人结肠癌放射抗拒性细胞株的建立

目的应用连续照射的方法建立人结肠癌放射抗拒细胞株SW480-R，为研究人结肠癌放射抗拒的机制提供模型。方法用2Gv剂量的x射线照射人结肠癌SW480细胞株，每天1次，每周5d，分别照射不同周期后，按照细胞存活率筛选出放射抗拒细胞株SW480．R，并检测细胞的倍增时间。以细胞克隆形成实验检测细胞的放射敏感性，MTT法检测照射后不同时间点的细胞存活分数，流式细胞仪检测细胞的细胞周期分布，并分别与亲代结肠癌细胞株进行比较。结果经2Gy照射3周后细胞仍有存活，可作为放射抗拒细胞株的模型。SW480．R细胞株的倍增时间明显长于亲代SW480细胞株（脚．05），SW480-R细胞株的放射抗拒l生增加，照射后12h的细胞存活率较SW480细胞株显著增高（98．40％US92．81％，P〈0．001）。流式细胞仪检测细胞周期显示，SW480一R细胞株的细胞周期分布与SW480细胞株不同，G2／M期明显增高。结论人结肠癌细胞株SW480每天经x射线照射2Gy，连续照射3周后可以得到具有放射抗拒细胞株SW480．R。此细胞株具有稳定的放射抗拒性，且与亲代细胞株有不同的细胞周期分布。

Establishment of a radioresistant human colon cancer line

Objective To establish the radioresistant human colon cancer cell line SW480-R,which could serve as a reference line for mechanistic studies of radioresistance. Methods Human colon SW480 cancer cells were repeatedly exposed to X-rays （2 Gy per fraction）.After exposing the ceils for different periods, the novel radioresistant subline SW480-R was obtained.The doubling time of SW480 and SW480-R cells was determined by MTT assay, and relative radiosensitivity by standard colony formation assay.Survival rates after irradiation were measured by MTT assay. The distribution of cells in different stages of the cell cycle was investigated by flow cytometry before and after irradiation. Results Carcinoma cells survived after being exposed to 2 Gy for 3 weeks, and these cells were considered to be a radioresistant subline of SW480 cells.The resistant SW480-R cells showed greater radioresistance and longer doubling time than the parental SW480 cells（33.93 vs 24.87 h,P〈0.05）.The resistant cells showed a higher survival rate after irradia- tion than did SW480 cells（98.40 vs 92.81%,P〈0.001 ）,and a higher percentage of cells in G2/M phase. Conclusion The new subline SW480-R is more radioresistant than the parental SW480 cell line, and it has a different cell cycle distribution.