Cell type-specific gene expression, mediated by TFL-3, a cationic liposomal vector, is controlled by a post-transcription process of delivered plasmid DNA

Abstract

The issue of whether the TFL-3, a recently developed cationic liposome, achieves efficient gene expression in different mammalian cell lines (NIH/3T3, LLC, A431 and HeLa cells) was examined. The issue of whether gene expression is related to the amount of plasmid DNA (pDNA) delivered in cells or nuclei following transfection was also examined. The cells were transfected for 1 h with pDNA/TFL-3 lipoplexes, and the transfection efficiency was determined by means of a luciferase activity assay. The amount of intracellular and intranuclear pDNA following the transfection was also quantitatively determined. Successful transgene expressions in all cell lines we tested were observed under our experimental conditions, suggesting that the TFL-3 represents a suitable nonviral vector system for the successful gene expression in mammalian cells in vitro. The degree and rate of gene expression were dependent on the type of cells used as well as the incubation time after transfection, but these parameters were independent of the amount of gene delivered to cells and nuclei. These results suggest that TFL-3 mediated gene expression is largely controlled by the process of post-transcription of the delivered pDNA, and not by the process of cellular entry of pDNA and cytoplasmic trafficking of pDNA into nuclei, which is dependent on the cell type. Therefore, the results obtained here clearly suggest that the cell type-specific improvement in transcription efficiency of pDNA and translation of the derived mRNA, together with an improved delivery system to enhance the nuclear delivery of pDNA, is necessary to achieve efficient transgene expression in mammalian cells.