Effect of CYP3A5 expression on vincristine metabolism with human liver microsomes
Effect of CYP3A5 expression on vincristine metabolism with human liver microsomes
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DOI：
10.1124/jpet.106.118471
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发表时间：
2007-05-01
影响因子：
3.5
通讯作者：
Hall, Stephen D.
中科院分区：
文献类型：
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作者：
Dennison, Jennifer B.;Jones, David R.;Hall, Stephen D.
使用cDNA表达的酶，依普利汀通过CYP 3A 5优先代谢为仲胺M1，固有清除率比CYP 3A 4高9- 14倍。CYP 3A 5的遗传多态性表达可能导致长春新碱疗效和毒性的个体间变异性。本研究使用人肝微粒体（HLM）库定量了细胞色素P450（P450）（包括CYP 3A 4和CYP 3A 5）对长春新碱代谢的贡献。M1是HLM形成的主要代谢产物，P450的选择性化学抑制证实CYP 3A是主要代谢亚家族。对肝组织的低表达等位基因CYP 3A 5 * 3、* 6和 * 7进行基因分型，并通过蛋白质印迹法对HLM的CYP 3A 4和CYP 3A 5表达进行表型分型。使用替尼泊苷6 β-羟基化和伊曲康唑羟基化来定量HLM中的CYP 3A 4活性。对于各CYP 3A 5高表达者（n = 10），通过减去CYP 3A 5 *3/*3样品线性回归测定的CYP 3A 4贡献，定量测定CYP 3A 5导致的长春新碱M1形成速率。对于CYP 3A 5高表达者，CYP 3A 5对长春新碱代谢的贡献为总活性的54 - 95%，CYP 3A 5介导的M1形成速率与CYP 3A 5蛋白含量相关（r（2）= 0.95）。CYP 3A 4的选择性抑制表明，基于CYP 3A 4活性，CYP 3A 5高表达者的M1形成率受到差异性抑制。使用中位数，CYP 3A 5高表达者的估计肝脏清除率是低表达者的5倍。我们得出结论，CYP 3A 5的多态性表达可能是P450介导的长春新碱清除的主要决定因素。
Vincristine is preferentially metabolized to a secondary amine, M1, by CYP3A5 with a 9- to 14- fold higher intrinsic clearance than CYP3A4 using cDNA- expressed enzymes. The genetically polymorphic expression of CYP3A5 may contribute to interindividual variability in vincristine efficacy and toxicity. The current study quantifies the contribution of cytochromes P450 ( P450s), including CYP3A4 and CYP3A5, to vincristine metabolism with a bank of human liver microsomes ( HLMs). M1 was the major metabolite formed with HLMs, and selective chemical inhibition of P450s confirmed that CYP3A was the major metabolizing subfamily. The liver tissues were genotyped for low expression alleles, CYP3A5* 3,* 6, and * 7, and the HLMs were phenotyped for CYP3A4 and CYP3A5 expression by Western blot. Testosterone 6 beta- hydroxylation and itraconazole hydroxylation were used to quantify CYP3A4 activity in the HLMs. For each CYP3A5 high expresser ( n = 10), the rate of M1 formation from vincristine due to CYP3A5 was quantified by subtracting the CYP3A4 contribution as determined by linear regression with CYP3A5*3/*3 samples. For CYP3A5 high expressers, the contribution of CYP3A5 to the metabolism of vincristine was 54 to 95% of the total activity, and the rate of M1 formation mediated by CYP3A5 correlated with CYP3A5 protein content ( r(2) = 0.95). Selective inhibition of CYP3A4 demonstrated that the M1 formation rate with CYP3A5 high expressers was differentially inhibited based on CYP3A4 activity. Using median values, the estimated hepatic clearances were 5- fold higher for CYP3A5 high expressers than low expressers. We conclude that polymorphic expression of CYP3A5 may be a major determinant in the P450- mediated clearance of vincristine.