The effect of cigarette smoke and arsenic exposure on urothelial carcinoma risk is modified by glutathione S-transferase M1 gene null genotype

Inter-individual variation in the metabolism of xenobiotics, caused by factors such as cigarette smoking or inorganic arsenic exposure, is hypothesized to be a susceptibility factor for urothelial carcinoma (UC). Therefore, our study aimed to evaluate the role of gene-environment interaction in the carcinogenesis of UC. A hospital-based case-control study was conducted. Urinary arsenic profiles were measured using high-performance liquid chromatography-hydride generator-atomic absorption spectrometry. Genotyping was performed using a polymerase chain reaction-restriction fragment length polymorphism technique. Information about cigarette smoking exposure was acquired from a lifestyle questionnaire. Multivariate logistic regression was applied to estimate the UC risk associated with certain risk factors. We found that UC patients had higher urinary levels of total arsenic, higher percentages of inorganic arsenic (InAs%) and monomethylarsonic acid (MMA%) and lower percentages of dimethylarsinic acid (DMA%) compared to controls. Subjects carrying the GSTM1 null genotype had significantly increased UC risk. However, no association was observed between gene polymorphisms of CYP1A1, EPHX1, SULT1A1 and GSTT1 and UC risk after adjustment for age and sex. Significant gene-environment interactions among urinary arsenic profile, cigarette smoking, and GSTM1 wild/null polymorphism and UC risk were observed after adjustment for potential risk factors. Overall, gene-environment interactions simultaneously played an important role in UC carcinogenesis. In the future, large-scale studies should be conducted using tag-SNPs of xenobiotic-metabolism-related enzymes for gene determination.