Tsukada Chiharu, Saito Takahiro, Maekawa Masamitsu, Mano Nariyasu, Oda Akifumi, Hirasawa Noriyasu, Hiratsuka Masahiro
Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
Department of Pharmacy, Tohoku University Hospital, Sendai 980-8574, Japan.
Drug Metab Pharmacokinet. 2015 Oct;30(5):366-73. doi: 10.1016/j.dmpk.2015.07.003. Epub 2015 Jul 31.
Cytochrome P450 2C8 (CYP2C8) is one of the enzymes primarily responsible for the metabolism of many drugs, including paclitaxel and amodiaquine. CYP2C8 genetic variants contribute to interindividual variations in the therapeutic efficacy and toxicity of paclitaxel. Although it is difficult to investigate the enzymatic function of most CYP2C8 variants in vivo, this can be investigated in vitro using recombinant CYP2C8 protein variants. The present study used paclitaxel to evaluate 6α-hydroxylase activity and amodiaquine for the N-deethylase activity of wild-type and 11 CYP2C8 variants resulting in amino acid substitutions in vitro. The wild-type and variant CYP2C8 proteins were heterologously expressed in COS-7 cells. Paclitaxel 6α-hydroxylation and amodiaquine N-deethylation activities were determined by measuring the concentrations of 6α-hydroxypaclitaxel and N-desethylamodiaquine, respectively, and the kinetic parameters were calculated. Compared to the wild-type enzyme (CYP2C8.1), CYP2C8.11 and CYP2C8.14 showed little or no activity with either substrate. In addition, the intrinsic clearance values of CYP2C8.8 and CYP2C8.13 for paclitaxel were 68% and 67% that of CYP2C8.1, respectively. In contrast, the CLint values of CYP2C8.2 and CYP2C8.12 were 1.4 and 1.9 times higher than that of CYP2C8.1. These comprehensive findings could inform for further genotype-phenotype studies on interindividual differences in CYP2C8-mediated drug metabolism.
细胞色素P450 2C8（CYP2C8）是主要负责许多药物代谢的酶之一，包括紫杉醇和阿莫地喹。CYP2C8基因变异导致紫杉醇治疗效果和毒性的个体差异。虽然很难在体内研究大多数CYP2C8变异体的酶功能，但可以使用重组CYP2C8蛋白变异体在体外进行研究。本研究使用紫杉醇评估6α-羟化酶活性，使用阿莫地喹评估野生型和11种导致氨基酸替代的CYP2C8变异体的N-脱乙基酶活性。野生型和变异型CYP2C8蛋白在COS-7细胞中异源表达。通过分别测量6α-羟基紫杉醇和N-去乙基阿莫地喹的浓度来确定紫杉醇6α-羟化和阿莫地喹N-脱乙基活性，并计算动力学参数。与野生型酶（CYP2C8.1）相比，CYP2C8.11和CYP2C8.14对两种底物的活性都很低或没有活性。此外，CYP2C8.8和CYP2C8.13对紫杉醇的内在清除率值分别为CYP2C8.1的68%和67%。相反，CYP2C8.2和CYP2C8.12的CLint值分别比CYP2C8.1高1.4倍和1.9倍。这些全面的研究结果可为进一步开展关于CYP2C8介导的药物代谢个体差异的基因型-表型研究提供参考。
