咖啡因对X射线诱导的HL-60细胞凋亡的影响

目的 探讨细胞周期检测点对不同放射剂量射线的耐受性及咖啡因对细胞周期检测点的影响。方法 对数生长期的急性早幼粒白血病细胞株(HL-60)细胞经不同剂量的X射线照射，并加入终浓度为5mmol／L的咖啡因培养4h后．用亚G1峰法检测细胞凋亡，用DNA链缺口标记法(TdT)分析凋亡细胞的细胞周期特异性。结果 不同剂量X射线照射均可诱导HL-60细胞凋亡，2Gy X射线的照射主要诱导G1期细胞凋亡，20Gy X射线照射诱导的细胞凋亡由G1期发展至以S期和G2期为主。加入咖啡因能使射线诱导的细胞凋亡减少，其中2Gy X射线照射的细胞表现为G1期细胞凋亡减少，而20Gy X射线照射的细胞主要表现为以S期和G2期为主的细胞凋亡的减少。结论 细胞对放射剂量的反应性与细胞周期检测点之间存在一定的关系，咖啡因对射线诱导的细胞凋亡及检测点的影响与射线的剂量有关。

Effects of Caffeine on Apoptosis in HL-60 Cells Induced by X-irradiation

Objective To investigate the effects of caffeine on irradiation-induced apoptosis in order to explore the relationships between the cell cycle specific apoptosis and checkpoints and to study the use of caffeine in radiotherapy. Methods The exponential growth HL-60 cells irradiated with X-ray at different doses were incubated for 4 h in the presence of 5 mmol/L caffeine. Then, apoptotic HL-60 cells were analyzed by using Sub-G1 method and TdT method. Results X-irradiation at each dose could induce apoptosis of these cells. 2 Gy X-ray induced cells in G1 phase into apoptosis, while 20 Gy X-ray induced cells to apoptosis from G1 to S and G2 phase. The X-ray-induced apoptotic HL-60 cells were decreased after treatment with caffeine. The decrease was in G1 phase at irradiation of 2 Gy, while the decrease was mainly in S and G2 phase at 20 Gy. Conclusion There existed certain relations between the cell sensibility to the dose of X-irradiation and checkpoint. It also demonstrated that the inhibition of radiation-induced apoptosis and checkpoint by caffeine were related to the dose of irradiation.