MicroRNA-1298-5p inhibits cell proliferation and invasion of bladder cancer via downregulating connexin 43.

MicroRNA (miR)-1298 is widely down-regulated in various malignant tumors, which facilitates cell proliferation, invasion and migration. However, the specific biological function of miR-1298 in bladder cancer (BC) is still unknown. Connexin 43 (Cx43) is often up-regulated in different tumors. Identifying miRNAs that target Cx43 in the setting of BC will help to develop Cx43-based therapies for BC. In this study, the results demonstrated that the expression levels of miR-1298 and Cx43 were significantly down-regulated and up-regulated in BC clinical tissues, respectively. The overexpression of miR-1298 inhibited cell proliferation, migration, and invasion in two BC cell lines via MTT assay, cell cycle assay, colony formation assay, transwell assay, gelatin zymography, and western blot, respectively. In addition, it was found that miR-1298 decreased Cx43 expression by directly targeting the 3'-UTR. Following, we observed that the promotion effect of Cx43 on BC cell proliferation, migration, and invasion could be partially attenuated by miR-1298 overexpression. Moreover, the protein expression of p-ERK was ameliorated after transfected with overexpressed-miR-1298. The knockdown of Cx43 reversed the promotion effect of cell migration and invasion due to the decreased miR-1298 expression. All data suggest miR-1298 might be a potential therapeutic agent and diagnostic marker of BC by inhibiting Cx43.