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.

中文翻译：

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MiR-539通过靶向SP1抑制乳腺癌细胞的恶性行为。

microRNA（miRNA）的异常表达与人类癌症的发生和发展有关。在我们的研究中，我们发现miR-539在乳腺癌组织和细胞系中被下调。miR-539的表达降低与乳腺癌患者的淋巴结转移密切相关。miR-539的过表达抑制乳腺癌细胞的增殖并促进其凋亡。此外，高表达的miR-539可显着抑制上皮-间充质转化（EMT），并使细胞对顺铂治疗敏感。从机理上讲，发现miR-539靶向特异性蛋白1（SP1），并下调了乳腺癌细胞中SP1的表达。沉默miR-539一直增加SP1的表达。乳腺癌组织中miR-539的表达与SP1的表达负相关。SP1的恢复显着减弱了miR-539对乳腺癌细胞增殖的抑制作用。两者合计，我们的结果表明，miR-539通过靶向SP1在乳腺癌中具有抑癌作用，表明miR-539是诊断乳腺癌的有希望的靶标。