p53 codon 72 polymorphism, DNA damage and repair, and risk of non-melanoma skin cancer

A very common polymorphism of p53, that of codon 72, codes either for a proline (P72) or an arginine (R72). The two alleles differ in their biological properties: P72 is a stronger inducer of p21, while R72 induces 5-10 times more apoptosis. It is not known, however, whether this polymorphism influences genome stability. The influence of p53 codon 72 polymorphism on cancer risk has been studied for different types of cancer with mixed and inconsistent results. With respect to sporadic non-melanoma skin cancer (NMSC), there are few studies, with small sample sizes, and none in a Latinoamerican population. These studies have found no association between p53 genotype at codon 72 and NMSC. We analyzed whether p53 codon 72 genotype influences genomic stability and the sensitivity of cells to UVB. We also carried out a case-control study of NMSC in a Mexican population which included 204 BCC cases, 42 SCC cases, and 238 controls. There was no association between p53 genotype and basal levels of DNA damage, oxidative DNA damage sensitivity, or DNA repair capacity. R72 dominantly increased the in vitro sensitivity of cells to UVB-induced apoptosis. There was no significant association either between p53 genotype and basal cell carcinoma (BCC), squamous cell carcinoma (SCC) or both combined.     

湖南地区汉族人群p53 基因第72 位密码子多态性与宫颈鳞癌的相关性

目的:探讨宫颈组织p53基因第72位密码子的多态性及分析第72位密码子的多态性与湖南地区汉族人群宫颈鳞癌的相关性。方法:采用PCR方法扩增101例正常宫颈和150例宫颈鳞癌石蜡组织p53基因第72位密码子基因,回收目的片段进行测序。采用SPSS 11.5软件分析p53基因第72位密码子的多态性。结果:p53第72位密码子基因测序结果显示,在宫颈鳞癌组织中Arg/Arg、Pro/Pro、Arg/Pro所占比例分别为40.66%、16.67%、42.67%;在正常宫颈组织中Arg/Arg、Pro/Pro、Arg/Pro所占比例分别为47.53%、7.92%、44.55%。统计学分析结果显示,Arg/Arg和Arg/Pro基因型在宫颈鳞癌和对照组中的表达差异没有统计学意义(P>0.05);Pro/Pro基因型在宫颈鳞癌组中所占比例显著高于正常宫颈组织(P<0.05)。结论:p53基因第72位密码子Pro/pro基因型是湖南地区女性发生宫颈鳞癌易感因素。     

湖南地区汉族人群p53基因第72位密码子多态性与宫颈鳞癌的相关性

目的：探讨宫颈组织p53基因第72位密码子的多态性及分析第72位密码子的多态性与湖南地区汉族人群宫颈鳞癌的相关性。方法：采用PCR方法扩增101例正常宫颈和150例宫颈鳞癌石蜡组织p53基因第72位密码子基因,回收目的片段进行测序。采用SPSS11．5软件分析p53基因第72位密码子的多态性。结果：p53第72位密码子基因测序结果显示,在宫颈鳞癌组织中Arg／Arg、Pro／Pro、Arg／Pro所占比例分别为40．66％、16．67％、42．67％;在正常宫颈组织中Arg／Arg、Pro／Pro、Arg／Pro所占比例分别为47．53％、7．92％、44．55％。统计学分析结果显示,Arg／Arg和Arg／Pro基因型在宫颈鳞癌和对照组中的表达差异没有统计学意义（P〉0．05）;Pro／Pro基因型在宫颈鳞癌组中所占比例显著高于正常宫颈组织（P〈0．05）。结论：p53基因第72位密码子Pro／pro基因型是湖南地区女性发生宫颈鳞癌易感因素。     

TP53 codon 72 polymorphism does not affect risk of cervical cancer in patients from The Gambia

AIMS: A case-control study was performed to investigate the relationship between cervical cancer and TP53 polymorphism at codon 72 in young black African women from The Gambia. MATERIALS AND METHODS: The TP53 polymorphism at codon 72 was examined by PCR amplification and SSCP analysis in 40 patients with primary cervical cancer and in 20 healthy women of the same age and from the same geographical area. The occurrence of TP53 polymorphism in combination with the HPV-16 E6 genotype (assayed by PCR) was evaluated. RESULTS: The distribution of TP53 genotypes in cervical cancer patients and in the control group was not statistically different (p = 0.45) and homozygosity for argine at residue 72 was not associated with cervical cancer (odds ratio: 1.24; 95% confidence interval 0.21-9.16). Similarly, a different genotype distribution, cervical cancer and presence of HPV-16 E6 were not observed. CONCLUSIONS:These results cannot rule out an association between TP53 polymorphism at codon 72, HPV infection and the etiology of cervical cancer in this population sample.     

Association of the p53 codon 72 polymorphism to gastric cancer risk in a hight risk population of Costa Rica

Gastric cancer is the second most common cancer associated death cause worldwide. Several factors have been associated with higher risk to develop gastric cancer, among them genetic predisposition. The p53 gene has a polymorphism located at codon 72. which has been associated with higher risk of several types of cancer, including gastric cancer. The aim of this study was to determine the association of p53, codon 72 polymorphism. with the risk of gastric cancer and pre-malignant lesions in a high-risk population from Costa Rica. The genotyping was carried out by PCR-RFLP in 58 gastric cancer patients, 99 controls and 41 individuals classified as group I or II. according to the Japanese histological classification. No association was found for p53. codon 72 polymorphism with neither the risk of gastric cancer nor the risk of less severe gastric lesions in the studied population. Based on this study and taking into account other studies carried out with p53, codon 72 polymorphism. the role of this polymorphismn in the development of gastric cancer remains unclear. De novo mutations on p53 gene produced during neoplasic development of this disease might play a greater role than germinal polymorphisms of the gene. Other polymorphic genes have been associated with higher risk to develop gastric cancer.     

CD8+ T cell recognition of polymorphic wild-type sequence p5365–73 peptides in squamous cell carcinoma of the head and neck

The TP53 tumor suppressor gene contains a well-studied polymorphism that encodes either proline (P) or arginine (R) at codon 72, and over half of the world’s population is homozygous for R at this codon. The wild-type sequence (wt) p53 peptide, p53_65–73, has been identified as a CD8+ T cell-defined tumor antigen for use in broadly applicable cancer vaccines. However, depending on the TP53 codon 72 polymorphism of the recipient, the induced responses to the peptides incorporating R (p53_72R) or P (p53_72P) can be “self” or “non-self.” Thus, we sought to determine which wt p53_65–73 peptide should be used in wt p53-based cancer vaccines. Despite similar predicted HLA-A2-binding affinities, the p53_72P peptide was more efficient than the p53_72R peptide in HLA-A2 stabilization assays. In vitro stimulation (IVS) of CD8+ T cells obtained from healthy HLA-A2⁺ donors with these two peptides led to the generation of CD8+ T cell effectors in one-third of the samples tested, at a frequency similar to the responsiveness to other wt p53 peptides. Interestingly, regardless of their p53 codon 72 genotype, CD8+ T cells stimulated with either p53_72P or p53_72R peptide were cross-reactive against T2 cells pulsed with either peptide, as well as HLA-A2⁺ head and neck cancer (HNC) cell lines presenting p53_72P and/or p53_72R peptides for T cell recognition. Therefore, the cross-reactivity of CD8+ T cells for the polymorphic wt p53_65–73 peptides, irrespective of their p53 codon 72 polymorphism, suggests that employing either peptide in wt p53-based vaccines can result in efficient targeting of this epitope.     

The codon 47 polymorphism in p53 is functionally significant

In addition to a common polymorphism at codon 72, the p53 tumor suppressor gene also contains a rare single nucleotide polymorphism at amino acid 47. Wild type p53 encodes proline at this residue, but in <5% of African Americans, this amino acid is serine. Notably, phosphorylation of the adjacent serine 46 by the proline-directed kinase p38 MAPK is known to greatly enhance the ability of p53 to induce apoptosis. Here we showed that the serine 47 polymorphic variant, which replaces the proline residue necessary for recognition by proline-directed kinases, is a markedly poorer substrate for phosphorylation on serine 46 by p38 MAPK. Consistent with this finding, we showed that the serine 47 variant has up to 5-fold decreased ability to induce apoptosis compared with wild type p53. Mechanistically, we found that this variant has decreased ability to transactivate two p53 target genes, p53AIP1 and PUMA, but not other p53 response genes; this is the first time that phosphorylation of serine 46 has been implicated in transactivation of PUMA by p53. Down-regulation of PUMA in cells with wild type p53 using short interfering RNAs reduced apoptosis in these cells to a level comparable to that in cells containing the serine 47 variant. The combined data indicated that, like the codon 72 polymorphism, the codon 47 polymorphism of p53 is functionally significant and may play a role in cancer risk, progression, and the efficacy of therapy.     

Polymorphism at codon 72 of the p53 gene in human acute myelogenous leukemia.

A common polymorphism at codon 72 of the p53 gene in patients with acute myelogenous leukemia (AML) was analyzed by single-strand conformation polymorphism assay and sodium dodecyl sulfate polyacrylamide-gel electrophoresis of immunoprecipitated 35S-labeled P53 protein. No association between this polymorphism and a marked predisposition to AML was found. The half-lives of these two polymorphic forms of P53 were equivalent in normal phytohemagglutinin-stimulated lymphocytes, while the P53 Pro72 isoform was found to be twice as stable as the Arg72 isoform in Daudi cells.     

Meta-analysis demonstrates no association between p53 codon 72 polymorphism and prostate cancer risk

We examined whether p53 codon 72 polymorphism confers prostate cancer risk by conducting a meta-analysis. Two investigators independently searched the Pubmed, Embase and CBM databases. This meta-analysis was made of seven case-control studies, that included 892 prostate cancer cases and 1020 healthy controls. Meta-analysis results based on all the studies showed no significant association between p53 codon 72 polymorphism and prostate cancer risk in the comparisons of Pro allele vs Arg allele; Pro/Pro + Pro/Arg vs Arg/Arg; Pro/Pro vs Pro/Arg + Arg/Arg; Pro/Pro vs Arg/Arg, and Pro/Arg vs Arg/Arg [odds ratio (OR) = 1.09, 95% confidence interval (CI) = 0.87-1.36, P = 0.47; OR = 1.22, 95%CI = 0.86-1.73, P = 0.27; OR = 1.03, 95%CI = 0.62-1.72, P = 0.91; OR = 1.22, 95%CI = 0.66-2.26, P = 0.52; OR = 1.25, 95%CI = 0.84-1.87, P = 0.27, respectively]. In the subgroup analysis by ethnicity, no association was found between p53 codon 72 polymorphism and prostate cancer risk both in Caucasian and Asian populations. We found no association between p53 codon 72 polymorphism and prostate cancer risk.     

Association of TP53 mutation, p53 overexpression, and p53 codon 72 polymorphism with susceptibility to apoptosis in adult patients with diffuse astrocytomas

Clarification of TP53 alterations is important to understand the mechanisms underlying the development of diffuse astrocytomas. It has been suggested that the alleles of TP53 at codon 72 differ in their ability to induce apoptosis in human cancers. The aim of this study was to analyze the possible association of TP53 mutation, p53 overexpression, and p53 codon 72 polymorphism with susceptibility to apoptosis in adult Brazilian patients with diffuse astrocytomas. We analyzed 56 surgical specimens of diffuse astrocytomas for alterations of TP53, using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) direct sequencing. p53 and cleaved caspase 3 protein expression were assessed by immunohistochemistry. We found TP53 mutations in 19.6% (11 out of 56) of tumors tested, with the lowest mutation rate found in the cases of glioblastomas (8.8%) (p = 0.03). Only 16.1% of tumors tested showed cleaved caspase 3-positive staining, demonstrating that apoptosis is very inhibited in these tumors. All tumors having TP53 mutation and p53 accumulation had no expression of cleaved caspase 3. Additionally, no association was observed in tumors having proline and arginine alleles and expression of cleaved caspase 3. We concluded that clarification of the TP53 alterations allows a better understanding of the mechanisms involved in the progression of diffuse astrocytomas, and the allele status at codon 72 was not associated with apoptosis in these tumors.     

Meta-analysis of an association of codon 72 polymorphisms of the p53 gene with increased endometrial cancer risk

Polymorphisms of the p53 gene have been associated with susceptibility to endometrial cancer. However, whether there is a specific association is still controversial. We investigated a possible association between p53 codon 72 polymorphism and endometrial cancer risk by conducting a meta-analysis. Publications addressing this association were selected from the Pubmed, Embase and CBM databases (up to January 2011). Data were extracted from the studies by two independent reviewers. The meta-analysis was performed using RevMan 5.0.25 and STATA 9.2 softwares. The odds ratio (OR) with 95% confidence intervals (CI) was calculated. Then, 10 case-control studies were retrieved, with a total of 917 endometrial cancer patients and 1680 healthy controls. Meta-analysis results showed that the Pro allele and Pro carrier (Arg/Pro + Pro/Pro) of p53 codon 72 polymorphism were significantly related with endometrial cancer risk (OR = 1.25, 95%CI = 1.10-1.41, P = 0.0005; OR = 1.34, 95%CI = 1.12-1.59, P = 0.001, respectively). In the subgroup analysis, based on ethnicity, studies were divided into Asian and Caucasian populations; the Pro allele and Pro carrier (Arg/Pro + Pro/Pro) of p53 codon 72 polymorphism were significantly related with endometrial cancer risk in Asian populations (OR = 1.41, 95%CI = 1.19-1.66, P < 0.0001; OR = 1.66, 95%CI = 1.30-2.13, P < 0.0001, respectively), but not in Caucasian populations (both P > 0.05). We concluded that the Pro allele (Arg/Pro + Pro/Pro) of p53 codon 72 polymorphism is a potential risk factor for endometrial cancer.     

The different apoptotic potential of the p53 codon 72 alleles increases with age and modulates in vivo ischaemia-induced cell death

A common arginine to proline polymorphism is harboured at codon 72 of the human p53 gene. In this investigation, we found that fibroblasts and lymphocytes isolated from arginine allele homozygote centenarians and sexagenarians (Arg+) undergo an oxidative-stress-induced apoptosis at a higher extent than cells obtained from proline allele carriers (Pro+). At variance, the difference in apoptosis susceptibility between Arg+ and Pro+ is not significant when cells from 30-year-old people are studied. Further, we found that Arg+ and Pro+ cells from centenarians differ in the constitutive levels of p53 protein and p53/MDM2 complex, as well as in the levels of oxidative stress-induced p53/Bcl-xL complex and mitochondria-localised p53. Consistently, all these differences are less evident in cells from 30-year-old people. Finally, we investigated the in vivo functional relevance of the p53 codon 72 genotype in a group of old patients (66-99 years of age) affected by acute myocardial ischaemia, a clinical condition in which in vivo cell death occurs. We found that Arg+ patients show increased levels of Troponin I and CK-MB, two serum markers that correlate with the extent of the ischaemic damage in comparison to Pro+ patients. In conclusion, these data suggest that p53 codon 72 polymorphism contributes to a genetically determined variability in apoptotic susceptibility among old people, which has a potentially relevant role in the context of an age-related pathologic condition, such as myocardial ischaemia.     

P53 codon 11, 72, and 248 gene polymorphisms in endometriosis

OBJECTIVE: Mutated p53 gene is related to the instability of cell growth and cell cycle progression. We aimed to evaluate the association between endometriosis and p53 codon 11, 72 and 248 gene polymorphisms.PATIENTS AND METHODS: Women were divided into two groups: (1) moderate/severe endometriosis (n=148), and (2) non-endometriosis groups (n=150). P53 gene polymorphisms include codon11 Glu/Gln or Lys (GAG->CAG or AAG), codon 72 Arg/Pro (CGC->CCC), and codon 248 Arg/Thr (CGG->TCG). These gene polymorphisms were amplified by polymerase chain reaction and detected by electrophoresis after restriction enzyme (Taq I, BstU I, Hap II) digestions. Associations between the endometriosis and p53 polymorphisms were evaluated.RESULTS: The distributions of p53 codon 72 polymorphisms in both groups were significantly different. The proportions of Arg homozygotes/heterozygotes/Pro homozygotes in both groups were 9.5/66.2/24.3% and 30.7/50/19.3%. The proportions of Arg/Pro alleles were 42.6/57.4% and 56/44%. The distributions of p53 codon 11 and 248 polymorphisms in both groups were non-significantly different. All individuals appeared the wild genotypes (Glu11 and Arg248 homozygotes).CONCLUSION: Association between endometriosis and p53 codon 72 polymorphism exists. P53 codon 72*Pro-related genotype and allele are related with higher susceptibility of endometriosis. P53 codon 11 and 248 polymorphisms are not related with endometriosis susceptibility.     

Polymorphisms of p53 codon 72 and MDM2 promoter 309 and the risk of endometrial cancer

Genetic polymorphisms of p53 and its negative regulator murine double minute 2 homolog (MDM2) have been shown to be closely associated with tumorigenesis in a variety of human cancers. In the present study, single nucleotide polymorphism (SNP) at p53 codon 72 and MDM2 promoter 309 was examined for germline DNA samples from 102 endometrial cancer cases and 95 controls using polymerase chain reaction-based fragment analysis. There were no significant differences in the genotype and allele prevalence between control subjects and endometrial cancer patients for p53 codon 72. The GG genotype frequency of MDM2-SNP309 was statistically higher in endometrial cancer patients than that in normal healthy women when compared with the TG genotype ( P = 0.0088). However, no statistically significant differences were found between the TT and TG or GG genotype frequencies and allele prevalence. Interestingly, the combination of the homozygous Arg/Arg genotype of p53 codon 72 and homozygous GG genotype of MDM2 SNP309 polymorphisms was significantly associated with the risk of endometrial cancer (odds ratio = 3.28, 95% confidence interval = 1.13 to 9.53, P = 0.0212). The homozygous variants of wild p53 codon 72 and mutant MDM2 promoter 309 may cooperatively increase the risk of endometrial cancer in a Japanese population.     

Cancer susceptibility polymorphism of p53 at codon 72 affects phosphorylation and degradation of p53 protein

The common polymorphism of p53 at codon 72, either encoding proline or arginine, has drawn attention as a genetic factor associated with clinical outcome or cancer risk for the last 2 decades. We now show that these two polymorphic variants differ in protein structure, especially within the N-terminal region and, as a consequence, differ in post-translational modification at the N terminus. The arginine form (p53-72R) shows significantly enhanced phosphorylation at Ser-6 and Ser-20 compared with the proline form (p53-72P). We also show diminished Mdm2-mediated degradation of p53-72R compared with p53-72P, which is at least partly brought about by higher levels of phosphorylation at Ser-20 in p53-72R. Furthermore, enhanced p21 expression in p53-72R-expressing cells, which is dependent on phosphorylation at Ser-6, was demonstrated. Differential p21 expression between the variants was also observed upon activation of TGF-β signaling. Collectively, we demonstrate a novel molecular difference and simultaneously suggest a difference in the tumor-suppressing function of the variants.     

p53 codon 72 polymorphism and Hematological Cancer Risk: An Update Meta-Analysis

Background

Previous studies on the association of p53 codon 72 (Arg72Pro) polymorphism with hematological malignancies risk have produced conflicting results. The purpose of this meta-analysis is to define the effect of p53 Arg72Pro polymorphism on hematological malignancies risk.

Methodology/Principal Findings

Through searching PubMed databases (or hand searching) up to April 2012 using the following MeSH terms and keywords: “p53”, “codon 72” “polymorphism” and “leukemia”, or “lymphoma”, or “myeloma”, thirteen were identified as eligible articles in this meta-analysis for p53 Arg72Pro polymorphism (2,731 cases and 7, 356 controls), including nine studies on leukemia (1,266 cases and 4, 474 controls), three studies on lymphoma (1,359 cases and 2,652 controls), and one study on myeloma. The overall results suggested that p53 Arg72Pro polymorphism was not associated with hematological malignancies risk. In stratified analyses, significantly increased non-Hodgkin lymphomas risk was found in p53 Arg72Pro polymorphism heterozygote model (Arg/Pro vs. Arg/Arg: OR = 1.18, 95%CI: 1.02–1.35) and dominant model (Arg/Pro+Pro/Pro vs. Arg/Arg: OR = 1.18, 95%CI: 1.03–1.34), but no significant association was found between leukemia risk and p53 Arg72Pro polymorphism. Further studies showed no association between leukemia risk and p53 Arg72Pro polymorphism when stratified in subtypes of leukemias, ethnicities and sources of controls.

Conclusions/Significance

This meta-analysis indicates that the p53 Arg72Pro polymorphism may contribute to susceptibility to non-Hodgkin lymphomas.     

Association of p53 codon 72 polymorphism with prostate cancer: a meta-analysis

Relationship of prostate cancer with the polymorphism of p53 codon 72 was reported with inconsistent results. The purpose of this study was to quantitatively evaluate the association between p53 codon 72 polymorphism and prostate cancer susceptibility. We performed an extensive search of relevant studies and made a meta-analysis, including 8 studies with 815 prostate cancer cases and 1047 controls. The combined results showed that there were no significant differences in genotype distribution between prostate cancer cases and control on the basis of all studies, CC/GC versus GG (OR = 1.24, 95% CI: 0.93–1.65), GG/GC versus CC (OR = 0.96, 95% CI: 0.60–1.55), GC versus GG (OR = 1.27, 95% CI: 0.91–1.77), CC versus GG (OR = 1.25, 95% CI:0.74–2.12), GC versus CC (OR = 1.09, 95% CI: 0.63–1.87). When stratifying for the race, there were also no statistically significant differences in genotype distribution between prostate cancer cases and controls. This meta-analysis did not provide an evidence of confirming association between p53 codon 72 polymorphism and prostate cancer.     

p53 codon 72 polymorphism and risk of cervical cancer

Storey et al. (1998) implicated the proline/argine polymorphism of the codon 72 of the tumor-suppressor gene p53 in the development of cervical cancer (CC) with the observation that the p53 protein is more efficiently inactivated by the E6 oncoprotein of human papillomavirus in p53 arginine as compared with its proline isoform. These authors further noted that in the United Kingdom, individuals homozygous for the arginine allele were several times more susceptible to HPV-associated tumorigenesis that proline/arginine heterozygotes. Subsequent studies in different countries failed to unanimously confirm this association. Motivated by the high incidence of CC in Chile, we undertook a case control study obtaining the following frequencies for genotypes PP, AP and AA in 60 ICC cases and 53 carefully selected controls: 0.067, 0.250, 0.683 and 0.075, 0.453, 0.472 respectively. A significant difference (X2 = 3.19 p < 0.02) and an odds ratio of 2.62 supported Storey et al (1998)'s results. In addition, rejecting previous hypotheses about the world distribution of the p53 codon 72 polymorphism, we conclude that this distribution most likely represents ancient human dispersal routes. Several methodological and biological explanations for the results obtained in previous negative association studies are briefly discussed.     

Influence of Arg72Pro polymorphisms of TP53 on the response of buccal cells to radiotherapy

Polymorphisms in the TP53 gene codon 72 (Arg72Pro) influence apoptosis induction and DNA damage repair. We evaluated how variants of protein p53 (p53Arg and p53Pro) affect cell death and DNA damage repair by analyzing the frequencies of karyorrhexis and micronuclei. There were significant differences in the frequency of karyorrhexis between the three p53 genotypes (Arg/Arg, Arg/Pro, and Pro/Pro), between samples taken before and after radiotherapy, and between patients and controls. The frequency of micronucleated cells increased significantly after radiotherapy. There were no significant differences in the micronucleus frequency in healthy tissues of these patients compared to controls, or in the comparisons between the three genotypes. We conclude that Arg72Pro polymorphism influences cell apoptotic capacity. This is the first study investigating karyorrhexis and micronuclei, as indicators of apoptosis after radiotherapy, and how these indicators are influenced by the TP53 polymorphism Arg72Pro.