Genotype-phenotype correlation between the polymorphic UGT2B17 gene deletion and NNAL glucuronidation activities in human liver microsomes

Pharmacogenet Genomics. 2005 Nov;15(11):769-78. doi: 10.1097/01.fpc.0000175596.52443.ef.


The nicotine-derived tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is one of the most potent and abundant procarcinogens found in tobacco and tobacco smoke, and glucuronidation of its major metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), is an important mechanism for NNK detoxification. In cigarette smokers and tobacco chewers, there is a wide variation in the urinary levels of the ratio of NNAL to NNAL glucuronide (NNAL-Gluc). To determine whether genetic variation plays a potential role in this inter-individual variability, NNAL-glucuronidating activities were analysed in a series of human liver microsomal specimens and compared with UGT2B17 deletion genotypes in the same subjects. Assays performed in vitro demonstrated that over-expressed UGT2B17 exhibits high O-glucuronidating activity against NNAL. When stratifying subjects by UGT2B17 genotype, a significant or near-significant decrease in NNAL-O-Gluc formation was observed in liver microsomes from individuals who were either heterozygous [(+/0), P=0.07] or homozygous [(0/0), P=0.016] for the UGT2B17 deletion compared to liver microsomes from individuals with intact UGT2B17 alleles [(+/+)]. There was a significant (P<0.01) association between the level of liver microsomal NNAL-O-glucuronide formation and increasing numbers of the UGT2B17 null alleles in the liver microsomal specimens examined in this study, and a significant decrease in NNAL-O-Gluc formation was observed when comparing liver microsomes from individuals who had at least one UGT2B17 allele deleted [(+/0)+(0/0)] versus microsomes from UGT2B17 (+/+) subjects (P=0.004). When stratifying by the median value of NNAL-O-Gluc formation activity, a significantly (P=0.015) higher number of subjects with liver microsomes having low NNAL-O-Gluc formation activity contained the UGT2B17 null genotype compared to subjects with liver microsomes exhibiting high NNAL-O-Gluc formation activity. When stratifying by UGT2B7/UGT2B17 haplotypes, the association between the level of liver microsomal NNAL-O-glucuronide formation and increasing numbers of the UGT2B17 null allele was at the level of statistical significance for subjects with the UGT2B7 (*1/*2) (P=0.05) or UGT2B7 (*2/*2) (P<0.02) genotypes. These data suggest that the UGT2B17 deletion polymorphism is associated with a reduced rate of NNAL detoxification in vivo and may increase individual susceptibility to tobacco-related cancers.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Base Sequence
  • Carcinogens / metabolism
  • DNA / genetics
  • Gene Deletion
  • Genotype
  • Glucuronates / metabolism
  • Glucuronosyltransferase / genetics*
  • Glucuronosyltransferase / metabolism
  • Heterozygote
  • Homozygote
  • Humans
  • Inactivation, Metabolic
  • Microsomes, Liver / metabolism*
  • Minor Histocompatibility Antigens
  • Nicotiana
  • Nitrosamines / metabolism*
  • Pharmacogenetics
  • Phenotype
  • Polymorphism, Genetic
  • Pyridines / metabolism*
  • Smoke / analysis


  • 4-((methylnitrosoamino)-1-(3-pyridyl)but-1-yl)beta-omega-glucosiduronic acid
  • Carcinogens
  • Glucuronates
  • Minor Histocompatibility Antigens
  • Nitrosamines
  • Pyridines
  • Smoke
  • DNA
  • UGT2B7 protein, human
  • Glucuronosyltransferase
  • UGT2B17 protein, human
  • 4-(methylnitrosamino)-1-(3-pyridyl)-1-butan-1-ol