Lakehal F, Wendum D, Barbu V, Becquemont L, Poupon R, Balladur P, Hannoun L, Ballet F, Beaune P H, Housset C
Unité INSERM U402, Faculté de Médecine Saint-Antoine, Paris, France.
Hepatology. 1999 Dec;30(6):1498-506. doi: 10.1002/hep.510300619.
Tissue expression of drug-metabolizing enzymes influences susceptibility to drugs and carcinogens. Because the biliary epithelium, exposed to bile-borne chemicals, may give rise to drug-induced cholangiopathies and to cholangiocarcinomas, we determined the pattern of expression of drug-metabolizing enzymes in this epithelium. We first demonstrated by blot analyses that biliary epithelial cells (BEC) isolated from human gallbladders display cytochrome P450 (CYP) 1A, 2E1, and 3A, microsomal epoxide hydrolase (mEH), alpha, mu, and pi glutathione S-transferase (GST), transcripts and proteins. We also identified CYP-associated steroid 6beta-hydroxylase activity in BEC. CYP and mEH expression was 5- to 20-fold lower in BEC than in autologous hepatocytes, and further differed by a higher ratio of CYP3A5/CYP3A4, and by CYP1A1 predominance over CYP1A2. alphaGST was highly expressed in both hepatocytes and BEC, while piGST was restricted to BEC. In approximately 50% of individuals, muGST was expressed in hepatocytes and at lower levels in BEC. By using the same antibodies as those used in immunoblots, we could show by immunohistochemistry that CYP2E1, CYP3A, mEH, alpha, mu, and piGST immunoreactivities are expressed and display a heterogeneous distribution in the epithelium lining the entire biliary tract except for small intrahepatic bile ducts that were devoid of CYP3A and alphaGST immunoreactivities. In conclusion, BEC contribute to phase II, and although to a lesser extent than hepatocytes, to phase I biotransformation. The distribution of drug-metabolizing enzymes in BEC suggest that they are heterogeneous in their ability to generate and detoxicate reactive metabolites, which may contribute to specific distributions of cholangiopathies.
药物代谢酶的组织表达会影响对药物和致癌物的易感性。由于胆管上皮暴露于胆汁中的化学物质，可能引发药物性胆管病和胆管癌，因此我们确定了该上皮中药物代谢酶的表达模式。我们首先通过印迹分析证明，从人胆囊分离的胆管上皮细胞（BEC）显示细胞色素P450（CYP）1A、2E1和3A、微粒体环氧化物水解酶（mEH）、α、μ和π谷胱甘肽S-转移酶（GST）的转录本和蛋白质。我们还在BEC中鉴定出与CYP相关的类固醇6β-羟化酶活性。BEC中CYP和mEH的表达比自体肝细胞低5至20倍，并且进一步的差异在于CYP3A5/CYP3A4的比例更高，以及CYP1A1相对于CYP1A2占优势。αGST在肝细胞和BEC中均高表达，而πGST仅限于BEC。在大约50%的个体中，μGST在肝细胞中表达，在BEC中表达水平较低。通过使用与免疫印迹中相同的抗体，我们通过免疫组织化学表明，CYP2E1、CYP3A、mEH、α、μ和πGST免疫反应性在整个胆管内衬上皮中表达并呈现异质性分布，但小的肝内胆管除外，这些小胆管没有CYP3A和αGST免疫反应性。总之，BEC参与II相代谢，并且尽管程度小于肝细胞，但也参与I相生物转化。BEC中药物代谢酶的分布表明，它们在产生和解毒活性代谢物的能力方面是异质的，这可能导致胆管病的特定分布。
