The polymorphisms of GSTM1, GSTT1, HYL1*2, and XRCC1, and aflatoxin B1-related hepatocellular carcinoma in Guangxi population, China.

OBJECTIVE

High incidence rates of hepatocellular carcinoma (HCC) in Guangxi, China, are primarily due to heavy aflatoxin B1 (AFB1) exposure via corn and groundnut consumption. This study was designed to examine the polymorphisms associated of three carcinogen-metabolizing genes (namely: GSTM1, GSTT1, and HYL1*2) and one DNA-repair gene (namely: XRCC1), and investigate their role as susceptibility markers for HCC.

METHODS

We conducted a case-control study including 257 cases of cancer and 649 hospital-based age, sex, ethnicity, and hepatitis B virus infection-matched controls to examine the role of genetic polymorphisms of four genes (GSTM1, GSTT1, HYL1*2, and XRCC1) in the context of HCC risk for the Guangxi population. Genomic DNA isolated from 2ml whole blood was used to genotype GSTM1, GSTT1, HYL1*2, and XRCC1 by means of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis.

RESULTS

GSTT1-null genotype was not significantly associated with the risk of HCC, but GSTM1-null genotype [adjusted odds ratio (OR)=2.29, 95% confidence interval (CI)=1.59-3.31], HYL1*2 genotypes with 113 His allele (namely: YH/HH, adjusted OR=2.55, CI=1.78-3.65), and XRCC1 genotypes with 399 Gln allele (namely: AG/GG, adjusted OR=2.47, CI=1.72-3.54) increased the HCC risk. Compared with those individuals who did not express any putative risk genotypes as reference (OR=1), individuals featuring all of the putative risk genotypes [GSTM1-null, HYL1*2-YH/HH, and XRCC1-AG/GG] did experience a significantly greater cancer risk (adjusted OR=10.83, CI=5.44-21.59, P(interaction)<0.01). Additionally, the risk of HCC did appear to differ more significantly among individuals featuring risk genotypes and high-level or long-term AFB1 exposure, whose adjusted ORs (CIs) were 52.44 (17.51-157.08) and 326.93 (38.58-2770.52), respectively.

CONCLUSIONS

The results suggest that carcinogen metabolism and DNA-repair pathways may simultaneously modulate the risk of HCC for Guangxi population, and, particularly for these having high-level or long-term AFB1 exposure.