Promoter length polymorphism in UGT1A1 and the risk of sporadic colorectal cancer

Abstract

Uridine diphosphoglucuronate glucuronosyltransferase 1A1 (UGT1A1) is the key hepatic detoxification enzyme involved in the biotransformation of many carcinogens implicated in the development of colon, breast, and prostate cancers in humans. A polymorphism in the UGT1A1 promoter containing a TA-repeat element [(TA)5-8TAA] is involved in the modulation of UGT1A1 transcriptional activity. The wild-type activity is associated with the (TA)6TAA allele (UGT1A1*1), whereas UGT1A1 expression decreases with the increase of the TA-repeat number. We hypothesize that the low-activity allele UGT1A1*28 with seven TA repeats is associated with a higher risk for colorectal cancer. Our study involved 168 patients with histopathologically confirmed sporadic colorectal cancer and a control group of 96 individuals with no personal history of colorectal cancer. We detected a higher frequency of UGT1A1*28 than the wild-type UGT1A1*1 allele in colorectal cancer patients as compared with that of controls (odds ratio [OR] = 1.55, 95% confidence interval [CI] = 1.07-2.26, P = 0.021). The frequency of genotypes containing the UGT1A1*28 allele in the homozygous or heterozygous state was significantly higher than the frequency of the wild-type UGT1A1*1/*1 genotype in colorectal cancer patients as compared with controls (OR = 2.0, 95% CI = 1.19-3.34, P = 0.007). Our results indicate that the UGT1A1*28 allele is a risk factor for colorectal cancer in the Macedonian male population, whereas no significant risk was detected among women.