Circular RNA circRIMS1 acts as a sponge of miR-433-3p to promote bladder cancer progression by regulating CCAR1 expression

Abstract Circular RNAs (circRNAs), a subclass of noncoding RNAs, are reportedly involved in the progression of various diseases. However, the exact role of circRIMS1, also termed hsa_circ_0132246, in human bladder cancer remains unknown. By performing RNA sequencing comparing bladder cell lines and normal uroepithelial cells, circRIMS1 was selected as a research object. We further verified by qRT-PCR that circRIMS1 is upregulated in both bladder cancer tissue and cell lines. Proliferation, colony formation, Transwell migration, invasion, apoptosis, western blotting and in vivo experiments were utilized to clarify the roles of circRIMS1, miR-433-3p and CCAR1. For mechanistic investigation, RNA pull-down, fluorescence in situ hybridization (FISH) and luciferase reporter assay confirmed the binding of circRIMS1 with miR-433-3p. Inhibition of circRIMS1 suppressed the proliferation, migration and invasion of bladder cancer cells both in vitro and in vivo. Moreover, the circRIMS1/miR-433-3p/CCAR1 regulatory axis was confirmed to be responsible for the biological functions of circRIMS1. Taken together, our research demonstrated that circRIMS1 promotes tumor growth, migration and invasion through the miR-433-3p/CCAR1 regulatory axis, representing a potential therapeutic target and biomarker in bladder cancer.