Glucuronidation of nicotine and cotinine by UGT2B10:: Loss of function by the UGT2B10 codon 67 (Asp>Tyr) polymorphism
Glucuronidation of nicotine and cotinine by UGT2B10:: Loss of function by the UGT2B10 codon 67 (Asp>Tyr) polymorphism
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DOI：
10.1158/0008-5472.can-07-2245
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发表时间：
2007-10-01
期刊：
影响因子：
11.2
通讯作者：
Lazarus, Philip
中科院分区：
文献类型：
--
作者：
Chen, Gang;Blevins-Primeau, Andrea S.;Lazarus, Philip
尼古丁是烟草和烟草烟雾中的主要致瘾剂，其代谢途径复杂，约22%的尼古丁尿代谢产物以11相n -糖醛酸化合物的形式存在。最近的研究表明，UGT2B10是参与几种烟草特异性亚硝胺的n -葡萄糖醛酸化的主要酶。在本研究中，ugt2b10过表达的HEK293细胞的微粒体对尼古丁和可替宁均表现出较高的n -糖醛酸化活性，其表观Km值分别比ugt1a4过表达细胞的微粒体对尼古丁和可替宁的表观Km值低37倍和3倍。野生型（WT） ugt2b10过表达细胞对尼古丁和可替宁的微粒体的Km与人肝微粒体（HIM）对这两种底物的Km相似。112例HLM样本中糖醛酸化尼古丁或可替宁水平与UGT2B10基因型相关；UGT2B10（*1/*2）基因型与WT型UGT2B10基因型相比，UGT2B10样本中尼古丁和可替宁葡萄糖醛酸盐水平低21% ~ 30%；UGT2B10（*2/*2）基因型受试者在HIM中分别观察到尼古丁和可替宁-葡萄糖醛酸形成水平低5倍和16倍。与在体外过表达UGT2B10的细胞中观察到的相对较高的活性相反，从过表达UGT2B10*2变体的细胞中观察到的微粒体对尼古丁或可替宁的糖醛酸化作用很少或没有。这些数据表明，UGT2B10是参与尼古丁/可替宁糖醛酸化的主要肝脏酶，UGT2B10*2变异显著减少尼古丁和可替宁- n糖醛酸化的形成，在尼古丁代谢和消除中发挥重要作用。
Nicotine, the major addicting agent in tobacco and tobacco smoke, undergoes a complex metabolic pathway, with similar to 22% of nicotine urinary metabolites in the form of phase 11 N-glucuronidated compounds. Recent studies have shown that UGT2B10 is a major enzyme involved in the N-glucuronidation of several tobacco-specific nitrosamines. In the present study, microsomes of UGT2B10-overexpressing HEK293 cells exhibited high N-glucuronidation activity against both nicotine and cotinine with apparent Km's that were 37- and 3-fold lower than that observed for microsomes of UGT1A4-overexpressing cells against nicotine and cotinine, respectively. The Km of microsomes from wild-type (WT) UGT2B10-overexpressing cells for nicotine and cotinine was similar to that observed for human liver microsomes (HIM) against both substrates. The level of glucuronidated nicotine or cotinine in 112 HLM samples was correlated with UGT2B10 genotype; the levels of nicotine- and cotinine-glucuronide were 21% to 30% lower in specimens from subjects with the UGT2B10 (*1/*2) genotype compared with specimens from subjects with the WT UGT2B10 genotype; a 5- and 16-fold lower level of nicotine- and cotinine-glucuronide formation, respectively, was observed in HIM from subjects with the UGT2B10 (*2/*2) genotype. In contrast to the relatively high activity observed for cells overexpressing WT UGT2B10 in vitro, little or no glucuronidation was observed for microsomes from cells overexpressing the UGT2B10*2 variant against either nicotine or cotinine. These data suggest that UGT2B10 is the major hepatic enzyme involved in nicotine/cotinine glucuronidation and that the UGT2B10*2 variant significantly reduces nicotine- and cotinine-N-glucuronidation formation and plays an important role in nicotine metabolism and elimination.