MicroRNA-128 inhibits proliferation and invasion of glioma cells by targeting COX-2.

MicroRNAs (miRNA), a class of small noncoding RNAs, regulates message RNA (mRNA) by targeting the 3'-untranslated region (3'-UTR) resulting in suppression of gene expression. In this study, we identified the expression and function of miR-128, which was found to be downregulated in glioma tissues and glioma cells by real time PCR. Overexpression of miR-128 mimics into LN229 and U251 cells could inhibit proliferation and invasion of glioma cells. However, the inhibitory effects of miR-128 mimics on the invasion and proliferation of glioma cells were reversed by overexpression of cyclooxygenase-2 (COX-2). Our data showed that COX-2 was a candidate target of miR-128. Luciferase activity of 3'-UTR of COX-2 was reduced in the presence of miR-128. Additionally, miR-128 obviously decreased COX-2 mRNA stability determined by real time PCR. Contrarily, we found that miR-128 inhibitor significantly increased the COX-2 mRNA expression, and elevated the protein expression of MMP9 and ki67, and promoted the proliferation of glioma cells. Furthermore, luciferase activity of the 3'-UTR was upregulated by miR-128 inhibitor. All of these results supported that miR-128 was a direct regulator of COX-2. Further studies proved that COX-2 was elevated in glioma tissues and its expression was negatively correlated with the levels of miR-128. These findings may establish miR-128 as a new potential target for the treatment of patients with gliomas.