[Show abstract][Hide abstract] ABSTRACT: Blocking angiogenesis is an attractive strategy to inhibit tumor growth, invasion, and metastasis. We describe here the structure and the biological action of a new cyclic peptide derived from vascular endothelial growth factor (VEGF). This 17-amino acid molecule designated cyclopeptidic vascular endothelial growth inhibitor (cyclo-VEGI, CBO-P11) encompasses residues 79-93 of VEGF which are involved in the interaction with VEGF receptor-2. In aqueous solution, cyclo-VEGI presents a propensity to adopt a helix conformation that was largely unexpected because only beta-sheet structures or random coil conformations have been observed for macrocyclic peptides. Cyclo-VEGI inhibits binding of iodinated VEGF165 to endothelial cells, endothelial cells proliferation, migration, and signaling induced by VEGF165. This peptide also exhibits anti-angiogenic activity in vivo on the differentiated chicken chorioallantoic membrane. Furthermore, cyclo-VEGI significantly blocks the growth of established intracranial glioma in nude and syngeneic mice and improves survival without side effects. Taken together, these results suggest that cyclo-VEGI is an attractive candidate for the development of novel angiogenesis inhibitor molecules useful for the treatment of cancer and other angiogenesis-related diseases.
Full-text · Article · Oct 2003 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: A few peptide residues in structurally important locations often determine biological functions of proteins implicated in the regulation of angiogenesis. We have shown recently that the short COOH-terminal segment PF-4(47-70) derived from platelet factor 4 (PF-4) is the smallest sequence that conserves potent antiangiogenic activity in vitro and in vivo. Here we show that modified COOH-terminal PF-4 peptides containing the sequence ELR (or related DLR), a critical domain present in proangiogenic chemokines, surprisingly elicit several times greater antiangiogenic potential than the original peptide. The modified peptides inhibit binding of iodinated vascular endothelial growth factor and fibroblast growth factor 2 to endothelial cell receptors, endothelial cell proliferation, migration, and microvessel assembly in the rat aortic ring model at lower doses than PF-4(47-70). On the differentiated chick chorioallantoic membrane, topical application of 40 micro g of modified peptides potently reduces capillary angiogenesis induced by vascular endothelial growth factor(165), a dose where peptide PF-4(47-70) was inactive. Established intracranial glioma in nude mice decreased significantly in size when treated locally with a total dose of 250 micro g of peptide PF-4(47-70)DLR (n = 10) compared with the same dose of the original PF-4(47-70) peptide (n = 10) or controls (n = 30). Tailored PF-4 peptides represent a new class of antiangiogenic agents with a defined mode of action and a strong in vivo activity.
[Show abstract][Hide abstract] ABSTRACT: Platelet factor-4 is a protein belonging to the family of ELR-negative CXC chemokines which binds to fibroblast growth factor
and inhibits its mitogenic activity. Platelet factor-4 also inhibits tumor growth by mechanisms involving antiangiogenesis.
Antiangiogenic activity in vitro has also been shown for the 24-residue C-terminal fragment of the protein, which decreases the affinity between basic fibroblast
growth factor and its cell-surface receptor. In this study, the preferential conformation of this fragment in solution has
been determined and has been found to be composed of two helical subdomains. In addition, we show that the fragment forms
a specific 1:1 complex with acidic and basic fibroblast growth factors and that both subdomains are probably required for
inhibition of fibroblast growth factor-driven mitogenesis. Finally, we show that the binding of the fragment alters the structure
of the fibroblast growth factors, although some of such alterations do not seem related with the inhibition of mitogenic activity.
Since this fragment has recently been shown to inhibit fibroblast growth factor-induced angiogenesis in vivo when injected intraperitoneally, these results are relevant for developing new antiangiogenic treatments.
Preview · Article · Oct 2001 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: Platelet factor 4 (PF-4) is a CXC-chemokine with strong anti-angiogenic properties. We have shown previously that PF-4 inhibits angiogenesis by associating directly with fibroblast growth factor 2 (FGF-2), inhibiting its dimerization, and blocking FGF-2 binding to endothelial cells. We now have characterized a small peptide domain (PF-447-70) derived from the C-terminus of PF-4, which conserves anti-angiogenic effects of the parent protein. PF-447-70 inhibited internalization of 125I-FGF-2 by endothelial cells in a time-dependent manner. The peptide reduced FGF-2-stimulated cell migration to control levels in wounded monolayers of bovine capillary endothelial cells. PF-447-70 also reduced FGF-2 induced phosphorylation of MAP kinases ERK-1 and ERK-2, which are essential for migration and survival of endothelial cells. In a serum-free ex vivo angiogenesis assay, the peptide blocked microvessel outgrowth by 89%. A single amino acid substitution within PF-447-70 abolished all inhibitory activities. To simulate a real anti-angiogenic treatment situation, we administered PF-447-70 systemically to mice implanted subcutaneously with FGF-2 containing gelatin sponges with the result of sparse, scattered, and immature vessel growth. The small peptide fragment derived from the angio-inhibitory CXC-chemokine PF-4 might be used as a starting point to develop anti-angiogenic designer drugs for angiogenesis-dependent pathologies such as cancer, diabetic retinopathy, and rheumatoid arthritis.
Full-text · Article · Apr 2001 · The FASEB Journal