Differential Expression of microRNAs in Equine Sarcoids: Preliminary Results from an In Vitro Model

Reasons for performing the study Equine sarcoids are locally aggressive fibroblastic cutaneous tumours, representing the third most common health problem in working horses. In developed countries they also have welfare and economic impact (e.g. prepurchase examination). No current treatment offers 100% success rate. It is now well established that Bovine Papillomavirus (BPV) types 1 and 2 play an important role in the pathogenesis of sarcoid tumours. In a number of human cancers, aberrant expression of microRNAs has been linked to the cancerous phenotype. microRNAs are small noncoding RNAs that regulate essential biological and cellular processes. Currently there is much interest in their role as biomarkers and potential therapeutic agents for many diseases. Objectives In an attempt to improve our understanding of the pathobiology of sarcoids, we aim to identify specific microRNAs associated with equine sarcoids. Study design Differential expression of microRNAs was assessed in control equine fibroblasts (EqPalfs) and EqPalfs transformed with the BPV-1 genome (S6-2s). Methods Using a commercially available human microarray, 453 microRNAs were interrogated in RNA samples from both cell lines. Each cell line was analysed in triplicate. Results 219 individual microRNAs were differentially expressed in control (EqPalFs) versus BPV-transformed cells (S6-2s) (P<0.05). of these, 148 microRNAs (68%) were underexpressed in S6-2 cells relative to EqPalfs. Conclusions We have shown that BPV-1 transformed equine cell lines exhibit a different microRNA profile to control equine fibroblasts and the aberrant expression of microRNAs in S6-2 cells can be attributed to the presence of BPV-1 genomes. Our future work will focus on studying the expression profiles of a subset of microRNAs in a larger panel of cell lines and sarcoid tumours to help elucidate the significance of the deregulated expression. Ethical animal research: Local ethical approval was granted to conduct this study. Sources of funding: This work is funded by the Horserace Betting Levy Board with contribution from the Vet Trust Fund (James Herriot Scholarship). Competing interests: None.