DNA adducts in urothelial cells: relationship with biomarkers of exposure to arylamines and polycyclic aromatic hydrocarbons from tobacco smoke

Global trends in the epidemiology of bladder cancer: challenges for public health and clinical practice

Bladder cancer is among the ten most common cancers globally, causes considerable morbidity and mortality and is, therefore, a substantial burden for health-care systems. The incidence of bladder cancer is affected by demographic trends, most notably population growth and ageing, as well as exposure to risk factors, especially tobacco smoking. Consequently, the incidence has not been stable throughout the world over time, nor will it be in the near future. Further primary prevention efforts are of the utmost importance to reduce the medical and financial burden of bladder cancer on populations and health-care systems. Simultaneously, less-invasive and lower-cost approaches for the diagnosis of both primary and recurrent bladder cancers are required to address challenges posed by the increasing shortage of health-care professionals and limited financial resources worldwide. In this regard, urinary biomarkers have demonstrated promising diagnostic accuracy and efficiency. Awareness of the risk factors and symptoms of bladder cancer should also be increased in society, particularly among health-care professionals and high-risk groups. Studies investigating the associations between lifestyle factors and bladder cancer outcomes are scarce and should be a research priority. In this Review, we outline global trends in bladder cancer incidence and mortality, and discuss the main risk factors influencing bladder cancer occurrence and outcomes. We then discuss the implications, challenges and opportunities of these epidemiological trends for public health and clinical practice.

Human Papillomavirus 58 E7 T20I/G63S Variant Isolated from an East Asian Population Possesses High Oncogenicity

Human papillomavirus (HPV) type 58 is the third most commonly detected HPV type in cervical cancer among Eastern Asians. Our previous international epidemiological studies revealed that HPV58 carrying an E7 natural variant, T20I/G63S (designated V1), was associated with a higher risk of cervical cancer. We recently showed that V1 possesses a greater ability to immortalize and transform primary cells, as well as degrading pRB more effectively, than the prototype and other common variants. In this study, we performed a series of phenotypic and molecular assays using physiologically relevant in vitro and in vivo models to compare the oncogenicity of V1 with that of the prototype and other common natural variants. Through activation of the AKT and K-Ras/extracellular signal-regulated kinase (ERK) signaling pathways, V1 consistently showed greater oncogenicity than the prototype and other variants, as demonstrated by increased cell proliferation, migration, and invasion, as well as induction of larger tumors in athymic nude mice. This study complements our previous epidemiological and molecular observations pinpointing the higher oncogenicity of V1 than that of the prototype and all other common variants. Since V1 is more commonly found in eastern Asia, our report provides insight into the design of HPV screening assays and selection of components for HPV vaccines in this region.IMPORTANCE Epidemiological studies have revealed that a wild-type variant of HPV58 carrying an E7 variation, T20I/G63S (V1), is associated with a higher risk of cervical cancer. We previously reported that this increased oncogenicity could be the result of the virus's greater ability to degrade pRB, thereby leading to an increased ability to grow in an anchorage-independent manner. In addition to this, this report further showed that this HPV variant induced activation of the AKT and K-Ras/ERK signaling pathways, thereby explaining its genuine oncogenicity in promoting cell proliferation, migration, invasion, and formation of tumors, all to a greater extent than the prototype HPV58 and other common variants.

Correlation of IL-31 gene polymorphisms with susceptibility and clinical recurrence of bladder cancer

Interleukin-31 is a crucial cytokine triggering inflammation which could be one of the risk factors of tumors. However, data for correlation between IL-31 and tumors are limited. The purpose of our study was to discuss whether genetic polymorphisms of IL-31 were associated with the susceptibility and clinical outcomes of bladder cancer. Our study enrolled 478 controls, 156 non-muscle-invasive bladder cancer (NMIBC) and 138 muscle-invasive bladder cancer (MIBC) patients. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used for genotyping two single nucleotide polymorphisms (SNPs) of IL-31 gene including rs7977932 and rs4758680. Our results showed that A allele and CA/AA genotypes of rs4758680 were associated with susceptibility to bladder cancer (P = 0.04, OR 1.32, 95% CI 1.01-1.72, and P = 0.02, OR 1.43, 95% CI 1.05-1.96, respectively), and G allele of rs7977932 might be a protect factor for tobacco smoking patients compared with non-smoking patients (P = 0.005, OR 0.42, 95% CI 0.23-0.76). Furthermore, CA/AA genotypes of rs4758680 might be the independent risk factors for the decreased recurrence-free survival of the patients with MIBC (P = 0.03, OR 2.02, 95% CI 1.06-3.85. Our data indicated that polymorphisms of IL-31 are associated with bladder cancer, and rs4758680 could be an independent prediction for MIBC patients with a high risk of recurrence.

Role of polycyclic aromatic hydrocarbons as a co-factor in human papillomavirus-mediated carcinogenesis

BACKGROUND

Human papillomavirus (HPV) is an etiological agent of cervical cancer. Yet co-factors are believed to be involved in HPV-mediated carcinogenesis. Polycyclic aromatic hydrocarbons (PAHs) are considered as one of these co-factors. Epidemiologic studies have associated high PAH exposure with increased risk for cancer development. To date, many studies focus on benzo[a]pyrene, however, the role of other PAHs should not be neglected. This study aimed to compare the potential of different PAHs as a co-factor in HPV-mediated carcinogenesis, and to investigate the possible mechanisms involved.

METHODS

The effect of 17 PAHs on high-risk HPV (HPV16) were examined in this study. HPV16 E7 oncogene was expressed in primary cells extracted from baby rat kidney and treated with PAHs. The co-transforming ability of PAHs were measured by colony formation index according to the number and size of transformed colonies. Effects of PAHs on proliferation of HPV-null (C33A) and -infected (CaSki) were examined using CCK-8 assay. Wound healing assay and matrigel invasion chambers were used to investigate effects of PAHs on cell motility and invasivion of HPV-null (MCF7, C33A) and -infected (SiHa) cells.

RESULTS

Benzo[a]pyrene (BaP), dibenz[a,h]anthracene (DBA) and indeno[1,2,3-cd]pyrene (IDP) showed the greatest co-transforming potential in the baby rat kidney cell system. Short-term exposure to BaP, DBA, IDP and pyrene (PR) did not affect proliferation of C33A or CaSki cells, however, long-term exposure of these four PAHs led to dramatic increase in growth rate of CaSki cells by 120-140%. Besides, exposure of PAHs has an effect on cell motility and invasiveness of C33A and SiHa cells, but not for MCF7 cells. Exposure of BaP and DBA enhanced migration (1.26 to 1.40-fold) and invasion (1.68 to 1.94-fold) capacity of C33A cells. Intriguingly, exposure of all four types of PAHs boosted the migration (1.12 to 1.28-fold) and invasion (1.26 to 1.40-fold) capacity of SiHa cells.

CONCLUSIONS

Our results indicate that exposure to PAHs can be a key co-factor in HPV-related cancer development. They could act on all three stages, namely initiation, promotion and progression. Further study is needed to unveil the mechanisms by which PAHs interact with HPV to cause malignancy.

Polymorphisms of TNF-α -308 G/A and IL-8 -251 T/A Genes Associated with Urothelial Carcinoma: A Case-Control Study

Cigarette smoking and exposure to environmental tobacco smoke are well-known risk factors for urothelial carcinoma (UC). We conducted a hospital-based case-control study involving 287 UC cases and 574 cancer-free controls to investigate the joint effects of cigarette smoking and polymorphisms of inflammatory genes on UC risk. Tumor necrosis factor alpha (TNF-α) -308 G/A and interleukin-8 (IL-8) -251 T/A polymorphisms were determined using a polymerase chain reaction-restriction fragment length polymorphism method. People who had ever smoked and those who were exposed to environmental tobacco smoke had significantly increased UC odds ratios (ORs) of 1.65 and 1.68, respectively. Participants who had smoked more than 18 pack-years had a significantly increased UC OR of 2.64. People who had ever smoked and who carried the A/A genotype of the TNF-α -308 G/A polymorphism had a significantly higher UC OR (10.25) compared to people who had never smoked and who carried the G/G or G/A genotype. In addition, people who had ever smoked and who carried the IL-8 -251 T/T genotype had a significantly increased UC OR (3.08) compared to people who had never smoked and who carried the T/A or A/A genotype. In a combined analysis of three major risk factors (cumulative cigarette smoking, the TNF-α -308 A/A genotype, and the IL-8 -251 T/T genotype), subjects with any one, any two, and all three risk factors experienced significantly increased UC ORs of 1.55, 2.89, and 3.77, respectively, compared to individuals with none of the risk factors. Conclusions. Our results indicate that the combined effects of cumulative cigarette exposure and the TNF-α -308 A/A genotype and/or the IL-8 -251 T/T genotype on UC OR showed a significant dose-response relationship.

MicroRNAs in Smoking-Related Carcinogenesis: Biomarkers, Functions, and Therapy

Long-term heavy cigarette smoking is a well-known high-risk factor for carcinogenesis in various organs such as the head and neck, lungs, and urinary bladder. Furthermore, cigarette smoking can systemically accelerate aging, and as the result, promoting carcinogenesis via changing the host microenvironment. Various inflammatory factors, hormones, and chemical mediators induced by smoking mediate carcinoma-related molecules and induce carcinogenesis. MicroRNAs (miRNAs) are a family of short noncoding RNA molecules that bind to mRNAs and inhibit their expression. Cigarette smoke induces the expression of various miRNAs, many of which are known to function in the post-transcriptional silencing of anticancer molecules, thereby leading to smoking-induced carcinogenesis. Analysis of expression profiles of smoking-induced miRNAs can help identify biomarkers for the diagnosis and prognosis of smoking-related cancers and prediction of therapeutic responses, as well as revealing promising therapeutic targets. Here, we introduce the most recent and useful findings of miRNA analyses focused on lung cancer and urinary bladder cancer, which are strongly associated with cigarette smoking, and discuss the utility of miRNAs as clinical biomarkers.

Excision Repair Cross-complementation Group 1 is a Prognostic Biomarker in Patients with Colorectal Cancer Receiving Chemotherapy

Background:

Conflicting results about the association between expression level of excision repair cross-complementation group 1 (ERCC1) and clinical outcome in patients with colorectal cancer (CRC) receiving chemotherapy have been reported. Thus, we searched the available articles and performed the meta-analysis to elucidate the prognostic role of ERCC1 expression in patients with CRC.

Methods:

A thorough literature search using PubMed (Medline), Embase, Cochrane Library, Web of Science databases, and Chinese Science Citation Database was conducted to obtain the relevant studies. Pooled hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to estimate the results.

Results:

A total of 11 studies were finally enrolled in this meta-analysis. Compared with patients with lower ERCC1 expression, patients with higher ERCC1 expression tended to have unfavorable overall survival (OS) (HR = 2.325, 95% CI: 1.720–3.143, P < 0.001), progression-free survival (PFS) (HR = 1.917, 95% CI: 1.366–2.691, P < 0.001) and poor response to chemotherapy (OR = 0.491, 95% CI: 0.243–0.990, P = 0.047). Subgroup analyses by treatment setting, ethnicity, HR extraction, detection methods, survival analysis, and study design demonstrated that our results were robust.

Conclusions:

ERCC1 expression may be taken as an effective prognostic factor predicting the response to chemotherapy, OS, and PFS. Further studies with better study design and longer follow-up are warranted in order to gain a deeper understanding of ERCC1's prognostic value.

MicroRNA-20b inhibits the proliferation, migration and invasion of bladder cancer EJ cells via the targeting of cell cycle regulation and Sp-1-mediated MMP-2 expression

MicroRNAs (miRs) serve either as oncogenes or tumor-suppressor genes in tumor progression. MicroRNA-20b (miR‑20b) is known to be involved with the oncomirs of several types of cancers. However, in the present study we describe how miR-20b inhibits the proliferation, migration and invasion of bladder cancer EJ cells. In the present study, miR-20b was downregulated in bladder cancer cell lines, and its overexpression resulted in a significant reduction in the proliferation of EJ cells. In addition, via a bioinformatics approach, we identified cell cycle-regulated genes that are the putative targets of miR-20b. The transfection of miR-20b into EJ cells induced G1 phase cell cycle arrest via the decreased expression of cyclin D1, CDK2 and CDK6 without affecting another G1 phase cell cycle regulator, cyclin E. The cell cycle inhibitor p21WAF1 was upregulated in the miR-20b transfected cells. Moreover, the enforced expression of miR-20b resulted in impaired wound-healing migration and invasion in the EJ cells. Based on our target prediction analysis of miRs, we confirmed that miR-20b overexpression strongly impedes MMP-2 expression via suppressive activation of the Sp-1 binding motif, an important transcription factor present in the MMP-2 promoter. Herein, we report the novel concept that miR-20b exerts a suppressive effect on both cell cycle-modulated proliferation and MMP-2-mediated migration and invasion in bladder cancer EJ cells.

Smoking-induced immune deviation contributes to progression of bladder and other cancers

We propose here that cigarette smoke (CS), in addition to its established genotoxic effects, elicits chronic albeit sub-clinical immune suppression, which is a major contributor to cancer progression. This hypothesis, presented here primarily in the context of bladder cancers (BCs), is applicable to other cancers, including those without a confirmed link to smoking.

Biomarkers of polycyclic aromatic hydrocarbon exposure in European coke oven workers

Biomonitoring is an excellent method for capturing the results of all exposures, regardless of route. Coke oven workers include certain groups that have the potential for high exposure to polycyclic aromatic hydrocarbons (PAH) and other materials. Biomarkers of exposure to these agents include PAH metabolites as markers of internal dose and carcinogen-DNA adducts as measure of effective dose. The purpose of this study was to determine the levels of these biomarkers in persons with different job duties in a modern coke oven plant. We report that the mean levels of 1-hydroxypyrene (1HP) and carcinogen DNA adducts in the exfoliated urothelial cells of coke oven workers are increased the closer a group of workers is to the ovens and highest in the top oven workers with average 1HP level of 11.6 μg/l and 22 adducts per 10(9) unadducted nucleotides. Both 1HP and carcinogen DNA adduct levels increased in supervisors, area workers, side oven workers, top and side oven workers, and top oven workers, respectively. These data are the first to demonstrate an increase in target organ genotoxicity in coke oven workers and a relationship with other biomarkers. Future studies will determine the identity of the DNA adducts, their correlation with 1HP levels and the relationship between levels in individual workers.

Human DNA damage by the synergistic action of 4-aminobiphenyl and nitric oxide: an immunochemical study

4-Aminobiphenyl (4-ABP), an aromatic amine is a major environmental carcinogen found mainly in cigarette smoke. It has been vastly implicated in mutagenesis and cancer development. In this study, commercially available human placental DNA was exposed to 4-ABP (1.3 mM) in presence of sodium nitroprusside (SNP; 8 mM) at 37°C for 3 h. The 4-ABP + SNP-mediated structural changes in human DNA were studied by ultraviolet, circular dichroism and fluorescence spectroscopy, thermal melting profile, agarose gel electrophoresis, and nuclease S1 digestibility assay. Spectroscopical analysis and melting temperature studies suggest structural perturbations in the DNA as a result of modification. This might be due to generation of single-stranded regions and destabilization of hydrogen bonds. Modification was also visualized in agarose gel electrophoresis. Furthermore, nuclease S1 digestibility confirmed the generation of single strand breaks. Rabbits challenged with 4-ABP-SNP-modified human DNA-induced high-titer immunogen-specific antibodies, which showed Cross-reaction with modified/unmodified DNA bases and ss-DNA in competitive inhibition assay. The immunogen specificity of induced antibodies against 4-ABP-SNP-modified human DNA was further confirmed in gel retardation assay. It may be concluded that induction of anti-modified DNA antibodies could be due to perturbation in the DNA structure and its subsequent recognition by immunoregulatory cells as a foreign molecule.

Comprehensive analyses of DNA repair pathways, smoking and bladder cancer risk in Los Angeles and Shanghai

Tobacco smoking is a bladder cancer risk factor and a source of carcinogens that induce DNA damage to urothelial cells. Using data and samples from 988 cases and 1,004 controls enrolled in the Los Angeles County Bladder Cancer Study and the Shanghai Bladder Cancer Study, we investigated associations between bladder cancer risk and 632 tagSNPs that comprehensively capture genetic variation in 28 DNA repair genes from four DNA repair pathways: base excision repair (BER), nucleotide excision repair (NER), non-homologous end-joining (NHEJ) and homologous recombination repair (HHR). Odds ratios (ORs) and 95% confidence intervals (CIs) for each tagSNP were corrected for multiple testing for all SNPs within each gene using pACT and for genes within each pathway and across pathways with Bonferroni. Gene and pathway summary estimates were obtained using ARTP. We observed an association between bladder cancer and POLB rs7832529 (BER) (pACT = 0.003; ppathway = 0.021) among all, and SNPs in XPC (NER) and OGG1 (BER) among Chinese men and women, respectively. The NER pathway showed an overall association with risk among Chinese males (ARTP NER p = 0.034). The XRCC6 SNP rs2284082 (NHEJ), also in LD with SREBF2, showed an interaction with smoking (smoking status interaction pgene = 0.001, ppathway = 0.008, poverall = 0.034). Our findings support a role in bladder carcinogenesis for regions that map close to or within BER (POLB, OGG1) and NER genes (XPC). A SNP that tags both the XRCC6 and SREBF2 genes strongly modifies the association between bladder cancer risk and smoking.

Association between CCND1 and XPC polymorphisms and bladder cancer risk: a meta-analysis based on 15 case-control studies

Perturbations in cell cycle and DNA repair genes might affect susceptibility to cancer. The aim of this meta-analysis is to generate large-scale evidence to determine the degree to which common Cyclin D1 (CCND1) G870A (dbSNP: rs603965) and xeroderma pigmentosum group C (XPC) Ala499Val (dbSNP: rs2228000) polymorphisms are associated with susceptibility to bladder cancer. The electronic databases PubMed, Embase, Web of Science, and CNKI were searched for relevant studies (with an upper date limit of July 25, 2013). The principal outcome measure for evaluating the strength of association was crude odds ratios (ORs) along with their corresponding confidence intervals (95%CIs). We found and reviewed nine case-control studies on CCND1 G870A with a total of 6,823 subjects and seven studies on XPC Ala499Val with a total of 7,674 subjects. Our meta-analysis provides evidence that the variant genotype of CCND1 G870A showed a significant association in the occurrence of invasive bladder tumors in former and current smokers. The XPC Ala499Val polymorphism correlated with significant differences between patients and unaffected subjects, but when the groups were stratified by ethnicity, the magnitude of the overall effect was similar only among Caucasian populations. Results from our meta-analysis support the view that the G870A polymorphism may modulate the risk of bladder cancer in conjunction with tobacco smoking and that the Ala499Val polymorphism may contribute to the susceptibility to bladder cancer in Caucasian populations. Our findings, however, warrant larger well-designed studies to investigate the significance of these two polymorphisms as markers of susceptibility to bladder cancer.

Genetic variant in APE1 gene promoter contributes to cervical cancer risk

OBJECTIVE

Apurinic/apyrimidinic endonuclease 1 (APE1) is an essential enzyme in the base excision repair pathway, which plays an important role in repairing DNA damage caused by oxidation and alkylation. However, the exact mechanism of APE1 associated with cervical cancer risk is still unknown. In this study, we explored whether the APE1 -656T>G polymorphism contributed to the risk of cervical cancer.

STUDY DESIGN

In the hospital-based case-control study, 306 cervical cancer cases and 306 cancer-free controls were genotyped for the APE1 -656T>G polymorphism using the polymerase chain reaction restriction fragment length polymorphism method. Luciferase reporter assay and electrophoretic mobility shift assay were used to evaluate the APE1 transcriptional activity and the binding ability of transcriptional factors to the APE1 promoter, respectively.

RESULTS

Logistic regression analysis showed that individuals with the APE1 -656 TG/GG genotypes had a significantly reduced risk of cervical cancer compared with the TT genotype (adjusted odds ratio, 0.61; 95% confidence interval, 0.42-0.89). The luciferase assays in 3 cell lines showed that the APE1 -656T>G substitution can increase the expression of APE1, which was consistent with the finding of association study. Electrophoretic mobility shift assay further indicated that the APE1 -656T>G polymorphism enhanced the binding affinity of transcriptional factors to the promoter region.

CONCLUSION

These findings suggested that the APE1 -656T>G polymorphism was associated with cervical cancer risk in a Chinese population by affecting the binding affinity of transcriptional factors to the promoter, leading to an increased expression level of APE1.

Urinary biomarkers of smokers' exposure to tobacco smoke constituents in tobacco products assessment: a fit for purpose approach

There are established guidelines for bioanalytical assay validation and qualification of biomarkers. In this review, they were applied to a panel of urinary biomarkers of tobacco smoke exposure as part of a "fit for purpose" approach to the assessment of smoke constituents exposure in groups of tobacco product smokers. Clinical studies have allowed the identification of a group of tobacco exposure biomarkers demonstrating a good doseresponse relationship whilst others such as dihydroxybutyl mercapturic acid and 2-carboxy-1-methylethylmercapturic acid - did not reproducibly discriminate smokers and non-smokers. Furthermore, there are currently no agreed common reference standards to measure absolute concentrations and few inter-laboratory trials have been performed to establish consensus values for interim standards. Thus, we also discuss in this review additional requirements for the generation of robust data on urinary biomarkers, including toxicant metabolism and disposition, method validation and qualification for use in tobacco products comparison studies.

BRCA1 and ERCC1 mRNA levels are associated with lymph node metastasis in Chinese patients with colorectal cancer

BACKGROUND

Although both excision repair cross-complementing group 1 (ERCC1) and breast cancer susceptibility gene 1 (BRCA1) can be effective biomarkers for chemosensitivity in primary malignant tumors, their applicability to metastases is poorly understood. Here, ERCC1 and BRCA1, which are linked to lymph node metastasis (LNM) in colorectal cancer (CRC), were evaluated in primary CRC samples from Chinese patients with LNM (LNM CRC) or without LNM (non-LNM CRC). mRNA levels of ERCC1 and BRCA1 in CRC samples, and their relationships to primary CRC and LNM, were also examined.

METHODS

Differences in BRCA1 and ERCC1 gene expression between primary CRC with or without LNM were assessed in CRC samples from 120 Chinese patients, using real-time polymerase chain reaction. Relationships between ERCC1 and BRCA1 expression and clinicopathological parameters and prognoses were also examined.

RESULTS

ERCC1 and BRCA1 were significantly down-regulated in LNM CRC compared with non-LNM CRC. Down-expression of ERCC1 and BRCA1 was significantly associated with LNM (P < 0.001), advanced TNM stage (P < 0.001), and decreased 5-year overall survival rate (P < 0.001). Univariate and multivariate analyses showed ERCC1 and BRCA1 expression as independent predictors of recurrence and survival in CRC patients (P < 0.05).

CONCLUSIONS

ERCC1 and BRCA1 mRNA expression levels correlate inversely to CRC metastasis. ERCC1 and BRCA1 might serve as biomarkers for LNM and as prognostic indicators for CRC; their down-expressions are predictors of poor outcome in CRC patients.

Polycyclic aromatic hydrocarbons and esophageal squamous cell carcinoma

Esophageal cancer (EC) is the 8th most common cancer and the 6th most frequent cause of cancer mortality worldwide. Esophageal squamous cell carcinoma (ESCC) is the most common type of EC. Exposure to polycyclic aromatic hydrocarbons (PAHs) has been suggested as a risk factor for developing ESCC. In this paper we will review different aspects of the relationship between PAH exposure and ESCC. PAHs are a group of compounds that are formed by incomplete combustion of organic matter. Studies in humans have shown an association between PAH exposure and development of ESCC in many populations. The results of a recent case-control study in a high risk population in northeastern Iran showed a dramatic dose-response relationship between PAH content in non-tumor esophageal tissue (the target tissue for esophageal carcinogenesis) and ESCC case status, consistent with a causal role for PAH exposure in the pathogenesis of ESCC.  Identifying the main sources of exposure to PAHs may be the first and most important step in designing appropriate PAH-reduction interventions for controlling ESCC, especially in high risk areas. Coal smoke and drinking mate have been suggested as important modifiable sources of PAH exposure in China and Brazil, respectively. But the primary source of exposure to PAHs in other high risk areas for ESCC, such as northeastern Iran, has not yet been identified. Thus, environmental studies to determining important sources of PAH exposure should be considered as a high priority in future research projects in these areas.

An association between XPC Lys939Gln polymorphism and the risk of bladder cancer: a meta-analysis

The polymorphism Lys939Gln in xeroderma pigmentosum complementation group C (XPC) gene has been reported to be associated with bladder cancer in some studies, though the results remain inconclusive. To explore this relationship between XPC Lys939Gln polymorphism and the susceptibility for bladder cancer and the impact of smoking exposures, a cumulative meta-analysis was performed in this study. PubMed and EMBASE databases have been systematically searched to identify relevant studies. Data were abstracted independently by two reviewers. A meta-analysis was performed to examine the association between XPC Lys939Gln polymorphism and susceptibility to bladder cancer (BC). Odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated. Thirteen studies were chosen in this meta-analysis, involving 4,927 BC cases (1,119 Asian, 2,670 Caucasian, and 1,138 mixed) and 5,185 controls (1,399 Asian, 2,629 Caucasian, and 1,157 mixed). The XPC 939Gln allele was significantly associated with increased risk of BC based on allelic contrast (OR = 1.11, 95 % CI = 1.02-1.21), homozygote comparison (OR = 1.35, 95 % CI = 1.08-1.68), and a recessive genetic model (OR = 1.36, 95 % CI = 1.09-1.68). The results from the present meta-analysis indicated that the 939Gln polymorphism in XPC is a risk factor for bladder carcinogenesis. Further large and well-designed studies are needed to confirm this conclusion.

Polymorphism of the DNA repair genes RAD51 and XRCC2 in smoking- and drinking-related laryngeal cancer in a Polish population

INTRODUCTION

Cigarette smoke and alcohol can generate reactive oxygen species, which may induce DNA double-strand breaks (DSBs), the most serious DNA lesion. In humans, DSBs are repaired mainly by non-homologous end joining and homologous recombination repair (HRR). Several polymorphisms in the DNA repair gene have been extensively studied in the association with various human cancers. In the present work we investigated the association between polymorphisms of two HRR genes, XRCC2 and RAD51, and tobacco- and alcohol-related larynx cancer in a Polish population.

MATERIAL AND METHODS

Two polymorphisms of the XRCC2 gene, -41657C > T (rs718282) and 31479G > A (rs3218536), as well as one polymorphism of the RAD51 gene, -135G > C (rs1801320), were investigated by PCR-RFLP in 253 patients with larynx cancer and 253 age- and sex-matched non-cancer controls.

RESULTS

Analysis of the gene-smoking and -drinking interactions revealed a weak association between larynx cancer and the -41657C > T polymorphisms of the XRCC2 gene among the moderate alcohol drinkers. The C allele of the -135G > C polymorphism of RAD51 increased cancer risk in the smoker group. Increased risk was also found for heavy drinkers. Additionally, there were no significant differences between distributions of genotypes in subgroups assigned to different TNM stages and grades.

CONCLUSIONS

The results indicated that the -135G > C polymorphism of the RAD51 gene may be associated with smoking- and drinking-related larynx cancer in Poland.

An association between hOGG1 Ser326Cys polymorphism and the risk of bladder cancer in non-smokers: a meta-analysis

Background

Bladder cancer results from complex interactions between many genetic and environment factors. The polymorphism Ser326Cys in hOGG1 gene has been reported to be associated with bladder cancer in some studies, though the results remain inconclusive. To explore this relationship of hOGG1 polymorphism and the susceptibility for bladder cancer and the impact of smoking exposures, a cumulative meta-analysis was performed in this study.

Methods

We extracted the data from the Pubmed database up to January 9, 2012 using the search phrases “hOGG1, Ser326Cys polymorphism and bladder cancer”. Seven case–control studies were identified, including 2474 patients and 2408 controls. Four of them provided the analysis of smoking effects, with 1372 smokers and 947 non-smokers. The odds ratios (ORs) and associated 95 % confidence intervals (CIs) were calculated using fixed- or random- effects models.

Results

Regarding the overall association between the hOGG1 326Cys allele and bladder cancer risk, the meta-analysis did not reveal a significant effect in the additive model (OR: 1.06, 95 % CI: 0.96-1.26; p = 0.49), the recessive genetic model (OR: 1.05, 95 % CI: 0.65-1.70; p = 0.85) or the dominant genetic model (OR: 1.07, 95 % CI: 0.87-1.32; p = 0.53). Similarly, no significant relationship was observed in the stratified analysis by ethnicity, study design and Hardy-Weinberg equilibrium (all p > 0.05). In the non-smokers, however, hOGG1 326Cys allele significantly increased the risk for bladder cancer and the ORs in the additive model, homozygote contrast and recessive genetic model were 1.59 (p = 0.02), 2.53(p = 0.003) and 2.41(p = 0.0005), respectively. Nevertheless, in the smoker subgroup, similar findings could not be found in all genetic models (all p > 0.05).

Conclusions

The association between the hOGG1 326Cys allele and bladder cancer was significant in non-smoker population, while was non-detectable in common or smoker populations. This meta-analysis suggests that the hOGG1 Ser326Cys polymorphism may be a risk factor for bladder cancer without exposure to smoking. Further functional studies are needed to elucidate the gene polymorphism-bladder cancer relationship and gene-environment interactions.

Exposure to Polycyclic Aromatic Hydrocarbons Among Never Smokers in Golestan Province, Iran, an Area of High Incidence of Esophageal Cancer - a Cross-Sectional Study with Repeated Measurement of Urinary 1-OHPG in Two Seasons

Studies have suggested a possible role of polycyclic aromatic hydrocarbons (PAHs) in the etiology of esophageal cancer in Golestan Province, Iran, where incidence of this cancer is very high. In order to investigate the patterns of non-smoking related exposure to PAHs in Golestan, we conducted a cross-sectional study collecting questionnaire data, genotyping polymorphisms related to PAH metabolism, and measuring levels of 1-hydroxypyrene glucuronide (1-OHPG), a PAH metabolite, in urine samples collected in two seasons from the same group of 111 randomly selected never-smoking women. Beta-coefficients for correlations between 1-OHPG as dependent variable and other variables were calculated using linear regression models. The creatinine-adjusted 1-OHPG levels in both winter and summer samples were approximately 110 μmol/molCr (P for seasonal difference = 0.40). In winter, red meat intake (β = 0.208; P = 0.03), processed meat intake (β = 0.218; P = 0.02), and GSTT1-02 polymorphism ("null" genotype: β = 0.228; P = 0.02) showed associations with 1-OHPG levels, while CYP1B1-07 polymorphism (GG versus AA + GA genotypes: β = -0.256; P = 0.008) showed an inverse association. In summer, making bread at home (> weekly versus never: β = 0.203; P = 0.04), second-hand smoke (exposure to ≥3 cigarettes versus no exposure: β = 0.254; P = 0.01), and GSTM1-02 "null" genotype (β = 0.198; P = 0.04) showed associations with 1-OHPG levels, but GSTP1-02 polymorphism (CT + TT versus CC: β = -0.218; P = 0.03) showed an inverse association. This study confirms high exposure of the general population in Golestan to PAHs and suggests that certain foods, cooking methods, and genetic polymorphisms increase exposure to PAHs.

Selenoproteins in bladder cancer

Selenoproteins with genetically encoded selenium (Se) are very important in response to oxidative stress, redox balance and regulation of various metabolic and developmental processes. Although increased circulating Se has been associated with 33% risk reduction of bladder cancer, there are little data on selenoprotein expression at the protein and genetic level from both human and animal studies. Data from the Mammalian Gene Collection (MGC) Project clearly showed that highest mRNA expression in human urinary epithelium for TRXR1 (thioredoxin reductase 1), GPX1 (glutathione peroxidase 1), SEP15 (15 kDa selenoprotein), SELT (selenoprotein T) and SEPW1 (selenoprotein W1). Although bladder tumor has been characterized by increased Se, GPX and TRXR activity, circulating Se and GPX was interestingly decreased in these cancer patients. As such, selenoprotein expression in urinary epithelium may be involved in bladder cancer (development, progression and recurrence) and may play a significant role in chemotherapeutic intervention. Despite these findings, the role of selenoproteins in bladder cancer has rarely been investigated and the significance of selenoproteins in normal and malignant uroepithelium remains poorly understood.

A Review of ERCC1 Gene in Bladder Cancer: Implications for Carcinogenesis and Resistance to Chemoradiotherapy

The excision repair cross-complementing group 1 (ERCC1) gene performs a critical incision step in DNA repair and is reported to be correlated with carcinogenesis and resistance to drug or ionizing radiation therapy. We reviewed the correlation between ERCC1 and bladder cancer. In carcinogenesis, several reports discussed the relation between ERCC1 single nucleotide polymorphisms and carcinogenesis in bladder cancer only in case-control studies. Regarding the relation between ERCC1 and resistance to chemoradiotherapy, in vitro and clinical studies indicate that ERCC1 might be related to resistance to radiation therapy rather than cisplatin therapy. It is controversial whether ERCC1 predicts prognosis of bladder cancer treated with cisplatin-based chemotherapy. Tyrosine kinase receptors or endothelial-mesenchymal transition are reported to regulate the expression of ERCC1, and further study is needed to clarify the mechanism of ERCC1 expression and resistance to chemoradiotherapy in vitro and to discover novel therapies for advanced and metastatic bladder cancer.

Genetic polymorphisms in the DNA repair genes XPD and XRCC1, p53 gene mutations and bladder cancer risk

Previous studies have suggested that certain genetic polymorphisms, specifically the Xeroderma pigmentosum group D (XPD) gene codon 751 and the X-ray repair cross-complementing group 1 (XRCC1) gene codon 399 polymorphisms, were associated with an increased risk of lung cancer, and, in some studies, with a greater risk for mutations in the p53 tumor suppressor gene in lung tumors. To evaluate whether these gene polymorphisms may be associated with an increased risk for bladder cancer or in association with p53 mutation status in bladder tumors, we screened for polymorphisms at XPD codons 751 and XRCC1 codon 399 in DNA isolated from blood of 194 bladder cancer patients and 313 healthy controls and for mutations in exons 4 to 8 of the p53 gene in bladder tumor DNA from 174 bladder cancer patients. There was a significantly higher prevalence of the XPD 751 Gln allele among the bladder cancer group, compared with the control group. No association was found between bladder cancer risk and the XRCC1 399 polymorphism. p53 mutations were found in 20.1% (35/174) patients. There was no difference in p53 mutation status among individuals with different genotypes. These results suggest that individuals who have the XPD 751 Gln allele may be at an increased risk for bladder cancer, although this may not lead to an increased risk for mutations in the p53 gene.

Polymorphisms in DNA repair genes XRCC1, XRCC3 and XPD, and colorectal cancer risk: a case-control study in an Indian population

PURPOSE

Genetic polymorphisms in DNA repair genes may influence variations in individual DNA repair capacity, which could be associated with the development of cancer. We detected the distributions of three single-nucleotide polymorphisms (XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln) in DNA repair genes, and assessed the associations of these genetic polymorphisms with colon and rectal cancer susceptibility as well as evaluated the interactions of gene-gene and gene-environment in a case-control study of an Indian population.

METHODS

This case-control study was conducted with 302 cases (including 59 colon and 243 rectal cancer patients) and 291 cancer-free healthy controls. Genotypes were determined by PCR-RLFP assays. The effects [odds ratios (ORs) and 95% confidence intervals (95% CIs)] of genetic polymorphisms on colorectal cancer were estimated using unconditional logistic regression.

RESULTS

The XRCC1 399Gln allele was found to be associated with a significantly increased rectal cancer risk among men (OR = 1.65, 95% CI 1.04-2.64). Whereas the XRCC3 241Met allele showed a protective tendency against rectal cancer (OR = 0.68, 95% CI 0.46-1.02) for both men and women. Furthermore, a combination of the XRCC1 399Gln allele with XRCC3 Thr/Thr genotype and the XPD 751Gln allele demonstrated the highest rectal cancer risk (OR = 3.52, 95% CI 1.43-9.44).

CONCLUSIONS

The combined effects of putative risk alleles/genotypes for different DNA repair pathways may strengthen the susceptibility to rectal cancer.

A meta-analysis on XRCC1 and XRCC3 polymorphisms and colorectal cancer risk

PURPOSE

Studies on polymorphism of X-ray repair cross-complementing group 1 (XRCC1), group 3 (XRCC3), and colorectal cancer risk are inconclusive. The purpose of this study is to evaluate the role of XRCC1 R399Q, R194W, and XRCC3 T241M genotypes in colorectal cancer susceptibility.

METHODS

We performed a meta-analysis on all available studies that provided 3,514/4,686 cases/controls for R399Q, 2,767/3,907 cases/controls for R194W and 3,183/3,926 cases/controls for T241M.

RESULTS

Overall, no apparent effects of 194 W allele compared to 194R on colorectal cancer risk were found in all subjects and subgroups (Asians and Caucasians). Insignificant effects were also found under other genetic contrasts (homologous contrast, dominant model, and recessive model). The same pattern of results was produced in T241M polymorphism. The 399Q allele compared to 399R showed no significant association with colorectal cancer risk in all subjects and subgroups. However, protective effects of 399QQ genotype were observed under recessive model (QQ/QR + RR) [P = 0.02, OR = 0.84, 95% CI (0.72, 0.97)] and homozygote contrast (QQ/RR) [P = 0.01, OR = 0.81; 95% CI (0.69, 0.95)] in all subjects.

CONCLUSION

Results suggested that 399Q allele might act as a recessive allele in its association with colorectal cancer.

An improved liquid chromatography-tandem mass spectrometry method for the quantification of 4-aminobiphenyl DNA adducts in urinary bladder cells and tissues

Exposure to 4-aminobiphenyl (4-ABP), an environmental and tobacco smoke carcinogen that targets the bladder urothelium, leads to DNA adduct formation and cancer development [1]. Two major analytical challenges in DNA adduct analysis of human samples have been limited sample availability and the need to reach detection limits approaching the part-per-billion threshold. By operating at nano-flow rates and incorporating a capillary analytical column in addition to an online sample enrichment step, we have developed a sensitive and quantitative HPLC-MS/MS method appropriate for the analysis of such samples. This assay for the deoxyguanosine adduct of 4-ABP (dG-C8-4-ABP) gave mass detection limits of 20amol in 1.25microg of DNA (5 adducts in 10(9) nucleosides) with a linear range of 70amol to 70fmol. 4-ABP-exposed human bladder cells and rat bladder tissue were analyzed in triplicate, and higher dose concentrations led to increased numbers of detected adducts. It was subsequently established that sample requirements could be further reduced to 1microg digestions and the equivalent of 250ng DNA per injection for the detection of low levels of dG-C8-4-ABP in a matrix of exfoliated human urothelial cell DNA. This method is appropriate for the characterization and quantification of DNA adducts in human samples and can lead to a greater understanding of their role in carcinogenesis and also facilitate evaluation of chemopreventive agents.

Polymorphisms in DNA repair genes, smoking, and bladder cancer risk: findings from the international consortium of bladder cancer

Tobacco smoking is the most important and well-established bladder cancer risk factor and a rich source of chemical carcinogens and reactive oxygen species that can induce damage to DNA in urothelial cells. Therefore, common variation in DNA repair genes might modify bladder cancer risk. In this study, we present results from meta-analyses and pooled analyses conducted as part of the International Consortium of Bladder Cancer. We included data on 10 single nucleotide polymorphisms corresponding to seven DNA repair genes from 13 studies. Pooled analyses and meta-analyses included 5,282 cases and 5,954 controls of non-Latino white origin. We found evidence for weak but consistent associations with ERCC2 D312N [rs1799793; per-allele odds ratio (OR), 1.10; 95% confidence interval (95% CI), 1.01-1.19; P = 0.021], NBN E185Q (rs1805794; per-allele OR, 1.09; 95% CI, 1.01-1.18; P = 0.028), and XPC A499V (rs2228000; per-allele OR, 1.10; 95% CI, 1.00-1.21; P = 0.044). The association with NBN E185Q was limited to ever smokers (interaction P = 0.002) and was strongest for the highest levels of smoking dose and smoking duration. Overall, our study provides the strongest evidence to date for a role of common variants in DNA repair genes in bladder carcinogenesis.

Opium consumption and risk of bladder cancer: A case-control analysis

OBJECTIVE

We evaluated the relationship between opium consumption and bladder cancer (BC) in a case-control study of an Iranian population.

MATERIALS AND METHODS

In a hospital-based case-control study of 179 patients with BC and 179 cancer-free controls frequency-matched by age, sex, and smoking status, we investigated the relationship between opium consumption and BC. A comprehensive epidemiologic interview was conducted on all participants to collect personal information, such as demographics and smoking status.

RESULTS

Overall, we found significant age, sex, cigarette smoking adjusted association between BC risk and opium consumption, [odds ratio (OR) = 4.60; 95% confidence interval (CI) = 3.53-6.28]. The elevated risk was more evident in older individuals (OR = 5.42; 95% CI, 4.12-7.28) than younger individuals (OR = 3.65; 95% CI, 2.76-4.76) (P = 0.01). Heavy smokers with the opium consumption exhibited a 6-fold elevated risk for BC (OR = 6.16; 95% CI, 3.34-8.32) (P = 0.0001). When stratified according to different grades of BC, a 3.4-fold increased risk was associated with the opium consumption in grade III with an OR of 3.44 (95% CI, 2.82-8.28) (P = 0.001). A similar but slightly higher risk was also seen in case of grade IV tumors (OR = 3.86; 95% CI, 2.14-10.16) (P = 0.001). Invasive bladder tumors were more common among the opiates users (OR = 2.6; 95% CI, 1.44-5.42) (P = 0.01). Cumulative risk of BC in women with opium consumption (OR = 4.10 95% CI, 3.54-5.88) (P = 0.001) was slightly less than in men (OR = 5.10 95% CI, 3.54-5.88) (P = 0.0001). Based on Pearson correlations, the risk of BC significantly correlated with opium dependence duration (r = 0.74, P = 0.001), type of opiate used (r = 0.65, P = 0.001), and simultaneous cigarette smoking (r = 0.74, P = 0.0001).

CONCLUSION

The results indicated that there is about 5-fold increase in risk of developing this cancer in the presence of opium consumption. Further research is needed to investigate the functional implications of the opium consumption in BC.

Micronuclei assessment in the urothelial cells of women using hair dyes and its modulation by genetic polymorphisms

Increases in the frequency of micronuclei (MN) in exposed cells can be used as a measure of genotoxicity. Hair dyes contain chemicals that are eliminated by urine and could be genotoxic to urothelial cells. To address this question, we evaluated whether hair dye use is associated with an increase in the frequency of MN in urothelial cells, and whether this association is modified by NAT1 (N-acetyltransferase 1), NAT2 (N-acetyltransferase 2) and GSTM1 (glutathione-S-transferase M1) genotypes. We included 92 women participating as controls in a bladder cancer case-control study in Spain. Of those, 72 had adequate number of cells to be included in the MN analysis. There were no significant differences in the mean MN frequency in women using hair dyes in the last month (9.88 MN/1000 cells), in comparison with the MN in unexposed women (9.50 MN/1000 cells). No statistically significant differences in MN frequency were observed by type of hair dye or color of the hair dye. Comparison of subjects in the highest quartile of MN frequency (> or = 12 MN/1000 cells) and those in the lowest quartile (< or = 4 MN/1000 cells) suggested an association between hair dye use and elevated MN frequency (OR 14.2 (95% CI 0.81-247.8; P=0.069)). None of the polymorphisms examined significantly modified association between hair dye use and frequency of MN. Findings of an increased frequency of MN in urothelial cells of hair dye users suggest a possible genotoxic effect of hair dye compounds and need confirmation in larger studies.

A novel variable number of tandem repeats (VNTR) polymorphism containing Sp1 binding elements in the promoter of XRCC5 is a risk factor for human bladder cancer

X-ray repair cross-complementing 5 (XRCC5) is a gene involved in repair of DNA double-strand breaks. Abnormal expression of the XRCC5 protein is associated with genomic instability and an increased incidence of cancers. In our study, a polymorphism with a variable number of tandem repeats (21-bp repeat elements at position -201 to -160 relative to the initiation of transcription) in the promoter of XRCC5 was identified. As determined with gel-shift and super-shift assays, the binding affinity of the transcription factor Sp1 to the allele with two 21-bp repeats was greater than that for the allele with one 21-bp repeat. As established with a reporter assay, plasmids containing zero or one repeat element had higher transcriptional activities than plasmids containing two repeat elements. Furthermore, fewer tandem repeats in the promoter of XRCC5 was associated with enhanced levels of the XRCC5 protein in bladder cancer patients. Although, in a case-control study, the different genotypes were not associated with the risk of bladder cancer, individuals not carrying the two tandem repeats allele had an increased risk of bladder cancer compared with those carrying the allele with two repeats. These results indicated that, at least in a population in southeastern China, this polymorphism in the promoter of XRCC5 could regulate the expression of XRCC5 and thereby contribute to susceptibility to bladder cancer.

Exposure to the tobacco smoke constituent 4-aminobiphenyl induces chromosomal instability in human cancer cells

The relationships between environmental factors and the genetic abnormalities that drive carcinogenesis are supported by experimental and epidemiologic evidence but their molecular basis has not been fully elucidated. At the genomic level, most human cancers display either chromosomal (CIN) or microsatellite (MIN) instability. The molecular mechanisms through which normal cells acquire these forms of instability are largely unknown. The arylamine 4-aminobiphenyl (4-ABP) is a tobacco smoke constituent, an environmental contaminant, and a well-established carcinogen in humans. Among others, bladder, lung, colon, and breast cancers have been associated with 4-ABP. We have investigated the effects of 4-ABP and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on genetically stable colorectal (HCT116) and bladder (RT112) cancer cells. Cells were treated with carcinogens to generate resistant clones that were then subjected to genetic analysis to assess whether they displayed either CIN or MIN. We found that 50% to 60% of cells treated with 4-ABP developed CIN but none developed MIN as confirmed by their ability to gain and lose chromosomes. In contrast, all MNNG-treated clones (12/12) developed MIN but none developed CIN as shown by the microsatellite assay. The mismatch repair protein expression analysis suggests that the acquired mechanism of MIN resistance in the HCT116 MNNG-treated cells is associated with the reduction or the complete loss of MLH1 expression. By providing a mechanistic link between exposure to a tobacco constituent and the development of CIN, our results contribute to a better understanding of the origins of genetic instability, one of the remaining unsolved problems in cancer research.

Urinary arsenic profile affects the risk of urothelial carcinoma even at low arsenic exposure

Arsenic exposure is associated with an increased risk of urothelial carcinoma (UC). To explore the association between individual risk and urinary arsenic profile in subjects without evident exposure, 177 UC cases and 313 age-matched controls were recruited between September 2002 and May 2004 for a case-control study. Urinary arsenic species including the following three categories, inorganic arsenic (As(III)+As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)), were determined with high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Arsenic methylation profile was assessed by percentages of various arsenic species in the sum of the three categories measured. The primary methylation index (PMI) was defined as the ratio between MMA(V) and inorganic arsenic. Secondary methylation index (SMI) was determined as the ratio between DMA(V) and MMA(V). Smoking is associated with a significant risk of UC in a dose-dependent manner. After multivariate adjustment, UC cases had a significantly higher sum of all the urinary species measured, higher percent MMA(V), lower percent DMA(V), higher PMI and lower SMI values compared with controls. Smoking interacts with the urinary arsenic profile in modifying the UC risk. Differential carcinogenic effects of the urinary arsenic profile, however, were seen more prominently in non-smokers than in smokers, suggesting that smoking is not the only major environmental source of arsenic contamination since the UC risk differs in non-smokers. Subjects who have an unfavorable urinary arsenic profile have an increased UC risk even at low exposure levels.

DNA repair gene polymorphisms and probability of p53 mutation in bladder cancer

We investigated if the presence of single nucleotide polymorphisms (SNPs) in the XRCC1, XRCC3, and XPD genes were associated with the type and frequency of p53 mutations in bladder cancer. Using a hospital-based case-control study we have previously reported risks for the XRCC1 codon 194, XRCC1 codon 399, XRCC3 codon 241, and XPD codon 751 SNPs 1-3. We have also previously reported mutation data for 149 cases from this study who were screened for mutations in exons 4 through 9 of the p53 gene 4. Here we investigate possible associations between the DNA repair SNPs mentioned above and the presence of p53 mutations by comparing the frequency of each genotype between p53 mutation positive and negative cases. We also considered different classes of p53 mutations, including any mutation (nonsense, missense or silent), transversions and transitions and estimated odds ratios (ORs) and 95% confidence intervals (CI) for these associations. Cases with the XRCC1 codon 399 Gln/Gln genotype were positively associated with the presence of p53 transversions (OR = 4.8; 94% CI = 0.8-30). Cases with the XPD codon 751 Gln/Gln genotype were positively associated with the presence of p53 transitions (OR = 2.8; 95% CI = 0.8-9.3), in particular G:C-A:T transitions (OR = 3.7; 95% CI = 1.1-13). Our data provide some limited support for the hypothesis that mutations in the p53 gene in bladder cancer may differ according to the presence or absence of certain DNA repair gene variants.

No association of DNA ligase-I polymorphism with the risk of lung cancer in north-Indian population

DNA ligases play an essential role in repair, replication, and recombination of DNA, and catalyzes the formation of a phosphodiester bond at a nick junction on single- and double-strand breaks. We have conducted a hospital-based case-control study to examine the role of polymorphism of DNA repair gene ligase I (LIGI) in the context of lung cancer risk for north Indian population. One hundred, fifty-one primary lung cancer cases and an equal number of matching hospital controls were collected. The LIGI polymorphism was determined by using the PCR-RFLP method. The association between polymorphisms in the LIGI gene with the risk of lung cancer was estimated by computing odds ratios (ORs) and a 95% confidence interval (CI) using a Multivariate Logistic Regression Analysis. The risk for lung cancer was not associated for individuals featuring LIGI (AC) (OR -0.8, 95% CI = 0.44-1.40) and (AA) (OR -0.8, 95% CI = 0.41-1.80) genotypes. The DNA repair gene (LIGI) may not be playing an important role in modulating the risk of lung cancer in the north Indian population.

CYP1A2 and NAT2 phenotyping and 3-aminobiphenyl and 4-aminobiphenyl hemoglobin adduct levels in smokers and non-smokers

Some aromatic amines are considered to be putative bladder carcinogens. Hemoglobin (Hb) adducts of 3-aminobiphenyl (3-ABP) and 4-aminobiphenyl (4-ABP) have been used as biomarkers of exposure to aromatic amines from cigarette smoke. One of the goals of this study was to determine intra- and inter-individual variability in 3-ABP and 4-ABP Hb adducts and to explore the predictability of ABP Hb adduct levels based on caffeine phenotyping. The study was conducted in adult smokers (S, n = 65) and non-smokers (NS, n = 65). The subjects were phenotyped for CYP1A2 and NAT2 using urinary caffeine metabolites. Blood samples were collected twice within 6 weeks and adducts measured by GC/MS. The levels of 4-ABP Hb adducts were significantly (p < 0.0001) greater in S (34.5 +/- 21.06 pg/g Hb) compared to NS (6.3 +/- 3.02 pg/g Hb). The levels of 3-ABP Hb adducts were below the limit of quantification (BLOQ) in most (82%) of the NS and about 10-fold lower in S (3.6 +/- 3.29 pg/g Hb) compared to 4-ABP Hb adducts. No differences were observed in the adduct levels between weeks 1 and 6 in the smokers, suggesting that a single sample would be adequate to monitor cigarette smoke exposure. The regression model developed with CYP1A2, NAT2 phenotype and number of cigarettes smoked (NCIG) accounted for 47% of the variability in 3-ABP adducts, whereas 32% variability in 4-ABP adducts was accounted by CYP1A2 and NCIG. The ratio of 4-ABP Hb adducts in adult S:NS was approximately 5:1, whereas 3-ABP Hb adducts levels were BLOQ in some S, exhibited large interindividual variability ( approximately 91% compared to 57% for 4-ABP Hb) and poor dose response relationship. Therefore, 4-ABP Hb adduct levels may be a more useful biomarker of aminobiphenyl exposure from cigarette smoke.

Experimental models of human bladder carcinogenesis

Bladder cancer is the fifth most common cancer in the UK, yet human bladder carcinogenesis remains poorly understood and the response of bladder tumours to radio- and chemo-therapy is unpredictable. The aims of this article are to review human bladder carcinogenesis and appraise the different in vitro and in vivo approaches that have been developed to study the process. The review considers how in vitro models based on normal human urothelial (NHU) cells can be applied to human bladder cancer research. We conclude that recent advances in NHU cell culture offer novel approaches for defining urothelial tissue-specific responses to genotoxic and non-genotoxic carcinogens and elucidating the role of specific genes involved in the mechanisms of bladder carcinogenesis and malignant progression.

MS-920: DNA repair gene polymorphisms, diet and colorectal cancer risk in Taiwan

This hospital-based case-control study examined whether polymorphic DNA repair genes: XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln, play a role in the susceptibility to colorectal cancer. We genotyped these polymorphisms for 727 newly diagnosed colorectal adenocarcinoma cases and 736 age and sex matched healthy controls in Taiwan. Although the colorectal cancer risk was not significantly associated with these genes, the risk was significantly elevated in younger subjects (< or =60 years) with the XRCC1 399Arg/Arg genotype compared to those with XRCC1 399Gln allele (OR=1.46, 95% CI=1.06-2.99, P=0.02). The stratified analysis showed that XRCC3 interacted with meat consumption (P for interaction=0.02), but was limited to the low meat consumption (OR=2.34, 95% CI=1.28-4.29). Our results suggest that the XRCC1 Arg399Gln polymorphism may contribute to the risk of early-onset colorectal cancer and the XRCC3 Thr241Met polymorphism may modify the risk for meat-associated colorectal cancer.