Metabolic profile of a peptide-conjugated chlorin-type photosensitizer targeting neuropilin-1: an in vivo and in vitro study.

Abstract

Because angiogenic endothelial cells of the tumor vasculature represent an interesting target to potentiate the antivascular effect of photodynamic therapy, we recently described the conjugation of a photosensitizer [5-(4-carboxyphenyl)-10,15,20-triphenylchlorin (TPC)], via a spacer [6-aminohexanoic acid (Ahx)], to a vascular endothelial growth factor receptor-specific heptapeptide [H-Ala-Thr-Trp-Leu-Pro-Pro-Arg-OH (ATWLPPR)] and showed that TPC-Ahx-ATWLPPR binds to neuropilin-1. Because peptides often display low stability in biological fluids, we examined the in vivo and in vitro stability of this conjugate by high-performance liquid chromatography and matrix-assisted laser desorption ionization/time of flight mass spectrometry. TPC-Ahx-ATWLPPR was stable in vitro in human and mouse plasma for at least 24 h at 37 degrees C but, following i.v. injection in glioma-bearing nude mice, was degraded in vivo to various rates, depending on the organ considered. TPC-Ahx-A was identified as the main metabolic product, and biodistribution studies suggested that its appearance in plasma mainly resulted from the degradation of the peptidic moiety into organs of the reticuloendothelial system. According to in vitro cell culture experiments, TPC-Ahx-ATWLPPR was also significantly degraded after incorporation in human umbilical vein endothelial cells (HUVEC), mainly into TPC-Ahx-A and to a lesser extent into TPC-Ahx-AT and TPC-Ahx-ATWLPP. TPC-Ahx-ATWLPPR mostly localized into lysosomes, and when HUVEC were treated with the lysosomal enzymes' inhibitor ammonium chloride, this resulted in a significant decrease of the peptide degradation. This study provides essential information for the choice of the time of activation of the photosensitizer (drug-light interval) not to be exceeded and for the future design of more stable molecules.

• Authors: Loraine Tirand, Noémie Thomas, Marc Dodeller, Dominique Dumas, Céline Frochot, Benoît Maunit, François Guillemin, Muriel Barberi-Heyob
• Journal: Drug metabolism and disposition: the biological fate of chemicals (Drug Metab Dispos) Vol. 35 Issue 5 Pg. 806-13 (May 2007) ISSN: 0090-9556 [Print] United States
• PMID: 17283031 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Oligopeptides
• Photosensitizing Agents
• Porphyrins
• Ammonium Chloride
• Neuropilin-1
• chlorin
• Aminocaproic Acid

Topics

• Aminocaproic Acid (chemistry, metabolism)
• Ammonium Chloride (pharmacology)
• Animals
• Cell Line
• Cell Line, Tumor
• Chromatography, High Pressure Liquid
• Endoplasmic Reticulum (metabolism)
• Endothelial Cells (cytology, drug effects, metabolism)
• Female
• Glioma (drug therapy, metabolism, pathology)
• Golgi Apparatus (metabolism)
• Humans
• Injections, Intravenous
• Lysosomes (metabolism)
• Mice
• Mice, Nude
• Microscopy, Confocal
• Molecular Structure
• Neuropilin-1 (antagonists & inhibitors, metabolism)
• Oligopeptides (chemistry, metabolism, pharmacology)
• Photosensitizing Agents (administration & dosage, metabolism, pharmacology)
• Porphyrins (chemistry, metabolism, pharmacology)
• Skin (metabolism)
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
• Xenograft Model Antitumor Assays