Comparison of the induction profile for drug disposition proteins by typical nuclear receptor activators in human hepatic and intestinal cells

• Published in: British journal of pharmacology Vol. 153; no. 4; pp. 805 - 819
• Main Authors: Martin, P, Riley, R, Back, D J, Owen, A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2008; Nature Publishing; Nature Publishing Group
• Subjects: Aryl Hydrocarbon Hydroxylases - biosynthesis; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1 - biosynthesis; ATP-Binding Cassette Transporters - biosynthesis; ATP-Binding Cassette Transporters - genetics; Biological and medical sciences; Caco-2 Cells; CAR; Cell Culture Techniques; Cells, Cultured; Chenodeoxycholic Acid - pharmacology; Cytochrome P-450 CYP2B6; Cytochrome P-450 CYP3A - biosynthesis; Cytochrome P-450 Enzyme System - biosynthesis; Cytochrome P-450 Enzyme System - genetics; cytochrome P450; Dexamethasone - pharmacology; DNA-Binding Proteins - agonists; Dose-Response Relationship, Drug; Enzyme Induction; Epithelial Cells - drug effects; Epithelial Cells - metabolism; FXR; Hepatocytes - drug effects; Hepatocytes - metabolism; Humans; Intestinal Mucosa - drug effects; Intestinal Mucosa - metabolism; MDR1; Medical sciences; Membrane Transport Proteins - biosynthesis; Multidrug Resistance-Associated Proteins - biosynthesis; Oxidoreductases, N-Demethylating - biosynthesis; Pharmacology. Drug treatments; Phenobarbital - pharmacology; Pregnane X Receptor; Pregnenolone Carbonitrile - pharmacology; PXR; P‐glycoprotein; Receptors, Cytoplasmic and Nuclear - agonists; Receptors, Cytoplasmic and Nuclear - biosynthesis; Receptors, Steroid - agonists; Research Design; Research Papers; Rifampin - pharmacology; RNA, Messenger - biosynthesis; Transcription Factors - agonists; Up-Regulation; Human; Drug; FXR; Nuclear receptor; Digestive system; Enzyme; Induction; Cytochrome P450; Liver; Pregnane X receptor; P Glycoprotein; Gut; PXR; In vitro; Protein; P-glycoprotein; MDR1; CAR; MDR-1 gene; Pharmacokinetics; Comparative study
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1038/sj.bjp.0707601

Background and purpose: Certain nuclear receptors (NRs) such as the constitutive androstane receptor (CAR), pregnane X receptor (PXR) and farnesoid X receptor (FXR) mediate induction of some cytochrome P450 enzymes and ABC transporters but conflicting reports exist. The purpose of this study was to assess the reasons for these discrepancies and use a standardized approach to compare activators of NRs. Experimental approach: Dexamethasone, pregnenolone 16α‐carbonitrile, rifampicin, phenobarbital and chenodeoxycholic acid were incubated with HepG2, Caco‐2 and cryopreserved human hepatocytes prior to analysis of mRNA and protein for CYP2B6, CYP3A4, CYP3A5, ABCB1, ABCC1, ABCC2, PXR, CAR and FXR. Key results: Dexamethasone significantly up‐regulated PXR, CYP3A4 and ABCB1 expression in HepG2 and Caco‐2 cells. As a result, including dexamethasone as a media supplement masked the induction of these genes by pregnenolone 16α‐carbonitrile, which may explain discrepancies between previous reports. In the absence of dexamethasone, significant activator‐dependent induction was observed in all cell types. Significant correlations were observed between the fold increase in mRNA and in protein, which were, for most instances, logarithmic. Changes in mRNA expression were greater in cell lines than primary cells but for most transcripts correlations were observed between fold increases in HepG2 and hepatocytes. Conclusions and implications: Clearly, no in vitro system can imitate the physiology of a hepatocyte or intestinal cell within an intact organ in vivo, but these data explain some of the discrepancies reported between laboratories and have important implications for study design. British Journal of Pharmacology (2008) 153, 805–819; doi:10.1038/sj.bjp.0707601; published online 26 November 2007