鼻咽癌细胞系CNE-2Z放射敏感性的异质性及其机理探讨

目的　进一步证实人鼻咽癌细胞系CNE 2Z确实存在着放射敏感性的异质性 ,并探讨其有关机理。方法　观察人鼻咽癌细胞系CNE 2Z亚克隆株H5和S1的裸鼠移植瘤放射敏感性的不同 ;用流式细胞仪、荧光显微镜、Western blot检测H5和S1凋亡能力的不同及凋亡相关蛋白表达的差异 ;用3H掺入法说明DNA合成抑制率与放射敏感性的不同 ;用RT PCR观察相关癌基因 (fas、p5 3)的表达与放射敏感性的关系。结果　鼻咽癌细胞系CNE 2Z中确实存在放射敏感性的异质性 ,H5、S1两种细胞的凋亡率都随着照射后时间的延长而增加 ,但H5比S1高且差异有统计学意义 (P <0 0 5 )。两种细胞的DNA合成率于放射前无差别 ;照射后都较放射前受到抑制 (P <0 0 5 ) ,H5受抑制程度大 (P <0 0 5 )。H5与S1细胞fas、p5 3基因的表达差异无统计学意义 (P >0 0 5 )。结论　本实验再次证实了鼻咽癌细胞系CNE 2Z确实存在放射敏感性异质性 ,并证实了其异质性的机理与细胞受射线照射后引起凋亡的能力不同有关、与DNA合成的抑制率成正相关、与癌基因fas、p5 3的表达无关。

Study on radiosensitivity heterogeneity of the NPC cell line CNE-2Z and the related mechanism

Objective To further confirm that the human NPC cell line CNE-2Z indeed has radiosensitivity heterogeneity and to discuss its related mechanism. Methods To observe the difference between sublines H5 and S1 of the cell line CNE-2Z in the radiosensitivity of their transplanted tumors in nude mice, the difference between H5 and S1 in their apoptosis-inducing capacity and that in apoptosis-related protein expression were detected by FCM, fluorescence microscope and Western-blot. The difference in their DNA synthesis inhibition rate and radiosensitivity were expressed by tritium incorporation method. The relationship between the expression of related oncogenes and radiosensitivity was observed by RT-PCR. Results Radiosensitivity heterogeneity did exist in NPC cell line CNE-2Z, and the apoptosis rate of both types of cells, H5 and S1, increased with extension of after-irradiation time, but H5 had a higher apoptosis rate than S1 (P<0.05). There was no difference in DNA synthesis rate between the two cell types; after irradiation, however, the DNA synthesis rate of both cell types was inhibited compared with that before irradiation(P<0.05), especially that of H5 being inhibited to a greater degree (P<0.05). The expression levels of genes fas and p53 of H5 and S2 cells did not have statistical significance (P>0.05). Conclusion The present experiment has once again proved that NPC cell line CNE-2Z indeed has radiosensitivity heterogeneity and also proved that the heterogeneity is related to the capacity of cells in inducing apoptosis after irradiation and is positively correlated with the inhibition rate of DNA synthesis but is unrelated to the expression of oncogenes fas and p53.