Abnormal miRNA-30e Expression is Associated with Breast Cancer Progression

Background: microRNAs (miRNAs) are involved in the regulation of various cellular processes, such as differentiation, proliferation, metabolism, and apoptosis, and they have been implicated in several diseases, including cancers. Methods: To assess the role of miRNA in the progression of breast cancer, we performed TaqMan-based miRNA profiling for plasma from patients with breast cancer (n = 53), unrelated diseases (n = 40), or matched healthy controls (n = 40), and for breast tumors or adjacent non-tumors (n = 41). Results: We selected 18 miRNAs with predicted roles in breast cancer and demonstrated that let-7i (p = 0.019), let 7a (p = 0.02), and miR-650 (p = 0.008) were significantly up-regulated in plasma; miR-21 (p < 0.001) is up-regulated in breast cancer tissue, and miR-30e was down-regulated in both plasma (p < 0.001) and breast cancer tissues (p = 0.004). Plasma miR-30e expression was shown to be statistically associated with age (p = 0.0402) and clinical stage (p = 0.007). However, receiver-operating characteristic curve analyses suggested that miR-30e expression cannot significantly differentiate breast cancer from healthy tissue or plasma. Consistent with a potential role for miR-30e in breast cancer, three predicted targets of miR-30e (RAB11A, BNIP3L, and RAB32) are up-regulated in breast cancer tissue. Conclusions: These findings suggest that reduced miR-30e correlates with the clinical stage of breast cancer. It is worthwhile to further explore that the potential role of miR-30e as a tumor suppressor in breast cancer, as well as its potential therapeutic utility.