非小细胞肺癌EGFR基因突变与放射敏感性的相关性

Correlation study between EGFR gene mutation and radiosensitivity in non-small cell lung cancer

目的探讨表皮生长因子受体(EGFR)基因突变与非小细胞肺癌(NSCLC)放射敏感性的相关性及可能机制。方法选取EGFR基因突变的NSCLC细胞株PC-9、H1975和EGFR野生型NSCLC细胞株A549。克隆成型实验检测放射敏感性,流式细胞术检测细胞凋亡和细胞周期,Western blot检测凋亡蛋白和修复蛋白表达。结果 PC-9、H1975细胞放射敏感性明显高于A549细胞,4 Gy照射下克隆存活率分别为10.0%、5.5%和44.3%;4 Gy照射后48 h PC-9和H1975细胞凋亡率显著高于A549细胞,分别为18.300%、17.533%和11.733%。A549细胞发生G_0/G_1期阻滞显著高于PC-9、H1975细胞,4 Gy照射后48 h G_0/G_1期细胞分别为74.480%、70.293%和57.016%。A549细胞在4 Gy照射后促凋亡蛋白Bax表达缺失,凋亡蛋白Caspase-3、抗凋亡蛋白Bcl-2、修复蛋白DNA-PKcs在24 h仍有表达。而PC-9、H1975细胞在4 Gy照射后Bax、Caspase-3表达增多,Bcl-2不表达,DNA-PKcs表达减少。结论 EGFR 19外显子缺失突变细胞PC-9和21外显子点突变细胞H1975,相对EGFR野生型细胞A549对放射线敏感,其机制与细胞周期G_0/G_1期阻滞、Bax表达增多、DNAPKcs、Bcl-2表达降低有关。

Objective To investigate the correlation between the epidermal growth factor receptor （EGFR） gene mutations and radiosensitivity of non - small cell lung cancer （NSCLC） and the possible mechanism. Methods EGFR - mutant NSCLC cell lines PC -9 and H1975, and wild- type EGFR NSCLC cell line A549 were selected. The clonogenic cell survival assay was applied to determine the radiosensitivity, flow cytometry was applied to detect cell apoptosis and cell cycles distribution, and Western blot assay was applied to detect the expression of apoptotic and repair proteins. Re- sults The radiosensitivities of both PC - 9 and H1975 cells were significantly higher than that of A549 cells, and the clo- nogenic survivals after 4 Gy radiation were 10. 0% , 5.5% and 44. 3% , respectively. The apoptosis rates of PC - 9 and H1975 cells at 48 h after 4 Gy radiation were significantly higher than that of A549 cells, which stood at 18. 300% , 17. 533% and 11. 733%, respectively. The incidence of G0/G1 phase arrest in A549 cells was significantly higher than those in PC -9 and H1975 cells, and the Go/G1 phase rates at 48 h after 4 Gy radiation were 74. 480%, 70. 293% and 57. 016%, respectively. After 4 Gy radiation, there was no expression of pro - apoptotic protein Bax in A549 cells, whereas there was still expression of the apoptotic protein Caspase - 3, the anti - apoptotic protein Bel - 2 and the repair protein DNA -PKcs at 24 h. However, after 4 Gy radiation, the expression of Bax and Caspase -3 in PC -9 and H1975 cells were increased, with no expression of Bcl - 2 and down - regulation of DNA - PKcs. Conclusion PC - 9 cells with EGFR 19 exon deletion mutation and H1975 cells with exon 21 point mutation are more sensitive to radiation, as compared with the wild - type EGFR A549 cells. The possible mechanism is associated with G0/G1 phase arrest of cell cycles, in- creased Bax expression, and decreased expressions of DNA -PKes and Bcl -2.