低剂量辐射诱导EL-4淋巴瘤细胞凋亡及细胞周期进程适应性反应的时间效应

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

目的：研究低剂量辐射诱导EL-4淋巴瘤细胞凋亡及细胞周期进程适应性反应的时间效应，以揭示低剂量辐射生物效应及其诱导适应性反应的可能机制。方法：实验分D2组（攻击剂量）、D1（诱导剂量）＋D2组和假照组。用X射线照射离体EL-4淋巴瘤细胞，其D1为75mGy（剂量率12．5mGy·min^-1），D2为1．5Gy（剂量率287mGy·min^-1），D1和D2间隔为3～60h。通过流式细胞仪检测其细胞凋亡和细胞周期进程的变化。结果：当D1和D2间隔为3～24h时，D1＋D2组细胞凋亡百分数明显低于D2组（P〈0．05或P〈0．01），G0／G1期细胞百分数不同程度低于D2组，而S期细胞百分数明显高于D2组（P〈0．05）。结论：75mGy（12．5mGy·min^-1）照射后3～24h，进行1．5Gy（287mGy·min^-1）照射，可诱导体外EL-4淋巴瘤细胞凋亡和细胞周期进程的适应性反应。

Objective To study the time effect of adaptive response of apoptosis and cell cycle progression induced by low-dose ionizing radiation in EL-4 lymphoma cells in vitro 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） group, D1 （inductive dose） ＋D2 group and sham-irradiation group. EL-4 lymphoma cells were irradiated withD1 （75 mGy, 12,5 mGy, min^-1） andD2 （1,5 Gy, 287 mGy· min^-1）, the interval time betweenD1 andD2 were 3-60 h, The cell percentages of apoptosis and each cell cycle phase were measured with flow cytometry. Results When the time intervals between D1 and D2 were 3-24 h, the percentages of apoptotie cells in D1＋D2 group were significantly lower than those in D2 group （P〈0.05 or P〈0. 01） ; meantime, the percentages of G0/G1 phase cells decreased in varying degrees, and the percentage of S phase cells increased significantly （P〈 0. 05）, Conclusion The adaptive response of apoptosis and cell cycle progression in EL-4 lymphoma cells in vitro could be induced by irradiation with 75 mGy （12. 5 mGy · min^-1） at 3-24 h before 1, 5 Gy （287 mGy · min^-1） exposure.