A lack of safe, effective methods of delivery of gene therapy remains a barrier to clinical implementation. Now, a nonviral cell-penetrating peptide consisting of polylysine K9, complexed with angiotensin II type 2 receptor (AGTR2) plasmid DNA and condensed with calcium chloride, has been shown to effectively deliver the AGTR2 gene to various cancer cell lines. This effect was confirmed in orthotopic cancer grafts in syngeneic mice, in which gene therapy was successfully delivered, either using intravenous injection or intratracheal spray. AGTR2 expression was predominantly detected in cancer cells or bronchial epithelial cells and, importantly, was associated with attenuated growth of lung tumours.