The Study Of MiR-21 On The Radiosensitivity Of Human Glioma Cell Line SHG-44 And Its Mechanism

Objective:To observation miR-21 differential expression in the model of radioresistant glioma SHG-44 cells and SHG-44 cells,and investigate the radiosensitizing effect of knock-down the expression of miR-21 by antisense oligonuleotides of miR-21(AS-miR-21) on human SHG-44 glioma cells.Methods:Radioresistant cell model(SHG-44R) were established from SHG-44 glioma cells line Then the radiosensitivity of SHG-44 and SHG-44R were studied by clonogenic assay.Multi-target single-hit model were used to plot the survival curve. Meanwhile,expression levels of miR-21 in SHG-44R and SHG-44 were determined by quantitative real time PCR(qRT-PCR). Stat3 protain were detected by western blot.As-miR-21,mediated by LipofectamineTM2000,were transfected to SHG-44 cells.Three groups were studied:blank control group(mock group),negative control and Antisense transfected group(AS-miR-21 gorup). Cells of each group were irradiated with 6 MV X-ray at the dose of 0,1,2,4,6 and 8 Gy.Dose-Suvivial curve of each group was established by colony-forming assay.The influence of AS-miR-21 on cell cycle and cell apoptosis was analyzed by flow cytometry assay after 6 Gy irradiation.Morphology feature of apoptosis was observed by laser confocal micorscope in SHG-44 cells stained with AO/EB.Results: miR-21 was up-regulation 1.49 fold in SHG-44R cells relative to the SHG-44 cells. The up-regulation of miR-21 expression was shown to be associated with a increase in the level of stat3 protein。The value of D0,Dq and SF2 of AS-miR-21 group declined obviously compared with the mock group and negative control group.Flow cytometric analysis showed that cell cycle distribution changed(G0+G1 phase arrest,S phase decreased) after transfected with AS-miR-21(P<0.05).Apoptosis assay showed the early apoptosis rate was significantely increased in AS-miR-21,irradition alone and combined group than mock or negative control group(P<0.05).Conclusions:miR-21 may represent a new molecular target and may provide a basis for the use of the AS-miR-21 as potential radiosensitizers for treatment of the glioma tumors.