Role of ATM kinase in the effect of CpG ODN7909 on X-ray-induced G2/M phase arrest and apoptosis in A549 cells / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the relationship between the effect of unmethylated cytosine phosphate-guanine oligodeoxynucleotide ( CpG ODN ) 7909 on X-ray-induced G2/M phase arrest and apoptosis and the phosphorylation of ATM kinase.Methods Human lung adenocarcinoma A549 cells were randomly classified into five groups,control,CpG group,irradiation group,CpG + irradiation group and ATM siRNA + CpG + irradiation group.Cell survival fraction was evaluated by clonogenic assay.Cell cycle and apoptosis were analyzed by flow cytometry.The expressions of ATM,checkpoint kinase-2(Chk2) and p53 were detected with Western blot.Results Compared to the situation under X-ray irradiation alone,decreased cell clonogenic survival,prolonged G2/M arrest,and increased cell apoptosis were observed after the combination treatment with CpG ODN7909 and X-rays ( t =13.41,17.32 and 7.71,P ＜ 0.05).Moreover,the phosphorylations on ATM,Chk2,and p53 were increased in the irradiated A549 cells that had been pre-treated with CpG ODN7909.After ATM siRNA interfering,abrogation of G2/M arrest,reduction of apoptosis,and decrease of Chk2 and p53 phosphorylation were found in A549 cells treated with CpG ODN7909 and X-rays ( t =26.84,2.98,47.24 and 67.47,P ＜0.05).Conclusions CpG ODN7909 can enhance the X-ray-induced phosphorylation of ATM kinase in human lung adenocarcinoma cells in vitro,which might be involved in regulating G2/M phase arrest and apoptosis.