Assessing the carcinogenic potential of drug candidates is a costly procedure which requires the life-long treatment of rodents at different dose levels. A promising approach, which may to a certain degree reduce the need for animal studies in the future is toxicogenomics. The idea is to employ microarray platforms for the genome-wide expression profiling of compounds, which may facilitate the discovery of biomarker genes and provide insights in molecular mechanisms. We profiled global mRNA expression in the liver of male and female CD-1 mice treated with genotoxic, nongenotoxic, and non-hepatocarcinogenic compounds up to two weeks.
Diverse compounds were administrated to male and female mice CD-1 mice by oral gavage up to 14 days. In order to chose appropriate dose levels for the carcinogenic substances, the dose reported to be carcinogenic in the 2-year mouse bioassay as stated in the CPDB database (http://potency.berkeley.edu/) was used. To ensure clearly visible changes in gene expression in response to treatment with non-hepatocarcinogens, a high dose was used for these compounds. After 3 and 14 days of treatment, respectively, the animals were anesthetized using isoflurane, exsanguinated from the heart and then subjected to necropsy. The median lobe and left lateral liver lobe were cut in cubes with 4-5 mm side length, placed in Wheaton Cryovials, snap frozen in liquid nitrogen and kept at -80°C until extraction.