The Expression of GFP Gene in Transformed and Tumor Cells

Objective To search the appropriate experimental conditions for using green fluorescent protein (GFP) as a reporter gene in tumor gene therapy. Methods The plasmids carrying mutated GFP gene were transfected into the eukaryotic cells to observe transient gene expression. These studies were conducted to 1. directly determine GFP expression and express stability in the COS-7 cells, 2. compare the transfection efficiency of two plasmids pcDNA 3-EGFP, pSVK 3-S65T with different promoters in different tumor cell lines, 3. determine two genes expression in a single cell using LacZ cotransfected with GFP by FACS. Results Fluorescence could be detected in intact viable cells under different sets of conditions. The expression of GFP might last two weeks or more and the expressed fluorescence was stable. The transfection rate of pcDNA 3-EGFP expressed was different in three tumor cell lines examined. But pSVK 3-GFP expressed similarly in four tumor cell lines examined. FACS showed the probability of two genes entering a single cell is above 85% at the ratio 1∶4. Conclusion The above data indicate that the GFP can be visualized continuously and directly for gene expression in living cells. GFP may also be used for quicklly selecting cells carrying a target gene.