circNFATC3 sponges miR-548I acts as a ceRNA to protect NFATC3 itself and suppressed hepatocellular carcinoma progression.

Circular RNAs (circRNA) have been reported as regulators involved in hepatocellular carcinoma (HCC), but their mechanism of activity remains unknown. This study performed quantitative reverse-transcription polymerase chain reaction to determine if circNFATC3 was downregulated in 46 paired HCC tissues and cell lines. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, apoptotic, and transwell assay proved that circNFATC3 can inhibit hepatoma cell proliferation, apoptosis, and migration/invasion in vitro. Mouse xenograft assay demonstrated that circNFATC3 suppressed tumor size and weight and reduced lung metastasis in vivo, and vice versa. The RNA-seq results showed that NFATC3 itself was the most significantly differentially expressed gene when circNFATC3 was manipulated, and bioinformatics and luciferase reporter assays verified circNFATC3 regulated the expression of NFATC3 by interacting with the hsa-miR-548I. Additionally, it was also indicated that the level of NFATC3 was downregulated in HCC patients also and was significantly correlated with the staging and prognosis of HCC. Moreover, both circNFATC3 and NFATC3 were shown to inhibit the phosphorylation of JNK, c-Jun, AKT, and mTOR signaling pathways. Overall, the circNFATC3 can sponge miR-548I to protect NFATC3 itself, then it regulates hepatoma cell function via the JNK, c-Jun, AKT, and mTOR signaling pathways, and the circNFATC3 can be a tumor-repressor on HCC.