This SuperSeries is composed of the SubSeries listed below.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Sex, Age, Specimen part, Treatment, Subject, Time
View SamplesThe carcinogenic potential of chemicals is currently evaluated with rodent life-time bioassays, which are time consuming, and expensive with respect to cost, number of animals and amount of compound required. For insight into early mechanisms of non-genotoxoc carcinogenesis and for identification of potential early biomarkers of non-genotoxic carcinogenesis, groups of rats were treated with a range of known non-genotoxic carcinogens for a period of 14, 28, or 90 days, and liver tissue was harvested for expression profiling. Control groups were treated with appropriate vehicles.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Sex, Specimen part, Treatment, Subject
View SamplesConventional notion regards the action of non-genotoxic carcinogens (NGC) an autonomous process largely confined to parenchymal cells. Here we aim to elucidate the role of the hepatic mesenchyme for the action of two prototypical NGC, phenobarbital (PB), an anti-epileptic drug, and cyproterone acetate (CPA) a gestagen used in contraceptive pills.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Sex, Specimen part, Treatment
View SamplesHere we investigate the difference in global gene expression in different tumor types found in the liver of rats after NNM-initiation/PB-promotion of tumor growth. We aim to identify tumor characteristic expression in nodules, focii, adenomas and carcinomas.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Sex, Specimen part, Treatment
View SamplesEvidence 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.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Sex, Specimen part, Treatment, Subject
View SamplesSignaling through the Wnt/b-catenin pathway is a crucial determinant of hepatic zonal gene expression, liver development, regeneration, and tumorigenesis. The gene encoding b-catenin is called Ctnnb1. We have previously shown, that liver tumour promotion mediated by the model tumour promoter phenobarbital (PB) is completely lost in mice, where Ctnnb1 has been conditionally knocked out in hepatocytes (CTNNB1KO mice; Rignall et al., Carcinogenesis 32, 52-57, 2010). In the present study, the effect of a 12 weeks PB exposure on the liver miRNA expression pattern was investigated, in order to potentially get information on the nature of the loss of promotional activity in the CTNNB1KO mice.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Sex, Specimen part
View SamplesConventional notion regards the action of non-genotoxic carcinogens (NGC) an autonomous process largely confined to parenchymal cells. Here we aim to elucidate the role of the hepatic mesenchyme for the action of a prototypical NGC, phenobarbital (PB), an anti-epileptic drug.
Phenobarbital mediates an epigenetic switch at the constitutive androstane receptor (CAR) target gene Cyp2b10 in the liver of B6C3F1 mice.
Specimen part, Treatment
View SamplesThe molecular events during nongenotoxic carcinogenesis and their temporal order are poorly understood but thought to include long-lasting perturbations of gene expression. Here, we have investigated the temporal sequence of molecular and pathological perturbations at early stages of phenobarbital (PB) mediated liver tumor promotion in vivo. Molecular profiling (mRNA, microRNA [miRNA], DNA methylation, and proteins) of mouse liver during 13 weeks of PB treatment revealed progressive increases in hepatic expression of long noncoding RNAs and miRNAs originating from the Dlk1-Dio3 imprinted gene cluster, a locus that has recently been associated with stem cell pluripotency in mice and various neoplasms in humans. PB induction of the Dlk1-Dio3 cluster noncoding RNA (ncRNA) Meg3 was localized to glutamine synthetase-positive hypertrophic perivenous hepatocytes, sug- gesting a role for -catenin signaling in the dysregulation of Dlk1-Dio3 ncRNAs. The carcinogenic relevance of Dlk1-Dio3 locus ncRNA induction was further supported by in vivo genetic dependence on constitutive androstane receptor and -catenin pathways. Our data identify Dlk1-Dio3 ncRNAs as novel candidate early biomarkers for mouse liver tumor promotion and provide new opportunities for assessing the carcinogenic potential of novel compounds.
Identification of Dlk1-Dio3 imprinted gene cluster noncoding RNAs as novel candidate biomarkers for liver tumor promotion.
Specimen part
View SamplesThe goal of this study was to generate a Drosophila model of intellectual disability caused by mutations in kdm5. RNA-seq was used to define the transcriptional defects of a mutation in Drosophila that is analogous to a human intellectual disability-associated allele, kdm5[A512p]. These data revealed a total of 1609 dysregulated genes, 778 of which were upregulated and 831 were downregulated. To determine whether these transcriptional defects were due to the loss of KDM5-induced histone demethylation, we also carried out RNA-seq from a enzymatic inactive strain, kdm5[Jmjc*]. These data revealed a striking similarity between the two datasets and suggest that the primary defect of KDM5[A512P] is loss of histone demethylase activity. Overall design: 3-5 day old adult heads from wildtype, kdm5[A512P] and kdm5[JmjC*] were used to generate RNA that was subsequently subjected to deep sequencing.
A Drosophila Model of Intellectual Disability Caused by Mutations in the Histone Demethylase KDM5.
Specimen part, Subject
View Samples