Overexpression of p53, MDM2 proteins in some atr radiation-induced skin ulcers

International Nuclear Information System (INIS)

Gu Qingyang; Gao Yabing; Wang Dewen; Cui Yufang; Zhao Po; Yang Zhixiang; Zhou Jie

2000-01-01

An animal model of radiation-induced skin ulcer was set up with 140 rats, which were locally irradiated with 35-55 Gy γ-rays. The pathological changes were observed for 1 year. Immunohistochemical studies were performed in 72 rat radiation skin ulcer specimens using anti-p53 and anti-MDM2 proteins polyclonal antibodies. The results showed that the positive rate for overexpression of p53 protein was 9.7%, and for that of MDM2 was 19.4%. The overexpression of p53 was mainly seen in the nuclei of activated squamous epithelial cells, and in fibroblasts, endotheliocytes in deeper part of the skin ulcers. The overexpression of MDM2 had the same localizations. It is suggested that the changes of p53 and MDM2, genes and proteins, may be related to the cancer transformation and poor healing of radiation-induced skin ulcers

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

The prognostic value of p53 mutation in pediatric marrow hypoplasia

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Sharaf Alzahraa EA

2011-06-01

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

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.

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...

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.

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

The p16INK4alpha/p19ARF gene mutations are infrequent and are mutually exclusive to p53 mutations in Indian oral squamous cell carcinomas.

Science.gov (United States)

Kannan, K; Munirajan, A K; Krishnamurthy, J; Bhuvarahamurthy, V; Mohanprasad, B K; Panishankar, K H; Tsuchida, N; Shanmugam, G

2000-03-01

Eighty-seven untreated primary oral squamous cell carcinomas (SCCs) associated with betel quid and tobacco chewing from Indian patients were analysed for the presence of mutations in the commonly shared exon 2 of p16INK4alpha/p19ARF genes. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing analysis were used to detect mutations. SSCP analysis indicated that only 9% (8/87) of the tumours had mutation in p16INK4alpha/p19ARF genes. Seventy-two tumours studied here were previously analysed for p53 mutations and 21% (15/72) of them were found to have mutations in p53 gene. Only one tumour was found to have mutation at both p53 and p16INK4alpha/p19ARF genes. Thus, the mutation rates observed were 21% for p53, 9% for p16INK4alpha/p19ARF, and 1% for both. Sequencing analysis revealed two types of mutations; i) G to C (GCAG to CCAG) transversion type mutation at intron 1-exon 2 splice junction and ii) another C to T transition type mutation resulting in CGA to TGA changing arginine to a termination codon at p16INK4alpha gene codon 80 and the same mutation will alter codon 94 of p19ARF gene from CCG to CTG (proline to leucine). These results suggest that p16INK4alpha/p19ARF mutations are less frequent than p53 mutations in Indian oral SCCs. The p53 and p16INK4alpha/p19ARF mutational events are independent and are mutually exclusive suggesting that mutational inactivation of either p53 or p16INK4alpha/p19ARF may alleviate the need for the inactivation of the other gene.

Prognostic implications of molecular and immunohistochemical profiles of the Rb and p53 cell cycle regulatory pathways in primary non-small cell lung carcinoma.

LENUS (Irish Health Repository)

Burke, Louise

2012-02-03

PURPOSE: Many studies have highlighted the aberrant expression and prognostic significance of individual proteins in either the Rb (particularly cyclin D1, p16INK4A, and pRb) or the p53 (p53 and p21Waf1) pathways in non-small cell lung cancer. We hypothesize that cumulative abnormalities within each and between these pathways would have significant prognostic potential regarding survival. EXPERIMENTAL DESIGN: Our study population consisted of 106 consecutive surgically resected cases of predominantly early-stage non-small cell lung cancer from the National Cancer Institute-Mayo Clinic series, and assessment of proteins involved both immunohistochemical (cyclin D1, p21Waf1, pRb, p16INK4A, and p53) and mutational analysis (p53) in relationship to staging and survival. RESULTS: Cyclin D1 overexpression was noted in 48% of the tumors, p16INK4A negative in 53%, pRb negative in 17%, p53 immunopositive in 50%, p53 mutation frequency in 48%, and p21(Waf1) overexpression in 47%, none with prognostic significance. Cyclin D1 overexpression in pRb-negative tumors revealed a significantly worse prognosis with a mean survival of 2.3 years (P = 0.004). A simultaneous p53 mutation dramatically reduced the mean survival time to 0.9 years (P = 0.007). Cyclin D1 overexpression with either a p53 mutation or a p53 overexpression was also associated with a significantly poorer prognosis (P = 0.0033 and 0.0063, respectively). CONCLUSIONS: Some cumulative abnormalities in the Rb and p53 pathways (e.g., cyclin D1 overexpression and p53 mutations) significantly cooperate to predict a poor prognosis; however, the complexity of the cell cycle protein interaction in any given tumor warrants caution in interpreting survival results when specific protein abnormalities are taken in isolation.

Significance of Aurora B overexpression in hepatocellular carcinoma. Aurora B Overexpression in HCC

International Nuclear Information System (INIS)

Lin, Zhong-Zhe; Jeng, Yung-Ming; Hu, Fu-Chang; Pan, Hung-Wei; Tsao, Hsin-Wei; Lai, Po-Lin; Lee, Po-Huang; Cheng, Ann-Lii; Hsu, Hey-Chi

2010-01-01

To investigate the significance of Aurora B expression in hepatocellular carcinoma (HCC). The Aurora B and Aurora A mRNA level was measured in 160 HCCs and the paired nontumorous liver tissues by reverse transcription-polymerase chain reaction. Mutations of the p53 and β-catenin genes were analyzed in 134 and 150 tumors, respectively, by direct sequencing of exon 2 to exon 11 of p53 and exon 3 of β-catenin. Anticancer effects of AZD1152-HQPA, an Aurora B kinase selective inhibitor, were examined in Huh-7 and Hep3B cell lines. Aurora B was overexpressed in 98 (61%) of 160 HCCs and in all 7 HCC cell lines examined. The overexpression of Aurora B was associated with Aurora A overexpression (P = 0.0003) and p53 mutation (P = 0.002) and was inversely associated with β-catenin mutation (P = 0.002). Aurora B overexpression correlated with worse clinicopathologic characteristics. Multivariate analysis confirmed that Aurora B overexpression was an independent poor prognostic factor, despite its interaction with Aurora A overexpression and mutations of p53 and β-catenin. In Huh-7 and Hep3B cells, AZD1152-HQPA induced proliferation blockade, histone H3 (Ser10) dephosphorylation, cell cycle disturbance, and apoptosis. Aurora B overexpression is an independent molecular marker predicting tumor invasiveness and poor prognosis of HCC. Aurora B kinase selective inhibitors are potential therapeutic agents for HCC treatment

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.

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

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-...

No evidence for functional inactivation of wild-type p53 protein by MDM2 overexpression in gastric carcinogenesis

NARCIS (Netherlands)

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

1998-01-01

Inactivation of wild-type p53 during gastric carcinogenesis is usually caused by mutations within exons 5-8 of the p53 gene leading to mutated, usually immunohistochemically detectable p53 proteins. However, functional inactivation of wild-type p53, mimicking mutational inactivation, may also result

Low Prevalence of TP53 Mutations and MDM2 Amplifications in Pediatric Rhabdomyosarcoma

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Simona Ognjanovic

2012-01-01

Full Text Available The tumor suppressor gene TP53 is the most commonly mutated gene in human cancer. The reported prevalence of mutations in rhabdomyosarcoma (RMS varies widely, with recent larger studies suggesting that TP53 mutations in pediatric RMS may be extremely rare. Overexpression of MDM2 also attenuates p53 function. We have performed TP53 mutation/MDM2 amplification analyses in the largest series analyzed thus far, including DNA isolated from 37 alveolar and 38 embryonal RMS tumor samples obtained from the Cooperative Human Tissue Network (CHTN. Available samples were frozen tumor tissues (N=48 and histopathology slides. TP53 mutations in exons 4–9 were analyzed by direct sequencing in all samples, and MDM2 amplification analysis was performed by differential PCR on a subset of 22 samples. We found only one sample (1/75, 1.3% carrying a TP53 mutation at codon 259 (p.D259Y and no MDM2 amplification. Two SNPs in the TP53 pathway, associated with accelerated tumor onset in germline TP53 mutation carriers, (TP53 SNP72 (rs no. 1042522 and MDM2 SNP309 (rs no. 2279744, were not found to confer earlier tumor onset. In conclusion, we confirm the extremely low prevalence of TP53 mutations/MDM2 amplifications in pediatric RMS (1.33% and 0%, respectively. The possible inactivation of p53 function by other mechanisms thus remains to be elucidated.

Overexpression of phosphomimic mutated OsWRKY53 leads to enhanced blast resistance in rice.

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Tetsuya Chujo

Full Text Available WRKY transcription factors and mitogen-activated protein kinase (MAPK cascades have been shown to play pivotal roles in the regulation of plant defense responses. We previously reported that OsWRKY53-overexpressing rice plants showed enhanced resistance to the rice blast fungus. In this study, we identified OsWRKY53 as a substrate of OsMPK3/OsMPK6, components of a fungal PAMP-responsive MAPK cascade in rice, and analyzed the effect of OsWRKY53 phosphorylation on the regulation of basal defense responses to a virulence race of rice blast fungus Magnaporthe oryzae strain Ina86-137. An in vitro phosphorylation assay revealed that the OsMPK3/OsMPK6 activated by OsMKK4 phosphorylated OsWRKY53 recombinant protein at its multiple clustered serine-proline residues (SP cluster. When OsWRKY53 was coexpressed with a constitutively active mutant of OsMKK4 in a transient reporter gene assay, the enhanced transactivation activity of OsWRKY53 was found to be dependent on phosphorylation of the SP cluster. Transgenic rice plants overexpressing a phospho-mimic mutant of OsWRKY53 (OsWRKY53SD showed further-enhanced disease resistance to the blast fungus compared to native OsWRKY53-overexpressing rice plants, and a substantial number of defense-related genes, including pathogenesis-related protein genes, were more upregulated in the OsWRKY53SD-overexpressing plants compared to the OsWRKY53-overexpressing plants. These results strongly suggest that the OsMKK4-OsMPK3/OsMPK6 cascade regulates transactivation activity of OsWRKY53, and overexpression of the phospho-mimic mutant of OsWRKY53 results in a major change to the rice transcriptome at steady state that leads to activation of a defense response against the blast fungus in rice plants.

Overexpression of Phosphomimic Mutated OsWRKY53 Leads to Enhanced Blast Resistance in Rice

Science.gov (United States)

Ogawa, Satoshi; Masuda, Yuka; Shimizu, Takafumi; Kishi-Kaboshi, Mitsuko; Takahashi, Akira; Nishizawa, Yoko; Minami, Eiichi; Nojiri, Hideaki; Yamane, Hisakazu; Okada, Kazunori

2014-01-01

WRKY transcription factors and mitogen-activated protein kinase (MAPK) cascades have been shown to play pivotal roles in the regulation of plant defense responses. We previously reported that OsWRKY53-overexpressing rice plants showed enhanced resistance to the rice blast fungus. In this study, we identified OsWRKY53 as a substrate of OsMPK3/OsMPK6, components of a fungal PAMP-responsive MAPK cascade in rice, and analyzed the effect of OsWRKY53 phosphorylation on the regulation of basal defense responses to a virulence race of rice blast fungus Magnaporthe oryzae strain Ina86-137. An in vitro phosphorylation assay revealed that the OsMPK3/OsMPK6 activated by OsMKK4 phosphorylated OsWRKY53 recombinant protein at its multiple clustered serine-proline residues (SP cluster). When OsWRKY53 was coexpressed with a constitutively active mutant of OsMKK4 in a transient reporter gene assay, the enhanced transactivation activity of OsWRKY53 was found to be dependent on phosphorylation of the SP cluster. Transgenic rice plants overexpressing a phospho-mimic mutant of OsWRKY53 (OsWRKY53SD) showed further-enhanced disease resistance to the blast fungus compared to native OsWRKY53-overexpressing rice plants, and a substantial number of defense-related genes, including pathogenesis-related protein genes, were more upregulated in the OsWRKY53SD-overexpressing plants compared to the OsWRKY53-overexpressing plants. These results strongly suggest that the OsMKK4-OsMPK3/OsMPK6 cascade regulates transactivation activity of OsWRKY53, and overexpression of the phospho-mimic mutant of OsWRKY53 results in a major change to the rice transcriptome at steady state that leads to activation of a defense response against the blast fungus in rice plants. PMID:24892523

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

Science.gov (United States)

Romano, Rose-Anne; Sinha, Satrajit

2014-04-01

The p53 family (p53, p63 and p73) is intimately linked with an overwhelming number of cellular processes during normal physiological as well as pathological conditions including cancer. The fact that these proteins are expressed in myriad isoforms, each with unique biochemical properties and distinct effects on tumorigenesis, complicates their study. A case in point is Squamous Cell Carcinoma (SCC) where p53 is often mutated and the ΔNp63 isoform is overexpressed. Given that p53 and p63 can hetero-dimerize, bind to quite similar DNA elements and share common co-factors, any alterations in their individual expression levels, activity and/or mutation can severely disrupt the family equilibrium. The burgeoning genomics data sets and new additions to the experimental toolbox are offering crucial insights into the complex role of the p53 family in SCC, but more mechanistic studies are needed. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

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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.

Detection of p53 gene mutations in bronchial biopsy samples of patients with lung cancer

International Nuclear Information System (INIS)

Irshad, S.; Nawaz, T.

2008-01-01

Lung cancer is the malignant transformation and expansion of lung tissue. It is the most lethal of all cancers worldwide, responsible for 1.2 million deaths annually. The goal of this study was to detect the p53 gene mutations in lung cancer, in local population of Lahore, Pakistan. These mutations were screened in the bronchial biopsy lung cancer tissue samples. For this purpose microtomed tissue sections were collected. Following DNA extraction from tissue sections, the p53 mutations were detected by amplifying Exon 7 (145 bp) and Exon 8 (152 bp) of the p53 gene. PCR then followed by single-strand conformation polymorphism analysis for screening the p53 gene mutations. This results of SSCP were visualized of silver staining. The results showed different banding pattern indicating the presence of mutation. Majority of the mutations were found in Exon 7. Exon 7 of p53 gene may be the mutation hotspot in lung cancer. In lung cancer, the most prevalent mutations of p53 gene are G -> T transversions; other types of insertions and deletions are also expected, however, the exact nature of mutations in presented work could be confirmed by direct sequencing. (author)

Overexpression of 15-lipoxygenase-1 induces growth arrest through phosphorylation of p53 in human colorectal cancer cells.

Science.gov (United States)

Kim, Jong-Sik; Baek, Seung Joon; Bottone, Frank G; Sali, Tina; Eling, Thomas E

2005-09-01

To investigate the function of 15-lipoxygenase-1 (15-LOX-1) in human colorectal cancer, we overexpressed 15-LOX-1 in HCT-116 human colorectal cancer cells. Clones expressing the highest levels of 15-LOX-1 displayed reduced viability compared with the HCT-116-Vector control cells. Further, by cell cycle gene array analyses, the cyclin-dependent kinase inhibitor p21WAF1/CIP1 and MDM2 genes were up-regulated in 15-LOX-1-overexpressing cells. The induction of p21(WAF1/CIP1) and MDM2 were linked to activation of p53 by 15-LOX-1, as there was a dramatic induction of phosphorylated p53 (Ser15) in 15-LOX-1-overesxpressing cells. However, the 15-LOX-1 metabolites 13(S)-hydroxyoctadecadienoic acid and 15(S)-hydroxyeicosatetraenoic acid failed to induce phosphorylation of p53 at Ser15, and the 15-LOX-1 inhibitor PD146176 did not inhibit the phosphorylation of p53 at Ser15 in 15-LOX-1-overexpressing cells. Nonetheless, the growth-inhibitory effects of 15-LOX-1 were p53 dependent, as 15-LOX-1 overexpression had no effect on cell growth in p53 (-/-) HCT-116 cells. Finally, treatment of HCT-116-15-LOX-1 cells with different kinase inhibitors suggested that the effects of 15-LOX-1 on p53 phosphorylation and activation were due to effects on DNA-dependent protein kinase. Collectively, these findings suggest a new mechanism to explain the biological activity of 15-LOX-1, where 15-LOX plays a stoichiometric role in activating a DNA-dependent protein kinase-dependent pathway that leads to p53-dependent growth arrest.

Chemical Variations on the p53 Reactivation Theme

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Carlos J. A. Ribeiro

2016-05-01

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

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...

Relationship between p53 dysfunction, CD38 expression, and IgV(H) mutation in chronic lymphocytic leukemia.

Science.gov (United States)

Lin, Ke; Sherrington, Paul D; Dennis, Michael; Matrai, Zoltan; Cawley, John C; Pettitt, Andrew R

2002-08-15

Established adverse prognostic factors in chronic lymphocytic leukemia (CLL) include CD38 expression, relative lack of IgV(H) mutation, and defects of the TP53 gene. However, disruption of the p53 pathway can occur through mechanisms other than TP53 mutation, and we have recently developed a simple screening test that detects p53 dysfunction due to mutation of the genes encoding either p53 or ATM, a kinase that regulates p53. The present study was conducted to examine the predictive value of this test and to establish the relationship between p53 dysfunction, CD38 expression, and IgV(H) mutation. CLL cells from 71 patients were examined for IgV(H) mutation, CD38 expression, and p53 dysfunction (detected as an impaired p53/p21 response to ionizing radiation). Survival data obtained from 69 patients were analyzed according to each of these parameters. Relative lack of IgV(H) mutation (less than 5%; n = 45), CD38 positivity (antigen expressed on more than 20% of malignant cells; n = 19), and p53 dysfunction (n = 19) were independently confirmed as adverse prognostic factors. Intriguingly, all p53-dysfunctional patients and all but one of the CD38(+) patients had less [corrected] than 5% IgV(H) mutation. Moreover, patients with p53 dysfunction and/or CD38 positivity (n = 31) accounted for the short survival of the less mutated group. These findings indicate that the poor outcome associated with having less than 5% IgV(H) mutation may be due to the overrepresentation of high-risk patients with p53 dysfunction and/or CD38 positivity within this group, and that CD38(-) patients with functionally intact p53 may have a prolonged survival regardless of the extent of IgV(H) mutation.

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.

Concurrent overexpression of serum p53 mutation related with Helicobacter pylori infection

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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.

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

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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.

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

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

2015-09-01

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

Profiling of oligosaccharides and p53 gene mutation in Filipino breast tumors

International Nuclear Information System (INIS)

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

2010-01-01

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

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

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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.

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

NARCIS (Netherlands)

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

1993-01-01

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

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

High Resolution Melting Analysis for Detecting p53 Gene Mutations in Patients with Non-small Cell Lung Cancer

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Zhihong CHEN

2011-10-01

Full Text Available Background and objective It has been proven that p53 gene was related to many human cancers. The mutations in p53 gene play an important role in carcinogensis and mostly happened in exon 5-8. The aim of this study is to establish a high resolution melting (HRM assay to detect p53 mutations from patients with non-small cell lung cancer (NSCLC, to investigate the characteristics of p53 gene mutations, and to analyze the relationship between p53 mutations and evolution regularity of pathogenesis. Methods p53 mutations in exon 5-8 were detected by HRM assay on DNA insolated from 264 NSCLC samples derived from tumor tissues and 54 control samples from pericancerous pulmonary tissues. The mutation samples by the HRM assay were confirmed by sequencing technique. Samples which were positive by HRM but wild type by sequencing were further confirmed by sub-clone and sequencing. Results No mutation was found in 54 pericancerous pulmonary samples by HRM assay. 104 of the 264 tumor tissues demonstrated mutation curves by HRM assay, 102 samples were confirmed by sequencing, including 95 point mutations and 7 frame shift mutations by insertion or deletion. The mutation rate of p53 gene was 39.4%. The mutation rate from exon 5-8 were 11.7%, 8%, 12.5% and 10.6%, respectively and there was no statistically significant difference between them (P=0.35. p53 mutations were significantly more frequent in males than that in females, but not related to the other clinicopathologic characteristics. Conclusion The results indicate that HRM is a sensitive in-tube methodology to detect for mutations in clinical samples. The results suggest that the arising p53 mutations in NSCLC may be due to spontaneous error in DNA synthesis and repair.

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

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Kumari Ratna

2010-07-01

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

Rapid detection of single nucleotide mutation in p53 gene based on ...

Indian Academy of Sciences (India)

mutation.27 Nevertheless, more than 50% of all human tumors contain p53 mutation; ... gene mutation detection in various fields of biology and medicine persuaded us to find ..... Yola M L, Eren T and Atar N 2014 Electrochim. Acta. 125 38. 26.

THE EXON 5, 6, 7, 8 OF P53 MUTATIONS IN ORAL SQUAMOUS CELLS CARCINOMA

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Retno P Rahayu

2012-04-01

Full Text Available Genetic instability may underlie the etiology of multistep carcinogenesis. The altered p53 gene observed in tumors may represent the expression of such instability and may allow the accumulation of other gene alterations caused by multiple mechanism. p53 gene is the guardian of the genome, that is why we pay more attention to this gene. In this study, we evaluated the significance of p53 mutation in 55 patient with oral squamous carcinoma. Thirty among them underwent well-differentiated carcinoma, while the remaining 25 patients underwent poorly differentiated carcinoma. The mutations were detected by PCR-SSCP (Single strand Conformational Polymorphism analysis in the region between exon 5 and exon 8. The results indicated that the p53 mutation in exon 5 (40%, exon 6 (28%, exon 7 (24% and exon 8 (8% were associated with poorly differentiated carcinoma, whereas mutation in exon 5 (10%, exon 6 (30%, exon 7 (40% and exon 8 (20% were associated with well-differentiated carcinoma. These observations suggest that p53 mutation in exon 5, 6, and 7 have strong correlation with poorly differentiated in oral squamous carcinoma while well-differentiated level was related with mutation in exon 6,7 and 8.

Low-level overexpression of p53 promotes warfarin-induced calcification of porcine aortic valve interstitial cells by activating Slug gene transcription.

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Gao, Li; Ji, Yue; Lu, Yan; Qiu, Ming; Shen, Yejiao; Wang, Yaqing; Kong, Xiangqing; Shao, Yongfeng; Sheng, Yanhui; Sun, Wei

2018-03-09

The most frequently used oral anti-coagulant warfarin has been implicated in inducing calcification of aortic valve interstitial cells (AVICs), whereas the mechanism is not fully understood. The low-level activation of p53 is found to be involved in osteogenic transdifferentiation and calcification of AVICs. Whether p53 participates in warfarin-induced AVIC calcification remains unknown. In this study, we investigated the role of low-level p53 overexpression in warfarin-induced porcine AVIC (pAVIC) calcification. Immunostaining, quantitative PCR, and Western blotting revealed that p53 was expressed in human and pAVICs and that p53 expression was slightly increased in calcific human aortic valves compared with non-calcific valves. Terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling staining indicated that apoptosis slightly increased in calcific aortic valves than in non-calcific valves. Warfarin treatment led to a low-level increase of p53 mRNA and protein in both pAVICs and mouse aortic valves. Low-level overexpression of p53 in pAVICs via an adenovirus vector did not affect pAVIC apoptosis but promoted warfarin-induced calcium deposition and expression of osteogenic markers. shRNA-mediated p53 knockdown attenuated the pAVIC calcium deposition and osteogenic marker expression. Moreover, ChIP and luciferase assays showed that p53 was recruited to the slug promoter and activated slug expression in calcific pAVICs. Of note, overexpression of Slug increased osteogenic marker Runx2 expression, but not pAVIC calcium deposition, and Slug knockdown attenuated pAVIC calcification and p53-mediated pAVIC calcium deposition and expression of osteogenic markers. In conclusion, we found that p53 plays an important role in warfarin induced pAVIC calcification, and increased slug transcription by p53 is required for p53-mediated pAVIC calcification. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

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

Science.gov (United States)

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

1997-12-01

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

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

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

1994-09-01

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

MDM2 SNP309 promoter polymorphism and p53 mutations in urinary bladder carcinoma stage T1

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Olsson Hans

2013-01-01

Full Text Available Abstract Background Urinary bladder carcinoma stage T1 is an unpredictable disease that in some cases has a good prognosis with only local or no recurrence, but in others can appear as a more aggressive tumor with progression to more advanced stages. The aim here was to investigate stage T1 tumors regarding MDM2 promoter SNP309 polymorphism, mutations in the p53 gene, and expression of p53 and p16 measured by immunohistochemistry, and subsequently relate these changes to tumor recurrence and progression. We examined a cohort of patients with primary stage T1 urothelial carcinoma of the bladder and their tumors. Methods After re-evaluation of the original slides and exclusions, the study population comprised 141 patients, all with primary stage T1 urothelial carcinoma of the bladder. The hospital records were screened for clinical parameters and information concerning presence of histologically proven recurrence and progression. The paraffin-embedded tumor material was evaluated by immunohistochemistry. Any mutations found in the p53 gene were studied by single-strand conformation analysis and Sanger sequencing. The MDM2 SNP309 polymorphism was investigated by pyrosequencing. Multivariate analyses concerning association with prognosis were performed, and Kaplan-Meier analysis was conducted for a combination of changes and time to progression. Results Of the 141 patients, 82 had at least one MDM2 SNP309 G allele, and 53 had a mutation in the p53 gene, but neither of those anomalies was associated with a worse prognosis. A mutation in the p53 gene was associated with immunohistochemically visualized p53 protein expression at a cut-off value of 50%. In the group with p53 mutation Kaplan-Meier analysis showed higher rate of progression and shorter time to progression in patients with immunohistochemically abnormal p16 expression compared to them with normal p16 expression (p = 0.038. Conclusions MDM2 SNP309 promoter polymorphism and mutations in

Analysis of p53- immunoreactivity in astrocytic brain tumors

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Shinkarenko T.V.

2016-12-01

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

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.

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

Expression of p53, MDM2 in a mice hydradecarcinoma model induced by γ-ray irradiation

International Nuclear Information System (INIS)

Huang Yuecheng; Cai Jianming; Han Ling; Gao Fu; Sun Ding; Dong Zhitao; Zhe Wanli

2004-01-01

Objective: To investigate the role of the p53, MDM2 in carcinogenesis of mice hydradecarcinoma induced by γ-rays. Methods: A radiation-induced mice hydradecarcinoma model was established by γ-ray irradiation. Expression of MDM2 protein in hydradecarcinoma tissue, paracancerous tissue and normal control tissue was detected with Western blot. Immunoprecipitation (IP) was conducted to examine the phosphorylation level of MDM2 protein. PCR-SSCP was performed to detect p53 gene mutation. Results: Compared with the normal control tissue, the MDM2 protein expression and its phosphorylation level were significantly higher in hydradecarcinoma tissue. SSCP showed there were p53 gene mutations in hydradecarcinoma samples. Conclusion: p53/MDM2 pathway may be involved in the development and progression of hydradecarcinoma induced by γ-ray irradiation. The over-expression of MDM2 and hyperphosphorylation may be responsible for malignant transformation induced by irradiation by a possible mechanism of p53 inactivation. The gene mutation of p53 further supported the hypothesis that p53/MDM2 pathway played a central role in carcinogenesis of γray induced hydradecarcinoma. (authors)

Prognostic value of p53 mutations in patients with locally advanced esophageal carcinoma treated with definitive chemoradiotherapy

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Ito, Tomohiro; Kaneko, Kazuhiro; Makino, Reiko; Ito, Hiroaki; Konishi, Kazuo; Kurahashi, Toshinori; Kitahara, Tadashi; Mitamura, Keiji [Showa Univ., Tokyo (Japan). School of Medicine

2001-05-01

A significant correlation has been found between p53 mutation and response to chemotherapy or radiotherapy. To determine the prognostic value of p53 mutation in patients with locally advanced esophageal carcinoma treated with definitive chemoradiotherapy, p53 mutation was analyzed using the biopsied specimens taken for diagnosis. Concurrent chemoradiotherapy was performed for 40 patients with severe dysphagia caused by esophageal squamous cell carcinoma associated with T3 or T4 disease. Chemotherapy consisted of protracted infusion of 5-fluorouracil, combined with an infusion of cisplatinum. Radiation treatment of the mediastinum was administered concomitantly with chemotherapy. The p53 gene mutation was detected by fluorescence-based polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) methods. DNA sequences were determined for DNA fragments with shifted peaks by SSCP methods. Of the 40 patients, 15 had T3 disease and 25 had T4 disease; 11 patients had M1 lymph node (LYM) disease. Of the 40 patients, 13 (33%) achieved a complete response. The median survival time was 14 months, and the 2-year survival rate was 20%. Among the 40 tumor samples, p53 mutation was detected in 24 tumors (60%). The survival rate in the 24 patients with p53 mutation did not differ significantly from that in the 16 patients without p53 mutation. In contrast, the 15 patients with T3 disease survived longer than the 25 patients with T4 disease (P=0.016); however, the survival rate in the 11 patients with M1 LYM disease did not differ significantly from that in the 29 patients without M1 LYM disease. Concurrent chemoradiotherapy is potentially curative for locally advanced esophageal carcinoma, but p53 genetic abnormality has no impact on prognosis. (author)

Prognostic value of p53 mutations in patients with locally advanced esophageal carcinoma treated with definitive chemoradiotherapy

International Nuclear Information System (INIS)

Ito, Tomohiro; Kaneko, Kazuhiro; Makino, Reiko; Ito, Hiroaki; Konishi, Kazuo; Kurahashi, Toshinori; Kitahara, Tadashi; Mitamura, Keiji

2001-01-01

A significant correlation has been found between p53 mutation and response to chemotherapy or radiotherapy. To determine the prognostic value of p53 mutation in patients with locally advanced esophageal carcinoma treated with definitive chemoradiotherapy, p53 mutation was analyzed using the biopsied specimens taken for diagnosis. Concurrent chemoradiotherapy was performed for 40 patients with severe dysphagia caused by esophageal squamous cell carcinoma associated with T3 or T4 disease. Chemotherapy consisted of protracted infusion of 5-fluorouracil, combined with an infusion of cisplatinum. Radiation treatment of the mediastinum was administered concomitantly with chemotherapy. The p53 gene mutation was detected by fluorescence-based polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) methods. DNA sequences were determined for DNA fragments with shifted peaks by SSCP methods. Of the 40 patients, 15 had T3 disease and 25 had T4 disease; 11 patients had M1 lymph node (LYM) disease. Of the 40 patients, 13 (33%) achieved a complete response. The median survival time was 14 months, and the 2-year survival rate was 20%. Among the 40 tumor samples, p53 mutation was detected in 24 tumors (60%). The survival rate in the 24 patients with p53 mutation did not differ significantly from that in the 16 patients without p53 mutation. In contrast, the 15 patients with T3 disease survived longer than the 25 patients with T4 disease (P=0.016); however, the survival rate in the 11 patients with M1 LYM disease did not differ significantly from that in the 29 patients without M1 LYM disease. Concurrent chemoradiotherapy is potentially curative for locally advanced esophageal carcinoma, but p53 genetic abnormality has no impact on prognosis. (author)

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.

Missense mutations located in structural p53 DNA-binding motifs are associated with extremely poor survival in chronic lymphocytic leukemia.

Science.gov (United States)

Trbusek, Martin; Smardova, Jana; Malcikova, Jitka; Sebejova, Ludmila; Dobes, Petr; Svitakova, Miluse; Vranova, Vladimira; Mraz, Marek; Francova, Hana Skuhrova; Doubek, Michael; Brychtova, Yvona; Kuglik, Petr; Pospisilova, Sarka; Mayer, Jiri

2011-07-01

There is a distinct connection between TP53 defects and poor prognosis in chronic lymphocytic leukemia (CLL). It remains unclear whether patients harboring TP53 mutations represent a homogenous prognostic group. We evaluated the survival of patients with CLL and p53 defects identified at our institution by p53 yeast functional assay and complementary interphase fluorescence in situ hybridization analysis detecting del(17p) from 2003 to 2010. A defect of the TP53 gene was identified in 100 of 550 patients. p53 mutations were strongly associated with the deletion of 17p and the unmutated IgVH locus (both P DBMs), structurally well-defined parts of the DNA-binding domain, manifested a clearly shorter median survival (12 months) compared with patients having missense mutations outside DBMs (41 months; P = .002) or nonmissense alterations (36 months; P = .005). The difference in survival was similar in the analysis limited to patients harboring mutation accompanied by del(17p) and was also confirmed in a subgroup harboring TP53 defect at diagnosis. The patients with p53 DBMs mutation (at diagnosis) also manifested a short median time to first therapy (TTFT; 1 month). The substantially worse survival and the short TTFT suggest a strong mutated p53 gain-of-function phenotype in patients with CLL with DBMs mutations. The impact of p53 DBMs mutations on prognosis and response to therapy should be analyzed in investigative clinical trials.

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...

The IARC TP53 mutation database: a resource for studying the significance of TP53 mutations in human cancers

Directory of Open Access Journals (Sweden)

Magali Olivier

2007-02-01

Full Text Available <p class="MsoNormal">The tumor suppressor gene TP53 is frequently inactivated by gene mutations in many types of human sporadic cancers, and inherited TP53 mutations predispose to a wide spectrum of early-onset tumors (Li-Fraumeni et Li-Fraumenilike Syndromes. All TP53 gene variations (somatic and germline mutations, as well as polymorphisms that are reported in the scientific literature or in SNP databases are compiled in the IARC TP53 Database. This database provides structured data and analysis tools to study mutation patterns in human cancers and cell-lines and to investigate the clinical impact of mutations. It contains annotations related to the clinical and pathological characteristics of tumors, as well as the demographics and carcinogen exposure of patients. The IARC TP53 web site (p53.iarc.fr/">http://www-p53.iarc.fr/ provides a search interface for the core database and includes a comprehensive user guide, a slideshow on TP53 mutations in human cancer, protocols and references for sequencing TP53 gene, and links to relevant publications and bioinformatics databases. The database interface allows download of entire data sets and propose various tools for the selection, analysis and downloads of specific sets of data according to user's query.p> <p class="MsoNormal">Recently, new annotations on the functional properties of mutant p53 proteins have been integrated in this database. Indeed, the most frequent TP53 alterations observed in cancers (75% are missense mutations that result in the production of a mutant protein that differ from the wildtype by one single amino-acid. The characterization of the biological activities of these mutant proteins is thus very important. Over the last ten years, a great amount of systematic data has been generated from experimental assays performed in

A Unique Mdm2-Binding Mode of the 3-Pyrrolin-2-one- and 2-Furanone-Based Antagonists of the p53-Mdm2 Interaction

NARCIS (Netherlands)

Surmiak, Ewa; Twarda-Clapa, Aleksandra; Zak, Krzysztof M.; Musielak, Bogdan; Tomala, Marcin D.; Kubica, Katarzyna; Grudnik, Przemyslaw; Madej, Mariusz; Jablonski, Mateusz; Potempa, Jan; Kalinowska-Tluscik, Justyna; Dömling, Alexander; Dubin, Grzegorz; Holak, Tad A.

2016-01-01

The p53 pathway is inactivated in almost all types of cancer by mutations in the p53 encoding gene or overexpression of the p53 negative regulators, Mdm2 and/or Mdmx. Restoration of the p53 function by inhibition of the p53-Mdm2/Mdmx interaction opens up a prospect for a nongenotoxic anticancer

Striatal dopamine transmission is subtly modified in human A53Tα-synuclein overexpressing mice.

Directory of Open Access Journals (Sweden)

Nicola J Platt

Full Text Available Mutations in, or elevated dosage of, SNCA, the gene for α-synuclein (α-syn, cause familial Parkinson's disease (PD. Mouse lines overexpressing the mutant human A53Tα-syn may represent a model of early PD. They display progressive motor deficits, abnormal cellular accumulation of α-syn, and deficits in dopamine-dependent corticostriatal plasticity, which, in the absence of overt nigrostriatal degeneration, suggest there are age-related deficits in striatal dopamine (DA signalling. In addition A53Tα-syn overexpression in cultured rodent neurons has been reported to inhibit transmitter release. Therefore here we have characterized for the first time DA release in the striatum of mice overexpressing human A53Tα-syn, and explored whether A53Tα-syn overexpression causes deficits in the release of DA. We used fast-scan cyclic voltammetry to detect DA release at carbon-fibre microelectrodes in acute striatal slices from two different lines of A53Tα-syn-overexpressing mice, at up to 24 months. In A53Tα-syn overexpressors, mean DA release evoked by a single stimulus pulse was not different from wild-types, in either dorsal striatum or nucleus accumbens. However the frequency responsiveness of DA release was slightly modified in A53Tα-syn overexpressors, and in particular showed slight deficiency when the confounding effects of striatal ACh acting at presynaptic nicotinic receptors (nAChRs were antagonized. The re-release of DA was unmodified after single-pulse stimuli, but after prolonged stimulation trains, A53Tα-syn overexpressors showed enhanced recovery of DA release at old age, in keeping with elevated striatal DA content. In summary, A53Tα-syn overexpression in mice causes subtle changes in the regulation of DA release in the striatum. While modest, these modifications may indicate or contribute to striatal dysfunction.

Understanding the role of p53 in adaptive response to radiation-induced germline mutations

International Nuclear Information System (INIS)

Langlois, N.L.; Quinn, J.S.; Somers, C.M.; Boreham, D.R.; Mitchel, R.E.J.

2003-01-01

Full text: Radiation-induced adaptive response is now a widely studied area of radiation biology. Studies have demonstrated reduced levels of radiation-induced biological damage when an 'adaptive dose' is given before a higher 'challenge dose' compared to when the challenge dose is given alone. It has been shown in some systems to be a result of inducible cellular repair systems. The adaptive response has been clearly demonstrated in many model systems, however its impact on heritable effects in the mammalian germline has never been studied. Expanded Simple Tandem Repeat (ESTR) loci have been used as markers demonstrating that induced heritable mutations in mice follow a dose-response relationship. Recent data in our laboratory show preliminary evidence of radiation-induced adaptive response suppressing germline mutations at ESTR loci in wild type mice. The frequency of heritable mutations was significantly reduced when a priming dose of 0.1 Gy was given 24 hours prior to a 1 Gy acute challenging dose. We are now conducting a follow-up study to attempt to understand the mechanism of this adaptive response. P53 is known to play a significant role in governing apoptosis, DNA repair and cancer induction. In order to determine what function p53 has in the adaptive response for heritable mutations, we have mated radiation treated Trp53+/- male mice (C57Bl) to untreated, normal females (C57Bl). Using DNA fingerprinting, we are investigating the rate of inherited radiation-induced mutations on pre- and post-meiotic radiation-treated gametocytes by examining mutation frequencies in offspring DNA. If p53 is integral in the mechanism of adaptive response, we should not see an adaptive response in radiation-induced heritable mutations in these mice. This research is significant in that it will provide insight to understanding the mechanism behind radiation-induced adaptive response in the mammalian germline

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)

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.

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....

TP53 p.R337H is a conditional cancer-predisposing mutation: further evidence from a homozygous patient

International Nuclear Information System (INIS)

Giacomazzi, Juliana; Hainaut, Pierre; Ashton-Prolla, Patricia; Selistre, Simone; Duarte, Juliana; Ribeiro, Jorge Pinto; Vieira, Paulo JC; Souza Macedo, Gabriel de; Rossi, Cristina; Czepielewski, Mauro; Netto, Cristina Brinkmann Oliveira

2013-01-01

Adrenocortical carcinomas (ACCs) are among the most common childhood cancers occurring in infants affected with the Li-Fraumeni and Li- Fraumeni-like (LFS/LFL) syndromes, which are caused by dominant germline mutations in the TP53 gene. In Brazil, a particular mutation, occurring in the tetramerisation domain of the gene, p.R337H, is exceedingly common due to a founder effect and is strongly associated with ACC. In this report, we describe the phenotype and long-term clinical follow-up of a female child diagnosed with ACC and homozygous for the TP53 p.R337H founder mutation. At age 11 months, the patient was diagnosed with a virilising anaplastic adrenal cortical tumour, which was completely excised without disturbing the adrenal capsule. Family history was consistent with an LFL tumour pattern, and genotyping identified the TP53 p.R337H mutation in both alleles in genomic DNA from lymphocytes and fibroblasts. Haplotype analysis confirmed the occurrence of the mutation in the same founder haplotype previously described in other Brazilian patients. No other germline or somatic TP53 mutations or rearrangements were identified. At age 9 years, the child was asymptomatic and had no evidence of endocrine derangements. Full body and brain magnetic resonance imaging (MRI) failed to detect any suspicious proliferative lesions, and cardiopulmonary exercise testing results were within the normal reference for the child’s age, ruling out a major exercise capacity deficiency. This is the first clinical and aerobic functional capacity documentation of a patient who carries two mutant TP53 alleles and no wild-type allele. Our results support the hypothesis that TP53 p.R337H, the most common TP53 mutation ever described in any population, is a conditional mutant. Furthermore, our observations over a long period of clinical follow-up suggest that TP53 p.R337H homozygotes do not have a more severe disease phenotype than do heterozygote carriers of the same mutation. Patients with

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

Simple mathematical method to quantify p53 mutations in occupational lung cancer

International Nuclear Information System (INIS)

Helal, N.L.

2005-01-01

Radon-222, a decay product of uranium-238 and a source of high linear energy transfer (LET) alpha -particles, has been implicated in the increase risk of lung cancer in uranium miners as well as non-miners. The p53 gene mutational spectrum reveals evidence for a direct causal effect of radon inhalation in lung cancer. This mutation has been proposed as a marker of radon exposure. The development of such markers may ultimately be of benefit in the reduction of occupational morbidity and mortality from occupational cancer. One of the tasks in risk assessment of genotoxic occupational radiation exposure is to devise a simple numerical method. This method may be used to quantify the relationship between radiation dose and the effect on the genetic sequences. The tumor suppressor gene (TSG) p53 is an ideal bio marker addressing questions of exposure and risk. These proteins may be suitable for the design of more effective or less invasive cancer therapies. The clinical outcome of lung cancer patients may correlate with the normal regulation of these patients and, therefore, their identification may be used as a guideline for future therapy modalities. To investigate the association between radon exposure and p53 mutations in lung tumors, we have implied a mathematical method. This method has been developed from a 2-D graphical representational technique that enables easy visualization of base distributions. This is of special relevance to libraries of single nucleotide polymorphic (SNP) genes

Clinical significance of altered nm23-H1, EGFR, RB and p53 expression in bilharzial bladder cancer

International Nuclear Information System (INIS)

Khaled, Hussein M; Bahnassy, Abeer A; Raafat, Amira A; Zekri, Abdel-Rahman N; Madboul, Maha S; Mokhtar, Nadia M

2009-01-01

Clinical characterization of bladder carcinomas is still inadequate using the standard clinico-pathological prognostic markers. We assessed the correlation between nm23-H1, Rb, EGFR and p53 in relation to the clinical outcome of patients with muscle invasive bilharzial bladder cancer (MI-BBC). nm23-H1, Rb, EGFR and p53 expression was assessed in 59 MI-BBC patients using immunohistochemistry and reverse transcription (RT-PCR) and was correlated to the standard clinico-pathological prognostic factors, patient's outcome and the overall survival (OS) rate. Overexpression of EGFR and p53 proteins was detected in 66.1% and 35.6%; respectively. Loss of nm23-H1and Rb proteins was detected in 42.4% and 57.6%; respectively. Increased EGFR and loss of nm23-H1 RNA were detected in 61.5% and 36.5%; respectively. There was a statistically significant correlation between p53 and EGFR overexpression (p < 0.0001), nm23 loss (protein and RNA), lymph node status (p < 0.0001); between the incidence of local recurrence and EGFR RNA overexpression (p= 0.003) as well as between the incidence of metastasis and altered Rb expression (p = 0.026), p53 overexpression (p < 0.0001) and mutation (p = 0.04). Advanced disease stage correlated significantly with increased EGFR (protein and RNA) (p = 0.003 & 0.01), reduced nm23-H1 RNA (p = 0.02), altered Rb (p = 0.023), and p53 overexpression (p = 0.004). OS rates correlated significantly, in univariate analysis, with p53 overexpression (p = 0.011), increased EGFR (protein and RNA, p = 0.034&0.031), nm23-H1 RNA loss (p = 0.021) and aberrations of ≥ 2 genes. However, multivariate analysis showed that only high EGFR overexpression, metastatic recurrence, high tumor grade and the combination of ≥ 2 affected markers were independent prognostic factors. nm23-H1, EGFR and p53 could be used as prognostic biomarkers in MI-BBC patients. In addition to the standard pathological prognostic factors, a combination of these markers (≥ 2) has

p53 gene mutation hotspots in skin cancer and ultraviolet induced mutation

International Nuclear Information System (INIS)

Ikehata, Hironobu

1998-01-01

Presence of certain hotspots is known in the mutation of p53 gene in skin cancer, which are codons 177, 196, 245, 248, 278 and 282 located in the exon 5-8. In these regions, mutations like C to T and CC to TT are frequent and thereby suggest that they are resulted from pyrimidine-dimers produced by ultraviolet light (UV). In cyclobutane pyrimidine dimerization (CPD), conversion of cytosine to thymine by deamination is suggested to be the primary reaction. Although studies using UVC (254 nm) suggesting that the mutation hotspots are low repair efficiency regions could not completely explain the all hotspots, those using UVB and sunlight (UVB and UVA) revealed that CPD was efficiently produced even in such regions as not explained by studies with UVC alone. Therefore, the latter studies are conceivably reasonable since the skin cancer is induced by natural sunlight. Exon 5-8 DNA is completely methylated and the absorption coefficient of 5-methylcytosine is 5-6 times as large as that of cytosine at wavelength around 290 nm. These indicate the importance of UVB in mutation of mammalian cells possessing the ability to methylate DNA. (K.H.)

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.

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

Effect of radon and its progeny on the expression and mutation of p53 in lung tissues of mice

International Nuclear Information System (INIS)

Piao Chunnan; Tian Mei; Liu Jianxiang; Ruan Jianlei; Su Xu

2010-01-01

Objective: To explore the effect of radon and its progeny on the expression and mutations of p53 in lung tissue of mouse model. Methods: Apoptosis was detected by terminal deoxynucleotidy transferase-mediated dUTP-biotin nick end labeling. The expression of p53 gene was analyzed by immunohistochemistry, Western blot and realtime-PCR. PCR-SSCP was used to detect the mutation of p53 in lung tissues. Results: Compared with those in the control group, the apoptotic index were increased significantly in 30 WLM and 60 WLM groups (t=18.11, -10.30, P<0.05). The p53 protein was increased significantly (t=-11.08, P<0.05; t=-7.00, P<0.05) in 30 WLM and 60 WLM groups. The mutation of p53 gene was not detected in lungs of radon-exposure mice. Conclusions: Lung and bronchus might be the targets of radon and its progeny, and p53 gene plays an important role in the progression of radon-induced lung injury. (authors)

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

Energy Technology Data Exchange (ETDEWEB)

Deocaris, Custer C

2000-04-01

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

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

International Nuclear Information System (INIS)

Deocaris, Custer C.

2000-04-01

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

Molecular markers for diagnostic cytology of neoplasms in the head region of the pancreas: mutation of K-ras and overexpression of the p53 protein product

NARCIS (Netherlands)

van Es, J. M.; Polak, M. M.; van den Berg, F. M.; Ramsoekh, T. B.; Craanen, M. E.; Hruban, R. H.; Offerhaus, G. J.

1995-01-01

To determine the potential efficiency of molecular markers specific for neoplastic change--mutations of the K-ras oncogene and the p53 tumour suppressor gene--in diagnosing pancreatic carcinoma. Archival cytology samples obtained from 17 patients with established pancreatic carcinoma were assayed

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.

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

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Tayebeh Hamzehloie

2012-03-01

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

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

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Zhang Xifeng

2010-09-01

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

p53 oncogene mutations in head and neck cancer based on the ...

African Journals Online (AJOL)

Yomi

2012-01-26

Jan 26, 2012 ... In order to study the p53 mutations in head and neck cancer, we explored the relationship between the different positions of the bases and the amino acids' physical and chemical properties. In this paper, the Euclidean distance (d) was defined. Furthermore, by using improved variation coefficient method,.

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

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

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Nakagawa, Yosuke [Department of Oral and Maxillofacial Surgery, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Takahashi, Akihisa [Advanced Scientific Research Leader Development Unit, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511 (Japan); Kajihara, Atsuhisa; Yamakawa, Nobuhiro; Imai, Yuichiro [Department of Oral and Maxillofacial Surgery, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Ota, Ichiro; Okamoto, Noritomo [Department of Otorhinolaryngology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Mori, Eiichiro [Department of Radiation Oncology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Noda, Taichi [Department of Dermatology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Furusawa, Yoshiya [Heavy-ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kirita, Tadaaki [Department of Oral and Maxillofacial Surgery, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan); Ohnishi, Takeo, E-mail: tohnishi@naramed-u.ac.jp [Department of Radiation Oncology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521 (Japan)

2012-07-13

Highlights: Black-Right-Pointing-Pointer High-LET radiation induces efficiently apoptosis regardless of p53 gene status. Black-Right-Pointing-Pointer We examined whether high-LET radiation depresses the Akt-survival signals. Black-Right-Pointing-Pointer High-LET radiation depresses of survival signals even in the mp53 cancer cells. Black-Right-Pointing-Pointer High-LET radiation activates Caspase-9 through depression of survival signals. Black-Right-Pointing-Pointer High-LET radiation suppresses cell growth through depression of survival signals. -- Abstract: Although mutations and deletions in the p53 tumor suppressor gene lead to resistance to low linear energy transfer (LET) radiation, high-LET radiation efficiently induces cell lethality and apoptosis regardless of the p53 gene status in cancer cells. Recently, it has been suggested that the induction of p53-independent apoptosis takes place through the activation of Caspase-9 which results in the cleavage of Caspase-3 and poly (ADP-ribose) polymerase (PARP). This study was designed to examine if high-LET radiation depresses serine/threonine protein kinase B (PKB, also known as Akt) and Akt-related proteins. Human gingival cancer cells (Ca9-22 cells) harboring a mutated p53 (mp53) gene were irradiated with 2 Gy of X-rays or Fe-ion beams. The cellular contents of Akt-related proteins participating in cell survival signaling were analyzed with Western Blotting 1, 2, 3 and 6 h after irradiation. Cell cycle distributions after irradiation were assayed with flow cytometric analysis. Akt-related protein levels decreased when cells were irradiated with high-LET radiation. High-LET radiation increased G{sub 2}/M phase arrests and suppressed the progression of the cell cycle much more efficiently when compared to low-LET radiation. These results suggest that high-LET radiation enhances apoptosis through the activation of Caspase-3 and Caspase-9, and suppresses cell growth by suppressing Akt-related signaling, even in mp

Nanotized PPARα Overexpression Targeted to Hypertrophied Myocardium Improves Cardiac Function by Attenuating the p53-GSK3β-Mediated Mitochondrial Death Pathway.

Science.gov (United States)

Rana, Santanu; Datta, Ritwik; Chaudhuri, Ratul Datta; Chatterjee, Emeli; Chawla-Sarkar, Mamta; Sarkar, Sagartirtha

2018-05-09

Metabolic remodeling of cardiac muscles during pathological hypertrophy is characterized by downregulation of fatty acid oxidation (FAO) regulator, peroxisome proliferator-activated receptor alpha (PPARα). Thereby, we hypothesized that a cardiac-specific induction of PPARα might restore the FAO-related protein expression and resultant energy deficit. In the present study, consequences of PPARα augmentation were evaluated for amelioration of chronic oxidative stress, myocyte apoptosis, and cardiac function during pathological cardiac hypertrophy. Nanotized PPARα overexpression targeted to myocardium was done by a stearic acid-modified carboxymethyl-chitosan (CMC) conjugated to a 20-mer myocyte-targeted peptide (CMCP). Overexpression of PPARα ameliorated pathological hypertrophy and improved cardiac function. Augmented PPARα in hypertrophied myocytes revealed downregulated p53 acetylation (lys 382), leading to reduced apoptosis. Such cells showed increased binding of PPARα with p53 that in turn reduced interaction of p53 with glycogen synthase kinase-3β (GSK3β), which upregulated inactive phospho-GSK3β (serine [Ser]9) expression within mitochondrial protein fraction. Altogether, the altered molecular milieu in PPARα-overexpressed hypertrophy groups restored mitochondrial structure and function both in vitro and in vivo. Cardiomyocyte-targeted overexpression of a protein of interest (PPARα) by nanotized plasmid has been described for the first time in this study. Our data provide a novel insight towards regression of pathological hypertrophy by ameliorating mitochondrial oxidative stress in targeted PPARα-overexpressed myocardium. PPARα-overexpression during pathological hypertrophy showed substantial betterment of mitochondrial structure and function, along with downregulated apoptosis. Myocardium-targeted overexpression of PPARα during pathological cardiac hypertrophy led to an overall improvement of cardiac energy deficit and subsequent cardiac

Survey of familial glioma and role of germline p16INK4A/p14ARF and p53 mutation

DEFF Research Database (Denmark)

Robertson, Lindsay B; Armstrong, Georgina N; Olver, Bianca D

2010-01-01

There is increasing recognition of familial propensity to glioma as a distinct clinical entity beyond a few rare syndromes; however its genetic basis is poorly understood. The role of p16(INK4A)/p14(ARF) and p53 mutations in sporadic glioma provides a strong rationale for investigating germline m...

A família do p53: aspectos estruturais e funcionais do p73 e do p63 The p53 family: structural and functional aspects of p73 and p63

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Alfredo Ribeiro-Silva

2003-06-01

Full Text Available O p53 é um gene regulador chave do ciclo celular que, quando sofre mutações, leva ao desenvolvimento de neoplasias, atuando, portanto, como um gene supressor tumoral em condições normais. Recentemente foram identificados genes homólogos ao p53 denominados p73 e p63, provavelmente oriundos de um gene ancestral comum. Apesar da grande homologia estrutural, os membros da família do p53 possuem diferenças funcionais entre si. O presente artigo tem por finalidade discorrer sobre os principais aspectos estruturais e funcionais do p73 e do p63, ressaltando seus papéis na tumorigênese humana. O p73 ativa vários genes responsivos ao p53 e, quando superexpresso, inibe a ação do p53. Raramente encontra-se mutado em neoplasias, e seu papel na tumorigênese humana ainda é motivo de controvérsias. O p63 não é um gene supressor tumoral clássico, sendo essencial para a manutenção de uma população de células precursoras (células-tronco em vários tecidos epiteliais. O p63 marca as células basais de vários órgãos epiteliais, como a pele e a próstata, podendo ser considerado um marcador de indiferenciação celular. O p63 é um marcador recentemente descrito e ainda requer maior investigação para determinar seu papel no desenvolvimento de neoplasias em humanos.The p53 gene has a key role in the cell cycle control. When mutated, it promotes the development of neoplasms, acting in so far as a tumor suppressor gene in normal conditions. Recently, genes homologue to p53 were identified, named p73 e p63, probably originated from a common ancestral gene. Despite the great structural homology, the members of p53 family have functional differences. This article aims to discourse about the major structural and functional aspects of p73 and p63, reinforcing their role in human tumorigenesis. P73 activates several p53 responsive genes and, when overexpressed, inhibits the p53 action. It is rarely mutated in neoplasms and its role in human

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.)

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

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Jianzhong Chen

2012-08-01

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

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

NARCIS (Netherlands)

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

1996-01-01

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

Incorporation of p-53 mutation status and Ki-67 proliferating index in ...

African Journals Online (AJOL)

Ayesha Ahmed

2018-04-26

Apr 26, 2018 ... gastric cancer. p-53 mutation status and Ki-67 proliferation index are established prognostic ... could not only be predictive in patientLs prognostics but could also form a basis of molecular ... a similar status to Her2-neu in gastric cancer, yet no ..... HER2-based biology in 1,006 cases of gastric cancer in.

Mir-34a mimics are potential therapeutic agents for p53-mutated and chemo-resistant brain tumour cells.

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Yuen Ngan Fan

Full Text Available Chemotherapeutic drug resistance and relapse remains a major challenge for paediatric (medulloblastoma and adult (glioblastoma brain tumour treatment. Medulloblastoma tumours and cell lines with mutations in the p53 signalling pathway have been shown to be specifically insensitive to DNA damaging agents. The aim of this study was to investigate the potential of triggering cell death in p53 mutated medulloblastoma cells by a direct activation of pro-death signalling downstream of p53 activation. Since non-coding microRNAs (miRNAs have the ability to fine tune the expression of a variety of target genes, orchestrating multiple downstream effects, we hypothesised that triggering the expression of a p53 target miRNA could induce cell death in chemo-resistant cells. Treatment with etoposide, increased miR-34a levels in a p53-dependent fashion and the level of miR-34a transcription was correlated with the cell sensitivity to etoposide. miR-34a activity was validated by measuring the expression levels of one of its well described target: the NADH dependent sirtuin1 (SIRT1. Whilst drugs directly targeting SIRT1, were potent to trigger cell death at high concentrations only, introduction of synthetic miR-34a mimics was able to induce cell death in p53 mutated medulloblastoma and glioblastoma cell lines. Our results show that the need of a functional p53 signaling pathway can be bypassed by direct activation of miR-34a in brain tumour cells.

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.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-11-15

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

P53, K-RAS, β-CATENIN, C-KIT and BAK mutations in the lung cancer of Chinese and Japanese patients

International Nuclear Information System (INIS)

Shuo Xing; Nobotoshi Nawa; Kazuhiro Tanabe; Tadashi Hongyo; Li- Ya Li; Jing-Tian Tang; Mitsunori Ohta

2005-01-01

Seventeen Chinese (Beijing) and 24 Japanese (Osaka) lung cancer cases were analyzed for mutations of p53, K-ras, β-catenin, c-kit and bak genes by PCR-SSCP analysis followed by direct sequencing. Significantly higher mutation frequency of p53 gene, one of key genes for radiation sensitivity, was found in Chinese cases (11/17; 64.7 %) than Japanese cases (8/24; 33.3 %) (p< O.O5). Fourteen of the 16 mutations found in the Chinese cases were transitions at exon 4,5 and intron 4. In the Japanese cases, of the total of 11 mutations, 5 were transitions and 5 were transversions and one was deletion. Six β-catenin mutations were found in 6 Chinese cases (35.3 % ) at codon 53 and 58, and 4 were found in 3 Japanese cases (12.5 %). C-kit mutations were detected in 5 Chinese cases (29.4 %), while no mutations were found in Japanese cases (p< O.O5). No K-ras mutation was found in both Chinese and Japanese cases. For the first time, we report on bak mutation in human lung cancer in Chinese (2/17; 11.8% ) and Japanese cases (2/24; 8.3% ). C-kit and bak genes are also definitive factors to radiosensitivity. These data thus suggest that there were apparent differences in frequency and/or mutational types of p53, β-catenin and c-kit? genes between Chinese and Japanese cases. The differences can be attributed to factors such as lifestyles including smoking and racial and/or environmental factors, and also to the prediction of the response to radiotherapy. (author)

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

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

The expression of p53 protein in patients with multiple myeloma

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Marković Olivera

2007-01-01

Full Text Available Introduction: Although mutations of p53 are one of the most often acquired genetic changes in malignant tumors, these mutations are rare events in patients with newly diagnosed multiple myeloma (MM. Moreover, there are a few literature data about clinical significance of p53 overexpression in multiple myeloma. Objective The aim of our study was to evaluate the clinical significance of p53 immunoexpression in multiple myeloma. Method A total of 58 patients with newly diagnosed MM (26 females and 32 males, mean age 62 years were enrolled in the study. The diagnosis of MM was made according to criteria of Chronic Leukemia-Myeloma Task Force. Clinical staging was done according to Durie and Salmon classification (4 patients had disease stage I, 15 patients stage II and 39 patients stage III. The histological grade and histological stage were determined according to predominant plasma cell morphology and volume of myeloma infiltration, respectively. Standard immunohistochemical analysis with p53 antibody in B5-fixed and paraffin- embedded bone marrow specimens was used to evaluate the expression of p53 in myeloma cells. The specimens were considered positive when ≥5% of plasma cells exhibited clear nuclear positivity. Results Out of 58 patients, p53 expression was detected in 9 (15.52%. No significant correlation was found between p53 expression and clinical stage (I+II vs. III, Я2-microglobulin level (≤6 mg/L vs. >6mg/L, histological grade (I vs. II+III, histological stage (<20% vs. 21-50% vs. >50% and the extent of osteolytic lesions (≤3 vs. >3 lesions. Median survival of patients with p53 immunoreactivity in =>5% of plasma cells was 10 months, whilst median survival of patients with p53 immunoreactivity in <5% of plasma cells was 36 months. However, such difference was not significant (p=0.2. Conclusion The frequency of p53 immunoexpression in our group of newly diagnosed MM was relatively low. Although p53 immunoexpression was not

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).

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

International Nuclear Information System (INIS)

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

2005-01-01

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

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

Science.gov (United States)

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

2015-09-01

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

Overexpressed ubiquitin ligase Cullin7 in breast cancer promotes cell proliferation and invasion via down-regulating p53

International Nuclear Information System (INIS)

Guo, Hongsheng; Wu, Fenping; Wang, Yan; Yan, Chong; Su, Wenmei

2014-01-01

Highlights: • Cullin7 is overexpressed in human breast cancer samples. • Cullin7 stimulated proliferation and invasion of breast cancer cells. • Inhibition of p53 contributes to Cullin7-induced proliferation and invasion. - Abstract: Ubiquitin ligase Cullin7 has been identified as an oncogene in some malignant diseases such as choriocarcinoma and neuroblastoma. However, the role of Cullin7 in breast cancer carcinogenesis remains unclear. In this study, we compared Cullin7 protein levels in breast cancer tissues with normal breast tissues and identified significantly higher expression of Cullin7 protein in breast cancer specimens. By overexpressing Cullin7 in breast cancer cells HCC1937, we found that Cullin7 could promote cell growth and invasion in vitro. In contrast, the cell growth and invasion was inhibited by silencing Cullin7 in breast cancer cell BT474. Moreover, we demonstrated that Cullin7 promoted breast cancer cell proliferation and invasion via down-regulating p53 expression. Thus, our study provided evidence that Cullin7 functions as a novel oncogene in breast cancer and may be a potential therapeutic target for breast cancer management

Overexpressed ubiquitin ligase Cullin7 in breast cancer promotes cell proliferation and invasion via down-regulating p53

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Guo, Hongsheng [Department of Histology and Embryology, Guangdong Medical College, Dongguan 523808, Guangdong (China); Wu, Fenping [The 7th People’s Hospital of Chengdu, Chengdu 610041, Sichuan (China); Wang, Yan [The Second School of Clinical Medicine, Guangdong Medical College, Dongguan 523808, Guangdong (China); Yan, Chong [School of Pharmacy, Guangdong Medical College, Dongguan 523808, Guangdong (China); Su, Wenmei, E-mail: wenmeisutg@126.com [Oncology of Affiliated Hospital Guangdong Medical College, Zhanjiang 524000, Guangdong (China)

2014-08-08

Highlights: • Cullin7 is overexpressed in human breast cancer samples. • Cullin7 stimulated proliferation and invasion of breast cancer cells. • Inhibition of p53 contributes to Cullin7-induced proliferation and invasion. - Abstract: Ubiquitin ligase Cullin7 has been identified as an oncogene in some malignant diseases such as choriocarcinoma and neuroblastoma. However, the role of Cullin7 in breast cancer carcinogenesis remains unclear. In this study, we compared Cullin7 protein levels in breast cancer tissues with normal breast tissues and identified significantly higher expression of Cullin7 protein in breast cancer specimens. By overexpressing Cullin7 in breast cancer cells HCC1937, we found that Cullin7 could promote cell growth and invasion in vitro. In contrast, the cell growth and invasion was inhibited by silencing Cullin7 in breast cancer cell BT474. Moreover, we demonstrated that Cullin7 promoted breast cancer cell proliferation and invasion via down-regulating p53 expression. Thus, our study provided evidence that Cullin7 functions as a novel oncogene in breast cancer and may be a potential therapeutic target for breast cancer management.

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

Science.gov (United States)

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

2009-01-01

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

TP53 mutations in clinically normal mucosa adjacent to oral carcinomas

DEFF Research Database (Denmark)

Thode, Christenze; Bilde, Anders; von Buchwald, Christian

2010-01-01

BACKGROUND: The tumour-suppressor protein p53 often accumulates in histologically normal epithelium adjacent to oral squamous cell carcinomas (OSCC). We investigated whether this was associated with mutations in TP53, the gene for p53, and might implicate impending malignancy. METHODS: Specimens...... products were separated by denatured gradient gel electrophoresis. Fragments with a deviant DGEE pattern were sequenced. RESULTS: TP53 mutations were found in six of 18 tumours. Fourteen specimens contained histologically normal mucosa adjacent to the tumour; 13 of these showed small clusters of p53...

Targeting the p53 Pathway in Ewing Sarcoma

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

2011-01-01

The p53 tumour suppressor plays a pivotal role in the prevention of oncogenic transformation. Cancers frequently evade the potent antitumour surveillance mechanisms of p53 through mutation of the TP53 gene, with approximately 50% of all human malignancies expressing dysfunctional, mutated p53 proteins. Interestingly, genetic lesions in the TP53 gene are only observed in 10% of Ewing Sarcomas, with the majority of these sarcomas expressing a functional wild-type p53. In addition, the p53 downstream signaling pathways and DNA-damage cell cycle checkpoints remain functionally intact in these sarcomas. This paper summarizes recent insights into the functional capabilities and regulation of p53 in Ewing Sarcoma, with a particular focus on the cross-talk between p53 and the EWS-FLI1 gene rearrangement frequently associated with this disease. The development of several activators of p53 is discussed, with recent evidence demonstrating the potential of small molecule p53 activators as a promising systemic therapeutic approach for the treatment of Ewing Sarcomas with wild-type p53. PMID:21197471

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

International Nuclear Information System (INIS)

Ito, Atsushi; Nakano, Hisako; Shinohara, Kunio

2010-01-01

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

Involvement of p53 Mutation and Mismatch Repair Proteins Dysregulation in NNK-Induced Malignant Transformation of Human Bronchial Epithelial Cells

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Ying Shen

2014-01-01

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

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.

Drug resistance to inhibitors of the human double minute-2 E3 ligase is mediated by point mutations of p53, but can be overcome with the p53 targeting agent RITA.

Science.gov (United States)

Jones, Richard J; Bjorklund, Chad C; Baladandayuthapani, Veerabhadran; Kuhn, Deborah J; Orlowski, Robert Z

2012-10-01

The human double minute (HDM)-2 E3 ubiquitin ligase plays a key role in p53 turnover and has been validated preclinically as a target in multiple myeloma (MM) and mantle cell lymphoma (MCL). HDM-2 inhibitors are entering clinical trials, and we therefore sought to understand potential mechanisms of resistance in lymphoid models. Wild-type p53 H929 MM and Granta-519 MCL cells resistant to MI-63 or Nutlin were generated by exposing them to increasing drug concentrations. MI-63-resistant H929 and Granta-519 cells were resistant to Nutlin, whereas Nutlin-resistant cells displayed cross-resistance to MI-63. These cells also showed cross-resistance to bortezomib, doxorubicin, cisplatin, and melphalan, but remained sensitive to the small molecule inhibitor RITA (reactivation of p53 and induction of tumor cell apoptosis). HDM-2 inhibitor-resistant cells harbored increased p53 levels, but neither genotoxic nor nongenotoxic approaches to activate p53 induced HDM-2 or p21. Resequencing revealed wild-type HDM-2, but mutations were found in the p53 DNA binding and dimerization domains. In resistant cells, RITA induced a G(2)-M arrest, upregulation of p53 targets HDM-2, PUMA, and NOXA, and PARP cleavage. Combination regimens with RITA and MI-63 resulted in enhanced cell death compared with RITA alone. These findings support the possibility that p53 mutation could be a primary mechanism of acquired resistance to HDM-2 inhibitors in MCL and MM. Furthermore, they suggest that simultaneous restoration of p53 function and HDM-2 inhibition is a rational strategy for clinical translation.

DETECTION OF K-RAS AND P53 MUTATIONS IN SPUTUM SAMPLES OF LUNG CANCER PATIENTS USING LASER CAPTURE MICRODISSECTION MICROSCOPE AND MUTATION ANALYSIS

Science.gov (United States)

Detection of K-ras and p53 Mutations in Sputum Samples of Lung Cancer Patients Using Laser Capture Microdissection Microscope and Mutation AnalysisPhouthone Keohavong a,*, Wei-Min Gao a, Kui-Cheng Zheng a, Hussam Mady b, Qing Lan c, Mona Melhem b, and Judy Mumford d.<...

The different faces of the p. A53T alpha-synuclein mutation: A screening of Greek patients with parkinsonism and/or dementia.

Science.gov (United States)

Breza, Marianthi; Koutsis, Georgios; Karadima, Georgia; Potagas, Constantin; Kartanou, Chrisoula; Papageorgiou, Sokratis G; Paraskevas, George P; Kapaki, Elisabeth; Stefanis, Leonidas; Panas, Marios

2018-04-13

The p. A53T mutation in the alpha-synuclein (SNCA) gene is a rare cause of autosomal dominant Parkinson's disease (PD). Although generally rare, it is particularly common in the Greek population due to a founder effect. A53T-positive PD patients often develop dementia during disease course and may very rarely present with dementia. We screened for the p. A53T SNCA mutation a total of 347 cases of Greek origin with parkinsonism and/or dementia, collected over 15 years at the Neurogenetics Unit, Eginition Hospital, University of Athens. Cases were classified into: "pure parkinsonism", "pure dementia" and "parkinsonism plus dementia". In total, 4 p. A53T SNCA mutation carriers were identified. All had autosomal dominant family history and early onset. Screening of the "pure parkinsonism" category revealed 2 cases with typical PD. The other two mutation carriers were identified in the "parkinsonism plus dementia" category. One had a diagnosis of PD dementia and the other of behavioral variant frontotemporal dementia. Screening of patients with "pure dementia" failed to identify any further A53T-positive cases. Our results confirm that the p. A53T SNCA mutation is relatively common in Greek patients with PD or PD plus dementia, particularly in cases with early onset and/or autosomal dominant family history. Copyright © 2017 Elsevier B.V. All rights reserved.

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,

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.

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

Science.gov (United States)

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

2009-01-01

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

High LET radiation enhances apoptosis in mutated p53 cancer cells through Caspase-9 activation

International Nuclear Information System (INIS)

Yamakawa, Nobuhiro; Takahashi, Akihisa; Mori, Eiichiro; Imai, Yuichiro; Ohnishi, Ken; Kirita, Tadaaki; Ohnishi, Takeo; Furusawa, Yoshiya

2008-01-01

Although mutations in the p53 gene can lead to resistance to radiotherapy, chemotherapy and thermotherapy, high linear energy transfer (LET) radiation induces apoptosis regardless of p53 gene status in cancer cells. The aim of this study was to clarify the mechanisms involved in high LET radiation-induced apoptosis. Human gingival cancer cells (Ca9-22 cells) containing a mutated p53 (mp53) gene were irradiated with X-rays, C-ion (13-100 KeV/μm), or Fe-ion beams (200 KeV/μm). Cellular sensitivities were determined using colony forming assays. Apoptosis was detected and quantified with Hoechst 33342 staining. The activity of Caspase-3 was analyzed with Western blotting and flow cytometry. Cells irradiated with high LET radiation showed a high sensitivity with a high frequency of apoptosis induction. The relative biological effectiveness (RBE) values for the surviving fraction and apoptosis induction increased in a LET-dependent manner. Both RBE curves reached a peak at 100 KeV/μm, and then decreased at values over 100 KeV/μm. When cells were irradiated with high LET radiation, Caspase-3 was cleaved and activated, leading to poly (ADP-ribose) polymerase (PARP) cleavage. In addition, Caspase-9 inhibitor suppressed Caspase-3 activation and apoptosis induction resulting from high LET radiation to a greater extent than Caspase-8 inhibitor. These results suggest that high LET radiation enhances apoptosis by activation of Caspase-3 through Caspase-9, even in the presence of mp53. (author)

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)

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

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Francisco Navarro

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

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

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

International Nuclear Information System (INIS)

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

2003-01-01

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

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.

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.

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.

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.

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.

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

Evidence that expression of a mutated p53 gene attenuates apoptotic cell death in human gastric intestinal-type carcinomas in vivo.

Science.gov (United States)

Ishida, M; Gomyo, Y; Ohfuji, S; Ikeda, M; Kawasaki, H; Ito, H

1997-05-01

To examine in vivo the validity of the results of experiments in vitro, we analyzed the relationship between p53 gene status and apoptotic cell death of human gastric intestinal-type adenocarcinomas. Surgical specimens were classified into two categories: 18 gastric cancers with nuclear p53 protein (A), and 17 gastric cancers without nuclear p53 protein (B). Polymerase chain reaction-single strand conformation polymorphism disclosed a shifted band that corresponded to a mutation in the p53 gene in 13 cases (72%) in category A and 3 cases (18%) in category B, the frequency being significantly higher in the former (P terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The TUNEL index [TI; (the number of TUNEL-positive apoptotic cells/the total number of tumor cells) x 100] was 3.8 +/- 1.4% in category A and 4.9 +/- 1.2% in category B, the value being significantly lower in the former (P gastric cancer, in accordance with the previous in vitro finding that p53 gene mutation provides a possible selective advantage for tumor cell proliferation, and (2) apoptosis is related not only to expression of p53 and the stage of the cell cycle, but also to p53-independent and cell cycle-independent events.

Adaptation of cancer cells from different entities to the MDM2 inhibitor nutlin-3 results in the emergence of p53-mutated multi-drug-resistant cancer cells

NARCIS (Netherlands)

Michaelis, M.; Rothweiler, F.; Barth, S.; Cinatl, J.; van Rikxoort, M.; Loeschmann, N.; Voges, Y.; Breitling, R.; von Deimling, A.; Roedel, F.; Weber, K.; Fehse, B.; Mack, E.; Stiewe, T.; Doerr, H. W.; Speidel, D.; Cinatl, J.; Cinatl jr., J.; Stephanou, A.

2011-01-01

Six p53 wild-type cancer cell lines from infrequently p53-mutated entities (neuroblastoma, rhabdomyosarcoma, and melanoma) were continuously exposed to increasing concentrations of the murine double minute 2 inhibitor nutlin-3, resulting in the emergence of nutlin-3-resistant, p53-mutated sublines

Molecular analysis of p53 and K-ras in lung carcinomas of coal miners

Energy Technology Data Exchange (ETDEWEB)

Sarkar, F.H.; Li, Y.W.; Vallyathan, V. [Wayne State University, Detroit, MI (United States). School of Medicine, Dept. of Pathology

2001-10-01

Thirty-three cases of non-small cell lung cancers (NSCLC) from the archives of National Coal Workers' Autopsy Study were studied for mutational alterations in p53 and K-ras using PCR-SSCP, DNA sequencing and PCR-oligonucleotide probe hybridization techniques. Mutations of the p53 were observed in 4 smokers (19%) and one in a never smoker (8%). Two polymorphisms in smokers were detected at codon 213, a common site for sequence variation. Among the smokers the p53 mutations were in the heavy smokers. In never smokers there was only a single p53 mutation and two K-ras mutations. In never smokers the frequency of K-ras mutations was similar (17%) in smokers, but one never smoker had two K-ras mutations. Mutations of p53 were more frequent in adenocarcinomas (27%) and they were AT-GC transitions. There were two large cell undifferentiated carcinomas with p53 mutation and one with a K-ras mutation. Two of the 16 squamous cell carcinomas were positive for p53 mutation, while no K-ras mutations were found in this group. The results of these preliminary studies indicate a moderately different mutational spectrum of p53 and K-ras in coal miners independent of cigarette smoking. The mutational spectrum observed in this study of coal miners with heavy cigarette smoking history suggest a protective effect of coal mine dust in preventing abnormal mutations induced by chemical carcinogens in cigarette smoke or reactive oxygen species.

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

International Nuclear Information System (INIS)

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

2005-01-01

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

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.

Plasmid pKM101-dependent repair and mutagenesis in Escherichia coli cells with mutations lexB30 tif and zab-53 in the recA gene

International Nuclear Information System (INIS)

Blanco, M.; Rebollo, J.E.

1981-01-01

Bacterial survival after UV irradiation was increased in E. coli K12 lex B30 and tif zab-53 mutants harboring plasmid pKM101. Mutagenesis in response to UV was observed in these bacteria which, in absence of pKM101, are not UV-mutable. The mutator effect observed in unirradiated wild-type cells containing pKM101 was higher after incubation at 30 0 C with adenine than at 37 0 C. This effect was still enhanced by tif mutation, even in the tif zab-53 strain, but it was abolished by lexB30 mutation. In the tif zab-53 (pKM101) strain, repair and mutagenesis of UV-irradiated phage lambda was observed, but not in the lexB30 mutant carrying pKM101. The pKM101 mutant, pGW1, was unable to protect tif zab-53 bacteria against killing by UV, whereas the protection of lexB30 was intermediate; moreover, it did not promote the mutator effect at 30 0 C or enhance phage repair and mutagenesis in tif zab-53 cells. All UV-induced bacterial mutations in lexB30 (pKM101) strain were suppressors; in contrast, true revertants were found after UV irradiation of the tif zab-53 (pKM101) cells. (orig./AJ)

Immunohistochemical study of p53 overexpression in radiation-induced colon cancers

International Nuclear Information System (INIS)

Minami, Kazunori; Hayashi, Nobuyuki; Mokarim, A.; Matsuzaki, Sumihiro; Ito, Masahiro; Sekine, Ichiro.

1998-01-01

The expressions of p53 and proliferating cell nuclear antigen (PCNA) were studied immunohistochemically from paraffin sections of 7 cases (9 lesions) of radiation-induced colon cancer and 42 cases of spontaneous colon cancer. Age distribution of radiation-induced and spontaneous colon cancer were 68.1 years (range, 56 to 77 years) and 67.4 years (range, 31 to 85 years), respectively. Among the radiation-induced colon cancers, there were 3 lesions of mucinous carcinoma (33%), a much higher than found for spontaneous mucinous cancer. Immunohistochemically, p53 protein expression was detected in 7/9 (78%) of radiation-induced cancers and in 23/42 (55%) of spontaneous colon cancers. χ 2 analysis found no significant differences between radiation-induced and spontaneous colon cancers in age distribution or p53-positive staining for frequency, histopathology, or Dukes'' classification. In radiation colitis around the cancers including aberrant crypts, spotted p53 staining and abnormal and scattered PCNA-positive staining were observed. In histologically normal cells, p53 staining was almost absent and PCNA-positive staining was regularly observed in the lower half of the crypt. In radiation colitis including aberrant glands, cellular proliferation increased and spotted p53 expression was observed. This study suggests that radiation colitis and aberrant glands might possess malignant potential and deeply associate with carcinogenesis of radiation-induced colon cancer. (author)

A point mutation of human p53, which was not detected as a mutation by a yeast functional assay, led to apoptosis but not p21Waf1/Cip1/Sdi1 expression in response to ionizing radiation in a human osteosarcoma cell line, Saos-2

International Nuclear Information System (INIS)

Okaichi, Kumio; Wang Lihong; Sasaki, Ji-ichiro; Saya, Hideyuki; Tada, Mitsuhiro; Okumura, Yutaka

1999-01-01

Purpose: The 123A point mutation of p53 showed increased radiosensitivity, whereas other mutations (143A, 175H, and 273H) were not affected. To determine the reason for increased radiosensitivity of the 123A mutation, the response of the transformant of 123A mutation to ionizing radiation (IR) was examined and compared to those of transformants with the wild type p53 or other point mutations (143A, 175H, and 273H). Methods and Materials: Stable transformants with a mutant or wild type p53 made by introducing cDNA into the human osteosarcoma cell line, Saos-2, which lacks an endogenous p53 were used. The transcriptional activity of mutant p53 was examined using a yeast functional assay. The transformants were examined for the accumulation of p53, the induction of p21 Waf1/Cip1/Sdi1 (hereafter referred to as p21), and the other response of p53-responsive genes (MDM2, Bax, and Bcl-2) by Western blotting. Apoptosis was analyzed by detection of DNA fragmentation. Results: The 123A point mutation of p53 was detected as a wild type in the yeast functional assay. The 123A mutant accumulated p53 in response to IR. The 123A mutant did not induce p21, but normally responded to MDM2, Bax, and Bcl-2. The 123A mutant entered apoptosis earlier than the wild type p53 transformant, and induced Fas at earlier in response to IR. Conclusion: The 123A mutant led to apoptosis, but not p21 expression in response to IR. The occurrence of apoptosis, but not induction of p21, corresponded to the radiosensitivity in the transformant. The early occurrence of apoptosis in 123A transformants may depend on the early induction of Fas

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.

WNT activation by lithium abrogates TP53 mutation associated radiation resistance in medulloblastoma.

Science.gov (United States)

Zhukova, Nataliya; Ramaswamy, Vijay; Remke, Marc; Martin, Dianna C; Castelo-Branco, Pedro; Zhang, Cindy H; Fraser, Michael; Tse, Ken; Poon, Raymond; Shih, David J H; Baskin, Berivan; Ray, Peter N; Bouffet, Eric; Dirks, Peter; von Bueren, Andre O; Pfaff, Elke; Korshunov, Andrey; Jones, David T W; Northcott, Paul A; Kool, Marcel; Pugh, Trevor J; Pomeroy, Scott L; Cho, Yoon-Jae; Pietsch, Torsten; Gessi, Marco; Rutkowski, Stefan; Bognár, Laszlo; Cho, Byung-Kyu; Eberhart, Charles G; Conter, Cecile Faure; Fouladi, Maryam; French, Pim J; Grajkowska, Wieslawa A; Gupta, Nalin; Hauser, Peter; Jabado, Nada; Vasiljevic, Alexandre; Jung, Shin; Kim, Seung-Ki; Klekner, Almos; Kumabe, Toshihiro; Lach, Boleslaw; Leonard, Jeffrey R; Liau, Linda M; Massimi, Luca; Pollack, Ian F; Ra, Young Shin; Rubin, Joshua B; Van Meir, Erwin G; Wang, Kyu-Chang; Weiss, William A; Zitterbart, Karel; Bristow, Robert G; Alman, Benjamin; Hawkins, Cynthia E; Malkin, David; Clifford, Steven C; Pfister, Stefan M; Taylor, Michael D; Tabori, Uri

2014-12-24

TP53 mutations confer subgroup specific poor survival for children with medulloblastoma. We hypothesized that WNT activation which is associated with improved survival for such children abrogates TP53 related radioresistance and can be used to sensitize TP53 mutant tumors for radiation. We examined the subgroup-specific role of TP53 mutations in a cohort of 314 patients treated with radiation. TP53 wild-type or mutant human medulloblastoma cell-lines and normal neural stem cells were used to test radioresistance of TP53 mutations and the radiosensitizing effect of WNT activation on tumors and the developing brain. Children with WNT/TP53 mutant medulloblastoma had higher 5-year survival than those with SHH/TP53 mutant tumours (100% and 36.6%±8.7%, respectively (p<0.001)). Introduction of TP53 mutation into medulloblastoma cells induced radioresistance (survival fractions at 2Gy (SF2) of 89%±2% vs. 57.4%±1.8% (p<0.01)). In contrast, β-catenin mutation sensitized TP53 mutant cells to radiation (p<0.05). Lithium, an activator of the WNT pathway, sensitized TP53 mutant medulloblastoma to radiation (SF2 of 43.5%±1.5% in lithium treated cells vs. 56.6±3% (p<0.01)) accompanied by increased number of γH2AX foci. Normal neural stem cells were protected from lithium induced radiation damage (SF2 of 33%±8% for lithium treated cells vs. 27%±3% for untreated controls (p=0.05). Poor survival of patients with TP53 mutant medulloblastoma may be related to radiation resistance. Since constitutive activation of the WNT pathway by lithium sensitizes TP53 mutant medulloblastoma cells and protect normal neural stem cells from radiation, this oral drug may represent an attractive novel therapy for high-risk medulloblastomas.

Vaccination with p53-peptide-pulsed dendritic cells, of patients with advanced breast cancer: report from a phase I study

DEFF Research Database (Denmark)

Svane, Inge Marie; Pedersen, Anders E; Johnsen, Hans E

2004-01-01

the treatment. In conclusion, the strategy for p53-DC vaccination seems safe and without toxicity. Furthermore, indications of both immunologic and clinical effect were found in heavily pretreated patients with advanced breast cancer. An independent clinical effect of repeated administration of DCs and IL-2 can......Peptides derived from over-expressed p53 protein are presented by class I MHC molecules and may act as tumour-associated epitopes. Due to the diversity of p53 mutations, immunogenic peptides representing wild-type sequences are preferable as a basis for a broad-spectrum p53-targeting cancer vaccine......) loaded with a cocktail of three wild-type and three modified p53 peptides are being analysed in six HLA-A2+ patients with progressive advanced breast cancer. Vaccinations were well tolerated and no toxicity was observed. Disease stabilisation was seen in two of six patients, one patient had a transient...

Characterization of cancer-associated missense mutations in MDM2

OpenAIRE

Chauhan, Krishna M.; Ramakrishnan, Gopalakrishnan; Kollareddy, Madhusudhan; Martinez, Luis A.

2015-01-01

MDM2 is an E3 ubiquitin ligase that binds the N-terminus of p53 and promotes its ubiquitin-dependent degradation. Elevated levels of MDM2 due to overexpression or gene amplification can contribute to tumor development by suppressing p53 activity. Since MDM2 is an oncogene, we explored the possibility that other genetic lesions, namely missense mutations, might alter its activities. We selected mutations in MDM2 that reside in one of the 4 key regions of the protein: p53 binding domain, acidic...

Characterization of mutations and loss of heterozygosity of p53 and K-ras2 in pancreatic cancer cell lines by immobilized polymerase chain reaction

Directory of Open Access Journals (Sweden)

Edwards Jeremy

2003-07-01

Full Text Available Abstract Background The identification of known mutations in a cell population is important for clinical applications and basic cancer research. In this work an immobilized form of the polymerase chain reaction, referred to as polony technology, was used to detect mutations as well as gene deletions, resulting in loss of heterozygosity (LOH, in cancer cell lines. Specifically, the mutational hotspots in p53, namely codons 175, 245, 248, 249, 273, and 282, and K-ras2, codons 12, 13 and 61, were genotyped in the pancreatic cell line, Panc-1. In addition LOH analysis was also performed for these same two genes in Panc-1 by quantifying the relative gene copy number of p53 and K-ras2. Results Using polony technology, Panc-1 was determined to possess only one copy of p53, which possessed a mutation in codon 273, and two copies of K-ras2, one wildtype and one with a mutation in codon 12. To further demonstrate the general approach of this method, polonies were also used to detect K-ras2 mutations in the pancreatic cell lines, AsPc-1 and CAPAN-1. Conclusions In conclusion, we have developed an assay that can detect mutations in hotspots of p53 and K-ras2 as well as diagnose LOH in these same genes.

Sirt1 overexpression suppresses fluoride-induced p53 acetylation to alleviate fluoride toxicity in ameloblasts responsible for enamel formation.

Science.gov (United States)

Suzuki, Maiko; Ikeda, Atsushi; Bartlett, John D

2018-03-01

Low-dose fluoride is an effective caries prophylactic, but high-dose fluoride is an environmental health hazard that causes skeletal and dental fluorosis. Treatments to prevent fluorosis and the molecular pathways responsive to fluoride exposure remain to be elucidated. Previously we showed that fluoride activates SIRT1 as an adaptive response to protect cells. Here, we demonstrate that fluoride induced p53 acetylation (Ac-p53) [Lys379], which is a SIRT1 deacetylation target, in ameloblast-derived LS8 cells in vitro and in enamel organ in vivo. Here we assessed SIRT1 function on fluoride-induced Ac-p53 formation using CRISPR/Cas9-mediated Sirt1 knockout (LS8 Sirt/KO ) cells or CRISPR/dCas9/SAM-mediated Sirt1 overexpressing (LS8 Sirt1/over ) cells. NaF (5 mM) induced Ac-p53 formation and increased cell cycle arrest via Cdkn1a/p21 expression in Wild-type (WT) cells. However, fluoride-induced Ac-p53 was suppressed by the SIRT1 activator resveratrol (50 µM). Without fluoride, Ac-p53 persisted in LS8 Sirt/KO cells, whereas it decreased in LS8 Sirt1/over . Fluoride-induced Ac-p53 formation was also suppressed in LS8 Sirt1/over cells. Compared to WT cells, fluoride-induced Cdkn1a/p21 expression was elevated in LS8 Sirt/KO and these cells were more susceptible to fluoride-induced growth inhibition. In contrast, LS8 Sirt1/over cells were significantly more resistant. In addition, fluoride-induced cytochrome-c release and caspase-3 activation were suppressed in LS8 Sirt1/over cells. Fluoride induced expression of the DNA double strand break marker γH2AX in WT cells and this was augmented in LS8 Sirt1/KO cells, but was attenuated in LS8 Sirt1/over cells. Our results suggest that SIRT1 deacetylates Ac-p53 to mitigate fluoride-induced cell growth inhibition, mitochondrial damage, DNA damage and apoptosis. This is the first report implicating Ac-p53 in fluoride toxicity.

E2F-1-Induced p53-independent apoptosis in transgenic mice

DEFF Research Database (Denmark)

Holmberg, Christian Henrik; Helin, K.; Sehested, M.

1998-01-01

The E2F transcription factors are key targets for the retinoblastoma protein, pRB. By inactivation of E2Fs, pRB prevents progression to the S phase. To test proliferative functions of E2F, we generated transgenic mice expressing human E2F-1 and/or human DP-1. When the hydroxymethyl glutaryl...... involving increased apoptosis in the germinal epithelium. This effect was potentiated by simultaneous overexpression of DP-1. Testicular atrophy as a result of overexpression of E2F-1 and DP-1 is independent of functional p53, since p53-nullizygous transgenic mice overexpressing E2F-1 and DP-1 also suffered...

Absence of p53 gene mutations in mice colon pre-cancerous stage induced by o-nitrotoluene

Directory of Open Access Journals (Sweden)

Nahed A Hussien

2014-01-01

Conclusion: The results from the present study indicate that point mutations in the p53 gene, in the coding region (exons 5-8 and outside it (exons 10, 11, are not involved in the development of the colon precancerous stage induced by o-nt in mice.

Environmental Exposures, Genetic Polymorphisms and p53 Mutational Spectra in a Case-Control Study of Breast Cancer

National Research Council Canada - National Science Library

Shields, eter

1999-01-01

.... Other genetic analyses are completed for MEH3, MEH4, CYP2D6, GSTMl, GST-T and CYP1A1. We have been validating a p53 mutational spectra detection technology using the Affymetrix gene chip array...

p53-Dependent radiation-induced apoptosis in vivo: relationship to Bcl-2 and Bax expression

International Nuclear Information System (INIS)

Hasegawa, Masatoshi; Suzuki, Yoshiyuki; Furuta, Masaya; Yamakawa, Michitaka; Maebayashi, Katsuya; Hayakawa, Kayoko; Saito, Yoshihiro; Mitsuhashi, Norio; Niibe, Hideo

1997-01-01

, but negative for p21 and Bax. They did not show significant differences between before and after irradiation. These three tumors often showed very weak staining for Bax, and it was much weaker than in the positive control slides. PCR-SSCP analysis showed a mutation in exon 7 of the p53 gene in the glioblastoma and the small cell lung cancer, but, no mutations were demonstrated in exons of the p53 gene in the ependymoblastoma. Conclusion: The radiation-induced apoptosis in the ependymoblastoma was highly correlated with p53 protein expression, but, the changes in Bcl-2 and Bax expression did not always correspond to the frequency of apoptosis. In the other two tumors, radiation induced apoptosis in only a few cells. These tumors showed overexpression of p53 and Bcl-2, and a mutation of p53 gene was also suggested by PCR-SSCP analysis

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

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.

High resolution melting for mutation scanning of TP53 exons 5–8

International Nuclear Information System (INIS)

Krypuy, Michael; Dobrovic, Alexander; Ahmed, Ahmed Ashour; Etemadmoghadam, Dariush; Hyland, Sarah J; Australian Ovarian Cancer Study Group; Fazio, Anna de; Fox, Stephen B; Brenton, James D; Bowtell, David D

2007-01-01

p53 is commonly inactivated by mutations in the DNA-binding domain in a wide range of cancers. As mutant p53 often influences response to therapy, effective and rapid methods to scan for mutations in TP53 are likely to be of clinical value. We therefore evaluated the use of high resolution melting (HRM) as a rapid mutation scanning tool for TP53 in tumour samples. We designed PCR amplicons for HRM mutation scanning of TP53 exons 5 to 8 and tested them with DNA from cell lines hemizygous or homozygous for known mutations. We assessed the sensitivity of each PCR amplicon using dilutions of cell line DNA in normal wild-type DNA. We then performed a blinded assessment on ovarian tumour DNA samples that had been previously sequenced for mutations in TP53 to assess the sensitivity and positive predictive value of the HRM technique. We also performed HRM analysis on breast tumour DNA samples with unknown TP53 mutation status. One cell line mutation was not readily observed when exon 5 was amplified. As exon 5 contained multiple melting domains, we divided the exon into two amplicons for further screening. Sequence changes were also introduced into some of the primers to improve the melting characteristics of the amplicon. Aberrant HRM curves indicative of TP53 mutations were observed for each of the samples in the ovarian tumour DNA panel. Comparison of the HRM results with the sequencing results revealed that each mutation was detected by HRM in the correct exon. For the breast tumour panel, we detected seven aberrant melt profiles by HRM and subsequent sequencing confirmed the presence of these and no other mutations in the predicted exons. HRM is an effective technique for simple and rapid scanning of TP53 mutations that can markedly reduce the amount of sequencing required in mutational studies of TP53

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

Epidemiology Study on P53 (Rs1614984 C>T Mutation in Cigarette Smokers

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Dilshad Ahmad

2017-05-01

Full Text Available ABSTRACT Epidemiology data have established that smoking is a prime threat for the cancers, largely lung cancer. Single-nucleotide polymorphisms (SNPs,P53 SNPs have been found to be associated with the predisposition of different cancers. Their decreased expression is reported in breast and lung cancer patients. p53 (rs1614984 had been reported to be linked with the SNPs found associated with breast cancer. The primary aim of this study to determine the association of p53 variant rs1614984 with the cigarette smokers and smoking related cancers in smokers. Among the smokers, 38% were found with CC genotype, 55% were heterozygous CT and 7% were TT, respectively. The homozygous TT genotype was seen in lower percentage of smokers (7% when compared to non-smokers (8% whereas; Significant difference was not observed when encompassed by CC, CT and TT genotypes (χ2 = 4.892, p=0.087. However, CC vs CT genotype showed a significant difference between smokers and non-smokers (p=0.031, OR 1.447 (1.035-2.025 and the dominant model CC vs CT+TT was also significantly different among smoker and non-smokers (p=0.047, OR 1.39 (1.004-1.924. Furthermore, smokers are at the risk of developing variety of diseases including lung cancer. Our finding suggests a higher percentage of heterozygous CT genotype in smokers when compared to non-smokers. Therefore, this finding gives a clue that the transition mutation of C>T (rs1614984 may leads to the lung diseases including cancer in smokers. However, there will be a need of more extensive and elaborated study to set down the aspect of p53(rs1614984 C>T in lung cancer among smokers.

A meta-analysis of the relationship between FGFR3 and TP53 mutations in bladder cancer.

Science.gov (United States)

Neuzillet, Yann; Paoletti, Xavier; Ouerhani, Slah; Mongiat-Artus, Pierre; Soliman, Hany; de The, Hugues; Sibony, Mathilde; Denoux, Yves; Molinie, Vincent; Herault, Aurélie; Lepage, May-Linda; Maille, Pascale; Renou, Audrey; Vordos, Dimitri; Abbou, Claude-Clément; Bakkar, Ashraf; Asselain, Bernard; Kourda, Nadia; El Gaaied, Amel; Leroy, Karen; Laplanche, Agnès; Benhamou, Simone; Lebret, Thierry; Allory, Yves; Radvanyi, François

2012-01-01

TP53 and FGFR3 mutations are the most common mutations in bladder cancers. FGFR3 mutations are most frequent in low-grade low-stage tumours, whereas TP53 mutations are most frequent in high-grade high-stage tumours. Several studies have reported FGFR3 and TP53 mutations to be mutually exclusive events, whereas others have reported them to be independent. We carried out a meta-analysis of published findings for FGFR3 and TP53 mutations in bladder cancer (535 tumours, 6 publications) and additional unpublished data for 382 tumours. TP53 and FGFR3 mutations were not independent events for all tumours considered together (OR = 0.25 [0.18-0.37], p = 0.0001) or for pT1 tumours alone (OR = 0.47 [0.28-0.79], p = 0.0009). However, if the analysis was restricted to pTa tumours or to muscle-invasive tumours alone, FGFR3 and TP53 mutations were independent events (OR = 0.56 [0.23-1.36] (p = 0.12) and OR = 0.99 [0.37-2.7] (p = 0.35), respectively). After stratification of the tumours by stage and grade, no dependence was detected in the five tumour groups considered (pTaG1 and pTaG2 together, pTaG3, pT1G2, pT1G3, pT2-4). These differences in findings can be attributed to the putative existence of two different pathways of tumour progression in bladder cancer: the CIS pathway, in which FGFR3 mutations are rare, and the Ta pathway, in which FGFR3 mutations are frequent. TP53 mutations occur at the earliest stage of the CIS pathway, whereas they occur would much later in the Ta pathway, at the T1G3 or muscle-invasive stage.

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.

Presença da Proteína p53 como Prognóstico de Recidiva/Progressão de Neoplasia Intra-epitelial Vulvar III p53 Protein Overexpression as a Prognostic Marker for Vulvar Intraepithelial Neoplasia III Recurrence/Progression

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Isabel Cristina Chulvis do Val Guimarães

2002-01-01

Full Text Available Objetivo: avaliar o valor da presença da proteína p53 nos casos de recidiva/progressão da neoplasia intra-epitelial vulvar (VIN III. Métodos: foram selecionadas 20 pacientes com VIN III indiferenciada, seguidas semestralmente por período de até quatro anos, divididas em dois grupos: quatorze sem e seis com recidiva/progressão da lesão. Os casos de recidiva/progressão foram distribuídos da seguinte forma: em três pacientes a recidiva ocorreu uma única vez, em duas, houve dupla recorrência e apenas uma evoluiu para carcinoma escamoso. Em ambos os grupos foram avaliados o sítio vulvar acometido e a presença da proteína p53 com análise do padrão de marcação imunohistoquímica. Estudo semelhante foi realizado nos casos de recidiva/progressão além da análise do intervalo de tempo para o surgimento de recidiva/progressão. Resultados: observou-se recidiva da VIN III em 25% dos casos e, em 5%, progressão para carcinoma. O tempo médio de recidiva foi de 24,5 meses. A localização multifocal da lesão primária foi a mais freqüente (50% em ambos os grupos. Na maioria dos casos (87,5%, a recidiva/progressão ocorreu na mesma localização da lesão vulvar primária. A presença da proteína p53 mostrou-se positiva em 50% das lesões primárias de VIN III e em 75% dos casos de recidiva/progressão. Conclusões: a presença da proteína p53 parece desempenhar papel importante na gênese e na predição do curso clínico das VIN III. As recidivas/progressão das VIN III tendem a ocorrer na mesma área da doença inicial, sugerindo a presença de campo molecular alterado.Purpose: to evaluate p53 overexpression value in vulvar intraepithelial neoplasia (VIN III recurrence/progression. Methods: twenty patients with undifferentiated VIN III were selected and followed up every six months for four years and divided into two groups: fourteen without and six with recurrence/progression lesion. The recurrence/progression cases were

Clinical utility of anti-p53 auto-antibody: systematic review and focus on colorectal cancer.

Science.gov (United States)

Suppiah, Aravind; Greenman, John

2013-08-07

Mutation of the p53 gene is a key event in the carcinogenesis of many different types of tumours. These can occur throughout the length of the p53 gene. Anti-p53 auto-antibodies are commonly produced in response to these p53 mutations. This review firstly describes the various mechanisms of p53 dysfunction and their association with subsequent carcinogenesis. Following this, the mechanisms of induction of anti-p53 auto-antibody production are shown, with various hypotheses for the discrepancies between the presence of p53 mutation and the presence/absence of anti-p53 auto-antibodies. A systematic review was performed with a descriptive summary of key findings of each anti-p53 auto-antibody study in all cancers published in the last 30 years. Using this, the cumulative frequency of anti-p53 auto-antibody in each cancer type is calculated and then compared with the incidence of p53 mutation in each cancer to provide the largest sample calculation and correlation between mutation and anti-p53 auto-antibody published to date. Finally, the review focuses on the data of anti-p53 auto-antibody in colorectal cancer studies, and discusses future strategies including the potentially promising role using anti-p53 auto-antibody presence in screening and surveillance.

Relationship among tobacco habits, human papilloma virus (HPV) infection, p53 polymorphism/mutation and the risk of oral squamous cell carcinoma.

Science.gov (United States)

Chakrobarty, Bidyut; Roy, Jay Gopal; Majumdar, Sumit; Uppala, Divya

2014-05-01

The prevalence of oral squamous cell carcinoma (OSCC) has significantly increased over decades in several countries and human papilloma virus (HPV) has been indicated as one of the underlying causes. This suggests that HPV plays a role in the early stages of carcinogenesis but is not a requisite for the maintenance and progression of malignant state. p53 is a tumor suppressor gene that checks the cell and promotes apoptosis and cell repair that can be deactivated by mutations and a viral interaction leading to cancer and individuals with particular polymorphic variant of p53 is more susceptible to HPV-induced carcinogenesis. The present study has been carried out to detect and correlate p53 polymorphism/mutation, HPV DNA in the biopsy samples of oral cancer patients who had tobacco habits.

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

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

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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.

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

Towards Prognostic Profiling of Non-Small Cell Lung Cancer: New Perspectives on the Relevance of Polo-Like Kinase 1 Expression, the TP53 Mutation Status and Hypoxia

Science.gov (United States)

Van den Bossche, Jolien; Deben, Christophe; Op de Beeck, Ken; Deschoolmeester, Vanessa; Hermans, Christophe; De Pauw, Ines; Jacobs, Julie; Van Schil, Paul; Vermorken, Jan Baptist; Pauwels, Patrick; Peeters, Marc; Lardon, Filip; Wouters, An

2017-01-01

Background: Currently, prognosis of non-small cell lung cancer (NSCLC) patients is based on clinicopathological factors, including TNM stage. However, there are considerable differences in patient outcome within a similar staging group, even when patients received identical treatments. In order to improve prognostic predictions and to guide treatment options, additional parameters influencing outcome are required. Polo-like kinase 1 (Plk1), a master regulator of mitotic cell division and the DNA damage response, is considered as a new potential biomarker in this research area. While several studies reported Plk1 overexpression in a broad range of human malignancies, inconsistent results were published regarding the clinical significance hereof. A prognostic panel, consisting of Plk1 and additional biomarkers that are related to the Plk1 pathway, might further improve prediction of patient prognosis. Methods: In this study, we evaluated for the first time the prognostic value of Plk1 mRNA and protein expression in combination with the TP53 mutation status (next generation sequencing), induction of apoptotic cell death (immunohistochemistry for cleaved caspase 3) and hypoxia (immunohistochemistry for carbonic anhydrase IX (CA IX)) in 98 NSCLC adenocarcinoma patients. Results: Both Plk1 mRNA and protein expression and CA IX protein levels were upregulated in the majority of tumor samples. Plk1 mRNA and protein expression levels were higher in TP53 mutant samples, suggesting that Plk1 overexpression is, at least partially, the result of loss of functional p53 (<0.05). Interestingly, the outcome of patients with both Plk1 mRNA and CA IX protein overexpression, who also harbored a TP53 mutation, was much worse than that of patients with aberrant expression of only one of the three markers (p=0.001). Conclusion: The combined evaluation of Plk1 mRNA expression, CA IX protein expression and TP53 mutations shows promise as a prognostic panel in NSCLC patients. Moreover

Avoiding restorative proctocolectomy for colorectal cancer in patients with ulcerative colitis based on preoperative diagnosis involving p53 immunostaining: report of a case.

Science.gov (United States)

Sada, Haruki; Shimomura, Manabu; Hinoi, Takao; Egi, Hiroyuki; Kawaguchi, Koji; Yano, Takuya; Niitsu, Hiroaki; Saitou, Yasufumi; Sawada, Hiroyuki; Miguchi, Masashi; Adachi, Tomohiro; Ohdan, Hideki

2015-03-26

The standard operation for colitic cancer in ulcerative colitis (UC) is restorative proctocolectomy; however, sporadic colorectal cancer (CRC) can coincidentally arise in patients with UC and the optimal procedure remains controversial. Therefore, it is crucial to preoperatively determine whether the CRC in UC is a sporadic or colitic cancer. We report a case of avoiding proctocolectomy for sporadic CRC in a patient with UC based on preoperative diagnosis involving p53 immunostaining. A 73-year-old man with CRC in UC had undergone sigmoid colectomy with lymphadenectomy because of the submucosal deep invasion pathologically after endoscopic mucosal resection. The cancer was diagnosed sporadic cancer preoperatively not only based on the endoscopic, clinical, and histological patterns but also that the colon epithelium was unlikely to develop dysplasia as the circumference and unaffected UC mucosa did not detect p53 protein overexpression. Recent reports have shown that the immunohistochemical detection of p53 protein overexpression can be useful for a differential diagnosis and as a predictor of dysplasia and colitic cancer. The analysis of p53 mutation status based on immunostaining of p53 protein expression in the unaffected UC mucosa can be useful for the decision regarding a surgical procedure for CRC in patients with UC.

Two co-existing germline mutations P53 V157D and PMS2 R20Q promote tumorigenesis in a familial cancer syndrome.

Science.gov (United States)

Wang, Zuoyun; Sun, Yihua; Gao, Bin; Lu, Yi; Fang, Rong; Gao, Yijun; Xiao, Tian; Liu, Xin-Yuan; Pao, William; Zhao, Yun; Chen, Haiquan; Ji, Hongbin

2014-01-01

Germline mutations are responsible for familial cancer syndromes which account for approximately 5-10% of all types of cancers. These mutations mainly occur at tumor suppressor genes or genome stability genes, such as DNA repair genes. Here we have identified a cancer predisposition family, in which eight members were inflicted with a wide spectrum of cancer including one diagnosed with lung cancer at 22years old. Sequencing analysis of tumor samples as well as histologically normal specimens identified two germline mutations co-existing in the familial cancer syndrome, the mutation of tumor suppressor gene P53 V157D and mismatch repair gene PMS2 R20Q. We further demonstrate that P53 V157D and/or PMS2 R20Q mutant promotes lung cancer cell proliferation. These two mutants are capable of promoting colony formation in soft agar as well as tumor formation in transgenic drosophila system. Collectively, these data have uncovered the important role of co-existing germline P53 and PMS2 mutations in the familial cancer syndrome development. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

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

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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.

A meta-analysis of the relationship between FGFR3 and TP53 mutations in bladder cancer.

Directory of Open Access Journals (Sweden)

Yann Neuzillet

Full Text Available TP53 and FGFR3 mutations are the most common mutations in bladder cancers. FGFR3 mutations are most frequent in low-grade low-stage tumours, whereas TP53 mutations are most frequent in high-grade high-stage tumours. Several studies have reported FGFR3 and TP53 mutations to be mutually exclusive events, whereas others have reported them to be independent. We carried out a meta-analysis of published findings for FGFR3 and TP53 mutations in bladder cancer (535 tumours, 6 publications and additional unpublished data for 382 tumours. TP53 and FGFR3 mutations were not independent events for all tumours considered together (OR = 0.25 [0.18-0.37], p = 0.0001 or for pT1 tumours alone (OR = 0.47 [0.28-0.79], p = 0.0009. However, if the analysis was restricted to pTa tumours or to muscle-invasive tumours alone, FGFR3 and TP53 mutations were independent events (OR = 0.56 [0.23-1.36] (p = 0.12 and OR = 0.99 [0.37-2.7] (p = 0.35, respectively. After stratification of the tumours by stage and grade, no dependence was detected in the five tumour groups considered (pTaG1 and pTaG2 together, pTaG3, pT1G2, pT1G3, pT2-4. These differences in findings can be attributed to the putative existence of two different pathways of tumour progression in bladder cancer: the CIS pathway, in which FGFR3 mutations are rare, and the Ta pathway, in which FGFR3 mutations are frequent. TP53 mutations occur at the earliest stage of the CIS pathway, whereas they occur would much later in the Ta pathway, at the T1G3 or muscle-invasive stage.

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.

Mutations in TP53 tumor suppressor gene in wood dust-related sinonasal cancer

DEFF Research Database (Denmark)

Holmila, Reetta; Bornholdt, Jette; Heikkilä, Pirjo

2010-01-01

The causal role of work-related exposure to wood dust in the development of sinonasal cancer has long been established by numerous epidemiologic studies. To study molecular changes in these tumors, we analyzed TP53 gene mutations in 358 sinonasal cancer cases with or without occupational exposure...... affected the ORs only slightly. Smoking did not influence the occurrence of TP53 mutation; however, it was associated with multiple mutations (p = 0.03). As far as we are aware, this is the first study to demonstrate a high prevalence of TP53 mutation-positive cases in a large collection of sinonasal...... cancers with data on occupational exposure. Our results indicate that mutational mechanisms, in particular TP53 mutations, are associated with work-related exposure to wood dust in sinonasal cancer....

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

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.

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

Science.gov (United States)

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

2018-05-23

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

Limited importance of the dominant-negative effect of TP53 missense mutations

International Nuclear Information System (INIS)

Stoczynska-Fidelus, Ewelina; Liberski, Pawel P; Rieske, Piotr; Szybka, Malgorzata; Piaskowski, Sylwester; Bienkowski, Michal; Hulas-Bigoszewska, Krystyna; Banaszczyk, Mateusz; Zawlik, Izabela; Jesionek-Kupnicka, Dorota; Kordek, Radzislaw

2011-01-01

Heterozygosity of TP53 missense mutations is related to the phenomenon of the dominant-negative effect (DNE). To estimate the importance of the DNE of TP53 mutations, we analysed the percentage of cancer cases showing a single heterozygous mutation of TP53 and searched for a cell line with a single heterozygous mutation of this gene. This approach was based on the knowledge that genes with evident DNE, such as EGFR and IDH1, represent nearly 100% of single heterozygous mutations in tumour specimens and cell lines. Genetic analyses (LOH and sequencing) performed for early and late passages of several cell lines originally described as showing single heterozygous TP53 mutations (H-318, G-16, PF-382, MOLT-13, ST-486 and LS-123). Statistical analysis of IARC TP53 and SANGER databases. Genetic analyses of N-RAS, FBXW7, PTEN and STR markers to test cross-contamination and cell line identity. Cell cloning, fluorescence-activated cell sorting and SSCP performed for the PF-382 cell line. A database study revealed TP53 single heterozygous mutations in 35% of in vivo (surgical and biopsy) samples and only 10% of cultured cells (in vitro), although those numbers appeared to be overestimated. We deem that published in vivo TP53 mutation analyses are not as rigorous as studies in vitro, and we did not find any cell line showing a stable, single heterozygous mutation. G16, PF-382 and MOLT-13 cells harboured single heterozygous mutations temporarily. ST-486, H-318 and LS-123 cell lines were misclassified. Specific mutations, such as R175H, R273H, R273L or R273P, which are reported in the literature to exert a DNE, showed the lowest percentage of single heterozygous mutations in vitro (about 5%). We suggest that the currently reported percentage of TP53 single heterozygous mutations in tumour samples and cancer cell lines is overestimated. Thus, the magnitude of the DNE of TP53 mutations is questionable. This scepticism is supported by database investigations showing that retention

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

Assessment and prognostic analysis of EGFR mutations or/and HER2 overexpression in Uygur's Non-small Cell Lung Cancer.

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Shen, Hongli; Du, Guoli; Liu, Zhonghua; Bao, Jianling; Yu, Qin; Jia, Chunli; Liang, Xuelin; Shan, Li

2015-01-01

The epidermal growth factor receptor (EGFR) mutations and human epidermal growth factor receptor HER-2/neu (HER2) have been established roles in the signal transduction pathways leading to cell growth and differentiation. The present study focus on the significance of EGFR mutations combined with HER2 overexpression on survival outcomes in Non-small Cell Lung Cancer patients in Uygur population. A total of 111 consecutive Uygurods: A total of 111 consecutive Cell Lung Cancer under went lung Cell Lung biopsy or surgery at the Affiliated Tumor Hospital of Xin Jiang Medical University between March 2009 and January 2013 were included in this retrospective study. All the patients included had received gefitinib 250 mg once daily. The HER2 expression were evaluated by immunohistochemical staining with score of membranous staining being 0 = none, 1 = weak, 2 = 10-30% cells, 3≥30% cells stained, and Real-time PCR techniques were conducted to detect mutations of EGFR through 21 kinds of human EGFR gene mutation detection kits. A retrospective review of the medical records was analyzed to determine the correlation between the presence of EGFR mutations combined with HER2 overexpression and clinicopathological factors. The overall rate of EGFR mutation was 10.81% (n = 12), which mainly involved exons 19 (83.33%, n = 10), 21 (16.67%, n = 2). The overall rate of HER2 overexpression was 21.62% (n = 24). EGFR mutation combined with HER2 overexpression analysis was performed in 111 patients, with an overall rate of 5.41% (n = 6). Median progression-free survival and overall survival were significantly longer in the EGFR mutations group than in the wild type group (PFS: 10.0±1.5 versus 3.8±1.4 months, P = 0.000; OS: 27.3±2.9 versus 19.1±4.7 months, P = 0.000). The ORR in patients with HER2 overexpression was 29.17%, and 13.80% in those patients with HER2 negative, but no significant difference (P = 0.121). The median PFS and OS in HER2 positive group showed no significant

Involvement of hGLD-2 in cytoplasmic polyadenylation of human p53 mRNA

DEFF Research Database (Denmark)

Glahder, Jacob-Andreas Harald; Norrild, Bodil

2011-01-01

Cytoplasmic polyadenylation is a post-transcriptional mechanism regulating mRNA stability and translation. The human p53 3'-untranslated region (3'-UTR) contains two regions similar to cytoplasmic polyadenylation elements (CPEs) just upstream of the poly(A) hexanucleotide. Evaluation of the p53 CPE......-like elements was performed by luciferase reporter assays, qPCR, and poly(A) assays. Herein, we report the down regulation of a luciferase reporter fused to the p53 3'-UTR, when human CPE-binding protein 1 (hCPEB1) is overexpressed. This inhibition is partially rescued when hCPEB1fused to hGLD-2 [a human...... cytoplasmic poly(A) polymerase] is overexpressed instead. The stability of a luciferase mRNA containing the p53 3'-UTR downstream, is decreased when hCPEB1 is overexpressed as seen by qPCR. Expression of hGLD-2 restores the mRNA stability. This is due to elongation of the poly(A) tail as seen by a PCR...

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

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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

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

Promoter hypermethylation of the DNA repair gene O(6)-methylguanine-DNA methyltransferase is associated with the presence of G:C to A:T transition mutations in p53 in human colorectal tumorigenesis.

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Esteller, M; Risques, R A; Toyota, M; Capella, G; Moreno, V; Peinado, M A; Baylin, S B; Herman, J G

2001-06-15

Defects in DNA repair may be responsible for the genesis of mutations in key genes in cancer cells. The tumor suppressor gene p53 is commonly mutated in human cancer by missense point mutations, most of them G:C to A:T transitions. A recognized cause for this type of change is spontaneous deamination of the methylcytosine. However, the persistence of a premutagenic O(6)-methylguanine can also be invoked. This last lesion is removed in the normal cell by the DNA repair enzyme O(6)-methylguanine-DNA methyltransferase (MGMT). In many tumor types, epigenetic silencing of MGMT by promoter hypermethylation has been demonstrated and linked to the appearance of G to A mutations in the K-ras oncogene in colorectal tumors. To study the relevance of defective MGMT function by aberrant methylation in relation to the presence of p53 mutations, we studied 314 colorectal tumors for MGMT promoter hypermethylation and p53 mutational spectrum. Inactivation of MGMT by aberrant methylation was associated with the appearance of G:C to A:T transition mutations at p53 (Fischer's exact test, two-tailed; P = 0.01). Overall, MGMT methylated tumors displayed p53 transition mutations in 43 of 126 (34%) cases, whereas MGMT unmethylated tumors only showed G:C to A:T changes in 37 of 188 (19%) tumors. A more striking association was found in G:C to A:T transitions in non-CpG dinucleotides; 71% (12 of 17) of the total non-CpG transition mutations in p53 were observed in MGMT aberrantly methylated tumors (Fischer's exact test, two-tailed; P = 0.008). Our data suggest that epigenetic silencing of MGMT by promoter hypermethylation may lead to G:C to A:T transition mutations in p53.

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

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

1997-06-01

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

Expression of p53 protein in Barrett’s adenocarcinoma and adenocarcinoma of the gastric cardia and antrum

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Jovanović Ivan

2005-01-01

Full Text Available Background/Aim. Most studies of esophageal and gastric adenocarcinomas have shown a very high rate of p53 gene mutation and/or protein overexpression, but the influence of the tumor site upon the frequency of p53 protein expression has not been evaluated (gastroesophageal junction, Barret's esophagus, and antrum. The aim of our study was to analyze the correlation between the selected clinico-pthological parameters, and p53 protein overexpression in regards to the particular tumor location. Methods. The material comprised 66 surgical specimens; 10 were Barrett’s carcinomas, 25 adenocarcinomas of the gastric cardia (type II adenocarcinoma of the esophagogastric junction - EGJ, and 31 adenocarcinomas of the antrum. Immunostaining for p53 protein was performed on formalin-fixed, paraffin-embedded tissue sections, using the alkaline phosphatase - antialkaline phosphatase (APAAP method. The cases were considered positive for p53 if at least 5% of the tumor cells expressed this protein by immunostaining. Results. There was no significant difference observed between the studied groups in regards to age, sex, Lauren’s classification and tumor differentiation. There was, however, a significant difference observed in the depth of tumor invasion between Barrrett’s adenocarcinoma and adenocarcinoma of the cardia compared with the adenocarcinoma of the antrum. Namely, at the time of surgery, both Barrett’s adenocarcinomas and adenocarcinomas of the cardia, were significantly more advanced comparing with the adenocarcinomas of the antrum. Overexpression of p53 was found in 40% (4/10 of Barrett’s adenocarcinomas, 72% (18/25 of adenocarcinoma of the cardia and 65% (20/31 of adenocarcinoma of the antrum. No significant differences in p53 expression in relation to sex, type (Lauren of tumor, depth of invasion, lymph node involvement, or tumor differentiation were observed in any of the analyzed groups of tumors. Patients with more advanced Barrett�

TP53 mutational status is a potential marker for risk stratification in Wilms tumour with diffuse anaplasia.

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Mariana Maschietto

Full Text Available The presence of diffuse anaplasia in Wilms tumours (DAWT is associated with TP53 mutations and poor outcome. As patients receive intensified treatment, we sought to identify whether TP53 mutational status confers additional prognostic information.We studied 40 patients with DAWT with anaplasia in the tissue from which DNA was extracted and analysed for TP53 mutations and 17p loss. The majority of cases were profiled by copy number (n = 32 and gene expression (n = 36 arrays. TP53 mutational status was correlated with patient event-free and overall survival, genomic copy number instability and gene expression profiling.From the 40 cases, 22 (55% had TP53 mutations (2 detected only after deep-sequencing, 20 of which also had 17p loss (91%; 18 (45% cases had no detectable mutation but three had 17p loss. Tumours with TP53 mutations and/or 17p loss (n = 25 had an increased risk of recurrence as a first event (p = 0.03, hazard ratio (HR, 3.89; 95% confidence interval (CI, 1.26-16.0 and death (p = 0.04, HR, 4.95; 95% CI, 1.36-31.7 compared to tumours lacking TP53 abnormalities. DAWT carrying TP53 mutations showed increased copy number alterations compared to those with wild-type, suggesting a more unstable genome (p = 0.03. These tumours showed deregulation of genes associated with cell cycle and DNA repair biological processes.This study provides evidence that TP53 mutational analysis improves risk stratification in DAWT. This requires validation in an independent cohort before clinical use as a biomarker.

TP53 mutational status is a potential marker for risk stratification in Wilms tumour with diffuse anaplasia.

Science.gov (United States)

Maschietto, Mariana; Williams, Richard D; Chagtai, Tasnim; Popov, Sergey D; Sebire, Neil J; Vujanic, Gordan; Perlman, Elizabeth; Anderson, James R; Grundy, Paul; Dome, Jeffrey S; Pritchard-Jones, Kathy

2014-01-01

The presence of diffuse anaplasia in Wilms tumours (DAWT) is associated with TP53 mutations and poor outcome. As patients receive intensified treatment, we sought to identify whether TP53 mutational status confers additional prognostic information. We studied 40 patients with DAWT with anaplasia in the tissue from which DNA was extracted and analysed for TP53 mutations and 17p loss. The majority of cases were profiled by copy number (n = 32) and gene expression (n = 36) arrays. TP53 mutational status was correlated with patient event-free and overall survival, genomic copy number instability and gene expression profiling. From the 40 cases, 22 (55%) had TP53 mutations (2 detected only after deep-sequencing), 20 of which also had 17p loss (91%); 18 (45%) cases had no detectable mutation but three had 17p loss. Tumours with TP53 mutations and/or 17p loss (n = 25) had an increased risk of recurrence as a first event (p = 0.03, hazard ratio (HR), 3.89; 95% confidence interval (CI), 1.26-16.0) and death (p = 0.04, HR, 4.95; 95% CI, 1.36-31.7) compared to tumours lacking TP53 abnormalities. DAWT carrying TP53 mutations showed increased copy number alterations compared to those with wild-type, suggesting a more unstable genome (p = 0.03). These tumours showed deregulation of genes associated with cell cycle and DNA repair biological processes. This study provides evidence that TP53 mutational analysis improves risk stratification in DAWT. This requires validation in an independent cohort before clinical use as a biomarker.

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

International Nuclear Information System (INIS)

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

1993-01-01

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

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

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Dadi Jiang

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

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

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

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.

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

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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.

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

A53T-alpha-synuclein overexpression impairs dopamine signaling and striatal synaptic plasticity in old mice.

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Alexander Kurz

2010-07-01

Full Text Available Parkinson's disease (PD, the second most frequent neurodegenerative disorder at old age, can be caused by elevated expression or the A53T missense mutation of the presynaptic protein alpha-synuclein (SNCA. PD is characterized pathologically by the preferential vulnerability of the dopaminergic nigrostriatal projection neurons.Here, we used two mouse lines overexpressing human A53T-SNCA and studied striatal dysfunction in the absence of neurodegeneration to understand early disease mechanisms. To characterize the progression, we employed young adult as well as old mice. Analysis of striatal neurotransmitter content demonstrated that dopamine (DA levels correlated directly with the level of expression of SNCA, an observation also made in SNCA-deficient (knockout, KO mice. However, the elevated DA levels in the striatum of old A53T-SNCA overexpressing mice may not be transmitted appropriately, in view of three observations. First, a transcriptional downregulation of the extraneural DA degradation enzyme catechol-ortho-methytransferase (COMT was found. Second, an upregulation of DA receptors was detected by immunoblots and autoradiography. Third, extensive transcriptome studies via microarrays and quantitative real-time RT-PCR (qPCR of altered transcript levels of the DA-inducible genes Atf2, Cb1, Freq, Homer1 and Pde7b indicated a progressive and genotype-dependent reduction in the postsynaptic DA response. As a functional consequence, long term depression (LTD was absent in corticostriatal slices from old transgenic mice.Taken together, the dysfunctional neurotransmission and impaired synaptic plasticity seen in the A53T-SNCA overexpressing mice reflect early changes within the basal ganglia prior to frank neurodegeneration. As a model of preclinical stages of PD, such insights may help to develop neuroprotective therapeutic approaches.

TRIM65 negatively regulates p53 through ubiquitination

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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.

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

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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.

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

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Fatma Ashour

2018-06-01

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

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

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

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Villiard Éric

2007-09-01

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

p53, erbB-2 and K-ras gene alterations are rare in spontaneous and plutonium-239-induced canine lung neoplasia

International Nuclear Information System (INIS)

Tierney, L.A.; Hahn, F.F.; Lechner, J.F.

1996-01-01

Inhalation of high-linear energy transfer radiation in the form of radon progeny is a suspected cause of human lung cancer. To gain insight into the types of genetic derangements caused by this type of radiation, lung tumors from beagle dogs exposed to 239 PuO 2 and those arising in animals with no known carcinogen exposure were examined for evidence of aberrations in genes known to be altered in lung tumors. Altered expression of the p53 tumor suppressor gene and proto-oncogene erbB-2 proteins (p185 erbB2 ) was evaluated by immunohistochemical analysis of 117 tumors representing different histological types in exposed (n = 80) and unexposed (n = 37) animals. Twenty-eight tumors were analyzed for K-ras proto-oncogene mutations by polymerase chain reaction amplification and direct sequencing. Fourteen percent (16/116) of all lung neoplasms showed elevated nuclear accumulation of p53 protein. Regardless of exposure history, adenosquamous and squamous cell cancers comprised 94% of all tumors with p53 abnormalities. Eighteen percent (21/117) of all tumors had evidence of erbB-2 protein overexpression. K-ras mutations were not detected in codons 12, 13 or 61 of tumors from unexposed (n = 9) or plutonium-exposed dogs (n = 19). These data indicate that p53 and K-ras gene abnormalities as a result of missense mutation are infrequent events in spontaneous and 239 PuO 2 -induced lung neoplasia in this colony of beagle dogs. Alternative mechanisms of gene alteration may be involved in canine pulmonary carcinogenesis. 45 refs., 3 figs., 2 tabs

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

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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.

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

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

2017-10-15

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

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,

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)

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

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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.

Regulation of p53 tetramerization and nuclear export by ARC.

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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.

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

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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.

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

Overexpression of RBBP6, alone or combined with mutant TP53, is predictive of poor prognosis in colon cancer.

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Jian Chen

Full Text Available Retinoblastoma binding protein 6 (RBBP6 plays an important role in chaperone-mediated ubiquitination and interacts with TP53 in carcinogenesis. However, the clinicopathologic significance of RBBP6 expression in colon cancer is unknown; in particular, the prognostic value of RBBP6 combined with TP53 expression has not been explored. Therefore, quantitative real-time PCR and western blot analyses were performed to detect RBBP6 expression in colon cancer tissues. RBBP6 and TP53 expression were assessed by immunohistochemistry in a tissue microarray format, in which the primary colon cancer tissue was paired with noncancerous tissue. Tissue specimens were obtained from 203 patients. We found that RBBP6 was overexpressed in colon tumorous tissues and was significantly associated with clinical stage, depth of tumor invasion, lymph node metastasis (LNM, distant metastasis, and histologic grade. Further studies revealed that a corresponding correlation between RBBP6 overexpression and mutant TP53 was evident in colon cancer (r = 0.450; P<0.001. RBBP6 expression was an independent prognostic factor for overall survival (OS and disease free survival (DFS. Interestingly, patients with tumors that had both RBBP6 overexpression and mutant TP53 protein accumulation relapsed and died within a significantly short period after surgery (P<0.001. Multivariate analysis showed that patients with LNM and patients with both RBBP6- and TP53-positive tumors had extremely poor OS (HR 6.75; 95% CI 2.63-17.35; P<0.001 and DFS (HR 8.08; 95% CI 2.80-23.30; P<0.001. These clinical findings indicate that the assessment of both RBBP6 and mutant TP53 expression will be helpful in predicting colon cancer prognosis.

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

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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.

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

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

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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.

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,

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

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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

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...

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 ...

A Swedish family with de novo alpha-synuclein A53T mutation: evidence for early cortical dysfunction

DEFF Research Database (Denmark)

Puschmann, Andreas; Ross, Owen A; Vilariño-Güell, Carles

2009-01-01

A de novo alpha-synuclein A53T (p.Ala53 Th; c.209G > A) mutation has been identified in a Swedish family with autosomal dominant Parkinson's disease (PD). Two affected individuals had early-onset (before 31 and 40 years), severe levodopa-responsive PD with prominent dysphasia, dysarthria, and cog......A de novo alpha-synuclein A53T (p.Ala53 Th; c.209G > A) mutation has been identified in a Swedish family with autosomal dominant Parkinson's disease (PD). Two affected individuals had early-onset (before 31 and 40 years), severe levodopa-responsive PD with prominent dysphasia, dysarthria......) and the Greek-American Family H kindreds. One unaffected family member carried the mutation haplotype without the c.209A mutation, strongly suggesting its de novo occurrence within this family. Furthermore, a novel mutation c.488G > A (p.Arg163His; R163H) in the presenilin-2 (PSEN2) gene was detected...

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

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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.

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.

P53-miR-191-SOX4 regulatory loop affects apoptosis in breast cancer.

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Sharma, Shivani; Nagpal, Neha; Ghosh, Prahlad C; Kulshreshtha, Ritu

2017-08-01

miRNAs have emerged as key participants of p53 signaling pathways because they regulate or are regulated by p53. Here, we provide the first study demonstrating direct regulation of an oncogenic miRNA, miR-191-5p, by p53 and existence of a regulatory feedback loop. Using a combination of qRT-PCR, promoter-luciferase, and chromatin-immunoprecipitation assays, we show that p53 brings about down-regulation of miR-191-5p in breast cancer. miR-191-5p overexpression brought about inhibition of apoptosis in breast cancer cell lines (MCF7 and ZR-75) as demonstrated by reduction in annexin-V stained cells and caspase 3/7 activity, whereas miR-191-5p down-regulation showed the opposite. We further unveiled that SOX4 was a direct target of miR-191-5p. SOX4 overexpression was shown to increase p53 protein levels in MCF7 cells. miR-191-5p overexpression brought about down-regulation of SOX4 and thus p53 levels, suggesting the existence of a regulatory feedback loop. Breast cancer treatment by doxorubicin, an anti-cancer drug, involves induction of apoptosis by p53; we thus wanted to check whether miR-191-5p affects doxorubicin sensitivity. Interestingly, Anti-miR-191 treatment significantly decreased the IC50 of the doxorubicin drug and thus sensitized breast cancer cells to doxorubicin treatment by promoting apoptosis. Overall, this work highlights the importance of the p53-miR-191- SOX4 axis in the regulation of apoptosis and drug resistance in breast cancer and offers a preclinical proof-of-concept for use of an Anti-miR-191 and doxorubicin combination as a rational approach to pursue for better breast cancer treatment. © 2017 Sharma et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

A STUDY OF P53 EXPRESSION IN UROTHELIAL NEOPLASMS OF URINARY BLADDER

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G. Sathish Kumar

2017-07-01

Full Text Available BACKGROUND Urothelial Cell Carcinoma (UCC of urinary bladder is the seventh commonest cancer wordwide.1 At initial diagnosis, 30% of UCC display solid and invasive growth patterns and are locally advanced or metastatic at the time of diagnosis. 70% of tumours are noninvasive papillary UCC confined to the epithelium and subepithelial connective tissue,2 which can be managed by endoscopic resection. A significant number of post-resected cases, progress for recurrence of tumour and infiltration to muscle layers. Invasive bladder cancer has high morbidity and uniform mortality when it is metastatic. There are no effective tools to predict aggressiveness of tumour, so that these cases can be managed more successfully. Mutated Tp53/p53 is the genetic abnormality most frequently associated with UCC and related to cell transformation, malignancy and high recurrence rates.2 MATERIALS AND METHODS This is a descriptive study conducted in the departments of urology and pathology and during the period of March 2014 to February 2015. All consecutive cystoscopic biopsies, Trans urethral resection of bladder tumour (TURBT and radical cystectomy specimens histopathologically diagnosed as UCC were included in the study. p53 expression was assessed by immunohistochemistry. Positive and negative controls were used. Bivariate analysis was done using Chi-square test in all cases. RESULTS A total of 80 cases were analysed. Significant association of p53 expression was found in higher grades of tumour. Also, noted relation of p53 mutation with tumour size, multifocality, multiplicity, muscle invasion and tumour stage, which were statistically not significant. CONCLUSION Bladder tumour grade shows significant association to p53 expression. Papillary neoplasm of low malignant potential (PUNLMP tumours are negative for p53, and in the present study, there was significant difference in p53 over expression low-grade papillary UCC compared with PUNLMP. 90% of low

TP53 mutations in serous tubal intraepithelial carcinoma and concurrent pelvic high-grade serous carcinoma—evidence supporting the clonal relationship of the two lesions

Science.gov (United States)

Kuhn, Elisabetta; Kurman, Robert J; Vang, Russell; Sehdev, Ann Smith; Han, Guangming; Soslow, Robert; Wang, Tian-Li; Shih, Ie-Ming

2016-01-01

Serous tubal intraepithelial carcinomas (STICs) have been proposed to be the most likely precursor of ovarian, tubal and ‘primary peritoneal’ (pelvic) high-grade serous carcinoma (HGSC). As somatic mutation of TP53 is the most common molecular genetic change of ovarian HGSC, occurring in more than 95% of cases, we undertook a mutational analysis of 29 pelvic HGSCs that had concurrent STICs to demonstrate the clonal relationship of STICs and HGSCs. In addition, we correlated the mutational data with p53 immunostaining to determine the role of p53 immunoreactivity as a surrogate for TP53 mutations in histological diagnosis. Somatic TP53 mutations were detected in all 29 HGSCs analysed and the identical mutations were detected in 27 of 29 pairs of STICs and concurrent HGSCs. Missense mutations were observed in 61% of STICs and frameshift/splicing junction/nonsense mutations in 39%. Interestingly, there were two HGSCs with two distinctly different TP53 mutations each, but only one of the mutations was detected in the concurrent STICs. Missense mutations were associated with intense and diffuse (≥ 60%) p53 nuclear immunoreactivity, while most of the null mutations were associated with complete loss of p53 staining (p STIC and pelvic HGSC and demonstrate the utility of p53 immunostaining as a surrogate for TP53 mutation in the histological diagnosis of STIC. In this regard, it is important to appreciate the significance of different staining patterns. Specifically, strong diffuse staining correlates with a missense mutation, whereas complete absence of staining correlates with null mutations. PMID:21990067

A novel natural killer cell line (KHYG-1) from a patient with aggressive natural killer cell leukemia carrying a p53 point mutation.

Science.gov (United States)

Yagita, M; Huang, C L; Umehara, H; Matsuo, Y; Tabata, R; Miyake, M; Konaka, Y; Takatsuki, K

2000-05-01

We present the establishment of a natural killer (NK) leukemia cell line, designated KHYG-1, from the blood of a patient with aggressive NK leukemia, which both possessed the same p53 point mutation. The immunophenotype of the primary leukemia cells was CD2+, surface CD3-, cytoplasmic CD3epsilon+, CD7+, CD8alphaalpha+, CD16+, CD56+, CD57+ and HLA-DR+. A new cell line (KHYG-1) was established by culturing peripheral leukemia cells with 100 units of recombinant interleukin (IL)-2. The KHYG-1 cells showed LGL morphology with a large nucleus, coarse chromatin, conspicuous nucleoli, and abundant basophilic cytoplasm with many azurophilic granules. The immunophenotype of KHYG-1 cells was CD1-, CD2+, surface CD3-, cytoplasmic CD3epsilon+, CD7+, CD8alphaalpha+, CD16-, CD25-, CD33+, CD34-, CD56+, CD57-, CD122+, CD132+, and TdT-. Southern blot analysis of these cells revealed a normal germline configuration for the beta, delta, and gamma chains of the T cell receptor and the immunoglobulin heavy-chain genes. Moreover, the KHYG-1 cells displayed NK cell activity and IL-2-dependent proliferation in vitro, suggesting that they are of NK cell origin. Epstein-Barr virus (EBV) DNA was not detected in KHYG-1 cells by Southern blot analysis with a terminal repeat probe from an EBV genome. A point mutation in exon 7 of the p53 gene was detected in the KHYG-1 cells by PCR/SSCP analysis, and direct sequencing revealed the conversion of C to T at nucleotide 877 in codon 248. The primary leukemia cells also carried the same point mutation. Although the precise role of the p53 point mutation in leukemogenesis remains to be clarified, the establishment of an NK leukemia cell line with a p53 point mutation could be valuable in the study of leukemogenesis.

Frequency of Somatic TP53 Mutations in Combination with Known Pathogenic Mutations in Colon Adenocarcinoma, Non–Small Cell Lung Carcinoma, and Gliomas as Identified by Next-Generation Sequencing

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Zahra Shajani-Yi

2018-03-01

Full Text Available The tumor suppressor gene TP53 is the most frequently mutated gene in human cancer. It encodes p53, a DNA-binding transcription factor that regulates multiple genes involved in DNA repair, metabolism, cell cycle arrest, apoptosis, and senescence. TP53 is associated with human cancer by mutations that lead to a loss of wild-type p53 function as well as mutations that confer alternate oncogenic functions that enable them to promote invasion, metastasis, proliferation, and cell survival. Identifying the discrete TP53 mutations in tumor cells may help direct therapies that are more effective. In this study, we identified the frequency of individual TP53 mutations in patients with colon adenocarcinoma (48%, non–small cell lung carcinoma (NSCLC (36%, and glioma/glioblastoma (28% at our institution using next-generation sequencing. We also identified the occurrence of somatic mutations in numerous actionable genes including BRAF, EGFR, KRAS, IDH1, and PIK3CA that occurred concurrently with these TP53 mutations. Of the 480 tumors examined that contained one or more mutations in the TP53 gene, 219 were colon adenocarcinomas, 215 were NSCLCs, and 46 were gliomas/glioblastomas. Among the patients positive for TP53 mutations diagnosed with colon adenocarcinoma, 50% also showed at least one mutation in pathogenic genes of which 14% were BRAF, 33% were KRAS, and 3% were NRAS. Forty-seven percent of NSCLC patients harboring TP53 mutations also had a mutation in at least one actionable pathogenic variant with the following frequencies: BRAF: 4%, EGFR: 10%, KRAS: 28%, and PIK3CA: 4%. Fifty-two percent of patients diagnosed with glioma/glioblastoma with a positive TP53 mutation had at least one concurrent mutation in a known pathogenic gene of which 9% were CDKN2A, 41% were IDH1, and 11% were PIK3CA.

Using an international p53 mutation database as a foundation for an online laboratory in an upper level undergraduate biology class.

Science.gov (United States)

Melloy, Patricia G

2015-01-01

A two-part laboratory exercise was developed to enhance classroom instruction on the significance of p53 mutations in cancer development. Students were asked to mine key information from an international database of p53 genetic changes related to cancer, the IARC TP53 database. Using this database, students designed several data mining activities to look at the changes in the p53 gene from a number of perspectives, including potential cancer-causing agents leading to particular changes and the prevalence of certain p53 variations in certain cancers. In addition, students gained a global perspective on cancer prevalence in different parts of the world. Students learned how to use the database in the first part of the exercise, and then used that knowledge to search particular cancers and cancer-causing agents of their choosing in the second part of the exercise. Students also connected the information gathered from the p53 exercise to a previous laboratory exercise looking at risk factors for cancer development. The goal of the experience was to increase student knowledge of the link between p53 genetic variation and cancer. Students also were able to walk a similar path through the website as a cancer researcher using the database to enhance bench work-based experiments with complementary large-scale database p53 variation information. © 2014 The International Union of Biochemistry and Molecular Biology.

Disruption of the MDM2-p53 interaction strongly potentiates p53-dependent apoptosis in cisplatin-resistant human testicular carcinoma cells via the Fas/FasL pathway

NARCIS (Netherlands)

Koster, R.; Timmer-Bosscha, H.; Bischoff, R.; Gietema, J. A.; de Jong, S.

Wild-type p53 has a major role in the response and execution of apoptosis after chemotherapy in many cancers. Although high levels of wild-type p53 and hardly any TP53 mutations are found in testicular cancer (TC), chemotherapy resistance is still observed in a significant subgroup of TC patients.

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.

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)

Cyclophilin B induces chemoresistance by degrading wild type p53 via interaction with MDM2 in colorectal cancer.

Science.gov (United States)

Choi, Tae Gyu; Nguyen, Minh Nam; Kim, Jieun; Jo, Yong Hwa; Jang, Miran; Nguyen, Ngoc Ngo Yen; Yun, Hyeong Rok; Choe, Wonchae; Kang, Insug; Ha, Joohun; Tang, Dean G; Kim, Sung Soo

2018-06-06

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Chemoresistance is a major problem for effective therapy in CRC. Here, we investigated the mechanism by which peptidylprolyl isomerase B (PPIB; cyclophilin B, CypB) regulates chemoresistance in CRC. We found that CypB is a novel wild type p53 (p53WT)-inducible gene but a negative regulator of p53WT in response to oxaliplatin treatment. Overexpression of CypB shortens the half-life of p53WT and inhibits oxaliplatin-induced apoptosis in CRC cells, whereas knockdown of CypB lengthens the half-life of p53WT and stimulates p53WT dependent apoptosis. CypB interacts directly with MDM2, and enhances MDM2-dependent p53WT ubiquitination and degradation. Furthermore, we firmly validated using bioinformatics analyses that overexpression of CypB is associated with poor prognosis in CRC progression and chemoresistance. Hence, we suggest a novel mechanism of chemoresistance caused by overexpressed CypB, which may help to develop new anti-cancer drugs. We also propose that CypB may be utilized as a predictive biomarker in CRC patients. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

TP53 mutations in serous tubal intraepithelial carcinoma and concurrent pelvic high-grade serous carcinoma--evidence supporting the clonal relationship of the two lesions.

Science.gov (United States)

Kuhn, Elisabetta; Kurman, Robert J; Vang, Russell; Sehdev, Ann Smith; Han, Guangming; Soslow, Robert; Wang, Tian-Li; Shih, Ie-Ming

2012-02-01

Serous tubal intraepithelial carcinomas (STICs) have been proposed to be the most likely precursor of ovarian, tubal and 'primary peritoneal' (pelvic) high-grade serous carcinoma (HGSC). As somatic mutation of TP53 is the most common molecular genetic change of ovarian HGSC, occurring in more than 95% of cases, we undertook a mutational analysis of 29 pelvic HGSCs that had concurrent STICs to demonstrate the clonal relationship of STICs and HGSCs. In addition, we correlated the mutational data with p53 immunostaining to determine the role of p53 immunoreactivity as a surrogate for TP53 mutations in histological diagnosis. Somatic TP53 mutations were detected in all 29 HGSCs analysed and the identical mutations were detected in 27 of 29 pairs of STICs and concurrent HGSCs. Missense mutations were observed in 61% of STICs and frameshift/splicing junction/nonsense mutations in 39%. Interestingly, there were two HGSCs with two distinctly different TP53 mutations each, but only one of the mutations was detected in the concurrent STICs. Missense mutations were associated with intense and diffuse (≥ 60%) p53 nuclear immunoreactivity, while most of the null mutations were associated with complete loss of p53 staining (p STIC and pelvic HGSC and demonstrate the utility of p53 immunostaining as a surrogate for TP53 mutation in the histological diagnosis of STIC. In this regard, it is important to appreciate the significance of different staining patterns. Specifically, strong diffuse staining correlates with a missense mutation, whereas complete absence of staining correlates with null mutations. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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.

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).

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

TP53 mutations in ovarian carcinomas from sporadic cases and carriers of two distinct BRCA1 founder mutations; relation to age at diagnosis and survival

International Nuclear Information System (INIS)

Kringen, Pedro; Wang, Yun; Dumeaux, Vanessa; Kristensen, Gunnar; Borresen-Dale, Anne-Lise; Dorum, Anne

2005-01-01

Ovarian carcinomas from 30 BRCA1 germ-line carriers of two distinct high penetrant founder mutations, 20 carrying the 1675delA and 10 the 1135insA, and 100 sporadic cases were characterized for somatic mutations in the TP53 gene. We analyzed differences in relation to BRCA1 germline status, TP53 status, survival and age at diagnosis, as previous studies have not been conclusive. DNA was extracted from paraffin embedded formalin fixed tissues for the familial cases, and from fresh frozen specimen from the sporadic cases. All cases were treated at our hospital according to protocol. Mutation analyses of exon 2 – 11 were performed using TTGE, followed by sequencing. Survival rates for BRCA1-familial cases with TP53 mutations were not significantly lower than for familial cases without TP53 mutations (p = 0.25, RR = 1.64, 95% CI [0.71–3.78]). Median age at diagnosis for sporadic (59 years) and familial (49 years) cases differed significantly (p < 0.001) with or without TP53 mutations. Age at diagnosis between the two types of familial carriers were not significantly different, with median age of 47 for 1675delA and 52.5 for 1135insA carriers (p = 0.245). For cases ≥50 years at diagnosis, a trend toward longer survival for sporadic over familial cases was observed (p = 0.08). The opposite trend was observed for cases <50 years at diagnosis. There do not seem to be a protective advantage for familial BRCA1 carriers without TP53 mutations over familial cases with TP53 mutations. However, there seem to be a trend towards initial advantage in survival for familial cases compared to sporadic cases diagnosed before the age of 50 both with and without TP53 mutations. However, this trend diminishes over time and for cases diagnosed ≥50 years the sporadic cases show a trend towards an advantage in survival over familial cases. Although this data set is small, if confirmed, this may be a link in the evidence that the differences in ovarian cancer survival reported, are

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

DEFF Research Database (Denmark)

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

2016-01-01

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

The relationship among human papilloma virus infection, survivin, and p53 gene in lung squamous carcinoma tissue

International Nuclear Information System (INIS)

Yue-Hua Wang; De-jie Chen; Tie-Nan Yi

2010-01-01

To study the relationship between the infection of human papillomavirus (HPV) type 16, type 18, the expression of survivin, and the mutation of p53 gene in lung squamous carcinoma tissue for the research of pathogenesis of lung carcinoma.This study was carried out at the Laboratory of Molecular Biology, Xiangfan Central Hospital of Hubei Province, China from September 2008 to May 2010. Forty-five specimens of lung squamous carcinoma tissue confirmed by histopathology were the excisional specimens taken by the Thoracic Surgery of Xiangfan Central Hospital. Normal tissue, closely adjacent to the fresh carcinoma specimens, was used as the control group for p53 gene mutation analysis. Sixteen surgical excisional specimens of benign lung disease were used as a control group of non-carcinomatous diseases. Human papillomavirus DNA were detected by polymerase chain reaction (PCR), and we used the PCR-single-strand conformation polymorphism-ethidium bromide (PCR-SSCP-EB) method to detect the mutations of the p53 gene. The expression of the survivin gene was detected by immunohistochemistry methods. Approximately 68.9% of 45 lung squamous carcinoma tissue had p53 gene mutations. The mutation rate of exon 5-8 p53 were 15.6%, 17.8%, 15.6% and 20%. Approximately 42.2% of lung squamous cell carcinoma samples were shown to be positive for HPV DNA expression and 62.2% were positive for survivin expression. There was an inverse correlation between the presence of HPV infections and mutations of p53 gene; and the mutations of p53 gene and expression of survivin had a positive relationship. Mutation of p53 gene and HPV infection may facilitate each other in the generation of lung squamous cell carcinoma. Abnormal expression of the survivin gene may take part in the onset and progression of lung squamous cell carcinoma (Author).

Depletion of pro-oncogenic RUNX2 enhances gemcitabine (GEM) sensitivity of p53-mutated pancreatic cancer Panc-1 cells through the induction of pro-apoptotic TAp63.

Science.gov (United States)

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

2016-11-01

Recently, we have described that siRNA-mediated silencing of runt-related transcription factor 2 (RUNX2) improves anti-cancer drug gemcitabine (GEM) sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells through the augmentation of p53 family TAp63-dependent cell death pathway. In this manuscript, we have extended our study to p53-mutated human pancreatic cancer Panc-1 cells. According to our present results, knockdown of mutant p53 alone had a marginal effect on GEM-mediated cell death of Panc-1 cells. We then sought to deplete RUNX2 using siRNA in Panc-1 cells and examined its effect on GEM sensitivity. Under our experimental conditions, RUNX2 knockdown caused a significant enhancement of GEM sensitivity of Panc-1 cells. Notably, GEM-mediated induction of TAp63 but not of TAp73 was further stimulated in RUNX2-depleted Panc-1 cells, indicating that, like AsPC-1 cells, TAp63 might play a pivotal role in the regulation of GEM sensitivity of Panc-1 cells. Consistent with this notion, forced expression of TAp63α in Panc-1 cells promoted cell cycle arrest and/or cell death, and massively increased luciferase activities driven by TAp63-target gene promoters such as p21WAF1 and NOXA. In addition, immunoprecipitation experiments indicated that RUNX2 forms a complex with TAp63 in Panc-1 cells. Taken together, our current observations strongly suggest that depletion of RUNX2 enhances the cytotoxic effect of GEM on p53-mutated Panc-1 cells through the stimulation of TAp63-dependent cell death pathway even in the presence of a large amount of pro-oncogenic mutant p53, and might provide an attractive strategy to treat pancreatic cancer patients with p53 mutations.

Apoptosis in spermatogonia irradiated P53 null mice

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