Relative promoter strengths in four human prostate cancer cell lines evaluated by particle bombardment-mediated gene transfer.

Abstract

The particle bombardment (gene gun) method for gene transfer provides a new and efficient means for transfection of various cell types in culture. In this study we evaluate its application to human prostate tumor cells. Transient expression of the firefly luciferase gene driven by five viral and five cellular promoters was assessed after in vitro gene transfer using the gene gun method. The relative strengths of these promoters were quantitatively determined in four different human prostate tumor cell lines: DU145, PC-3, LNCaP, and CWR22Rv1 cells. In situ histochemical staining of cells, transfected with bacterial beta-galactosidase cDNA as a reporter gene, was also performed to evaluate the transfection efficiency. Time course of gene expression was determined using the luciferase reporter gene. The peak levels of transient expression of firefly luciferase are observed within 24 hr after gene transfer. Sustained but reduced luciferase levels were also detected as long as 5 days post transfection. Up to 35% of bombarded cells in vitro were found to express transgenic beta-galactosidase activity. Among tested viral promoters, cytomegalovirus early enhancer/promoter activity was observed to confer consistently the highest activity in each test cell line, whereas phosphoglycerate kinase gene promoter possessed the highest activity among the cellular promoters tested. The particle bombardment gene-transfer technology can be effectively employed as an efficient method for in vitro gene-transfer into prostate tumor cells. The characterization of relative promoter strength and preference may be useful for future studies of cancer gene therapy approaches.