miR-639 promotes the proliferation and invasion of breast cancer cell in vitro.

Breast cancer is characterised by an elevated capacity for tumour invasion and lymph node metastasis, but the cause remains to be determined. Recent studies suggest that microRNAs can regulate the evolution of malignant behaviours by regulating multiple target genes. In this study, we have first confirmed that miR-639 is up-regulated in metastatic breast cancer tissues and cell line with highly invasive capacity. Furthermore, we provided evidence to demonstrate that up-regulation of miR-639 contributes breast cancer invasion and metastasis. These data reveal a key role of miR-639 in breast cancer metastasis and support biological and clinical links between miR-639 and breast cancer.