中文摘要：

目的探讨乏氧诱导因子1α（HIF-101）在辐射诱导人乳腺癌MCF．7细胞自噬性死亡中的作用。方法将人乳腺癌MCF-7细胞分为对照组（常氧组，21％氧气）、照射组（8Gyx射线）、乏氧组（150μmol／LCoCl2）、乏氧加照射组（150μmol／LCoCl2＋8Gy）。150μmol／LCoCl2处理细胞模拟乏氧条件。Westernblot法检测HIF-1α及MAPLC3蛋白表达；MDC及Hoeehst染色方法分别用于检测细胞自噬和凋亡变化情况；克隆形成方法检测细胞辐射敏感性。构建携带人靶向HIF-1α—siRNA的反转录病毒载体，建立MCF-7HIF-1仪Ri沉默细胞模型，将细胞分为对照组（常氧组）、照射组（8Gy）、乏氧组（CoCl：处理）、乏氧加照射组（CoCl2＋8Gy），检测细胞辐射敏感性、自噬及凋亡情况。结果与对照组和照射组相比，HIF-1蛋白在乏氧组和乏氧加照射组表达明显增加，分别为0、0、1．00和1．89。与对照组相比，MAPLC3蛋白在照射组、乏氧组、乏氧加照射组的表达均明显上调，LC3II／LC31比值分别为1．15、1．73、2．38和3．60。细胞辐射敏感性顺次降低，常氧＋三甲基腺嘌呤（3MA）组〉常氧组〉乏氧＋3MA组〉乏氧组。成功构建HIF—let沉默模型（pSUPER-HIF-1仪Ri）与空载体对照模型（pSUPER），并检测了2种细胞的辐射敏感性。与常氧组相比，乏氧组MCF-7-pSUPER细胞存活分数显著增加（t=3．080、6．946、6．658、6．380，P〈0．05），辐射敏感性降低。而MCF-7-pSUPER—HIF-1αRi细胞，常氧与乏氧条件下细胞存活分数无明显改变。不同处理组（照射组、乏氧组和乏氧加照射组）的MCF-7-pSUPER-HIF-1aRi细胞与MCF-7-pSUPER细胞相比较，自噬百分率分别降低21．1％、25．5％和15．5％（t=-4．635、-4．738、-6．354，P〈0．05），但凋亡百分率差异无统计学意义。结论在人乳腺癌MCF-7细胞中HIF-1α可增加辐射诱导的自噬，同时降低辐射敏感性，对细胞凋?

英文摘要：

Objective To study the effects of hypoxia-inducible factor-let （HIF-lct） on radiation- induced autophagic cell death in breast cancer cells. Methods MCF-7 cells were divided into four groups ： control （ normoxia, 21% Oxygen） , irradiation （8 Gy X-rays） , hypoxia （ Cobalt chloride, CoCl2 ） and irradiation with hypoxia （ CoC12 ）. 150 μmoL/L CoC12 was utilized to induce hypoxic conditions. Western blot was applied to detect the expression of HIF-1α and MAPLC3. MDC and Hoechst staining were used to detect autophagy and apoptosis. Radiosensitivity was detected by cloning formation. The short hairpin interfering RNA （shRNA） retroviral transduction particles targeting HIF-1α was transfeeted into MCF-7 cells to establish HIF-1α knockdown cells, then the radiosensibility, autophagy and apoptosis were detected. Results Compared with control group and irradiation group, the protein level of HIF-1 increased obviously in the normaxia, irradiation, hypoxia and irradiation with hypoxia groups, and the values were 0, 0,1.00,1.89, respectively. The expression levels of MAPLC3 were markedly up-regulated in irradiation, hypoxia and irradiation with hypoxia groups as compared with control, and the ratios of LC3II/LC3I were1.15, 1.73, 2.38 and 3.60, respectively. The radiosensitivity of MCF-7 cells decreased in the following order： normoxia with 3MA 〉 normoxia 〉 hypoxia with 3MA 〉 hypoxia. HIF-1α knockdown cell （pSUPER-HIF-1αRi） and vector control were constructed. After treatment with COC12, survival fraction of MCF-7-pSUPER was significantly higher than that of control （ t = 3. 080, 6. 946, 6. 658, 6. 380, P 〈 0. 05） , and radiosensitivity was down-regulated after irradiation, but there was no significant difference between normoxia and hypoxia in survival fraction of MCF-7-pSUPER-HIF-1α Ri. After treatment of irradiation or hypoxia, the autophagic fractions in MCF-7-pSUPER-HIF-1α Ri significantly decreased, reduced by 21.1% , 25.5% , 15.5% , respectively（ t = 4. 635,4. 738, 6.