Changes of cell-cycle progression of different types of tumor cell lines induced by 3Gy γrays

Exponentially growing human tumor cell lines were γ -irradiated with a dose of 3Gy. The DNA content and percentage of each cell-cycle phase were obtained with flow cytometry. Results indicated that for SMMC-7721, hepG2 and HO-8910 cells, G2/M accumulation was prominently induced by irradiation and the maximal accumulation appeared at 12 h after treatment, and that S phase just displayed temporal accumulation, i.e. S phase cells accumulated at 6 h after irradiation, and thereafter decreased close to or below the level of un-irradiated cells, and that for Hela cells both G2/M and S phase accumulation were pronouncedly triggered by irradiation. It is suggested that there remain differences in activation and maintenance of cell cycle checkpoints after irradiation among these four tumor cell lines.