Downregulation of MiR-196b-5p impedes cell proliferation and metastasis in breast cancer through regulating COL1A1.

Breast cancer is considered to be the most frequently diagnosed malignancy in women worldwide. MicroRNAs (miRNAs) play key roles in the regulation of tumor properties based on their capacity to regulate the expression of tumor-related genes. However, the involvement of miR-196b-5p in breast cancer development is largely unknown. Here, we showed that the expression levels of miR-196b-5p were significantly down-regulated in breast cancer samples and cell lines compared to the matched normal tissues and breast epithelial cell line, respectively. Notably, the expression of miR-196b-5p was negatively associated with lymph node metastasis and the progression of clinical stage in patients with breast cancer. MiR-196b-5p over-expression significantly inhibited the proliferation and migration of MDA-MB-231 and MDA-MB-468 cells in breast cancer. Furthermore, combining bioinformatics prediction and biochemical analyses, we showed that COL1A1 (collagen type I alpha 1 chain) was a direct downstream target gene of miR-196b-5p. Furthermore, overexpression of COL1A1 partly abrogated miR-196b-5p-mediated inhibition of proliferation and migration in MDA-MB-231 and MDA-MB-468 cells. Our data collectively indicate that miR-196b-5p inhibits cell growth and metastasis in breast cancer through down-regulating COL1A1, supporting the targeting of the new miR-196b-5p/COL1A1 axis as a promising effective therapeutic approach for breast cancer.