Abstract 5653: A novel cationic peptide nanoparticle-based gene therapy with angiotensin II type 2 receptor gene significantly attenuates growth of lung adenocarcinoma xenografts in mouse model

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL A successful gene therapy requires targeted gene delivery, high gene transfection efficiency at the target tissue, and low toxicity of the vectors. We have demonstrated that the HIV-1 TAT peptide is suggested to be an effective gene delivery vector in various cultured cells (Baoum, et al., Pharm Res, 2009; Baoum, et al., Int J Pharm, 2011). The objectives of the present study were to examine the gene transfection efficacy of modified TAT peptide nanoparticle (two TAT peptides connected in tandem i.e. dTAT NP) as a vector, and to examine the efficiency of the tumor-targeted gene delivery after intratracheal administration. Expression efficiency of the dTAT NP encapsulating luciferase or angiotensin II type 2 receptor (AT2R) plasmid DNA (pDNA) was evaluated using Lewis Lung carcinoma (LLC) cells in culture and orthotopic autografts in C57BL/6 mice lungs. Cell culture studies clarified that the dTAT NP caused effective gene transfection with negligible cytotoxicity until approximately 4 mg dTAT/mL (IC50= 4.075 mg/mL), whereas polyethyleneimine (PEI) showed much stronger cytotoxicity (IC50= 0.028 mg/mL). The in vitro study also revealed that the addition of calcium and glucose to the dTAT/pDNA NP caused effective DNA transfection. The in vitro transfection of pAT2R by dTAT NP caused marked attenuation of the growth of LLC cells. Immunohistochemical analysis of the in vitro transfection and in vivo mouse gene expression studies with dTAT/luciferase pDNA NP revealed that dTAT NP vector successfully delivered the dTAT/pDNA complex to the tumor tissues and caused gene expression primarily in the tumor cells and bronchial epithelium. Gene expression in the tumor tissues lasted for at least 14 days post-administration. Bolus intratracheal administration of dTAT/pAT2R as well as dTAT/pTRAIL markedly attenuated tumor growth of LLC autografts in the mouse lungs. Immunohistochemical analysis of dissected tumors revealed that the AT2R expression was predominantly located in the tumor cells of the LLC tumor bearing mouse lung. Apoptotic index was significantly higher in the treated tumors than PBS or luciferase treated control tumors, suggesting that AT2R pDNA was successfully delivered to the tumor tissues by dTAT NP vector and caused apoptosis of tumor cells. Taken together, the current study suggests that a gene delivery system using intratracheal administration of dTAT/pAT2R NP offers an effective strategy for lung cancer gene therapy. This work was supported by the Kansas State University (KSU) Terry C. Johnson Center for Basic Cancer Research, KSU College of Veterinary Medicine Dean's Fund, NIH P20 RR017686, p20 RR1556, R21CA135599 and Kansas Bioscience Authority Collaborative Cancer Research grant. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5653. doi:1538-7445.AM2012-5653