Aberrant miR-215 expression is associated with clinical outcome in breast cancer patients.

Dysregulation of microRNA plays critical roles in various malignancies. However, whether the aberrant expression of miR-215 in breast cancer is associated with malignancy, metastasis, or prognosis remains unknown. In this study, we demonstrated that the relative level of miR-215 expression was lower in cancer tissues compared with adjacent non-malignant tissues (p < 0.001). Low-miR-215 expression was observed to be closely correlated with higher tumor grade (p = 0.008), human epidermal growth factor receptor 2 (HER2) positivity (p = 0.006), HER2 positive breast cancer subtype (p = 0.016), and lymph node metastasis (p = 0.039). Moreover, patients with low-miR-215 expression showed shorter 5-year disease-specific survival (DSS) than the high-miR-215 expression group (p = 0.007). Multivariate analysis results revealed that miR-215 downexpression was an unfavorable prognostic factor for DSS in addition to tumor size, ER, and lymph node metastasis. Our results support the potential of miR-215 as a prognostic predictor for breast cancer with its high expression in cancer tissues and its relationship with other clinicopathologic factors and survival.