“彗星”分析法检测鼻咽癌细胞DNA放射损伤与修复

目的　探讨“彗星”分析法(CometAssay)检测鼻咽癌细胞DNA放射与修复反应的可能性。　方法　采用碱性“彗星”分析法的微胶电泳技术,定量检测评价人高、低分化鼻咽癌细胞系CNE1和CNE2Z细胞在接受X射线照射后,其DNA单链断裂(SingleStrandBreaks,SSBs)的程度,及其与放射剂量的关系和DNA的SSBs在不同检测时间的自身修复情况。　结果　用碱性“彗星”分析法可准确地检测出2Gy单一放射剂量所诱导的两系细胞DNA的SSBs;可见DNA损伤程度在不同照射剂量其结果不同,随剂量递增DNA的损伤加重,与放射剂量呈良好线性相关。15Gy诱导两系细胞的DNA损伤后,10min即可定量检测出受损DNA的确切恢复变化,在照射30min内,其修复较迅速,其损伤程度可降至初时的一半以下,其后修复缓慢,约需持续2h才能复至无照射细胞水平。　结论　“彗星”分析法检测结果能准确反映人鼻咽癌细胞DNA的定量损伤程度及其与放射剂量的关系,以及损伤后自身修复能力在受测时间中的定量变化情况

APPLICATION OF THE COMET ASSAY FOR DETECTION OF RADIATION INDUCED DNA DAMAGE AND REPAIR IN NASOPHARYNGEAL CARCINOMA CELLS

PURPOSE To study the possibility of using the comet assay for detection of radiation induced DNA damage and repair in NPC cells.METHODS Using the alkaline comet assay,a microelectrophoretic technique for detection of visual DNA single strand breaks(SSBs)was used to quantify the DNA SSBs,the correlation between DNA damage and the radiation dose in both of human well and poorly differentiated NPC cell lines(CNE 1 and CNE 2Z)after X ray radiation was given.Also to determine their spontaneous DNA repair of SSB after exposure to x ray. RESULTS The amount of DNA SSBs induced by a 2?Gy radiation single dose was definitely detected in both cell lines.This assay presented the different results of DNA damage induced by different radiation doses;their DNA damage was increased following the increase of the doses;and there was indeed a good linear relationship between the amout of damage detected with this assay and the dose of radiation given to the cells.The repair of 15?Gy radiation induced DNA damage in both of cell line was definitely quantified by detection of the amount of damage at 10 min after exposure to radiation;also the amount of damage was reduced quickly to under half the level of the initial damage within 30?min. Then the repair of DNA damage became slow,and continue for about 2 h to reach the level of unirradiated cells.CONCLUSIONS Using the alkaline comet assay,the fine results of detection can exactly represent the amount of DNA damage induced by radiation in two human NPC cell lines,and the correlation between the amount of DNA damage and the dose of radiation;also the quantitative change for the ability of the spontaneous DNA repair during the period of detetion.