Gene delivery attracted much attention in tumor therapy. The targeted delivery, cellular uptake and high efficient gene expression in vivo are important issues for non-viral gene delivery vectors in cancer therapy. To solve these issues, we designed a novel tumor targeted gene nano delivery system based on EGFR targeting strategy. Nimotuzumab (h-R3), a humanized monoclonal antibody (mAb), was introduced to nano-complexes of PAMAM dendrimer and DNA (dendriplex) to form self-assembled h-R3-dendriplex to enhance transgene expression in EGFR-overexpressing tumor cells. Three different cell lines (EGFR-negative 293T, EGFR-expressing MCF-7 and EGFR-overexpressing HepG2) were used for in vitro experiments. The formulation, size, zeta potential, mophophlogy and cytotoxicity of dendriplexes and h-R3-dendriplexes were evaluated by agarose gel retardation assay, dynamic light scattering, transmission electron microscopy and MTT assay. The in vitro gene transfection and cell uptake were detected by flow cytometry and confocal microscopy. The in vivo distribution and gene delivery of dendriplexes and h-R3-dendriplexes were determined by fluorescence imaging and confocal observation of frozen section. Dendriplexes and h-R3-dendriplexes represented excellent DNA encapsulation ability, formed unique nanostructures and had low cytotoxicity. Compared to dendriplexes, h-R3-dendriplexes presented high gene transfection efficiency and had excellent cellular uptake and endosome escape ability on the EGFR-overexpressing HepG2 cell line. In vivo fluorescence imaging and ex vivo confocal results revealed that h-R3-dendriplex showed higher fluorescence intensity in the tumors than dendriplex at the same N/P ratio. These results indicate that the h-R3-dendriplex represents a great potential to be used as efficient targeting gene delivery carrier in cancer therapy.
Key words: dendriplexes, h-R3, gene delivery, EGFR-overexpressing tumor cells