title: UDP-glucuronosyltransferase 1A10: activity against the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, and a potential role for a novel UGT1A10 promoter deletion polymorphism in cancer susceptibility.
abstract: The extrahepatic UDP-glucuronosyltransferase 1A10 (UGT1A10) is a phase II metabolizing enzyme that is active against a number of potent carcinogens. In the present study, UGT1A10 was examined for activity against 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), the major procarcinogenic metabolite of the potent tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, and the promoter region of UGT1A10 was examined for variants that could lead to altered UGT1A10 expression. UGT1A10-overexpressing cell homogenates exhibited high O-glucuronidation activity against NNAL (K(M) = 5.95 mM). A 2000-base pair (bp) product corresponding to the UGT1A10 proximal promoter region was polymerase chain reaction (PCR)-amplified using genomic DNA from 97 white subjects, and 42 of these were sequenced. In addition to a previously reported C/G single-nucleotide polymorphism at -1271 bp (rs2741032), a novel 1664-bp deletion located between nucleotides -190 to -1856 relative to the UGT1A10 translation start site was identified. Using real-time multiplex PCR, this deletion exhibited a prevalence of 0.022 in whites (n = 156) and 0.056 in blacks (n = 133). To determine whether either polymorphism altered gene expression, in vitro assays were performed using luciferase constructs containing up to 2000 bp of the proximal UGT1A10 promoter. Constructs containing the 1664-bp deletion exhibited a significant (p = 0.009) 3-fold increase in luciferase activity compared with constructs containing the wild-type UGT1A10 promoter. No effect on luciferase activity was observed for the UGT1A10(-1271G) promoter variant. These data are consistent with previous studies that indicate the presence of a transcriptional repressor element within the newly identified deletion and that this deletion polymorphism may contribute to altered UGT1A10 expression and altered carcinogen detoxification between individuals.
authors.affiliation: Population Sciences Program, Penn State Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA.
authors.forename: Rene M
authors.initials: RM
authors.lastname: Balliet
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Dellinger
authors.forename: Philip
authors.initials: P
authors.lastname: Lazarus
mesh_terms: D018938:Caco-2 Cells; D002273:Carcinogens / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000235:genetics* / Q000601:surgery; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D005787:Gene Frequency; D017930:Genes, Reporter; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease / Q000208:ethnology; D056914:Genomic Structural Variation; D014453:Glucuronosyltransferase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D008113:Liver Neoplasms / Q000201:enzymology / Q000235:genetics / Q000601:surgery; D050217:Metabolic Detoxication, Phase II / Q000235:genetics; D015778:Minor Histocompatibility Antigens; D009602:Nitrosamines / Q000378:metabolism*; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D011725:Pyridines / Q000378:metabolism*; D017384:Sequence Deletion / Q000235:genetics
chemical_list: D002273:Carcinogens; D007527:Isoenzymes; D015778:Minor Histocompatibility Antigens; D009602:Nitrosamines; D011725:Pyridines; C019787:bilirubin glucuronoside glucuronosyltransferase; C476725:bilirubin uridine-diphosphoglucuronosyl transferase 1A10; D014453:Glucuronosyltransferase; C500513:UGT2B17 protein, human; C099565:4-(methylnitrosamino)-1-(3-pyridyl)-1-butan-1-ol