Circ_0001686 Promotes Prostate Cancer Progression by Up-Regulating SMAD3/TGFBR2 via miR-411-5p

Abstract Background: Prostate cancer (PCa) is one of the most common malignancies in men. Circular RNAs (circRNAs) are known to be the important regulators in cancer progression. However, the role of circRNAs in PCa is yet to be investigated. Therefore, this study focuses on investigating the effect and the underlying molecular mechanisms of hsa_circ_0001686 (circ_0001686) in PCa. Methods: Sample tissues were collected from the PCa patients to carry out the microarray expression profile of the human circRNAs. In addition, the expression levels of circ_0001686, has_miR-411-5p (miR-411-5p), SMAD3, and TGFBR2 were also detected by qRT-RCR. Next, transfection experiments were employed to measure the effect of circ_0001686 on cell proliferation, migration, and invasion in the PCa cell lines (CWR22RV1and LNCaP). These effects were analyzed using MTT, colony formation, transwell, and scratch wound assays, respectively. The si-circ_0001686 was used as a negative control. Starbase and TargetScan databases were used to predict the putative binding sites among circ_0001686, miR-411-5p, and SMAD3/TGFBR2. The dual-luciferase reporter assays were performed to verify these interactions. Furthermore, the levels of SMAD3 and TGFBR2 in CWR22RV1 and LNCaP cells were measured by western blot. Finally, in vivo experiments in the nude mouse model were carried out to strengthen the in vitro findings. Results: The expression of circ_0001686 was markedly up-regulated while the expression of miR-411-5p was down-regulated in PCa cells. Moreover, circ_0001686 promoted cell proliferation, migration, and invasion. Molecular mechanism exploration revealed that circ_0001686 acts as a sponge of miR-411-5p which affects the downstream target gene SMAD3, and TGFBR2. Both the in vitro and in vivo studies verified that miR-411-5p inhibits cancer growth and metastasis in PCa. Conclusions: The circ_0001686 sequesters miR-411-5p to increase the expression of SMAD3/TGFBR2 which consequently promotes the proliferation, invasion, and migration in PCa cells.