Cross-platform toxicogenomics for the prediction of nongenotoxic hepatocarcinogenesis in rat (mRNA)

In this study we performed microarray-based molecular profiling of liver samples from Wistar rats exposed to genotoxic carcinogens (GC), nongenotoxic carcinogens (NGC) or non-hepatocarcinogens (NC) for up to 14 days. In contrast to previous toxicogenomics studies aimed at the inference of molecular signatures for assessing the potential and mode of compound carcinogenicity, we considered multi-level omics data. Besides evaluating the predictive power of signatures observed on individual biological levels, such as mRNA, miRNA and protein expression, we also introduced novel feature representations which capture putative molecular interactions or pathway alterations by integrating expression profiles across platforms interrogating different biological levels. Male Wistar rats were treated by oral gavage with the eight nongenotoxic hepatocarcinogens Phenobarbital sodium (PB), Piperonylbutoxide (PBO), Dehydroepiandrosterone (DHEA), Acetamide (AA), Methapyrilene HCl (MPy), Methylcarbamate (Mcarb), Diethylstilbestrol (DES) and Ethionine (ETH), the two genotoxic carcinogens C.I Direct Black (CIDB) and dimethylnitrosamine (DMN), the two non-hepatocarcinogens Cefuroxime (CFX) and Nifedipine (Nif), and the three compounds with undefined carcinogenic class Cyproterone acetate (CPA), Thioacetamid (TAA) and Wy-14643 (Wy). Depending on the administered compound, livers were taken after 3, 7, or 14 days for histopathological evaluation. From the five animals per treatment group three animals were selected based on the histopathological findings and subjected to molecular profiling using Affymetrix RG-230A arrays (mRNA expression), Agilent G4473A arrays (miRNA expression) and Zeptosens ZeptoMARK reverse arrays (protein expression).