Abstract: Objective  To investigate the effect of microRNA122 （miR-122） on apoptosis of glioma cells and its possible molecular mechanism. Methods The expression of miR-122 in human normal astrocyte lines HA1800 and glioma cell lines U251， U87， SHG44 and MO59K was detected by quantitative fluorescence PCR （QPCR）. Dual luciferase reporter assay was used to evaluate the targeting effect of miR-122 on RUNX2. MiR-122 mimics （miR-122 group）and negative control NC（NC group） were transfected into U251 cells. Apoptosis was detected by flow cytometry. Western blotting was used to detect the expression of Bcl-2，Bax and cleaved caspase-3 protein in two groups. MiR-122 mimics and siRUNX2 （MiR-122+siRUNX2 group） were simultaneously transfected into U251 cells. Apoptosis was detected by flow cytometry. Results The expression of miR-122 in U251，U87，SHG44 and MO59K cell lines were 0.34±0.052， 0.65±0.061， 0.59±0.071 and 0.69±0.098， which was significantly lower than that of human normal astrocyte lines HA1800 （1.17±0.173）， and the difference was statistically significant （P＜0.05）.MiR-122 inhibited the luciferase activity of wild-type RUNX2 3’UTR reporter gene vector， but had no effect on the luciferase activity of mutant RUNX2 3’UTR reporter gene vector. The apoptotic rate of U251 cells in miR-122 group was （23.77 ±0.83）％， higher than that in NC group （6.17 ±0.12）％， lower than that in miR-122+siRUNX2 group （70.85±0.35）％.The difference was statistically significant （P＜0.05）. Western blotting Results  showed that the expression of RUNX2 protein in the miR-122 group was 0.57±0.048， which was lower than that in the NC group （1.21±0.19）， with statistical significance （P＜0.05）. Compared with NC group， the expressions of Bax and cleaved caspase-3 were significantly up-regulated in miR-122 group， while Bcl-2 was significantly down-regulated （P＜0.05）. Conclusion MiR-122 can promote the activation of mitochondrial apoptosis pathway by targeting RUNX2， thereby promoting apoptosis of glioma cells.

Key words: Glioma, miR-122, RUNX2, Apoptosis