The development of gene therapy has allowed the potential treatment and prevention of many genetic diseases to become a reality. Lung cancer is a disease that can potentially be treated by gene therapy, as present day therapeutics have little effect. A key to the successful use of gene therapy is the development of efficient nucleic acid delivery systems. The goal of this project is to develop a non-viral, DNA/protein complex that utilizes a lung cancer cell specific ligand for the selective delivery of ionically attached nucleic acids. Initially, epidermal growth factor (EGF) will be used as the targeting ligand and will be modified by one of several different chemical reactions, to attach the polycation, poly- L-lysine (PLL) to the ligand. This EGF/PLL conjugate will then be tested for the ability to bind DNA, a polyanion. Once optimum conditions are achieved for DNA binding, the complexes will be tested for the ability to deliver genes into cells both in vitro and in vivo. Since the EGF/DNA complex is internalized by a receptor-mediated pathway, various endosomal lysis agents will be used to by-pass the normal degradation that occurs in this pathway. In the event that EGF cannot be used, other ligands will be tested such as transferrin or monoclonal antibodies specific for lung cancer cell receptors. Two tumor cell lines, which express either high or low levels of the EGF receptor, will be used in the analysis in vitro. The DNA/protein complexes will also be administered and tested in vivo by injection through one of several routes to lung tumors that have been generated in nude mice. Since a large majority of lung tumors are deficient in the expression of the tumor suppressor p53, a plasmid that expresses p53 will be delivered into the lung tumor cells and tested for the ability to promote cancer cell death. The p53 gene will also be cloned into a plasmid that replicates episomally to ensure that the plasmid will exist in the cancer cell for the life of the cell.
