinal properties. Neem extracts and its purified products have been examined for induction of apoptosis in multiple cancer cell types; however, its underlying mechanisms remain undefined. We show that neem oil (i.e., neem), which contains majority of neem limonoids including azadirachtin, induced apoptotic and autophagic cell death. Gene silencing demonstrated that caspase cascade was initiated by the activation of caspase-9, whereas caspase-8 was also activated late during neem-induced apoptosis. Pretreatment of cancer cells with pan caspase inhibitor, z-VAD inhibited activities of both initiator caspases (e.g., caspase-8 and -9) and executioner caspase-3. Neem induced the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria, suggesting the involvement of both caspase-dependent and AIF-mediated apoptosis. p21 deficiency caused an increase in caspase activities at lower doses of neem, whereas p53 deficiency did not modulate neem-induced caspase activation. Additionally, neem treatment resulted in the accumulation of LC3-II in cancer cells, suggesting the involvement of autophagy in neem-induced cancer cell death. Low doses of autophagy inhibitors (i.e., 3-methyladenine and LY294002) did not prevent accumulation of neem-induced LC3-II in cancer cells. Silencing of ATG5 or Beclin-1 further enhanced neem-induced cell death. Phosphoinositide 3-kinase (PI3K) or autophagy inhibitors increased neem-induced caspase-3 activation and inhibition of caspases enhanced neem-induced autophagy. Together, for the first time, we demonstrate that neem induces caspase-dependent and AIF-mediated apoptosis, and autophagy in cancer cells. PMID:22915764

  17. Structural Basis of Competitive Recognition of p53 and MDM2 by HAUSP/USP7: Implications for the Regulation of the p53-MDM2 Pathway.

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Herpesvirus-associated ubiquitin-specific protease (HAUSP, also known as USP7, a deubiquitylating enzyme of the ubiquitin-specific processing protease family, specifically deubiquitylates both p53 and MDM2, hence playing an important yet enigmatic role in the p53-MDM2 pathway. Here we demonstrate that both p53 and MDM2 specifically recognize the N-terminal tumor necrosis factor-receptor associated factor (TRAF-like domain of HAUSP in a mutually exclusive manner. HAUSP preferentially forms a stable HAUSP-MDM2 complex even in the presence of excess p53. The HAUSP-binding elements were mapped to a peptide fragment in the carboxy-terminus of p53 and to a short-peptide region preceding the acidic domain of MDM2. The crystal structures of the HAUSP TRAF-like domain in complex with p53 and MDM2 peptides, determined at 2.3-A and 1.7-A resolutions, respectively, reveal that the MDM2 peptide recognizes the same surface groove in HAUSP as that recognized by p53 but mediates more extensive interactions. Structural comparison led to the identification of a consensus peptide-recognition sequence by HAUSP. These results, together with the structure of a combined substrate-binding-and-deubiquitylation domain of HAUSP, provide important insights into regulation of the p53-MDM2 pathway by HAUSP.

  18. 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.

  19. 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 ...

  20. Phosphorylation and nuclear accumulation are distinct events contributing to the activation of p53

    International Nuclear Information System (INIS)

    O'Hagan, Heather M.; Ljungman, Mats

    2004-01-01

    It has been recently shown that ionizing radiation (IR) and the mRNA synthesis inhibitor 5,6-dichloro-1-b-D-ribofuranosylbenzimidazole (DRB) act in synergy to induce p53-mediated transactivation of reporter plasmids in human cells [Oncogene 19 (2000) 3829]. We have extended these studies and show that ionizing radiation and DRB also act in synergy to induce ATM-mediated phosphorylation of the ser15 site of p53 and enhance the expression of endogenous p21 protein. Examination of the localization of p53 revealed that while DRB did not induce phosphorylation of the ser15 site of p53 but efficiently accumulated p53 in the nucleus, ionizing radiation induced phosphorylation of the ser15 site of p53 without prolonged nuclear accumulation. Importantly, the combination of DRB and IR resulted in a strong accumulation of phosphorylated p53 in the nucleus that was more persistent then p53 accumulation after IR alone. Furthermore, the nuclear export inhibitor leptomycin B showed a similar synergy with IR as did DRB regarding ser15 phosphorylation of p53 and p21 induction. These results suggest that the synergistic activation of the p53 response by the combination treatment is due to the activation of two distinct pathways where DRB causes the prolonged nuclear accumulation of p53 while ionizing radiation activates p53 by ATM-mediated phosphorylation

  1. Isolation and characterization of DUSP11, a novel p53 target gene

    DEFF Research Database (Denmark)

    Caprara, Greta; Zamponi, Raffaella; Melixetian, Marina

    2009-01-01

    target gene. Consistent with this, the expression of DUSP11 is induced in a p53-dependent manner after treatment with DNA damaging agents. Chromatin immunoprecipitation analysis showed that p53 binds to 2 putative p53 DNA binding sites in the promoter region of DUSP11. Colony formation and proliferation...

  2. 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

  3. Hypoxia-induced p53 modulates both apoptosis and radiosensitivity via AKT

    NARCIS (Netherlands)

    Leszczynska, K.B.; Foskolou, I.P.; Abraham, A.G.; Anbalagan, S.; Tellier, C.; Haider, S.; Span, P.N.; O'Neill, E.E.; Buffa, F.M.; Hammond, E.M.

    2015-01-01

    Restoration of hypoxia-induced apoptosis in tumors harboring p53 mutations has been proposed as a potential therapeutic strategy; however, the transcriptional targets that mediate hypoxia-induced p53-dependent apoptosis remain elusive. Here, we demonstrated that hypoxia-induced p53-dependent

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

    NARCIS (Netherlands)

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

    2004-01-01

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

  5. RITA can induce cell death in p53-defective cells independently of p53 function via activation of JNK/SAPK and p38.

    Science.gov (United States)

    Weilbacher, A; Gutekunst, M; Oren, M; Aulitzky, W E; van der Kuip, H

    2014-07-10

    Significant advances have been made in the development of small molecules blocking the p53/MDM2 interaction. The Mdm2 inhibitor Nutlin-3 is restricted to tumors carrying wtp53. In contrast, RITA, a compound that binds p53, has recently been shown also to restore transcriptional functions of mtp53. As more than 50% of solid tumors carry p53 mutations, RITA promises to be a more effective therapeutic strategy than Nutlin-3. We investigated effects of RITA on apoptosis, cell cycle and induction of 45 p53 target genes in a panel of 14 cell lines from different tumor entities with different p53 status as well as primary lymphocytes and fibroblasts. Nine cell strains expressed wtp53, four harbored mtp53, and three were characterized by the loss of p53 protein. A significant induction of cell death upon RITA was observed in 7 of 16 cell lines. The nonmalignant cells in our panel were substantially less sensitive. We found that in contrast to Nultin-3, RITA is capable to induce cell death not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells. Importantly, whereas p53 has a central role for RITA-mediated effects in wtp53 cells, neither p53 nor p63 or p73 were essential for the RITA response in mtp53 or p53-null cells in our panel demonstrating that besides the known p53-dependent action of RITA in wtp53 cells, RITA can induce cell death also independently of p53 in cells harboring defective p53. We identified an important role of both p38 and JNK/SAPK for sensitivity to RITA in these cells leading to a typical caspase- and BAX/BAK-dependent mitochondrial apoptosis. In conclusion, our data demonstrate that RITA can induce apoptosis through p38 and JNK/SAPK not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells, making RITA an interesting tumor-selective drug.

  6. Inhibition of autophagy exerts anti-colon cancer effects via apoptosis induced by p53 activation and ER stress

    International Nuclear Information System (INIS)

    Sakitani, Kosuke; Hirata, Yoshihiro; Hikiba, Yohko; Hayakawa, Yoku; Ihara, Sozaburo; Suzuki, Hirobumi; Suzuki, Nobumi; Serizawa, Takako; Kinoshita, Hiroto; Sakamoto, Kei; Nakagawa, Hayato; Tateishi, Keisuke; Maeda, Shin; Ikenoue, Tsuneo; Kawazu, Shoji; Koike, Kazuhiko

    2015-01-01

    Although some molecularly targeted drugs for colorectal cancer are used clinically and contribute to a better prognosis, the current median survival of advanced colorectal cancer patients is not sufficient. Autophagy, a basic cell survival mechanism mediated by recycling of cellular amino acids, plays an important role in cancer. Recently, autophagy has been highlighted as a promising new molecular target. The unfolded protein response (UPR) reportedly act in complementary fashion with autophagy in intestinal homeostasis. However, the roles of UPR in colon cancer under autophagic inhibition remain to be elucidated. We aim to clarify the inhibitory effect of autophagy on colon cancer. We crossed K19 CreERT and Atg5 flox/flox mice to generate Atg5 flox/flox /K19 CreERT mice. Atg5 flox/flox /K19 CreERT mice were first treated with azoxymethane/dextran sodium sulfate and then injected with tamoxifen to inhibit autophagy in CK19-positive epithelial cells. To examine the anti-cancer mechanisms of autophagic inhibition, we used colon cancer cell lines harboring different p53 gene statuses, as well as small interfering RNAs (siRNAs) targeting Atg5 and immunoglobulin heavy-chain binding protein (BiP), a chaperone to aid folding of unfolded proteins. Colon tumors in Atg5 flox/flox /K19 CreERT mice showed loss of autophagic activity and decreased tumor size (the total tumor diameter was 28.1 mm in the control and 20.7 mm in Atg5 flox/flox /K19 CreERT mice, p = 0.036). We found that p53 and UPR/endoplasmic reticulum (ER) stress-related proteins, such as cleaved caspase 3, and CAAT/enhancer-binding protein homologous protein, are up-regulated in colon tumors of Atg5 flox/flox /K19 CreERT mice. Although Atg5 and BiP silencing, respectively, increased apoptosis in p53 wild type cells, Atg5 silencing alone did not show the same effect on apoptosis in p53 mutant cells. However, co-transfection of Atg5 and BiP siRNAs led to increased apoptosis in p53 mutant cells. Blocking autophagy

  7. 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

  8. 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.

  9. 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.

  10. Transactivation domain of p53 regulates DNA repair and integrity in human iPS cells.

    Science.gov (United States)

    Kannappan, Ramaswamy; Mattapally, Saidulu; Wagle, Pooja A; Zhang, Jianyi

    2018-05-18

    The role of p53 transactivation domain (p53-TAD), a multifunctional and dynamic domain, on DNA repair and retaining DNA integrity in human iPS cells has never been studied. p53-TAD was knocked out in iPS cells using CRISPR/Cas9 and was confirmed by DNA sequencing. p53-TAD KO cells were characterized by: accelerated proliferation, decreased population doubling time, and unaltered Bcl2, BBC3, IGF1R, Bax and altered Mdm2, p21, and PIDD transcripts expression. In p53-TAD KO cells p53 regulated DNA repair proteins XPA, DNA polH and DDB2 expression were found to be reduced compared to p53-WT cells. Exposure to low dose of doxorubicin (Doxo) induced similar DNA damage and DNA damage response (DDR) measured by RAD50 and MRE11 expression, Checkpoint kinase 2 activation and γH2A.X recruitment at DNA strand breaks in both the cell groups indicating silencing p53-TAD do not affect DDR mechanism upstream of p53. Following removal of Doxo p53-WT hiPS cells underwent DNA repair, corrected their damaged DNA and restored DNA integrity. Conversely, p53-TAD KO hiPS cells did not undergo complete DNA repair and failed to restore DNA integrity. More importantly continuous culture of p53-TAD KO hiPS cells underwent G2/M cell cycle arrest and expressed cellular senescent marker p16 INK4a . Our data clearly shows that silencing transactivation domain of p53 did not affect DDR but affected the DNA repair process implying the crucial role of p53 transactivation domain in maintaining DNA integrity. Therefore, activating p53-TAD domain using small molecules may promote DNA repair and integrity of cells and prevent senescence.

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    based on CD1a positivity. The slides were stained with p53 antibody and semiquantitatively evaluated using a grading system from 1 to 5 as an estimate for 0% to 20%, 20% to 40%, 40% to 60%, 60% to 80%, and 80% to 100% p53-positive for pathologic Langerhans cells (pLC), respectively. RESULTS: The p53...... protein was expressed in various degrees in pLC in all lesions. The degree of p53 expression could not be correlated to either clinical manifestation or outcome. CONCLUSIONS: An increased expression of p53 in pLC indicates an altered DNA repair control with or without abnormal control of apoptosis....

  12. Stabilization and activation of p53 are regulated independently by different phosphorylation events

    Science.gov (United States)

    Chernov, Mikhail V.; Ramana, Chilakamarti V.; Adler, Victor V.; Stark, George R.

    1998-01-01

    Treatment of mouse or human cells with the protein kinase C (PKC) inhibitors H7 or bisindolylmaleimide I induced an increase in the lifetime of p53, leading to its accumulation. In inhibitor-treated cells, p53 translocated to the nuclei and bound to DNA but was not competent to induce transcription. However, transactivation could be induced by subsequent DNA damage. Phorbol ester, a potent activator of PKC, significantly inhibited the accumulation of p53 after DNA damage. Therefore, constitutive PKC-dependent phosphorylation of p53 itself, or of a protein that interacts with p53, is required for the rapid degradation of p53 in untreated cells. Furthermore, an increase in the lifetime of p53 is not accompanied necessarily by its activation. Treatment with the PKC inhibitors decreased the overall level of p53 phosphorylation but led to the appearance of a phosphopeptide not seen in tryptic digests of p53 from untreated cells. Therefore, the lifetime and activities of p53 are likely to be regulated by distinct alterations of the phosphorylation pattern of p53, probably caused by the actions of different kinases. PMID:9482877

  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. 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)

  16. 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)

  17. Loss of P53 Function in Colon Cancer Cells Results in Increased Phosphocholine and Total Choline

    Directory of Open Access Journals (Sweden)

    Noriko Mori

    2004-10-01

    Full Text Available Mutations in the p53 gene are the most frequently observed genetic lesions in human cancers. Human cancers that contain a p53 mutation are more aggressive, more apt to metastasize, and more often fatal. p53 controls numerous downstream targets that can influence various outcomes such as apoptosis, growth arrest, and DNA repair. Based on previous observations using 1H magnetic resonance spectroscopy (MRS, we have identified choline phospholipid metabolite intensities typical of increased malignancy. Here we have used 1H MRS to characterize the choline phospholipid metabolite levels of p53+/+ and p53−/– cells, and demonstrated that loss of p53 function results in increased phosphocholine and total choline. These data suggest that the increased malignancy of cancer cells resulting from loss of p53 may be mediated, in part, through the choline phospholipid pathway.

  18. Association of p53 protein expression with clinical outcome in advanced supraglottic cancer

    International Nuclear Information System (INIS)

    Kang, Jin Oh; Hong, Seong Eon

    1998-01-01

    To determine the incidence and prognostic effect of p53 expression in patients with advanced supraglottic cancer. Twenty-one cases of total 48 advanced supraglottic cancer patients who received postoperative adjuvant radiation therapy were evaluated by immunohistochemical staining employing p53 monoclonal antibody. Three out of six stage III patients and four out of fifteen stage IV patients showed p53 expression without statistically significant difference (p=0.608). Five year survival rates are 93% in p53 negative, 86% in p53 positive patients and there was no significant difference(p=0.776). p53 expression does not show statistically significant correlation with primary tumor status(p=0.877), lymph node status(p=0.874) and age(p=0.64). There was no statistically significant correlation between traditionally known risk factors and p53 expression

  19. Inhibition of Endothelial p53 Improves Metabolic Abnormalities Related to Dietary Obesity

    Directory of Open Access Journals (Sweden)

    Masataka Yokoyama

    2014-06-01

    Full Text Available Accumulating evidence has suggested a role for p53 activation in various age-associated conditions. Here, we identified a crucial role of endothelial p53 activation in the regulation of glucose homeostasis. Endothelial expression of p53 was markedly upregulated when mice were fed a high-calorie diet. Disruption of endothelial p53 activation improved dietary inactivation of endothelial nitric oxide synthase that upregulated the expression of peroxisome proliferator-activated receptor-γ coactivator-1α in skeletal muscle, thereby increasing mitochondrial biogenesis and oxygen consumption. Mice with endothelial cell-specific p53 deficiency fed a high-calorie diet showed improvement of insulin sensitivity and less fat accumulation, compared with control littermates. Conversely, upregulation of endothelial p53 caused metabolic abnormalities. These results indicate that inhibition of endothelial p53 could be a novel therapeutic target to block the vicious cycle of cardiovascular and metabolic abnormalities associated with obesity.

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

    International Nuclear Information System (INIS)

    Kim, In Ah; Choi, Ihl Bhong; Kang, Ki Mun; Jang, Ji Young; Kim, Kyung Mi; Park, Kyung Shin; Kim, Young Shin; Kang, Chang Suk; Cho, Seung Ho; Kim, Hyung Tae

    1999-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Ah; Choi, Ihl Bhong; Kang, Ki Mun; Jang, Ji Young; Kim, Kyung Mi; Park, Kyung Shin; Kim, Young Shin; Kang, Chang Suk; Cho, Seung Ho; Kim, Hyung Tae [College of Medicine, The Catholic Univ., Seoul (Korea, Republic of)

    1999-03-01

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

  2. Dopaminergic Neuron-Specific Deletion of p53 Gene Attenuates Methamphetamine Neurotoxicity.

    Science.gov (United States)

    Lu, Tao; Kim, Paul P; Greig, Nigel H; Luo, Yu

    2017-08-01

    p53 plays an essential role in the regulation of cell death in dopaminergic (DA) neurons and its activation has been implicated in the neurotoxic effects of methamphetamine (MA). However, how p53 mediates MA neurotoxicity remains largely unknown. In this study, we examined the effect of DA-specific p53 gene deletion in DAT-p53KO mice. Whereas in vivo MA binge exposure reduced locomotor activity in wild-type (WT) mice, this was significantly attenuated in DAT-p53KO mice and associated with significant differences in the levels of the p53 target genes BAX and p21 between WT and DAT-p53KO. Notably, DA-specific deletion of p53 provided protection of substantia nigra pars reticulata (SNpr) tyrosine hydroxylase (TH) positive fibers following binge MA, with DAT-p53KO mice having less decline of TH protein levels in striatum versus WT mice. Whereas DAT-p53KO mice demonstrated a consistently higher density of TH fibers in striatum compared to WT mice at 10 days after MA exposure, DA neuron counts within the substantia nigra pars compacta (SNpc) were similar. Finally, supportive of these results, administration of a p53-specific inhibitor (PFT-α) provided a similarly protective effect on MA binge-induced behavioral deficits. Neither DA specific p53 deletion nor p53 pharmacological inhibition affected hyperthermia induced by MA binge. These findings demonstrate a specific contribution of p53 activation in behavioral deficits and DA neuronal terminal loss by MA binge exposure.

  3. Gene expression and apoptosis induction in p53-heterozygous irradiated mice

    International Nuclear Information System (INIS)

    Di Masi, Alessandra; Antoccia, Antonio; Dimauro, Ivan; Argentino-Storino, Alberta; Mosiello, Alberto; Mango, Ruggiero; Novelli, Giuseppe; Tanzarella, Caterina

    2006-01-01

    The role of the p53-genetic background in the expression of genes involved in either cell cycle checkpoint activation or apoptosis was evaluated in p53+/+ and p53+/- mouse strains at both basal levels and after DNA-induced damage. The spleen, colon, kidneys, lungs and liver of both strains were harvested from untreated animals and from mice exposed to 7.5 Gy of X-rays and sacrificed after 5 h. No significant differences were observed in the basal levels of p53 protein, CDKN1A and bax mRNA and spontaneous apoptosis, neither among the different organs within the same strain, nor between the same organ in the p53+/+ and p53+/- strains. After X-ray exposure, p53-dependent regulation was strikingly tissue-specific. In wild-type irradiated mice, p53 protein level increased after radiation treatment in all the organs analysed, whereas both CDKN1A and bax genes transcription increased in the spleen, colon and lungs, as assessed by means of quantitative RT-PCR. In p53+/- irradiated mice, on the contrary, a significant p53 induction was detected only in the spleen, while CDKN1A and bax genes levels increased in the spleen, colon and lungs, revealing the existence of different mechanisms of gene regulation in different organs. Apoptosis induction was observed in the spleen and colon of both strains, even if to lower extent in p53+/- mice compared to p53+/+ animals. In conclusion, in the spleen and colon, target gene transcription and apoptosis may be related to p53 genotype after DNA damage-induction. Moreover, our findings highlight the selectivity of p53 in transactivation following DNA damage in vivo, resulting in tissue-specific responses

  4. Gene expression and apoptosis induction in p53-heterozygous irradiated mice

    Energy Technology Data Exchange (ETDEWEB)

    Di Masi, Alessandra [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy); Antoccia, Antonio [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy); Dimauro, Ivan [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy); Argentino-Storino, Alberta [Research Toxicology Centre S.p.A., Via Tito Speri, 18, 00040 Pomezia (RM) (Italy); Mosiello, Alberto [Research Toxicology Centre S.p.A., Via Tito Speri, 18, 00040 Pomezia (RM) (Italy); Mango, Ruggiero [Centre of Excellence for Genomic Risk Assessment in Multifactorial and Complex Diseases, School of Medicine, University of Rome ' Tor Vergata' , Rome (Italy); Novelli, Giuseppe [Centre of Excellence for Genomic Risk Assessment in Multifactorial and Complex Diseases, School of Medicine, University of Rome ' Tor Vergata' , Rome (Italy); Tanzarella, Caterina [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy)]. E-mail: tanzarel@uniroma3.it

    2006-02-22

    The role of the p53-genetic background in the expression of genes involved in either cell cycle checkpoint activation or apoptosis was evaluated in p53+/+ and p53+/- mouse strains at both basal levels and after DNA-induced damage. The spleen, colon, kidneys, lungs and liver of both strains were harvested from untreated animals and from mice exposed to 7.5 Gy of X-rays and sacrificed after 5 h. No significant differences were observed in the basal levels of p53 protein, CDKN1A and bax mRNA and spontaneous apoptosis, neither among the different organs within the same strain, nor between the same organ in the p53+/+ and p53+/- strains. After X-ray exposure, p53-dependent regulation was strikingly tissue-specific. In wild-type irradiated mice, p53 protein level increased after radiation treatment in all the organs analysed, whereas both CDKN1A and bax genes transcription increased in the spleen, colon and lungs, as assessed by means of quantitative RT-PCR. In p53+/- irradiated mice, on the contrary, a significant p53 induction was detected only in the spleen, while CDKN1A and bax genes levels increased in the spleen, colon and lungs, revealing the existence of different mechanisms of gene regulation in different organs. Apoptosis induction was observed in the spleen and colon of both strains, even if to lower extent in p53+/- mice compared to p53+/+ animals. In conclusion, in the spleen and colon, target gene transcription and apoptosis may be related to p53 genotype after DNA damage-induction. Moreover, our findings highlight the selectivity of p53 in transactivation following DNA damage in vivo, resulting in tissue-specific responses.

  5. FGF1 protects neuroblastoma SH-SY5Y cells from p53-dependent apoptosis through an intracrine pathway regulated by FGF1 phosphorylation

    Science.gov (United States)

    Pirou, Caroline; Montazer-Torbati, Fatemeh; Jah, Nadège; Delmas, Elisabeth; Lasbleiz, Christelle; Mignotte, Bernard; Renaud, Flore

    2017-01-01

    Neuroblastoma, a sympathetic nervous system tumor, accounts for 15% of cancer deaths in children. In contrast to most human tumors, p53 is rarely mutated in human primary neuroblastoma, suggesting impaired p53 activation in neuroblastoma. Various studies have shown correlations between fgf1 expression levels and both prognosis severity and tumor chemoresistance. As we previously showed that fibroblast growth factor 1 (FGF1) inhibited p53-dependent apoptosis in neuron-like PC12 cells, we initiated the study of the interaction between the FGF1 and p53 pathways in neuroblastoma. We focused on the activity of either extracellular FGF1 by adding recombinant rFGF1 in media, or of intracellular FGF1 by overexpression in human SH-SY5Y and mouse N2a neuroblastoma cell lines. In both cell lines, the genotoxic drug etoposide induced a classical mitochondrial p53-dependent apoptosis. FGF1 was able to inhibit p53-dependent apoptosis upstream of mitochondrial events in SH-SY5Y cells by both extracellular and intracellular pathways. Both rFGF1 addition and etoposide treatment increased fgf1 expression in SH-SY5Y cells. Conversely, rFGF1 or overexpressed FGF1 had no effect on p53-dependent apoptosis and fgf1 expression in neuroblastoma N2a cells. Using different FGF1 mutants (that is, FGF1K132E, FGF1S130A and FGF1S130D), we further showed that the C-terminal domain and phosphorylation of FGF1 regulate its intracrine anti-apoptotic activity in neuroblastoma SH-SY5Y cells. This study provides the first evidence for a role of an intracrine growth factor pathway on p53-dependent apoptosis in neuroblastoma, and could lead to the identification of key regulators involved in neuroblastoma tumor progression and chemoresistance. PMID:29048426

  6. Identification of a p53-response element in the promoter of the proline oxidase gene

    International Nuclear Information System (INIS)

    Maxwell, Steve A.; Kochevar, Gerald J.

    2008-01-01

    Proline oxidase (POX) is a p53-induced proapoptotic gene. We investigated whether p53 could bind directly to the POX gene promoter. Chromatin immunoprecipitation (ChIP) assays detected p53 bound to POX upstream gene sequences. In support of the ChIP results, sequence analysis of the POX gene and its 5' flanking sequences revealed a potential p53-binding site, GGGCTTGTCTTCGTGTGACTTCTGTCT, located at 1161 base pairs (bp) upstream of the transcriptional start site. A 711-bp DNA fragment containing the candidate p53-binding site exhibited reporter gene activity that was induced by p53. In contrast, the same DNA region lacking the candidate p53-binding site did not show significant p53-response activity. Electrophoretic mobility shift assay (EMSA) in ACHN renal carcinoma cell nuclear lysates confirmed that p53 could bind to the 711-bp POX DNA fragment. We concluded from these experiments that a p53-binding site is positioned at -1161 to -1188 bp upstream of the POX transcriptional start site

  7. p53-Induced Apoptosis Occurs in the Absence of p14ARF in Malignant Pleural Mesothelioma

    Directory of Open Access Journals (Sweden)

    Sally Hopkins-Donaldson

    2006-07-01

    Full Text Available Malignant pleural mesotheliomas (MPMs are usually wild type for the p53 gene but contain homozygous deletions in the INK4A locus that encodes p14ARF, an inhibitor of p53-MDM2 interaction. Previous findings suggest that lack of p14ARF expression and the presence of SV40 large T antigen (L-Tag result in p53 inactivation in MPM. We did not detect SV40 L-Tag mRNA in either MPM cell lines or primary cultures, treatment of p14ARF-deficient cells with cisplatin (CDDP increased both total and phosphorylated p53 and enhanced p53 DNA-binding activity. On incubation with CDDP, levels of positively regulated p53 transcriptional targets p21WAF, PIG3, MDM2, Bax, PUMA increased in p14ARF-deficient cells, whereas negatively regulated survivin decreased. Significantly, p53-induced apoptosis was activated by CDDP in p14ARF-deficient cells, treatment with p53-specific siRNA rendered them more CDDP-resistant. p53 was also activated by: 1 inhibition of MDM2 (using nutlin-3; 2 transient overexpression of p14ARF; and 3 targeting of survivin using antisense oligonucleotides. However, it is noteworthy that only survivin downregulation sensitized cells to CDDP-induced apoptosis. These results suggest that p53 is functional in the absence of p14ARF in MPM and that targeting of the downstream apoptosis inhibitor survivin can sensitize to CDDP-induced apoptosis.

  8. 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

  9. NGF-mediated transcriptional targets of p53 in PC12 neuronal differentiation

    Directory of Open Access Journals (Sweden)

    Labhart Paul

    2007-05-01

    Full Text Available Abstract Background p53 is recognized as a critical regulator of the cell cycle and apoptosis. Mounting evidence also suggests a role for p53 in differentiation of cells including neuronal precursors. We studied the transcriptional role of p53 during nerve growth factor-induced differentiation of the PC12 line into neuron-like cells. We hypothesized that p53 contributed to PC12 differentiation through the regulation of gene targets distinct from its known transcriptional targets for apoptosis or DNA repair. Results Using a genome-wide chromatin immunoprecipitation cloning technique, we identified and validated 14 novel p53-regulated genes following NGF treatment. The data show p53 protein was transcriptionally activated and contributed to NGF-mediated neurite outgrowth during differentiation of PC12 cells. Furthermore, we describe stimulus-specific regulation of a subset of these target genes by p53. The most salient differentiation-relevant target genes included wnt7b involved in dendritic extension and the tfcp2l4/grhl3 grainyhead homolog implicated in ectodermal development. Additional targets included brk, sdk2, sesn3, txnl2, dusp5, pon3, lect1, pkcbpb15 and other genes. Conclusion Within the PC12 neuronal context, putative p53-occupied genomic loci spanned the entire Rattus norvegicus genome upon NGF treatment. We conclude that receptor-mediated p53 transcriptional activity is involved in PC12 differentiation and may suggest a contributory role for p53 in neuronal development.

  10. Homologous recombination in mammalian cells: effect of p53 and Bcl-2 proteins, replication inhibition and ionizing radiations

    International Nuclear Information System (INIS)

    Saintigny, Yannick

    1999-01-01

    The control of cell cycle, associated with the mechanisms of replication, DNA repair/recombination allows the cells to maintain their genetic integrity. The p53 protein ensures the control of G1/S transition. Its inactivation would allow to initial replication on damaged matrix and lead to the block of replication forks followed by DNA strand breaks, good substrates for recombination. This work shows that the expression of mutant p53 protein stimulates both spontaneous and radio-induced homologous recombination, independently of the control of cell cycle. Moreover, the use of a set of replication inhibitors show that inhibition of the replication elongation stimulates recombination more strongly than the initiation inhibition. Replication arrest by these inhibitors also significantly increases the number of DNA strand breaks. These results highlighted a point of action of p53 protein on the ultimate stages of the homologous recombination mechanism. Lastly, the expression of Bcl-2 protein inhibits apoptosis and increases survival, but specifically inhibits conservative recombination, after radiation as well as in absence of apoptotic stress. The extinction of this mechanism of DNA repair is associated with an increase of mutagenesis. Taken together, these results allow ta consider the maintenance of the genetic stability as a cellular network involving different pathways. A multiple stages model for tumoral progression can be deduced. (author) [fr

  11. The Histone Lysine Demethylase JMJD3/KDM6B Is Recruited to p53 Bound Promoters and Enhancer Elements in a p53 Dependent Manner

    DEFF Research Database (Denmark)

    Williams, Kristine; Christensen, Jesper; Rappsilber, Juri

    2014-01-01

    linked to the regulation of different biological processes such as differentiation of embryonic stem cells, inflammatory responses in macrophages, and induction of cellular senescence via regulation of the INK4A-ARF locus. Here we show here that JMJD3 interacts with the tumour suppressor protein p53. We...... find that the interaction is dependent on the p53 tetramerization domain. Following DNA damage, JMJD3 is transcriptionally upregulated and by performing genome-wide mapping of JMJD3, we demonstrate that it binds genes involved in basic cellular processes, as well as genes regulating cell cycle......, response to stress and apoptosis. Moreover, we find that JMJD3 binding sites show significant overlap with p53 bound promoters and enhancer elements. The binding of JMJD3 to p53 target sites is increased in response to DNA damage, and we demonstrate that the recruitment of JMJD3 to these sites is dependent...

  12. Role of the SUMO-interacting motif in HIPK2 targeting to the PML nuclear bodies and regulation of p53

    International Nuclear Information System (INIS)

    Sung, Ki Sa; Lee, Yun-Ah; Kim, Eui Tae; Lee, Seung-Rock; Ahn, Jin-Hyun; Choi, Cheol Yong

    2011-01-01

    Homeodomain-interacting protein kinase 2 (HIPK2) is a key regulator of various transcription factors including p53 and CtBP in the DNA damage signaling pathway. PML-nuclear body (NB) is required for HIPK2-mediated p53 phosphorylation at Ser46 and induction of apoptosis. Although PML-NB targeting of HIPK2 has been shown, much is not clear about the molecular mechanism of HIPK2 recruitment to PML-NBs. Here we show that HIPK2 colocalizes specifically with PML-I and PML-IV. Mutational analysis showed that HIPK2 recruitment to PML-IV-NBs is mediated by the SUMO-interaction motifs (SIMs) of both PML-IV and HIPK2. Wild-type HIPK2 associated with SUMO-conjugated PML-IV at a higher affinity than with un-conjugated PML-IV, while the association of a HIPK2 SIM mutant with SUMO-modified PML-IV was impaired. In colony formation assays, HIPK2 strongly suppressed cell proliferation, but HIPK2 SIM mutants did not. In addition, activation and phosphorylation of p53 at the Ser46 residue were impaired by HIPK2 SIM mutants. These results suggest that SIM-mediated HIPK2 targeting to PML-NBs is crucial for HIPK2-mediated p53 activation and induction of apoptosis.

  13. Actinomycin D synergistically enhances the cytotoxicity of CDDP on KB cells by activating P53 via decreasing P53-MDM2 complex.

    Science.gov (United States)

    Wang, Lin; Pang, Xiao-Cong; Yu, Zi-Ru; Yang, Sheng-Qian; Liu, Ai-Lin; Wang, Jin-Hua; Du, Guan-Hua

    2017-06-01

    The aim of this study is to investigate the synergism of low dose of actinomycin D (LDActD) to the cytotoxicity of cisplatin (CDDP) on KB cells. The role of P53 reactivation by LDActD in the synergism and its mechanism were further studied. Cell viability was determined by MTT assay. Apoptosis was determined by AnnexinV-FITC/PI staining. Mitochondrial membrane potential (MMP) was detected by JC-1 staining. Expression of proteins was detected by Western blotting (WB) and/or immunofluorescence (IF). Molecular docking of actinomycin D (ACTD) to Mouse double minute 2 homolog (MDM2) and Mouse double minute 2 homolog X (MDMX). MDMX was analyzed by Discovery Studio. The content of P53-MDM2 complex was detected by ELISA assay. The cytotoxicity of CDDP was increased by the combination of LDActD in kinds of cancer cells. Molecular docking showed strong interaction between ACTD and MDM2/MDMX. Meanwhile, LDActD significantly decreased P53-MDM2 complex. Significant increase of the apoptotic activity by the combination therapy in KB cells is P53 upregulated modulator of apoptosis (PUMA) dependent. In addition to the decrease in MMP, LDActD increased P53 regulated protein and decreased BCL-XL in KB cells. LDActD efficiently enhanced the cytotoxicity of CDDP in cancer cells and induced P53-PUMA-dependent and mitochondria-mediated apoptosis in KB cells. The reactivation of P53 was probably achieved by disturbing the interaction of P53 and MDM2/MDMX.

  14. The PRR11-SKA2 Bidirectional Transcription Unit Is Negatively Regulated by p53 through NF-Y in Lung Cancer Cells

    Directory of Open Access Journals (Sweden)

    Yitao Wang

    2017-03-01

    Full Text Available We previously identified proline-rich protein 11 (PRR11 as a novel cancer-related gene that is implicated in the regulation of cell cycle and tumorigenesis. Our recent study demonstrated that PRR11 and its adjacent gene, kinetochore associated 2 (SKA2, constitute a classic head-to-head gene pair that is coordinately regulated by nuclear factor Y (NF-Y. In the present study, we further show that the PRR11-SKA2 bidirectional transcription unit is an indirect target of the tumor suppressor p53. A luciferase reporter assay revealed that overexpression of wild type p53, but not mutant p53, significantly represses the basal activity and NF-Y mediated transactivation of the PRR11-SKA2 bidirectional promoter. Deletion and mutation analysis of the PRR11-SKA2 promoter revealed that p53-mediated PRR11-SKA2 repression is dependent on the presence of functional NF-Y binding sites. Furthermore, a co-immunoprecipitation assay revealed that p53 associates with NF-Y in lung cancer cells, and a chromatin immunoprecipitation assay showed that p53 represses PRR11-SKA2 transcription by reducing the binding amount of NF-Y in the PRR11-SKA2 promoter region. Consistently, the ability of p53 to downregulate PRR11-SKA2 transcription was significantly attenuated upon siRNA-mediated depletion of nuclear factor Y subunit beta (NF-YB. Notably, lung cancer patients with lower expression of either PRR11 or SKA2 along with wild type p53 exhibited the best overall survival compared with others with p53 mutation and/or higher expression of either PRR11 or SKA2. Taken together, our results demonstrate that p53 negatively regulates the expression of the PRR11-SKA2 bidirectional transcription unit through NF-Y, suggesting that the inability to repress the PRR11-SKA2 bidirectional transcription unit after loss of p53 might contribute to tumorigenesis.

  15. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  17. 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.

  18. 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.

  19. The role of p53 in lung macrophages following exposure to a panel of manufactured nanomaterials

    DEFF Research Database (Denmark)

    Belade, Esther; Chrusciel, Sandra; Armand, Lucie

    2015-01-01

    is a key transcription factor implicated in cellular defence and reparative responses to various stress factors. Additionally, p53 has been implicated in cellular responses following exposure to some MNMs. Here, the role of the MNM mediated p53 induction and activation and its downstream effects following...... exposure to five well-characterised materials [namely two types of TiO2, two carbon black (CB), and one single-walled carbon nanotube (SWCNT)] were investigated. MNM internalisation, cellular viability, p53 protein induction and activation, oxidative stress, inflammation and apoptosis were measured...... in murine cell line and primary pulmonary macrophage models. It was observed that p53 was implicated in the biological responses to MNMs, with oxidative stress associated with p53 activation (only following exposure to the SWCNT). We demonstrate that p53 acted as an antioxidant and anti...

  20. The pro-survival function of p53 in HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Kyu; Kang, Mi Young; Jang, Eun Yeong; Kim, Jin Hong [Korea Atomic Energy Research Institute, Advanced Radiation Technology Institute, Jeongeup (Korea, Republic of)

    2014-11-15

    The rate of apoptosis and autophagy was variable with different p53 status after IR treatment of cells. The influence of p53 status on cell fate suggests a role of p53 in two fundamentally important cell biological pathways: autophagy and apoptosis. p53 coordinates cell cycle arrest and apoptosis to govern cell fate. This study was done to identify p53-mediated regulation of cell's fate. Autophagy induced by IR may prevent cells from undergoing apoptosis, implying an interlink modulation between autophagy and apoptosis. The rate of apoptosis and autophagy was determined with different p53 status after IR treatment of HeLa cells in this study. Our research on IR-induced cellular responses may provide new information about fate decision between the processes of apoptosis and autophagy.

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

    Directory of Open Access Journals (Sweden)

    Ruo-Chia Tseng

    2009-08-01

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

  2. Integral analysis of p53 and its value as prognostic factor in sporadic colon cancer

    International Nuclear Information System (INIS)

    Fariña Sarasqueta, Arantza; Morreau, Hans; Forte, Giusi; Corver, Wim E; Miranda, Noel F de; Ruano, Dina; Eijk, Ronald van; Oosting, Jan; Tollenaar, Rob AEM; Wezel, Tom van

    2013-01-01

    p53 (encoded by TP53) is involved in DNA damage repair, cell cycle regulation, apoptosis, aging and cellular senescence. TP53 is mutated in around 50% of human cancers. Nevertheless, the consequences of p53 inactivation in colon cancer outcome remain unclear. Recently, a new role of p53 together with CSNK1A1 in colon cancer invasiveness has been described in mice. By combining data on different levels of p53 inactivation, we aimed to predict p53 functionality and to determine its effects on colon cancer outcome. Moreover, survival effects of CSNK1A1 together with p53 were also studied. Eighty-three formalin fixed paraffin embedded colon tumors were enriched for tumor cells using flow sorting, the extracted DNA was used in a custom SNP array to determine chr17p13-11 allelic state; p53 immunostaining, TP53 exons 5, 6, 7 and 8 mutations were determined in combination with mRNA expression analysis on frozen tissue. Patients with a predicted functional p53 had a better prognosis than patients with non functional p53 (Log Rank p=0.009). Expression of CSNK1A1 modified p53 survival effects. Patients with low CSNK1A1 expression and non-functional p53 had a very poor survival both in the univariate (Log Rank p<0.001) and in the multivariate survival analysis (HR=4.74 95% CI 1.45 – 15.3 p=0.009). The combination of mutational, genomic, protein and downstream transcriptional activity data predicted p53 functionality which is shown to have a prognostic effect on colon cancer patients. This effect was specifically modified by CSKN1A1 expression

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

    Science.gov (United States)

    Cox, Darren P

    2012-01-01

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

  4. Stabilization and activation of p53 are regulated independently by different phosphorylation events

    OpenAIRE

    Chernov, Mikhail V.; Ramana, Chilakamarti V.; Adler, Victor V.; Stark, George R.

    1998-01-01

    Treatment of mouse or human cells with the protein kinase C (PKC) inhibitors H7 or bisindolylmaleimide I induced an increase in the lifetime of p53, leading to its accumulation. In inhibitor-treated cells, p53 translocated to the nuclei and bound to DNA but was not competent to induce transcription. However, transactivation could be induced by subsequent DNA damage. Phorbol ester, a potent activator of PKC, significantly inhibited the accumulation of p53 after DNA damage. Therefore, constitut...

  5. Hypoxia-induced p53 modulates both apoptosis and radiosensitivity via AKT

    Science.gov (United States)

    Leszczynska, Katarzyna B.; Foskolou, Iosifina P.; Abraham, Aswin G.; Anbalagan, Selvakumar; Tellier, Céline; Haider, Syed; Span, Paul N.; O’Neill, Eric E.; Buffa, Francesca M.; Hammond, Ester M.

    2015-01-01

    Restoration of hypoxia-induced apoptosis in tumors harboring p53 mutations has been proposed as a potential therapeutic strategy; however, the transcriptional targets that mediate hypoxia-induced p53-dependent apoptosis remain elusive. Here, we demonstrated that hypoxia-induced p53-dependent apoptosis is reliant on the DNA-binding and transactivation domains of p53 but not on the acetylation sites K120 and K164, which, in contrast, are essential for DNA damage–induced, p53-dependent apoptosis. Evaluation of hypoxia-induced transcripts in multiple cell lines identified a group of genes that are hypoxia-inducible proapoptotic targets of p53, including inositol polyphosphate-5-phosphatase (INPP5D), pleckstrin domain–containing A3 (PHLDA3), sulfatase 2 (SULF2), B cell translocation gene 2 (BTG2), cytoplasmic FMR1-interacting protein 2 (CYFIP2), and KN motif and ankyrin repeat domains 3 (KANK3). These targets were also regulated by p53 in human cancers, including breast, brain, colorectal, kidney, bladder, and melanoma cancers. Downregulation of these hypoxia-inducible targets associated with poor prognosis, suggesting that hypoxia-induced apoptosis contributes to p53-mediated tumor suppression and treatment response. Induction of p53 targets, PHLDA3, and a specific INPP5D transcript mediated apoptosis in response to hypoxia through AKT inhibition. Moreover, pharmacological inhibition of AKT led to apoptosis in the hypoxic regions of p53-deficient tumors and consequently increased radiosensitivity. Together, these results identify mediators of hypoxia-induced p53-dependent apoptosis and suggest AKT inhibition may improve radiotherapy response in p53-deficient tumors. PMID:25961455

  6. Changes in protein expression in p53 deleted spontaneous thymic lymphomas

    DEFF Research Database (Denmark)

    Honoré, Bent; Vorum, Henrik; Pedersen, Anders Elm

    2004-01-01

    with the protein expression in p53+/+ and p53-/- thymocytes. Only a minority (13 proteins) of the quantitatively changed proteins were common for the two thymic lymphoma cell lines, suggesting that the p53 deficiency mainly results in genetic dysfunctions which are individual for a given tumor. Two of the detected...... structure containing motifs of the glyoxalase-bleomycin resistance protein family (MDR) as deduced from the cDNA....

  7. The prognostic value of p53 positive in colorectal cancer: A retrospective cohort study.

    Science.gov (United States)

    Wang, Peng; Liang, Jianwei; Wang, Zheng; Hou, Huirong; Shi, Lei; Zhou, Zhixiang

    2017-05-01

    This retrospective cohort study aimed to discuss the prognostic value of p53 positive in colorectal cancer. A total of 124 consecutive patients diagnosed with colorectal cancer were evaluated at the National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College from 1 January 2009 to 31 December 2010. The expression of p53 in colorectal cancer was examined by immunohistochemistry. Based on the expression levels of p53, the 124 patients were divided into a p53 positive group and a p53 negative group. In this study, 72 patients were in the p53 positive group and 52 in the p53 negative group. The two groups were well balanced in gender, age, body mass index, American Society of Anesthesiologists scores, and number of lymph nodes harvested. p53 positive was associated with carcinoembryonic antigen ≥5 ng/mL ( p = 0.036), gross type ( p = 0.037), degree of tumor differentiation ( p = 0.026), pathological tumor stage ( p = 0.019), pathological node stage ( p = 0.004), pathological tumor-node-metastasis stage ( p = 0.017), nerve invasion ( p = 0.008), and vessel invasion ( p = 0.018). Tumor site, tumor size, and pathological pattern were not significantly different between these two groups. Disease-free survival and overall survival in the p53 positive group were significantly shorter than the p53 negative group ( p = 0.021 and 0.025, respectively). Colorectal cancer patients with p53 positive tended to be related to a higher degree of malignancy, advanced tumor-node-metastasis stage, and shorter disease-free survival and overall survival. p53 positive was independently an unfavorable prognostic marker for colorectal cancer patients.

  8. P53- and mevalonate pathway–driven malignancies require Arf6 for metastasis and drug resistance

    Science.gov (United States)

    Hashimoto, Ari; Oikawa, Tsukasa; Hashimoto, Shigeru; Sugino, Hirokazu; Yoshikawa, Ayumu; Otsuka, Yutaro; Handa, Haruka; Onodera, Yasuhito; Nam, Jin-Min; Oneyama, Chitose; Okada, Masato; Fukuda, Mitsunori

    2016-01-01

    Drug resistance, metastasis, and a mesenchymal transcriptional program are central features of aggressive breast tumors. The GTPase Arf6, often overexpressed in tumors, is critical to promote epithelial–mesenchymal transition and invasiveness. The metabolic mevalonate pathway (MVP) is associated with tumor invasiveness and known to prenylate proteins, but which prenylated proteins are critical for MVP-driven cancers is unknown. We show here that MVP requires the Arf6-dependent mesenchymal program. The MVP enzyme geranylgeranyl transferase II (GGT-II) and its substrate Rab11b are critical for Arf6 trafficking to the plasma membrane, where it is activated by receptor tyrosine kinases. Consistently, mutant p53, which is known to support tumorigenesis via MVP, promotes Arf6 activation via GGT-II and Rab11b. Inhibition of MVP and GGT-II blocked invasion and metastasis and reduced cancer cell resistance against chemotherapy agents, but only in cells overexpressing Arf6 and components of the mesenchymal program. Overexpression of Arf6 and mesenchymal proteins as well as enhanced MVP activity correlated with poor patient survival. These results provide insights into the molecular basis of MVP-driven malignancy. PMID:27044891

  9. 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...

  10. 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

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Paola De Feudis

    2000-05-01

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

  13. Pigmentation, Melanocyte Colonization, and p53 Status in Basal Cell Carcinoma

    International Nuclear Information System (INIS)

    Frey, L. M.; Houben, R.; Brocker, E. B.

    2011-01-01

    Basal cell carcinoma (BCC) is the most common neoplasm in the Caucasian population. Only a fraction of BCC exhibits pigmentation. Lack of melanocyte colonization has been suggested to be due to p53-inactivating mutations in the BCC cells interfering with the p53-proopiomelanocortin pathway and the production of alpha melanocyte-stimulating hormone in the tumor. To evaluate this, we determined tumor pigmentation as well as expression of melan-A and of p53 in 49 BCC tissues by means of immunohistochemistry. As expected, we observed a positive relation between tumor pigmentation and melan-A positive intra-tumoral melanocytes. Melanocyte colonization and, to a lesser extent, p53 overexpression showed intraindividual heterogeneity in larger tumors. p53 overexpression, which is indicative of p53 mutations, was not correlated to melanocyte colonization of BCC. Sequencing of exon 5-8 of the p53 gene in selected BCC cases revealed that colonization by melanocytes and BCC pigmentation is neither ablated by p53 mutations nor generally present in BCCs with wild-type p53.

  14. A Novel Protein Interaction between Nucleotide Binding Domain of Hsp70 and p53 Motif

    Directory of Open Access Journals (Sweden)

    Asita Elengoe

    2015-01-01

    Full Text Available Currently, protein interaction of Homo sapiens nucleotide binding domain (NBD of heat shock 70 kDa protein (PDB: 1HJO with p53 motif remains to be elucidated. The NBD-p53 motif complex enhances the p53 stabilization, thereby increasing the tumor suppression activity in cancer treatment. Therefore, we identified the interaction between NBD and p53 using STRING version 9.1 program. Then, we modeled the three-dimensional structure of p53 motif through homology modeling and determined the binding affinity and stability of NBD-p53 motif complex structure via molecular docking and dynamics (MD simulation. Human DNA binding domain of p53 motif (SCMGGMNR retrieved from UniProt (UniProtKB: P04637 was docked with the NBD protein, using the Autodock version 4.2 program. The binding energy and intermolecular energy for the NBD-p53 motif complex were −0.44 Kcal/mol and −9.90 Kcal/mol, respectively. Moreover, RMSD, RMSF, hydrogen bonds, salt bridge, and secondary structure analyses revealed that the NBD protein had a strong bond with p53 motif and the protein-ligand complex was stable. Thus, the current data would be highly encouraging for designing Hsp70 structure based drug in cancer therapy.

  15. Increased p53 immunopositivity in anaplastic medulloblastoma and supratentorial PNET is not caused by JC virus

    International Nuclear Information System (INIS)

    Eberhart, Charles G; Chaudhry, Aneeka; Daniel, Richard W; Khaki, Leila; Shah, Keerti V; Gravitt, Patti E

    2005-01-01

    p53 mutations are relatively uncommon in medulloblastoma, but abnormalities in this cell cycle pathway have been associated with anaplasia and worse clinical outcomes. We correlated p53 protein expression with pathological subtype and clinical outcome in 75 embryonal brain tumors. The presence of JC virus, which results in p53 protein accumulation, was also examined. p53 protein levels were evaluated semi-quantitatively in 64 medulloblastomas, 3 atypical teratoid rhabdoid tumors (ATRT), and 8 supratentorial primitive neuroectodermal tumors (sPNET) using immunohistochemistry. JC viral sequences were analyzed in DNA extracted from 33 frozen medulloblastoma and PNET samples using quantitative polymerase chain reaction. p53 expression was detected in 18% of non-anaplastic medulloblastomas, 45% of anaplastic medulloblastomas, 67% of ATRT, and 88% of sPNET. The increased p53 immunoreactivity in anaplastic medulloblastoma, ATRT, and sPNET was statistically significant. Log rank analysis of clinical outcome revealed significantly shorter survival in patients with p53 immunopositive embryonal tumors. No JC virus was identified in the embryonal brain tumor samples, while an endogenous human retrovirus (ERV-3) was readily detected. Immunoreactivity for p53 protein is more common in anaplastic medulloblastomas, ATRT and sPNET than in non-anaplastic tumors, and is associated with worse clinical outcomes. However, JC virus infection is not responsible for increased levels of p53 protein

  16. Increased p53 immunopositivity in anaplastic medulloblastoma and supratentorial PNET is not caused by JC virus

    Directory of Open Access Journals (Sweden)

    Shah Keerti V

    2005-02-01

    Full Text Available Abstract Background p53 mutations are relatively uncommon in medulloblastoma, but abnormalities in this cell cycle pathway have been associated with anaplasia and worse clinical outcomes. We correlated p53 protein expression with pathological subtype and clinical outcome in 75 embryonal brain tumors. The presence of JC virus, which results in p53 protein accumulation, was also examined. Methods p53 protein levels were evaluated semi-quantitatively in 64 medulloblastomas, 3 atypical teratoid rhabdoid tumors (ATRT, and 8 supratentorial primitive neuroectodermal tumors (sPNET using immunohistochemistry. JC viral sequences were analyzed in DNA extracted from 33 frozen medulloblastoma and PNET samples using quantitative polymerase chain reaction. Results p53 expression was detected in 18% of non-anaplastic medulloblastomas, 45% of anaplastic medulloblastomas, 67% of ATRT, and 88% of sPNET. The increased p53 immunoreactivity in anaplastic medulloblastoma, ATRT, and sPNET was statistically significant. Log rank analysis of clinical outcome revealed significantly shorter survival in patients with p53 immunopositive embryonal tumors. No JC virus was identified in the embryonal brain tumor samples, while an endogenous human retrovirus (ERV-3 was readily detected. Conclusion Immunoreactivity for p53 protein is more common in anaplastic medulloblastomas, ATRT and sPNET than in non-anaplastic tumors, and is associated with worse clinical outcomes. However, JC virus infection is not responsible for increased levels of p53 protein.

  17. Increased p53 immunopositivity in anaplastic medulloblastoma and supratentorial PNET is not caused by JC virus

    Science.gov (United States)

    Eberhart, Charles G; Chaudhry, Aneeka; Daniel, Richard W; Khaki, Leila; Shah, Keerti V; Gravitt, Patti E

    2005-01-01

    Background p53 mutations are relatively uncommon in medulloblastoma, but abnormalities in this cell cycle pathway have been associated with anaplasia and worse clinical outcomes. We correlated p53 protein expression with pathological subtype and clinical outcome in 75 embryonal brain tumors. The presence of JC virus, which results in p53 protein accumulation, was also examined. Methods p53 protein levels were evaluated semi-quantitatively in 64 medulloblastomas, 3 atypical teratoid rhabdoid tumors (ATRT), and 8 supratentorial primitive neuroectodermal tumors (sPNET) using immunohistochemistry. JC viral sequences were analyzed in DNA extracted from 33 frozen medulloblastoma and PNET samples using quantitative polymerase chain reaction. Results p53 expression was detected in 18% of non-anaplastic medulloblastomas, 45% of anaplastic medulloblastomas, 67% of ATRT, and 88% of sPNET. The increased p53 immunoreactivity in anaplastic medulloblastoma, ATRT, and sPNET was statistically significant. Log rank analysis of clinical outcome revealed significantly shorter survival in patients with p53 immunopositive embryonal tumors. No JC virus was identified in the embryonal brain tumor samples, while an endogenous human retrovirus (ERV-3) was readily detected. Conclusion Immunoreactivity for p53 protein is more common in anaplastic medulloblastomas, ATRT and sPNET than in non-anaplastic tumors, and is associated with worse clinical outcomes. However, JC virus infection is not responsible for increased levels of p53 protein. PMID:15717928

  18. Correlation between p53 expression and clinical-pathological characteristics of gastric cancer

    Directory of Open Access Journals (Sweden)

    Radovanović Dragče

    2011-01-01

    Full Text Available Backgraund/Aim. Gene p53, or “cell genome keeper”, has a preventive effect on the occurrence of genetic aberrations and prevents abnormal expansion of (tumor cells. In gastric cancer cells in most cases we register high expression of mutated p53 gene, which correlates with prognosis and specific clinicalpathological characteristics of gastric cancer. Methods. Using the imunohistochemical method we determined the level of expression of p53 protein in 62 gastric cancers and 30 precancerous conditions (intestinal metaplasia of the stomach. We analyzed the relationship of the level of p53 expression and clinical pathological characteristics of gastric cancer. Results. Expression of p53 was positive in 42 (67.7% tumor cases and in 7 (14.3% cases of intestinal metaplasia. Expression of P53 and stomach cancer were in direct correlation (p = 0.000. Sensitivity for p53 in stomach cancer cases was 67.7% (42/62, and specifility was 76.7% (23/30. Expression of mutated p53 protein was in direct correlation with the invasion of lymph nodes (p = 0.034 and with invasion of blood vessels by carcinoma cells (p = 0.042. Conclusion. There is a direct correlation between p53 expression and gastric cancer and it indicates the ability of carcinoma cells to invade blood vessels.

  19. p53 Dependent Centrosome Clustering Prevents Multipolar Mitosis in Tetraploid Cells

    Science.gov (United States)

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

    2011-01-01

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

  20. 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

  1. 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

  2. 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

  3. 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.

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

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    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.

  5. p53 Represses the Oncogenic Sno-MiR-28 Derived from a SnoRNA.

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    Feng Yu

    Full Text Available p53 is a master tumour repressor that participates in vast regulatory networks, including feedback loops involving microRNAs (miRNAs that regulate p53 and that themselves are direct p53 transcriptional targets. We show here that a group of polycistronic miRNA-like non-coding RNAs derived from small nucleolar RNAs (sno-miRNAs are transcriptionally repressed by p53 through their host gene, SNHG1. The most abundant of these, sno-miR-28, directly targets the p53-stabilizing gene, TAF9B. Collectively, p53, SNHG1, sno-miR-28 and TAF9B form a regulatory loop which affects p53 stability and downstream p53-regulated pathways. In addition, SNHG1, SNORD28 and sno-miR-28 are all significantly upregulated in breast tumours and the overexpression of sno-miR-28 promotes breast epithelial cell proliferation. This research has broadened our knowledge of the crosstalk between small non-coding RNA pathways and roles of sno-miRNAs in p53 regulation.

  6. Loss of p53 induces M-phase retardation following G2 DNA damage checkpoint abrogation.

    Science.gov (United States)

    Minemoto, Yuzuru; Uchida, Sanae; Ohtsubo, Motoaki; Shimura, Mari; Sasagawa, Toshiyuki; Hirata, Masato; Nakagama, Hitoshi; Ishizaka, Yukihito; Yamashita, Katsumi

    2003-04-01

    Most cell lines that lack functional p53 protein are arrested in the G2 phase of the cell cycle due to DNA damage. When the G2 checkpoint is abrogated, these cells are forced into mitotic catastrophe. A549 lung adenocarcinoma cells, in which p53 was eliminated with the HPV16 E6 gene, exhibited efficient arrest in the G2 phase when treated with adriamycin. Administration of caffeine to G2-arrested cells induced a drastic change in cell phenotype, the nature of which depended on the status of p53. Flow cytometric and microscopic observations revealed that cells that either contained or lacked p53 resumed their cell cycles and entered mitosis upon caffeine treatment. However, transit to the M phase was slower in p53-negative cells than in p53-positive cells. Consistent with these observations, CDK1 activity was maintained at high levels, along with stable cyclin B1, in p53-negative cells. The addition of butyrolactone I, which is an inhibitor of CDK1 and CDK2, to the p53-negative cells reduced the floating round cell population and induced the disappearance of cyclin B1. These results suggest a relationship between the p53 pathway and the ubiquitin-mediated degradation of mitotic cyclins and possible cross-talk between the G2-DNA damage checkpoint and the mitotic checkpoint.

  7. p53 functions as a cell cycle control protein in osteosarcomas.

    OpenAIRE

    Diller, L; Kassel, J; Nelson, C E; Gryka, M A; Litwak, G; Gebhardt, M; Bressac, B; Ozturk, M; Baker, S J; Vogelstein, B

    1990-01-01

    Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfect...

  8. An early function of the adenoviral E1B 55 kDa protein is required for the nuclear relocalization of the cellular p53 protein in adenovirus-infected normal human cells

    International Nuclear Information System (INIS)

    Cardoso, F.M.; Kato, Sayuri E.M.; Huang Wenying; Flint, S. Jane; Gonzalez, Ramon A.

    2008-01-01

    It is well established that the human subgroup C adenovirus type 5 (Ad5) E1B 55 kDa protein can regulate the activity and concentration of the cellular tumor suppressor, p53. However, the contribution(s) of these functions of the E1B protein to viral reproduction remains unclear. To investigate this issue, we examined properties of p53 in normal human cells infected by E1B mutant viruses that display defective entry into the late phase or viral late mRNA export. The steady-state concentrations of p53 were significantly higher in cells infected by the E1B 55 kDa null mutant Hr6 or three mutants carrying small insertions in the E1B 55 kDa protein coding sequence than in Ad5-infected cells. Nevertheless, none of the mutants induced apoptosis in infected cells. Rather, the localization of p53 to E1B containing nuclear sites observed during infection by Ad5 was prevented by mutations that impair interaction of the E1B protein with p53 and/or with the E4 Orf6 protein. These results indicate that the E1B protein fulfills an early function that correlates efficient entry into the late phase with the localization of E1B and p53 in the nucleus of Ad5-infected normal human cells

  9. p53 inactivation decreases dependence on estrogen/ERK signalling for proliferation but promotes EMT and susceptility to 3-bromopyruvate in ERα+ breast cancer MCF-7 cells.

    Science.gov (United States)

    Rieber, Manuel; Strasberg-Rieber, Mary

    2014-03-15

    Most breast cancers express the estrogen receptor alpha (ERα(+)), harbor wt TP53, depend on estrogen/ERK signalling for proliferation, and respond to anti-estrogens. However, concomittant activation of the epidermal growth factor receptor (EGFR)/MEK pathway promotes resistance by decreasing estrogen dependence. Previously, we showed that retroviral transduction of mutant p53 R175H into wt TP53 ERα(+) MCF-7 cells induces epidermal growth factor (EGF)-independent proliferation, activation of the EGF receptor (p-EGFR) and some characteristics of epithelial-mesenchymal transition (EMT). To investigate whether p53 inactivation augments ERα(+) cell proliferation in response to restrictive estradiol, chemical MEK inhibition or metabolic inhibitors. Introduction of mutant p53 R175H lowered expression of p53-dependent PUMA and p21WAF1, decreased E-cadherin and cytokeratin 18 associated with EMT, but increased the % of proliferating ERα(+)/Ki67 cells, diminishing estrogen dependence. These cells also exhibited higher proliferation in the presence of MEK-inhibitor UO126, reciprocally correlating with preferential susceptibility to the pyruvate analog 3-bromopyruvate (3-BrPA) without a comparable response to 2-deoxyglucose. p53 siRNA silencing by electroporation in wt TP53 MCF-7 cells also decreased estrogen dependence and response to MEK inhibition, while also conferring susceptibility to 3-BrPA. (a) ERα(+) breast cancer cells dysfunctional for TP53 which proliferate irrespective of low estrogen and chemical MEK inhibition are likely to increase metabolic consumption becoming increasingly susceptible to 3-BrPA; (b) targeting the pyruvate pathway may improve response to endocrine therapy in ERα(+) breast cancer with p53 dysfunction. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Arsenic promotes centrosome abnormalities and cell colony formation in p53 compromised human lung cells

    International Nuclear Information System (INIS)

    Liao Weiting; Lin Pinpin; Cheng, T.-S.; Yu, H.-S.; Chang, Louis W.

    2007-01-01

    Epidemiological evidence indicated that residents, especially cigarette smokers, in arseniasis areas had significantly higher lung cancer risk than those living in non-arseniasis areas. Thus, an interaction between arsenic and cigarette smoking in lung carcinogenesis was suspected. p53 dysfunction or mutation in lung epithelial cells was frequently observed in cigarette smokers. Our present study was to explore the differential effects by arsenic on H1355 cells (human lung adenocarcinoma cell line with mutation in p53), BEAS-2B (immortalized lung epithelial cell with functional p53) and pifithrin-α-treated BEAS-2B cells (p53-inhibited cells). These cells were treated with different doses of sodium arsenite (0, 0.1, 1, 5 and 10 μM) for 48 h. A greater reduction in cell viability was observed in the BEAS-2B cells vs. p53 compromised cells (H1355 or p53-inhibited BEAS-2B). Similar observation was also made on 7-day cell survival (growth) study. TUNEL analysis confirmed that there was indeed a significantly reduced arsenite-induced apoptosis found in p53-compromised cells. Centrosomal abnormality has been attributed to eventual chromosomal missegregation, aneuploidy and tumorigenesis. In our present study, reduced p21 and Gadd45a expressions and increased centrosomal abnormality (atopic and multiple centrosomes) were observed in both arsenite-treated H1355 and p53-inhibited BEAS-2B cells as compared with similarly treated BEAS-2B cells. Increased anchorage-independent growth (colony formation) of BEAS-2B cells co-treated with pifithrin-α and 5 μM sodium arsenite was also observed in soft agar. Our present investigation demonstrated that arsenic would act specifically on p53 compromised cells (either with p53 dysfunction or inhibited) to induce centrosomal abnormality and colony formation. These findings provided strong evidence on the carcinogenic promotional role of arsenic, especially under the condition of p53 dysfunction

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

    International Nuclear Information System (INIS)

    Szybka, Malgorzata; Kordek, Radzislaw; Zakrzewska, Magdalena; Rieske, Piotr; Pasz-Walczak, Grazyna; Kulczycka-Wojdala, Dominika; Zawlik, Izabela; Stawski, Robert; Jesionek-Kupnicka, Dorota; Liberski, Pawel P

    2009-01-01

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

  12. Chemotherapy-Induced Apoptosis in a Transgenic Model of Neuroblastoma Proceeds Through p53 Induction

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    Louis Chesler

    2008-11-01

    Full Text Available Chemoresistance in neuroblastoma is a significant issue complicating treatment of this common pediatric solid tumor. MYCN-amplified neuroblastomas are infrequently mutated at p53 and are chemosensitive at diagnosis but acquire p53 mutations and chemoresistance with relapse. Paradoxically, Myc-driven transformation is thought to require apoptotic blockade. We used the TH-MYCN transgenic murine model to examine the role of p53-driven apoptosis on neuroblastoma tumorigenesis and the response to chemotherapy. Tumors formed with high penetrance and low latency in p53-haploinsufficient TH-MYCN mice. Cyclophosphamide (CPM induced a complete remission in p53 wild type TH-MYCN tumors, mirroring the sensitivity of childhood neuroblastoma to this agent. Treated tumors showed a prominent proliferation block, induction of p53 protein, and massive apoptosis proceeding through induction of the Bcl-2 homology domain-3-only proteins PUMA and Bim, leading to the activation of Bax and cleavage of caspase-3 and -9. Apoptosis induced by CPM was reduced in p53-haploinsufficient tumors. Treatment of MYCN-expressing human neuroblastoma cell lines with CPM induced apoptosis that was suppressible by siRNA to p53. Taken together, the results indicate that the p53 pathway plays a significant role in opposing MYCN-driven oncogenesis in a mouse model of neuroblastoma and that basal inactivation of the pathway is achieved in progressing tumors. This, in part, explains the striking sensitivity of such tumors to chemotoxic agents that induce p53-dependent apoptosis and is consistent with clinical observations that therapy-associated mutations in p53 are a likely contributor to the biology of tumors at relapse and secondarily mediate resistance to therapy.

  13. 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.

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

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    Clarke Alan R

    2002-11-01

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

  15. Minnelide/Triptolide Impairs Mitochondrial Function by Regulating SIRT3 in P53-Dependent Manner in Non-Small Cell Lung Cancer.

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    Ajay Kumar

    Full Text Available Minnelide/Triptolide (TL has recently emerged as a potent anticancer drug in non-small cell lung cancer (NSCLC. However, the precise mechanism of its action remains ambiguous. In this study, we elucidated the molecular basis for TL-induced cell death in context to p53 status. Cell death was attributed to dysfunction of mitochondrial bioenergetics in p53-deficient cells, which was characterized by decreased mitochondrial respiration, steady-state ATP level and membrane potential, but augmented reactive oxygen species (ROS. Increased ROS production resulted in oxidative stress in TL-treated cells. This was exhibited by elevated nuclear levels of a redox-sensitive transcriptional factor, NF-E2-related factor-2 (NRF2, along with diminished cellular glutathione (GSH content. We further demonstrated that in the absence of p53, TL blunted the expression of mitochondrial SIRT3 triggering increased acetylation of NDUAF9 and succinate dehydrogenase, components of complexes I and II of the electron transport chain (ETC. TL-mediated hyperacetylation of complexes I and II proteins and these complexes displayed decreased enzymatic activities. We also provide the evidence that P53 regulate steady-state level of SIRT3 through Proteasome-Pathway. Finally, forced overexpression of Sirt3, but not deacetylase-deficient mutant of Sirt3 (H243Y, restored the deleterious effect of TL on p53-deficient cells by rescuing mitochondrial bioenergetics. On contrary, Sirt3 deficiency in the background of wild-type p53 triggered TL-induced mitochondrial impairment that echoed TL effect in p53-deficeint cells. These findings illustrate a novel mechanism by which TL exerts its potent effects on mitochondrial function and ultimately the viability of NSCLC tumor.

  16. p53 Mutagenesis by Benzo[a]pyrene derived Radical Cations

    Science.gov (United States)

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

    2013-01-01

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

  17. 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

  18. Detection of ATM germline variants by the p53 mitotic centrosomal localization test in BRCA1/2-negative patients with early-onset breast cancer.

    Science.gov (United States)

    Prodosmo, Andrea; Buffone, Amelia; Mattioni, Manlio; Barnabei, Agnese; Persichetti, Agnese; De Leo, Aurora; Appetecchia, Marialuisa; Nicolussi, Arianna; Coppa, Anna; Sciacchitano, Salvatore; Giordano, Carolina; Pinnarò, Paola; Sanguineti, Giuseppe; Strigari, Lidia; Alessandrini, Gabriele; Facciolo, Francesco; Cosimelli, Maurizio; Grazi, Gian Luca; Corrado, Giacomo; Vizza, Enrico; Giannini, Giuseppe; Soddu, Silvia

    2016-09-06

    Variant ATM heterozygotes have an increased risk of developing cancer, cardiovascular diseases, and diabetes. Costs and time of sequencing and ATM variant complexity make large-scale, general population screenings not cost-effective yet. Recently, we developed a straightforward, rapid, and inexpensive test based on p53 mitotic centrosomal localization (p53-MCL) in peripheral blood mononuclear cells (PBMCs) that diagnoses mutant ATM zygosity and recognizes tumor-associated ATM polymorphisms. Fresh PBMCs from 496 cancer patients were analyzed by p53-MCL: 90 cases with familial BRCA1/2-positive and -negative breast and/or ovarian cancer, 337 with sporadic cancers (ovarian, lung, colon, and post-menopausal breast cancers), and 69 with breast/thyroid cancer. Variants were confirmed by ATM sequencing. A total of seven individuals with ATM variants were identified, 5/65 (7.7 %) in breast cancer cases of familial breast and/or ovarian cancer and 2/69 (2.9 %) in breast/thyroid cancer. No variant ATM carriers were found among the other cancer cases. Excluding a single case in which both BRCA1 and ATM were mutated, no p53-MCL alterations were observed in BRCA1/2-positive cases. These data validate p53-MCL as reliable and specific test for germline ATM variants, confirm ATM as breast cancer susceptibility gene, and highlight a possible association with breast/thyroid cancers.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-09-07

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

  20. Isolation and identification of the human homolog of a new p53-binding protein, Mdmx

    NARCIS (Netherlands)

    Shvarts, A.; Bazuine, M.; Dekker, P.; Ramos, Y. F.; Steegenga, W. T.; Merckx, G.; van Ham, R. C.; van der Houven van Oordt, W.; van der Eb, A. J.; Jochemsen, A. G.

    1997-01-01

    We recently reported the identification of a mouse cDNA encoding a new p53-associating protein that we called Mdmx because of its structural similarity to Mdm2, a well-known p53-binding protein. Here we report the isolation of a cDNA encoding the human homolog of Mdmx. The ORF of the cDNA encodes a

  1. Stress-specific response of the p53-Mdm2 feedback loop

    Directory of Open Access Journals (Sweden)

    Jensen Mogens H

    2010-07-01

    Full Text Available Abstract Background The p53 signalling pathway has hundreds of inputs and outputs. It can trigger cellular senescence, cell-cycle arrest and apoptosis in response to diverse stress conditions, including DNA damage, hypoxia and nutrient deprivation. Signals from all these inputs are channeled through a single node, the transcription factor p53. Yet, the pathway is flexible enough to produce different downstream gene expression patterns in response to different stresses. Results We construct a mathematical model of the negative feedback loop involving p53 and its inhibitor, Mdm2, at the core of this pathway, and use it to examine the effect of different stresses that trigger p53. In response to DNA damage, hypoxia, etc., the model exhibits a wide variety of specific output behaviour - steady states with low or high levels of p53 and Mdm2, as well as spiky oscillations with low or high average p53 levels. Conclusions We show that even a simple negative feedback loop is capable of exhibiting the kind of flexible stress-specific response observed in the p53 system. Further, our model provides a framework for predicting the differences in p53 response to different stresses and single nucleotide polymorphisms.

  2. Polycomb Group Protein PHF1 Regulates p53-dependent Cell Growth Arrest and Apoptosis*

    Science.gov (United States)

    Yang, Yang; Wang, Chenji; Zhang, Pingzhao; Gao, Kun; Wang, Dejie; Yu, Hongxiu; Zhang, Ting; Jiang, Sirui; Hexige, Saiyin; Hong, Zehui; Yasui, Akira; Liu, Jun O.; Huang, Haojie; Yu, Long

    2013-01-01

    Polycomb group protein PHF1 is well known as a component of a novel EED-EZH2·Polycomb repressive complex 2 complex and plays important roles in H3K27 methylation and Hox gene silencing. PHF1 is also involved in the response to DNA double-strand breaks in human cells, promotes nonhomologous end-joining processes through interaction with Ku70/Ku80. Here, we identified another function of PHF1 as a potential p53 pathway activator in a pathway screen using luminescence reporter assay. Subsequent studies showed PHF1 directly interacts with p53 proteins both in vivo and in vitro and co-localized in nucleus. PHF1 binds to the C-terminal regulatory domain of p53. Overexpression of PHF1 elevated p53 protein level and prolonged its turnover. Knockdown of PHF1 reduced p53 protein level and its target gene expression both in normal state and DNA damage response. Mechanically, PHF1 protects p53 proteins from MDM2-mediated ubiquitination and degradation. Furthermore, we showed that PHF1 regulates cell growth arrest and etoposide-induced apoptosis in a p53-dependent manner. Finally, PHF1 expression was significantly down-regulated in human breast cancer samples. Taken together, we establish PHF1 as a novel positive regulator of the p53 pathway. These data shed light on the potential roles of PHF1 in tumorigenesis and/or tumor progression. PMID:23150668

  3. 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.

  4. Synergistic induction of profibrotic PAI-1 by TGF-β and radiation depends on p53

    International Nuclear Information System (INIS)

    Niemantsverdriet, Maarten; Jong, Edwin de; Langendijk, Johannes A.; Kampinga, Harm H.; Coppes, Robert P.

    2010-01-01

    Radiation-induced fibrosis is a severe side effect of radiotherapy. TGF-β and radiation synergistically induce expression of the profibrotic PAI-1 gene and this cooperation potentially involves p53. Here, we demonstrate that p53 is both indispensable and sufficient for the radiation effect inducing synergistic activation of PAI-1 by radiation and TGF-β.

  5. Differential programming of p53-deficient embryonic cells during rotenone block

    Science.gov (United States)

    Mitochondrial dysfunction has been implicated in chemical toxicities. The present study used an in vitro model to investigate the differential expression of metabolic pathways during cellular stress in p53- efficient embryonic fibroblasts compared to p53-deficient cells. These c...

  6. p53, a New Master Regulator of Stem Cell Differentiation | Center for Cancer Research

    Science.gov (United States)

    When the genome is damaged, a key player in stabilizing and maintaining genomic integrity is a protein called p53.  This protein can activate or shut down gene activity in response to DNA damage.  But how exactly does p53 accomplish its task? This question has yet to be answered completely at the molecular level.   

  7. 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.)

  8. p53 Activation following Rift Valley fever virus infection contributes to cell death and viral production.

    Directory of Open Access Journals (Sweden)

    Dana Austin

    Full Text Available Rift Valley fever virus (RVFV is an emerging viral zoonosis that is responsible for devastating outbreaks among livestock and is capable of causing potentially fatal disease in humans. Studies have shown that upon infection, certain viruses have the capability of utilizing particular cellular signaling pathways to propagate viral infection. Activation of p53 is important for the DNA damage signaling cascade, initiation of apoptosis, cell cycle arrest and transcriptional regulation of multiple genes. The current study focuses on the role of p53 signaling in RVFV infection and viral replication. These results show an up-regulation of p53 phosphorylation at several serine sites after RVFV MP-12 infection that is highly dependent on the viral protein NSs. qRT-PCR data showed a transcriptional up-regulation of several p53 targeted genes involved in cell cycle and apoptosis regulation following RVFV infection. Cell viability assays demonstrate that loss of p53 results in less RVFV induced cell death. Furthermore, decreased viral titers in p53 null cells indicate that RVFV utilizes p53 to enhance viral production. Collectively, these experiments indicate that the p53 signaling pathway is utilized during RVFV infection to induce cell death and increase viral production.

  9. The role of p53 and pRB in apoptosis and cancer

    DEFF Research Database (Denmark)

    Hickman, Emma S; Moroni, M Cristina; Helin, Kristian

    2002-01-01

    Loss of function of both the p53 pathway and the retinoblastoma protein (pRB) pathway plays a significant role in the development of most human cancers. Loss of pRB results in deregulated cell proliferation and apoptosis, whereas loss of p53 desensitizes cells to checkpoint signals, including...

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

    Directory of Open Access Journals (Sweden)

    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.

  11. 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

  12. Mutations in the p53 homolog p63: allele-specific developmental syndromes in humans.

    NARCIS (Netherlands)

    Bokhoven, J.H.L.M. van; McKeon, F.

    2002-01-01

    p63 is the most recently discovered but most ancient member of the p53 family. In marked contrast to p53, p63 is highly expressed in embryonic ectoderm and in the basal, regenerative layers of many epithelial tissues in the adult. The p63-knockout mouse dies at birth and lacks limbs, epidermis,

  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. Analysis of P53 mutations and their expression in 56 colorectal cancer cell lines

    DEFF Research Database (Denmark)

    Liu, Ying; Bodmer, Walter F

    2006-01-01

    A comprehensive analysis of the TP53 gene and its protein status was carried out on a panel of 56 colorectal cancer cell lines. This analysis was based on a combination of denaturing HPLC mutation screening of all exons of the p53 gene, sequencing the cDNA, and assessing the function of the p53 p...

  15. 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.

  16. 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.

  17. 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...

  18. 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

  19. 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

  20. Analysis of a p53 Mutation Associated with Cancer Susceptibility for Biochemistry and Genetic Laboratory Courses

    Science.gov (United States)

    Soto-Cruz, Isabel; Legorreta-Herrera, Martha

    2009-01-01

    We have devised and implemented a module for an upper division undergraduate laboratory based on the amplification and analysis of a p53 polymorphism associated with cancer susceptibility. First, students collected a drop of peripheral blood cells using a sterile sting and then used FTA cards to extract the genomic DNA. The p53 region is then PCR…

  1. p53 is important for the anti-proliferative effect of ibuprofen in colon carcinoma cells

    International Nuclear Information System (INIS)

    Janssen, Astrid; Schiffmann, Susanne; Birod, Kerstin; Maier, Thorsten J.; Wobst, Ivonne; Geisslinger, Gerd; Groesch, Sabine

    2008-01-01

    S-ibuprofen which inhibits the cyclooxygenase-1/-2 and R-ibuprofen which shows no COX-inhibition at therapeutic concentrations have anti-carcinogenic effects in human colon cancer cells; however, the molecular mechanisms for these effects are still unknown. Using HCT-116 colon carcinoma cell lines, expressing either the wild-type form of p53 (HCT-116 p53 wt ) or being p(HCT-116 p53 -/- ), we demonstrated that both induction of a cell cycle block and apoptosis after S- and R-ibuprofen treatment is in part dependent on p53. Also in the in vivo nude mice model HCT-116 p53 -/- xenografts were less sensitive for S- and R-ibuprofen treatment than HCT-116 p53 wt cells. Furthermore, results indicate that induction of apoptosis in HCT-116 p53 wt cells after ibuprofen treatment is in part dependent on a signalling pathway including the neutrophin receptor p75 NTR , p53 and Bax

  2. Detection of genotoxic and non-genotoxic carcinogens in Xpc−/−p53+/− mice

    International Nuclear Information System (INIS)

    Melis, Joost P.M.; Speksnijder, Ewoud N.; Kuiper, Raoul V.; Salvatori, Daniela C.F.; Schaap, Mirjam M.; Maas, Saskia; Robinson, Joke; Verhoef, Aart; Benthem, Jan van; Luijten, Mirjam; Steeg, Harry van

    2013-01-01

    An accurate assessment of the carcinogenic potential of chemicals and pharmaceutical drugs is essential to protect humans and the environment. Therefore, substances are extensively tested before they are marketed to the public. Currently, the rodent two-year bioassay is still routinely used to assess the carcinogenic potential of substances. However, over time it has become clear that this assay yields false positive results and also has several economic and ethical drawbacks including the use of large numbers of animals, the long duration, and the high cost. The need for a suitable alternative assay is therefore high. Previously, we have proposed the Xpa*p53 mouse model as a very suitable alternative to the two-year bioassay. We now show that the Xpc*p53 mouse model preserves all the beneficial traits of the Xpa*p53 model for sub-chronic carcinogen identification and can identify both genotoxic and non-genotoxic carcinogens. Moreover, Xpc*p53 mice appear to be more responsive than Xpa*p53 mice towards several genotoxic and non-genotoxic carcinogens. Furthermore, Xpc*p53 mice are far less sensitive than Xpa*p53 mice for the toxic activity of DNA damaging agents and as such clearly respond in a similar way as wild type mice do. These advantageous traits of the Xpc*p53 model make it a better alternative for in vivo carcinogen testing than Xpa*p53. This pilot study suggests that Xpc*p53 mice are suited for routine sub-chronic testing of both genotoxic and non-genotoxic carcinogens and as such represent a suitable alternative to possibly replace the murine life time cancer bioassay. Highlights: ► The Xpc*p53 mouse model is able to identify genotoxic and non-genotoxic carcinogens. ► Time, animals and cost can be significantly reduced compared to the 2-year bioassay. ► Xpc*p53 mice are more advantageous for carcinogen identification than Xpa*p53 mice. ► Xpc*p53 mice exhibit a wild type response upon exposure to genotoxicants.

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

    Directory of Open Access Journals (Sweden)

    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

  4. Cell surface area and membrane folding in glioblastoma cell lines differing in PTEN and p53 status.

    Directory of Open Access Journals (Sweden)

    Simon Memmel

    Full Text Available Glioblastoma multiforme (GBM is characterized by rapid growth, invasion and resistance to chemo-/radiotherapy. The complex cell surface morphology with abundant membrane folds, microvilli, filopodia and other membrane extensions is believed to contribute to the highly invasive behavior and therapy resistance of GBM cells. The present study addresses the mechanisms leading to the excessive cell membrane area in five GBM lines differing in mutational status for PTEN and p53. In addition to scanning electron microscopy (SEM, the membrane area and folding were quantified by dielectric measurements of membrane capacitance using the single-cell electrorotation (ROT technique. The osmotic stability and volume regulation of GBM cells were analyzed by video microscopy. The expression of PTEN, p53, mTOR and several other marker proteins involved in cell growth and membrane synthesis were examined by Western blotting. The combined SEM, ROT and osmotic data provided independent lines of evidence for a large variability in membrane area and folding among tested GBM lines. Thus, DK-MG cells (wild type p53 and wild type PTEN exhibited the lowest degree of membrane folding, probed by the area-specific capacitance C m = 1.9 µF/cm(2. In contrast, cell lines carrying mutations in both p53 and PTEN (U373-MG and SNB19 showed the highest C m values of 3.7-4.0 µF/cm(2, which corroborate well with their heavily villated cell surface revealed by SEM. Since PTEN and p53 are well-known inhibitors of mTOR, the increased membrane area/folding in mutant GBM lines may be related to the enhanced protein and lipid synthesis due to a deregulation of the mTOR-dependent downstream signaling pathway. Given that membrane folds and extensions are implicated in tumor cell motility and metastasis, the dielectric approach presented here provides a rapid and simple tool for screening the biophysical cell properties in studies on targeting chemo- or radiotherapeutically the

  5. Wildtype p53-specific Antibody and T-Cell Responses in Cancer Patients

    DEFF Research Database (Denmark)

    Pedersen, Anders Elm; Stryhn, Anette; Justesen, Sune

    2011-01-01

    patients. Detection of antibodies against wt p53 protein has been used as a diagnostic and prognostic marker and discovery of new T-cell epitopes has enabled design of cancer vaccination protocols with promising results. Here, we identified wt p53-specific antibodies in various cancer patients......(264-272) in breast cancer patients and against HLA-A*01:01 binding peptide wt p53(226-234) and HLA-B*07:02 binding peptide wt p53(74-82) in renal cell cancer and breast cancer patients, respectively. Finally, we analyzed antibody and T-cell responses against wt p53 15-mer peptides in patients with metastatic renal...

  6. CD40-mediated apoptosis in murine B-lymphoma lines containing mutated p53

    DEFF Research Database (Denmark)

    Hollmann, Annette C; Gong, Qiaoke; Owens, Trevor

    2002-01-01

    Crosslinking CD40 induces normal B-cells to proliferate and differentiate but causes many tumor cell lines to undergo apoptosis. As p53 is required for many apoptotic pathways, we analyzed the effects of CD40 ligation and their correlation with p53 function in four murine B-lymphoma lines. A20...... of detectable p21 mRNA in A20 and M12 cells. P21 mRNA was increased to detectable levels in M12 cells upon CD40 ligation; however, blocking this effect with the p53 inhibitor pifithrin had no effect on CD40-mediated apoptosis. Sequencing showed that p53 in A20 and M12 cells contained point mutations leading...... to amino acid substitutions in DNA binding regions, but was unmutated in WEHI231 and WEHI 279. These results suggest that CD40-mediated apoptosis can occur in the absence of functional p53....

  7. HER-2 positive and p53 negative breast cancers are associated with poor prognosis.

    LENUS (Irish Health Repository)

    2011-06-01

    p53 and HER-2 coexpression in breast cancer has been controversial. These markers were tested using immunohistochemistry and HercepTest. HER-2 expression is related to reduced breast cancer survival (p = .02) . p53 expression relates to HER-2 expression (p = .029). Coexpression between p53 and HER-2 has no relation to prognosis. On univariate and multivariate analysis, combination of HER-2 positive and p53 negative expression was associated with a poor prognosis (p = .018 and p = .027, respectively), while the combination of HER-2 negative and p53 positive expression was associated with a favorable prognosis (p = .022 and p = .010, respectively). Therefore the expression of these markers should be considered collectively.

  8. 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.

  9. ZNF307, a novel zinc finger gene suppresses p53 and p21 pathway

    International Nuclear Information System (INIS)

    Li Jing; Wang Yuequn; Fan Xiongwei; Mo Xiaoyang; Wang Zequn; Li Yongqing; Yin Zhaochu; Deng Yun; Luo Na; Zhu Chuanbing; Liu Mingyao; Ma Qian; Ocorr, Karen; Yuan Wuzhou; Wu Xiushan

    2007-01-01

    We have cloned a novel KRAB-related zinc finger gene, ZNF307, encoding a protein of 545 aa. ZNF307 is conserved across species in evolution and is differentially expressed in human adult and fetal tissues. The fusion protein of EGFP-ZNF307 localizes in the nucleus. Transcriptional activity assays show ZNF307 suppresses transcriptional activity of L8G5-luciferase. Overexpressing ZNF307 in different cell lines also inhibits the transcriptional activities of p53 and p21. Moreover, ZNF307 works by reducing the p53 protein level and p53 protein reduction is achieved by increasing transcription of MDM2 and EP300. ZNF307 might suppress p53-p21 pathway through activating MDM2 and EP300 expression and inducing p53 degradation

  10. HER-2 positive and p53 negative breast cancers are associated with poor prognosis.

    LENUS (Irish Health Repository)

    2012-02-01

    p53 and HER-2 coexpression in breast cancer has been controversial. These markers were tested using immunohistochemistry and HercepTest. HER-2 expression is related to reduced breast cancer survival (p = .02) . p53 expression relates to HER-2 expression (p = .029). Coexpression between p53 and HER-2 has no relation to prognosis. On univariate and multivariate analysis, combination of HER-2 positive and p53 negative expression was associated with a poor prognosis (p = .018 and p = .027, respectively), while the combination of HER-2 negative and p53 positive expression was associated with a favorable prognosis (p = .022 and p = .010, respectively). Therefore the expression of these markers should be considered collectively.

  11. p53 functions as a cell cycle control protein in osteosarcomas.

    Science.gov (United States)

    Diller, L; Kassel, J; Nelson, C E; Gryka, M A; Litwak, G; Gebhardt, M; Bressac, B; Ozturk, M; Baker, S J; Vogelstein, B

    1990-11-01

    Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfected cells to progress into S phase. This suggests that the role of the p53 gene as an antioncogene may be in controlling the cell cycle in a fashion analogous to the check-point control genes in Saccharomyces cerevisiae.

  12. p53 functions as a cell cycle control protein in osteosarcomas.

    Science.gov (United States)

    Diller, L; Kassel, J; Nelson, C E; Gryka, M A; Litwak, G; Gebhardt, M; Bressac, B; Ozturk, M; Baker, S J; Vogelstein, B

    1990-01-01

    Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfected cells to progress into S phase. This suggests that the role of the p53 gene as an antioncogene may be in controlling the cell cycle in a fashion analogous to the check-point control genes in Saccharomyces cerevisiae. Images PMID:2233717

  13. Endogenous c-Myc is essential for p53-induced apoptosis in response to DNA damage in vivo.

    Science.gov (United States)

    Phesse, T J; Myant, K B; Cole, A M; Ridgway, R A; Pearson, H; Muncan, V; van den Brink, G R; Vousden, K H; Sears, R; Vassilev, L T; Clarke, A R; Sansom, O J

    2014-06-01

    Recent studies have suggested that C-MYC may be an excellent therapeutic cancer target and a number of new agents targeting C-MYC are in preclinical development. Given most therapeutic regimes would combine C-MYC inhibition with genotoxic damage, it is important to assess the importance of C-MYC function for DNA damage signalling in vivo. In this study, we have conditionally deleted the c-Myc gene in the adult murine intestine and investigated the apoptotic response of intestinal enterocytes to DNA damage. Remarkably, c-Myc deletion completely abrogated the immediate wave of apoptosis following both ionizing irradiation and cisplatin treatment, recapitulating the phenotype of p53 deficiency in the intestine. Consistent with this, c-Myc-deficient intestinal enterocytes did not upregulate p53. Mechanistically, this was linked to an upregulation of the E3 Ubiquitin ligase Mdm2, which targets p53 for degradation in c-Myc-deficient intestinal enterocytes. Further, low level overexpression of c-Myc, which does not impact on basal levels of apoptosis, elicited sustained apoptosis in response to DNA damage, suggesting c-Myc activity acts as a crucial cell survival rheostat following DNA damage. We also identify the importance of MYC during DNA damage-induced apoptosis in several other tissues, including the thymus and spleen, using systemic deletion of c-Myc throughout the adult mouse. Together, we have elucidated for the first time in vivo an essential role for endogenous c-Myc in signalling DNA damage-induced apoptosis through the control of the p53 tumour suppressor protein.