目的： 观察三氧化二砷（As 2O 3）在低氧条件下对食管癌Eca109细胞增殖、细胞周期及凋亡的影响，探讨其发挥放射增敏作用的可能机制。 方法： CoCl 2处理模拟肿瘤细胞模拟低氧微环境，MTT法分别检测常氧和低氧条件下不同浓度As2O3及不同剂量放射线对食管癌Eca109细胞增殖的抑制作用，流式细胞术检测低氧下As 2O 3、放射线单独及两者联合对细胞周期及凋亡的影响，Western blotting检测经As 2O 3、放射线单独及两者联合作用后Eca109细胞中HIF-1α、p27蛋白的表达情况。 结果： 在常氧和低氧两种条件下，As2O3均呈时间和剂量依赖方式抑制Eca109细胞增殖，相同时间和相同剂量条件下，其抑制水平相当（P>0.05）；而低氧下放射线对Eca109细胞增殖的抑制作用较常氧下明显减弱（P<0.05）。低氧下Eca109细胞周期出现G 0/G 1期阻滞、G 2/M期细胞比例明显减少（P<0.05），As 2O 3在低氧条件下可诱导G 2/M期阻滞、G 0/G 1期细胞比例减少。As 2O 3与放射线联合作用时，Eca109细胞的凋亡率大于两者单独作用之和。低氧条件下，Eca109细胞HIF-1α、p27蛋白表达均明显增强，As 2O 3可逆转HIF-1α、p27表达水平的升高。 结论： 低氧条件下，As 2O 3对食管癌Eca109细胞有放射增敏作用，其机制可能与下调HIF-1α进而降低p27表达水平、解除G 0/G 1期细胞周期阻滞和促进细胞凋亡有关。

Objective : To investigate the effect of arsenic trioxide (As2O3) on proliferation, cycle progression, apoptosis and radio-sensitivity of esophageal carcinoma cells under hypoxia. Methods: Human esophageal carcinoma Eca109 cells were treated with different concentrations of As2O3 or doses of radiation under a hypoxic condition mimicked cobalt chloride (CoCl2). At different time points after treatment, cell viability was determined by MTT assay, cell cycle progression and apoptosis by flow cytometry (FCM), and expression of HIF-1α and p27 at the protein level by Western blotting. Results: In time- and dose-dependent manners, As2O3 inhibited Eca109 cell proliferation similarly under both normoxic and hypoxic conditions (P>0.05). However, radiation-mediated inhibition of Eca109 cell proliferation was significantly less strong under hypoxia than under normoxia (P<0.05). Compared with normoxia, hypoxia increased cell cycle arrest at the G0/G1 phase and decreased the proportion of cells at the G2/M phase (P<0.05). As2O3 induced cell cycle arrest at the G2/M phase and reduced the proportion of cells at the G0/G1 phase under hypoxia. The combination of As2O3 and irradiation resulted in more significant apoptosis in Eca109 cells as compared with the use of As2O3 and irradiation each alone (P<0.05). Under hypoxia, HIF-1α and p27 protein contents were significantly increased as compared with normoxia (P<0.05), but the increase was significantly attenuated by As2O3 (P<0.05). Conclusions: Under hypoxia, As2O3 may increase the sensitivity esophageal carcinoma cells to radiation, possibly through down-regulating the expression of HIF-1α and its down-stream target p27, thus releasing G0/G1 phase arrest and inducing G2/M phase arrest.

高等院校博士学科点专项科研基金资助(No.20091323110011)。