Department of Chemical Biology and Therapeutics , St. Jude Children's Research Hospital , Memphis , Tennessee 38105-3678 , United States.
Integrated Biomedical Sciences Program , University of Tennessee Health Science Center , Memphis , Tennessee 38163 , United States.
J Med Chem. 2020 Feb 13;63(3):1415-1433. doi: 10.1021/acs.jmedchem.9b02067. Epub 2020 Jan 22.
The human cytochrome P450 (CYP) enzymes CYP3A4 and CYP3A5 metabolize most drugs and have high similarities in their structure and substrate preference. Whereas CYP3A4 is predominantly expressed in the liver, CYP3A5 is upregulated in cancer, contributing to drug resistance. Selective inhibitors of CYP3A5 are, therefore, critical to validating it as a therapeutic target. Here we report clobetasol propionate (clobetasol) as a potent and selective CYP3A5 inhibitor identified by high-throughput screening using enzymatic and cell-based assays. Molecular dynamics simulations suggest a close proximity of clobetasol to the heme in CYP3A5 but not in CYP3A4. UV-visible spectroscopy and electron paramagnetic resonance analyses confirmed the formation of an inhibitory type I heme-clobetasol complex in CYP3A5 but not in CYP3A4, thus explaining the CYP3A5 selectivity of clobetasol. Our results provide a structural basis for selective CYP3A5 inhibition, along with mechanistic insights, and highlight clobetasol as an important chemical tool for target validation.
人类细胞色素 P450（CYP）酶 CYP3A4 和 CYP3A5 代谢大多数药物，其结构和底物偏好具有高度相似性。虽然 CYP3A4 主要在肝脏中表达，但 CYP3A5 在癌症中上调，导致药物耐药性。因此，CYP3A5 的选择性抑制剂对于将其验证为治疗靶点至关重要。在这里，我们通过使用酶和基于细胞的测定的高通量筛选报告了丙酸氯倍他索（氯倍他索）作为一种有效的和选择性的 CYP3A5 抑制剂。分子动力学模拟表明，氯倍他索与 CYP3A5 中的血红素非常接近，但与 CYP3A4 中没有。紫外-可见光谱和电子顺磁共振分析证实了抑制型 I 血红素-氯倍他索复合物在 CYP3A5 中的形成，但在 CYP3A4 中没有，从而解释了氯倍他索对 CYP3A5 的选择性。我们的结果为选择性 CYP3A5 抑制提供了结构基础，同时也提供了机制见解，并强调了氯倍他索作为验证靶标的重要化学工具。
