Radiosensitivity and cell cycle of HepG2 hepatoma cell line irradiated by ionizing radiation with different linear energy transfer

In this paper, the effect of the ionizing radiation with different linear energy transfer on radiosensitivity, cell cycle alteration and the change of apoptosis in HepG2 hepatoma cell lines are studied to build up the base data for clinical therapy. Exponentially growing HepG2 cell lines are irradiated by 12C6+ ions and X-ray at the doses of 0, 0.5, 1, 2, 4 and 8 Gy, respectively. The radiosensitivity is assessed by means of the colony-forming assay. The DNA content, percentage of each cell-cycle phase and the apoptosis rate are obtained with the flow cytometry methods. The results indicate that compared with X-ray, the survival fraction of HepG2 hepatoma cells irradiated by 12C6+ ions is evidently lower, the S phase arrest, G2/M phase arrest delay and the apoptosis in HepG2 cells irradiated by 12C6+ ions are more prominent with the increase of dose and repaired time, thus suggesting that 12C6+ ions can more effectively kill the HepG2 cells and induce apoptosis in the cells than X-ray. (authors)