Metabolic differences and their impact on human disease Sulfotransferase and colorectal cancer.

Gene-environment interaction is an important aspect of human cancer risk. Genetic polymorphisms in acetylation and N-oxidation have previously been described regarding their impact on the heterocyclic amine-induced risk for colon cancer. Here, we report that another enzyme involved in the metabolism of food-borne carcinogens, sulfotransferase (ST1A3 measured by 2-naphthol activity), may function as a potential protective factor for colon cancer in humans. Initially characterized in human liver and colon (Chou et al., 1995), TS-PST activity can also be measured in platelets. A simple microtiter-based colorimetric technique was developed for use in this case-control study. African-Americans had a higher mean ST activity than Caucasians (2.32±0.24 versus 1.77±0.09 nmols/min per mg cytosolic protein, P=0.036). Furthermore, the slow ST phenotype (ST≤1.53) was more frequently associated with colon cancer than controls (57 versus 40%, P=0.026). These data suggest that the ST1A3 isoform may play a role in the differential risk for colorectal cancer.