人鼻咽癌细胞株CNE1和CNE2放射生物学特性及MRN复合体表达的研究

Radiobiological characteristics and MRN complex expression of human nasopharyngeal carcinoma cell lines

目的探讨人鼻咽癌细胞株CNE1和CNE2的放射生物学特性及其MRN（Mrell一Rad50．Nbs1）复合体放射线照射前后的表达改变。方法电子直线加速器照射对数生长期CNE1和CNE2细胞，克隆形成实验和四甲基偶氮唑蓝（MTI＂）法绘制细胞增殖曲线了解两株细胞的放射生物学特性；免疫印迹实验检测两株细胞MRN复合体天然表达及放射线照射后表达情况。结果CNE1细胞株的2Gy照射后存活分数（survival fraction at2Gy，SF2）、准阈剂量（quasi—threshold dose，Dq）和平均致死剂量（rtlean lethal dose，Do）分别为0．56、1．449Cy和1．480Gy；CNE2细胞株的SF2、Dq和Do分别为0．44，0．776Gy和1．685Gy。4Gy放射线照射后两株细胞增殖曲线与对照组相比差异有统计学意义（F=881．70，F=858．18，P值均〈0．05），至第6天时CNE1存活分数为0．59，CNE2为0．79。Westernblot法显示两株细胞均天然表达MRN复合体3个组分（Mrell，Rad50，Nbs1）；4Gy放射线照射后，CNE1细胞Rad50蛋白表达上调（t=8．13，P〈0．05），CNE2细胞Mrell、Rad50和Nbs1蛋白表达均上调（t值分别为5．54，9．49和13．08，P值均〈0．05）。结论CNE1和CNE2细胞株均对放射线照射总体敏感，但本株CNE2中可能存在对放射线照射抵抗的亚群；CNE1和CNE2细胞均天然表达MRN复合体，放射线照射后，两株细胞均上调MRN复合体组分的表达进行损伤修复。

Objective To study the radiobiological characteristic of human nasopharyngeal carcinoma cell lines CNE1 and CNE2 and the changes in expression MRN （Mrel 1- RadS0- Nbsl ） complex in the cell lines exposed to irradiation. Methods CNE1 and CNE2 were irradiated by a linear accelerator. Radiobiological characteristics were detected by colony assay and MT＇F assay. MRN complex expression were examined by Western blot. Results Surviving fraction at 2 Gy （SF2） , quasi-threshold Dose （ Dq）, and mean lethal dose （Do） of CNE1 were 0.56, 1.449 Gy and 1.480 Gy; SF2, Dq, and Do of CNE2 were 0. 44, 0.776 Gy and 1. 685 Gy, respectively. Survival fraction of CNE1 at the day 6 after 4 Gy irradiation was 0.59 and that of CNE2 was 0.79 when compared with control, with the up-regulated expressions of RadS0 in CNE1 and Mrell, RadS0 and Nbsl in CNE2 （P 〈0.05）. Conclusions CNE1 and CNE2 were sensitive to radiation, but there were radioresistance cells in CNE2. The expressions of some components of MRN complex were up-regulated to repair DNA lesions induced by radiation.