Lack of hepatic response of microRNA in mice following DB[a,h]A exposure (Agilent expression). Mus musculus

Dibenzo[a,h]anthracene DB[a,h]A is a polycyclic aromatic hydrocarbon potent carcinogen. Few studies have investigated the role of DB[a,h]A on mRNA and miRNA expression. In this study a 10-week old male MutaTM Mouse were exposed to 6.25, 12.5, and 25 mg/kg/day DB[a,h]A by oral gavage for 28 consecutive days. DNA adducts were detected in the livers at each DB[a,h]A dose tested, and a dose-dependent increase in lacZ mutants was observed in the same samples. MAANOVA analysis revealed minor changes in the mRNA expression for the two lowest doses. Differential expression of 19 up-regulated and 22 down-regulated transcripts with fold-change > 1.5 (FDR-adjusted P 1.5). Major effect on mRNA expression resulted from exposure to the highest dose (25 mg/kg/day) of DB[a,h]A with 135 up-regulated and 104 down-regulated genes with fold-change > 1.5 (FDR-adjusted P < 0.05). The significantly regulated genes are involved in circadian rhythm, drug metabolism, glucose metabolism, cholestrol and lipid metabolism, immune response, cell cycle, and apoptosis. We also investigated miRNA response to the three doses of DB[a,h]A. MiRNA expression was relatively unaffected. Only miR-34a showed significant (FDR-adjusted P < 0.05) up-regulation with a fold change above 1.3-fold. Overall design: Individual total RNA (200 ng) from 4-5 mice per treatment group (control, 6.25 mg/kg, 12.5mg/kg, and 25mg/kg) and universal reference total RNA (Stratagene, Mississauga, ON, Canada) was used to synthesize double stranded cDNA. Agilent mouse 8 x 60 K oligonucleotide microarrays were used to assess global gene expression in response to 6.25, 12.50, and 25 mg/kg DB[a,h]A treatment