title: Characterization of UDP-glucuronosyltransferase 2A1 (UGT2A1) variants and their potential role in tobacco carcinogenesis.
abstract: OBJECTIVE
  To examine UGT2A1 expression in human tissues, determine its glucuronidation activity against tobacco carcinogens, and assess the potential functional role of UGT2A1 missense single nucleotide polymorphisms on UGT2A1 enzyme activity.
  
  
  METHODS
  Reverse transcription polymerase chain reaction and real time polymerase chain reaction were used to assess UGT2A1 gene expression in various human tissues. A glucuronidation assay measured by reverse phase ultra-performance liquid chromatography was used to determine UGT2A1 activity.
  
  
  RESULTS
  UGT2A1 was expressed in aerodigestive tract tissues including trachea, larynx, tonsil, lung, and colon; no expression was observed in breast, whole brain, pancreas, prostate, kidney, liver, or esophagus. UGT2A1 exhibited highest expression in the lung, followed by trachea >tonsil >larynx >colon >olfactory tissue. Cell homogenates prepared from wildtype UGT2A1(75Lys308Gly) overexpressing HEK293 cells showed significant glucuronidation activity against a variety of polycyclic aromatic hydrocarbons including, 1-hydroxy-benzo(a)pyrene, benzo(a)pyrene-7,8-diol, and 5-methylchrysene-1,2-diol. No activity was observed in UGT2A1 overexpressing cell homogenate against substrates that form N-glucuronides, such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), nicotine, or N-OH-2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (N-OH PhIP). A significant (P<0.05) decrease (approximately 25%) in glucuronidation activity (Vmax/KM) was observed against all polycyclic aromatic hydrocarbons substrates for the UGT2A1(75Lys308Gly) variant compared with homogenates from wildtype UGT2A1(75Lys308Gly); no activity was observed for cell homogenates overexpressing the UGT2A1 variant for all substrates tested.
  
  
  CONCLUSIONS
  These data suggest that UGT2A1 is an important detoxification enzyme in the metabolism of polycyclic aromatic hydrocarbons within target tissues for tobacco carcinogens and functional polymorphisms in UGT2A1 may play a role in tobacco-related cancer risk.
authors.affiliation: Molecular Epidemiology and Cancer Control Program, Penn State Cancer Institute, Department of Pharmacology, Penn State University College of Medicine, 500 University Drive, Hershey, Pennsylvania 17033, USA.
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Bushey
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Blevins-Primeau
authors.forename: Jacek
authors.initials: J
authors.lastname: Krzeminski
authors.forename: Shantu
authors.initials: S
authors.lastname: Amin
authors.forename: Philip
authors.initials: P
authors.lastname: Lazarus
mesh_terms: D000595:Amino Acid Sequence; D015153:Blotting, Western; D002273:Carcinogens / Q000378:metabolism; D002853:Chromatography, Liquid; D017124:Conserved Sequence / Q000235:genetics; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D020719:Glucuronides / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011230:Precancerous Conditions / Q000201:enzymology* / Q000235:genetics*; D013379:Substrate Specificity; D014026:Nicotiana / Q000009:adverse effects*
chemical_list: D002273:Carcinogens; D020719:Glucuronides; D011084:Polycyclic Aromatic Hydrocarbons; D014453:Glucuronosyltransferase