microRNA-217 inhibits tumor progression and metastasis by downregulating EZH2 and predicts favorable prognosis in gastric cancer

microRNA-217 (miR-217) is frequently dysregulated in cancer. Here, we report that miR-217 levels were lower in tumor tissue compared with the adjacent normal tissue. Low levels of miR-217 were associated with aggressive tumor phenotypes and poor overall survival in gastric cancer patients. The ectopic expression of miR-217 inhibited cell proliferation, migration and invasion in vitro and tumor growth and metastasis in vivo, whereas knockdown of endogenous miR-217 increased cell proliferation and invasion. Further experiments revealed that Polycomb group protein enhancer of zeste homolog 2 (EZH2) was a direct target of miR-217 in gastric cancer cells. Knockdown of EZH2 mimicked the tumor-suppressive effects of miR-217 in gastric cancer cells, whereas the reintroduction of EZH2 abolished its effects. Taken together, these results demonstrated that miR-217 may be used as a prognostic marker, and the newly identified miR-217-EZH2 axis may be a potential target in the development of therapeutic strategies for gastric cancer patients.