Cell cycle and apoptosis alteration of human hepatocarcinoma cells by subclinical-dose 12C6+-beam irradiation.

Objective: The purpose of this study is to investigate the effect of subclinical-dose C-beam irradiation on cell cycle and cell apoptosis in hepatocarcinoma cells.
Materials and Methods: The HepG2 cells were exposed to 0-2.0 Gy of either the C beam or a gamma-ray. Cell survival was detected by clonogenic assay. Cell cycle was determined by flow-cytometry analysis. The apoptosis was monitored by fluorescence microscope with DAPI staining. p53 and p21 expression were detected by Western blot.
Results: The G0/G1 cells in the irradiated groups were significantly more than those in the control (P<0.05). The C-ion irradiation had a greater effect on the cell cycle of HepG2 cells (including promoting G1-phase and G2-phase arrest) than gamma-ray irradiation. The apoptotic cells induced by C beam were significantly more numerous than those induced by gamma-ray (P<0.05). The carbon ions had a stronger effect on p53 and p21 expression than the gamma-ray irradiation. The survival fractions for cells irradiated by C beam were significantly smaller than those irradiated by gamma-ray (P<0.05).
Conclusion: The subclinical-dose C-beam irradiation significantly suppresses HepG2 cells through cell-cycle arrests and cell apoptosis in contrast to same-dose gamma-ray irradiation.