Activated tyrosine kinase c-Src-responsive artificial gene carrier: in vitro and in vivo evaluation

The proto-oncogene c-Src is a protein-tyrosine kinase that is associated with increased risk of acute and chronic kidney diseases, cardiovascular diseases, neurological diseases, and cancers. The purpose of this study was to develop a gene delivery carrier responding to activated c-Src and to evaluate its efficacy in vitro and in vivo. The polymeric gene carrier consists of a neutral main chain bearing a peptide substrate of c-Src or negative control peptide. Complexes of the polymer containing c-Src-targeting peptides and DNA were phosphorylated in the presence of c-Src, resulting in release of the DNA. Green fluorescent protein (GFP) expression was observed after microinjection of complexes of polymer containing c-Src-targeting peptides and GFP-encoding DNA into A431 cells at the nitrogen/phosphate (N/P) ratio of 1.0. GFP was not expressed in cells microinjected with negative control polymer/DNA complex. Direct injection of complexes of polymer containing c-Src-targeting peptides and luciferase-encoding DNA at N/P ratios of 1.0 and 2.0 into tumor-bearing mice resulted in luciferase expression in A431 tumors but not in normal skin tissues. No luciferase expression was observed in A431 tumors or skin tissues after injection of control polymer/DNA complex. These results indicate that our gene delivery carrier enables activated c-Src-specific gene expression.