Targeted delivery in breast cancer cells via iodine: nuclear localization sequence conjugate.

The nonviral vector with iodine-nuclear localization sequence (namely, NLS-I) targeting breast cancer cells was fabricated. Ternary complexes were formed via charge interactions among NLS-I peptides, PEI 1800, and DNA, and we investigated their cellular internalization, nuclear accumulation as well as transfection efficiency. All the experiments were assessed by employing MCF-7 cells that express sodium/iodide symporter and HeLa cells that lack the expression of the symporter. In MCF-7 cells, cell internalization and nuclear accumulation of NLS-I was markedly increased compared to that in NLS. In addition, compared to that of the PEI1800/DNA complex, PEI1800/DNA/NLS-I complexes exhibited much enhanced luciferase reporter gene expression by up to 130-fold. By contrast, in HeLa cells, the evident improvements of cellular internalization, nuclear accumulation, and transfection efficiency by NLS-I were not observed. This study demonstrates an alternative method to construct a nonviral delivery system for targeted gene transfer into breast cancer cells.

PEGylated peptide based reductive polycations as efficient nonviral gene vectors.

To overcome the critical barriers in gene delivery, a series of reducible polycations (RPCs) based on low molecular weight (LMW) peptides, i.e. PolyHK6 H, PolyHK6 H-mPEG1 , PolyHK6 H-mPEG2 , and PolyHK6 H-mPEG3 , with different poly(ethylene glycol) (PEG) contents, are synthesized and evaluated as nonviral gene vectors. All the RPCs exhibit lower cytotoxicity compared with 25 kDa polyethyleneimine (PEI) and PEGylated PEI (PEI-mPEG: PEI-mPEG1 , PEI-mPEG2 , and PEI-mPEG3 ). PolyHK6 H-mPEG1 and PolyHK6 H-mPEG2 can bind and condense plasmid deoxyribonucleic acid (pDNA) efficiently with a particle size of about 200 nm. Moreover, they display much higher transfection efficiency than that of 25 kDa PEI especially in serum-supplemented medium. Moreover, PolyHK6 H-mPEG1 has equal transfection efficiency with PEI-mPEG1 which is optimal in the PEI-mPEG, but PolyHK6 H-mPEG1 exhibits significantly lower cytotoxicity than PEI-mPEG1 . This is attributed to the fact that inter-peptide disulfide bonds can increase the stability of RPCs/pDNA complexes in extracellular environment and thereafter cleave in cytoplasm to facilitate the release of pDNA in intracellular environment. The PEGylated RPCs demonstrate here improved intracellular gene transfer performance and will have great potential applications in vivo.

Tyroserleutide-based gene vector for suppressing VEGF expression in cancer therapy.

A small interfering RNA (siRNA) plasmid DNA (pYr-1.1-hU6-EGFP-siVEGF) was constructed and used for suppressing vascular endothelial growth factor (VEGF) expression and inhibiting tumor growth. Then, a (tyrosyl-seryl-leucine)-polyethyleneimine-poly(ethylene glycol) (YSL-PEI-PEG) conjugate was designed and synthesized as a gene carrier for the delivery of pYr-1.1-hU6-EGFP-siVEGF plasmid. The therapeutic peptide YSL was conjugated to PEI to improve the anti-cancer efficiency, and the PEG chain was introduced to reduce the serum protein adsorption and improve the stability of the complex in the systemic circulation. It was found that YSL-PEI-PEG could efficiently condense plasmid DNA when the vector/DNA weight ratio was higher than 2. Compared with PEI 25 kDa, YSL-PEI-PEG exhibited higher transfection efficiency and lower cytotoxicity. More importantly, the results showed that the gene delivery system owned strong ability to inhibit cancer cell proliferation in vitro and tumor growth in vivo. YSL-PEI-PEG has great potential as a gene vector for clinical applications.