Circulating RNA ZFR promotes hepatocellular carcinoma cell proliferation and epithelial-mesenchymal transition process through miR-624-3p/WEE1 axis.

ABSTRACT

BACKGROUND: Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is the fourth leading cause of cancer-related deaths worldwide. Previous evidence shows that the expression of circulating RNA ZFR (circZFR) is upregulated in HCC tissues. However, the molecular mechanism of circZFR in HCC is unclear. METHODS: Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was employed to detect the expression of circZFR, microRNA-624-3p (miR-624-3p) and WEE1 in HCC tissues and cells. RNase R assay and actinomycin D treatment assay were used to analyze the characteristics of circZFR. For functional analysis, the capacities of colony formation, cell proliferation, cell apoptosis, migration and invasion were assessed by colony formation assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry assay and transwell assay. Western blot was used to examine the protein levels of WEE1 and epithelial-mesenchymal transition (EMT)-related proteins. The interactions between miR-624-3p and circZFR or WEE1 were validated by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Xenograft models were established to determine the role of circZFR in vivo. RESULTS: circZFR and WEE1 were upregulated, while miR-624-3p expression was reduced in HCC tissues and cells. circZFR could sponge miR-624-3p, and WEE1 was a downstream gene of miR-624-3p. Knockdown of circZFR significantly reduced the malignant behaviors of HCC and that co-transfection with miR-624-3p inhibitor restored this change. Overexpression of WEE1 abolished the inhibitory effect of miR-624-3p mimic on HCC cells. Mechanistically, circZFR acted as a competitive endogenous RNA (ceRNA) to regulate WEE1 expression by targeting miR-624-3p. Furthermore, in vivo studies have illustrated that circZFR knockdown inhibited tumor growth. CONCLUSIONS: circZFR knockdown reduced HCC cell proliferation, migration and invasion and promoted apoptosis by regulating the miR-624-3p/WEE1 axis, suggesting that the circZFR/miR-624-3p/WEE1 axis might be a potential target for HCC treatment.