Application of bioengineered elastin-like polypeptide-based system for targeted gene delivery in tumor cells

Successful gene delivery depends on the entry of negatively charged DNAs and oligonucleotides across the various barriers of the tumor cells and localization into the nucleus for its transcription and protein translation. Here, we have reported a thermal responsive self-assemble and highly biocompatible, targeted ELP-based gene delivery system. These systems consist of cell-penetrating peptides, Tat and single or multiple repeats of IL-4 receptor targeting peptide AP-1 along the backbone of ELP. Cell-penetrating peptides were introduced for nuclear localization of genes of interest, AP-1 for targeting IL-4R highly expressed tumor cells and ELP for stable condensation favoring protection of nucleic acids. The designed multidomain fusion ELPs referred to as Tat-ELP, Tat-A₁E₂₈ and Tat-A₄V₄₈ were employed to generate formulation with pEGFP-N1. Profound formulation of stable complexes occurred at different molar ratios owing to electrostatic interactions of positively charged amino acids in polymers with negatively charged nucleic acids. Among the complexes, Tat-A₄V₄₈ containing four copies of AP-1 showed maximum complexation with pEGFP-N1 in lower molar ratio. The polymer-pEGFP complexes were further analyzed for its transfection efficiency in different cancer cell lines. Both the targeted polymers, Tat-A₄V₄₈ and Tat-A₁E₂₈ upon transfection displayed significant EGFP-expression with low toxicity in different cancer cells. Therefore, both Tat-A₄V₄₈ and Tat-A₁E₂₈ can be considered as novel transfection system for successful gene delivery with therapeutic applications.