Identification of a prevalent functional missense polymorphism in the UGT2B10 gene and its association with UGT2B10 inactivation against tobacco-specific nitrosamines

摘要

Objective To study the potential association between UDP-glucuronosyltransferase (UGT)2B10 genotypes and [4-(methylnitrosamino)-1 -(3-pyridyl)-1 -butanol] NNAL-A/-glucuronidation activity in human liver microsomes (HLM) and to identify potential functional polymorphisms.Methods A total of 77 subjects were genotyped for three UGT2B10 tagging single nucleotide polymorphisms NNAL-/V-glucuronidation activity in HLM was determined by high-pressure liquid chromatography and analyzed by UGT2B10 haplotypes.Results Four common UGT2B10 haplotypes (termed A through D) were identified. Haplotype C was found to be significantly (P< 0.001) associated with lower NNAL-A/-glucuronidation in HLM. A 1.8-fold and 12-fold reduction in NNAL-A/-glucuronidation levels and a 1.7-fold and 11-fold reduction in the ratio of NNAL-A/-Gluc: NNAL-O-Gluc, were observed in HLM from subjects with one and two copies of UGT2B10 haplotype C, respectively. A novel polymorphism resulting in an aspartic acid to tyrosine amino acid change at codon 67 of the UGT2B10 complementary DNA was identified exclusively in subjects with a haplotype C. Unlike the high activity observed in microsomes from HEK293 cells over expressing the wild-type UGT2B10~(67Asp) variant, microsomes from HEK293 cells over expressing the UGT2B10~(67Asp) variant exhibited minimal glucuronide formation activity against NNAL or other tobacco-specific nitrosamines tested in vitro.Conclusions The UGT2B1 o~(67Asp)r variant corresponding to the UGT2B10 haplotype C is a functional single nucleotide polymorphism that may be responsible for inter individual variation in NNAL-N-glucuronidation activity and may increase susceptibility to smoking-related cancers.