2Gy多分割不同顺序照射对鼻咽癌CNE-2细胞生物效应的研究

目的探讨总剂量为2 Gy时部分分割和顺序照射对鼻咽癌CNE-2细胞的杀伤效应的差异。方法采用克隆形成法和四唑盐（MTT）比色法,检测2 Gy剂量照射后鼻咽癌CNE-2细胞的细胞生存率和具有代谢活性细胞比例。结果在多个等分割照射中,较小分割（≤0.5 Gy）多次照射的细胞存活率均明显低于单次照射组（2 Gy）,差异有统计学意义（P〈0.05）,而较大分割（1 Gy）照射与单次照射组细胞生存率差异无统计学意义;在2个部分分割和3个部分分割照射中,随着S分割剂量的增大,各S-L和S-S-L照射组细胞生存率呈逐渐下降趋势,至S分割为0.4 Gy（S-L）或者0.5Gy（S-S-L）组时细胞生存率最低;大部分S-L照射组细胞生存率明显低于L-S照射组,大部分S-S-L照射组细胞生存率和相对细胞生存率明显低于L-S-S照射组,差异有统计学意义（P〈0.05）。结论总剂量为2 Gy照射时,分割剂量大小和照射顺序是影响鼻咽癌CNE-2细胞放射治疗生物效应的重要因素。

Study on the Biological Effect of Nasopharyngeal Carcinoma CNE-2 Cells Exposed with the the Dose of 2Gy in Various Partial Fraction Dose Sequences

Objective To Study the biological effects of nasopharyngeal carcinoma CNE-2 cells exposed with the dose of 2 Gy in various partial fraction（PF） dose sequences. Methods Cell survival and proliferation were determined by clonogenic assay and 3- （4,5-dimethylthiazol-2 -yl） -2,5 diphenyltetrazolium bromide （MTY）. Results In a number of equal fractionations, the survival fraction in the group of S-dose （0.5 Gy,0.4 Gy,0.2 Gy） was significantly lower than that of the single irradiation （2 Gy）, the difference was significant （P 〈 0.05）. There was no significant difference between the survival fraction in the group of L-dose （1 Gy） and single irradiation （2 Gy） （P 〉 0.05 ）. Significant differences in the biologic effects were observed between sequences in which the L-dose was given before or after the S-doses in both the MTr and clonogenic assay ：with the increase of Sdose,the survival fraction of S-S-L and S-L schemes declined gradually by clongenic assays. The smallest cell survival was seen when the S-dose was 0.4 Gy（S-L） or 0.5 Gy（S-S-L）. Nearly all the S-L and S-S-L schemes produced greater cytotoxic effects than the L-S and L-S-S schemes, the difference was significant （P 〈 0.05）. Conclusion The biological effects of 2 Gy may dif- fer in different settings depending on the size and sequence of the partial fractions for nasopharyngeal carcinoma cell line CNE-2.