Novel PAMAM-PEG-Peptide Conjugates for siRNA Delivery Targeted to the Transferrin and Epidermal Growth Factor Receptors.

Koldo Urbiola,Ernst Wagner,Laura Blanco-Fernández,Wolfgang Rödl,Conchita Tros De Ilarduya,Manfred Ogris

doi:10.3390/jpm8010004

Abstract

The transferrin (TfR) and epidermal growth factor receptors (EGFR) are known to be overexpressed on the surface of a wide variety of tumor cells. Therefore, the peptides B6 (TfR specific) and GE11 (targeted to the EGFR) were linked to the PAMAM (polyamidoamine) structure via a polyethylenglycol (PEG) 2 kDa chain with the aim of improving the silencing capacity of the PAMAM-based dendriplexes. The complexes showed an excellent binding capacity to the siRNA with a maximal condensation at nitrogen/phosphate (N/P) 2. The nanoparticles formed exhibited hydrodynamic diameters below 200 nm. The zeta potential was always positive, despite the complexes containing the PEG chain in the structure showing a drop of the values due to the shielding effect. The gene silencing capacity was assayed in HeLa and LS174T cells stably transfected with the eGFPLuc cassette. The dendriplexes containing a specific anti luciferase siRNA, assayed at different N/P ratios, were able to mediate a mean decrease of the luciferase expression values of 14% for HeLa and 20% in LS174T cells, compared to an unspecific siRNA-control. (p < 0.05). In all the conditions assayed, dendriplexes resulted to be non-toxic and viability was always above 75%.

Highlights

IntroductionResearch has focused on the improvement of non-viral systems for gene therapy
During the last years, research has focused on the improvement of non-viral systems for gene therapy
The epidermal growth factor receptor (EGFR) and transferrin receptor (TfR) are two of the most used targeted sites for specific delivery of nucleic acids, since they are overexpressed on the surface of tumoral cells compared with healthy tissues and have demonstrated good activity for drug and gene delivery [1]

Summary

Introduction

Research has focused on the improvement of non-viral systems for gene therapy. In order to achieve better vectors with enhanced gene delivery activity, different ligands have been included in the formulations. The epidermal growth factor receptor (EGFR) and transferrin receptor (TfR) are two of the most used targeted sites for specific delivery of nucleic acids, since they are overexpressed on the surface of tumoral cells compared with healthy tissues and have demonstrated good activity for drug and gene delivery [1]. The gene transfer capacity of targeted non-viral vectors and novel drug delivery systems including specific ligands has proven to be effective in increasing internalization and delivery of the cargo in vitro and in vivo [2]. The peptides GE11 and B6 do not contain more than 15 amino acids and bind

Methods

Discussion

Conclusion