Cell-killing induced by 125 I seeds in CL187 cell line

Objective To study the response patterns of CL187 cell lines irradiated with low dose rates of 125I seeds.Methods CL187 cells were exposed with radioactive.125I seeds and 60Co source,which were put under culture plate.The radiation response at different doses and dose-rates were evaluated through cell-proliferation assessed by the colony-forming assay and death rate after irradiation.Meanwhile,cell cycle arrest and apoptosis were measured by flow cytometry after 2,5 and 10 Gy of low dose rate irradiation.Remits It was shown that the cell-killing effects were related to the doses and dose-rates.At 1 Gy,comparison of the death rate between the low and high dose rate showed that the higher dose rate led to increased cell responses,but at the doses higher than 2 Gy,the effect of the low dose rate were more efficient.At the same dose,the survival fraction of 125I was always lower than that of 60Co.Exposed to the low dose rate irradiation,apoptosis and G2/M cell cycle arrest rose a little at 2 Gy,the peak appeared at 5 Gy,and the ratio at 10 Gy Was also high but lower than at 5 Gy.Furthermore,the G2/M cell cycle arrest and apoptosis changed together along with the doses.Conclusions At the same dose,125I seeds have more cell-killing effects than 60Co at high dose rate irradiation.Apoptosis following the G2/M cell cycle arrest were the main mechanism of cell-killing effects under low dose rate irradiation. Key words: 125I seeds; Cell cycle arrest; Apoptosis