The Regulatory Mechanism Of NF-?B Signal Pathway In Gama Radiation Induced Injuries Of SH-SY5Y Cells

Background: Radiotherapy significantly improves the local control rate of neuroblastoma and the survival rate of patients with neuroblastoma at intermediate-,and high-risk groups.However,radiotherapy doesn't work well in part of patients due to the effect of radiation resistance.What's more,the activation of nuclear factor??B(NF??B)signal pathway plays an important role in that effect.Objective: To research the regulatory mechanism of NF-?B signal pathway in regulating ? radiation induced injuries of SH-SY5 Y cells.Methods: Human SH-SY5 Y cell lines were cultured in DMEM supplemented with10% FBS.Cells were subjected to gamma-radiation with indicated doses(0,0.2,0.5,2,5,10,20 Gy),and then were harvested and subjected to different assays at designated time points after irradiation(4,8,24,48 hours).The SH-SY5 Y cell morphology changes after receiving ? irradiation was observed by inverted microscope.The effect of radiation on the viability of neuroblastoma cell line was examined by mitochondrial dye?uptake assay,apoptosis and cell cycle by flow cytometric analysis,NF??B activation by DNA binding/reporter assays,protein expression by Western blot analysis and gene expression by realtime fluorescence quantitative polymerase chain reaction.Results:(1)Compared with normal SH-SY5 Y cells,radiated cells became swollen,their edges were rough,and their antenna number increased.(2)Compared with control group,the cell numbers of irradiated cells reduced while apoptotic cells and cells in the G2/M phase increased(P<0.01).(3)Compared with control group,the protein expression levels of ?H2ax,p65 and phosphorylated p65,Cleaved Caspase-3 and Parp increased in radiated cells.(4)Compared with control group,the gene expression levels of p65,Pcna,p21,Caspase-3,Bax and Parp increased in radiated cells(P<0.05).(5)Compared with control group,the p65-DNA interaction increased in radiated cells(P<0.05),and the transcription activity of p65 also increased(P<0.01).Conclusion:(1)? radiation activates the NF??B,apoptosis and DNA damage signaling pathway of SH-SY5 Y cells,and then leads to the cell injuries.Radiation induced injuries include cell apoptosis,G2/M cell cycle arrest and inhibition of cell proliferation.(2)NF-?B pathway may promote gamma radiation induced injuries of SH-SY5 Y cells,and p65 is the key transcription factor in that injury effects.