Up-regulation of miR-663a inhibits the cancer stem cell-like properties of glioma via repressing the KDM2A-mediated TGF-β/SMAD signaling pathway.

Emerging reports have shown that microRNAs (miRNAs) function as vital regulators in tumor development via modulating gene expression at the posttranscriptional level. Here, we explored the role and underlying mechanism of miR-663a in the proliferation, migration, invasion, and cancer stem cell-like (CSC) properties of glioma cells. Quantitative reverse transcription PCR (qRT-PCR) was implemented to detect miR-663a expression in glioblastoma tissues and the adjacent normal tissues. Additionally, gain- and loss-of-function assays of miR-633a were performed on U-251 MG cells or human primary glioblastoma cancer cells (pGBMC1). Cell proliferation, migration, invasion, CSC properties, and profiles of stem cell markers (including CD133, CD44) were examined by the MTT assay, Transwell assay, tumorsphere experiment, and Western blotting, respectively. The dual-luciferase reporter gene assay was performed to testify the targeted relationship between miR-663a and lysine demethylase 2A (KDM2A). The results showed that miR-663a was down-regulated in glioblastoma tissues and cells. Overexpressing miR-663a repressed the proliferation, migration, invasion, CSC properties of U-251 MG cells and pGBMC1, while miR-663a knockdown had the opposite effects. The in-vivo experiment confirmed that miR-663a repressed the growth of U-251 MG cells in nude mice. When cocultured with THP1 cells, U-251 MG cells gained enhanced proliferation, migration, invasion, and CSC properties. MiR-633a overexpression reversed THP1-mediated effects on U-251 MG cells, and reduced the "M2" polarization of THP1 cells. What's more, Mechanistically, KDM2A was targeted by miR-663a. KDM2A knockdown suppressed the progression and CSC properties of U-251 MG cells in vitro, and dampened TGF-β. Overall, those data revealed that up-regulating miR-663a reduced glioma progression by inhibiting the KDM2A-mediated TGF-β/Smad pathway.