Selective DNA Delivery to Breast Cancer Cells

Abstract

Abstract : The hypothesis of this research was that specific cell-binding proteins or peptides could be used to enhance (therapeutic) DNA delivery to breast carcinomas. This hypothesis was experimentally tested, with the following results: (1) Recombinant adenovirus type 7 penton base protein (Ad7PB) was shown to mediate DNA transfer into mammalian cells, when coupled to plasm id DNA via a bifunctional peptide linker. However, the efficiency of DNA transfer was poor. (2) Since CD40 is highly expressed on some breast carcinomas, we selected for CD40-binding peptides using phage display technology. When coupled to the surface of adenovirus vectors, these peptides dramatically enhanced virally-mediated gene delivery to CD40-positive murine and human cells. (3) Since alpha v beta 3 integrin is expressed in many breast carcinomas, we generated novel alpha v beta 3-binding proteins by the directed mutagenesis of a natural integrin-binding protein, the tenth fibronectin type III domain (FNfn10). A novel derivative of FNfn10 was identified and shown to bind with high affinity and specificity to purified alpha v beta 3 integrin. It also interacted with cell surface-expressed alpha v beta 3, as determined by flow cytometry, but did not bind detectably to other cell surface integrins. Overall, these experiments have provided important tools and insights that will enhance gene transfer to breast carcinomas.