Effects of Prototypical Microsomal Enzyme Inducers on Cytochrome P450 Expression in Cultured Human Hepatocytes

• DOI: 10.1124/dmd.31.4.421
• Publication Date: 2003-03-18T11:14:00Z
• Authors: Ajay Madan; Richard A. Graham; Kathleen M. Carroll; Daniel R. Mudra; L. Alayne Burton; Linda A. Krueger; April D. Downey; Maciej Czerwinski; Jameson Forster; Maria D. Ribadeneira; Liang-Shang Gan; Edward L. LeCluyse; Karl Zech; Philmore Robertson; Patrick Koch; Lida Antonian; Greg Wagner; Li Yu; Andrew Parkinson
• Keywords: Blotting, Western; Enzyme-Linked Immunosorbent Assay; Oxidoreductases, N-Demethylating; Mixed Function Oxygenases; 3. Good health; Cytochrome P-450 CYP2A6; Cytochrome P-450 CYP2C19; Cytochrome P-450 CYP2C8; Cytochrome P-450 CYP2B6; 03 medical and health sciences; 0302 clinical medicine; Cytochrome P-450 Enzyme System; Liver; Cytochrome P-450 CYP1A2; Enzyme Induction; Phenobarbital; Hepatocytes; Isoniazid; Cytochrome P-450 CYP3A; Humans; Aryl Hydrocarbon Hydroxylases; Enzyme Inhibitors; Cells, Cultured

Cultured human hepatocytes are a valuable in vitro system for evaluating new molecular entities as inducers of cytochrome P450 (P450) enzymes. The present study summarizes data obtained from 62 preparations of cultured human hepatocytes that were treated with vehicles (saline or dimethylsulfoxide, 0.1%), beta-naphthoflavone (33 microM), phenobarbital (100 or 250 microM), isoniazid (100 microM) and/or rifampin (20 or 50 microM), and examined for the expression of P450 enzymes based on microsomal activity toward marker substrates, or in the case of CYP2C8, the level of immunoreactive protein. The results show that CYP1A2 activity was markedly induced by beta-naphthoflavone (on average 13-fold, n = 28 preparations), and weakly induced by phenobarbital (1.9-fold, n = 25) and rifampin (2.3-fold, n = 22); CYP2A6 activity tended to be increased with phenobarbital (n = 7) and rifampin (n = 3) treatments, but the effects were not statistically significant; CYP2B6 was induced by phenobarbital (6.5-fold, n = 13) and rifampin (13-fold, n = 14); CYP2C8 was induced by phenobarbital (4.0-fold, n = 4) and rifampin (5.2-fold, n = 4); CYP2C9 was induced by phenobarbital (1.8-fold, n = 14) and rifampin (3.5-fold, n = 10); CYP2C19 was markedly induced by rifampin (37-fold, n = 10), but relatively modestly by phenobarbital (7-fold, n = 9); CYP2D6 was not significantly induced by phenobarbital (n = 5) or rifampin (n = 5); CYP2E1 was induced by phenobarbital (1.7-fold, n = 5), rifampin (2.2-fold, n = 5), and isoniazid (2.3-fold, n = 5); and, CYP3A4 was induced by phenobarbital (3.3-fold, n = 42) and rifampin (10-fold, n = 61), but not by beta-naphthoflavone. Based on these observations, we generalize that beta-naphthoflavone induces CYP1A2 and isoniazid induces CYP2E1, whereas rifampin and, to a lesser extent phenobarbital, tend to significantly and consistently induce enzymes of the CYP2A, CYP2B, CYP2C, CYP2E, and CYP3A subfamilies but not the 2D subfamily.