title: Elevated HPRT mutation frequencies in aflatoxin-exposed residents of daxin, Qidong county, People's Republic of China.
abstract: Molecular biomarkers are becoming increasingly important tools to identify people who are at highest risk of developing cancer. For many years we have been studying residents of Qidong County, People's Republic of China, to examine the combined impact of aflatoxin exposure with other risk factors as contributors to the high liver cancer incidence rates in this region. This study was conducted to determine the effects of aflatoxin exposure, as measured by serum aflatoxin-albumin adduct levels, on somatic mutation frequency in the human hypoxanthine guanine phosphoribosyl transferase gene (HPRT). Subjects were assigned as low or high according to a dichotomization around the population mean of aflatoxin-albumin adducts. HPRT mutant frequency was determined in individuals by a T cell clonal assay and the samples were categorized as low or high according to mean values. Separate analyses were also conducted for the small set of hepatitis B virus surface antigen (HBsAg)-positive and the larger set of HBsAg-negative individuals, known risk factors for liver cancer. An odds ratio of 19.3 (95% confidence interval 2.0, 183) was demonstrated for a high HPRT mutation frequency in individuals with high aflatoxin exposure compared with those with low aflatoxin exposure. This association indicates that aflatoxin-induced DNA damage in T lymphocytes, assessed using the validated surrogate albumin adduct markers, leads to increased mutations reflected as elevated HPRT gene mutations. This cross-sectional study suggests the potential use of mutation frequency of the HPRT gene as a long-term biomarker of aflatoxin exposure in high risk populations.
authors.affiliation: Department of Epidemiology and Department of Environmental Health Sciences, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Wang
authors.forename: J P
authors.initials: JP
authors.lastname: O'Neill
authors.forename: G S
authors.initials: GS
authors.lastname: Qian
authors.forename: Y R
authors.initials: YR
authors.lastname: Zhu
authors.forename: J B
authors.initials: JB
authors.lastname: Wang
authors.forename: H
authors.initials: H
authors.lastname: Armenian
authors.forename: A
authors.initials: A
authors.lastname: Zarba
authors.forename: J S
authors.initials: JS
authors.lastname: Wang
authors.forename: T W
authors.initials: TW
authors.lastname: Kensler
authors.forename: N F
authors.initials: NF
authors.lastname: Cariello
authors.forename: J D
authors.initials: JD
authors.lastname: Groopman
authors.forename: J A
authors.initials: JA
authors.lastname: Swenberg
mesh_terms: D000328:Adult; D016604:Aflatoxin B1 / Q000633:toxicity*; D000368:Aged; D002681:China; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation
chemical_list: D009153:Mutagens; D016604:Aflatoxin B1; D007041:Hypoxanthine Phosphoribosyltransferase