Cytochrome b5 Is a Major Determinant of Human Cytochrome P450 CYP2D6 and CYP3A4 Activity In Vivo
Cytochrome b5 Is a Major Determinant of Human Cytochrome P450 CYP2D6 and CYP3A4 Activity In Vivo
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DOI：
10.1124/mol.114.097394
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发表时间：
2015-04-01
影响因子：
3.6
通讯作者：
Wolf, C. Roland
中科院分区：
文献类型：
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作者：
Henderson, Colin J.;McLaughlin, Lesley A.;Wolf, C. Roland
依赖于细胞色素P450的单加氧酶系统负责化学预防药物、化学毒素和致癌物的代谢和处置，以及80%的治疗药物。细胞色素P450(P450)活性受转录和P450还原酶电子传递速率的调节。体外研究表明，细胞色素b(5)(Cyb5)也调节P450的功能。我们最近发现，小鼠(HBN)肝脏中Cyb5的缺失显著改变了体内药物的药代动力学；一个关键的悬而未决的问题是，Cyb5是否调节体内药物处置中主要的人类P450的活性。为了解决这个问题，我们将携带CYP2D6或CYP3A4的人源化小鼠与携带肝脏Cyb5缺失的小鼠进行了杂交。在体外，CYP3A4-HBN小鼠肝微粒体中的三唑仑4-羟基化(以CYP3A4为探针反应)与对照组相比减少了50%。用CYP2D6-HBN微体观察到Debrisquine 4-羟化和美托洛尔α-羟化作用类似的减少，表明Cyb5在这两种酶的活性中都起着重要作用。这一效应通过浓度依赖性地恢复了CYP3A4介导的三唑仑转运和CYP2D6介导的呋喃西林和脱氢异喹的转运对含有重组Cyb5的大肠杆菌膜的添加而得到证实。在体内，三唑仑在0~8h(AUC(0~8h))的血药浓度峰值和血药浓度时间曲线下面积分别增加了4倍和5.7倍。同样，在CYP2D6-HBN小鼠体内，呋喃西林和脱氢异喹的药代动力学也发生了显著变化，AUC(0-8h)增加了1.5倍，清除量减少了40-60%。这些数据表明，Cyb5可能是体内CYP3A4和CYP2D6活性的主要决定因素，对许多治疗药物的新陈代谢、疗效和副作用具有潜在的影响。
The cytochrome P450-dependent mono-oxygenase system is responsible for the metabolism and disposition of chemopreventive agents, chemical toxins and carcinogens, and >80% of therapeutic drugs. Cytochrome P450 (P450) activity is regulated transcriptionally and by the rate of electron transfer from P450 reductase. In vitro studies have demonstrated that cytochrome b(5) (Cyb5) also modulates P450 function. We recently showed that hepatic deletion of Cyb5 in the mouse (HBN) markedly alters in vivo drug pharmacokinetics; a key outstanding question is whether Cyb5 modulates the activity of the major human P450s in drug disposition in vivo. To address this, we crossed mice humanized for CYP2D6 or CYP3A4 with mice carrying a hepatic Cyb5 deletion. In vitro triazolam 4-hydroxylation (probe reaction for CYP3A4) was reduced by >50% in hepatic microsomes from CYP3A4-HBN mice compared with controls. Similar reductions in debrisoquine 4-hydroxylation and metoprolol alpha-hydroxylation were observed using CYP2D6-HBN microsomes, indicating a significant role for Cyb5 in the activity of both enzymes. This effect was confirmed by the concentration-dependent restoration of CYP3A4-mediated triazolam turnover and CYP2D6-mediated bufuralol and debrisoquine turnover on addition of Escherichia coli membranes containing recombinant Cyb5. In vivo, the peak plasma concentration and area under the concentration time curve from 0 to 8 hours (AUC(0-8 h)) of triazolam were increased 4- and 5.7-fold, respectively, in CYP3A4-HBN mice. Similarly, the pharmacokinetics of bufuralol and debrisoquine were significantly altered in CYP2D6-HBN mice, the AUC(0-8 h) being increased similar to 1.5-fold and clearance decreased by 40-60%. These data demonstrate that Cyb5 can be a major determinant of CYP3A4 and CYP2D6 activity in vivo, with a potential impact on the metabolism, efficacy, and side effects of numerous therapeutic drugs.