Search

A series of novel nonviral vectors targeting the HER-2/neu gene product human epidermal growth factor receptor-2 (HER2) were constructed and evaluated in breast cancer cell lines to optimize vector formulation for receptor-specific gene transfer. These vectors were DNA/polycation complexes (polyplexes) prepared by mixing, at varying ratios, plasmid DNA carrying a luciferase reporter gene to HerPEI, which is a conjugate of linear polyethylenimine (PEI), a cationic polymer, and trastuzumab (Herceptin®), a HER2-specific monoclonal antibody. Transfection studies were carried out in both HER2 overexpressing Sk-Br-3 and HER2 low-expressing MDA-MB-231 breast cancer cells. The HerPEI polyplexes showed significantly greater transfection activity up to 20-folds than nonderivatized PEI-based polyplexes in the Sk-Br-3 cells. The transfection efficiency of targeted polyplexes was dependent on the trastuzumab:PEI ratio and can be blocked by excess free trastuzumab, suggesting HER2-mediated gene delivery. In contrast, no significant difference in transfection activities was observed between HER2-targeted and nontargeted polyplexes in the HER2 low-expressing MDA-MB-231 cells. The transfection efficiency of HerPEI polyplexes was retained in serum-containing medium. In summary, HerPEI polyplexes have shown promising HER2 receptor-specific gene transfer properties and warrant further evaluation as a tumor-targeted vector for gene therapy. [Copyright &y& Elsevier]

Abstract: Lactosylated gramicidin-containing lipid nanoparticles (Lac-GLN) were developed for delivery of anti-microRNA-155 (anti-miR-155) to hepatocellular carcinoma (HCC) cells. MiR-155 is an oncomiR frequently elevated in HCC. The Lac-GLN formulation contained N-lactobionyl-dioleoyl phosphatidylethanolamine (Lac-DOPE), a ligand for the asialoglycoprotein receptor (ASGR), and an antibiotic peptide gramicidin A. The nanoparticles exhibited a mean particle diameter of 73nm, zeta potential of +3.5mV, anti-miR encapsulation efficiency of 88%, and excellent colloidal stability at 4°C. Lac-GLN effectively delivered anti-miR-155 to HCC cells with a 16.1- and 4.1-fold up-regulation of miR-155 targets C/EBPβ and FOXP3 genes, respectively, and exhibited significant greater efficiency over Lipofectamine 2000. In mice, intravenous injection of Lac-GLN containing Cy3-anti-miR-155 led to preferential accumulation of the anti-miR-155 in hepatocytes. Intravenous administration of 1.5mg/kg anti-miR-155 loaded Lac-GLN resulted in up-regulation of C/EBPβ and FOXP3 by 6.9- and 2.2-fold, respectively. These results suggest potential application of Lac-GLN as a liver-specific delivery vehicle for anti-miR therapy. [Copyright &y& Elsevier]

pH-sensitive liposomes are designed to promote efficient release of entrapped agents in response to low pH. In this study, novel pH-sensitive liposomes consisting of cationic/anionic lipid combinations are evaluated for intracellular drug and gene delivery. First, liposomes composed of egg phosphatidylcholine, dimethyldioctadecylammonium bromide (DDAB), cholesteryl hemisuccinate (CHEMS), and Tween-80 (25:25:49:1, mol/mol) were shown to stably entrap calcein at pH 7.4 and undergo rapid content release and irreversible aggregation under acidic pH. Compared to pH-sensitive liposomes incorporating dioleoylphosphatidylethanolamine, these liposomes showed improved retention of pH-sensitivity in the presence of serum. The folate receptor (FR), which is amplified in a wide variety of human tumors, could be targeted by incorporating 0.1 mol% folate-polyethyleneglycol-phosphatidylethanolamine (f-PEG-PE) into liposomes. f-PEG-PE has been shown to facilitate FR-mediated endocytosis of liposomes into KB human oral cancer cells, which express amplified FR. FR-targeted pH-sensitive liposomes produced increased cytosolic release of entrapped calcein, as shown by fluorescence microscopy, and enhanced cytotoxicity of entrapped cytosine-β-d-arabinofuranoside, as shown by an 11-fold reduction in the IC50 in KB cells, compared to FR-targeted non-pH-sensitive liposomes. Furthermore, FR-targeted pH-sensitive liposomes composed of DDAB/CHEMS/f-PEG-PE, combined with polylysine-condensed plasmid DNA, were shown to mediate FR-specific delivery of a luciferase reporter gene into KB cells in the presence of 10% serum. These findings suggest that cationic lipid-containing pH-sensitive liposomes, combined with FR targeting, are effective vehicles for intracellular drug and gene delivery. [Copyright &y& Elsevier]