Correlativity study between expression of DNA double-strand break repair protein and radiosensitivity of tumor cells

DNA double-strand break(DSB)is generally regarded as the most lethal of all DNA lesions after radiation.Ku80,DNA-PK catalytic subunit(DNA-PKcs)and ataxia telangiectasia mutated(ATM)proteins are major DSB repair proteins.In this study,survival fraction at 2Gy(SF2)values of eight human tumor cell lines(including four human cervical carcinoma cell lines HeLa,SiHa,C33A,Caski,three human breast carcinoma cell lines MCF-7,MDA-MB-231,MDA-MB-453,and one human lung carcinoma cell line A549)were acquired by clone formation assay,and western blot was applied to detect the expressions of Ku80,DNA-PKcs and ATM protein.The correlativity of protein expression with SF2 value was analyzed by Pearson linear correlation analysis.We found that the expression of the same protein in different cell lines and the expression of three proteins in the same cell line had a significant difference.The SF2 values were also different in eight tumor cell lines and there was a positive correlativity between the expression of DNA-PKcs and SF2(r=0.723,P=0.043),but Ku80 and ATM expression had no correlation with SF2(P>0.05).Thesefindings suggest that the expression level of DNA-PKcs protein can be an indicator for predicting the radiosensitivity of tumor cells.