title: Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
abstract: Evidence suggests that epigenetic perturbations are involved in the adverse effects associated with some drugs and toxicants, including certain classes of non-genotoxic carcinogens. Such epigenetic changes (altered DNA methylation and covalent histone modifications) may take place at the earliest stages of carcinogenesis and their identification holds great promise for biomedical research. Here, we evaluate the sensitivity and specificity of genome-wide epigenomic and transcriptomic profiling in phenobarbital (PB)-treated B6C3F1 mice, a well-characterized rodent model of non-genotoxic liver carcinogenesis. Methylated DNA Immunoprecipitation (MeDIP)-coupled microarray profiling of 17,967 promoter regions and 4,566 intergenic CpG islands was combined with genome-wide mRNA expression profiling to identify liver tissue-specific PB-mediated DNA methylation and transcriptional alterations. Only a limited number of significant anti-correlations were observed between PB-induced transcriptional and promoter-based DNA methylation perturbations. However, the constitutive androstane receptor (CAR) target gene Cyp2b10 was found to be concomitantly hypomethylated and transcriptionally activated in a liver tissue-specific manner following PB treatment. Furthermore, analysis of active and repressive histone modifications using chromatin immunoprecipitation revealed a strong PB-mediated epigenetic switch at the Cyp2b10 promoter. Our data reveal that PB-induced transcriptional perturbations are not generally associated with broad changes in the DNA methylation status at proximal promoters and suggest that the drug-inducible CAR pathway regulates an epigenetic switch from repressive to active chromatin at the target gene Cyp2b10. This study demonstrates the utility of integrated epigenomic and transcriptomic profiling for elucidating early mechanisms and biomarkers of non-genotoxic carcinogenesis.
authors: Investigative Toxicology, Preclinical Safety, Translational Sciences, Novartis Institutes for Biomedical Research, Basel, Switzerland.
authors: Harri
authors: H
authors: Lempiäinen
authors: Arne
authors: A
authors: Müller
authors: Sarah
authors: S
authors: Brasa
authors: Soon-Siong
authors: SS
authors: Teo
authors: Tim-Christoph
authors: TC
authors: Roloff
authors: Laurent
authors: L
authors: Morawiec
authors: Natasa
authors: N
authors: Zamurovic
authors: Axel
authors: A
authors: Vicart
authors: Enrico
authors: E
authors: Funhoff
authors: Philippe
authors: P
authors: Couttet
authors: Dirk
authors: D
authors: Schübeler
authors: Olivier
authors: O
authors: Grenet
authors: Jennifer
authors: J
authors: Marlowe
authors: Jonathan
authors: J
authors: Moggs
authors: Rémi
authors: R
authors: Terranova
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D047369:Chromatin Immunoprecipitation; D000090702:Constitutive Androstane Receptor; D018899:CpG Islands / Q000187:drug effects / Q000235:genetics; D000072467:Cytochrome P450 Family 2; D019175:DNA Methylation / Q000187:drug effects; D057890:Epigenomics / Q000379:methods*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D010634:Phenobarbital / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D013250:Steroid Hydroxylases / Q000235:genetics*
chemical_list: D000090702:Constitutive Androstane Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C101679:Cyp2b10 protein, mouse; D000072467:Cytochrome P450 Family 2; D010634:Phenobarbital