title: Transcriptional control of intestinal cytochrome P-4503A by 1alpha,25-dihydroxy vitamin D3.
abstract: It was previously shown that CYP3A4 is induced in the human intestinal Caco-2 cell model by treatment with 1alpha,25-dihydroxy vitamin D3 (1,25-D3). We demonstrate the vitamin D analog, 19-nor-1alpha,25-dihydroxy vitamin D2, is also an effective inducer of CYP3A4 in Caco-2 cells, but with half the potency of 1,25-D3. We report that treatment of LS180 cells, a human intestinal cell line, with 1 to 10 nM 1,25-D3 dose dependently increased CYP3A4 protein and CYP3A4 mRNA expression. CYP3A4- and CYP3A23-promoter-Luciferase reporter constructs transiently transfected into LS180 cells were transcriptionally activated in a dose-dependent manner by 1,25-D3, whereas mutation of the nuclear hormone receptor binding motif (ER6) in the CYP3A4 promoter abrogated 1,25-D3 activation of CYP3A4. Although the CYP3A4 ER6 promoter element has been shown to bind the pregnane X receptor (PXR), this receptor does not mediate 1,25-D3 induction of CYP3A4 because a) PXR is not expressed in Caco-2 cells; b) PXR mRNA expression is not induced by 1,25-D3 treatment of LS180 cells; and c) the ligand binding domain of human PXR was not activated by 1,25-D3. 1,25-D3 uses the vitamin D receptor to induce CYP3A4 because a) the vitamin D receptor (VDR)-retinoid X receptor (RXR) heterodimer binds specifically to the CYP3A4 ER6; b) selective mutation of the CYP3A4 ER6 disrupted the binding of VDR-RXR; and c) reporter constructs containing only three copies of the CYP3A4 ER6 linked to a TK-CAT reporter were activated by 1,25-D3 only in cells cotransfected with a human VDR expression plasmid. These data support the hypothesis that 1,25-D3 and VDR induce expression of intestinal CYP3A by binding of the activated VDR-RXR heterodimer to the CYP3A PXR response element and promoting gene transcription.
authors.affiliation: Department of Pharmaceutics, University of Washington, Seattle, Washington, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Thummel
authors.forename: C
authors.initials: C
authors.lastname: Brimer
authors.forename: K
authors.initials: K
authors.lastname: Yasuda
authors.forename: J
authors.initials: J
authors.lastname: Thottassery
authors.forename: T
authors.initials: T
authors.lastname: Senn
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
authors.forename: H
authors.initials: H
authors.lastname: Ishizuka
authors.forename: E
authors.initials: E
authors.lastname: Kharasch
authors.forename: J
authors.initials: J
authors.lastname: Schuetz
authors.forename: E
authors.initials: E
authors.lastname: Schuetz
mesh_terms: D000818:Animals; D019556:COS Cells; D018938:Caco-2 Cells; D002117:Calcitriol / Q000494:pharmacology*; D002478:Cells, Cultured; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D004872:Ergocalciferols / Q000494:pharmacology; D000882:Haplorhini; D006801:Humans; D007422:Intestines / Q000187:drug effects* / Q000201:enzymology; D008156:Luciferases / Q000235:genetics; D006899:Mixed Function Oxygenases / Q000096:biosynthesis* / Q000235:genetics; D000077297:Pregnane X Receptor; D011485:Protein Binding; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism; D047488:Retinoid X Receptors; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation
chemical_list: D004872:Ergocalciferols; D000077297:Pregnane X Receptor; D018167:Receptors, Calcitriol; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D011987:Receptors, Steroid; D047488:Retinoid X Receptors; D014157:Transcription Factors; C084656:paricalcitol; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D008156:Luciferases; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D002117:Calcitriol