Zheng Zhong, Fang Jia-Long, Lazarus Philip
Divisions of Cancer Control and Molecular Oncology, H. Lee Moffitt Cancer Center, Departments of Interdisciplinary Oncology, Biochemistry, and Pharmacology and Therapeutics, University of South Florida, Tampa, Florida 33612, USA.
Drug Metab Dispos. 2002 Apr;30(4):397-403. doi: 10.1124/dmd.30.4.397.
UDP-glucuronosyltransferases (UGTs) have been implicated as important detoxifying enzymes for several major tobacco carcinogens. Because the aerodigestive tract is a primary target for exposure to tobacco smoke carcinogens, the major goal of the present study was to determine whether aerodigestive tract tissues exhibit glucuronidating activity against metabolites of benzo[a]pyrene (BaP) and to explore the pattern of expression of UGT genes in a series of aerodigestive tract tissue specimens. Glucuronidation of the phenolic BaP metabolites 3-, 7-, and 9-hydroxy-BaP was observed in all upper aerodigestive tract tissue microsome specimens tested, as determined by high-pressure liquid chromatography analysis. Glucuronidating activity toward the procarcinogenic BaP metabolite trans-BaP-7,8-dihydrodiol(+/-) was also detected in aerodigestive tract tissues. By semiquantitative duplex reverse transcription-polymerase chain reaction analysis, UGT1A7 and UGT1A10 were shown to be well expressed in all aerodigestive tract tissues examined, including tongue, tonsil, floor of mouth, larynx, and esophagus. UGT1A8 and UGT1A6 were expressed primarily in larynx; no expression was observed for UGTs 1A1, 1A3, 1A4, 1A5, 1A9. Of the family 2B UGTs, only UGT2B4 and UGT2B17 exhibited significant levels of expression in aerodigestive tract tissues. Of the aerodigestive tract-expressing UGTs, only UGTs 1A7, 1A8, and 1A10 exhibited glucuronidating activity against 7-hydroxy-BaP, with UGT1A10 exhibiting the highest affinity as determined by kinetic analysis (K(m) = 49 microM). No UGT expression or glucuronidating activity was observed for any of the lung specimens analyzed in this study. These results suggest that several family 1 UGTs may potentially play an important role in BaP detoxification in the aerodigestive tract.
尿苷二磷酸葡萄糖醛酸基转移酶（UGTs）被认为是几种主要烟草致癌物的重要解毒酶。由于呼吸道和消化道是接触烟草烟雾致癌物的主要靶器官，本研究的主要目的是确定呼吸道和消化道组织是否对苯并[a]芘（BaP）代谢产物具有葡萄糖醛酸化活性，并探索一系列呼吸道和消化道组织标本中UGT基因的表达模式。通过高压液相色谱分析测定，在所测试的所有上呼吸道和消化道组织微粒体标本中均观察到了酚类BaP代谢产物3-、7-和9-羟基-BaP的葡萄糖醛酸化。在呼吸道和消化道组织中也检测到了对致癌前体BaP代谢产物反式-BaP-7,8-二氢二醇（+/-）的葡萄糖醛酸化活性。通过半定量双重逆转录-聚合酶链反应分析表明，UGT1A7和UGT1A10在所有检测的呼吸道和消化道组织中均有良好表达，包括舌、扁桃体、口腔底部、喉和食管。UGT1A8和UGT1A6主要在喉中表达；未观察到UGT 1A1、1A3、1A4、1A5、1A9的表达。在2B家族UGTs中，只有UGT2B4和UGT2B17在呼吸道和消化道组织中表现出显著的表达水平。在呼吸道和消化道表达的UGTs中，只有UGT 1A7、1A8和1A10对7-羟基-BaP具有葡萄糖醛酸化活性，通过动力学分析确定UGT1A10具有最高亲和力（K(m)=49 microM）。在本研究分析的任何肺标本中均未观察到UGT表达或葡萄糖醛酸化活性。这些结果表明，几种1家族UGTs可能在呼吸道和消化道中BaP的解毒过程中发挥重要作用。
