miR-422a Inhibits Glioma Proliferation and Invasion by Targeting IGF1 and IGF1R

Glioma is a common type of malignant brain tumor characterized by aggressive metastasis capability. Recent evidence has suggested that noncoding RNAs, including microRNAs, have important functions in the pathophysiology of glioma development. In this study, we investigated the biological function of miR-422a in human glioma. We found that miR-422a was downregulated in glioma tissues. We also demonstrated that expression of miR-422a in glioma cells markedly suppressed cell proliferation, migration, and invasion. In addition, we identified insulin-like growth factor 1 (IGF1) and IGF1 receptor (IGF1R) as inhibitory targets of miR-422a in glioma cells. We established that the expression levels of miR-422a were negatively correlated with the expression levels of IGF1/IGF1R and the clinical parameters in glioma patients. An IGFR inhibitor, AG1024, completely blocked the activity of miR-442a on glioma cell proliferation and invasion, which further confirmed that miR-422a functions through IGF1 and IGF1R.