MicroRNA-940 inhibits glioma progression by blocking mitochondrial folate metabolism through targeting of MTHFD2

The aggressiveness and recurrence of glioma are major obstacles for the treatment of this type of tumor. Further understanding of the molecular mechanisms of glioma is necessary to improve the efficacy of therapy. MicroRNAs have been widely studied in many human cancers. Here, we found that miR-940 was one of the primary downregulated miRNAs in clinical samples and glioma cell lines through bioinformatics analysis and qRT-PCR. Upregulating miR-940 expression significantly inhibited the proliferation and invasion and promoted apoptosis of U87 and U118 cells. In addition, experiments in vivo showed that upregulation of miR-940 expression inhibited xenograft growth. Methylenetetrahydrofolate dehydrogenase (MTHFD2), a dual-functional metabolic enzyme, is involved in the one-carbon metabolism of folate in mitochondria. We found MTHFD2 to be overexpressed in glioma tissues and our clinical samples by qRT-PCR and Western blot assays. Through TargetScan prediction and luciferase assays, we found that miR-940 directly targets MTHFD2. Upregulation of miR-940 expression inhibited the expression of MTHFD2 and led to intracellular one-carbon metabolism dysfunction. Furthermore, the antitumor effects of miR-940 could be attenuated by overexpression of MTHFD2. Together, the results of our study suggest that miR-940 may be a new therapeutic target for the treatment of glioma through targeting of MTHFD2.