Abstract
PURPOSE: Ductal carcinoma in situ (DCIS) contributes to 20%-30% of newly diagnosed cases of breast cancer in China. Although the breast cancer-specific mortality of DCIS is extremely low, a small proportion of DCIS patients still show relapse or metastasis, leading to poor prognosis. Little is known about the molecular mechanism for DCIS metastasis, partly due to the limited number of poor prognosis patients. This study analyzed the clinicopathological features and screened key microRNAs (miRNAs) contributing to local or distant recurrence. METHODS: The clinicopathological features of DCIS were evaluated and survival analysis were performed to clarify risk factors associated with poor prognosis. Using miRNA arrays and real-time quantitative polymerase chain reaction (RT-qPCR) on DCIS formalin-fixed and paraffin-embedded samples with or without microinvasion with different clinical outcomes, potential DCIS metastasis-related miRNAs were screened out and further validated. The influence of one identified miRNA, miRNA-654-5p, on DCIS progression was analyzed. RESULTS: Poor prognosis was significantly associated with larger tumor size and higher lymph node metastasis rate (both p < 0.05). Both were independent prognostic factors for DCIS. According to RT-qPCR results, distinct miRNA expression profiles were identified between DCIS and DCIS with microinvasion (DCIS-Mi) patients. In the DCIS panel, miRNA-654-5p was significantly upregulated in the patients with poor prognosis. In vitro, miRNA-654-5p promoted MDA-MB-231 cell mobility in healing tests and metastasis in the Transwell study. CONCLUSION: The panel of high-risk miRNAs in DCIS and DCIS-Mi differs markedly. miRNA-654-5p is significantly upregulated DCIS patients having poor prognosis and may be essential for local and distant recurrence in DCIS.