Wang Hao, Dai Da-Peng, Sun Peng, Xu Li-Ping, Liang Bing-Qing, Cai Jian-Ping, Hu Guo-Xin
Department of Pharmacology, School of Pharmacy of Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, China.
Chem Biol Interact. 2017 Feb 25;264:10-15. doi: 10.1016/j.cbi.2017.01.003. Epub 2017 Jan 10.
Cytochrome P450 2D6 (CYP2D6) is an important member of the cytochrome P450 enzyme superfamily. We recently identified 22 novel variants in the Chinese population using PCR and bidirectional sequencing methods. The aim of this study is to characterize the enzymatic activity of these variants and their effects on the metabolism of the antimuscarinic drug tolterodine in vitro. A baculovirus-mediated expression system was used to express wild-type CYP2D6 and 24 variants (CYP2D62, CYP2D610, and 22 novel CYP2D6 variants) at high levels. The insect microsomes expressing CYP2D6 proteins were incubated with 0.1-50 μM tolterodine at 37 °C for 30 min and the metabolites were analyzed by high-performance liquid chromatography-tandem mass spectrometry system. Of the 24 CYP2D6 variants tested, 2 variants (CYP2D692 and CYP2D696) were found to be catalytically inactive, 4 variants (CYP2D694, F164L, F219S and D336N) exhibited markedly increased intrinsic clearance values (V/K) compared with the wild-type (from 66.34 to 99.79%), whereas 4 variants (CYP2D610, *93, *95 and E215K) exhibited significantly decreased values (from 49.02 to 98.50%). This is the first report of all these rare alleles for tolterodine metabolism and these findings suggest that more attention should be paid to subjects carrying these infrequent CYP2D6 alleles when administering tolterodine in the clinic.
细胞色素P450 2D6（CYP2D6）是细胞色素P450酶超家族的重要成员。我们最近使用聚合酶链反应（PCR）和双向测序方法在中国人群中鉴定出22种新的变异体。本研究的目的是表征这些变异体的酶活性及其对抗毒蕈碱药物托特罗定体外代谢的影响。采用杆状病毒介导的表达系统高水平表达野生型CYP2D6和24种变异体（CYP2D62、CYP2D610和22种新的CYP2D6变异体）。将表达CYP2D6蛋白的昆虫微粒体与0.1 - 50μM托特罗定在37℃孵育30分钟，并用高效液相色谱 - 串联质谱系统分析代谢产物。在所测试的24种CYP2D6变异体中，发现2种变异体（CYP2D692和CYP2D696）无催化活性，4种变异体（CYP2D694、F164L、F219S和D336N）与野生型相比，内在清除率值（V/K）显著增加（从66.34%至99.79%），而4种变异体（CYP2D610、*93、*95和E215K）的值显著降低（从49.02%至98.50%）。这是所有这些罕见等位基因对托特罗定代谢影响的首次报道，这些发现表明，在临床使用托特罗定时，应更多关注携带这些罕见CYP2D6等位基因的患者。
