中文摘要：

目的：观察体外低氧和常氧培养条件下喉癌Hep-2细胞系在放疗前后CD133＋细胞比例及生长抑制率的变化,探讨肿瘤干细胞在低氧介导的喉癌放疗抵抗中的作用。方法：体外常氧和低氧环境下培养人喉癌Hep-2细胞,用western blot检测HIF-1α的表达。细胞汇合约80%左右时后分别给予0、5、10、15、20Gy的60 Co照射,检测各组细胞放疗后不同时间细胞生长抑制率和CD133＋细胞比例的变化。结果：低氧和常氧条件下,Hep-2细胞放疗后24h细胞增殖抑制率达到高峰,并随放疗剂量的增加而增加。常氧组各个剂量和时间点的生长抑制率均高于低氧组,24h、10Gy时差异最大,有统计学意义（P〈0.05）。放疗后CD133＋细胞低氧和常氧组均有不同程度的富集,低氧组在各个剂量和时间点的CD133＋细胞比例均高于常氧组,24h、10Gy时差异最大,有统计学意义（P〈0.05）。结论：喉癌干细胞在低氧介导的喉癌放疗抵抗中有重要作用,并提示阻断低氧因素可能会增强喉癌的放疗敏感性。

英文摘要：

Objective： To study whether cancer stem cells promotes resistance of laryngeal squamous cancer to irradiation mediated by hypoxia. Method： Hep-2 cells were respectively cultured in hypoxia and normoxia enviroment,and the express of HIF-1α was detected by western blot.Then they were radiated with different doses of γ-rays.After that we detected growth inhibition ratio with MTT assay,cell circle and ratio of CD133＋ cells with Flow cytometry at defferent times. Result： MTT assay showed that inhibition ratio of the hypoxia group was lower than that of the normoxia group after different doses of γ-rays at each time point,and the difference was significant 24 h after 10 Gy irradiation（P0.05）.The results of Flow cytometry demonstated that cells of the two groups were arrested at G1 phase,and cells ratio in G1 phase of the hypoxia group was higher than that of he normoxia group after 10 Gy irradiation.The ratio of CD133-positive cells was higher in the hypoxia group than in the normoxia group after radiation,and difference was significant 24 h after 10 Gy irradiation（P0.05）.In each group,the ratio of CD133-positive cells became higher after radiation than that before radiation（P0.05）. Conclusion： We can conclude that cancer stem cells play an important role in radioresistance mediated by hypoxia.