Polymorphisms in XPD, XPC and the risk of death in patients with urinary bladder neoplasms

Systematic Review: Genetic Associations for Prognostic Factors of Urinary Bladder Cancer

INTRODUCTION

Many germline associations have been reported for urinary bladder cancer (UBC) outcomes and prognostic characteristics. It is unclear whether there are overlapping genetic patterns for various prognostic endpoints. We aimed to review contemporary literature on genetic associations with UBC prognostic outcomes and to identify potential overlap in reported genes.

METHODS

EMBASE, MEDLINE, and PubMed databases were queried for relevant articles in English language without date restrictions. The initial search identified 1346 articles. After exclusions, 112 studies have been summarized. Cumulatively, 316 single-nucleotide polymorphisms (SNPs) were reported across prognostic outcomes (recurrence, progression, death) and characteristics (tumor stage, grade, size, age, risk group). There were considerable differences between studied outcomes in the context of genetic associations. The most commonly reported SNPs were located in OGG1, TP53, and MDM2. For outcomes with the highest number of reported associations (ie, recurrence and death), functional enrichment annotation yields different terms, potentially indicating separate biological mechanisms.

CONCLUSIONS

Our study suggests that all UBC prognostic outcomes may have different biological origins with limited overlap. Further validation of these observations is essential to target a phenotype that could best predict patient outcome and advance current management practices.

Thyroid Cancer: The Quest for Genetic Susceptibility Involving DNA Repair Genes

The incidence of thyroid cancer (TC), particularly well-differentiated forms (DTC), has been rising and remains the highest among endocrine malignancies. Although ionizing radiation (IR) is well established on DTC aetiology, other environmental and genetic factors may also be involved. DNA repair single nucleotide polymorphisms (SNPs) could be among the former, helping in explaining the high incidence. To further clarify the role of DNA repair SNPs in DTC susceptibility, we analyzed 36 SNPs in 27 DNA repair genes in a population of 106 DTCs and corresponding controls with the aim of interpreting joint data from previously studied isolated SNPs in DNA repair genes. Significant associations with DTC susceptibility were observed for XRCC3 rs861539, XPC rs2228001, CCNH rs2230641, MSH6 rs1042821 and ERCC5 rs2227869 and for a haplotype block on chromosome 5q. From 595 SNP-SNP combinations tested and 114 showing relevance, 15 significant SNP combinations (p < 0.01) were detected on paired SNP analysis, most of which involving CCNH rs2230641 and mismatch repair variants. Overall, a gene-dosage effect between the number of risk genotypes and DTC predisposition was observed. In spite of the volume of data presented, new studies are sought to provide an interpretability of the role of SNPs in DNA repair genes and their combinations in DTC susceptibility.

Mismatch repair single nucleotide polymorphisms and thyroid cancer susceptibility

Thyroid cancer (TC) is the most common endocrine malignancy and its incidence continues to rise worldwide. Ionizing radiation exposure is the best established etiological factor. Heritability is high; however, despite valuable contribution from recent genome-wide association studies, the current understanding of genetic susceptibility to TC remains limited. Several studies suggest that altered function or expression of the DNA mismatch repair (MMR) system may contribute to TC pathogenesis. Therefore, the present study aimed to evaluate the potential role of a panel of MMR single nucleotide polymorphisms (SNPs) on the individual susceptibility to well-differentiated TC (DTC). A case-control study was performed involving 106 DTC patients and 212 age- and gender-matched controls, who were all Caucasian Portuguese. Six SNPs present in distinct MMR genes (MLH1 rs1799977, MSH3 rs26279, MSH4 rs5745325, PMS1 rs5742933, MLH3 rs175080 and MSH6 rs1042821) were genotyped through TaqMan^® assays and genotype-associated risk estimates were calculated. An increased risk was observed in MSH6 rs1042821 variant homozygotes [adjusted odds ratio (OR)=3.42, 95% CI: 1.04-11.24, P=0.04, under the co-dominant model; adjusted OR=3.84, 95% CI: 1.18-12.44, P=0.03, under the recessive model]. The association was especially evident for the follicular histotype and female sex. The association was also apparent when MSH6 was analysed in combination with other MMR SNPs such as MSH3 rs26279. Interestingly, two other SNP combinations, both containing the MSH6 heterozygous genotype, were associated with a risk reduction, suggesting a protective effect for these genotype combinations. These data support the idea that MMR SNPs such as MSH6 rs1042821, alone or in combination, may contribute to DTC susceptibility. This is coherent with the limited evidence available. Nevertheless, further studies are needed to validate these findings and to establish the usefulness of these SNPs as genetic susceptibility biomarkers for DTC so that, in the near future, cancer prevention policies may be optimized under a personalized medicine perspective.

Polymorphisms in the XPC gene affect urinary bladder cancer risk: a case-control study, meta-analyses and trial sequential analyses

Compromised activity of the DNA repair enzymes may raise the risk of a number of cancers. We analyzed polymorphisms in the Xeroderma Pigmentosum, Complementation Group C (XPC) gene for their correlation with urinary bladder cancer. Ala499Val and Lys939Gln polymorphisms were genotyped in 234 urinary bladder cancer cases and 258 control samples. A significant association between Ala499Val polymorphism and bladder cancer was observed (OR = 1.78, CI = 1.19–2.66, p = 0.005); however, Lys939Gln was unrelated (OR = 0.97, CI = 0.65–1.45, P = 0.89). Further analysis revealed that Ala499Val was a significant risk factor only in the presence of smoking (OR = 2.23, CI = 1.28–3.87, p < 0.004) or tobacco chewing (OR = 2.40, CI = 1.43–4.04, p = 0.0008). To further appraise the association, we undertook meta-analyses on seven studies (2893 cases and 3056 controls) on Ala499Val polymorphism and eleven studies (5064 cases and 5208 controls) on Lys939Gln polymorphism. Meta-analyses corroborated the above results, showing strong association of Ala499Val (OR = 1.54, CI = 1.21–1.97, p = 0.001) but not that of Lys939Gln (OR = 1.13, CI = 0.95–1.34, p = 0.171) with urinary bladder cancer risk. In conclusion, XPC Ala499Val substitution increases urinary bladder cancer risk, but Lys939Gln appears to be neutral.

XPC intron11 C/A polymorphism as a risk factor for prostate cancer

OBJECTIVES

DNA repair genes play an important role in protection against environmental and endogenous DNA damage, and constitute the first line of defense against cancer. Xeroderma pigmentosum complementation group C (XPC) is involved in the damage recognition step during nucleotide excision repair. The relationship between XPC intron11 C/A polymorphism and cancer risk has not been widely studied. Hence, this study evaluated the relationship between the XPC intron11 C/A polymorphism and prostate cancer risk.

MATERIALS AND METHODS

This hospital-based cohort consisted of 152 patients with prostate cancer and 142 male controls. The XPC intron11 C/A genotype was determined using the PCR-RFLP method. Medical, occupational, and cigarette-smoking history was obtained from each participant using questionnaires.

RESULTS

Logistic regression analysis revealed that compared to controls, the frequencies of the A/A and C/A genotypes were significantly higher than those of the C/C genotype in cancer patients (OR = 2.03, 95% confidence interval (CI) 1.03-3.98 and OR = 1.91, 95% CI 1.13-3.24, respectively). We also found that the frequency of the A/A genotype was significantly higher in cancer cases than in controls among non-smokers (OR = 7.7, 95% CI 1.38-42.88, compared to the C/C genotype).

CONCLUSION

We found that the XPC intron11 C/A polymorphism was associated with an increased risk of prostate cancer. Among non-smokers, the A/A genotype was significantly more prevalent in prostate cancer patients than in controls.

Independent Replication of Published Germline Polymorphisms Associated with Urinary Bladder Cancer Prognosis and Treatment Response

BACKGROUND

Many studies investigated the prognostic or predictive relevance of single nucleotide polymorphisms (SNPs) in biologically plausible genes in urinary bladder cancer (UBC) patients. Most published SNP associations have never been replicated in independent patient series.

OBJECTIVE

To independently replicate all previously reported associations between germline SNPs and disease prognosis or treatment response in UBC.

METHODS

A Pubmed search was performed to identify studies published by July 1, 2014 reporting on germline SNP associations with UBC prognosis or treatment response. For the replication series, consisting of 1,284 non-muscle-invasive bladder cancer (NMIBC) and 275 muscle-invasive or metastatic bladder cancer (MIBC) patients recruited through the Netherlands Cancer Registry, detailed clinical data were retrieved from medical charts. Patients were genotyped using a genome-wide SNP array. SNP association with recurrence-free, progression-free, and overall survival (OS) within specific patient and treatment strata was tested using Cox regression analyses.

RESULTS

For only six of the 114 evaluated SNPs, the association with either UBC prognosis or treatment response was replicated at the p <  0.05 level: rs1799793 (ERCC2) and rs187238 (IL18) for BCG recurrence; rs6678136 (RGS4) and rs11585883 (RGS5) for NMIBC progression; rs12035879 (RGS5) and rs2075786 (TERT) for MIBC OS.

CONCLUSIONS

Non-replicated genetic associations in the literature require cautious interpretation. This single replication does not provide definitive proof of association for the six SNPs, and non-replication of other SNPs may result from population-specific effects or the retrospective patient enrollment.

H2AX phosphorylation level in peripheral blood mononuclear cells as an event-free survival predictor for bladder cancer

Bladder cancer (BC) has a typical aetiology characterized by a multistep carcinogenesis due to environmental exposures, genetic susceptibility, and their interaction. Several lines of evidence suggest that DNA repair plays a role in the development and progression of BC. In particular, the study of individual susceptibility to DNA double strand breaks (DSBs) may provide valuable information on BC risk, and help to identify those patients at high-risk of either recurrence or progression of the disease, possibly personalizing both surveillance and treatment. Among the different DSB markers, the most well characterized is phosphorylation of the histone H2AX (γ-H2AX). We assessed any potential role of γ-H2AX as a molecular biomarker in a case-control study (146 cases and 146 controls) to identify individuals with increased BC risk and at high-risk of disease recurrence or progression. We investigated γ-H2AX levels in peripheral blood mononuclear cells before and after their exposure to ionizing radiation (IR). We did not find any significant difference among cases and controls. However, we observed a significant association between γ-H2AX basal levels and risk of disease recurrence or progression. In particular, both BC patients as a whole and the subgroup of non-muscle invasive BC (NMIBC) with high basal H2AX phosphorylation levels had a decreased risk of recurrence or progression (for all BC HR 0.70, 95%CI 0.52-0.94, P = 0.02; for NMIBC HR 0.68, 95%CI 0.50-0.92, P = 0.01), suggesting a protective effect of basal DSB signaling. Our data suggest that γ-H2AX can be considered as a potential molecular biomarker to identify patients with a higher risk of BC recurrence. © 2015 Wiley Periodicals, Inc.

The Cellular Response to Oxidatively Induced DNA Damage and Polymorphism of Some DNA Repair Genes Associated with Clinicopathological Features of Bladder Cancer

Genome instability and impaired DNA repair are hallmarks of carcinogenesis. The study was aimed at evaluating the DNA damage response in H2O2-treated lymphocytes using the alkaline comet assay in bladder cancer (BC) patients as compared to clinically healthy controls, elderly persons, and individuals with chronic inflammations. Polymorphism in DNA repair genes involved in nucleotide excision repair (NER) and base excision repair (BER) was studied using the PCR-RFLP method in the Belarusian population to elucidate the possible association of their variations with both bladder cancer risk and clinicopathological features of tumors. The increased level of H2O2-induced DNA damage and a higher proportion of individuals sensitive to oxidative stress were found among BC patients as compared to other groups under study. Heterozygosity in the XPD gene (codon 751) increased cancer risk: OR (95% CI) = 1.36 (1.03-1.81), p = 0.031. The frequency of the XPD 312Asn allele was significantly higher in T ≥ 2 high grade than in T ≥ 2 low grade tumors (p = 0.036); the ERCC6 1097Val/Val genotype was strongly associated with muscle-invasive tumors. Combinations of homozygous wild type alleles occurred with the increased frequency in patients with non-muscle-invasive tumors suggesting that the maintenance of normal DNA repair activity may prevent cancer progression.

XRCC1 polymorphisms associated with survival among Chinese bladder cancer patients receiving epirubicin and mitomycin C

The association between DNA repair gene polymorphisms and bladder cancer risk has been widely studied. However, only few studies have examined the correlation between bladder cancer and instillation agent sensitivity. The aim of this study was to examine the association between polymorphisms of DNA repair genes, namely X-ray repair cross-complementing group I (XRCC1) rs2854509 and rs3213255, and bladder cancer recurrence risk. We recruited 244 patients (130 treated with epirubicin and 114 treated with mitomycin C). Genomic DNA was used to examine the XRCC1 rs2854509 and rs3213255 genotypes by Taqman PCR analysis. Combination analysis of XRCC1 rs2854509 and rs3213255 and examination of XRCC1 diplotypes were performed to reveal possible correlations. The rs2854509 CC and rs3213255 TT genotypes conferred shorter survival times than the rs2854509 AC/AA and rs3213255 CC/CT genotypes in patients treated with epirubicin, but not in those treated with mitomycin C (MMC) in adjusted models [hazard ratio (HR) = 0.23, 95 % confidence interval (CI) = 0.10-0.53 for rs2854509 AC + AA compared with CC; HR = 0.17, 95 % CI = 0.06-0.46 for rs3213255 CC + CT compared with TT]. Combination analysis showed significantly increased recurrence-free survival (RFS) among patients simultaneously carrying the rs2854509 AC/AA and rs3213255 CC/CT genotypes with an HR of 0.15 (95 % CI = 0.05-0.45) compared to those carrying other genotypes. Diplotype analysis demonstrated that the A-C/C-T diplotype is associated with a lower risk of recurrence compared with the common wild C-T/C-T diplotype (HR = 0.17, 95 % CI = 0.06-0.51). Our results suggest that the rs2854509 CC and rs3213255 TT genotypes confer higher sensitivity to epirubicin instillation. Moreover, the A-C/C-T diplotype presents significantly lower recurrence risk than other diplotypes.

DNA repair gene XRCC1 polymorphisms, smoking, and bladder cancer risk: a meta-analysis

Background and Objective

The X-ray repair cross-complementing group 1 (XRCC1) protein plays a crucial role in base excision repair (BER) pathway by acting as a scaffold for other BER enzymes. Variants in the XRCC1 gene might alter protein structure or function or create alternatively spliced proteins which may influence BER efficiency and hence affect individual susceptibility to bladder cancer. Recent epidemiological studies have shown inconsistent associations between these polymorphisms and bladder cancer. To clarify the situation, a comprehensive meta-analysis of all available studies was performed in this study.

Methods

PubMed, EMBASE, and Chinese Biomedical Literature database (CBM) databases have been systematically searched to identify all relevant studies for the period up to February 2013. Data were abstracted independently by two reviewers and Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed mainly by ethnicity and smoking status.

Results

A total of 26 case-control studies, including 24 studies for R399Q polymorphism, 15 studies for R194W polymorphism, and 7 studies for R280H polymorphism met the inclusion criteria and were selected. With respect to R399Q polymorphism, significantly decreased bladder cancer risk was found among smokers (AA vs. GG: OR=0.693, 95%CI= 0.515-0.932, P=0.015 and recessive model AA vs. GA+GG: OR=0.680, 95%CI= 0.515-0.898, P=0.007, respectively). With respect to R194W and R280H polymorphism, significantly increased bladder cancer risk were observed among Asians (TT+CT vs. CC:OR = 1.327, 95% CI 1.086-1.622, P=0.006 for R194W, and AA+GA vs. GG: OR=2.094, 95% CI 1.211–3.621, P=0.008 for R280H, respectively).

Conclusions

This meta-analysis suggests that the XRCC1 R399Q polymorphism may play a protective role against bladder cancer among smokers. However, the XRCC1 R194W and R280H polymorphisms were both associated with increased bladder cancer risk among Asians. Further studies with larger sample sizes are needed to validate our finds.

Study on bladder cancer susceptibility and genetic polymorphisms of XPC, XPG, and CYP in smokers and non-smokers

AIM

To investigate the gene susceptibility of bladder cancer and potential relation with smoking.

METHODS

An analysis of SNPs were conducted among DNA repair genes of XPC, XPG, XRCC1, and six members of metabolic enzyme gene CYP 450 via TaqMan Probe-based polymerase chain reaction. A total of 130 patients with bladder cancer and 304 healthy controls were involved.

RESULTS

Polymorphisms of XPC gene was related to bladder cancer. It was also related to smoking status in bladder cancer patients, as well as to tumour stage, male gender and older age. The XPG gene polymorphism was also related to bladder cancer yet it was prevalent in female non-smokers. No association was acquired for XRCC1 gene. The combination of more than 2 polymorphisms in DNA repair genes was associated with bladder cancer. No association was obtained in any of the metabolic enzyme gene of CYP450 with either bladder cancer or smoking status.

CONCLUSION

DNA repair genes XPC and XPG could be related to carcinogenesis and tumour progression of bladder cancer. Confirmation within larger population was warranted.

XRCC1 Arg399Gln polymorphism and bladder cancer risk: updated meta-analyses based on 5767 cases and 6919 controls

Previous reports implicate XRCC1 Arg399Gln polymorphism as a possible risk factor for several cancers. Published meta-analyses have been conducted on the association of XRCC1 Arg399Gln polymorphism with susceptibility to bladder cancer, and have generated conflicting results. The present study aimed to derive a more precise estimation of the relationship. Updated meta-analyses assessing the association of XRCC1 Arg399Gln polymorphism with bladder cancer were conducted and subgroup analyses on ethnicity, smoking status and source of controls were further performed. Eligible studies were identified for the period up to May 2012. A total of 19 case-control studies comprising 5767 cases and 6919 controls were lastly selected for analysis. The overall data failed to indicate significant associations between XRCC1 Arg399Gln polymorphism and bladder cancer risk (Gln/Gln versus Arg/Arg: odds ratio (OR) = 0.97; 95% CI = 0.85-1.10; dominant model: OR = 1.02; 95% CI = 0.94-1.09; recessive model: OR = 0.95; 95% CI = 0.84-1.07). In subgroup analyses stratified by ethnicity, smoking status and source of controls, respectively, similar results were obtained. In conclusion, the results of the present study suggest that XRCC1 Arg399Gln polymorphism might not modify the susceptibility to bladder cancer. Further large and well-designed studies are needed to confirm this conclusion.

Polymorphisms in the XRCC1 gene modify survival of bladder cancer patients treated with chemotherapy

Survival of bladder cancer patients depends on several factors including disease stage and grade at diagnosis, age, health status of the patient and the applied treatment. Several studies investigated the role of DNA repair genetic variants in cancer susceptibility, but only few studies investigated their role in survival and response to chemotherapy for bladder cancer. We genotyped 28 single nucleotide polymorphisms (SNP) in DNA repair genes in 456 bladder cancer patients, reconstructed haplotypes and calculated a score for combinations of the SNPs. We estimated Hazard Ratios (adjHR) for time to death. Among patients treated with chemotherapy, variant alleles of five SNPs in the XRCC1 gene conferred better survival (rs915927 adjHR 0.55 (95%CI 0.32-0.94); rs76507 adjHR 0.48 (95%CI 0.27-0.84); rs2854501 adjHR 0.25 (95%CI 0.12-0.52); rs2854509 adjHR 0.21 (95%CI 0.09-0.46); rs3213255 adjHR 0.46 (95%CI 0.26-0.80). In this group of patients, an increasing number of variant alleles in a XRCC1 gene score were associated with a better survival (26% decrease of risk of death for each additional variant allele in XRCC1). By functional analyses we demonstrated that the previous XRCC1 SNPs confer lower DNA repair capacity. This may support the hypothesis that survival in these patients may be modulated by the different DNA repair capacity determined by genetic variants. Chemotherapy treated cancer patients bearing an increasing number of "risky" alleles in XRCC1 gene had a better survival, suggesting that a proficient DNA repair may result in resistance to therapy and shorter survival. This finding may have clinical implications for the choice of therapy.

Germline prognostic markers for urinary bladder cancer: obstacles and opportunities

Urinary bladder cancer is a heterogeneous disease with diverse genetic and environmental risk factors that can influence disease risk or clinical course for recurrence, progression, and survival. Therefore, identification of these factors is paramount for disease prevention and optimal clinical management of bladder cancer patients. Of particular interest is the need to identify molecular biomarkers that can give accurate assessment of tumor biological potential and to predict treatment response. Recent advances in molecular biology, cytogenetic, and genomic research have spurred discovery efforts for novel genetic, epigenetic, and proteomic biomarkers that are prognostic for cancer. This review focuses on some of the important germ line polymorphisms found to be correlated with clinical outcomes in bladder cancer. So far, most of the identified candidate loci were based on prior knowledge of pathogenesis and had not been validated for clinical applications. The future challenges are to analyze the wealth of information from whole-genome studies, to understand the underlying biological mechanisms of these associations, the network of gene-gene and gene-environment interactions, and to apply these markers for the identification of high-risk population for targeted, personalized therapy.

Smoking and polymorphisms in xenobiotic metabolism and DNA repair genes are additive risk factors affecting bladder cancer in Northern Tunisia

Cancer epidemiology has undergone marked development since the nineteen-fifties. One of the most spectacular and specific contributions was the demonstration of the massive effect of smoking and genetic polymorphisms on the occurrence of bladder cancer. The tobacco carcinogens are metabolized by various xenobiotic metabolizing enzymes, such as the super-families of N-acetyltransferases (NAT) and glutathione S-transferases (GST). DNA repair is essential to an individual's ability to respond to damage caused by tobacco carcinogens. Alterations in DNA repair genes may affect cancer risk by influencing individual susceptibility to this environmental exposure. Polymorphisms in NAT2, GST and DNA repair genes alter the ability of these enzymes to metabolize carcinogens or to repair alterations caused by this process. We have conducted a case-control study to assess the role of smoking, slow NAT2 variants, GSTM1 and GSTT1 null, and XPC, XPD, XPG nucleotide excision-repair (NER) genotypes in bladder cancer development in North Tunisia. Taken alone, each gene unless NAT2 did not appear to be a factor affecting bladder cancer susceptibility. For the NAT2 slow acetylator genotypes, the NAT2*5/*7 diplotype was found to have a 7-fold increased risk to develop bladder cancer (OR = 7.14; 95% CI: 1.30-51.41). However, in tobacco consumers, we have shown that Null GSTM1, Wild GSTT1, Slow NAT2, XPC (CC) and XPG (CC) are genetic risk factors for the disease. When combined together in susceptible individuals compared to protected individuals these risk factors give an elevated OR (OR = 61). So, we have shown a strong cumulative effect of tobacco and different combinations of studied genetic risk factors which lead to a great susceptibility to bladder cancer.

Germline genetic markers for urinary bladder cancer risk, prognosis and treatment response

After decades of research using a candidate gene approach, only NAT2 and GSTM1 have consistently been demonstrated to be germline genetic susceptibility markers for urinary bladder cancer (UBC). The recent shift to an agnostic genome-wide association approach led to the identification of several UBC susceptibility loci, and provided valuable leads for new mechanistic insights into UBC carcinogenesis. The markers do not have sufficient discriminatory ability yet to be applied for risk assessment in the population and the question is whether they ever will. Prognostic and predictive studies in UBC are still in their infancy compared with etiologic studies. In the future, focus on a genome-wide association approach possibly using whole-genome sequence data, consortia formation and meta-analyses, and blood and tumor tissue collection, preferably in the context of randomized controlled trials will stimulate well designed and sufficiently powered studies, and thereby enhance the elucidation of genetic prognostic and predictive markers.

An association between DNA repair gene polymorphisms and survival in patients with resected non-small cell lung cancer

DNA repair genetic polymorphisms have been studied extensively in relation to lung cancer susceptibility, but much less is known about their role in clinical outcome modulation. In this report, we examined effect of the XPA -4G>A, XPD Asp312Asn, Leu751Gln, hHR23B Ala249Val, XPG Asp1104His, XRCC1 Arg399Gln, XRCC2 -4234G>C and XRCC3 Thr241Met polymorphisms on overall survival in 162 patients with resected non-small cell lung cancer (NSCLC). The XRCC3 Met/Met genotype was significantly associated with increased risk of death among all patients and men in uni- and multivariate analyses. The risk was higher for adenocarcinoma patients possessing the XRCC3 Met/Met or XRCC1 Gln/Gln genotypes, although their frequency was small. The XRCC1 399Gln allele was also associated with poor prognosis in stage II-IIIA and among older individuals. Men homozygous for the XPD 312 Asn/Asn had significantly better survival with the risk of death being at borderline significance in uni- and multivariate models. Younger cases and ever smokers smoking less than median pack-years showed significantly increased risk of death associated with the XPA -4A allele. A presence of one or two XRCC2 -4234C alleles had a protective effect in males and ever smokers with lower cumulative smoking dose, although the CC genotype was rarely observed. When number of combined risk alleles was considered, we found that carriers of >4 adverse alleles were at significantly increased risk of death in uni- and multivariate models. Therefore, our results indicate that selected genetic polymorphisms in DNA repair genes may influence overall survival in resected NSCLC.

Tissue hOGG1 genotype predicts bladder cancer prognosis: a novel approach using a peptide nucleic acid clamping method

BACKGROUND

Tissue genotyping is a more useful approach than using blood genomic DNA, because the tumor tissues can reflect the effects of somatic mutations in cancer. We investigated the value of the human oxoguanine glycosylase (hOGG1) genotype determined in tumor tissues as a prognostic indicator for bladder cancer (BC) using a novel technological approach.

METHODS

A total of 335 DNA samples from patients with primary BC were analyzed by peptide nucleic acid (PNA)-mediated real-time polymerase chain reaction (PCR) clamping to characterize the association between genetic polymorphisms within hOGG1 codon 326 and the clinicopathological characteristics of primary BC patients.

RESULTS

Tumor stage and number were significantly associated with the hOGG1 codon 326 genotype in nonmuscle invasive bladder cancer (NMIBC) patients. Compared with Cys326Ser and Ser326Ser, the Cys326Cys genotype had a greater progression-free survival benefit in patients with muscle invasive bladder cancer (MIBC). Univariate and multivariate Cox regression analyses indicated that the hOGG1 Cys326Cys genotype has a protective effect against progression in MIBC (hazard ratio, 0.360 and 0.314, respectively).

CONCLUSIONS

The hOGG1 tissue genotype is associated with aggressive clinicopathological features in NMIBC and with progression in patients with MIBC. Results suggest that the hOGG1 tissue genotype represents a promising marker for assessing BC prognosis in the clinical setting.

Analysis of hOGG1 genotype as a prognostic marker for muscle invasive bladder cancer: a novel approach using peptide nucleic acid-mediated, real-time PCR clamping

OBJECTIVE

DNA damage repair mechanisms are a source of genetic mutation and are believed to play an important role in human cancer. Human 8-oxoguanine DNA glycosylase 1 (hOGG1) is involved in the recognition and repair of DNA damage. The value of the hOGG1 genotype as a prognostic indicator for bladder cancer (BC) was assessed using a novel technological approach.

MATERIALS AND METHODS

The association between genetic polymorphisms of hOGG1 codon 326 and clinicopathologic characteristics of 337 patients with BC was analyzed using peptide nucleic acid (PNA)-mediated real-time PCR clamping.

RESULTS

Tumor grade and size were significantly associated with the hOGG1 codon 326 genotype in non-muscle-invasive bladder cancer (NMIBC). The Cys326Cys polymorphism was significantly associated with progression and cancer specific survival in patients with muscle-invasive bladder cancer (MIBC). Multivariate Cox regression analysis indicated that the hOGG1 Cys326Cys polymorphism is associated with a protective effect on progression and a more dominant survival benefit than the Ser326Ser polymorphism in MIBC (hazard ratio 0.284 and 0.305, respectively).

CONCLUSIONS

Analysis of genotypes and clinical data for 337 BC patients indicates that the hOGG1 genotype may be a useful prognostic genetic marker for MIBC.

Do DNA repair genes OGG1, XRCC3 and XRCC7 have an impact on susceptibility to bladder cancer in the North Indian population?

OBJECTIVE

Polymorphisms in DNA repair genes may be associated with altered DNA repair capacity, thereby influencing an individual's susceptibility to smoking-related cancers such as bladder cancer. Therefore, we sought to examine the correlation between single nucleotide polymorphisms in DNA repair genes and bladder cancer.

METHODOLOGY

We undertook a case-control study of 212 urothelial bladder cancer (UBC) cases and 250 controls to investigate the association between OGG1 (C1245G rs1052133), XRCC3 (C18067T, rs861539) and XRCC7 (G6721T, rs7003908) polymorphisms and bladder cancer susceptibility by PCR-RFLP and the ARMS method. We also investigated gene-environment interactions.

RESULTS

The OGG1 GG genotype was associated with an elevated risk of urothelial bladder cancer (UBC) (OR, 2.10; p, 0.028). XRCC7 + 6721 GG was also associated with increased susceptibility to UBC (OR, 4.45; p, 0.001). In a recessive model, the OGG1 GG genotype showed an increased risk of TaG(2,3) + T1G(1-3) tumors. Additionally, the OGG1 GG genotype in non-smokers represented a 2.46-fold greater risk (OR, 2.46; p, 0.035) in bladder cancer patients. Subsequent analysis demonstrated more pronounced association of XRCC7 with smokers (OR, 4.39; p, 0.001). XRCC7 also showed increased association with TaG(2,3) + T1G(1-3) tumors and muscle invasive tumors (OR, 3.16; p, 0.001 and OR, 4.24; p, 0.001, respectively). Multiple Cox regression analysis in non-muscle invasive bladder tumor (NMIBT) patients demonstrated an association of the OGG1 GG polymorphism with a high risk of recurrence in patients on cystoscopic surveillance (HR, 4.04; p, 0.013). Subsequently, shorter recurrence-free survival (log rank p, 0.024; CC/GG, 42/24) was observed.

CONCLUSION

Our data suggest association of a variant (GG) genotype of OGG1 with increased UBC susceptibility and a high risk of tumor recurrence in NMIBT patients on cystoscopic surveillance. XRCC7 G allele carriers (TG+GG) are also at an elevated risk for susceptibility to UBC as evidenced by a high odds ratio throughout the analysis.

Bladder cancer SNP panel predicts susceptibility and survival

Bladder cancer is the fourth most common malignancy in men and the eighth most common in women in western countries. Single nucleotide polymorphisms (SNPs) in genes that regulate telomere maintenance, mitosis, inflammation, and apoptosis have not been assessed extensively for this disease. Using a population-based study with 832 bladder cancer cases and 1,191 controls, we assessed genetic variation in relation to cancer susceptibility or survival. Findings included an increased risk associated with variants in the methyl-metabolism gene, MTHFD2 (OR 1.7 95% CI 1.3-2.3), the telomerase TEP1 (OR 1.8 95% CI 1.2-2.6) and decreased risk associated with the inflammatory response gene variant IL8RB (OR 0.6 95% CI 0.5-0.9) compared to wild-type. Shorter survival was associated with apoptotic gene variants, including CASP9 (HR 1.8 95% CI 1.1-3.0). Variants in the detoxification gene EPHX1 experienced longer survival (HR 0.4 (95% CI 0.2-0.8). These genes can now be assessed in multiple study populations to identify and validate SNPs appropriate for clinical use.

Impact of nucleotide excision repair ERCC2 and base excision repair APEX1 genes polymorphism and its association with recurrence after adjuvant BCG immunotherapy in bladder cancer patients of North India

BACKGROUND

Altered DNA repair capacity due to polymorphisms in DNA repair genes may modify response to Bacillus Calmette-Guerin (BCG) immunotherapy for high risk superficial bladder cancer (SBC).We evaluated the prospective outcome of exicision repair cross complementing group 2 (ERCC2) and apurinic/apyriminidic endonuclease (APEX1) gene in tumor recurrence after BCG immunotherapy in SBC patients.

MATERIALS AND METHODS

The study included 135 SBC patients, of which BCG immunotherapy was received by 74 patients. Genotyping was performed for ERCC2 Asp(312)Asn (G > A), Lys751Gln (A > C), and APEX1 Asp(148)Glu (T > G) polymorphisms by restriction fragment length polymorphism PCR and amplification refractory mutation system (ARMS) methods.

RESULTS

Multiple Cox regression analysis demonstrated association of variant genotype of ERCC2 (312)AA polymorphism with high risk of recurrence in BCG treated patients (HR = 3.07, P = 0.016, P ( c ) = 0.048). Patients with the ERCC2 (312)AA polymorphic genotypes showed shorter recurrence free survival (log-rank, P = 0.005; AA/GA + AA = 14/44) who received BCG treatment. Overall, risk of recurrence in bladder cancer was observed with smokers and size of tumors (1-3 cm) (HR = 1.86, P = 0.023 and HR = 3.19, P = 0.031, respectively). Smokers were identified to be at elevated risk in BCG treated patients (HR = 2.84, P = 0.005). No association was observed with the (ERCC2 Lys(751)Gln and APEX1 Asp(148)Glu) polymorphisms and risk of recurrence.

CONCLUSION

Our data suggested variant (AA) of ERCC2 312 AA genotype to be associated with high risk of tumor recurrence and reduced recurrence free survival in superficial bladder cancer patients.

Molecular epidemiology of DNA repair genes in bladder cancer

Bladder cancer is a common disease, whose major risk factors include smoking and occupational exposure to chemicals. Superficial bladder cancer has significant healthcare cost implications due to the need for repeated cystoscopic surveillance. Chemical carcinogens can undergo metabolic activation and detoxification in the liver and polymorphisms in the relevant genes have been shown to be associated with bladder cancer risk. In addition, DNA repair enzymes are required to repair the DNA damage associated with carcinogen exposure. The main pathways involved are nucleotide excision repair, base excision repair, and double strand break repair. Investigation of individual polymorphisms in DNA repair genes in bladder cancer has yielded few robust positive findings, which is not surprising given the multifactorial nature of the disease. Pathway approaches using novel genotyping technologies will allow more comprehensive studies of multiple polymorphisms in multiple genes. It will also be possible to investigate gene-environment interaction more rigorously than heretofore, using novel statistical methodology, in larger studies and through collaborative efforts within consortia. The results of the genome-wide association studies in bladder cancer are awaited with interest. In the future, genetic tests might be used in the prevention of bladder cancer to encourage lifestyle changes in those at highest risk of developing the disease, and in the treatment of bladder cancer to optimise cure rates whilst minimising morbidity in a cost-effective manner.

DNA repair gene polymorphisms may be associated with prognosis of upper urinary tract transitional cell carcinoma

Upper urinary tract transitional cell carcinoma (UUT-TCC) is quite an uncommon disease, and its prognosis differs among individuals irrespective of tumor stage. DNA repair gene polymorphisms are reported to result in the modulation of the repair capacity and might influence the prognosis of UUT-TCC. We examined the associations between functional polymorphisms in five DNA repair genes, and the prognosis of UUT-TCC in 103 UUT-TCC patients. Variant alleles in xeroderma pigmentosum complementation group C, more than three total variant alleles in all DNA repair genes studied and more than two total variant alleles in three nucleotide excision repair genes were independently associated with improved overall and disease-specific survival of UUT-TCC patients in multivariate analysis (P = .0063 and P = .0005 for xeroderma pigmentosum complementation group C, P = .016 and P = .0016 for all genes, and P = .0053 and P = .018 for nucleotide excision repair genes, respectively). These results suggest that some DNA repair gene polymorphisms may preoperatively be valuable as prognostic factors for UUT-TCC beyond tumor stage and grade, helping to provide optimal treatment strategies for individual patients.