Circ_0058063 regulates CDK6 to promote bladder cancer progression by sponging miR‐145‐5p

Abstract Background The study was aimed to investigate the influence of circ_0058063 on tumorigenesis as well as the regulatory mechanism of circ_0058063/miR‐145‐5p/ CDK6 pathway in bladder cancer (BC). Methods Bioinformatics analysis was used to screen highly expressed circle RNA (circRNA) and search its downstream microRNA (miRNA) and protein. The expression level of circRNA, miRNA, and CDK6 in BC cell lines T24 and J82 were determined by quantitative real‐time polymerase chain reaction (qRT‐PCR) and western blot. Small interfering RNA was used to downregulate circ_0058063 expression. Cell proliferation, cell cycle, cell apoptosis, and cell migration of T24 cells and J82 cells were detected through MTT assay, flow cytometry, and wound‐healing assay, respectively. The relationships among miR‐145‐5p, circ_0058063, and CDK6 were confirmed through dual luciferase reporter assay. In vivo experiment was also performed to explore the impact of circ_0058063/miR‐145‐5p/ CDK6 pathway on tumorigenesis in BALB/c nude mice. Results Circ_0058063 was significantly overexpressed in BC tissues. The downregulation of circ_0058063 impaired BC cell proliferation and migration ability but improved cell apoptosis ability. Circ_0058063 repressed miR‐145‐5p, which inhibited the expression of CDK6 . Downregulation of circ_0058063 or miR‐145‐5p transfection contributed to more cells arresting in G0/G1 stage. MiR‐145‐5p suppressed cell growth and migration ability in BC, whereas CDK6 exerted the opposite influence on these cellular events. In vivo experiment also indicated that tumor development in BALB/c nude mice was repressed remarkably when circ_0058063 was downregulated. Conclusion Circ_0058063 acted as a sponge of miR‐145‐5p to promote BC progression by regulating CDK6 expression, which provided some potential targets for BC treatment.