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[目的]建立放射抗拒人鼻咽癌细胞系模型并观察人鼻咽癌细胞经X射线反复照射后放射敏感性的变化及初步探讨其放射抗拒的机制。[方法]利用X射线对人鼻咽癌细胞HONE-1、SUNE2细胞系进行照射,采用剂量梯度法确定其亚致死照射剂量后,每次照射1次亚致死剂量,共照射5次或以上(HONE-1:6Gy×5次,SUNE2:4Gy×7次)。采用克隆形成实验等测定所得的HONE-1-IR、SUNE2-IR细胞系及其亲代细胞HONE-1、SUNE2的放射敏感性、细胞周期特征及SP细胞比例。[结果]与亲代细胞HONE-1、SUNE2相比,HONE-1-IR、SUNE2-IR细胞的D0、Dq及SF2值均增大,HONE-1-IR细胞的放射抗拒性(D0)是HONE-1细胞的1.336倍,SUNE2-IR的D0值为SUNE2的1.094倍,表现出一定的放射抗拒性;HONE-1-IR、SUNE2-IR的S期细胞比例较其亲代细胞HONE-1、SUNE2明显增高(HONE-1-IRvsHONE-1:43.56%vs23.08%,P=0.002;SUNE2-IRvsSUNE2:32.64%vs19.20%,P=0.029),G2/M期细胞比例明显降低(HONE-1-IRvsHONE-1:13.65%vs29.51%,P=0.002;SUNE2-IRvsSUNE2:10.25%vs22.63%,P=0.026),而G0/G1期细胞比例则无明显差异(P=0.735,P=0.572);HONE-1-IR细胞的SP细胞比例较HONE-1细胞明显增高(3.96%vs0.02%),而SUNE2-IR细胞与SUNE2细胞的SP细胞比例分别为0.27%、0.06%。[结论]人鼻咽癌细胞株HONE-1、SUNE2经亚致死剂量X射线多次照射后而建立的后代细胞HONE-1-IR、SUNE2-IR具有一定的放射抗拒性;HONE-1-IR、SUNE2-IR细胞显示出与亲代细胞不同的细胞周期特征,放射抗拒性也可能与SP细胞比例增高有关,值得进一步探讨。
[Objective] To establish a radiosensitive human nasopharyngeal carcinoma cell line model and observe the change of radiosensitivity of human nasopharyngeal carcinoma cells after repeatedly irradiated by X-rays and to explore the mechanism of its radioresistance. [Method] The human nasopharyngeal carcinoma cell lines HONE-1 and SUNE2 were irradiated by X-ray. After the sublethal dose was determined by the dose gradient method, the sub-lethal dose was irradiated once per irradiation for 5 times or more HONE-1: 6 Gy × 5 times, SUNE2: 4Gy × 7 times). Radiation sensitivity, cell cycle characteristics and SP cell ratio of HONE-1-IR and SUNE2-IR cell lines and their parental cells HONE-1 and SUNE2 were determined by clonogenic assay. [Result] The D0, Dq and SF2 values of HONE-1-IR and SUNE2-IR cells were all higher than those of parental cells HONE-1 and SUNE2. The radioresistance (D0) of HONE- -1 cells, SUNE2-IR D0 value is 1.094 times that of SUNE2, showing some radioresistance. The proportion of S phase cells of HONE-1-IR and SUNE2-IR cells was higher than that of their parental cells HONE-1 and SUNE2 (HONE-1-IRvsHONE-1: 43.56% vs23.08%, P = 0.002; SUNE2-IRvsSUNE2: 32.64% vs19.20%, P = 0.029) -IRvsHONE-1: 13.65% vs29.51%, P = 0.002; SUNE2-IRvsSUNE2: 10.25% vs22.63%, P = 0.026). There was no significant difference in the proportion of cells in G0 / 0.572). The proportion of SP cells in HONE-1-IR cells was significantly higher than that in HONE-1 cells (3.96% vs 0.02%), while the percentage of SP cells in SUNE2-IR cells and SUNE2 cells were 0.27% and 0.06%, respectively. [Conclusion] HONE-1 and SUNE2-IR of the progeny cells of human nasopharyngeal carcinoma cell line HONE-1 and SUNE2 after being irradiated by sublethal dose of X-rays for several times have certain radioresistance; HONE-1-IR , SUNE2-IR cells showed different cell cycle characteristics than the parental cells, and the radioresistance may also be related to the increased proportion of SP cells, which is worth further study.