Role of NQO1C609T and EPHX1 gene polymorphisms in the association of smoking and alcohol with sporadic distal colorectal adenomas: results from the UKFSS Study

Association of Activity Altering Genotypes - Tyr113His and His139Arg in Microsomal Epoxide Hydrolase Enzyme with Esophageal Squamous Cell Carcinoma

The study aimed to explore the relationship of microsomal epoxide hydrolase (mEH) exon 3 (Tyr113His) and exon 4 (His139Arg) polymorphisms and predicted mEH activity with esophageal squamous cell carcinoma (ESCC) risk. 482 histologically confirmed cases and equal number of matched controls were analyzed by polymerase chain reaction-restriction length polymorphism (PCR-RFLP). Conditional logistic regression models were used to examine the association of polymorphisms with ESCC. We noted exon 3 slow genotype (OR = 6.57; CI 3.43-12.57) as well as predicted low mEH activity (OR = 3.99; CI 2.32-6.85) was associated with the ESCC risk. Elevated ESCC risk estimates were seen in smokers independent of genotypes but the association was stronger among smokers with exon 3 variant (OR = 6.67; 3.29-13.53) and low activity (OR = 7.52; CI 3.46-16.37) genotypes. Positive family history of cancer synergistically increased ESCC risk in the individuals who harbored exon 3 (OR = 13.59; CI 5.63-32.81) or altered mEH activity genotypes (OR = 13.35; CI 5.10-34.94). Significant interaction was seen between mEH exon 3 and exon 4 genotypes (P = 0.006) and between predicted mEH activity and positive family history of cancer (P = 0.018). These findings suggest association of ESCC risk with mEH polymorphisms which get modified by tobacco smoking and positive family history of cancer.

Effects of interactions between common genetic variants and alcohol consumption on colorectal cancer risk

BACKGROUND

Genome-wide association studies (GWAS) have identified approximately 40 common genetic loci associated with colorectal cancer risk. To investigate possible gene-environment interactions (GEIs) between GWAS-identified single-nucleotide polymorphisms (SNPs) and alcohol consumption with respect to colorectal cancer, a hospital-based case-control study was conducted.

RESULTS

Higher levels of alcohol consumption as calculated based on a standardized definition of a drink (1 drink=12.5g of ethanol) were associated with increased risk of colorectal cancer (OR=2.47, 95% CI=1.62-3.76 for heavy drinkers [>50g/day] compared to never drinkers; ptrend<0.01). SNP rs6687758 near the DUSP10 gene at 1q41 had a statistically significant interaction with alcohol consumption in analyses of standardized drinks (p=4.6×10-3), although this did not surpass the corrected threshold for multiple testing. When stratified by alcohol consumption levels, in an additive model the risk of colorectal cancer associated with the G allele of rs6687758 tended to increase among individuals in the heavier alcohol consumption strata. A statistically significant association between rs6687758 and colorectal cancer risk was observed among moderate alcohol drinkers who consumed between >12.5 and ≤50g of alcohol per day (OR=1.46, 95% CI=1.01-2.11).

METHODS

A total of 2,109 subjects (703 colorectal cancer patients and 1,406 healthy controls) were recruited from the Korean National Cancer Center. For genotyping, 30 GWAS-identified SNPs were selected. A logistic regression model was used to evaluate associations of SNPs and alcohol consumption with colorectal cancer risk. We also tested GEIs between SNPs and alcohol consumption using a logistic model with multiplicative interaction terms.

CONCLUSIONS

Our results suggest that SNP rs6687758 at 1q41 may interact with alcohol consumption in the etiology of colorectal cancer.

CYP1A1, CYP2E1 and EPHX1 polymorphisms in sporadic colorectal neoplasms

AIM

To investigate the contribution of polymorphisms in the CYP1A1, CYP2E1 and EPHX1 genes on sporadic colorectal cancer (SCRC) risk.

METHODS

Six hundred forty-one individuals (227 patients with SCRC and 400 controls) were enrolled in the study. The variables analyzed were age, gender, tobacco and alcohol consumption, and clinical and histopathological tumor parameters. The CYP1A1*2A, CYP1A1*2C CYP2E1*5B and CYP2E1*6 polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The EPHX1 Tyr113His, EPHX1 His139Arg and CYP1A1*2C polymorphisms were detected by real-time PCR. Chi-squared test and binary logistic regression were used in the statistical analysis. Haplotype analysis was conducted using the Haploview program, version 2.05.

RESULTS

Age over 62 years was a risk factor for SCRC development (OR = 7.54, 95%CI: 4.94-11.50, P < 0.01). Male individuals were less susceptible to SCRC (OR = 0.55, 95%CI: 0.35-0.85, P < 0.01). The CYP2E1*5B polymorphism was associated with SCRC in the codominant (heterozygous genotype: OR = 2.66, 95%CI: 1.64-4.32, P < 0.01), dominant (OR = 2.82, 95%CI: 1.74-4.55, P < 0.01), overdominant (OR = 2.58, 95%CI: 1.59-4.19, P < 0.01), and log-additive models (OR = 2.84, 95%CI: 1.78-4.52, P < 0.01). The CYP2E1*6 polymorphism was associated with an increased SCRC risk in codominant (heterozygous genotype: OR = 2.81, 95%CI: 1.84-4.28, P < 0.01; homozygous polymorphic: OR = 7.32, 95%CI: 1.85-28.96, P < 0.01), dominant (OR = 2.97, 95%CI: 1.97-4.50, P < 0.01), recessive (OR = 5.26, 95%CI: 1.35-20.50, P = 0.016), overdominant (OR = 2.64, 95%CI: 1.74-4.01, P < 0.01), and log-additive models (OR = 2.78, 95%CI: 1.91-4.06, P < 0.01). The haplotype formed by the minor alleles of the CYP2E1*5B (C) and CYP2E1*6 (A) polymorphisms was associated with SCRC (P = 0.002). However, the CYP1A1*2A, CYP1A1*2C, EPHX1 Tyr113His and EPHX1 His139Arg polymorphisms were not associated with SCRC.

CONCLUSION

In conclusion, the results demonstrated that CYP2E1*5B and CYP2E1*6 minor alleles play a role in the development of SCRC.

Microsomal epoxide hydrolase 1 (EPHX1): Gene, structure, function, and role in human disease

Microsomal epoxide hydrolase (EPHX1) is an evolutionarily highly conserved biotransformation enzyme for converting epoxides to diols. Notably, the enzyme is able to either detoxify or bioactivate a wide range of substrates. Mutations and polymorphic variants in the EPHX1 gene have been associated with susceptibility to several human diseases including cancer. This review summarizes the key knowledge concerning EPHX1 gene and protein structure, expression pattern and regulation, and substrate specificity. The relevance of EPHX1 for human pathology is especially discussed.

NQO1 C609T polymorphism and colorectal cancer susceptibility: a meta-analysis

INTRODUCTION

A FEW STUDIES HAVE REPORTED AN ASSOCIATION BETWEEN NADP(H): quinine oxidoreductase 1 (NQO1) C609T polymorphism and susceptibility to colorectal cancer (CRC). However, the results were inconsistent rather than conclusive. We performed a meta-analysis to examine this association in various populations.

MATERIAL AND METHODS

Eligible articles were identified by a search of several databases up until June 30, 2013. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of the association.

RESULTS

Overall, 14 case-control studies with 4,461 cases and 5,474 controls were included in this meta-analysis. The results indicated that the NQO1 C609T polymorphism was significantly associated with CRC susceptibility (summary ORs (95% CIs): 1.30 (1.07-1.59) for CT vs. CC, 1.64 (1.15-2.33) for TT vs. CC, 1.34 (1.10-1.64) for TT/CT vs. CC, and 1.43 (1.10-1.87) for TT vs. CT/CC). Subgroup analyses indicated that the T allele was significantly associated with CRC susceptibility in both Asians and Caucasians, and was also observed in high quality studies and hospital-based case-control studies. Specifically, we found a positive association between the NQO1 C609T polymorphism and CRC susceptibility in smokers, but not in non-smokers.

CONCLUSIONS

The results of this meta-analysis suggest that the NQO1 C609T polymorphism significantly contributes to increased susceptibility to CRC in both Asians and Caucasians.

NQO1 609C>T polymorphism interaction with tobacco smoking and alcohol drinking increases colorectal cancer risk in a Chinese population

BACKGROUND

NAD (P)H:quinone oxidoreductase (NQO1) catalyzes the activation of some environmental procarcinogens present in tobacco smoke or the diet. We conducted a hospital-based case-control study to evaluate the potential association between NQO1 609C>T polymorphisms and colorectal cancer risk in a Chinese population.

METHODS

The study population comprised 672 histologically confirmed colorectal cancer patients and 672 frequency-matched control subjects without cancer or systemic illness. We used PCR restriction fragment length polymorphism-based methods for genotyping analyses and unconditional logistic regression model for statistical evaluations.

RESULTS

The risk of colorectal cancer increased with the level of smoking and decreased with the consumption of tea, fresh fruits, and vegetables. In addition, we found that the NQO1 609 CT and TT genotypes were associated with an increased risk of colorectal cancer (CT: adjusted OR=2.02, 95% CI=1.55-2.57; TT: adjusted OR=2.51, 95% CI=1.82-3.47), compared with the CC genotype. Moreover, NQO1 609C>T appeared to have a multiplicative joint effect with both tobacco smoking and alcoholic drinking (P for multiplicative interactions were 0.0001 and 0.013, respectively) on colorectal cancer risk.

CONCLUSION

Our findings suggest that the NQO1 609C>T polymorphism plays an important role in the development of colorectal cancer in the Chinese population, which is strengthened by alcohol drinking or tobacco smoking.

EPHX1 gene polymorphisms in alcohol dependence and their distribution among the Indian populations

BACKGROUND

The microsomal epoxide hydrolase is a phase II enzyme of the biotransformation. The human epoxide hydrolase 1 (EPHX1) gene lies in the chromosomal region 1q42.1 and exhibits polymorphism. Two single nucleotide polymorphisms (SNPs) have been described in the coding region of the EPHX1 gene that produces two protein variants.

SUBJECTS AND METHODS

A total of 604 samples belonging to 13 Indian populations were included in this study. Based on the DSM-IV criteria, 184 individuals from Kota population were classified into alcoholism cases (100) and controls (84). Genotypes of Tyr113His and His139Arg polymorphisms in the EPHX1 gene were determined using PCR and sequencing. Associations were tested using Pearson's χ(2) test and haplotype analyses.

RESULTS

We found significant association between EPHX1 gene Tyr113His polymorphism and alcoholism in the Kota population (T vs. C: OR = .615, 95% CI = .399-.949, p = .027; TT vs. CC + CT: OR = .536, 95% CI = .297-.969, p = .038). The very slow activity haplotype CA (113His-139His) was also found to be associated with alcohol dependence (p = .048). Analysis of additional populations demonstrated that the Tyr113His polymorphism significantly deviated from Hardy-Weinberg equilibrium in four populations but only one population deviated for the His139Arg locus. All populations shared the four possible two-site haplotypes. Linkage disequilibrium between these two loci was not significant in any of the population studied.

CONCLUSION

EPHX1 gene polymorphisms and haplotypes are associated with an increased risk for alcoholism in the Kota population. This is the first report from India that will serve as a template for future investigations of the prevalence of EPHX1 alleles in association with various clinical entities.

Association of NQO1 rs1800566 polymorphism and the risk of colorectal cancer: a meta-analysis

INTRODUCTION

NAD(P)H:quinone oxidoreductase 1 (NQO1) rs1800566 polymorphism is found to have a lower enzymatic activity, which may result in increased incidence of several kinds of carcinomas including colorectal cancer. Results from published studies on the association of NQO1 rs1800566 genetic polymorphism with the risk of colorectal cancer are inconsistent. We performed a meta-analysis to summarize the possible association.

MATERIALS AND METHODS

All eligible published studies were searched from PubMed and Elsevier ScienceDirect. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were analyzed for additive, dominant, and recessive models to assess the association using fixed- or random-effect model.

RESULTS

We identified 12 case-control studies that include 5,525 cases and 6,272 controls for the present meta-analysis. Significant associations between NQO1 rs1800566 genetic polymorphism and risk of colorectal cancer were observed in additive (OR = 1.09, 95% CI = 1.02-1.16, p = 0.009) and dominant models (OR = 1.12, 95% CI = 1.04-1.21, p = 0.004 for TT + CT vs. CC). Moreover, in the subgroup analysis based on ethnicity, significant associations were observed in Caucasians but not in Asians.

CONCLUSIONS

This meta-analysis provided evidence that NQO1 rs1800566 genetic polymorphism was associated with increased risk of colorectal cancer and that the T allele probably acts as an important risk factor.

Microsomal epoxide hydrolase polymorphisms, cigarette smoking, and risk of colorectal cancer: the Fukuoka Colorectal Cancer Study

Microsomal epoxide hydrolase (EPHX1) plays an important role in the activation and detoxification of polycyclic aromatic hydrocarbons, carcinogens found in cigarette smoke. Polymorphisms in exon 3 (Y113H) and exon 4 (H139R) of the EPHX1 have been associated with enzyme activity. We investigated the risk of colorectal cancer in relation to the EPHX1 Y113H and H139R polymorphisms and assessed effect modifications of cigarette smoking and the other covariates. The interaction between the EPHX1 polymorphisms and selected genetic polymorphisms was also examined. We used data from Fukuoka Colorectal Cancer Study, a community-based case-control study, including 685 cases and 778 controls. In-person interviews were conducted to assess lifestyle factors. The EPHX1 Y113H and H139R polymorphisms were determined by the TaqMan assay and the polymerase chain reaction-restriction fragment length polymorphism, respectively. Neither of the two polymorphisms nor the imputed EPHX1 phenotype was associated with colorectal cancer risk. Cigarette smoking and alcohol intake showed no effect modification on the association with the EPHX1 polymorphisms or the imputed EPHX1 phenotype. Increased risks of colorectal cancer associated with the 113Y allele and imputed EPHX1 phenotype were observed among individuals with high body mass index (BMI; ≥25.0 kg/m(2)), but not among those with low BMI (<25.0 kg/m(2)). The risk decreased with an increasing number of the 139R allele in the null genotypes of GSTM1/GSTT1. It is unlikely that the EPHX1 polymorphisms play an important role in colorectal carcinogenesis. The observed interactions of the EPHX1 polymorphisms with BMI and the GSTM1/GSTT1 genotypes warrant further investigation.

Contribution of NAD(P)H quinone oxidoreductase 1 (NQO1) Pro187Ser polymorphism and risk of colorectal adenoma and colorectal cancer in Caucasians: a meta-analysis

BACKGROUND AND AIMS

The effects of polymorphism of NAD(P)H quinone oxidoreductase 1 (NQO1 Pro187Ser, rs1800566) on the risks of colorectal adenoma and cancer have been widely studied and results remain controversial. Therefore, the aim of this meta-analysis was to quantitatively assess the relationships.

METHODS

Databases of Medline, Embase and Wanfang were retrieved until May 15, 2011. Pooled odds ratio (OR) and 95% confidence interval (95% CI) as effect sizes were calculated by using fixed- or random-effect model. Cochrane Q-test was used to explore between-study heterogeneity; p <0.10 indicated statistical significance.

RESULTS

A total of 12 case-control studies with 11,700 individuals (including 5528 cases and 6172 controls) were included in this meta-analysis. Of these studies, four studies conducted in Caucasian populations were for colorectal adenoma, and eight studies were for colorectal cancer. NQO1 187Ser allele was significantly associated with increased risk of colorectal adenoma in co-dominant and dominant comparison models (OR = 1.07, 95% CI = 1.04-1.32 for ProSer vs. ProPro and OR = 1.19, 95% CI = 1.06-1.33 for Ser carries vs. ProPro), without between-study heterogeneity. Overall, NQO1 Pro187Ser was not associated with risk of colorectal cancer, without between-study heterogeneity. Subgroup analyses indicated that Ser allele was significantly associated with increased risk of colorectal cancer for Caucasians (OR = 1.14, 95% CI = 1.00-1.30 for ProSer vs. ProPro and OR = 1.16, 95% CI = 1.02-1.31 for Ser carries vs. ProPro).

CONCLUSIONS

This meta-analysis suggested that Ser allele of NQO1 Pro187Ser significantly contributed to the increased risks of colorectal adenoma and cancer in Caucasians.

Red meat consumption and cancer: reasons to suspect involvement of bovine infectious factors in colorectal cancer

An increased risk for colorectal cancer has been consistently reported for long-time consumption of cooked and processed red meat. This has frequently been attributed to chemical carcinogens arising during the cooking process of meat. Long-time fish or poultry consumption apparently does not increase the risk, although similar or higher concentrations of chemical carcinogens were recorded in their preparation for consumption. The geographic epidemiology of colorectal cancer seems to correspond to regions with a high rate of beef consumption. Countries with a virtual absence of beef in the diet (India) or where preferably lamb or goat meat is consumed (several Arabic countries) reveal low rates of colorectal cancer. In China, pork consumption has a long tradition, with an intermediate colorectal cancer rate. In Japan and Korea, large scale beef and pork imports started after World War II or after the Korean War. A steep rise in colorectal cancer incidence was noted after 1970 in Japan and 1990 in Korea. The consumption of undercooked beef (e.g., shabu-shabu, Korean yukhoe and Japanese yukke) became very popular in both countries. The available data are compatible with the interpretation that a specific beef factor, suspected to be one or more thermoresistant potentially oncogenic bovine viruses (e.g., polyoma-, papilloma- or possibly single-stranded DNA viruses) may contaminate beef preparations and lead to latent infections in the colorectal tract. Preceding, concomitant or subsequent exposure to chemical carcinogens arising during cooking procedures should result in increased risk for colorectal cancer synergistic with these infections.

A functional NQO1 609C>T polymorphism and risk of gastrointestinal cancers: a meta-analysis

Background

The functional polymorphism (rs1800566) in the NQO1 gene, a 609C>T substitution, leading to proline-to-serine amino-acid and enzyme activity changes, has been implicated in cancer risk, but individually published studies showed inconclusive results.

Methodology/Principal Findings

We performed a meta-analysis of 20 publications with a total of 5,491 cases and 5,917 controls, mainly on gastrointestinal (GI) cancers. We summarized the data on the association between the NQO1 609C>T polymorphism and risk of GI cancers and performed subgroup analyses by ethnicity, cancer site, and study quality. We found that the variant CT heterozygous and CT/TT genotypes of the NQO1 609 C>T polymorphism were associated with a modestly increased risk of GI cancers (CT vs. CC: OR = 1.10, 95% CI = 1.01 – 1.19, P_{heterogeneity} = 0.27, I² = 0.15; CT/TT vs. CC: OR = 1.11, 95%CI = 1.02 – 1.20, P_{heterogeneity} = 0.14; I² = 0.27). Following further stratified analyses, the increased risk was only observed in subgroups of Caucasians, colorectal cancer in Caucasians, and high quality studies.

Conclusions

This meta-analysis suggests that the NQO1 609T allele is a low-penetrance risk factor for GI cancers. Although the effect on GI cancers may be modified by ethnicity and cancer sites, small sample seizes of the subgroup analyses suggest that further larger studies are needed, especially for non-colorectal GI cancers in Caucasians and GI cancers in Asians.

System review and metaanalysis of the relationships between five metabolic gene polymorphisms and colorectal adenoma risk

The relationships between some metabolic (including EPHX1, GSTs and NQO1) gene polymorphisms and colorectal adenoma (CRA) risk have been commonly studied, and no conclusions are available up to now. Therefore, we quantitatively studied the relationships by a metaanalysis. The databases of Medline and Embase were retrieved updated to June 15th, 2011. Crude or adjusted odds ratio (crude OR or adjusted OR) and 95% confidence interval (95%CI) were calculated to present the strength of the associations. Overall, nine case-control studies for EPHX1 Tyr113His and His139Arg, five case-control studies for GSTM1, four studies for GSTP1 Ile105Val, two studies for GSTP1 Ala114Val, six studies for GSTT1 and four studies for NQO1 Pro187Ser were included in this metaanalysis. The results of combined analyses indicated that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val were not associated with CRA risk [crude OR (95%CI): 0.98 (0.90-1.07) and P ( z-test) = 0.65 for EPHX1 His carriers vs. Tyr/Tyr; 1.05 (0.97-1.15) and P ( z-test) = 0.21 for EPHX1 Arg carriers vs. His/His; 1.05 (0.92-1.20) and P ( z-test) = 0.47 for GSTT1 Null vs. Present; 1.01 (0.90-1.13) and P ( z-test) = 0.90 for GSTM1 Null vs. Present; 1.04 (0.92-1.17) and P ( z-test) = 0.56 for G carriers vs. AA for GSTP1 Ile105Val; 0.88 (0.70-1.11) and P ( z-test) = 0.28 for T carriers vs. CC for GSTP1 Ala114Val]. In contrast, Ser allele of NQO1 Ser187Pro might be a modest risk factor for CRA development [1.19 (1.06-1.33) and P ( z-test) = 0.003 for Ser carriers vs. Pro/Pro]. To get more precise evidences, adjusted ORs (95%CI) for EPHX1 Tyr113His, His139Arg, GSTP1 Ile105Val and NQO1 Ser187Pro were also calculated based on adjusted ORs (95%CIs) reported in primary studies. The results still indicated that EPHX1 Tyr113His, His139Arg and GSTP1 Ile105Val were not associated with CRA risk except for NQO1 Ser187Pro. When subgroup analyses were performed for population-based case-control studies or studies in HWE for EPHX1 Tyr113His and His139Arg, and NQO1 Ser187Pro polymorphisms, the results were persistent. Although with modest limitations and biases, this metaanalysis suggests that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val polymorphisms may be not risk factors for CRA development, while Ser allele of NQO1 Ser187 Pro may be a modest risk factor for CRA development, and may be used with other genetic markers for screening CRA in the future.

Associations of cigarette smoking and alcohol consumption with advanced or multiple colorectal adenoma risks: a colonoscopy-based case-control study in Korea

The associations between alcohol consumption and cigarette smoking habits and the risk for colorectal adenomatous polyps according to the detailed clinical information about polyps were assessed in a large colonoscopy-based study. The study enrolled participants who visited the National Cancer Center of the Republic of Korea for cancer screening between April 2007 and April 2009. In 1,242 newly diagnosed colorectal adenoma patients and 3,019 polyp-free controls, past smokers (odds ratio (OR) = 1.31, 95% confidence interval (CI): 1.04, 1.65) and current smokers (OR = 1.70, 95% CI: 1.37, 2.11) had increased risks for adenomas compared with nonsmokers. Cigarette smoking conferred an even higher risk for advanced adenomas and 3 or more adenomas than for low-risk adenomas or a single adenoma. Dose-response relations were observed among the daily number of cigarettes smoked, the duration of smoking, the pack-years of smoking, and the risk for adenomas. A longer duration of alcohol consumption was associated with a higher risk for advanced adenomas (for >28 years of consumption: OR = 2.0, 95% CI: 1.10, 3.64) and 3 or more adenomas (OR = 2.19, 95% CI: 1.27, 3.76). In conclusion, cigarette smoking and alcohol consumption play roles in colorectal carcinogenesis, and the association differs by the clinical features of the adenomas.

Putative EPHX1 enzyme activity is related with risk of lung and upper aerodigestive tract cancers: a comprehensive meta-analysis

Background

EPHX1 is a key enzyme in metabolizing some exogenous carcinogens such as products of cigarette-smoking. Two functional polymorphisms in the EPHX1 gene, Tyr113His and His139Arg can alter the enzyme activity, suggesting their possible association with carcinogenesis risk, particularly of some tobacco-related cancers.

Methodology/Principal Findings

A comprehensive systematic review and meta-analysis was performed of available studies on these two polymorphisms and cancer risk published up to November 2010, consisting of 84 studies (31144 cases and 42439 controls) for Tyr113His and 77 studies (28496 cases and 38506 controls) for His139Arg primarily focused on lung cancer, upper aerodigestive tract (UADT) cancers (including oral, pharynx, larynx and esophagus cancers), colorectal cancer or adenoma, bladder cancer and breast cancer. Results showed that Y113H low activity allele (H) was significantly associated with decreased risk of lung cancer (OR = 0.88, 95%CI = 0.80–0.96) and UADT cancers (OR = 0.86, 95%CI = 0.77–0.97) and H139R high activity allele (R) with increased risk of lung cancer (OR = 1.18, 95%CI = 1.04–1.33) but not of UADT cancers (OR = 1.05, 95%CI = 0.93–1.17). Pooled analysis of lung and UADT cancers revealed that low EPHX1 enzyme activity, predicted by the combination of Y113H and H139R showed decreased risk of these cancers (OR = 0.83, 95%CI = 0.75–0.93) whereas high EPHX1 activity increased risk of the cancers (OR = 1.20, 95%CI = 0.98–1.46). Furthermore, modest difference for the risk of lung and UADT cancers was found between cigarette smokers and nonsmokers both in single SNP analyses (low activity allele H: OR = 0.77/0.85 for smokers/nonsmokers; high activity allele R: OR = 1.20/1.09 for smokers/nonsmokers) and in combined double SNP analyses (putative low activity: OR = 0.73/0.88 for smokers/nonsmokers; putative high activity: OR = 1.02/0.93 for smokers/ nonsmokers).

Conclusions/Significance

Putative low EPHX1 enzyme activity may have a potential protective effect on tobacco-related carcinogenesis of lung and UADT cancers, whereas putative high EPHX1 activity may have a harmful effect. Moreover, cigarette-smoking status may influence the association of EPHX1 enzyme activity and the related cancer risk.

Colorectal polyp type and the association with charred meat consumption, smoking, and microsomal epoxide hydrolase polymorphisms

We determined the association between charred meat consumption, cigarette smoking, microsomal epoxide hydrolase (mEH) polymorphisms (rs1051740 and rs2234922), and colorectal adenomas and hyperplastic polyps (HPs) and explored gene-environment interactions. Men and women with colorectal adenomas (n = 519), HPs (n = 691), or concurrently with both types of polyps (n = 227) and polyp-free controls (n = 772) receiving a colonoscopy from December 2004 to September 2007 were recruited. Participants completed telephone interviews and provided buccal cell samples; genotyping of mEH was completed using Taqman assays. We conducted polytomous regression and calculated odd ratios (OR) and 95% confidence intervals. Interactions were evaluated using Wald chi-square tests. Consumption of >3 servings of charred meat per week was associated with distal HPs (OR = 2.0, 1.2-3.4) but not adenomas nor either type of proximal polyp. Heavy cigarette smoking (≥ 22 pack-years) was associated with an increased risk for colorectal adenomas (OR = 1.7, 95% CI: 1.2-2.4), HPs (OR = 2.4, 95% CI: 1.7-3.3), and both types (OR = 2.8, 95% CI: 1.8-4.3) with the strongest association for distal polyps. There was no association between mEH genotype and colorectal polyps, nor were any statistically significant gene-environment interactions identified. Future investigation of BaP exposure and colorectal neoplasia should analyze whether associations are dependent upon anatomic location.

Polymorphisms in genes encoding drugs and xenobiotic metabolizing enzymes in a Brazilian population

Polymorphic variations of several genes associated with drugs and xenobiotic metabolism have been linked to the factors that predispose to the carcinogenesis process. As considerable interindividual and interethnic variation in metabolizing enzyme activity has been associated with polymorphic alleles, we evaluated the frequency of the polymorphisms of CYP2D6, EPHX1 and NQO1 genes in 361 Brazilian individuals separated by ethnicity (European and African ancestry), using the polymerase chain reaction-restriction fragment length (PCR-RFLP) method. The allele frequencies of the variants *3 and *4 for the gene CYP2D6 were 0.04 and 0.14 for white subjects and 0.03 and 0.10 for black individuals, respectively. For the both variants of the gene EPHX1, we found higher allele frequencies among white individuals compared with mulatto subjects (0.62 vs 0.54 and 0.18 vs 0.14, respectively); however, these differences were not statistically significant (p = 0.39 and 0.56, respectively). For the NQO1 gene we observed a higher frequency of the homozygous genotype among black individuals (7.9%) compared with white subjects (6.3%) (p = 0.003). The genotype frequencies were within the Hardy-Weinberg equilibrium. We concluded that the allele frequencies of CYP2D6, EPHX1 and NQO1 gene polymorphisms in this Brazilian population showed ethnic variability when compared with those observed in other populations.

Genetic polymorphisms in glutathione S-transferase T1 affect the surgical outcome of varicocelectomies in infertile patients

Glutathione S-transferases (GSTs), superoxide dismutase 2 (SOD2) and NAD(P)H:quinone oxidoreductase 1 (NQO1) are anti-oxidant enzyme genes. Polymorphisms of GSTs, SOD2 and NQO1 have been reported to influence individual susceptibility to various diseases. In an earlier study, we obtained preliminary findings that a subset of glutathione S-transferase T1 (GSTT1)-wt patients with varicocele may exhibit good response to varicocelectomy. In this study, we extended the earlier study to determine the distribution of genotype of each gene in the infertile population and to evaluate whether polymorphism of these genes affects the results of surgical treatment of varicocele. We analyzed 72 infertile varicocele patients, 202 infertile patients without varicocele and 101 male controls. Genotypes of GSTs were determined by polymerase chain reaction (PCR). Genotyping of SOD2 and NQO1 was performed using the PCR-restriction fragment length polymorphism (PCR-RFLP) method. A significantly better response to varicocelectomy was found in patients with the GSTT1-wt genotype (63.2%) and NQO1-Ser/Ser genotype (80.0%) than in those with GSTT1-null genotype (35.3%) and NQO1-Pro/Pro or NQO1-Pro/Ser genotype (45.2%), respectively. The frequencies of glutathione S-transferase M1/T1, SOD2 and NQO1 genotypes did not differ significantly among the varicocele patients, idiopathic infertile patients and male controls. GSTT1 genotype is associated with improvement of semen parameters after varicocelectomy. As the number of patients with NQO1-Ser/Ser genotype was not sufficient to reach definite conclusions, the association of NQO1 genotype with varicocelectomy requires further investigation.

NQO1 and NFE2L2 polymorphisms, fruit and vegetable intake and smoking and the risk of colorectal adenomas in an endoscopy-based population

Both environment and genetics contribute to the pathogenesis and prevention of colorectal neoplasia.

NAD(P)H

quinone oxidoreductase (NQO1) is a detoxification enzyme that is polymorphic and inducible. We investigated interactions between lifestyle factors and polymorphisms in NQO1 and its key regulatory transcription factor NFE2L2 in colorectal adenoma risk. The NQO1 c.609C>T and g.-718A>G and NFE2L2 g.-650C>A, g.-684G>A and g.-686A>G polymorphisms were determined among 740 Dutch adenoma cases and 698 endoscopy-based controls. Dietary intake was assessed by food frequency questionnaire, other lifestyle information by questionnaire. The NQO1 609CT genotype was associated with a higher adenoma risk (OR 1.27, 95% CI 1.00-1.62) compared with the 609CC genotype, whereas the 609TT genotype was not (OR 1.03, 95% CI 0.56-1.88). The higher risk with the NQO1 609CT-genotype was seen among smokers (OR 1.96, 95% CI 1.40-2.76), but not among nonsmokers (OR 0.91, 95% CI 0.62-1.35; interaction p = 0.030). Fruit and vegetable consumption did not protect smokers from adenomas and did not interact with the NQO1 609C>T polymorphism or the NFE2L2 polymorphisms. A higher adenoma risk seen with high fruit and vegetable consumption among NQO1 -718GG genotypes was absent among -718GA genotypes (interaction p = 0.071). Gene-gene interactions were observed between the NQO1 609C>T and NFE2L2 -686A>G polymorphisms (interaction p = 0.056) and between the NQO1 -718 G>A and NFE2L2 -650C>A polymorphisms (interaction p = 0.013).

IN CONCLUSION

the NQO1 609CT genotype is associated with increased adenoma risk among smokers, which is not diminished by high fruit and vegetable consumption. The observed gene-gene interactions may point to a role for NFE2L2 polymorphisms in NQO1-related adenoma formation.