Abstract
BACKGROUND: MicroRNAs (miRNAs) play pivotal roles in the development and progression of breast cancer (BC). In this study, we attempted to identify miRNAs associated with BC prognosis and progression via integrated analysis. METHODS: We first screened 83 differentially expressed miRNAs (DEMs) in 1249 BC samples and 151 normal samples. We then validated their roles in expression and prognosis of BC, identified two survival-related DEMs, and established a risk model. The prediction efficiency was assessed in both the training and validation groups. Tissue and cell experiments were conducted to verify the regulatory effects of miR-127 in BC. RESULTS: The ROC curve indicated good prediction ability with 1-, 3-, and 5-year survival rates of 0.73, 0.72, and 0.72, respectively. Moreover, hsa-miR-127 was found to be an independent prognostic factor of BC. Functional analyses revealed that it is involved in various cancer pathways such as the PI3K-Akt and p53 pathways. miR-127 expression was down-regulated in both BC tissues and cell lines. The knockdown of miR-127 substantially increased, whereas overexpression decreased BC cell proliferation, invasion, and migration. This effect of miR-127 was consistent with its tumorigenic ability and tumor volume in nude mice. CONCLUSIONS: These findings indicate that low expression of miR-127 contributes to BC migration, invasion, and tumorigenesis and that it can be a therapeutic target and prognostic biomarker for BC.