RIOK2 is a member of RIO (right open reading frame)
kinase family. Recent studies have revealed the involvement of RIO
kinases in
glioma cell growth and expansion. However, the role and mechanism of RIOK2 in
glioma cell migration and invasion remain unclear. Wound healing assay, Transwell assay and real-time quantitative PCR (qRT-PCR) detection of
matrix metalloproteinases (
MMPs) were used to evaluate the migration/invasion of
glioma cells. Western blot and qRT-PCR were employed to measure the expression of epithelial-mesenchymal transition (EMT) markers. Dual
luciferase reporter assay was performed to determine the binding between RIOK2 and miR-4744. In addition, RIOK2 and miR-4744 levels were quantified by qRT-PCR and/or immunohistochemistry in
glioma tissues. Transfection of RIOK2 siRNAs significantly inhibited
glioma cell migration and invasion and down-regulated the expression of
MMPs (MMP2 and MMP9) and mesenchymal markers (
N-cadherin, β-
catenin, Twist1,
fibronectin, ZEB-1) in
glioma cells. Overexpression of RIOK2 showed the opposite effects. MiR-4744 directly bound to the 3'-untranslated region of RIOK2 and negatively regulated the expression of RIOK2. Up-regulation of miR-4744 inhibited the migration and invasion of
glioma cells. Overexpression of RIOK2 could reverse the effects of miR-4744 up-regulation on the migration, invasion and EMT process in
glioma cells. Moreover, RIOK2 was high, while miR-4744 was low in
glioma tissues, and a negative correlation was found between them. These results suggest that RIOK2 is post-transcriptionally targeted by miR-4744, the low miR-4744 and high RIOK2 levels in
glioma may contribute to tumour cell infiltration through promoting the EMT.