The aberrant expression of microRNAs (miRNAs) is involved in the initiation and progression of human cancers. In our study, we found that miR-539 was down-regulated in breast cancer tissues and cell lines. Decreased expression of miR-539 was significantly associated with lymph node metastasis in patients with breast cancer. Overexpression of miR-539 inhibited the proliferation and promoted apoptosis of breast cancer cells. Moreover, highly expressed miR-539 significantly suppressed the epithelial-mesenchymal transition (EMT) and sensitized cells to cisplatin treatment. Mechanistically, miR-539 was found to target the specificity protein 1 (SP1) and down-regulated the expression of SP1 in breast cancer cells. Knockdown of miR-539 consistently increased the expression of SP1. The expression of miR-539 in breast cancer tissues was negatively correlated with the expression of SP1. Restoration of SP1 significantly attenuated the inhibitory effect of miR-539 on the proliferation of breast cancer cells. Taken together, our results indicate that miR-539 has a tumor suppressive role in breast cancer via targeting SP1, suggesting miR-539 as a promising target for the diagnosis of breast cancer.
Keywords: SP1; breast cancer; cancer du sein; miR-539.