Suppression of cell growth and invasion by miR-205 in breast cancer.

MicroRNAs (miRNAs) are endogenously small non-coding RNAs which are capable of silencing gene expression at the posttranscriptional level. In this study, we report that miR-205 is significantly underexpressed in breast tumor compared to the matched normal breast tissue. Similarly, breast cancer cell lines including MCF-7 and MDA-MB-231 express a lower level miR-205 than the non-malignant MCF-10A cells. Of interest, ectopic expression of miR-205 significantly inhibits cell proliferation and anchorage independent growth as well as cell invasion. Furthermore, the animal model indicates that miR-205 suppresses lung metastasis. Finally, western blot combined with the luciferase reporter assays demonstrate that ErbB3 and vascular endothelial growth factor A (VEGF-A) are direct targets for miR-205 and this miR-205-mediated suppression is likely through the direct interaction with the putative miR-205 binding site in the 3’-untranslated region (3-UTR) of ErbB3 and VEGF-A. Together, these results suggest that miR-205 is a tumor suppressor in breast cancer.