A peptide competing with VEGF165 binding on neuropilin-1 mediates targeting of a chlorin-type photosensitizer and potentiates its photodynamic activity in human endothelial cells.

Abstract

Destruction of the neovasculature is essential for efficient tumor eradication by photodynamic therapy (PDT). Since the over-expression of receptors for vascular endothelial growth factor (VEGF) is correlated with tumor angiogenesis and subsequent growth, we conjugated a photosensitizer (5-(4-carboxyphenyl)-10,15,20-triphenyl-chlorin, TPC), via a spacer (6-aminohexanoic acid, Ahx), to a VEGF receptor-specific heptapeptide (ATWLPPR). ATWLPPR and TPC-Ahx-ATWLPPR bound exclusively to neuropilin-1 (NRP-1) recombinant chimeric protein (IC50=19 and 171 microM, respectively) but were devoid of affinity for VEGF receptor type 2 (VEGFR-2, KDR), to which ATWLPPR was initially thought to bind. TPC-Ahx-ATWLPPR was incorporated up to 25-fold more in human umbilical vein endothelial cells (HUVEC) than TPC over a 24-h period, and the addition of 8 mM ATWLPPR induced a significant decrease of this uptake (P<0.05), corroborating a receptor-mediated incorporation. Slightly less cytotoxic in the dark, TPC-Ahx-ATWLPPR exhibited enhanced in vitro photodynamic activity (10.4-fold), compared to TPC. Pharmacokinetic analysis in nude mice xenografted with U87 human malignant glioma cells revealed relevant tumor levels as soon as 1 h after intravenous injection of TPC-Ahx-ATWLPPR, and a rapid elimination from the blood compartment. Moreover, TPC-Ahx-ATWLPPR was not degraded in vivo up to 2 h after intravenous injection. Taken together, our results demonstrate that TPC-Ahx-ATWLPPR is a much more potent photosensitizer in vitro than TPC, in NRP-1-expressing cells. Thus, it may efficiently potentiate the vascular effect of PDT in vivo.

• Authors: Loraine Tirand, Céline Frochot, Régis Vanderesse, Noémie Thomas, Eric Trinquet, Sophie Pinel, Marie-Laure Viriot, François Guillemin, Muriel Barberi-Heyob
• Journal: Journal of controlled release : official journal of the Controlled Release Society (J Control Release) Vol. 111 Issue 1-2 Pg. 153-64 (Mar 10 2006) ISSN: 0168-3659 [Print] Netherlands
• PMID: 16423422 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• 5-(4-carboxyphenyl)-10,15,20-triphenylchlorin
• Oligopeptides
• Photosensitizing Agents
• Porphyrins
• VEGFA protein, human
• Vascular Endothelial Growth Factor A
• Neuropilin-1
• chlorin
• Receptors, Vascular Endothelial Growth Factor

Topics

• Animals
• Blotting, Western
• Cell Line
• Cell Line, Tumor
• Cell Survival (drug effects, radiation effects)
• Drug Delivery Systems (methods)
• Drug Synergism
• Endothelial Cells (cytology, drug effects, metabolism)
• Female
• Glioblastoma (drug therapy, pathology)
• Humans
• Light
• Mice
• Mice, Nude
• Neuropilin-1 (metabolism)
• Oligopeptides (administration & dosage, metabolism, pharmacokinetics)
• Photochemotherapy (methods)
• Photosensitizing Agents (administration & dosage, pharmacology, therapeutic use)
• Porphyrins (administration & dosage, pharmacology, therapeutic use)
• Protein Binding
• Receptors, Vascular Endothelial Growth Factor (metabolism)
• Vascular Endothelial Growth Factor A (metabolism)
• Xenograft Model Antitumor Assays (methods)