Tumor suppressor role of miR-217 in human epithelial ovarian cancer by targeting IGF1R.

Accumulating evidence shows that microRNA-217 (miR-217) is frequently dysregulated in various cancers, and plays crucial roles in tumorigenesis and metastasis; however, the role and underlying molecular mechanism of miR-217 in human epithelial ovarian cancer (EOC) remains unclear. Here, we report that miR-217 expression was downregulated in EOC tissue and inversely correlated with advanced FIGO stage, high histological grading and lymph node metastasis (P<0.01). Function analysis revealed that the ectopic expression of miR-217 in EOC cells inhibited cell proliferation, migration and invasion in vitro, as well as suppressed tumor growth in vivo. Bioinformatics analysis and dual luciferase assays identified insulin-like growth factor 1 receptor (IGF1R) as a direct target of miR-217 in EOC cells. Western blot assay showed that overexpression of miR-217 in EOC cells inhibited IGF1R expression. In addition, downregulation of IGF1R mimicked the tumor-suppressive effects of miR-217 in EOC cells, whereas the reintroduction of IGF1R partially abrogated the suppression effect induced by miR-217 on EOC cells. Collectively, these results demonstrated that miR-217 plays a tumor suppressor role in human epithelial ovarian cancer by directly targeting IGF1R gene, suggesting a new potential therapeutic target in EOC.