Prostate cancer cell–specific VEGF siRNA delivery system using cell targeting peptide conjugated polyplexes

Abstract

A polymeric gene carrier was developed to deliver vascular endothelial growth factor (VEGF) small interfering RNA (siRNA) for prostate cancer cells in a target-specific manner. Prostate cancer–binding peptide (PCP) was conjugated with polyethylenimine (PEI) via a poly(ethylene glycol) (PEG) linker (PEI–PEG–PCP). The PEI–PEG–PCP conjugate could effectively condense siRNA to form stable polyelectrolyte complexes (polyplexes) with an average diameter of approximately 150 nm in an aqueous solution. VEGF siRNA/PEI–PEG–PCP polyplexes exhibited significantly higher VEGF inhibition efficiency than PCP-unmodified polycationic carriers (PEI–PEG or PEI) in human prostate carcinoma cells (PC-3 cells). The enhanced gene silencing activity of VEGF siRNA/PEI–PEG–PCP was maintained even under serum conditions, owing to the steric stabilization of the polyplexes with hydrophilic PEG grafts. Confocal microscopic studies revealed that the siRNA/PEI–PEG–PCP polyplexes were delivered into PC-3 cells in a PCP ligand–specific manner.