Circ_0006404 Accelerates Prostate Cancer Progression Through Regulating miR-1299/CFL2 Signaling

BACKGROUND: Circular RNAs (circRNAs) have been proven to function as pivotal regulators in cancer occurrence and progression. However, the function of circ_0006404 (circRNA Forkhead box O3 (circFOXO3)in prostate cancer (PCa) is poorly understood. METHODS: The enrichment of circ_0006404, FOXO3, microRNA-1299 (miR-1299) and cofilin 2 (CFL2) was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The viability, metastasis and proliferation were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, transwell and colony formation assays, respectively. Flow cytometry was used to assess cell cycle progression and apoptosis. Circ_0006404/miRNAs interactions were explored using Circular RNA Interactome database, while TargetScan software was used for seeking the targets of miR-1299. Dual-luciferase reporter assay, RNA-pull down and RNA immunoprecipitation (RIP) assays were conducted to verify the target interaction between miR-1299 and circ_0006404 or CFL2. CFL2 protein level was analyzed by Western blot assay. Animal experiments were performed to test the role of circ_0006404 in PCa tumor growth in vivo. RESULTS: Circ_0006404 level was notably elevated in PCa. Circ_0006404 contributed to the viability, metastasis and proliferation and impaired the apoptosis of PCa cells. Circ_0006404 directly targeted miR-1299, and miR-1299 silencing largely reversed circ_0006404 interference-induced influences in PCa cells. CFL2 directly bound to miR-1299, and miR-1299-induced effects in PCa cells were largely attenuated by CFL2 overexpression. CFL2 was regulated by circ_0006404/miR-1299 axis in PCa cells. Circ_0006404 promoted PCa progression via miR-1299/CFL2 axis in vivo. CONCLUSION: Circ_0006404 accelerated the survival, motility and proliferation while impeded the apoptosis of PCa cells via miR-1299/CFL2 axis. Circ_0006404 might be a stable potential bio-marker for PCa diagnosis and treatment.