Tumor-specific delivery of anticancer nucleic acids by anti-EGF receptor immunonanoparticles

Abstract

Cancer gene therapy is the treatment of cancers by transferring therapeutic genes (plasmid DNA, micro RNA or small interfering RNA) with gene delivery systems. The drawbacks of gene delivery systems in the issues of safety and transfection efficiency make their clinical applications difficult. Liposomal gene delivery systems have been considered to be relatively safer, less immunogenic and non-infectious than viral gene delivery systems. Typically, cationic liposomes have been widely utilized for in vitro and in vivo gene transfection because of easy and stable formation of liposome-DNA complexes called lipoplexes. In recent years, the liposomal gene delivery systems have been improved in terms of transfection efficiency and stability in vivo. For example, virosomes, fusogenic viral envelop proteins reconstituted in liposomal vesicles, were more effective in transfection to various cells and tissues than other conventional cationic lipoplexes. However, gene transfection efficiency of liposomal systems still needs to be further improved for clinical applications. In this study, anti-epithermal growth factor receptor (EGFR) immunonanoparticles (immunoliposomes, immunovirosomes, immunolipoplexes and immunoviroplexes) were developed for EGFR-directed gene delivery to cancer cells. The four different types of EGFR-targeted liposomal systems were finally constructed by conjugation of Cetuximab, anti-EGFR monoclonal antibody, to PEG termini on the liposomal surface. The resulting anti-EGFR antibody-conjugated immunonanoparticles were able to effectively deliver genes (pDNA and siRNA) to EGFR-positive cancer cells (A549 and SK-OV-3 cells), but not to EGFR-negative ones (MCF-7 and B16BL6). Especially, the anti-EGFR immunoviroplexes exhibited the most efficient transfection to EGFR-expressing tumor cells than the others. The anti-EGFR immunonanoparticles were able to more selectively deliver to SK-OV-3 tumors xenografted in mice than conventional cationic DMKE/Chol lipoplexes. The two different types of anticancer genes (pDNA; IL12 gene and/or salmosin gene, siRNA; vimentin siRNA and/or JAK3 siRNA) were encapsulated in anti-EGFR immunolipoplexes and anti-EGFR immunoviroplexes and then intravenously injected to the SK-OV-3 tumor-xenografted mouse model. The gene transfected mice were also treated with anti-cancer drug, doxorubicin. According to the experimental data, the anti-EGFR immunonanoparticles containing both types of anticancer genes were more effective in inhibition of tumor growth and metastasis. In addition, the combined treatment with doxorubicin was able to synergistically inhibit SK-OV-3 tumor growth in mice. Among the anti-EGFR immunononoparticles, the anti-EGFR immunoviroplexes exhibited the most efficient EGFR-specific transfection, resulting in the most effective therapeutic efficacy. This study suggests that the anti-EGFR immunonanoparticles, specially the anti-EGFR immunoviroplex formulation, would be useful as an efficient tumor-specific gene delivery system for cancer gene therapy. Also, combination of conventional chemotherapy and tumor-directed anticancer gene therapy can be an acceptable modality for anticancer therapy.