circEPS15 overexpression in hepatocellular carcinoma modulates tumor invasion and migration

This study evaluates the effect circular RNA (circRNA) has on the development of hepatocellular carcinoma (HCC), which has been an area of limited information in the field. Through microarray analysis, we identified and then characterized the circRNA, circEPS15, which is downregulated in HCC tissue compared to noncancerous tissues. Our analysis shows that overexpressing circEPS15 could reduce tumor cell migration through the inhibition of cell cycle signaling pathways, suggesting this circRNA could be a target for novel HCC therapies. Moreover, we show that circEPS15 encodes a functional protein that could contribute to its antitumor effects. We believe that our study makes a significant contribution to the literature because it both clarifies the molecular mechanisms of circRNA in cell growth and development, as well as provides novel marker or target candidates for improving HCC diagnosis and treatment. Total RNAs were digested with RNase R (20 U/μL, Epicentre, Madison, WI, USA) to remove linear RNAs and enrich circular RNAs. The enriched circular RNAs were amplified and transcribed into fluorescent cRNA utilizing a random priming method (Super RNA Labelling Kit; Arraystar, Rockville, MD, USA). The labeled cRNAs were hybridized onto the Human circRNA Array (8 × 15K, Arraystar). The slides were incubated for 17 h at 65°C in a hybridization oven (Agilent Technologies, Santa Clara, CA, USA). CircRNAs, with statistically significant fold-change differential expression between HCC and paired normal tissues (FC ≥ 2 and p ≤ 0.05) were identified by Volcano plot filtering. Hierarchical clustering was performed to determine the distinguishable expression pattern of circRNAs among samples.