Copyright © 2019 Xu et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Clinically, one of the principal factors in the failure of advanced colorectal cancer (CRC) treatment is chemoresistance to 5-fluorouracil (5FU)-based chemotherapy. Although microRNA-375-3p (miR-375) is considered a tumor suppressor in multiple cancers, the mechanism of miR-375 in the regulation of drug resistance in CRC remains unclear. In this study, we investigated the chemosensitivity of miR-375 to 5FU in CRC from biological and clinical aspects. We found that miR-375 was significantly downregulated in CRC tissues and cell lines, and low miR-375 expression was strongly correlated with poor overall survival in CRC patients. Overexpression of miR-375 sensitized CRC cells to a broad spectrum of chemotherapeutic drugs in vitro and in vivo. Further mechanistic analysis demonstrated that miR-375 enhanced CRC cell sensitivity to 5FU by directly targeting YAP1 and SP1. MiR-375 downregulated YAP1, resulting in reduced expression of the Hippo-YAP1 pathway downstream genes CTGF, cyclin D1 and BIRC5 (also known as survivin). Overall, miR-375 was confirmed as a prospective molecular biomarker in the chemoresistance and prognosis of CRC patients, and the synergy between miR-375 and chemotherapeutic drugs could be a promising therapeutic strategy for CRC patients, especially with chemoresistance.