Overexpression of circ_0021093 circular RNA forecasts an unfavorable prognosis and facilitates cell progression by targeting the miR-766-3p/MTA3 pathway in hepatocellular carcinoma

Increasing studies have demonstrated the important roles of circular RNAs (circRNAs) in human malignancies. Nevertheless, the molecular mechanisms and functions of circRNAs in hepatocellular carcinoma (HCC) are still not fully understood. In the present study, we evaluated circ_0021093 expression in 82 pairs of HCC tissues and 5 cell lines by qRT-PCR. The clinical implications of circ_0021093 were evaluated. In addition, the viability, apoptosis, migration and invasion capacities of different HCC cells were evaluated by gain-/loss-of-function experiments. Target prediction and dual-luciferase reporter experiments were performed to identify the molecular mechanisms of circ_0021093. Upregulation of circ_0021093 was found in HCC tumor samples and cells. Additionally, upregulated circ_0021093 was related to adverse clinical characteristics and an unfavorable prognosis. Furthermore, downregulated circ_0021093 attenuated cell growth, migration and invasion but increased cell apoptosis. By contrast, ectopically expressed circ_0021093 enhanced the abovementioned malignant biological behaviors. For mechanism exploration, circ_0021093 sponges of miR-766-3p were used in HCC cells. In addition, we found that metastasis-associated protein 3 (MTA3) was a direct target of miR-766-3p and that the oncogenic function of circ_0021093 was partly dependent on the miR-766-3p/MTA3 axis according to rescue assays. In conclusion, the circ_0021093/miR-766-3p/MTA3 regulatory axis may be an effective therapeutic target for HCC.