title: Ketoconazole Stereoisomers Differentially Induce Cytochrome P450 1A1 Between Human Hepatoma HepG2 and Mouse Hepatoma Hepa1c1c7 Cells.
abstract: Ketoconazole (KTZ) has 2 chiral centers with the therapeutically active form being a racemic mixture of 2 cis-enantiomers, namely, (2R,4S)-(+)-KTZ and (2S,4R)-(-)-KTZ. The aims of the present study were to examine the effects of (+)-KTZ, (-)-KTZ, and (±)-KTZ on aryl hydrocarbon receptor activation and subsequently CYP1A1 induction in both human HepG2 and murine Hepa1c1c7 hepatoma cells, and to further test their inhibitory effect using recombinant human and mouse CYP1A1 enzymes. Our results demonstrated that (+)-KTZ induced human CYP1A1 more than (-)-KTZ, whereas on the other hand (-)-KTZ induced murine Cyp1a1 more than (+)-KTZ at the mRNA, and activity levels. Human CYP1A1 showed higher affinity to 7ER compared with murine Cyp1a1 (Km values 13.29 nM for human vs. 168.1 nM for murine). The intrinsic clearance values for human and murine CYP1A1 were 194.1 and 87.6 μL/pmol P450/min, respectively, whereas, Vmax values were 2.58 and 14.73 pmol/pmol P450/min, respectively. (+)-KTZ and (-)-KTZ directly inhibited CYP1A1 activity by noncompetitive mechanism. The affinity of (-)-KTZ to interact with human CYP1A1 and murine Cyp1a1 was significantly different from (+)-KTZ, as the Ki values for human CYP1A1 and murine Cyp1a1 were 199.4 and 413.7 nM, respectively, for (+)-KTZ, and 269.3 and 230.8 nM, respectively, for (-)-KTZ.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2N8, Canada; Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky 40202.
authors.forename: Anwar
authors.initials: A
authors.lastname: Anwar-Mohamed
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2N8, Canada.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: El-Sherbeni
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2N8, Canada; Faculty of Pharmacy, Alexandria University, Alexandria 21521, Egypt.
authors.forename: Dalia A
authors.initials: DA
authors.lastname: Hamdy
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2N8, Canada; Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Hesham M
authors.initials: HM
authors.lastname: Korashy
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2N8, Canada.
authors.forename: Dion R
authors.initials: DR
authors.lastname: Brocks
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2N8, Canada. Electronic address: aelkadi@pharmacy.ualberta.ca.
authors.forename: Ayman O S
authors.initials: AO
authors.lastname: El-Kadi
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism*; D045744:Cell Line, Tumor; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D007654:Ketoconazole / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000188:drug therapy / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D000935:Antifungal Agents; D012333:RNA, Messenger; D019363:Cytochrome P-450 CYP1A1; D007654:Ketoconazole
keywords: cytochrome P450; dose-response; drug metabolizing enzymes; enzyme kinetics; enzymes; hepatic clearance; hepatic metabolism; kinetics