MicroRNAs and Their Predicted TargetMessenger RNAs are Deregulated by Exposure to a Carcinogenic Dose of Comfrey in Rat Liver

MicroRNAs (miRNAs) are small non-coding RNAs that function as regulators of gene expression to control cell growth and differentiation. MiRNA levels are substantially altered in various types of tumors and have been used as biomarkers in defining malignant status. However, studies on responses of miRNA expression to carcinogen insults in their target tissues are rare. In this study, we analyzed miRNA expression in the livers of rats treated with carcinogenic dose of comfrey (Symphytum officinale), a rat botanical carcinogen. Groups of 6 Big Blue Fisher 344 rats were fed a normal diet or a diet containing 8% comfrey root for 12 weeks. The animals were sacrificed one day after the last treatment and the livers were isolated from the control and treated rats for miRNA expression analysis. The miRNA expressions were determined using miRNA microarrays for human, mouse and rat (LC Sciences). Data were normalized using cyclic method and statistically analyzed using Ttest.