Overexpression of miR-34a attenuated the metastasis and angiogenesis of bladder cancer in vivo. A, hematoxylin/eosin (HE) and immunohistochemical staining revealed that stable transfection of miR-34a precursor resulted in decreased expression of VEGF, CD44 and CD31 within tumors. The mean vessel density within tumors decreased after stable overexpression of miR-34a. B, T24 cells were injected into the tail vein of nude mice (5 × 106cells per mouse). Tumor cells stably infected with miR-34a lentivirus established significantly fewer metastatic colonies. C, Representative photographs of immunofluorescence were taken at × 400 magnification.