Circular RNA circRNA_103809 Accelerates Bladder Cancer Progression and Enhances Chemo-Resistance by Activation of miR-516a-5p/FBXL18 Axis

Background: Numerous researches have suggested that circular RNAs (circRNAs) play critical functions in bladder cancer (BC) progression. This study aims to investigate the potential roles of circRNA_103809 in regulating BC development. Methods: qRT-PCR was used to analyze gene expression. CCK8 and colony formation were used to analyze cell proliferation. Transwell was utilized to examine cell migration and invasion. Gemcitabine was used to analyze the effect of circRNA_103809 on the chemo-resistance of BC cells. Luciferase reporter assay was performed to detect the RNA interactions. Results: circRNA_103809 was highly expressed in BC tissues and cell lines. CircRNA_103809 high expression was associated with a poor progression in BC patients. CircRNA_103809 knockdown impaired the growth and metastasis of BC cells. Furthermore, circRNA_103809 silencing increased the sensitivity of BC cells to Gemcitabine treatment. CircRNA_103809 was the sponge for miR-516a-5p and promoted FBXL18 expression via restraining miR-516a-5p activity. Conclusion: circRNA_103809 promotes proliferation, migration, invasion and chemoresistance of BC cells through regulating miR-516a-5p/FBXL18 axis.