USE OF TROPISM-MODIFIED ADENOVIRUSES FOR TARGETED DNA DELIVERY TO AIDS-KS CELLS VIA THE FIBROBLAST GROWTH FACTOR-RECEPTOR PATHWAY.

Abstract

Dose-limiting toxicity and chemotherapeutic drug resistance have limited the efficacy of available treatment regimens for acquired immunodeficiency syndrome-associated Kaposi's sarcoma (AIDS-KS). As a result, despite high initial response rates in AIDS-KS patients, all eventually relapse with their disease. Clearly, it is an ideal time for exploration of new and novel therapeutics for AIDS-KS; gene therapy may prove to be a feasible treatment option for this prevalent and debilitating disease. As an initial step in the exploration of a gene therapy approach for AIDS-KS, we have compared the use of lipid- and adenoviral (Ad)-mediated DNA delivery to AIDS-KS cells While both transfection methods were capable of gene transfer to multiple AIDS- and classical KS cell lines, neither appeared to be ideal for this purpose. Cationic lipids consistently gave transfection efficiencies into KS spindle cells of<5%, as measured by β-galactosidase staining. This expression was extremely short-term, peaking at 24 hr and dropping substantially by 48 hr. Adenovirus was more efficient than lipids at delivering DNA to some KS lines, with transfection efficiencies ranging from 20-100%; in these cases, expression levels of the foreign DNA remained high for at least 6 days. Unfortunately, two immortalized KS cell lines KS Y-1 and KS SLK were poorly transducible with adenovirus(1-5%). Thus, these experiments suggested that the Ad receptor is present at variable levels on different AIDS-KS cells and that for optimal and consistently high levels of gene delivery to this cell type, alternative cell surface molecules for viral binding must be identified and exploited. To this end, we have examined the utility of tropism-modified adenoviruses to deliver foreign DNA to AIDS-KS cells. As basic fibroblast growth factor (bFGF) is expressed at high levels in KS spindle cells and is thought to be an important growth and/or angiogenic factor in development of the disease, we have utilized adenoviruses linked via an antifiber monoclonal antibody to bFGF; these viruses are targeted to the bFGF cell surface receptors FGFR1 and FGFR2. Using both the luciferase and green fluorescent protein (GFP) reporter genes, we have been able to demonstrate dramatically increased infectivity of bFGF-Fab-Ad, as compared to Ad with unmodified fiber, for multiple KS cell lines, including KS Y-1. These findings suggest that tropism-modified adenoviruses may be the method of choice for gene delivery to AIDS-KS cells and serve to validate the development of a gene therapy approach for the disease.