HPMA-copolymer conjugates targeted to tumor endothelium using synthetic oligopeptides

Abstract

Synthesis and characterization of N-(2-hydroxypropyl)methacrylamide (HPMA)-copolymer–based drug carriers targeted on specific receptors in the membrane of endothelial cells by oligopeptides (GRGDG, cyclo(RGDfK), and PHSCN) are described in this study. The copolymers containing targeting oligopeptides bound to the polymer via dodeca(ethylene glycol) spacer showed a receptor-specific time-dependent uptake with selected endothelial cell lines. The polymers were labeled with a fluorescent dye to enable monitoring of the interaction of the polymer conjugate with cells using fluorescence microscopy. Cellular uptake and apoptosis induction have been studied in vitro using various cell lines (EA.hy926, 3T3, SW620, and EL4). In vivo accumulation of the conjugate specifically targeted with cyclo(RGDfK) within the tumor vasculature was detected using fluorescence intravital microscopy in mice. The conjugate targeted by cyclo(RGDfK) was accumulated preferentially in the periphery of the growing tumor suggesting that the cyclo(RGDfK) peptide targets the polymer conjugate to the site of neoangiogenesis, rather than to the tumor mass.

Keywords::

• Neoangiogenesis
• drug delivery system
• HPMA copolymers
• peptide targeting

Acknowledgments

The authors gratefully acknowledge the support from the Grant Agency of the Academy of Science of the Czech Republic, grant nos. IAAX00500803 and IAA400200702, and the Grant Agency of the Czech Republic, grant no. 203/08/0543.

Declaration of interest: The authors report no conflict of interests. The authors alone are responsible for the content and writing of the paper.