Abstract:

Abstract:Objective
To observe the influence of microwave radiation in the apoptosis of human neuroblastoma SH-SY5Y cells and explore its mechanism. Methods Regarding 0 mW·cm^-2 as sham radiation group，the SH-SY5Y cells were radiated for 5 minutes by 10,30 and 50 mW·cm^-2 of microwave. The morphological changes of cells were observed under  light microscope;the cell nucleus stained by DAPI were observed under fluorescence microscope;the cell genomic DNA was extracted by CTAB and electrophoresed to observe DNA ladder;the cell viability was detected by trypan blue exclusion assay;the apoptotic rate was detected by flow cytometry with annexin V-FITC/PI double staining;the relative activity of cells was detected by MTT assay;the expressions of apoptosis-related proteins were detected by Western blotting. Results After microwave radiation,the morphology of SH-SY5Y cells changed immediately,the nucleus and cytoplasm structure were less clear,and cell shrinkage or even off the wall were observed;chromatin in the nucleus appeared irregular condensation,and fragmentated into 2 to 5 micronuclei;cell DNA ladder was apparent. The survival rate of SH-SY5Y cells was reduced gradually with the increasing of microwave radiation intensity,there was no significant difference between 10 mW·cm^-2 radiation group and sham radiation group (P>0.05);however,the cell survival rates in 30 and 50 mW·cm^-2 radiation group were lower than that in sham radiation group(P<0.05). The apoptotic rate of SH-SY5Y cells was gradually increased with the microwave radiation intensity in 6 h after microwave radiation,and the apoptotic rates in  each radiation group were higher than that in sham radiation group(P<0.05). Compared with sham radiation group,the cell relative activities of SH-SY5Y cells in each radiation group were markedly decreased  24 and 48 h after microwave radiation(P<0.05),and they were decreased with the increasing of microwave radiation intensity. After microwave radiation,the expressions of apoptosis related proteins Bcl-2 and survivin were decreased,the expressions of Bax,Caspase-3 and Caspase-7 were increased gradually,but the expressions of Caspase-8 and Caspase-9 changed little. Conclusion The apoptosis of SH-SY5Y cells can be induced by microwave radiation in a obvious dose-dependent manner,which may be related to the increase of Survivin and Bcl-2 proteins,the decrease of Bax protein and the action of the Caspase-3 and Caspase-7,but with little relationship of the activation of Caspase-3 mediated by caspase-8 and Caspase-9.

Key words: microwave radiation;human neuroblastoma, SH-SY5Y cells;apoptosis