电离辐射诱导EL-4细胞Caspase-3、P53蛋白表达及其生物学作用

Expression of Caspase-3,P53 in EL-4 cells induced by ionizing radiation and its biological implications

目的研究电离辐射对EL-4细胞中Caspase-3和P53蛋白表达的影响，及其对辐射诱导细胞凋亡及多倍体细胞的作用。方法采用单克隆抗体免疫荧光标记及流式细胞术检测蛋白表达的变化，采用PI荧光标记及流式细胞术检测细胞凋亡及多倍体细胞的变化。结果实验表明，4．0GyX射线照射后8及12h，EL-4细胞中Caspase-3蛋白表达与对照组比较，差异有统计学意义（P〈0．05）；照射后2、4、8、12及24h，P53蛋白表达与对照组比较，差异有统计学意义（P〈0．05或P〈0．01）。实验还表明，4．0Gy照射后2、4、8、12、24、48及72h，EL-4细胞凋亡与对照组比较，差异有统计学意义（P〈0．05～P〈0．001）；而照射后2～48h，多倍体细胞数与对照组比较则未见明显变化。结论电离辐射可诱导EL-4细胞Caspase-3及P53蛋白表达增高，可能在辐射诱导细胞凋亡中起重要作用，而辐射诱导多倍体细胞的分子通路则可能是P53非依赖性的。

Objective To investigate the effect of ionizing radiation on the expressions of Caspase-3 and P53 proteins in EL-4 cells and its implications in the induction of apoptosis and polyploid cells. Methods EL- 4 cells were irradiated with 4.0 Gy X-rays （180 kV, 15 mA, 0.287 Gy/min）. Fluorescent staining and flow cytometry analysis were used to measure protein expression, apoptosis and polyploid cells. Results It was found that the expression of Caspase-3 protein was increased significantly at 8 h and 12 h after the irradiation compared with sham-irradiated control （ P 〈 0.05 ）, and the expression of P53 protein was also increased significantly at 2,4,8, 12 and 24 h after the irradiation compared with sham-irradiated control （P 〈 0.05 or P 〈 0.01 ）. The results showed that apoptosis of EL-4 cells was increased significantly at 2,4,8,12,24,48, and 72 h after 4.0 Gy irradiation compared with sham-irradiated control （ P 〈 0.05 or P 〈 0.01 or P 〈 0.001 ）. However, no significant change in the number of polyploidy cells was found during the period from 2 to 48 h after the irradiation with 4.0 Gy X-rays. Conclusions It is indicated that the expressions of Caspase-3 and P53 protein in EL-4 cells can be induced by ionizing radiation, and play an important role in the induction of apoptosis; the molecular pathway for polyploid formation might be P53-independent.