HIF-1α基因表达沉默对肝癌细胞的放射增敏作用

目的：探讨在乏氧条件下，HIF—1α在肝癌细胞中的表达，及HIF—1α表达沉默后对肝癌细胞的放射增敏作用。方法：利用Western bolt方法检测不同乏氧时相HIF—1α在肝癌细胞Hep3b中的表达。构建特异性的HIF—1α慢病毒干扰载体，利用慢病毒感染肝癌细胞Hep3b，杀稻瘟菌素进行药物筛选，利用RT—PCR和Western blot检测干扰效果。利用克隆形成实验观察HIF—1α表达沉默后对肝癌细胞反射敏感性的影响。结果：在乏氧条件下，肝癌Hep3b细胞HIF-1α蛋白表达增强。利用特异性的HIF-1α慢病毒沉默肝癌细胞HIF-1α的表达，Hep3b细胞中HIF—1α表达降低了90％，说明HIF—1α载体构建成功。HIF—1α表达沉默后，能明显降低放射后Hep3b细胞的克隆形成率，其放射增敏比为2．18。结论：乏氧可以诱导肝癌细胞HIF-1α的表达，HIF-1α表达沉默对肝癌细胞具有放射增敏作用。

缺氧诱导因子1α(HIF1α)下调HepG2细胞中甘氨酸-N-甲基转移酶(GNMT)基因的表达

目的 探讨乏氧对甘氨酸-N-甲基转移酶（Glycine-N- methyltransferase,GNMT）表达的影响,以及GNMT与缺氧诱导因子1α （hypoxia inducible factor 1 alpha,HIF1α）表达之间的关系。方法 HepG2,293T,H460 3株细胞常规培养并设立常氧组和乏氧组,待细胞生长至50%~60%融合后,将乏氧组细胞放入1%氧气乏氧箱继续培养24 h,常氧组继续常规培养24 h后,运用半定量PCR,实时荧光定量PCR方法分析HepG2,293T,H460 3株细胞乏氧后相对于常氧GNMT基因的表达变化;通过小RNA干扰方法敲低HepG2细胞中HIF1α基因和HIF2A基因,运用实时荧光定量技术检测干扰效率,并检测GNMT基因的表达变化。结果 乏氧能够下调HepG2,293T,H460 3株细胞中GNMT基因的表达,HepG2细胞中抑制最明显;3株细胞的GNMT基因表达抑制率分别为68%,17%,21%;在HepG2细胞中敲低HIF1α基因能够引起GNMT表达明显上调,而敲低HIF2A后GNMT表达无明显变化。结论 在HepG2细胞中乏氧可能通过HIF1α下调GNMT的表达。

ROS-mediated regulation of CXCR4 in cancer

Oxidative stress and the accumulation of reactive oxygen specie （ROS） play a role in cancer cells developing an advanced, phenotypic signature that associates with metastasis and progression. Increased ROS concentrations are involved in promoting cancer development and metastasis by inducing expression of oncogenes, suppressing activity of anti-survival molecules and by activating various cell survival and proliferation signaling pathways. Oxidative stress is higher in the epithelium of cancer patients than patients without the disease, and antioxidant trials are currently being explored as a therapeutic option. However, studies have shown that ROS increases expression of CXCR4 in cancer and immune cells. CXCR4 expression in tumors strongly correlates to metastasis and poor prognosis. Herein, we discuss an emerging relationship between ROS and CXCR4 in cancer cells.