Purpose: MicroRNA (miR)-194-5p is downregulated in bladder cancer (BC), but its role in BC has not been determined mechanistically.
Methods: The expression levels of miR-194-5p and E2F transcription factor 3 (E2F3) were determined by means of quantitative reverse transcription and polymerase chain reaction in BC specimens. In addition, T24 BC cells were transfected with a miR-194-5p mimic, a miR-194-5p inhibitor, or E2F3 small interfering (si)RNA, and the level of E2F3 protein expressed by these cells was assessed by western blotting. A dual luciferase reporter assay was applied to verify the binding site between miR-194-5p and the 3' untranslated region of E2F3. Transwell assays were performed to examine cell migration and invasion.
Results: Dysregulation of miR-194-5p in BC was closely associated with node metastasis and differentiation. In BC specimens and cell lines, miR-194-5p mRNA was downregulated, while E2F3 mRNA was upregulated. Overexpression of miR-194-5p suppressed the expression of E2F3 mRNA and protein. By regulating E2F3, miR-194-5p inhibited cell migration and invasion in BC. Treatment of BC cells with E2F3 siRNA had the same effect as did overexpression of miR-194-5p.
Conclusions: MiR-194-5p directly targets E2F3 and inhibits cell migration and invasion in BC.