模拟IMRT模式下相对剂量率变化对CNE-2细胞周期及Cyclin D1、Cyclin B1蛋白表达的影响

目的探讨模拟调强放射治疗（intensity-modulated radiation therapy IMRT）对人鼻咽低分化鳞癌细胞株（CNE-2）细胞周期及Cyclin D1、Cyclin B1蛋白水平的影响。方法选取CNE-2为实验对象,分为空白对照组、急速照射组（acute radiation AR）及模拟IMRT（simulational intensity-modulated radiation SIMR）组,后2组分别给予6MV-X线2、4、6、8 Gy 4个剂量点的照射。急速照射组完成时间1-3分钟;模拟IMRT组：各个剂量点分别等分分割5次,每次间隔8-8.5分钟,总时间35分钟照射完成。应用流式细胞术（FCM）分析细胞周期再分布的差异;应用Western blotting检测细胞周期相关因子Cyclin B1、Cyclin D1的蛋白水平。结果在相同剂量点,模拟IMRT组G2期细胞比例低于急速照射组,G2期细胞比例随照射剂量的增加而逐渐增加。急速照射与模拟IMRT组不同剂量点之间以及在相同剂量点比较,Cyclin D1的蛋白表达差异均无统计学意义（P值均〉0.05）;Cyclin B1的蛋白表达差异均有统计学意义（P值均〈0.05）,且随照射剂量的增加而下降,模拟IMRT组Cyclin B1的表达高于急速照射组。结论模拟IMRT照射时间延长,对G2期阻滞作用下降,细胞周期素Cyclin B1的表达相对升高。

Cell cycle redistribution in human nasopharyngeal carcinoma cell line CNE-2 with simulative IMRT in vitro

Objective To investigate the cell cycle and expressions of Cyclin B1,Cyclin D1 in human nasopharyngeal carcinoma cell line with simulative intensity-modulated radiation therapy（SIMRT）.Methods Single cell suspension was prepared from CNE-2 cells with exponential growth phase and divided into three groups：in control group the cells were not irradiated,in acute radiation（AR） group the cells were irradiated with 2,4,6,8 Gy by 6 MV X-ray at 3Gy/min within 1 to 3 min;in SIMR group cells were irradiated with same dose for 35 min.Cellular cycle of CNE-2 cells was observed by flow cytometry（FCM）;the expressions of Cyclin B1 and Cyclin D1 were detected by Western blotting.Results Compared to AR group,the G_2 phase in SIMRT group was lower in each dose levels.The expression of Cyclin B1 protein in SIMRT group was higher than that in AR group in each dose levels（P〈0.05）;however for Cyclin D1 there was no significant difference between two groups（P〉0.05）.And the expression of Cyclin B1 in both groups was down-regulated in a dose-dependent manner（P=0.000）.Conclusion SIMRT leads to higher expression of Cyclin B1 and lower G2 phase of cell cycle.