MicroRNA-138 modulates metastasis and EMT in breast cancer cells by targeting vimentin

Increasing evidence indicates that dysregulation of microRNAs (miRNAs) plays critical roles in malignant transformation and tumor progression. In this study, in order to investigate the association of miR-138 with breast cancer we investigated the role of miR-138 in breast cancer metastasis. Levels of miR-138 were determined by qRT-PCR in 45 breast cancer samples. Cell migration and invasion assays were performed in a stably expressing miRNA-138 breast cancer cell line established using a lentivirus expression system. Epithelial–mesenchymal transition (EMT) was evaluated using qRT-PCR and Western Blots to detect epithelial marker E-cadherin and mesenchymal marker, vimentin. Luciferase reporter assays were used to identify downstream targets and biological function of miR-138. Breast cancer tissues had significantly lower expression of miR-138 compared to non-tumor tissues. Low miR-138 levels were associated with lymph node metastasis and invasion. miR-138 overexpression inhibited metastasis of breast cancer cells. miR-138 overexpression also down-regulated vimentin expression and upregulated E-cadherin expression, suggesting that miR-138 inhibited EMT. Our results support the involvement of miR-138 in breast tumorigenesis, especially lymph node metastasis. We propose that miR-138 might be used as therapeutic agent for breast cancer.