ErbB2 down-regulates microRNA-205 in breast cancer

► MiR-205 was markedly down-regulated in erbB2-transformed breast epithelial cells. ► Restoring miR-205 expression reduced colony formation of the erbB2-transformed cells. ► In these cells, cyclin E was shown to be negatively correlated with miR-205 levels. ► This work provides a rationale for miR-205 as a novel therapeutic target for erbB2-positive breast cancers.