ABSTRACT
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.