Effects of low dose 12C6+ ion beam pre-irradiation on DNA damage and cell cycle progression in mice liver

To investigate effects of low dose heavy ions pre-irradiation on radiation damage in mice liver, Kun-Ming strain mice were irradiated to 0,0.05,0.1,0.25 or 0.5 Gy of 12C6+ ions, respectively, at a dose rate of 0.2 Gy/min. Four hours later,the mice were irradiated to 4 Gy by 12C6+ ions. At 8 h after irradiation, the cell cycles of liver cells were analyzed by FACS, and the degree of DNA damage was measured by single cell gel electrophoresis through the determination of cells frequency with tail moment and tail lengths. The results indicated that compared with irradiation control group of 4 Gy, the percentages of cells after pre-exposure with low-dose 12C6+ ions at G0/G1-phase and G2/M-phase on liver decreased significantly, whereas the percentages of S-phase cells increased. Similarly, the tail length and tail moment induced by 12C6+ ion beams irradiation decreased evidently (P < 0.01 or P < 0.05), especially the 0.1 Gy pre-exposure group (P < 0.01). The data showed that pre-exposure with low-dose heavy ions could induce the adaptive response in liver cells of mice, alleviate the G0/G1 and G2/M phase arrest and reduce the DNA damages remarkably induced by 12C6+ ion beams. (authors)