title: Genetic polymorphisms of glutathione S-transferases M1 and T1 associated with susceptibility to aflatoxin-related hepatocarcinogenesis among chronic hepatitis B carriers: a nested case-control study in Taiwan.
abstract: This study was conducted to investigate the modifying effect of glutathione S-transferase (GST) M1 and T1 polymorphisms on aflatoxin-induced hepatocarcinogenesis among chronic hepatitis B virus surface antigen (HBsAg) carriers. A total of 79 HBsAg-positive cases of hepatocellular carcinoma (HCC) diagnosed between 1991 and 1997 were identified and individually matched to one or two HBsAg-positive controls on age, gender, residence and date of recruitment from the same cancer screening cohort in Taiwan. Blood samples were tested for hepatitis B and C viral markers by enzyme immunoassay and for aflatoxin B(1) (AFB(1))-albumin adducts by competitive enzyme-linked immunosorbent assay. GSTM1 and GSTT1 genotypes were determined by PCR. There was a statistically significant relationship between detectable levels of AFB(1)-albumin adducts in serum and risk of HCC among chronic HBsAg carriers, with an adjusted odds ratio (OR) of 2.0 [95% confidence interval (CI) 1.1-3.7]. In addition, the effect of aflatoxin exposure on HCC risk was more pronounced among chronic HBsAg carriers with the GSTT1 null genotype (OR 3.7, 95% CI 1.5-9.3) than those who were non-null (OR 0.9, 95% CI 0.3-2.4). The interaction between serum AFB(1)-albumin adduct level and GSTT1 genotype was statistically significant (P = 0.03). For GSTM1 the effect of aflatoxin exposure on HCC risk in those with the null genotype was also greater (adjusted OR 2.8, 95% CI 1.0-7.8) than in those with the gene present (adjusted OR 1.8, 95% CI 0.8-4.5), but the difference was not significant (P = 0.91). Notably, when the interaction between aflatoxin exposure and GSTT1 genotype was considered, aflatoxin exposure by itself was not a significant determinant of HCC risk among chronic HBsAg carriers. These results demonstrate the importance of gene-environment interactions in the multifactorial development of HCC.
authors.affiliation: School of Public Health, National Defense Medical Center, Taipei, Taiwan. sunca@ndmctsgh.edu.tw
authors.forename: C A
authors.initials: CA
authors.lastname: Sun
authors.forename: L Y
authors.initials: LY
authors.lastname: Wang
authors.forename: C J
authors.initials: CJ
authors.lastname: Chen
authors.forename: S N
authors.initials: SN
authors.lastname: Lu
authors.forename: S L
authors.initials: SL
authors.lastname: You
authors.forename: L W
authors.initials: LW
authors.lastname: Wang
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: D M
authors.initials: DM
authors.lastname: Wu
authors.forename: R M
authors.initials: RM
authors.lastname: Santella
mesh_terms: D000328:Adult; D016604:Aflatoxin B1 / Q000633:toxicity*; D002353:Carrier State; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005982:Glutathione Transferase / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000150:complications*; D006801:Humans; D008113:Liver Neoplasms / Q000139:chemically induced / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D013624:Taiwan / Q000453:epidemiology
chemical_list: D016604:Aflatoxin B1; D005982:Glutathione Transferase