Cytochrome P450 3A4 mRNA Is a More Reliable Marker than CYP3A4 Activity for Detecting Pregnane X Receptor-Activated Induction of Drug-Metabolizing Enzymes
Cytochrome P450 3A4 mRNA Is a More Reliable Marker than CYP3A4 Activity for Detecting Pregnane X Receptor-Activated Induction of Drug-Metabolizing Enzymes
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DOI：
10.1124/dmd.110.033126
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发表时间：
2010-09-01
影响因子：
3.9
通讯作者：
Obach, R. Scott
中科院分区：
文献类型：
--
作者：
Fahmi, Odette A.;Kish, Mary;Obach, R. Scott
细胞色素P450（P450）活性在临床中的诱导可导致治疗失败，例如移植患者的组织排斥或意外怀孕等。CYP3A4是迄今为止最丰富的亚型，负责所有上市药物的大多数P450相关代谢。然而，重要的是要了解通过其他P450酶介导的诱导的意义。本研究的目的是使用冻存人肝细胞在体外评价几种已知诱导剂，旨在基于mRNA表达评估CYP 3A4、CYP 2B6、CYP 2C9、CYP 2C19和CYP 3A5的相关诱导。还基于三个不同批次的酶活性评估了CYP3A4诱导，以研究mRNA表达数据是否优于酶活性。一般而言，mRNA诱导倍数数据结果比活性数据更敏感，并且在药物也是P450抑制剂的情况下信息更丰富。每当CYP3A4 mRNA水平升高时，都会诱导其他药物代谢酶（包括CYP2B6和CYP2C酶）的转录，但程度较低，这表明CYP3A4 mRNA的测量是诱导这些其他酶的敏感标志物。甚至对于已知也通过组成型雄甾烷受体途径起作用的酶和诱导剂也是如此。最后，使用两种简单的二元分类方法检测了体外诱导测量在鉴定有临床意义的诱导剂中的效用：1）与溶媒对照相比的诱导倍数和2）相对于利福平的诱导反应。当使用基于相对于溶剂对照的诱导倍数的截止标准时，使用mRNA数据观察到最佳分类。
Induction of cytochrome P450 (P450) activity in the clinic can result in therapeutic failure such as tissue rejection in transplant patients or unwanted pregnancy, among others. CYP3A4 is by far the most abundant isoform and is responsible for the majority of P450-related metabolism of all marketed drugs. However, it is of importance to understand the significance of induction mediated through other P450 enzymes. The objective of this investigation was to evaluate several known inducers in vitro using cryopreserved human hepatocytes, with the aim of assessing the relevant induction of CYP3A4, CYP2B6, CYP2C9, CYP2C19, and CYP3A5, based on mRNA expression. CYP3A4 induction was also assessed based on enzymatic activity in three different lots to investigate whether mRNA expression data have any advantages over enzymatic activity. In general, the mRNA fold-induction data results were more sensitive compared with activity data, and more informative in cases in which the drug is also a P450 inhibitor. The induction of transcription of other drug-metabolizing enzymes including CYP2B6 and CYP2C enzymes occurred every time that CYP3A4 mRNA levels increased, but to a lesser extent, indicating that measurement of CYP3A4 mRNA is a sensitive marker for the induction of these other enzymes. This was the case even for enzymes and inducers that are known to also act via the constitutive androstane receptor pathway. Finally, the utility of in vitro induction measurements in the identification of clinically meaningful inducers was tested by using two simple binary classification approaches: 1) fold-induction versus vehicle control and 2) induction response relative to rifampin. The best classification was observed when the cutoff criteria based on fold induction relative to the vehicle control, using mRNA data are used.