The microRNAs with potential in predicting lung metastasis of triple negative breast cancer

To identify lung metastasis associated microRNAs in triple negative breast cancer (TNBC), we have employed the commercially available Agilent Human miRNA V19.0 Microarray (Platform GPL19730) as a discovery platform. In comparison with LM-Normal, 11 microRNAs significantly altered in both LM-Met and LM-Tumor, and then three of them (hsa-miR-21-3p, hsa-miR-21-5p and hsa-miR-211-3p) were excluded, which were also up-regulated in RF-Tumor. Consequently, eight deregulated microRNAs were identified to be putatively involved in process of lung metastasis, especially miR-629-3p, which was most up-regulated in both LM-Met and LM-Tumor. To validate the microarray data, we utilized qRT-PCR to assess expression levels of the eight miRNAs in the same samples. Four TNBC patients with lung metastasis underwent pulmonary lobectomy, and their matched surgical specimens of lung metastases (LM-Met), primary tumors (LM-Tumor) and normal breast tissues (LM-Normal) were obtained. Furthermore, to preclude the unspecific miRNAs in TNBC, primary tumors (RF-Tumor) and corresponding normal breast tissues (RF-Normal) from another four patients with 10-year recurrence-free survival were also collected. The initial 20 samples from the eight patients were prepared for miRNA profiling. Paired-Sample T Test and Significant Analysis of Microarray (SAM) were used to identify miRNAs with significantly altered expression (fold change > 1.5, p < 0.05). In comparison with Normal, the miRNAs significantly altered in both LM-Met and LM-Tumor, but not in RF-Tumor, was considered as predictive markers for lung metastasis of TNBC.