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目的研究60Coγ射线对DNA碱基切除修复基因hOGG1低表达细胞株放射敏感性的影响。方法以A549细胞和通过稳定转染hOGG1核酶而获得的hOGG1低表达的A549-R细胞为研究对象,用MTT法测定不同剂量γ射线照射后两种细胞的存活率;单细胞凝胶电泳检测60Coγ射线处理后两种细胞DNA损伤与修复的差异;流式细胞术检测照射后两种细胞的周期分布、凋亡率和细胞增殖指数。结果照射后两种细胞的存活率均随照射剂量的增加而下降,但A549-R细胞组的存活率显著低于相同剂量组的A549细胞(P<0·05);所设剂量均可诱导细胞DNA损伤,但DNA迁移长度和彗星细胞率在两种细胞间差异无统计学意义(P>0·05);损伤后的修复在两种细胞间差异有统计学意义(P<0·05),A549-R细胞的修复能力远远低于A549细胞。流式细胞术检测结果表明:照射后两种细胞都表现为G0/G1期细胞阻滞,细胞凋亡随照射剂量的增加而增加,细胞增殖指数随照射剂量的增加而降低,这些变化均以A549-R细胞更为明显。结论hOGG1低表达使得细胞DNA修复能力降低,细胞周期阻滞于G0/G1期、细胞增殖减慢、凋亡增加、存活率下降,从而使细胞对60Coγ射线的放射敏感性增强。
Objective To investigate the effects of 60Coγ-ray on the radiosensitivity of hOGG1 low expression cell line with DNA excision repair gene. Methods A549 cells and A549-R cells with low expression of hOGG1 obtained by stable transfection of hOGG1 ribozyme were used as research objects. The survival rates of the two kinds of cells after γ-ray irradiation were measured by MTT assay. The single cell gel electrophoresis Differences of DNA damage and repair between the two kinds of cells after 60Coγ-ray treatment were observed. The cell cycle distribution, apoptosis rate and cell proliferation index of the two cells were detected by flow cytometry. Results The survival rates of the two kinds of cells decreased with the increase of irradiation dose, but the survival rate of A549-R cells group was significantly lower than that of A549 cells (P <0.05). The dose could be induced Cell DNA damage, but the DNA migration length and the rate of comet cells in the two cells was no significant difference (P> 0.05); repair after injury in the two cells was statistically significant (P <0 · 05 ), A549-R cell repair capacity is much lower than A549 cells. The results of flow cytometry showed that both cells showed G0 / G1 phase cell arrest after irradiation, apoptosis increased with the increase of irradiation dose, and cell proliferation index decreased with the increase of irradiation dose A549-R cells are more obvious. Conclusion The low expression of hOGG1 can reduce the DNA repair ability of cells, arrest the cell cycle in G0 / G1 phase, slow down the cell proliferation, increase the apoptosis and decrease the survival rate, so that the radiosensitivity of the cells to 60Coγ-rays is enhanced.