Objective: Circular RNA is a type of endogenous RNA molecule with a stable closed-loop structure which is ubiquitous in mammals. Circular RNA HIPK3 (circHIPK3) is highly expressed in hepatocellular carcinoma and promotes the growth of hepatoma cells. However, its role in prostate cancer (PCa) has not been reported. This study aims to explore whether circHIPK3 could affect the proliferative and invasive potentials of PCa cells by regulating miRNA-338-3p. Methods: Expression levels of circHIPK3 and miRNA-338-3p in PCa tissues and cells were determined by RT-qPCR. The regulatory effects of circHIPK3 and miRNA-338-3p on proliferative and invasive potentials of PCa cells were evaluated by CCK-8 and transwell assay, respectively. We verified the binding between miRNA-338-3p and ADAM17, as well as miRNA-338-3p and circHIPK3 through dual-luciferase reporter gene assay. Rescue experiments were conducted to clarify whether circHIPK3 affected the proliferative and invasive potentials of PCa cells by regulating miRNA-338-3p. Results: Expression level of circHIPK3 in PCa tissues was remarkably higher than that of paracancerous tissues. Knockdown of circHIPK3 inhibited the proliferative and invasive rates of PC-3 and DU145 cells. Dual-luciferase reporter gene assay indicated that circHIPK3 could bind to miRNA-338-3p. Moreover, miRNA-338-3p expression was downregulated in PCa tissues. miRNA-338-3p expression was negatively correlated with lymph node metastasis and distant metastasis. miRNA-338-3p overexpression markedly reduced proliferative and invasive abilities of PC-3 and DU145 cells. Furthermore, ADAM17 was confirmed to be the target gene of miRNA-338-3p. Overexpression of ADAM17 enhanced proliferative and invasive abilities of PC-3 and DU145 cells. Finally, rescue experiments indicated that miRNA-338-3p knockdown in PC-3 and DU145 cells partially reversed the regulatory effects of circHIPK3 on proliferative and invasive potentials. Conclusion: Overexpression of circHIPK3 promotes the proliferative and invasive potentials of PCa cells through sponging miRNA-338-3p to regulate ADAM17 expression, thus accelerating the malignant progression of PCa.
Keywords: ADAM17; CircHIPK3; miRNA-338-3p; prostate cancer.