Low p21 level is necessary for the suppressive effects of micoRNA-31 on glioma cell migration and invasion.

MicroRNAs (miRNAs), a kind of endogenous non-coding RNAs, regulate gene expression through binding to the 3'-untranslational region (UTR) of target messenger RNAs (mRNAs) and act as endogenous agents of RNA interference, resulting in either mRNA degradation or translational repression. MiR-31 has been demonstrated to be associated with the development and progression of glioma. However, the underlying molecular mechanism remains largely unclear. In the present study, we demonstrated that miR-31 only inhibited the cell migration and invasion, as well as the expression of a known miR-31 target oncogene radixin, in U251 glioma cells that expressed low level of p21; however, miR-31 showed no above effects on glioma SHG44 cells that highly expressed p21. Moreover, upregulation of p21 in U251 cells reversed the suppressive effects of miR-31 on the cell migration and invasion, suggesting that low p21 level is necessary for the miR-31-mediated inhibitory effects on glioma. Furthermore, analysis for 35 glioma specimens showed that the expression of radixin was negatively correlated with the miR-31 level in glioma tissues with low p21 expression; however, no such correlation was found in glioma tissues with high p21 level, further supporting that the low p21 level is necessary for the suppressive effect of miR-31 on the expression of its target oncogenes. In summary, our study demonstrates that the suppressive effect of miR-31 on glioma cell migration and invasion is p21-dependent, and suggests that miR-31 may be used for the treatment of patients with p21-deficent glioma.