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[目的]建立食管癌放射抗拒细胞系模型并观察食管癌细胞经射线反复照射后放射敏感性的变化。[方法]60Coγ射线对食管癌EC9706细胞系进行照射,每次2Gy,共照射30次,采用克隆形成实验等测定所得的EC9706R60细胞亚系及其亲代细胞EC9706的放射敏感性,检测细胞周期特征、细胞凋亡率及SP细胞(side population cells)比例。[结果]与亲代EC9706细胞相比,EC9706R60细胞显示出明显放射抗性,其D0、Dq及N值增大,细胞存活曲线肩区增宽,EC9706R60细胞的放射抗性(D0)是EC9706的1.375倍(P<0.05)。EC9706R60细胞S期比例较其EC9706细胞明显增高(32.1%vs.3.8%),G0/G1期比例则明显下降(67.9%vs.96.2%)。食管癌细胞EC9706在经30Gy照射后12h细胞凋亡达到峰值11.17%,经60Gy照射后降低到最低点0.99%。EC9706R60细胞SP细胞的比例较EC9706明显增高。[结论]EC9706R60细胞显示出与亲代细胞不同的细胞周期特征,放射抗拒性与SP细胞的比例存在一定关联。高的放射诱导凋亡率可能意味着放射越敏感,放疗效果越好。
[Objective] To establish a radiosensitive cell line model of esophageal cancer and observe the radiosensitivity changes of esophageal cancer cells after repeated radiation. [Method] 60Coγ-ray was used to irradiate EC9706 cell line of esophageal cancer for 2 Gy each time for 30 times. The radiosensitivity of EC9706R60 cell subline and its parental cell EC9706 was determined by clonogenic assay. The cell cycle characteristics, Rate of apoptosis and ratio of side population cells. [Results] Compared with the parental EC9706 cells, EC9706R60 cells showed significant radioimmunity with increased D0, Dq and N values, broadened shoulder area of cell survival curve, and radiation resistance of EC9706R60 cells (D0) was 1.375 Times (P <0.05). The proportion of S phase of EC9706R60 cells was significantly higher than that of EC9706 cells (32.1% vs.3.8%), while the proportion of G0 / G1 phase was significantly decreased (67.9% vs.96.2%). The apoptosis of esophageal cancer cell EC9706 reached 11.17% at 12h after irradiation with 30Gy, and decreased to 0.99% after 60Gy irradiation. The proportion of SP cells in EC9706R60 cells was significantly higher than that of EC9706 cells. [Conclusion] EC9706R60 cells showed different cell cycle characteristics from their parental cells, and there was a certain relationship between the radioresistance and the proportion of SP cells. A high rate of radiation-induced apoptosis may mean more radiation-sensitive and better radiotherapy.