The Maturation of Tumor Suppressor miR-497 in Hepatocellular Carcinoma is Inhibited by Oncogenic circRNA SCARB1

INTRODUCTION: Circular RNA (CircRNA) SCARB1 plays an oncogenic role in renal cell carcinoma, while its role in other cancers is unclear. The aim of this study was to explore the role of circRNA SCARB1 in hepatocellular carcinoma (HCC). METHODS: The expression of circRNA SCARB1, mature miR-497 and miR-497 precursor in HCC and paired non-tumor tissues from 64 HCC patients were analyzed by RT-qPCR. CircRNA SCARB1 was overexpressed in HCC cells, followed by the measurement of the expression levels of both mature miR-497 and miR-497 precursor to evaluate the effects of overexpression of circRNA SCARB1 on the maturation of miR-497. The effects of circRNA SCARB1 and miR-497 on the proliferation and migration of HCC cells were assessed by CCK-8 assay and Transwell assay, respectively. RESULTS: We found that circRNA SCARB1 was upregulated in HCC. In addition, mature miR-497 and miR-497 were downregulated in HCC. Correlation analysis showed that circRNA SCARB1 was inversely correlated with mature miR-497 but not miR-497 precursor. Consistently, in HCC cells, downregulated mature miR-497, but not miR-497 precursor, was observed in HCC cells transfected with circRNA SCARB1 expression vector. Analysis of cellular behaviors showed that overexpression of circRNA SCARB1 increased the proliferation and migration of HCC cells, while overexpression of miR-497 decreased cell proliferation and migration. Moreover, overexpression of miR-497 reduced the effects of overexpression of circRNA SCARB1. DISCUSSION: Therefore, circRNA SCARB1 is upregulated in HCC and promotes HCC cell proliferation and migration by suppressing the maturation of miR-497.