MiR-92a promotes stem cell-like properties by activating Wnt/β-catenin signaling in colorectal cancer

We previously reported the oncogenic function of miR-92a in colorectal cancer. This study identified that miR-92a was upregulated in chemoresistant colorectal cancer cells and tissues. Ectopic expression of miR-92a conferred resistance to 5-fluorouracil-induced apoptosis in vitro, while antagomiR-92a significantly enhanced chemosensitivity in vivo. Moreover, Overexpression of miR-92a promoted the tumor sphere formation and the expression of stem cell markers. MiR-92a overexpression also displayed higher tumourigenesis in vivo. Furthermore, we demonstrated that miR-92a upregulates the Wnt/beta-catenin signaling activity via directly targeting KLF4, GSK3 beta and DKK3, which are multiple level negative regulators of the Wnt/beta-catenin signaling cascade. In addition, our results indicate IL-6/STAT3 pathway increases miR-92a expression by directly targeting its promoter, resulting in Wnt/beta-catenin signaling activation and consequent promotion of stem-like phenotypes of colorectal cancer cells. Our present results suggest the essential role of IL-6/STAT3/miR-92a/ Wnt/beta-catenin pathway in regulating the stem cell-like traits of colorectal cancer cells and provide a potential target for colorectal cancer therapy.