Circular RNA circHIAT1 inhibits cell growth in hepatocellular carcinoma by regulating miR-3171/PTEN axis.

Circular RNAs (circRNAs), a novel subgroup of non-coding RNAs (ncRNAs), have been reported in human cancers due to their significant regulatory roles. CircRNA Hippocampus Abundant Transcript 1 (circHIAT1) has been studied in clear cell renal cell carcinoma. However, whether it can regulate the tumorigenesis of hepatocellular carcinoma (HCC) remains unclear. The expression level of circHIAT1 in HCC samples and cell lines was measured by qRT-PCR analysis. CircHIAT1 was expressed at a significantly low level in cancerous samples. Based on Kaplan-Meier survival analysis, we determined a positive correlation between the downregulation of circHIAT1 and the poor overall survival of HCC patients. Using subcellular fractionation and RNA FISH assay, we identified the predominant cytoplasmic localization of circHIAT1. Both in vitro and in vivo experiments demonstrated the suppressive effect of circHIAT1 on the HCC cell growth. Mechanistically, circHIAT1 acted as the miR-3171 sponge to upregulate PTEN in HCC. Finally, rescue assays demonstrated the role of circHIAT1/miR-3171/PTEN pathway in regulating HCC cell growth. Taken together, this study revealed the novel mechanism of circHIAT1 in HCC.