Differential biological effects of ultra-high dose rate irradiation on BEAS-2B and A549 cells

Objective Comparative analysis of the differential effects of Ultra High Dose Rate (UHDR) and conventional dose rate electron beam irradiation on normal and tumor cells.Method Using a 6MeV electron beam linear accelerator, normal cell line (BEAS-2B) and tumor cell line (A549) were irradiated separately to establish a control group, conventional (CONV) irradiation group, and UHDR irradiation group; Using CCK8 experiment to detect the effects of different dose rates of irradiation on the survival ability of normal cells and tumor cells; Determine oxidative damage by measuring the levels of SOD and MDA in cells after irradiation; Immunofluorescence assay is used to detect double stranded DNA breaks and repair in cells, while flow cytometry is used for cell cycle detection.Results After exposure to 6 Gy and 15 Gy of CONV and UHDR irradiation, the survival rate of BEAS-2B cells in the UHDR group was significantly higher than that in the CONV group (F=12.73, P<0.05; F=13.92, P<0.05; F=38.07, P<0.05; F=38.94, P<0.05), and the survival rate of BEAS-2B cells as normal cells was higher than that of A549 cells (F=8.198, P<0.05; F=19.21, P<0.05; F=34.97, P<0.05; F=19.24, P<0.05); After CONV irradiation, the SOD activity and MDA content of BEAS-2B and A549 cells were significantly changed. The SOD activity of BEAS-2B cells changed slightly after UHDR irradiation, and the difference was not statistically significant compared with the non-irradiated group. The SOD activity of A549 cells in the UHDR group was not statistically different from that in the CONV irradiation group. The MDA content of BEAS-2B cells in the UHDR irradiation group was lower than that in the CONV group (F=88.98， P<0.05； F=63.70， P<0.05； F=34.27， P<0.05； F=95.16， P<0.05 ). Compared with the CONV irradiation group, there was no significant difference in the MDA content of A549 cells after UHDR irradiation; Compared with CONV, after UHDR irradiation, BEAS-2B cells showed stable G2 phase arrest at 24-72 hours, while A549 cells showed a high proportion of G1 phase arrest at 4 hours, but cell cycle collapse at 72 hours; After 4 hours of irradiation, the UHDR group showed less formation of gamma H2AX foci in BEAS-2B cells compared to the CONV group, and the gamma H2AX foci significantly decreased after 24 hours. After UHDR irradiation, the number of DNA double-strand breaks was reduced, and they were repaired more quickly.Conclusion After UHDR irradiation, the radiation damage to lung epithelial-like cells BEAS-2B in terms of survival, oxidative damage, cell cycle, and DNA damage repair is less than that of conventional dose rate irradiation.