MicroRNA-140 inhibits proliferation and promotes apoptosis and cell cycle arrest of prostate cancer via degrading SOX4.

Purpose: To explore the regulatory roles of microRNA-140 and SOX4 in prostate cancer (PCa) tissues and paracancerous tissues, and their underlying mechanism. Methods: MicroRNA-140 expressions in PCa tissues, paracancerous tissues and PCa cell lines were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Proliferation, apoptosis and cell cycle of PCa cells after altering expressions of microRNA-140 and SOX4 were detected by MTT assay and flow cytometry, respectively. The regulatory effect of microRNA-140 on SOX4 was detected by Western blot and qRT-PCR. The binding condition of microRNA-140 on SOX4 was verified by luciferase reporter gene assay. Results: MicroRNA-140 was downregulated in PCa tissues compared to paracancerous tissues. In particular, lower expression of microRNA-140 was found in PCa with Grade I+II compared to Grade III+IV. In vitro, microRNA-140 expression was negatively correlated with proliferative and invasive abilities, while positively correlated with apoptosis of PCa cells. MicroRNA-140 promoted cell cycle arrest in G0/G1 phase. SOX4 expression was inhibited by microRNA-140 overexpression in PCa cells. Conclusions: Downregulated microRNA 140 promotes proliferation and cell cycle arrest, but inhibits apoptosis of PCa cells. MicroRNA-140 inhibits PCa development via degrading SOX4l.