辐射与化疗诱导Egr-1启动子调控GM-CSF基因表达的实验研究

目的 探讨辐照与阿霉素诱导早期生长反应因子(Egr-1)启动子调控造血生长因子基因表达对造血损伤的恢复作用.方法 构建携带Egr-1启动子且下游连接GM-CSF和EGFP基因的真核表达载体(Egr-EG);脂质体介导转染人骨髓基质细胞系HFCL;经60Co γ源辐照2.5 Gy或3μmol/L的阿霉素处理后,采用FACS检测转染细胞绿色荧光蛋白的表达,N-乙酰半胱氨酸(活性氧抑制剂)鉴定辐照及阿霉素处理诱导Egr-1调控下游基因表达的特异性;采用ELISA和RT-PCR检测辐照或阿霉素对HFCL/EG细胞GM-CSF蛋白及mRNA表达的影响;观察辐照及阿霉素处理后的细胞上清对CFU-GM形成的影响.结果 在辐照和阿霉素处理的HFCL/EG细胞中均显示EGFP和GM-CSF表达较未处理组明显增强(t=5.11,P<0.01),未处理组EGFP+细胞占1.2%,阿霉素组EGFP+细胞占15.2%,辐照组EGFP+细胞占18.2%;N-乙酰半胱氨酸明显减少辐照和阿霉素处理后细胞的绿色荧光蛋白表达强度,两组间差异无统计学意义(P0.05);辐照和阿霉素处理组细胞上清促进CFU-GM增殖作用较未处理组明显增强(t=4.37,P<0.01).结论 辐照和阿霉素诱导Egr-1启动子调控的造血生长因子基因表达可能对其所致的造血损伤具有一定的恢复作用.

Egr-1 promoter regulating effect on granulocyte-macrophage colony-stimulating factor (GM-CSF) gene expression induced by doxorubicin and ionizing radiation

Objective To explore the regulating effects of Egr-1 promoter activated by ionizing radiation (IR) and doxorubicin (ADM) on the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) genes. Methods The human GM-CSF cDNA and enhanced green fluorescent protein (EGFP) cDNA were linked together with IRES(internal ribosome entry site) and then inserted into the expression vector pCIneo under control of the Egr-1 promoter(Egr-EG). The vector was transferred into human bone marrow stromal cell line HFCL by liposome transfection. And the cells were exposure to ADM and IR. The activity of EGFP in HFCL/EG cells were detected by FACS. The effect of N-acetylcysteine on the expression of EGFP following exposure to ADM and IR was examined. The amounts of GM-CSF in HFCL/EG after chemotherapy or radiation were measured with ELISA. The effects of GM-CSF in HFCL/EG cultural supernatants on expansion of CFU-GM derived from cord blood were also studied. RT-PCR analysis for the expression of GM-CSF mRNA in HFCL/EG after exposure to ADM or IR. Results The percentage of EGFP+ HFCL/EG cells exposed to ADM and IR was increased compared with non-treatment group (1.2 % and 15.2 % vs 18.2 %, t = 5.11, P < 0.01). The levels of secreted GM-CSF in HFCL/EG cells exposed to ADM and IR was increased (P < 0.01), but no difference between ADM group and IR group (P 0.05). The expression of EGFP by HFCL/EG treated with ADM and IR was significantly decreased by N-acetylcysteine. The effects of GM-CSF in HFCL/EG cultural supernatants on expansion of CFU-GM in ADM group and IR group were significantly higher than that in HFCL group and non-treatment group. However, The CFU-GM count of IR group was higher than that of ADM group. The expression of GM-CSF mRNA in HFCL/EG cells exposed to ADM and IR was significantly increased(t = 4.37, P < 0.01). Conclusions GM-CSF gene expression regulated by Egr-1 promoter induced by ADM and IR could help the recovery from hematopoietic injury.