Changes in the miRNA profile under the influence of anabolic steroids in bovine liver.

miRNAs are regulatory RNA molecules. The analytical interest rose over the past 10 years especially in clinical diagnostics as miRNAs show specific expression patterns in several human diseases like diabetes or cancer. Therefore, it is expected that miRNA profiles might be used as biomarkers in early diagnosis. The idea of establishing biomarkers is also present in veterinary drug analysis, e.g. in the surveillance of illegal use of anabolics. Transcriptomics is a promising approach in the detection of anabolics misuse. However, miRNA expression patterns have shown their superiority over mRNA patterns in clinical diagnostics. Thus, the influence of anabolic steroids on miRNA expression in bovine liver should be investigated and an expression pattern should be validated, which might be used as a treatment biomarker. An animal experiment was conducted with 18 heifers equally allocated to a control and a treatment group, which was implanted with TBA plus E2. Liver samples were screened for miRNA expression using PCR arrays. Expression of 11 prominent miRNAs was validated via single assay qPCR. Herein, the following expression pattern could be found with an up-regulation of miR-29c and miR-103 and a down-regulation of miR-34a, miR-181c, miR-20a and miR-15a (p<0.05 each). Using principal components analysis (PCA), the control group could clearly be distinguished from the treatment group, when integrating gene expression results from both miRNA and mRNA. So, the combination of different transcribed targets (mRNA plus miRNA) might be a promising approach to find a valid expression pattern to be used for anabolic treatment screening.