γ射线照射后乏氧诱导因子1α对肝癌细胞存活的影响

Study on radiation regulation of hypoxia inducible factor-1α expression and its correlation with hepatoma radiosenscitivity

目的研究辐射对肝癌细胞内乏氧诱导因子1α（HIF-1α）的调节作用以及HIF-1α的变化对肝癌细胞存活的影响。方法采用CoCl2化学模拟乏氧预处理人肝癌HepG2细胞，经不同剂量的γ射线照射后，通过细胞集落形成实验，比较有氧及化学模拟乏氧条件下细胞存活水平的差异。同时采用RT-PCR和Western blot方法检测照射后细胞内HIF-1α在转录和翻译水平上的变化。结果在化学模拟乏氧条件下，细胞存活分数（SF）显著增加，与有氧对照组比较差异有统计学意义，且两种不同作用条件下的SF比值（SFco／SFo2）随照射剂量逐渐增加，同时，经照射后细胞内的HIF-1α表达升高，并呈剂量依赖模式，HIF-1α的表达与照射后的细胞存活水平具有较强的关联性。结论辐射可诱导肝癌细胞内HIF-1α的表达升高，HIF-1α的表达变化可能影响细胞的存活水平。

Objective To study the regulation of hypoxia inducible factor-1α（HIF-1α） expression in hepatoma cells after irradiation and the expression of HIF-1α effect on the radiosensitivity of heptoma cells. Methods HepG2 cells were pretreated by Cobalt chloride （COCl2）, a chemical hypoxia agent, to induce and stabilize the expression of HIF-1α, and then exposed to different γ-irradiation doses. Clonogenic assay was used to evaluate HepG2 cell survival fraction （SF） after irradiation under normoxia and chemical hypoxia. Reverse transcriptase polymerase chain reaction （RT-PCR） and immunoblot assay （Western blot） were utilized to detect the changes of intracellular HIF-1α on the level of transcripation and translation, Results Cell survival level was elevated by chemical hypoxia and there was a statistical difference between chemical hypoxic group and normoxic group. The ratios of SF（ SFco/SFo2 ）on two different conditions were increased with irradiation doses. Meanwhile, the irradiation induced up-regulation of HIF-1α in dose-dependent manner. The expression of HIF-1α was correlated with HepG2 cell survival level to some extent. Conclusions Irradiation could up-regulate the level of HIF-1α expression in HepG2 cells under chemical hypoxic condition. The cells survival level might be influenced by the changes in HIF-1α expression.