Dose-rate effect of adaptive response of apoptosis and cell cycle progression induced by low-dose ionizing radiation in EL-4 lymphoma cells in vitro

Objective To observe the dose-rate effect of adaptive response of apoptosis and cell cycle progression induced by low-dose ionizing radiation in EL-4 lymphoma cells in vitro in order to reveal the possible mechanism of biological effect and adaptive response induced by low dose radiation. Methods The experiment was divided into D2 (challenging dose),D1 (inductive dose) + D2 and sham-irradiation groups.EL-4 lymphoma cells were irradiated with D1 (75 mGy,6.25-200.00 mGy·min-1) and D2 (1.5 Gy,287 mGy·min-1),the time interval between D1 and D2 was 6 h. The percentage of apoptosis and each cell cycle phase were measured with flow cytometry.Results When the dose rates of D1 were 6.25-50.00 mGy·min-1,the percentages of apoptosis in the D1 + D2 group were significantly lower than those in the D2 group (P0.05);meantime,the percentages of G0/G1 phase cells decreased significantly (P0.01),and the percentages of S phase cells increased at different degrees.Conclusion When the dose rates of D1 (75 mGy) are 6.25-50.00 mGy·min-1,D2 is 1.5 Gy (287 mGy·min-1),and the time interval between D1 and D2 is 6 h,the adaptive response of apoptosis and cell cycle progression in EL-4 lymphoma cells in vitro could be induced.