Allelic frequency of p53 gene codon 72 polymorphism in urologic cancers

Association between TP53 gene codon72 polymorphism and prostate cancer risk: A systematic review and meta-analysis

BACKGROUND

TP53 gene polymorphism could increase risks of several kinds of cancer. But it remained controversial whether TP53 gene codon72 polymorphism was associated with the susceptibility to prostate cancer. Thus, we conducted a meta-analysis that evaluated the association between TP53 gene codon72 polymorphism and prostate cancer risk.

METHOD

A comprehensive research was performed from PubMed, Embase, Web of Science and China National Knowledge Infrastructure (CNKI) up to December 31, 2018. A random effect model was used to evaluate the effect of the outcome. The statistical analyses were performed with Review Manager 5.3.0 and Stata 14.0. The sensitivity analysis and publication bias tests were also performed to confirm the reliability of this meta-analysis.

RESULTS

22 studies included 3146 cases and 4010 controls were involved in this meta-analysis. Overall, no association was observed between TP53 gene codon72 polymorphism and prostate cancer risk (Arg vs Pro: odds ratio [OR] = 1.12, 95% confidence interval [CI] = 0.98-1.30; ArgArg vs ProPro: OR = 1.26, 95% CI = 0.90-1.75; ProPro vs ArgArg+ ArgPro: OR = 1.17, 95% CI = 0.86-1.57; ArgPro+ ProPro vs ArgArg: OR = 1.21, 95% CI = 0.97-1.51). Subgroup analyses, based on ethnicity, source of control and Hardy-Weinberg equilibrium (HWE) status, showed consistent results.

CONCLUSION

The meta-analysis we performed showed that there was no association of TP53 gene codon72 polymorphism with prostate cancer risk.

Dynamics and Molecular Mechanisms of p53 Transcriptional Activation

The "guardian of the genome", p53, functions as a tumor suppressor that responds to cell stressors such as DNA damage, hypoxia, and tumor formation by inducing cell-cycle arrest, senescence, or apoptosis. Mutation of p53 disrupts its tumor suppressor function, leading to various types of human cancers. One particular mutant, R175H, is a structural mutant that inactivates the DNA damage response pathway and acquires oncogenic functions that promotes both cancer and drug resistance. Our current work aims to understand how p53 wild-type function is disrupted due to the R175H mutation. We use a series of atomistic integrative models built previously from crystal structures of the full-length p53 tetramer bound to DNA and model the R175H mutant using in silico site-directed mutagenesis. Explicitly solvated all-atom molecular dynamics (MD) simulations on wild-type and the R175H mutant p53 reveal insights into how wild-type p53 searches and recognizes DNA, and how this mechanism is disrupted as a result of the R175H mutation. Specifically, our work reveals the optimal quaternary DNA binding mode of the DNA binding domain and shows how this binding mode is altered via symmetry loss as a result of the R175H mutation, indicating a recognition mechanism that is reminiscent of the asymmetry seen in wild type p53 binding to nonspecific genomic elements. Altogether our work sheds new light into the hitherto unseen molecular mechanisms governing transcription factor, DNA recognition.

TP53 codon 72 Polymorphism and bladder cancer risk: a meta-analysis and emphasis on the role of tumor or smoking status

Background: Various studies had explored the relationship between TP53 codon 72 polymorphisms and the risk of bladder cancer (BC). However, their results remained inconsistent and the definite role of smoking or tumor status associated with this polymorphism in BC cases was seldom involved. Hence, this meta-analysis was to disclose such associations. Methods: Systematical and comprehensive retrieval of online databases PubMed, PMC, EMBASE and Web of Science were conducted to obtain eligible studies, up to May 30th, 2018. Pooled odds ratios (ORs) with 95% confidence intervals (CI) were utilized to assess the associations between TP53 codon 72 polymorphisms and BC susceptibilities under five genetic comparison models. Results: Ultimately, this meta-analysis enrolled 22 applicable studies with 3,791 BC cases and 4,917 controls. Our results suggested that the variant genotypes were associated with BC risk in Asian subgroup (allele model: OR=1.19, 95% CI=1.04-1.34; dominant model: OR=1.27, 95% CI=1.06-1.52; homozygote model: OR=1.36, 95% CI=1.03-1.80), while negative outcomes were presented in Caucasians. In the relationship between TP53 codon 72 polymorphisms and BC tumor stage in Asian group, positive results were presented in allele model: OR=1.68, 95% CI=1.04-2.72; dominant model: OR=2.46, 95% CI=1.08-5.61; heterozygous model: OR=2.32, 95% CI=1.04-5.14; homozygote model: OR=2.66, 95% CI=1.04-6.81. However, no evidence was revealed between this polymorphism and BC tumor grade. Besides, significant associations were displayed between TP53 codon 72 polymorphism and smoking status (allele model: OR=1.40, 95% CI=1.06-1.84; dominant model OR=1.72, 95% CI=1.18-2.50; heterozygous model: OR=1.77, 95% CI=1.19-2.64). Conclusion: Taken together, our results shed light on that TP53 codon 72 polymorphism was significantly associated with the susceptibility to BC in Asians. In addition, positive associations were also revealed between this polymorphism and tumor stage/smoking status in BC cases.

TP53 Arg72Pro polymorphism is associated with increased overall survival but not response to therapy in Portuguese/Caucasian patients with advanced cervical cancer

Identification of mechanisms that influence the therapeutic response and survival in patients with cancer is important. It is known that the genetic variability of the host, including presence of genetic polymorphisms in genes involved in DNA damage response, serves a crucial role in the prognosis of these patients. The present hospital-based retrospective cohort study aimed to evaluate the influence of TP53 Arg72Pro (rs1042522) polymorphism in the clinical outcome of 260 Caucasian patients diagnosed with cervical cancer and treated with concomitant radiotherapy and chemotherapy. The polymorphism genotyping was assessed using allelic discrimination by quantiative polymerase chain reaction. The results indicate that the TP53 Arg72Pro polymorphism did not significantly impact the response to therapy (P=0.571) nor disease-free survival (P=0.081). However, the polymorphism did influence overall survival, as increased median survival time was observed for patients carrying Arg/Pro genotype when compared with patients with Arg/Arg and Pro/Pro genotypes (126 months vs. 111 months, respectively; P=0.047). To conclude, the present findings suggest that a pharmacogenomic profile based on the genetic background of patients, including the analysis of the TP53 genotypes, may individualize treatment nad assist in the selection of therapies that may improve clinical outcome and lower toxicity for the patients.

Polymorphism at Codon 72 of the p53 Gene Is Not associated With Endometriosis in a Japanese Population

OBJECTIVE

Endometriosis is inherited as a complex trait, which means that multiple susceptibility genes interact with each other and the environment to produce the phenotype. Previous studies have implicated p53, a tumor suppressor gene, as a factor in the development of the disease. In a Japanese population, we investigated the frequency of the p53 polymorphism in women affected with endometriosis.

METHODS

We compared the distribution of the p53 codon 72 polymorphism in endometriosis cases (n = 111) and population controls consisting of female neonates (n = 180) by using polymerase chain reaction restriction fragment-length polymorphism analysis in a Japanese population.

RESULTS

The frequencies of the three p53 genotypes, Arginine (Arg)/Arg, Arg/Proline (Pro), and Pro/Pro in controls were 39.4%, 41.7%, and 18.9 %, respectively. The crude genotype frequencies in the endometriosis cases were similar to those of the controls (35.2%, 48.6%, and 16.2%, respectively). Using the Arg/Arg genotype as the reference, the odds ratios of the Arg/Pro and Pro/Pro genotypes were 1.30 (95% confidence interval [CI] 0.72-1.86, P =.33) and 0.96 (95% CI 0.47-1.94, P =.91), respectively. Thus, there were no significant differences in the frequency of the p53 codon 72 polymorphism between endometriosis cases and controls in this population. The endometriosis cases with severe disease only were also evaluated, but no significant difference was observed in the frequency of the polymorphism between this subgroup and the controls.

CONCLUSION

Our findings suggest that the p53 codon 72 polymorphism is unlikely to be associated with endometriosis in Japanese women.

No association of TP53 codon 72 SNP with male infertility: a study in a Chinese population and a meta-analysis

Genetic polymorphisms may affect human male fertility. Even though TP53 plays a role in spermatogenesis we know little about the association of the functional polymorphism at codon 72 of TP53 with respect to susceptibility to male infertility. We conducted a case-control study to investigate this association in a Chinese population and performed a meta-analysis in different populations to clarify this association. The single nucleotide polymorphism (SNP) of TP53 codon 72 (rs1042522 G>C) was genotyped by PCR-RFLP in 83 Chinese male infertility patients and 401 healthy controls. Meta-analysis was performed using the data from four currently available studies. The data from our study were overlayed using the v.9.0 STATA software package. We observed no association between the TP53 codon 72 polymorphism and male infertility (p = 0.84, OR = 1.04, 95% CI, 0.74-1.45). Meta-analysis confirmed the case-control result that there was no significant association between the codon 72 polymorphism of TP53 and male infertility (Pro vs. Arg; p = 0.31, OR = 0.86, 95% CI, 0.65-1.15; Pro/Pro vs. Arg-carriers; p = 0.65, OR = 0.91, 95% CI, 0.61-1.36; Pro-carriers vs. Arg/Arg: p = 0.15, OR = 0.75, 95% CI, 0.51-1.11). The data presented in this communication supports the view that the codon 72 polymorphism of TP53 may not contribute to male infertility susceptibility in the Chinese population.

Impact of TP53 codon 72 and MDM2 SNP 309 polymorphisms in pancreatic ductal adenocarcinoma

Single-nucleotide polymorphisms (SNPs) of TP53 (codon 72, rs1042522) and MDM2 promoter (SNP 309, rs2279744) have been associated with risk for various human cancers. However, studies analyzing these polymorphisms in pancreatic ductal adenocarcinoma (PDAC) are lacking. We investigated TP53 codon 72 and MDM2 SNP 309 polymorphisms in 32 patients with PDAC, 16 patients with chronic pancreatitis (CP), and 32 normal controls, using formalin-fixed paraffin-embedded tissue. We also examined TP53 and MDM2 protein immunohistochemistry (IHC) to assess the involvement of these differences in malignant transformation and disease progression. TP53 Pro/Pro genotype was significantly more frequent in PDAC patients than in controls (65.6 vs. 15.6%, p < 0.001) and no significant difference was found between CP patients (37.5%) and controls. In MDM2 SNP 309, there were no significant differences among the three groups. Based on the Kaplan-Meier analysis, overall survival was significantly shorter in MDM2 G/G genotypes compared with other genotypes (G/T and T/T) (359 vs. 911 days, p = 0.016) whereas no significant differences in TP53 genotypes were observed (638 vs. 752 days, p = 0.471). Although TP53 IHC was frequent in PDAC patients (53.1%), TP53 and MDM2 protein expression was not correlated with polymorphisms. Our study demonstrated TP53 codon 72 polymorphism is potentially a genetic predisposing factor while MDM2 SNP 309 polymorphism might be useful in predicting survival outcome.

Detection of human papillomavirus (HPV) DNA prevalence and p53 codon 72 (Arg72Pro) polymorphism in prostate cancer in a Greek group of patients

Prostate cancer is the most common neoplasm found in males and the second most frequent cause of cancer-related mortality in males in Greece. Among other pathogens, the detection frequency of human papillomavirus (HPV) has been found to be significantly increased in tumor tissues among patients with sexually transmitted diseases (STDs), depending on the geographical distribution of each population studied. The present study focused on the detection of HPV and the distribution of Arg72Pro p53 polymorphism in a cohort of healthy individuals, as well as prostate cancer patients. We investigated the presence of HPV in 50 paraffin-embedded prostate cancer tissues, as well as in 30 physiological tissue samples from healthy individuals by real-time PCR. Furthermore, the same group of patients was also screened for the presence of the Arg72Pro polymorphism of the p53 gene, a p53 polymorphism related to HPV. Out of the 30 control samples, only 1 was found positive for HPV (3.33 %). On the contrary, HPV DNA was detected in 8 out of the total 50 samples (16 %) in the prostate cancer samples. The distribution of the three genotypes, Arg/Arg, Arg/Pro, and Pro/Pro, was 69.6, 21.7, and 8.7 % in the cancer patients and 75.0, 17.86, and 7.14 % in healthy controls, respectively. No statistically significant association was observed between the HPV presence and the age, stage, p53 polymorphism status at codon 72, or PSA. The increased prevalence of HPV detected in the prostate cancer tissues is in agreement with that reported in previous studies, further supporting the association of HPV infection and prostate cancer.

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

Many studies have been conducted to explore the association between p53 codon 72 polymorphism and prostate cancer (PCa). However, the results remain inconsistent. Therefore, we performed a large meta-analysis of relevant studies to determine a more precise estimation of this relationship. Systematic searches of the electronic databases PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure (CNKI) up to October 2013 were performed. Fixed or random-effects meta-analytical models were used to calculate the summary odds ratio (OR) and corresponding 95% confidence intervals (CIs). Meta-regression, Galbraith plots, subgroup analysis, and sensitivity analysis were also performed. The study included 17 case-control studies involving 2,371 PCa cases and 2,854 controls. Our results showed that the p53 codon 72 polymorphism was not associated with PCa risk in all genetic models in the overall populations. When limiting the meta-analysis to the studies conforming to Hardy-Weinberg equilibrium, the pooled analyses showed a significant association between p53 codon 72 polymorphism and PCa in a Caucasian population in co-dominant model Pro/Pro vs. Arg/Arg (OR = 1.57, 95% CI = 1.08-2.28, P = 0.017) and recessive model Pro/Pro vs. (Arg/Pro + Arg/Arg) (OR = 1.60, 95% CI = 1.12-2.27, P = 0.009). In subgroup analysis stratified by PCa stages and Gleason grades, a slight but significant association was found when advanced PCa was compared with localized PCa only in recessive model Pro/Pro vs. (Arg/Pro + Arg/Arg) (OR = 1.51, 95% CI = 1.02-2.23, P = 0.039). This meta-analysis suggested that the Pro/Pro genotype of p53 codon 72 polymorphism was associated with increased prostate cancer risk, especially among Caucasians.

Association between p53 Pro72Arg polymorphism and prostate cancer risk: a meta-analysis

The tumor suppressor gene p53 appears to be important in the development of many human cancers, such as prostate cancer. The association of p53 codon72 polymorphism with prostate cancer has been widely reported; however, the results are inconsistent. To derive a more precise estimation of this relationship, we performed an updated meta-analysis from 10 case-control studies. We conducted a search in the PubMed database without a language limitation, covering all papers published until July 2010. Risk ratios (RR) with 95% confidence intervals(CIs) were used to assess the strength of the association. Ten studies including 1,196 cases and 1,704 controls were selected. Overall, no significant differences of total prostate cancer risk and p53 codon polymorphism was found (Pro/Pro vs Arg/Arg, RR = 1.12, 95%CI=0.74-1.70, P_{heterogeneity} = 0.016, I² = 55.8%; Pro/Pro+Pro/Arg vs Arg/Arg, RR = 1.05, 95%CI=1.00-1.11, P_{heterogeneity} = 0.077, I² = 51.1%). In the stratified analysis by ethnicity, the same results were found. However, in the control subgroup, there was a modest decreased association between prostate cancer risk and population-based control subjects under the recessive genetic model (RR = 0.31, 95%CI=0.10-0.91, P_{heterogeneity} = 0.110, I² =60.8%). This meta-analysis suggested that p53 codon Pro72Arg polymorphism could be weakly associated with prostate cancer risk.

Quantitative assessment of the association between TP53 Arg72Pro polymorphism and bladder cancer risk

Previous studies investigating the association between TP53 Arg72Pro polymorphism and bladder cancer risk reported controversial results. To quantify the strength of association between TP53 Arg72Pro polymorphism and bladder cancer risk, we performed this meta-analysis. We searched PubMed, Embase and Wangfang databases for studies relating the association between TP53 Arg72Pro polymorphism and bladder cancer risk. We used the pooled odds ratios (ORs) with their 95 % confidence intervals (95 % CIs) to assess the association. Finally, data were available from a total of 16 case-control studies including a total of 5, 545 subjects (2,345 cases and 3,200 controls). Meta-analysis of all 16 studies showed TP53 Arg72Pro polymorphism was not associated with bladder cancer risk (All P values were more than 0.10). Subgroup analyses by ethnicity showed that TP53 Arg72Pro polymorphism contributed to bladder cancer risk in East Asians in three genetic models (For Pro vs. Arg, Fixed-effects OR 1.18, 95 % CI 1.05-1.32; For ProPro vs. ArgArg, Fixed-effects OR 1.40, 95 % CI 1.11-1.77; For ProPro vs. ArgPro/ArgArg, Fixed-effects OR 1.32, 95 % CI 1.07-1.62). However, there was no significant association in Caucasians and the others (All P values were more than 0.05). Heterogeneity analyses suggested ethnicity was the major sources of heterogeneity. Thus, meta-analyses of available data suggest the Pro variant of TP53 Arg72Pro contributes to bladder cancer risk in East Asians. Besides, TP53 Arg72Pro polymorphism may have race-specific effects on bladder cancer risk and further studies are needed to elucidate this possible effect.

Association of p53 Arg72Pro polymorphism with bladder cancer: a meta-analysis

BACKGROUND

p53 tumor suppressor gene Arg72Pro polymorphism has been associated with bladder cancer. However, results were inconsistent. We performed this meta-analysis to estimate the association between p53 Arg72Pro polymorphism and bladder cancer.

METHODS

Electronic search of PubMed was conducted to select studies. Studies containing available genotype frequencies of Arg72Pro were chosen, and pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association.

RESULTS

The final meta-analysis included 14 published studies with 2176 bladder cancer cases and 2798 controls. The results suggested that the variant genotype was associated with the bladder cancer risk (additive model: OR=1.72, 95% CI: 1.036-1.325, P=0.011; dominant model: OR=1.268, 95% CI: 1.003-1.602, P=0.047) in Asian subgroup. However, the association was not significant between this polymorphism and bladder cancer risk in Caucasian (additive model: OR=0.773, 95% CI: 0.564-1.059, P=0.109; dominant model: OR=0.685, 95% CI: 0.418-1.124, P=0.134).

CONCLUSION

This meta-analysis suggests that p53 Arg72Pro polymorphism is associated with increased risk of bladder cancer in Asians. To validate the association between this polymorphism and bladder cancer, further studies with larger participants worldwide are needed.

Implication of DNA repair genes in prostate tumourigenesis in Indian males

BACKGROUND & OBJECTIVES

Prostate cancer (CaP) is the fifth most common cancer among Indian men. Tumour protein p53 (TP53) gene increases the fidelity of DNA replication and homologous recombination by transcriptional transactivation of mismatch repair (MMR) genes. DNA repair thus has a potential role in molecular carcinogenesis of CaP. The aim of the present study was to identify mutations, and polymorphisms in TP53 gene and MMR protein expression in CaP in Indian male population.

METHODS

TP53 codon 72 polymorphism was analysed in 105 CaP, 120 benign prostatic hyperplasia (BPH) cases and 106 normal controls. Mutational analysis of TP53 was done in DNA extracted from formalin fixed paraffin embedded tissue of 80 CaP and 24 BPH cases. Expression of MMR proteins viz. hMLH1, hMSH2, hPMS1 and hPMS2 was studied in 80 CaP, 15 prostatic intraepithelial neoplasia (PIN) and 15 BPH cases.

RESULTS

A somatic C/A variation at the intronic boundary of exon 7 in TP53 gene was observed in one each biopsy samples from CaP and BPH. A significant association of codon 72 TP53 Pro/Pro genotype was observed with the risk of CaP (OR, 2.59, P=0.02) and BPH (OR, 6.27, P<0.001). Immunohistochemical analysis of MMR proteins showed maximum loss of hPMS1 expression in cases of CaP and PIN while no loss in expression of MMR proteins was observed in BPH cases. The study also identified a significant loss of hPMS2 protein in poorly differentiated tumours (Gleason score >7) than in well differentiated tumours (Gleason score 3-6) (P<0.05).

INTERPRETATION & CONCLUSIONS

The results of the present study demonstrate that TP53 codon 72 polymorphism plays significant role in the pathogenesis and susceptibility to CaP and BPH. Also, an aberrant MMR protein expression could be involved in progression of prostate cancer through PIN, early CaP to aggressive CaP. The loss of hPMS2 protein expression may serve as a marker for progression of CaP.

Polymorphisms in promoter sequences of MDM2, p53, and p16 genes in normal Japanese individuals

Research has been conducted to identify sequence polymorphisms of gene promoter regions in patients and control subjects, including normal individuals, and to determine the influence of these polymorphisms on transcriptional regulation in cells that express wild-type or mutant p53. In this study we isolated genomic DNA from whole blood of healthy Japanese individuals and sequenced the promoter regions of the MDM2, p53, and p16(INK4a) genes. We identified polymorphisms comprising 3 nucleotide substitutions at exon 1 and intron 1 regions of the MDM2 gene and 1 nucleotide insertion at a poly(C) nucleotide position in the p53 gene. The Japanese individuals also exhibited p16(INK4a) polymorphisms at several positions, including position -191. Reporter gene analysis by using luciferase revealed that the polymorphisms of MDM2, p53, and p16(INK4a) differentially altered luciferase activities in several cell lines, including the Colo320DM, U251, and T98G cell lines expressing mutant p53. Our results indicate that the promoter sequences of these genes differ among normal Japanese individuals and that polymorphisms can alter gene transcription activity.

Dancing on DNA: kinetic aspects of search processes on DNA

Recognition and binding of specific sites on DNA by proteins is central for many cellular functions such as transcription, replication, and recombination. In the search for its target site, the DNA-associated protein is facing both thermodynamic and kinetic difficulties. The thermodynamic challenge lies in recognizing and tightly binding a cognate (specific) site among the billions of other (non-specific) sequences on the DNA. The kinetic difficulty lies in finding a cognate site in mere seconds amidst the crowded cellular environment that is filled with other DNA sequences and proteins. Herein, we discuss the history of the DNA search problem, the theoretical background and the various experimental methods used to study the kinetics of proteins searching for target sites on DNA.

A single-molecule characterization of p53 search on DNA

The tumor suppressor p53 slides along DNA while searching for its cognate site. Central to this process is the basic C-terminal domain, whose regulatory role and its coordination with the core DNA-binding domain is highly debated. Here we use single-molecule techniques to characterize the search process and disentangle the roles played by these two DNA-binding domains in the search process. We demonstrate that the C-terminal domain is capable of rapid translocation, while the core domain is unable to slide and instead hops along DNA. These findings are integrated into a model, in which the C-terminal domain mediates fast sliding of p53, while the core domain samples DNA by frequent dissociation and reassociation, allowing for rapid scanning of long DNA regions. The model further proposes how modifications of the C-terminal domain can activate "latent" p53 and reconciles seemingly contradictory data on the action of different domains and their coordination.

p53 Pro72Arg polymorphism and prostate cancer in men of African descent

BACKGROUND

p53 is a transcription factor that regulates the cell cycle, DNA repair, and apoptosis. A variant at codon 72, rs1042522, results in altered activities for p53 and is, notably, differentially distributed among different ethnic populations. However, associations of this variant with cancer in men of African descent have not been explored. Herein, we tested the hypothesis that rs1042522 was associated with prostate cancer (PCa) risk.

MATERIALS AND METHODS

Genotypes were determined by PCR-RFLP methods in a study population of African descent consisting of 266 PCa patients and 196 male controls.

RESULTS

Our results indicate that the p53 polymorphism may be associated with increased risk of PCa. Genotypes were significantly and marginally associated with PCa risk using the dominant and log-additive genetic models (OR=1.53, 95% CI: 1.02-2.29, P=0.04; OR=1.33, 95% CI: 0.99-1.78, P=0.06, respectively). After adjusting for age, the associations with PCa remained, but results were not statistically significant (OR=1.48, 95% CI: 0.95-2.31, P=0.08; OR=1.30, 95% CI: 0.95-1.80, P=0.10, respectively).

CONCLUSIONS

The present study demonstrates that population-dependent differences in allele frequencies associated with health disparities provide a valuable framework for the interrogation of complex diseases in all populations.

Association between polymorphisms of TP53 and MDM2 and prostate cancer risk in southern Chinese

Alterations in the TP53 and MDM2 genes appear to be important in the development of many human tumors, but evidence is conflicting on associations between polymorphisms in these genes and risk of prostate cancer (PCa). The influence of TP53 codon 72, MDM2 SNP309, and MDM2 C1797G polymorphisms in southern Chinese PCa patients was investigated. In the comparison of genotype distributions of TP53 codon 72 between cases and controls, the adjusted odds ratios for PCa associated with the Pro/Pro, Arg/Pro, and Arg/Arg genotypes were 1.00, 1.89 (95% CI = 1.20-2.97), and 2.01 (95% CI = 1.11-3.64), respectively; however, MDM2 SNP309 and C1797G did not show any significant difference between cases and controls. When TP53 and MDM2 polymorphisms were combined based on the numbers of variant risk alleles (i.e., G-allele of TP53 codon 72, G-allele of MDM2 SNP309, and G-allele of MDM2 C1797G), individuals with 3-5 variants had a 1.56-fold greater risk of PCa than those with 0-2 variants (95% CI = 1.07-2.26). Moreover, subjects with 0-2 variants had 33.3% positive p53 expression, whereas subjects with 3-5 variants had 23.3% p53 expression (P = 0.39). These findings suggest that TP53 and MDM2 polymorphisms play a role in PCa susceptibility in southern Chinese Han population.

Polymorphisms in promoter sequences of the p15 ( INK4B ) and PTEN genes of normal Japanese individuals

Gene promoter regions of p15(INK4B), a cyclin-dependent kinase inhibitor, and phosphatase and tensin homolog (PTEN), a dual-function protein and lipid phosphatase, interact with regulatory factors for gene transcription and methylation. Normal individuals exhibit sequence polymorphisms in these regulatory genes. We isolated genomic DNA from whole blood of healthy Japanese individuals and sequenced promoter regions of the p15 ( INK4B ) and PTEN genes. We also examined the influence of polymorphisms on promoter activity in several cell lines. We identified polymorphisms at positions -699, -394, and -242 and an insertion at position -320 in the p15 ( INK4B ) gene and a polymorphism at position -1142 in the PTEN gene. Reporter gene analysis revealed that these polymorphisms influenced transcriptional regulation in their cell lines. Our results indicate for the first time that promoter sequences of the p15 ( INK4B ) and PTEN genes differ among normal Japanese individuals and that promoter polymorphisms can influence gene transcription.

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.

Meta-analysis of association between TP53 Arg72Pro polymorphism and bladder cancer risk

OBJECTIVES

To perform a meta-analysis to explore a more robust estimate of the effect of the TP53 Arg72Pro polymorphism on bladder cancer risk. Studies investigating the association between TP53 Arg72Pro polymorphism and bladder cancer risk have reported conflicting results.

METHODS

All eligible studies were searched in PubMed. The quality of the studies was evaluated according to a predefined scale. Crude odds ratios, with the 95% confidence intervals, were assessed for the association using fixed- and random-effects models.

RESULTS

We identified 10 case-control studies involving 3549 subjects for the present meta-analysis. Overall, no evidence of an association was observed between the TP53 genotypes and bladder cancer susceptibility when all the studies were pooled into the meta-analysis. However, a significantly decreased risk of bladder cancer was associated with TP53 genotypes for Arg/Arg versus Pro/Pro (odds ratio 0.74, 95% confidence interval 0.55-0.99) and Arg/Arg plus Arg/Pro versus Pro/Pro (odds ratio 0.77, 95% confidence interval 0.59-1.00) in Asians. In contrast, no effect of this polymorphism on bladder cancer in whites, Africans, or other population was observed when only high-quality scored studies were considered.

CONCLUSIONS

The results of the present meta-analysis suggest that the TP53 Arg72 allele is a protective factor and that the Pro/Pro genotype might increase the susceptibility to bladder cancer in Asians. The conflicting findings among studies might have resulted from variations in the allele frequencies among the different races, as well as the methodologic quality of the studies.

Polymorphisms of TP53 codon 72 with prostate carcinoma risk: a meta-analysis

Previous published data indicated TP53 codon 72 polymorphisms as risk factors for various cancers. A large number of studies have been conducted on the association of TP53 codon 72 polymorphisms with susceptibility to prostate carcinoma and have yielded inconclusive results. The aim of the present study is to derive a more precise estimation of the relationship. We conducted a search in the Medline, EMBASE, OVID, Sciencedirect, and Chinese National Knowledge Infrastructure (CNKI) without a language limitation, covering all papers published up to Feb 2009. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications. A total of six case-control studies, including 582 cases and 1075 controls, met the included criteria and thus were selected. Consequently, the relevant data were extracted and further analyzed using systematic meta-analyses. For the overall data, no associations of TP53 codon 72 polymorphisms with prostate carcinoma were observed (for Arg/Arg versus Pro/Pro: OR = 0.88; 95%CI = 0.62-1.25; for dominant model: OR = 1.05; 95%CI = 0.78-1.43; for recessive model: OR = 0.85; 95%CI = 0.67-1.06). In the subgroup analysis by ethnicity, individuals carrying Arg allele may have an increased susceptibility to prostate cancer compared with those carrying Pro allele in Caucasians. While for Asians, TP53 codon 72 polymorphism was unlikely to be a risk factor for prostate cancer. Moreover, TP53 codon 72 polymorphism seems to exert little effect on the metastasis and differentiation status of developing prostate carcinoma. Collectively, the results of the present study suggest that TP53 codon 72 polymorphism might be a low-penetrant risk factor for developing prostate carcinoma in Caucasians but not in Asians.

TP53 codon 72 Gene Polymorphism Paradox in Associated with Various Carcinoma Incidences, Invasiveness and Chemotherapy Responses

TP53 is the most common mutated gene in human cancers. Approximately half of all human malignancies exhibit TP53 mutations. The TP53 codon 72 polymorphism is a single-nucleotide polymorphism (SNP) in exon 4, resulting in the expression of either arginine (CGC) or proline (CCC) residues. In this article, we review literatures published in MEDLINE, and attempt to describe how these two polymorphic variants of TP53 are functionally distinct, and how they influence cancer vulnerability and response to chemotherapy. The Arg72 variant has been shown to be more likely to induce apoptosis than the Pro72 variant, due to its ability to localize itself to mitochondria and trigger the release of cytochrome c into the cytosol. However, the influence of the TP53 codon 72 polymorphism on the risk of developing various cancers, and their progression remains inconclusive because there has been no sustained evidence supporting a crucial role for the codon 72 variant in cancer therapy till now. We hypothesize that TP53 gene might not only be involved in cell cycle control and the apoptosis induction response to DNA damage, but may also modulate individual cancer risk, and that this may correlate with the biofunctions of the two codon 72 variants. Additionally, latent factors might function synergistically with codon 72 variants to confer susceptibility to cancer development, progression, prognosis, and therapeutic responsiveness. Further etiological investigations are essential to reveal the association of and interaction between genetic and environmental factors in relation to carcinogenesis.

Lack of association between polymorphisms in p53 gene and spermatogenetic failure in a Chinese population

Although various genetic factors have been demonstrated in human male infertility, many genetic causes involving gene variants for the idiopathic male infertility have not yet been elucidated. P53 gene is involved in the meiosis of the male rat and mice, which suggested that p53 plays a critical role in spermatogenesis. To examine whether the codon72 polymorphism and IVS7+72C>T polymorphism of the human p53 gene are associated with spermatogenetic failure in Han-Chinese population. A case-control study was conducted with 198 idiopathic infertile patients with nonobstructive azoospermia or severe oligozoospermia and 233 fertile controls. We genotyped the two polymorphisms, codon72 and IVS7+72C>T, using polymerase chain reaction-restriction fragment length polymorphism assay. The polymorphisms were identified in both infertile patients and fertile controls. The allele and genotype frequencies of the two polymorphisms were not significantly different between the patients and controls. Further analysis showed that there was no statistically significant difference in the haplotype distributions between the patients and controls. The results of this study suggest that the codon72 and IVS7+72C>T polymorphisms of the p53 gene are unlikely to contribute to the pathogenesis of idiopathic male infertility with spermatogenetic failure.

Role of glutathione-S-transferase and codon 72 of P53 genotypes in epithelial ovarian cancer patients

PURPOSE

A series of polymorphisms in germ-line DNA have been investigated in an effort to delineate polygenic models of cancer susceptibility and prognosis. As low-penetrance susceptibility genes may combine additively or multiplicatively and contribute to cancer incidence and to the response to chemotherapy, we studied GSTT1, GSTM1, GSTO2, GSTP1 and codon 72 of p53 genotype profiles in ovarian cancer patients.

METHODS

We compared 69 ovarian cancer patients with 222 control healthy women paired for ethnic and life-style characteristics. Outcome was evaluated in 29 stage III and IV patients submitted to a platinum-based chemotherapy followed-up for 6-29 months (17 +/- 9 months).

RESULTS

GSTT1, GSTM1, GSTO2 and GSTP1 genes presented a similar genotype distribution, but codon 72 of p53 gene wild-type variant was less frequent in ovarian cancer patients than in controls (chi(2); P = 0.0004).

CONCLUSIONS

We were unable to demonstrate any association between the GST genotypes studied and the risk of ovarian cancer but the inheritance of a heterozygous Arg/Pro genotype of p53 increased the risk of ovarian cancer more than 2.5 times (OR = 2.571; 95% CI = 1.453-4.550). There was no association of the studied genes to any clinical or pathological feature of the patients or to their response to chemotherapy.

p53 Codon 72 and p21 Codon 31 Polymorphisms in Prostate Cancer

The tumor suppressor gene p53 and its downstream effector p21 are thought to play major roles in the development of human malignancy. Polymorphic variants of p53 at codon 72, and p21 at codon 31, have been found to be associated with cancer susceptibility, but few studies have investigated their effect on prostate cancer risk. In this case-control study, we investigated the association of p53 codon 72 and p21 codon 31 polymorphisms with prostate cancer risk in a Taiwanese population. In total, 200 patients with prostate cancer, 247 age-matched male controls, and 181 non–age-matched symptomatic benign prostatic hyperplasia (BPH; American Urological Association symptom score ≥ 8 and prostate volume &gt; 20 gm) recruited from two medical centers in southern Taiwan were genotyped. Overall, we found no significant association between p53 polymorphism and risk of prostate cancer. However, for p21 polymorphism, the frequencies of p21 Ser/Ser, Ser/Arg and Arg/Arg were 52 (26.0%), 85 (42.5%), 63 (31.5%) in case patients, 48 (26.5%), 82 (45.3%), 51 (28.2%) in BPH patients, and 76 (30.8%), 119 (48.2%), 52 (21.1%) in controls, respectively. Among the prostate cancer cases and controls, subjects with Arg/Arg genotype were found to have a 1.78-fold increased risk [95% confidence interval (CI), 1.06-3.01] of developing prostate cancer compared with those having the Ser/Ser genotype, after adjusting for other potential covariates. This significant association was slightly stronger [odds ratio (OR), 2.13; 95% CI, 1.16-3.92] in younger men (≤ 72 years; n = 99 and 126 for cases and controls, respectively) and correlated with localized disease stage (OR, 1.96; 95 % CI, 1.15-3.35) and moderately differentiated prostate cancer (OR, 2.04; 95% CI, 1.17-3.53). In addition, the Arg/Arg genotype was associated with BPH risk in those with large prostate volumes (&gt; 50 mL) compared with those having the Ser/Ser genotype [OR, 2.29; 95% CI, 1.07-4.98]. Our findings suggest that the p21 codon 31 polymorphism may be associated with the development of prostate enlargement and cancer.

Proline homozygosity in codon 72 of p53 is a factor of susceptibility for thyroid cancer

A common germline polymorphism of p53 gene produces an Arginine to Proline change at aminoacid position 72. The resulting codon 72 variants have been reported associated with tumor susceptibility since they reduce p53 ability to activate apoptosis. Codon 72 polymorphism may play a role in subside vulnerability to different carcinogens and might account for ethnic variations in cancer frequency. Using an allele-specific polymerase chain reaction (PCR), we tested peripheral blood samples from 98 patients with thyroid cancer, including 21 follicular (FC) and 77 papillary carcinomas (PC), 44 patients with benign nodules, including 14 follicular adenomas and 30 goiters and 153 healthy individuals from the same geographical region. Data on lifetime occupational history, smoking history, general health conditions, previous diseases and other anamnestic data were obtained through interviews. Patients with FC (Pro/Pro = 19.0%, Arg/Arg = 42.9%, Arg/Pro = 38%) and with PC (Pro/Pro = 10.3%, Arg/Arg = 36.36%, Arg/Pro = 53.24%) showed a significant overrepresentation of codon 72 variants compared to the control population (Pro/Pro = 1.9%, Arg/Arg = 33.3%, Arg/Pro = 64.7%) (P = 0.0015). The Pro/Pro genotype, after adjusting for gender, age, tobacco and drugs, was associated with a markedly higher risk of FC (OR=9.714; CI: 2.334-40.436) and of PC (OR=5.299; CI: 2.334-40.436). These results provide evidence that p53 polymorphism is implicated in thyroid carcinogenesis and that individuals harboring the Pro/Pro genotype have an increased risk of developing thyroid cancer.

Polymorphisms of estrogen receptor alpha in prostate cancer

Estrogen receptor (ER) alpha polymorphisms have been shown to be involved in the oncogenesis of several organs. We hypothesize that polymorphisms of the ERalpha gene are risk factors for prostate cancer. The genotypic distributions of six different loci (codons: 10 T-->C, 87 G-->C, 243 C-->T, 325 C-->G, 594 G-->A, and intron 1 C-->T) of the ERalpha gene were analyzed in prostate cancer tissues. The DNA from 115 cases of prostate cancer (Japanese population) was analyzed by sequence-specific polymerase chain reaction (PCR) and direct sequencing to determine the genotypic and allelic frequencies of the six different polymorphic loci of ERalpha. The relative risk of variant genotype was calculated by comparison with 200 healthy controls. Results of this study showed that the frequency of the variant genotype (C/C) on codon 10 was significantly higher in prostate cancer patients. The odds ratio (OR) was calculated as 3.26 compared to wild-type (T/T) with a 95% confidence interval (CI) of 1.58-6.73. Allele frequency at codon 10 also differed between groups. No association was found between codon 10 polymorphism and the stage of cancer. Polymorphism was not observed in codon 87, and frequencies of genotypes and alleles at other loci (intron 1, codons 243, 325, and 594) were not statistically different between cancer and controls. The present study suggests that polymorphism in codon 10 of ERalpha may be a risk factor for prostate cancer. These results are important in understanding the role of ERalpha polymorphism in the pathogenesis of prostate cancer.

A p53 codon 72 polymorphism associated with prostate cancer development and progression in Japanese

An association between the Pro/Pro genotype of p53 codon 72 and a lower risk of prostate cancer in Caucasians was recently reported. However, the association of this polymorphism with prostate cancer risk in a Japanese population has not been clarified. We performed a case-control study consisting of 114 prostate cancer patients and 105 noncancer controls. Sixty-nine percent (79 of 114) of the patients had a positive family history. The genotypic frequencies in the controls were 39.0% for Arg/Arg, 54.3% for Arg/Pro and 6.7% for Pro/Pro; they were in Hardy-Weinberg equilibrium. When a comparison of the distribution of the p53 codon 72 polymorphism was made between patients with a first-degree family history and all control subjects, the adjusted odds ratios (ORs) for prostate cancer associated with the Arg/Arg, Arg/Pro and Pro/Pro genotypes were 1.00, 0.99 [95% confidence interval (CI) 0.53-1.88] and 2.80 (95% CI 1.04-7.53), respectively. When stratification of cases was performed based on clinical stage (localized or metastatic cancer) and pathological grade (a Gleason score of <7 or > or =7), there tended to be a greater number of patients with localized cancers among those patients with the Arg/Pro genotype than among those with the Arg/Arg genotype (overall cases: age-adjusted OR 0.36, 95% CI 0.13-1.00, p = 0.049; positive family history cases: age-adjusted OR 0.25, 95% CI 0.075-0.84, p = 0.025). In addition, there tended to be a greater number of patients with low-grade cancers among those with the Pro/Pro genotype than among those with other genotypes (overall cases: age-adjusted OR 0.41, 95% CI 0.13-1.30, p = 0.13; positive family history cases: age-adjusted OR 0.20, 95% CI 0.004-0.89, p = 0.035). The present findings suggest that the Pro/Pro genotype of p53 codon 72 played a role in prostate cancer susceptibility in a Japanese population. However, the Pro allele did not appear to worsen such clinical parameters as clinical stage or pathological grade.

p53 Codon 72 polymorphism and urothelial cancer risk

The p53 tumor suppressor gene is often mutated in various human cancers. Recently, the p53 codon 72 polymorphism has been extensively studied to determine the risk factors responsible for cancer formation. We investigated the genotype distribution of the p53 codon 72 polymorphism in 112 male urothelial cancer cases and 175 male unrelated non-cancer controls. The allelic frequencies in Japanese non-cancer controls were 0.58 (Arg) and 0.42 (Pro). There was no significant difference in the three genotype frequencies (Arg/Arg, Arg/Pro, Pro/Pro) of the p53 codon 72 between the urothelial cancer cases and the controls. However, stratifying by smoking status, we found that the frequency of the Pro/Pro genotype for smokers was significantly more than that for never-smokers (odds ratio (OR)=2.28, 95% confidence interval (95%CI)=1.12-4.66). Furthermore, we divided smoking status (pack-years) into quartiles (<20, 20-40, 40-60, >60). OR (Pro/Pro vs. Arg/Arg) for the lighter smokers (<20 pack-years) was higher than in other groups (OR=6.83). Our results suggest that the Pro/Pro genotype of the p53 codon 72 polymorphism increases the risk of urothelial cancer in smokers.

Single nucleotide polymorphisms of estrogen receptor alpha in human renal cell carcinoma

Estrogens and their receptors (ERs) have been shown to play a role in various cancers. We hypothesize that polymorphisms and genotypic changes of the ERalpha gene are involved in renal cell carcinoma. To test this hypothesis, DNA samples from 113 cases of human renal cell cancer were analyzed by sequence-specific polymerase chain reaction to determine the genotypic frequency of six different polymorphic loci on ERalpha gene (codon 10 T-->C, codon 87 G-->C, codon 243 C-->T, codon 325 C-->G, codon 594 G-->A, and intron 1 C-->T). The relative risk of variant genotype was calculated by comparison with 200 healthy controls. The results of this study demonstrate that the distribution of genotypes on codon 10 differs between renal cancer patients and healthy normal controls (p<0.05). The relative risk of the genotype 10C/C was calculated as 2.51. No differences in genotypes were observed at all other loci. We also analyzed DNA from pairs of cancerous and normal tissues from 96 cases of human renal cell cancer to characterize genotypic changes at these loci. Genotypic changes were detected in nine cancer samples on exon 1 (codons 10 and 87) of ERalpha, although none were detected at other regions. The present study demonstrates for the first time that codon 10 polymorphism on exon 1 of ERalpha may be involved in renal cancer risk.

Association of codon 72 polymorphism of p53 with lower prostate cancer risk

BACKGROUND

A common germline polymorphism of p53 produces a protein with an Arg to Pro change at codon 72. This Pro variant has altered biochemical properties suggesting altered cancer susceptibility.

METHODS

A case control study with 115 men with prostate cancer and 181 community control male subjects was conducted. Demographics, family history of cancer, and blood were obtained. Codon 72 genotypes were determined using PCR.

RESULTS

The Pro/Pro genotype was associated with a markedly lower risk of prostate cancer (OR = 0.23, CI = 0.07-0.79, P = 0.012). Similar reduction in risk was observed when the analysis was limited to Caucasian subjects (86% of total). Reduction in risk remained significant in a logistic regression model after correcting for age and family history of prostate cancer (OR = 0.14, CI = 0.03-0.71, P = 0.017).

CONCLUSIONS

Men with the p53 codon 72 Pro/Pro genotype appear to be at reduced risk of prostate cancer.

p53 Polymorphism (codon-72) has no correlation with the development and the clinical features of cervical cancer

Recent analysis of the codon-72 polymorphism of the p53 gene, the allele encoding proline or arginine, suggested that the homozygous Arg/Arg genotype is a significant risk factor for cervical cancer associated with human papillomavirus (HPV). We investigated the polymorphism of p53 in cervical condylomas, cervical intraepithelial neoplasias (CINs), and cervical cancers, evaluating clinical implications of the polymorphism of p53 in development of cervical neoplasms. DNA from 87 cervical cancer tissues, 28 CIN tissues, and seven cervical condyloma tissues were examined for the presence of HPV DNA by the consensus PCR method and the p53 polymorphism was analyzed by PCR using an allele-specific primer. The frequencies of p53Pro, p53Arg, and p53 Pro/Arg were 14.3%, 57.1%, and 28.6% in condyloma patients; 21.4%, 39.3%, and 35.7% in CIN patients; and 10.3%, 44.8%, and 42.5% in cervical cancer patients, respectively. No statistically significant differences in the distribution of p53 genotypes were found among the patients with these diseases, regardless of HPV status. Furthermore, there was no clear correlation between the polymorphism of p53 and age, histopathologic type, clinical stage, or lymph node metastasis. Nor was there any evidence of a correlation between the p53 genotype and the outcome for patients with HPV-positive uterine cervical cancer.

Genetic alterations of the p16 gene in urothelial carcinoma in Taiwanese patients

OBJECTIVE

To measure changes in the p16 gene (MTS1, a negative regulator of cell-cycle progression at the G1 checkpoint, and a tumour suppressor gene) in urothelial carcinomas (including upper tract urothelial and bladder tumours), and to correlate these measurements with the clinical status of such patients in Taiwan, where renal pelvic tumours comprise 47% of all kidney tumours and are more common than the average worldwide.

MATERIALS AND METHODS

Thirty-five upper tract urothelial and 61 bladder tumours were examined for changes in p16. Deletion of the gene was assessed by Southern blot analysis and mutation analysed using polymerase chain reaction-single strand conformation polymorphism, followed by direct sequencing.

RESULTS

Of the 61 bladder carcinomas, homozygous deletion of p16 was detected in 12 (20%). However, a homozygous deletion was detected in 11 of 35 (31%) upper tract urothelial carcinomas, a higher frequency than that reported for transitional cell bladder carcinomas. Deletion was detected as frequently in stage I tumours as in late-stage tumours, suggesting that p16 deletion is a relatively early event in urothelial tumorigenesis. No point mutations were noted for p16 in any of the primary urothelial tumours. Most multiple and recurrent tumours and metastatic nodules in individual patients contained identical p16 genetic lesions, confirming that the tumours were probably monoclonal. In addition, there was a high gene dose of p16 in bladder carcinomas from patients with lymph node metastasis.

CONCLUSION

Deletion of p16 appears to be a common event in urothelial carcinomas, especially in upper tract urothelial tumours. High levels of p16 were detected in tumours with lymph node metastasis. It seems likely that a high p16 level is associated with carcinomas of advanced stage and grade, and with poor prognosis in patients with such cancers.

Search for mutations of the hRAD54 gene in sporadic meningiomas with deletion at 1p32

The hRAD54 gene is related to a family of genes involved in DNA recombination and repair and encodes a protein with DNA helicase activity. hRAD54 has been mapped to 1p32, a region frequently involved in deletions in a variety of tumor types, including atypical and anaplastic meningiomas. To determine whether alterations of hRAD54 are a common event in meningeal tumors, by means of polymerase chain reaction-single-stranded conformation analysis we examined 29 tumor samples characterized by 1p deletions for hRAD54 mutations. Although 18 tumors displayed allelic loss at the gene region (1p32) as determined by microsatellite marker analysis, the sole coding-sequence alteration detected corresponded to a T-->C transition, with no amino-acid change. The genotype distribution was 10.34% TT, 44.8% TC, and 44.8% CC, whereas in the normal controls it was 3.77% TT, 13.2% TC, and 83.01% CC, and most meningiomas with 1 p32 deletion retained allele C. Another polymorphism due to a T-->C change was evidenced at nt 3008, in the 3' untranslated region. This change was evidenced in all cases we sequenced. These results appear to exclude the involvement of the hRAD54 gene in the pathogenesis of the nontypical meningiomas, although a detrimental effect of the hRAD54 polymorphisms cannot be ruled out.

Mutated connexin43 proteins inhibit rat glioma cell growth suppression mediated by wild-type connexin43 in a dominant-negative manner

Many lines of evidence support the hypothesis that connexins form a family of tumor-suppressor genes. Transfection of connexin43 (Cx43) into rat C6 glioma cells have revealed that Cx43 functions as a growth- and tumor-suppressor in C6 cells. In previous studies, we and others have reported that several mutant connexins can inhibit gap junctional intercellular communication (GJIC) realized by the wild type in a dominant-negative manner. We have now examined dominant-negative effects of Cx43 mutants on cell growth control exerted by wild-type Cx43 in C6 cells. When 2 Cx43 mutants (L160M and A253V) were transfected into Cx43-transfected C6 cells, they restored anchorage-independent growth capacity and reinforced the tumorigenicity of these cells, meaning that these 2 mutants can inhibit growth-suppressive function of wild-type Cx43 in a dominant-negative manner. Neither of the mutants appeared to affect phosphorylation states and subcellular localization of Cx43 proteins. Intriguingly, the mutant A253V did not suppress GJIC capacity, implying a growth-suppressive pathway mediated by Cx43 may not be related to GJIC.

Nuclear p53 overexpression in bladder, prostate, and renal carcinomas

BACKGROUND

The aim of this study was to examine nuclear p53 overexpression in transitional cell carcinoma of the bladder, adenocarcinoma of the prostate, and renal cell carcinoma.

METHODS

Forty-four pathologic specimens from 39 bladder cancer patients, 41 prostatic adenocarcinoma, and 39 renal cell carcinoma specimens were analyzed immunohistochemically with D07 monoclonal antibody to detect the expression of the mutant p53 gene. Overexpression was said to occur when the number of positively-stained tumor nuclei were > or = 10% in each specimen. p53 overexpression was correlated with the clinical and histopathological features of these cancers.

RESULTS

Nuclear p53 overexpression occurred in 18.2% of transitional cell bladder cancer specimens, 12.2% of prostate cancer specimens, and 17.9% of renal cell cancer specimens. Statistical analyses showed that grade, vascular invasion, and necrosis in bladder cancer, a high Gleason score in prostate cancer, and the 1-year mortality rate in renal cancer were significantly related with p53 nuclear overexpression (P < 0.05).

CONCLUSION

Using the D07 monoclonal antibody, nuclear p53 overexpression is relatively uncommon in urologic malignancies, and moderately correlates with several histopathological and clinical features of urologic malignancies.

Molecular epidemiology in environmental health: the potential of tumor suppressor gene p53 as a biomarker

One of the challenges in environmental health is to attribute a certain health effect to a specific environmental exposure and to establish a cause-effect relationship. Molecular epidemiology offers a new approach to addressing these challenges. Mutations in the tumor suppressor gene p53 can shed light on past environmental exposure, and carcinogenic agents and doses can be distinguished on the basis of mutational spectra and frequency. Mutations in p53 have successfully been used to establish links between dietary aflatoxin exposure and liver cancer, exposure to ultraviolet light and skin cancer, smoking and cancers of the lung and bladder, and vinyl chloride exposure and liver cancer. In lung cancer, carcinogens from tobacco smoke have been shown to form adducts with DNA. The location of these adducts correlates with those positions in the p53 gene that are mutated in lung cancer, confirming a direct etiologic link between exposure and disease. Recent investigations have also explored the use of p53 as a susceptibility marker for cancer. Furthermore, studies in genetic toxicology have taken advantage of animals transgenic for p53 to screen for carcinogens in vivo. In this review, we summarize recent developments in p53 biomarker research and illustrate applications to environmental health.