title: Regulation of CYP2C19 expression by estrogen receptor α: implications for estrogen-dependent inhibition of drug metabolism.
abstract: Cytochrome P4502C19 (CYP2C19) is an important drug-metabolizing enzyme involved in the biotransformation of, for example, proton pump inhibitors and antidepressants. Several in vivo studies have shown that the CYP2C19 activity is inhibited by oral contraceptives, which can cause important drug interactions. The underlying molecular mechanism has been suggested to be competitive inhibition. However, the results presented here indicate that estradiol derivatives down-regulate CYP2C19 expression via estrogen receptor (ER) α, which interacts with the newly identified ER-binding half site [estrogen response element (ERE)] at the position -151/-147 in the CYP2C19 promoter. In gene reporter experiments in Huh-7 hepatoma cells, the activity of the luciferase construct carrying a 1.6-kb long CYP2C19 promoter fragment cotransfected with ERα was down-regulated upon treatment with 17β-estradiol (EE) or 17α-ethinylestradiol (ETE) at half-maximum concentrations of 10(-7) and 10(-8) M, respectively. Mutations introduced into the ERE half site -151/-147 significantly inhibited these ligand-dependent effects. Electrophoretic mobility shift assays and quantitative chromatin immunoprecipitation experiments revealed that estrogen receptor α binds to this element. A significant suppression of CYP2C19 transcription by female sex steroids was confirmed by reverse transcription polymerase chain reaction after hormonal treatment of human hepatocytes. Inhibition experiments using a stable human embryonic kidney 293 CYP2C19 cell line revealed competitive inhibition at much higher concentrations of EE and ETE compared with those required for transcriptional inhibition. These results indicate that both EE and ETE inhibit CYP2C19 expression via an ERα-dependent regulatory pathway, thus providing a new insight into the molecular mechanism behind the inhibitory effect of oral contraceptives on CYP2C19 activity.
authors.affiliation: Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Jessica
authors.initials: J
authors.lastname: Mwinyi
authors.forename: Isa
authors.initials: I
authors.lastname: Cavaco
authors.forename: Rasmus Steen
authors.initials: RS
authors.lastname: Pedersen
authors.forename: Anna
authors.initials: A
authors.lastname: Persson
authors.forename: Sabrina
authors.initials: S
authors.lastname: Burkhardt
authors.forename: Souren
authors.initials: S
authors.lastname: Mkrtchian
authors.forename: Magnus
authors.initials: M
authors.lastname: Ingelman-Sundberg
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D001665:Binding Sites; D002478:Cells, Cultured; D003278:Contraceptives, Oral, Hormonal / Q000494:pharmacology*; D065731:Cytochrome P-450 CYP2C19; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000502:physiology*; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D020218:Response Elements; D015533:Transcriptional Activation
chemical_list: D003278:Contraceptives, Oral, Hormonal; D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D004997:Ethinyl Estradiol; D004958:Estradiol; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19