Metabolic Profile, Enzyme Kinetics, and Reaction Phenotyping of β-Lapachone Metabolism in Human Liver and Intestine in Vitro
Metabolic Profile, Enzyme Kinetics, and Reaction Phenotyping of β-Lapachone Metabolism in Human Liver and Intestine in Vitro
复制标题
DOI：
10.1021/mp300296m
复制
发表时间：
2012-12-01
影响因子：
4.9
通讯作者：
Hao, Haiping
中科院分区：
文献类型：
--
作者：
Cheng, Xuefang;Liu, Fang;Hao, Haiping
β - lapachone （β - lap）是一种NAD(P)H：醌氧化还原酶1 （NQO1）靶向抗肿瘤药物，处于II期临床试验中。本研究旨在揭示β - lap在体外人肝脏和肠道代谢的代谢谱、酶动力学和酶同工型。nqo1介导的醌还原和随后的葡萄糖醛酸化是人类β - lap的主要代谢途径；还原β - lap - glucuronides的一对区域异构体（M1和M2）是人类S9培养中发现的主要代谢物。β - lap在人肝脏S9的糖醛酸化总清除率为4754.90 μ L/min/mg蛋白，是人肠道S9的8.1倍。通过重组UDP-glucuronosyltransferase （UGT）筛选、相关分析、酶动力学和化学抑制研究来确定UGT亚型参与β - lap代谢。UGT1A7、UGT1A8和UGT1A9是M2形成的主要异构体，而UGT2B7是M1形成的主要异构体，这表明UGTs对还原的醌进行了区域选择性葡萄糖醛酸化。有趣的是，我们发现β - lap发生了非酶促双电子还原，这为β - lap在高浓度和长时间孵育下对nqo1阴性细胞的毒性提供了新的解释。总之，这项研究不仅有助于更好地了解β - lap代谢，而且有助于了解其抗肿瘤特性。
beta-Lapachone (beta-Lap) is an NAD(P)H:quinone oxidoreductase 1 (NQO1) target antitumor drug candidate in phase II clinical trials. The present study aimed to uncover the metabolic profile, enzyme kinetics, and enzyme isoforms for the metabolism of beta-Lap in human liver and intestine in vitro. NQO1-mediated quinone reduction and subsequent glucuronidation is the predominant metabolic pathway for beta-Lap in humans; a pair of regioisomers (M1 and M2) of reduced beta-Lap glucuronides were the major metabolites found from human S9 incubations. The overall glucuronidation clearance of beta-Lap in human liver S9 was 4754.90 mu L/min/mg of protein and was 8.1-fold of that in human intestinal S9. Recombinant UDP-glucuronosyltransferase (UGT) screening, correlation analysis, enzyme kinetics, and chemical inhibition study were performed to determine the UGT isoforms involved in beta-Lap metabolism. UGT1A7, UGT1A8, and UGT1A9 are the predominant isoforms responsible for the formation of M2 while UGT2B7 is the main isoform for M1, suggesting a regioselective glucuronidation of reduced quinone by UGTs. It was of interest to find that beta-Lap underwent nonenzymatic two-electron reduction, providing a novel explanation for the toxicities of beta-Lap to NQO1-negative cells at high concentration and with long-time incubation. In conclusion, this study contributes to a better understanding of not only beta-Lap metabolism but its antitumor property as well.