Tumor-Penetrating Peptide-Functionalized Redox-Responsive Hyperbranched Poly(amido amine) Delivering siRNA for Lung Cancer Therapy

Biosafety and the targeting ability of gene delivery systems are critical aspects for gene therapy of cancer. In this study, we report the synthesis and use of redox-responsive poly(amido amine) (PAA) with good biocompatibility and biodegradation as a gene carrier material. A tumor-specific tissue penetration peptide, internalizing-RGD (iRGD) was then conjugated to PAA with an amidation reaction. In experiments using H1299 cells, PAA-iRGD was found to have a lower cytotoxicity and higher cellular uptake efficiency compared to PAA. An siRNA, specific to epidermal growth factor receptor (EGFR) that is overexpressed on the lung cancer cell surface and often targeted in lung cancer treatment, was designed to silence EGFR (i.e., siEGFR) for delivery by the gene carrier PAA-iRGD. EGFR gene silencing, apoptosis, antiproliferation, and antitumor effects of PAA-iRGD/siEGFR were evaluated in vitro and in vivo. PAA-iRGD/siEGFR displayed a much higher gene silencing ability compared to PAA and polyethylenimine (25 kDa), significantly inhibited the proliferation and migration of H1299 cells, and elicited significant cell apoptosis. Moreover, intravenously injected PAA-iRGD/siEGFR inhibited lung tumor growth in vivo. These results suggest that PAA-iRGD with good biocompatibility, biodegradation, and targeting ability could be a promising gene delivery system for gene therapy of cancers.