circRASGRF2 functions as an oncogenic gene in hepatocellular carcinoma by acting as a miR-1224 sponge.

Circular RNAs (circRNAs) are a class of non-coding RNAs broadly expressed in cells of various species. However, the contributions and molecular mechanisms of circRNAs to hepatocellular carcinoma (HCC) remain largely unknown. In the present study, we compared the expression of circRNAs between five paired HCC and adjacent noncancerous liver (ANL) tissues by using RNA-sequencing (RNA-seq). circRASGRF2 (a circRNA located on chromosome 5 and derived from RASGRF2, hsa_circ_0073181) was identified and validated by quantitative reverse transcriptase PCR. The role of circRASGRF2 in HCC progression was assessed both in vitro and in vivo. Mechanistically, RNA immunoprecipitation and luciferase reporter assays were performed to confirm the interaction between circRASGRF2 and miR-1224 in HCC. circRASGRF2 was found to be significantly upregulated in HCC tissues and HCC cell lines compared with paired ANL tissues and normal cells. Our in vivo and in vitro data indicated that knockdown of circRASGRF2 inhibits the proliferation and migration of HCC cells. Mechanistically, we found that circRASGRF2 could promote the expression of focal adhesion kinase (FAK) by sponging miR-1224. Our data showed that circRASGRF2 is a central component linking circRNAs to progression of HCC, making it a potential therapeutic target.