These results strongly suggest that NQO1 plays a significant role in preventing the development of colon cancer, and individuals with an NQO1 *2/*2 genotype are at an increased risk of developing this disease.
This observation may suggest a protective role of the NQO1 wild-type allele in colon cancer susceptibility of individuals exposed to NQO1-inducing chemicals.
RH1 was, correspondingly, more cytotoxic to human tumor cells expressing elevated NQO1 activity (H460 NSCLC and HT29 human colon carcinoma), as measured by 3-(4,5-dimethylthiazol-2,5-diphenyl)tetrazolium assay, than it was to cells deficient in NQO1 activity (H596 NSCLC and BE human colon carcinoma).
We studied 10 colon carcinoma cell lines showing different levels of DTD activity (range, 0-3447 nmol/min/mg protein), as measured by the reduction of dichlorophenolindophenol.