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目的比较低剂量超微分割放疗与常规分割放疗对脑胶质瘤细胞的作用效果。方法以低剂量率超微分割放疗(每0.2 Gy间隔3 min,剂量率为0.066 7 Gy/min)和常规分割(剂量率4～6 Gy/min)2种方法照射脑胶质瘤GL261细胞,分别在第1、2、3天采用彗星分析和流式细胞分析检测细胞DNA损伤、凋亡、细胞周期分布。结果彗星实验显示低剂量率超微分割放疗可产生与常规分割等效的细胞DNA损伤,2组间各时间点彗星荧光图像的尾部DNA百分含量(tail DNA%)、尾长(tail length)、尾距(tail moment)均数差异无显著性(P>0.05)。细胞凋亡、存活情况显示超微分割组各时间点的细胞存活率较常规分割组低,差异有显著性(P<0.01),2组细胞周期分布差异无显著性(P>0.05)。结论低剂量率超微分割放疗对脑胶质瘤细胞GL261可产生与常规分割等效的DNA损伤,但对细胞的杀伤作用强于常规分割照射。该现象可能与低剂量率超微分割照射胶质瘤细胞后有不同的DNA损伤修复机制有关。
Objective To compare the effect of low-dose ultrafractionated radiotherapy and conventional radiotherapy on glioma cells. Methods Gl gluloma GL261 cells were irradiated by two methods of low dose rate ultrafractionation radiotherapy (3 min every 0.2 Gy dose rate and 0.066 7 Gy / min dose rate) and conventional fractionation (dose rate 4 ~ 6 Gy / min) The DNA damage, apoptosis and cell cycle distribution were detected by comet assay and flow cytometry on days 1, 2 and 3, respectively. Results The comet assay showed that low dose rate ultrafractionated radiotherapy can produce DNA damage equivalent to conventional segmentation, tail DNA% and tail length of comet fluorescence images at different time points in the two groups, There was no significant difference in tail moment mean (P> 0.05). Cell apoptosis and survival showed that the cell survival rate in the subdivision group was significantly lower than that in the conventional subdivision group (P <0.01). There was no significant difference in the cell cycle distribution between the two groups (P> 0.05). Conclusion Low-dose rate ultrafractionated radiotherapy can produce equivalent DNA damage to glioma cells GL261, but its killing effect on cells is stronger than that of conventional radiotherapy. This phenomenon may be related to the mechanism of DNA damage repair after glioma cells are irradiated by ultra-microdissection of low dose rate.