PT - JOURNAL ARTICLE AU - Luo, Gang AU - Cunningham, Mark AU - Kim, Sean AU - Burn, Tim AU - Lin, Jianrong AU - Sinz, Michael AU - Hamilton, Geraldine AU - Rizzo, Christopher AU - Jolley, Summer AU - Gilbert, Darryl AU - Downey, April AU - Mudra, Daniel AU - Graham, Richard AU - Carroll, Kathy AU - Xie, Jindong AU - Madan, Ajay AU - Parkinson, Andrew AU - Christ, Dave AU - Selling, Bernard AU - LeCluyse, Edward AU - Gan, Liang-Shang TI - CYP3A4 Induction by Drugs: Correlation between a Pregnane X Receptor Reporter Gene Assay and CYP3A4 Expression in Human Hepatocytes AID - 10.1124/dmd.30.7.795 DP - 2002 Jul 01 TA - Drug Metabolism and Disposition PG - 795--804 VI - 30 IP - 7 4099 - http://dmd.aspetjournals.org/content/30/7/795.short 4100 - http://dmd.aspetjournals.org/content/30/7/795.full SO - Drug Metab Dispos2002 Jul 01; 30 AB - Induction of cytochrome P450 3A4 (CYP3A4) is determined typically by employing primary culture of human hepatocytes and measuring CYP3A4 mRNA, protein and microsomal activity. Recently a pregnane X receptor (PXR) reporter gene assay was established to screen CYP3A4 inducers. To evaluate results from the PXR reporter gene assay with those from the aforementioned conventional assays, 14 drugs were evaluated for their ability to induce CYP3A4 and activate PXR. Sandwiched primary cultures of human hepatocytes from six donors were used and CYP3A4 activity was assessed by measuring microsomal testosterone 6β-hydroxylase activity. Hepatic CYP3A4 mRNA and protein levels were also analyzed using branched DNA technology/Northern blotting and Western blotting, respectively. In general, PXR activation correlated with the induction potential observed in human hepatocyte cultures. Clotrimazole, phenobarbital, rifampin, and sulfinpyrazone highly activated PXR and increased CYP3A4 activity; carbamazepine, dexamethasone, dexamethasone-t-butylacetate, phenytoin, sulfadimidine, and taxol weakly activated PXR and induced CYP3A4 activity, and methotrexate and probenecid showed no marked activation in either system. Ritonavir and troleandomycin showed marked PXR activation but no increase (in the case of troleandomycin) or a significant decrease (in the case of ritonavir) in microsomal CYP3A4 activity. It is concluded that the PXR reporter gene assay is a reliable and complementary method to assess the CYP3A4 induction potential of drugs and other xenobiotics. The American Society for Pharmacology and Experimental Therapeutics