Combined Local Pulmonary and Systemic Delivery of AT2R Gene by Modified TAT Peptide Nanoparticles Attenuates Both Murine and Human Lung Carcinoma Xenografts in Mice

To evaluate the potential of cell-penetrating peptide-based delivery of apoptosis-inducer gene in cancer therapy, a modified HIV-1 TAT peptide (dimerized TAT peptide, dTAT) was studied. The dTAT and plasmid DNA (pDNA) complexes (dTAT-pDNA) were condensed using calcium chloride (dTAT-pDNA-Ca²⁺). This simple nonviral formulation approach showed high levels of gene expression in vitro without any cytotoxicity. In mouse studies, a single intratracheal (IT) aerosol spray or 2 intravenous (IV) injections of the dTAT, apoptosis-inducer gene, angiotensin II type 2 receptor (AT2R), and Ca²⁺ complexes (dTAT-pAT2R-Ca²⁺) significantly attenuated the acutely growing mouse Lewis lung carcinoma allografts in mouse lungs. Furthermore, single IT (p = 0.054) and the combination of IT and IV (p < 0.05) administrations of dTAT-pAT2R-Ca²⁺ markedly attenuated slowly growing and relatively large-sized H358 human bronchioloalveolar carcinoma xenografts in mouse lungs. These results indicate that the dTAT-pDNA-Ca²⁺ effectively delivered the gene to cancer cells by either IT or IV administration although the local pulmonary delivery of the dTAT-pAT2R-Ca²⁺ showed more effective growth inhibition of orthotopic lung cancer grafts. Thus, the present study offers preclinical proof of concept that a dTAT-based nonviral gene delivery method via IT administration may be an effective lung cancer gene therapy.