Gene Summary

Gene:EPHX1; epoxide hydrolase 1
Aliases: MEH, EPHX, EPOX, HYL1
Summary:Epoxide hydrolase is a critical biotransformation enzyme that converts epoxides from the degradation of aromatic compounds to trans-dihydrodiols which can be conjugated and excreted from the body. Epoxide hydrolase functions in both the activation and detoxification of epoxides. Mutations in this gene cause preeclampsia, epoxide hydrolase deficiency or increased epoxide hydrolase activity. Alternatively spliced transcript variants encoding the same protein have been found for this gene.[provided by RefSeq, Dec 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:epoxide hydrolase 1
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Pharyngeal Neoplasms
  • Taiwan
  • Sensitivity and Specificity
  • Tyrosine
  • Sex Factors
  • Cervical Cancer
  • Risk Assessment
  • Pleural Neoplasms
  • Urine
  • Smoking
  • Exons
  • Genetic Predisposition
  • Xenobiotics
  • Quinone Reductases
  • Serum Albumin
  • Glutathione Transferase
  • Case-Control Studies
  • Transcription
  • Chromosome 1
  • Polymerase Chain Reaction
  • Genotype
  • Epoxide Hydrolases
  • Colorectal Cancer
  • Alleles
  • Sulfotransferases
  • NADP
  • Tobacco Smoke Pollution
  • Bladder Cancer
  • Surveys and Questionnaires
  • Vegetables
  • Polymorphism
  • Restriction Fragment Length Polymorphism
  • Risk Factors
  • Cytochrome P-450 CYP1A1
  • Signal Transduction
  • Prostate Cancer
  • Sex Characteristics
  • Tobacco
  • Young Adult
  • Lung Cancer
Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: EPHX1 (cancer-related)

Cheng H, Huang C, Tang G, et al.
Emerging role of EPHX1 in chemoresistance of acute myeloid leukemia by regurlating drug-metabolizing enzymes and apoptotic signaling.
Mol Carcinog. 2019; 58(5):808-819 [PubMed] Related Publications
Microsomal epoxide hyrolase 1 (EPHX1) is a critical biotransformation enzyme and participants in both the detoxification and activation of potentially genotoxic epoxides. In this study, we firstly aimed to investigate the role of EPHX1 in the chemoresistance of acute myeloid leukemic cells to aclarubicin (ACM) and mitoxantrone (MIT). EPHX1 mRNA expression and prognosis were measured in acute myeloid leukemia (AML) patients, and the function of EPHX1 in leukemic cell viability and apoptosis induced by ACM and MIT was also measured. Our results found that EPHX1 expression is obviously associated with recurrence rate, overall survival and time of obtaining first complete remission in AML patients. EPHX1 silencing promoted ACM and MIT induced decrease in cell viability and cell apoptosis of HL-60, K562, and THP-1 that was inhibited by EPHX1 overexpression. EPHX1 reduced the susceptibility of leukemic cells to ACM and MIT by regulating drug-metabolizing enzymes (CYP1A1, GSTM1, and GSTT1) and apoptotic signaling (Bax, Bcl-2, Caspase-3, Caspase-9, and PARP1). Moreover, Nrf2 overexpression significantly increased EPHX1 expression and leukemic cell viability and decreased leukemic cell apoptosis. Taken together, we summarized the recent findings about the chemoresistance-promoting role of EPHX1, and the potential of targeting EPHX1 was proposed to counteract drug resistance in leukemia treatment.

O'Brien KM, Sandler DP, Xu Z, et al.
Vitamin D, DNA methylation, and breast cancer.
Breast Cancer Res. 2018; 20(1):70 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Vitamin D has anticarcinogenic and immune-related properties and may protect against some diseases, including breast cancer. Vitamin D affects gene transcription and may influence DNA methylation.
METHODS: We studied the relationships between serum vitamin D, DNA methylation, and breast cancer using a case-cohort sample (1070 cases, 1277 in subcohort) of non-Hispanic white women. For our primary analysis, we used robust linear regression to examine the association between serum 25-hydroxyvitamin D (25(OH)D) and methylation within a random sample of the cohort ("subcohort"). We focused on 198 CpGs in or near seven vitamin D-related genes. For these 198 candidate CpG loci, we also examined how multiplicative interactions between methylation and 25(OH)D were associated with breast cancer risk. This was done using Cox proportional hazards models and the full case-cohort sample. We additionally conducted an exploratory epigenome-wide association study (EWAS) of the association between 25(OH)D and DNA methylation in the subcohort.
RESULTS: Of the CpGs in vitamin D-related genes, cg21201924 (RXRA) had the lowest p value for association with 25(OH)D (p = 0.0004). Twenty-two other candidate CpGs were associated with 25(OH)D (p < 0.05; RXRA, NADSYN1/DHCR7, GC, or CYP27B1). We observed an interaction between 25(OH)D and methylation at cg21201924 in relation to breast cancer risk (ratio of hazard ratios = 1.22, 95% confidence interval 1.10-1.34; p = 7 × 10
CONCLUSIONS: 25(OH)D concentrations were associated with DNA methylation of CpGs in several vitamin D-related genes, with potential links to immune function-related genes. Methylation of CpGs in vitamin D-related genes may interact with 25(OH)D to affect the risk of breast cancer.

Piltti J, Bygdell J, Qu C, Lammi MJ
Effects of long-term low oxygen tension in human chondrosarcoma cells.
J Cell Biochem. 2018; 119(2):2320-2332 [PubMed] Related Publications
The cell-based therapies could be potential methods to treat damaged cartilage tissues. Instead of native hyaline cartilage, the current therapies generate mainly weaker fibrocartilage-type of repair tissue. A correct microenvironment influences the cellular phenotype, and together with external factors it can be used, for example, to aid the differentiation of mesenchymal stem cells to defined types of differentiated adult cells. In this study, we investigated the effect of long-term exposure to 5% low oxygen atmosphere on human chondrosarcoma HCS-2/8 cells. This atmosphere is close to normal oxygen tension of cartilage tissue. The proteome was analyzed with label-free mass spectrometric method and further bioinformatic analysis. The qRT-PCR method was used to gene expression analysis, and ELISA and dimethylmethylene blue assays for type II collagen and sulfated glycosaminoglycan measurements. The 5% oxygen atmosphere did not influence cell proliferation, but enhanced slightly ACAN and COL2A1 gene expression. Proteomic screening revealed a number of low oxygen-induced protein level responses. Increased ones included NDUFA4L2, P4HA1, NDRG1, MIF, LDHA, PYGL, while TXNRD1, BAG2, TXN2, AQSTM1, TNFRSF1B, and EPHX1 decreased during the long-term low oxygen atmosphere. Also a number of proteins previously not related to low oxygen tension changed during the treatment. Of those S100P, RPSS26, NDUFB11, CDV3, and TUBB8 had elevated levels, while ALCAM, HLA-B, EIF1, and ACOT9 were lower in the samples cultured at low oxygen tension. In conclusion, low oxygen condition causes changes in the cellular amounts of several proteins.

Srivastava D
Microsomal epoxide hydrolase gene polymorphisms and susceptibility to prostate cancer: A systematic review.
Indian J Cancer. 2016 Apr-Jun; 53(2):213-215 [PubMed] Related Publications
Microsomal epoxide hydrolase (mEH) is a crucial biotransformation enzyme that has capability to metabolize a large number of structurally divergent, highly reactive epoxides, and numerous environmentally exposed carcinogens. It catalyzes the conversion of xenobiotic epoxide compounds into more polar diol metabolites and may play important part of the enzymatic defense against adverse effects of foreign compounds. Most commonly, two functional polymorphisms affecting mEH enzyme activity have been identified: One in exon 3 and other in exon 4 of the mEH gene, which results in His113Tyr and Arg139His amino acid substitutions, respectively. Recent reports have shown that polymorphisms in mEH gene loci may an important risk factor for susceptibility of prostate cancers (PCs), worldwide, but inconsistent finding were also be illustrated. To the best of our knowledge, globally, there is no any systematic review has been published related to mEH gene polymorphisms and PC risk. Thus, in the current review, we have discussed the association between mEH gene polymorphisms, gene-environmental interaction, and PC risk.

Fernandes GM, Russo A, Proença MA, et al.
World J Gastroenterol. 2016; 22(45):9974-9983 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate the contribution of polymorphisms in the
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
RESULTS: Age over 62 years was a risk factor for SCRC development (OR = 7.54, 95%CI: 4.94-11.50,
CONCLUSION: In conclusion, the results demonstrated that

Hsu LI, Wu MM, Wang YH, et al.
Association of Environmental Arsenic Exposure, Genetic Polymorphisms of Susceptible Genes, and Skin Cancers in Taiwan.
Biomed Res Int. 2015; 2015:892579 [PubMed] Free Access to Full Article Related Publications
Deficiency in the capability of xenobiotic detoxification and arsenic methylation may be correlated with individual susceptibility to arsenic-related skin cancers. We hypothesized that glutathione S-transferase (GST M1, T1, and P1), reactive oxygen species (ROS) related metabolic genes (NQO1, EPHX1, and HO-1), and DNA repair genes (XRCC1, XPD, hOGG1, and ATM) together may play a role in arsenic-induced skin carcinogenesis. We conducted a case-control study consisting of 70 pathologically confirmed skin cancer patients and 210 age and gender matched participants with genotyping of 12 selected polymorphisms. The skin cancer risks were estimated by odds ratio (OR) and 95% confidence interval (CI) using logistic regression. EPHX1 Tyr113His, XPD C156A, and GSTT1 null genotypes were associated with skin cancer risk (OR = 2.99, 95% CI = 1.01-8.83; OR = 2.04, 95% CI = 0.99-4.27; OR = 1.74, 95% CI = 1.00-3.02, resp.). However, none of these polymorphisms showed significant association after considering arsenic exposure status. Individuals carrying three risk polymorphisms of EPHX1 Tyr113His, XPD C156A, and GSTs presented a 400% increased skin cancer risk when compared to those with less than or equal to one polymorphism. In conclusion, GSTs, EPHX1, and XPD are potential genetic factors for arsenic-induced skin cancers. The roles of these genes for arsenic-induced skin carcinogenesis need to be further evaluated.

Matejcic M, Iqbal Parker M
Gene-environment interactions in esophageal cancer.
Crit Rev Clin Lab Sci. 2015; 52(5):211-31 [PubMed] Related Publications
Esophageal cancer (EC) is one of the most common malignancies in low- and medium-income countries and represents a disease of public health importance because of its poor prognosis and high mortality rate in these regions. The striking variation in the prevalence of EC among different ethnic groups suggests a significant contribution of population-specific environmental and dietary factors to susceptibility to the disease. Although individuals within a demarcated geographical area are exposed to the same environment and share similar dietary habits, not all of them will develop the disease; thus genetic susceptibility to environmental risk factors may play a key role in the development of EC. A wide range of xenobiotic-metabolizing enzymes are responsible for the metabolism of carcinogens introduced via the diet or inhaled from the environment. Such dietary or environmental carcinogens can bind to DNA, resulting in mutations that may lead to carcinogenesis. Genes involved in the biosynthesis of these enzymes are all subject to genetic polymorphisms that can lead to altered expression or activity of the encoded proteins. Genetic polymorphisms may, therefore, act as molecular biomarkers that can provide important predictive information about carcinogenesis. The aim of this review is to discuss our current knowledge on the genetic risk factors associated with the development of EC in different populations; it addresses mainly the topics of genetic polymorphisms, gene-environment interactions, and carcinogenesis. We have reviewed the published data on genetic polymorphisms of enzymes involved in the metabolism of xenobiotics and discuss some of the potential gene-environment interactions underlying esophageal carcinogenesis. The main enzymes discussed in this review are the glutathione S-transferases (GSTs), N-acetyltransferases (NATs), cytochrome P450s (CYPs), sulfotransferases (SULTs), UDP-glucuronosyltransferases (UGTs), and epoxide hydrolases (EHs), all of which have key roles in the detoxification of environmental and dietary carcinogens. Finally, we discuss recent advances in the study of genetic polymorphisms associated with EC risk, specifically with regard to genome-wide association studies, and examine possible challenges of case-control studies that need to be addressed to better understand the interaction between genetic and environmental factors in esophageal carcinogenesis.

Václavíková R, Hughes DJ, Souček P
Microsomal epoxide hydrolase 1 (EPHX1): Gene, structure, function, and role in human disease.
Gene. 2015; 571(1):1-8 [PubMed] Free Access to Full Article Related Publications
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.

Zhong JH, Li LQ, Mo XS, et al.
Meta-analysis of microsomal epoxide hydrolase gene polymorphism and the risk of breast carcinoma.
Genet Mol Res. 2015; 14(2):4133-41 [PubMed] Related Publications
Carcinogenesis of breast carcinoma is very complicated. Previous studies have suggested conflicting results regarding the association between Tyr113His and His139Arg microsomal epoxide hydrolase (mEH) gene polymorphisms and risk of breast carcinoma. We conducted a meta-analysis to examine the relationship between these polymorphisms and breast carcinoma risk. We searched the PubMed, EMBASE, and Google Scholar databases to identify relevant studies. After extracting relevant data, the association between mEH polymorphisms and susceptibility to breast carcinoma was examined by meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of the association. Seven studies were identified that included 6357 cases and 8090 controls. The mEH His-allele was not associated with the risk of breast carcinoma based on the allelic contrast model (OR = 0.99, 95%CI = 0.94-1.04, P = 0.58), dominant genetic model (OR = 1.14, 95%CI = 0.88-1.48, P = 0.33), or recessive genetic model (OR = 1.03, 95%CI = 0.96-1.10, P = 0.43). Similarly, the mEH Arg-allele was not associated with breast carcinoma risk based on the allelic contrast model (OR = 0.97, 95%CI = 0.91-1.04, P = 0.44), dominant genetic model (OR = 1.01, 95%CI = 0.84-1.21, P = 0.94), or recessive genetic model (OR = 1.04, 95%CI = 0.96-1.12, P = 0.35). Subgroup analysis based on ethnicity showed no association between the polymorphisms and risk of breast carcinoma. Thus, the Tyr113His and His139Arg mEH polymorphisms may not be risk factors for breast carcinoma.

Chen H, Ge L, Sui Q, Lin M
Systematic Review and Meta-Analysis of the Relationship between EPHX1 Polymorphisms and the Risk of Head and Neck Cancer.
PLoS One. 2015; 10(4):e0123347 [PubMed] Free Access to Full Article Related Publications
AIM: To evaluate the association between the EPHX1 Tyr113His and His139Arg polymorphisms in the EPHX1 gene and the risk of head and neck cancer.
MATERIALS AND METHODS: Studies on the association of EPHX1 Tyr113His and His139Arg polymorphisms with HNC performed up until June 1st, 2014, were identified using a predefined search strategy. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the strength of these associations.
RESULTS: In this meta-analysis, 10 case-control studies, which included 9 studies of Tyr113His (1890 cases and 1894 controls) and 10 studies of His139Arg polymorphisms (1982 cases and 2024 controls), were considered eligible for inclusion. Overall, the pooled results indicated that the EPHX1 Tyr113His polymorphism was significantly associated with increased HNC risk (Tyr/His vs. Tyr/Tyr, OR = 1.26, 95%1.02-1.57;His/His+ Tyr/His vs. Tyr/Tyr, OR = 1.29, 95% I = 1.03-1.61). However, no significant association was found between the His139Arg polymorphism and HNC risk. In the subgroup analysis, a statistically significant association between the EPHX1 Tyr113His polymorphism and HNC was observed in population-based case-control studies (PCC), which involved less than 500 participants and genotype frequencies in HWE. This association showed minimal heterogeneity after excluding studies that were determined to contribute to heterogeneity. After categorizing the studies by publication time, a sensitivity analysis and cumulative meta-analysis of the two associations were conducted, and the results of the two analyses were consistent.
CONCLUSION: Our meta-analysis suggests that EPHX1 Tyr113His polymorphism may be a risk factor for HNC, while the EPHX1 His139Arg polymorphism has no association with HNC risk.

Moorthy B, Chu C, Carlin DJ
Polycyclic aromatic hydrocarbons: from metabolism to lung cancer.
Toxicol Sci. 2015; 145(1):5-15 [PubMed] Free Access to Full Article Related Publications
Excessive exposure to polycyclic aromatic hydrocarbons (PAHs) often results in lung cancer, a disease with the highest cancer mortality in the United States. After entry into the lung, PAHs induce phase I metabolic enzymes such as cytochrome P450 (CYP) monooxygenases, i.e. CYP1A1/2 and 1B1, and phase II enzymes such as glutathione S-transferases, UDP glucuronyl transferases, NADPH quinone oxidoreductases (NQOs), aldo-keto reductases (AKRs), and epoxide hydrolases (EHs), via the aryl hydrocarbon receptor (AhR)-dependent and independent pathways. Humans can also be exposed to PAHs through diet, via consumption of charcoal broiled foods. Metabolism of PAHs through the CYP1A1/1B1/EH pathway, CYP peroxidase pathway, and AKR pathway leads to the formation of the active carcinogens diol-epoxides, radical cations, and o-quinones. These reactive metabolites produce DNA adducts, resulting in DNA mutations, alteration of gene expression profiles, and tumorigenesis. Mutations in xenobiotic metabolic enzymes, as well as polymorphisms of tumor suppressor genes (e.g. p53) and/or genes involved in gene expression (e.g. X-ray repair cross-complementing proteins), are associated with lung cancer susceptibility in human populations from different ethnicities, gender, and age groups. Although various metabolic activation/inactivation pathways, AhR signaling, and genetic susceptibilities contribute to lung cancer, the precise points at which PAHs induce tumor initiation remain unknown. The goal of this review is to provide a current state-of-the-science of the mechanisms of human lung carcinogenesis mediated by PAHs, the experimental approaches used to study this complex class of compounds, and future directions for research of these compounds.

Yang X, Wang Y, Wang G
Quantitative assessment of the influence of EPHX1 gene polymorphisms and cancer risk: a meta-analysis with 94,213 subjects.
J Exp Clin Cancer Res. 2014; 33:82 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Previous studies investigating the association between EPHX1 polymorphisms (Tyr113His and His139Arg) and cancer risk have yielded inconsistent results. This meta-analysis was performed to derive a more precise estimation of relationship between two EPHX1 polymorphisms and risk of different types of cancer.
METHODS: Data were extracted from relevant studies detected by a systematic literature search. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of the association between EPHX1 polymorphisms and cancer risk.
RESULTS: This meta-analysis carefully collected 99 studies on these two polymorphisms and cancer risk published up to March 2014, consisting of 45 studies (20,091 cases and 27,396 controls) for Tyr113His and 54 studies (19,437 cases and 27,289 controls) for His139Arg. The results in overall population did not show any significant association between these two polymorphisms and cancer risk for all genetic models. However, EPHX1 Tyr113His homozygote individuals have a significantly increased risk of cancer among Asians (homozygote model: OR =1.46, 95% CI=1.05-2.03; recessive model: OR =1.39, 95% CI =1.10-1.76) and mixed population (homozygote model: OR =1.17, 95% CI =1.02-1.34; recessive model: OR =1.17, 95% CI =1.02-1.33), but not Caucasians.
CONCLUSION: His/His genotype of EPHX1 Tyr113His polymorphism is a risk factor for developing caner for Asian and mixed population, while no evidence was found for the association between the EPHX1 His139Arg polymorphism and increased cancer risk.

Tan X, Wang YY, Chen XY, et al.
Quantitative assessment of the effects of the EPHX1 Tyr113His polymorphism on lung and breast cancer.
Genet Mol Res. 2014; 13(3):7437-46 [PubMed] Related Publications
The association between the microsomal epoxide hydrolase 1 gene (EPHX1) Tyr113His polymorphism and lung cancer and breast cancer risk has been reported in many recent studies, but there is no consensus among the results. Thus, we examined the association between the EPHX1 Tyr113His polymorphism and lung cancer through a meta-analysis. A comprehensive literature search was performed using the Pubmed and Embase databases. Odds ratios with 95% confidence intervals were used to assess the strength of associations. Our meta-analysis suggested that the Tyr113His polymorphism was associated with lung cancer risk in Asians under 3 genetic models, including a C vs T, CC vs TT, and recessive model. However, the risk was decreased in Caucasians under the genetic models, including a C vs T, CC vs TT, or CT vs TT, dominant, and recessive model. In contrast, there was no association with breast cancer risk for any of the genetic models. Our meta-analysis suggested that the EPHX1 Tyr113His polymorphism may be a risk factor for lung cancer in Asians, whereas it may be a decreased risk factor among Caucasians. However, this polymorphism was not found to be associated with breast cancer.

Esteban-Jurado C, Vila-Casadesús M, Garre P, et al.
Whole-exome sequencing identifies rare pathogenic variants in new predisposition genes for familial colorectal cancer.
Genet Med. 2015; 17(2):131-42 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Colorectal cancer is an important cause of mortality in the developed world. Hereditary forms are due to germ-line mutations in APC, MUTYH, and the mismatch repair genes, but many cases present familial aggregation but an unknown inherited cause. The hypothesis of rare high-penetrance mutations in new genes is a likely explanation for the underlying predisposition in some of these familial cases.
METHODS: Exome sequencing was performed in 43 patients with colorectal cancer from 29 families with strong disease aggregation without mutations in known hereditary colorectal cancer genes. Data analysis selected only very rare variants (0-0.1%), producing a putative loss of function and located in genes with a role compatible with cancer. Variants in genes previously involved in hereditary colorectal cancer or nearby previous colorectal cancer genome-wide association study hits were also chosen.
RESULTS: Twenty-eight final candidate variants were selected and validated by Sanger sequencing. Correct family segregation and somatic studies were used to categorize the most interesting variants in CDKN1B, XRCC4, EPHX1, NFKBIZ, SMARCA4, and BARD1.
CONCLUSION: We identified new potential colorectal cancer predisposition variants in genes that have a role in cancer predisposition and are involved in DNA repair and the cell cycle, which supports their putative involvement in germ-line predisposition to this neoplasm.

Ruano-Ravina A, Pereyra MF, Castro MT, et al.
Genetic susceptibility, residential radon, and lung cancer in a radon prone area.
J Thorac Oncol. 2014; 9(8):1073-80 [PubMed] Related Publications
INTRODUCTION: Radon exposure has been classified as the second cause of lung cancer, after tobacco, and the first in never smokers. GSTM1 and GSTT1 genes deletion increase the risk of lung cancer. We aim to know whether the risk of lung cancer because of residential radon is modulated by these genetic polymorphisms.
METHODS: Hospital-based, case-control study where cases had confirmed lung cancer. Cases and controls did not have previous neoplasm and were older than 30. Controls attended hospital for noncomplex surgery. We analyzed the results for the whole sample and separately for never/light smokers and moderate/heavy smokers.
RESULTS: Seven-hundred and ninety-two participants were analyzed. GSTM1 and GSTT1 deletion conferred an odds ratio (OR) of 1.38 (95% confidence interval [CI] 0.93-2.04) and 1.13 (95% CI 0.70-1.82), respectively. Individuals with GSTM1 present and residential radon concentrations higher than 148 Bq/m had an OR of 1.48 (95% CI 0.73-3.00), whereas those with GSTM1 deleted had an OR of 2.64 (95% CI 1.18-5.91) when compared with participants with GSTM1 present and radon concentrations below 50 Bq/m3. Similar results were observed for GSTT1 deletion. These results were basically the same for the moderate/heavy smokers' subgroup.
CONCLUSIONS: The absence of GSTM1 and GSTT1 genes increases the risk of lung cancer because of radon exposure. These genes might modulate the carcinogenic pathway of alpha radiation. Further studies are warranted analyzing this association in never smokers.

Gong WF, He W, Zhang QM, et al.
Try113His and His139Arg polymorphisms in the microsomal epoxide hydrolase gene are not associated with risk of breast cancer.
Tumour Biol. 2014; 35(8):8087-93 [PubMed] Related Publications
Breast cancer may be caused by several factors, including polymorphisms in the microsomal epoxide hydrolase (mEH) gene. Previous work suggested an association between mEH polymorphism and risk of breast cancer, but the results have been inconsistent. PubMed, EMBASE, Google Scholar, and the Chinese National Knowledge Infrastructure database were systematically searched to identify relevant studies. A meta-analysis was performed to examine the association between Tyr113His and His139Arg mEH polymorphisms and susceptibility to breast cancer. Odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated to assess the strength of the association. Seven studies involving 6,357 cases and 8,089 controls were included in this study. The Tyr113His mEH polymorphism did not affect breast cancer risk in the allelic contrast model (OR = 0.99, 95 % CI = 0.94-1.04, P = 0.58), the dominant genetic model (OR = 1.14, 95 % CI = 0.88-1.48, P = 0.33), or the recessive genetic model (OR = 1.03, 95 % CI = 0.96-1.10, P = 0.43). Similarly, the His139Arg mEH polymorphism was not associated with breast cancer risk in the allelic contrast model (OR = 0.97, 95 % CI = 0.91-1.04, P = 0.44), the dominant genetic model (OR = 1.01, 95 % CI = 0.84-1.21, P = 0.94), or the recessive genetic model (OR = 1.04, 95 % CI = 0.96-1.12, P = 0.35). The mEH polymorphisms Tyr113His and His139Arg are not risk factors for breast cancer. Further, large and well-designed studies are required to confirm this conclusion.

Chen JY, Chen WN, Jiao BY, et al.
Hepatitis B spliced protein (HBSP) promotes the carcinogenic effects of benzo [alpha] pyrene by interacting with microsomal epoxide hydrolase and enhancing its hydrolysis activity.
BMC Cancer. 2014; 14:282 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The risk of hepatocellular carcinoma (HCC) increases in chronic hepatitis B surface antigen (HBsAg) carriers who often have concomitant increase in the levels of benzo[alpha]pyrene-7,8-diol-9,10-epoxide(±) (BPDE)-DNA adduct in liver tissues, suggesting a possible co-carcinogenesis of Hepatitis B virus (HBV) and benzo[alpha]pyrene in HCC; however the exact mechanisms involved are unclear.
METHODS: The interaction between hepatitis B spliced protein (HBSP) and microsomal epoxide hydrolase (mEH) was confirmed using GST pull-down, co-immunoprecipitation and mammalian two-hybrid assay; the effects of HBSP on mEH-mediated B[alpha]P metabolism was examined by high performance liquid chromatography (HPLC); and the influences of HBSP on B[alpha]P carcinogenicity were evaluated by bromodeoxyuridine cell proliferation, anchorage-independent growth and tumor xenograft.
RESULTS: HBSP could interact with mEH in vitro and in vivo, and this interaction was mediated by the N terminal 47 amino acid residues of HBSP. HBSP could greatly enhance the hydrolysis activity of mEH in cell-free mouse liver microsomes, thus accelerating the metabolism of benzo[alpha]pyrene to produce more ultimate carcinnogen, BPDE, and this effect of HBSP requires the intact HBSP molecule. Expression of HBSP significantly increased the formation of BPDE-DNA adduct in benzo[alpha]pyrene-treated Huh-7 hepatoma cells, and this enhancement was blocked by knockdown of mEH. HBSP could enhance the cell proliferation, accelerate the G1/S transition, and promote cell transformation and tumorigenesis of B[alpha]P-treated Huh-7 hepatoma cells.
CONCLUSIONS: Our results demonstrated that HBSP could promote carcinogenic effects of B[alpha]P by interacting with mEH and enhancing its hydrolysis activity.

Stott-Miller M, Zhao S, Wright JL, et al.
Validation study of genes with hypermethylated promoter regions associated with prostate cancer recurrence.
Cancer Epidemiol Biomarkers Prev. 2014; 23(7):1331-9 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: One challenge in prostate cancer is distinguishing indolent from aggressive disease at diagnosis. DNA promoter hypermethylation is a frequent epigenetic event in prostate cancer, but few studies of DNA methylation in relation to features of more aggressive tumors or prostate cancer recurrence have been completed.
METHODS: We used the Infinium HumanMethylation450 BeadChip to assess DNA methylation in tumor tissue from 407 patients with clinically localized prostate cancer who underwent radical prostatectomy. Recurrence status was determined by follow-up patient surveys, medical record review, and linkage with the Surveillance, Epidemiology, and End Results (SEER) registry. The methylation status of 14 genes for which promoter hypermethylation was previously correlated with advanced disease or biochemical recurrence was evaluated. Average methylation level for promoter region CpGs in patients who recurred compared with those with no evidence of recurrence was analyzed. For two genes with differential methylation, time to recurrence was examined.
RESULTS: During an average follow-up of 11.7 years, 104 (26%) patients recurred. Significant promoter hypermethylation in at least 50% of CpG sites in two genes, ABHD9 and HOXD3, was found in tumors from patients who recurred compared with those without recurrence. Evidence was strongest for HOXD3 (lowest P = 9.46 × 10(-6)), with higher average methylation across promoter region CpGs associated with reduced recurrence-free survival (P = 2 × 10(-4)). DNA methylation profiles did not differ by recurrence status for the other genes.
CONCLUSIONS: These results validate the association between promoter hypermethylation of ADHB9 and HOXD3 and prostate cancer recurrence.
IMPACT: Tumor DNA methylation profiling may help to distinguish patients with prostate cancer at higher risk for disease recurrence.

Su S, Yang X, Omiecinski CJ
Intronic DNA elements regulate Nrf2 chemical responsiveness of the human microsomal epoxide hydrolase gene (EPHX1) through a far upstream alternative promoter.
Biochim Biophys Acta. 2014; 1839(6):493-505 [PubMed] Free Access to Full Article Related Publications
In humans, microsomal epoxide hydrolase (mEH) contributes important biological functions that underlie both detoxification and bioactivation fates arising from exposures to foreign chemicals. Previously, we discovered that human mEH gene transcription is initiated from alternative promoters. The respective transcripts are programmed with tissue specificity and the upstream E1b promoter contributes predominantly to mEH expression. The results presented demonstrate that exposures to the Nrf2 activators, sulforaphane (SFN) and tert-butylhydroquinone (tBHQ), markedly activate E1b transcription in human lung and liver cells. Genomic analyses identified two major DNase I hypersensitive regions (HS-1 and HS-2) within the ~15 kb intervening sequence separating E1b from the downstream E1 promoter. In BEAS-2B cells, the Nrf2 effectors, SFN and tBHQ, selectively activated the more distal HS-2 through an antioxidant response element (ARE). An activator protein 1/12-O-tetradecanoylphorbol-13-acetate interaction was further identified within the HS-2 enhancer that functioned to additionally contribute to ARE-mediated induction responsiveness of the E1b promoter. The results demonstrate that ARE modulation, integrated with additional transcriptional complexes, regulates the tissue-specific expression of mEH and that these processes likely coordinate both the protective and bioactivation functions contributed by mEH activities in human tissues.

Khrunin AV, Khokhrin DV, Moisseev AA, et al.
Pharmacogenomic assessment of cisplatin-based chemotherapy outcomes in ovarian cancer.
Pharmacogenomics. 2014; 15(3):329-37 [PubMed] Related Publications
AIM: Cisplatin and its analogs are potent antitumor agents. However, their use is restricted by significant variability in tumor response and toxicity. There is a great need to identify genetic markers to predict the most important adverse events and patient outcomes.
MATERIALS & METHODS: We have evaluated the association between polymorphisms in 106 genes involved mainly in xenobiotic metabolism, DNA repair, the cell cycle and apoptosis, and outcomes in 104 ovarian cancer patients receiving cisplatin-cyclophosphamide chemotherapy. Arrayed primer extension technology was used to genotype 228 SNPs.
RESULTS: Ten SNPs in nine genes were found to be associated with one or more of the assessed clinical end points. SNPs in TPMT and NQO1 were significantly associated with progression-free survival. Polymorphisms in ERCC5, RAD52, MUTYH and LIG3 correlated with the occurrence of severe neutropenia. SNPs in NAT2 and EPHX1 were associated with anemia and nephrotoxicity, respectively. A SNP in ADH1C was correlated with complete tumor response.
CONCLUSION: The results obtained suggest that SNPs in different genes involved in drug metabolism can be important in identifying patients at risk for nonresponse to or toxicity from cisplatin-based treatment.

Panic N, Mastrostefano E, Leoncini E, et al.
Susceptibility to Helicobacter pylori infection: results of an epidemiological investigation among gastric cancer patients.
Mol Biol Rep. 2014; 41(6):3637-50 [PubMed] Related Publications
The aim of this study was to identify the clinical, demographic, lifestyle factors and selected genetic polymorphisms that affect the susceptibility towards Helicobacter pylori (H. pylori) infection in gastric cancer patients. Histological confirmed gastric adenocarcinoma cases that underwent curative gastrectomy between 2002 and 2012 were included. Gastric biopsy samples were obtained to determine the H. pylori status, and further cagA status and vacA m and s genotypes by polymerase chain reaction. Patients were interviewed with structured questionnaires, and blood samples were collected for EPHX1, GSTM1, GSTT1, IL1B, IL1-RN, MTHFR and p53 genotyping. Proportions were compared in univariate analysis, while the relation between putative risk factors and H. pylori status and genotype were measured using logistic regression analysis. One hundred forty-nine gastric cancer patients were included, of which 78.5% were H. pylori positive. Among positive patients 50% were cagA+, 72.5% vacA m1 and 80.7% vacA s1. The presence of cagA was less frequent among vacA m1 (p = 0.031) and vacA s1 (p = 0.052) subtypes. The presence of father history for any cancer was a significant risk factor for H. pylori infection [adjusted odds ratio (OR) = 8.18, 95% confidence interval (CI) 1.04-64.55]. EPHX1 exon 3 T > C (OR = 0.35, CI 95% 0.13-0.94), IL1B-511 T > C (OR = 0.38, CI 95% 0.15-0.97) and IL1-RN VNTR (OR = 0.19, CI 95% 0.06-0.58) polymorphisms were protective towards H. pylori infection in the univariate analysis. Wine consumption was associated with higher risk of carrying the H. pylori vacA m1 virulent subtype (p = 0.034). Lastly, cardiovascular diseases were less common among cagA positive subjects (p = 0.023). Father history of any cancer is a risk factor for H. pylori infection. Polymorphisms in IL1B-511, IL1-RN and EPHX1 exon 3 genes might be protective towards H. pylori infection.

Martino A, Campa D, Jurczyszyn A, et al.
Genetic variants and multiple myeloma risk: IMMEnSE validation of the best reported associations--an extensive replication of the associations from the candidate gene era.
Cancer Epidemiol Biomarkers Prev. 2014; 23(4):670-4 [PubMed] Related Publications
BACKGROUND: Genetic background plays a role in multiple myeloma susceptibility. Several single-nucleotide polymorphisms (SNP) associated with genetic susceptibility to multiple myeloma were identified in the last years, but only a few of them were validated in independent studies.
METHODS: With the aim to conclusively validate the strongest associations so far reported, we selected the polymorphisms rs2227667 (SERPINE1), rs17501108 (HGF), rs3136685 (CCR7), rs16944 (IL1B), rs12147254 (TRAF3), rs1805087 (MTR), rs1800629 (TNF-α), rs7516435 (CASP9), rs1042265 (BAX), rs2234922 (mEH), and rs1801133 (MTHFR). We genotyped them in 1,498 multiple myeloma cases and 1,934 controls ascertained in the context of the International Multiple Myeloma rESEarch (IMMEnSE) consortium, and meta-analyzed our results with previously published ones.
RESULTS: None of the selected SNPs were significantly associated with multiple myeloma risk (P value range, 0.055-0.981), possibly with the exception of the SNP rs2227667 (SERPINE1) in women.
CONCLUSIONS: We can exclude that the selected polymorphisms are major multiple myeloma risk factors.
IMPACT: Independent validation studies are crucial to identify true genetic risk factors. Our large-scale study clarifies the role of previously published polymorphisms in multiple myeloma risk.

Sang Q, Li X, Wang H, et al.
Quantitative methylation level of the EPHX1 promoter in peripheral blood DNA is associated with polycystic ovary syndrome.
PLoS One. 2014; 9(2):e88013 [PubMed] Free Access to Full Article Related Publications
Steroid synthesis and metabolic pathways play important roles in the pathophysiology of PCOS, but until now there have been no studies on the methylation profiles of specific genes in steroid synthesis pathways that are known to be associated with PCOS. Here we used MassARRAY quantitative methylation analysis to determine the methylation levels of each CpG site or cluster in the promoters of EPHX1, SRD5A1, and CYP11A1 in 64 peripheral blood samples. We further examined the methylation level of EPHX1 in an independent cohort consisting of 116 people. Finally, we investigated the role of EPHX1 in steroidogenesis in the KGN cell line. For SRD5A1 and CYP11A1, there was no significant difference in methylation level between patients and controls. For EPHX1, however, the methylation levels of a few consecutive CpG sites and clusters were found to be significantly associated with PCOS. The methylation levels of a number of CpG clusters or sites were significantly lower in patients than in controls in the first cohort consisting of 64 people, such as clusters 13-14 (P<0.05), 15-16 (P<0.001), and 19-24 (P<0.001) and sites CpG_53 (P<0.01) and CpG_54 (P<0.05). Among differentiated methylation sites and clusters, the methylation levels of the CpG cluster 13-14 and CpG cluster 19-24 in PCOS patients were significantly lower than in controls in the second cohort of 116 people (P<0.05 for both). In addition, knockdown and overexpression experiments in KGN cells showed that EPHX1 can regulate estradiol concentrations, and this indicates a role for EPHX1 in steroidogenesis. Our study has demonstrated that methylation of the EPHX1 promoter might be associated with PCOS. This study provides direct evidence that methylation plays an important role in PCOS and demonstrates a novel role for EPHX1 in female reproduction.

Pérez-Morales R, Méndez-Ramírez I, Moreno-Macias H, et al.
Genetic susceptibility to lung cancer based on candidate genes in a sample from the Mexican Mestizo population: a case-control study.
Lung. 2014; 192(1):167-73 [PubMed] Related Publications
BACKGROUND: Lung cancer (LC) is the leading cause of mortality caused by neoplasias worldwide. Although cigarette smoking is the primary cause, not all smokers develop LC. Polymorphic variations in genes associated with carcinogen metabolism, DNA repair, and cell-cycle dysregulation may alter an individual risk of developing LC. A polygenic cancer model was proposed, which considers genetic susceptibility to cancer is a global mechanism and suggests that it might be defined by the contributions of low-risk alleles in several candidate genes. This study focused on the analysis of 15 polymorphisms in 12 low-penetrance genes in a case-control study of a sample of Mexican Mestizo population.
METHODS: A case-control study was performed with a total of 572 unrelated individuals, including 190 cases with a primary LC diagnosis and 382 healthy controls. The polymorphic status of the individuals was determined by TaqMan probe and RFLP techniques. The association between LC and genotype score (GS) was assessed by logistic regression.
RESULTS: The results suggests a protective effect of the genotypes Arg/Lys of AhR rs2066853 (odds ratio [OR] 0.55, p = 0.03), Ile/Val of CYP1A1 rs1048943 (OR 0.49, p = 0.009), Tyr/His of EPHX1 rs1051740 (OR 0.53, p = 0.03), and A/A of CCND1 rs603965 (OR 0.44, p = 0.02). Analyses using the GS suggest that average cases have a larger number of risk alleles than controls (Student's t test -4.85, p = 0.001; OR 1.25, p < 0.001).
CONCLUSIONS: Our results suggest significant differences between the GS for the cases and controls, which support the hypothesis underlying the additive and polygenic models for lung cancer risk depending on the polymorphisms in low-penetrance genes.

Barrington-Trimis JL, Searles Nielsen S, Preston-Martin S, et al.
Parental smoking and risk of childhood brain tumors by functional polymorphisms in polycyclic aromatic hydrocarbon metabolism genes.
PLoS One. 2013; 8(11):e79110 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: A recent meta-analysis suggested an association between exposure to paternal smoking during pregnancy and childhood brain tumor risk, but no studies have evaluated whether this association differs by polymorphisms in genes that metabolize tobacco-smoke chemicals.
METHODS: We assessed 9 functional polymorphisms in 6 genes that affect the metabolism of polycyclic aromatic hydrocarbons (PAH) to evaluate potential interactions with parental smoking during pregnancy in a population-based case-control study of childhood brain tumors. Cases (N = 202) were ≤10 years old, diagnosed from 1984-1991 and identified in three Surveillance, Epidemiology, and End Results (SEER) registries in the western U.S. Controls in the same regions (N = 286) were frequency matched by age, sex, and study center. DNA for genotyping was obtained from archived newborn dried blood spots.
RESULTS: We found positive interaction odds ratios (ORs) for both maternal and paternal smoking during pregnancy, EPHX1 H139R, and childhood brain tumors (P(interaction) = 0.02; 0.10), such that children with the high-risk (greater PAH activation) genotype were at a higher risk of brain tumors relative to children with the low-risk genotype when exposed to tobacco smoke during pregnancy. A dose-response pattern for paternal smoking was observed among children with the EPHX1 H139R high-risk genotype only (OR(no exposure) = 1.0; OR(≤3 hours/day) = 1.32, 95% CI: 0.52-3.34; OR(>3 hours/day )= 3.18, 95% CI: 0.92-11.0; P(trend )= 0.07).
CONCLUSION: Parental smoking during pregnancy may be a risk factor for childhood brain tumors among genetically susceptible children who more rapidly activate PAH in tobacco smoke.

Merlo DF, Agramunt S, Anna L, et al.
Micronuclei in cord blood lymphocytes and associations with biomarkers of exposure to carcinogens and hormonally active factors, gene polymorphisms, and gene expression: the NewGeneris cohort.
Environ Health Perspect. 2014; 122(2):193-200 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Leukemia incidence has increased in recent decades among European children, suggesting that early-life environmental exposures play an important role in disease development.
OBJECTIVES: We investigated the hypothesis that childhood susceptibility may increase as a result of in utero exposure to carcinogens and hormonally acting factors. Using cord blood samples from the NewGeneris cohort, we examined associations between a range of biomarkers of carcinogen exposure and hormonally acting factors with micronuclei (MN) frequency as a proxy measure of cancer risk. Associations with gene expression and genotype were also explored.
METHODS: DNA and protein adducts, gene expression profiles, circulating hormonally acting factors, and GWAS (genome-wide association study) data were investigated in relation to genomic damage measured by MN frequency in lymphocytes from 623 newborns enrolled between 2006 and 2010 across Europe.
RESULTS: Malondialdehyde DNA adducts (M1dG) were associated with increased MN frequency in binucleated lymphocytes (MNBN), and exposure to androgenic, estrogenic, and dioxin-like compounds was associated with MN frequency in mononucleated lymphocytes (MNMONO), although no monotonic exposure-outcome relationship was observed. Lower frequencies of MNBN were associated with a 1-unit increase expression of PDCD11, LATS2, TRIM13, CD28, SMC1A, IL7R, and NIPBL genes. Gene expression was significantly higher in association with the highest versus lowest category of bulky and M1dG-DNA adducts for five and six genes, respectively. Gene expression levels were significantly lower for 11 genes in association with the highest versus lowest category of plasma AR CALUX® (chemically activated luciferase expression for androgens) (8 genes), ERα CALUX® (for estrogens) (2 genes), and DR CALUX® (for dioxins). Several SNPs (single-nucleotide polymorphisms) on chromosome 11 near FOLH1 significantly modified associations between androgen activity and MNBN frequency. Polymorphisms in EPHX1/2 and CYP2E1 were associated with MNBN.
CONCLUSION: We measured in utero exposure to selected environmental carcinogens and circulating hormonally acting factors and detected associations with MN frequency in newborns circulating T lymphocytes. The results highlight mechanisms that may contribute to carcinogen-induced leukemia and require further research.

Hu JJ, Wang ZT, Li B
Meta-analysis demonstrates lack of an association of microsomal epoxide hydrolase 1 polymorphisms with esophageal cancer risk.
Genet Mol Res. 2013; 12(4):4540-8 [PubMed] Related Publications
Epoxide hydrolases metabolize exogenous chemicals, including carcinogens such as polycyclic aromatic hydrocarbons. The relationship between microsomal epoxide hydrolase 1 (EPHX1) polymorphisms and esophageal cancer risk has been investigated in various ethnic populations, but the results have been contradictory. We investigated the association of EPHX1 Tyr113His and His139Arg polymorphisms with esophageal cancer via a comprehensive meta-analysis. Publications before August 20, 2012 were included. Eight studies concerning Tyr113His polymorphism associated with 1158 esophageal cancer cases and 1868 controls were identified; 7 studies concerning association of His139Arg with 901 esophageal cancer cases and 1615 controls were also included. A random-effect model was applied, irrespective of between-study heterogeneity. Data and study quality were assessed in duplicate. No significant association was found in either the allele or genotype models for Tyr113His or His139Arg polymorphism with risk for esophageal cancer. Lack of association was also identified in stratified analyses by ethnicity. No publication bias was observed. We conclude that current evidence does not demonstrate association of EPHX1 Tyr113His or His139Arg polymorphisms with risk for development of esophageal cancer.

Duan CY, Liu MY, Li SB, et al.
Lack of association of EPHX1 gene polymorphisms with risk of hepatocellular carcinoma: a meta-analysis.
Tumour Biol. 2014; 35(1):659-66 [PubMed] Related Publications
Previous studies have focused on the association of a gene (EPHX1) encoding microsomal epoxide hydrolase with the carcinogenesis of hepatocellular carcinoma (HCC). In the present study, we performed a meta-analysis to systematically summarize the possible association between EPHX1 genetic polymorphisms and the risk for HCC. We conducted a search of case-control studies on the associations of EPHX1 genetic polymorphisms with susceptibility to HCC in PubMed, EMBASE, ISI Web of Science, Wanfang database in China, and the Chinese National Knowledge Infrastructure databases. Data from eligible studies were extracted for meta-analysis. HCC risk associated with EPHX1 genetic polymorphism was estimated by pooled odds ratios and 95% confidence intervals. Thirteen studies were included in the present meta-analysis. Our results showed that, for the two polymorphisms (337 T > C and 416A > G) of EPHX1 gene, neither allele frequency nor genotype distributions were associated with risk for HCC in all genetic models (all P > 0.05). This meta-analysis suggests that EPHX1 genetic polymorphisms were not associated with the risk of HCC.

Eom SY, Yim DH, Zhang Y, et al.
Dietary aflatoxin B1 intake, genetic polymorphisms of CYP1A2, CYP2E1, EPHX1, GSTM1, and GSTT1, and gastric cancer risk in Korean.
Cancer Causes Control. 2013; 24(11):1963-72 [PubMed] Related Publications
PURPOSE: We investigated the effects of aflatoxin B1 (AFB1) intake, genetic polymorphisms of AFB1 metabolic enzymes, and interactions between the polymorphisms and intake of AFB1 with regard to the risk of gastric cancer in Korean.
METHODS: The participants in the study included 477 gastric cancer patients and 477 age- and sex-matched control subjects. Direct interviews and a structured questionnaire were used to determine the level of exposure to AFB1, and the GoldenGate assay and multiplex polymerase chain reaction were used for genotypic analyses of the cytochrome P450 1A2 (CYP1A2), cytochrome P450 1E1, epoxide hydrolase 1, and glutathione S-transferase genes.
RESULTS: The probable daily intake of AFB1 was significantly higher among gastric cancer patients than among control subjects (cases vs. controls: 1.91 ± 0.87 vs. 1.65 ± 0.72 ng/kg bw/day, p < 0.0001), and increased AFB1 intake was significantly associated with an elevated risk of gastric cancer (odds ratio 1.94; 95 % confidence interval 1.43-2.63). However, genetic polymorphisms of AFB1 metabolic enzymes were not associated with gastric cancer, with the exception of CYP1A2. Moreover, there was no interaction between AFB1 intake and the genotypes of metabolic enzymes that affect gastric cancer risk.
CONCLUSIONS: Our results suggest that dietary AFB1 exposure might be associated with a risk of gastric cancer. However, the effect of AFB1 on gastric carcinogenesis may not be modulated by genetic polymorphisms of AFB1 metabolic enzymes.

Fathy M, Hamed M, Youssif O, et al.
Association between environmental tobacco smoke exposure and lung cancer susceptibility: modification by antioxidant enzyme genetic polymorphisms.
Mol Diagn Ther. 2014; 18(1):55-62 [PubMed] Related Publications
BACKGROUND: Environmental tobacco smoke (ETS) is the primary etiologic factor responsible for lung cancer. However, only 10-15 % of smokers develop lung cancer, suggesting a genetic role in modifying individual susceptibility to lung cancer. Antioxidant enzymes and genetic polymorphisms should be considered.
AIM: The present study aimed to evaluate the role of antioxidant enzyme activity and genetic polymorphisms in modifying the susceptibility to lung cancer among individuals exposed to ETS.
SUBJECTS AND METHODS: A total of 150 male subjects were divided into three groups: 50 lung cancer patients, 50 chronic smokers, and 50 passive smokers. Genotyping of microsomal epoxide hydrolase (mEH) exon 3 (Tyr(113)Hist) and exon 4 (Hist(139)Arg) polymorphisms were done by the polymerase chain reaction-restriction fragment length polymorphism technique. MnSOD (Val(16)Ala) polymorphism was detected by the real time-TaqMan assay. Erythrocyte MnSOD activity was measured spectrophotometrically.
RESULTS: ETS-exposed individuals (both active and passive smokers) who carried the His allele of mEH exon3 have a 2.9-fold increased risk of lung cancer (odds ratio [OR] 2.9, P < 0.001). In addition, ETS-exposed carriers of the Arg allele of mEH exon 4 have a 2.1-fold increased risk of lung cancer (OR 2.1, P = 0.024). However, no association between the MnSOD Val(16)Ala polymorphism and lung cancer was detected among ETS-exposed individuals (OR 1.6, P = 0.147), although the lung cancer group had significantly lower MnSOD activity than the chronic or passive smoker groups (P = 0.03).
CONCLUSIONS: Exons 3 and 4 polymorphisms of the mEH gene may contribute to lung cancer susceptibility through disturbed antioxidant balance. However, this was not the case with the MnSOD Val(16)Ala single-nucleotid polymorphism. Antioxidant enzymes may modulate the influence of ETS exposure on lung cancer risk.

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