To evaluate the ability of replication-deficient, recombinant adenovirus vectors to transfer genes to human tumor cells in vivo, adenovirus vectors containing the Escherichia coli lacZ (Ad.RSVβgal) gene (coding for β-galactosidase; used as a cell marker for gene transfer) or the human α1-antitrypsin (Ad-α1AT) cDNA (used as an example of a secreted protein) were administered intraperitoneally to nude mice with human malignant mesothelioma cell (H-MESO-1) malignant ascites. Preliminary in vitro studies showed that both vectors effectively transferred genes to H-MESO-1 cells. Tumor cells recovered from ascites of animals intraperitoneally administered a control adenovirus revealed no evidence of β-galactosidase (β-gal) activity 3 or 14 days later. In contrast, β-gal activity was detected at the same time points in tumor cells from animals receiving intraperitoneal Ad.RSVβgal. Flow cytometric quantification of β-gal activity in recovered cells showed <3% β-gal-positive cells in animals administered control virus, but in animals administered intraperitoneal Ad.RSVβ gal there was a mean of 71 ± 18% positive cells at 3 days and 56 ± 27% at 14 days. Human α1AT was not detected by enzyme-linked immunosorbent assay (ELISA) in ascites of animals receiving a control virus; however, in ascites of animals administered Ad-α1AT, 21,000 ± 3,800 ng/ml of human α1AT was detected at 3 days and 4,900 ± 1,700 ng/ml at 14 days. These data demonstrate that replication-deficient recombinant adenovirus vectors can be used to transfer genes to malignant cells in vivo and suggest a new strategy for genetic modification for antitumor therapy.
Overview summary
In vivo transfer of a gene coding for a therapeutic protein to tumor cells is one strategy that could be used for antitumor gene therapy. The aim of this study was to evaluate adenovirus (Ad) vectors, vehicles that are efficient for gene transfer to a wide variety of cell types, for in vivo gene transfer to malignant cells. Recombinant replication-deficient Ad vectors containing marker genes were used for gene transfer to human malignant cells in vivo in a mouse model. Ad vectors were administered by intraperitoneal injection to nude mice with human mesothelioma cell malignant ascites. Gene transfer could be detected in a high percentage of tumor cells, suggesting that replication-deficient Ad vectors can be used to transfer genes to malignant cells in vivo as a strategy for antitumor gene therapy.
