RESUMO
Objective To establish the mitochondrial DNA depleted cell line (ρ0 cells) of lung cancer cell A549 and to observe the radiosensitivity difference between ρ0 cells and normal A549 cells (ρ + cells).Methods The ρ0 cells were depleted of mitochondrial DNA by culturing chronically in the presence of low concentration of ethidium bromide (EB),and then the cell model was confined.Radiosensitivity of both ρ0 cells and ρ + cells was detected using the cologenic formation assay.After 6 MV X-ray irradiation in vitro,cell cycle distribution and reactive oxygen species (ROS) level were analyzed by flow cytometry and fluorescence microplate reader,respectively.Results A ρ0 cell line was successfully established and had a lower radiosensitivity than ρ + cells (t =12.57,P ＜ 0.01).After irradiation with a dose of 8 Gy,compared to ρ+ cells,ρ0 cells showed prolonged G2 arrest with less cells in G2 (t =6.82,P ＜ 0.01) and had lower increase of ROS level (t =14.51,P ＜ 0.01).Conclusions ρ0 cells have a lower radiosensitivity than ρ + cells,in which the reduction of ROS production and the prolongation of G2 arrest post-irradiation may be involved.