title: The PREgnane X receptor gene-humanized mouse: a model for investigating drug-drug interactions mediated by cytochromes P450 3A.
abstract: The most common clinical implication for the activation of the human pregnane X receptor (PXR) is the occurrence of drug-drug interactions mediated by up-regulated cytochromes P450 3A (CYP3A) isozymes. Typical rodent models do not predict drug-drug interactions mediated by human PXR because of species differences in response to PXR ligands. In the current study, a PXR-humanized mouse model was generated by bacterial artificial chromosome (BAC) transgenesis in Pxr-null mice using a BAC clone containing the complete human PXR gene and 5'- and 3'-flanking sequences. In this PXR-humanized mouse model, PXR is selectively expressed in the liver and intestine, the same tissue expression pattern as CYP3A. Treatment of PXR-humanized mice with the PXR ligands mimicked the human response, since both hepatic and intestinal CYP3As were strongly induced by rifampicin, a human-specific PXR ligand, but not by pregnenolone 16alpha-carbonitrile, a rodent-specific PXR ligand. In rifampicin-pretreated PXR-humanized mice, an approximately 60% decrease was observed for both the maximal midazolam serum concentration (C(max)) and the area under the concentration-time curve, as a result of a 3-fold increase in midazolam 1'-hydroxylation. These results illustrate the potential utility of the PXR-humanized mice in the investigation of drug-drug interactions mediated by CYP3A and suggest that the PXR-humanized mouse model would be an appropriate in vivo tool for evaluation of the overall pharmacokinetic consequences of human PXR activation by drugs.
authors.affiliation: Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: Xiaochao
authors.initials: X
authors.lastname: Ma
authors.forename: Yatrik
authors.initials: Y
authors.lastname: Shah
authors.forename: Connie
authors.initials: C
authors.lastname: Cheung
authors.forename: Grace L
authors.initials: GL
authors.lastname: Guo
authors.forename: Lionel
authors.initials: L
authors.lastname: Feigenbaum
authors.forename: Kristopher W
authors.initials: KW
authors.lastname: Krausz
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Idle
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Gonzalez
mesh_terms: D000818:Animals; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000502:physiology*; D004347:Drug Interactions; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008874:Midazolam / Q000493:pharmacokinetics; D023421:Models, Animal; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid / Q000235:genetics*; D008565:Membrane Proteins
chemical_list: D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System; D008874:Midazolam; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid; C496508:Cyp3a11 protein, mouse; D008565:Membrane Proteins