Eribulin Treatment Induces High Expression of miR-195 and Inactivates the Wnt/β - catenin Signaling Pathway in Triple-negative Breast Cancer

Abstract

Triple-negative breast cancer （TNBC） accounts for 10-15％ of all breast cancer cases and shows a poor prognosis with 30％ distant metastasis. With few specific target molecules and ineffective hormonal and anti-HER2 treatment, an alternative therapeutic method for TNBC is urgently required. Recently, a non-taxane inhibitor of microtubule dynamics called eribulin was developed for breast cancer therapy. Eribulin induces irreversible mitotic mass formation in cancer cells during the G2-M phase, initiating apoptosis; however, the mechanism underlying this eribulin activity remains unclear. We reported previously that exposing non-basal-like （NBL） TNBC cells to eribulin increases miR-195 expression, which in turn decreases the expression of targeted Wnt3a. The present study sought to further clarify the mechanism of this antitumor effect by exploring how eribulin affects Wnt/β - catenin signaling based on miRNA expression changes in TNBC. In an NBL type of human breast cancer cell line （MDA-MB-231 cells）, we compared the expression levels of Wnt/β catenin signaling pathway proteins in cells exposed to an miR-195 mimic （cells transfected with miR-195 and in which Wnt3a expression was suppressed） and in cells exposed to eribulin. Expression levels of Wnt3a, β -catenin, and GSK-3β were measured by ELISA and observed by fluorescence immunostaining. Wnt3a and β -catenin expression was significantly lower and GSK-3β expression was significantly higher in the cells exposed to eribulin and transfected with miR-195 mimic than in the untreated controls, suggesting that eribulin inactivates the Wnt/β -catenin signaling pathway. Therefore, a novel antitumor mechanism of eribulin was determined, whereby eribulin induces high expression of miR-195 to inactivate the Wnt/β -catenin signaling pathway in NBL-type TNBC.