Folate -targeted gene delivery to cancers
Abstract
The folate receptor is overexpressed in cancer cells and has been used for delivery of various agents. We have investigated the expression of folate receptor on hematopoietic cells and have found that CD34+ cells express both its β and γ isoforms but does not transport folic acid. Therefore gene therapy of cancer exclusively through the folate receptor should not harm stem cell function. In our efforts to produce a targeted viral vector we first demonstrated that direct conjugation of folic acid to a virus did not enable folate receptor mediated viral gene expression. We then developed non-viral folate-targeted transfection complexes containing a caged pH-sensitive lipid, N-citraconyl-dioleyl phosphatidylethanolamine, for pH-dependent release of endosome-entrapped DNA into the cytoplasm. We also optimized the amount of targeting ligand folate-polyethyleneglycol-dioleyl phosphatidylethanolamine for folate receptor specific transfections. These liposomal vector when prepared with an optimally compacted DNA core, displayed greatly improved transfection efficiencies. When liposomal vectors are prepared with a serum stable, cationic lipid formulation, folate receptor dependent transfections were contingent to specific concentrations of the targeting lipid. These vectors were then tested in mice for gene expression in a folate receptor positive M109 tumor model. Finally, since the levels of targeted gene expression would be proportional to the number of receptors on the cell surface and the rate of receptor recycling, we also studied the effect of folate receptor recycling on folic acid conjugated ligands of various sizes and composition.
Degree
Ph.D.
Advisors
Low, Purdue University.
Subject Area
Biochemistry|Oncology|Molecular biology
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