miR-489 inhibits proliferation, cell cycle progression and induces apoptosis of glioma cells via targeting SPIN1-mediated PI3K/AKT pathway.

microRNA-489 (miR-489), a newly identified tumor-related miRNA, functions as an oncogene or tumor suppressor via regulating growth and metastasis of human cancers. But, the clinical significance, biological function and underlying mechanisms of miR-489 in glioma remain rarely known. Here, we showed that the levels of miR-489 in glioma tissues were notably underexpressed compared to corresponding non-tumor tissues. In accordance, the relative levels of miR-489 were decreased in glioma cell lines compared with NHA cells. Kaplan-Meier plots indicated that miR-489 low expressing glioma patients showed a prominent shorter overall survival. In addition, miR-489 overexpression prohibited proliferation and cell cycle progression, and promoted apoptosis in U251 cells. While, miR-489 knockdown showed opposite effects on these cellular processes of U87 cells. In vivo experiments demonstrated that miR-489 restoration reduced the tumor volume and weight of subcutaneous glioma xenografts in nude mice. Notably, Spindlin 1 (SPIN1) was inversely and directly regulated by miR-489 in glioma cells. A negative correlation between the expression of miR-489 and SPIN1 mRNA was confirmed in glioma tissues. Interestingly, miR-489 inversely modulated activation of PI3K/AKT pathway and expression of downstream targets including p-mTOR, Cyclin D1 and BCL-XL. SPIN1 re-expression abolished the effects of miR-489 on U251 cells with enhanced activation of PI3K/AKT pathway and malignant phenotype. Meanwhile, AKT inhibitor MK-2206 blocked activation of PI3K/AKT pathway and resulted in reduced proliferation, cell cycle arrest and increased apoptosis in miR-489 down-regulating U87 cells. Altogether, our data support that miR-489 loss facilitates malignant phenotype of glioma cells probably via SPIN1-mediated PI3K/AKT pathway.