MiR-34a functioned as a tumor suppressor in MIBC cells. A) The effect of ectopic miR-34a expression on MIBC cell proliferation was investigated by CCK-8. The miR-34a activity was mediated by transfection with miR-34a mimics or inhibitor respectively. Data are plotted as the mean ± SEM of 3 independent experiments relative to mock treatments. The effect of ectopic miR-34a expression on MIBC cell tumorgenesis was investigated by B) colony-formation and C) sphere-formation assay. Quantitative analyses of D) colony and E) sphere numbers (mean + SEM; n = 3; *p < 0.05). F) Relative miR-34a expression in xenografts; G) Photographs of tumors excised 38 days after inoculation of stably transfected cells into nude mice; Mean xenograft tumor volume H) and weight I) in nude mice groups after indicated treatment (mean + SEM; n = 3; *p < 0.05).