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.
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.
Tirand
Loraine
L
Centre Alexis Vautrin-CRAN, UMR 7039 CNRS-UHP-INPL, Avenue de Bourgogne, F-54511 Vandoeuvre-les-Nancy Cedex, France.
Frochot
Céline
C
Vanderesse
Régis
R
Thomas
Noémie
N
Trinquet
Eric
E
Pinel
Sophie
S
Viriot
Marie-Laure
ML
Guillemin
François
F
Barberi-Heyob
Muriel
M
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D016503:Drug Delivery Systems / Q000379:methods; D004357:Drug Synergism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005909:Glioblastoma / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D008027:Light; D051379:Mice; D008819:Mice, Nude; D039942:Neuropilin-1 / Q000378:metabolism*; D009842:Oligopeptides / Q000008:administration & dosage* / Q000378:metabolism / Q000493:pharmacokinetics; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D011166:Porphyrins / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D011485:Protein Binding; D040262:Receptors, Vascular Endothelial Growth Factor / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays / Q000379:methods
C513508:5-(4-carboxyphenyl)-10,15,20-triphenylchlorin; D009842:Oligopeptides; D017319:Photosensitizing Agents; D011166:Porphyrins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D039942:Neuropilin-1; C006969:chlorin; D040262:Receptors, Vascular Endothelial Growth Factor