MicroRNA-497 inhibits the proliferation, migration and invasion of human bladder transitional cell carcinoma cells by targeting E2F3

Accumulating evidence indicates that microRNAs (miRNAs) play critical roles in regulating cellular processes, such as cell growth and apoptosis, as well as cancer progression and metastasis. Low expression of miR-497 has been observed in breast, colorectal and cervical cancers. Human bladder transitional cell carcinoma (BTCC) progression typically follows a complex cascade from primary malignancy to distant metastasis, but whether the aberrant expression of miR-497 in BTCC is associated with malignancy, metastasis or prognosis remains unknown. In the present study, we found that miR-497 was markedly downregulated in BTCC tissue samples when compared with that noted in adjacent normal tissues, and low expression of miR-497 was correlated with poor prognosis in BTCC patients. We also found that overexpression of miR-497 inhibited the proliferation, migration and invasion of bladder cancer cells by downregulating E2F3 (an miR-497 target gene) mRNA and protein and that siRNA against E2F3 inhibited cell proliferation, migration and invasion, which was similar to the effect of miR-497 overexpression in the BTCC cells. Our experimental data indicated that miR-497 mediates the in vitro proliferation, migration and invasion of BTCC cells. Together, these results suggest that miR-497 may represent a novel prognostic indicator, a biomarker for the early detection of metastasis and a target for gene therapy of BTCC.