Synthesis, Characterization, and Biological Evaluation of a Dual‐Action Ligand Targeting α_vβ₃ Integrin and VEGF Receptors

Abstract

A dual-action ligand targeting both integrin αVβ3 and vascular endothelial growth factor receptors (VEGFRs), was synthesized via conjugation of a cyclic peptidomimetic αVβ3 Arg-Gly-Asp (RGD) ligand with a decapentapeptide. The latter was obtained from a known VEGFR antagonist by acetylation at the Lys13 side chain. Functionalization of the precursor ligands was carried out in solution and in the solid phase, affording two fragments: an alkyne VEGFR ligand and the azide integrin αVβ3 ligand, which were conjugated by click chemistry. Circular dichroism studies confirmed that both the RGD and VEGFR ligand portions of the dual-action compound substantially adopt the biologically active conformation. In vitro binding assays on isolated integrin αVβ3 and VEGFR-1 showed that the dual-action conjugate retains a good level of affinity for both its target receptors, although with one order of magnitude (10/20 times) decrease in potency. The dual-action ligand strongly inhibited the VEGF-induced morphogenesis in Human Umbilical Vein Endothelial Cells (HUVECs). Remarkably, its efficiency in preventing the formation of new blood vessels was similar to that of the original individual ligands, despite the worse affinity towards integrin αVβ3 and VEGFR-1.

Multivalency Increases the Binding Strength of RGD Peptidomimetic‐Paclitaxel Conjugates to Integrin αVβ3

“…Later on, the functionalized ligand cyclo [DKP‐RGD]‐CH 2 NH 2 (compound 2 in Figure ), featuring a primary amino group, was prepared . The latter compound was conjugated to different payloads, such as the anticancer drug paclitaxel (PTX, compound 3 in Figure ), a pro‐apoptotic SMAC (second mitochondria‐derived activator of caspases) mimetic compound and an anti‐angiogenic VEGFR‐targeting decapentapeptide, by means of ester and amide linkages. As a further step, to achieve selective release of PTX in the cancer cell environment, we synthesized conjugates of the cyclo [DKP‐RGD]‐CH 2 NH 2 ligand 2 with paclitaxel ( 3 ) via a 2′‐carbamate with a self‐immolative spacer and the lysosomally cleavable linkers (Val‐Ala and Phe‐Lys dipeptide sequences) .…”

Rational Design of Antiangiogenic Helical Oligopeptides Targeting the Vascular Endothelial Growth Factor Receptors

“…A chemiluminescent assay to determine the inhibition of complex formation between VEGF-A (isoform VEGF 165 ) and the extracellular domain of VEGFR-1 (Goncalves et al, 2007; García-Aranda et al, 2013) had been previously employed in our group (Zanella et al, 2015). VEGF-C (from which analogue 1 was derived) is not selective for VEGFR-1 (Su et al, 2007), but unfortunately the same assay protocol turned out to be ineffective with VEGFR-2, at least in our hands.…”

“…In 2011, D'Andrea and coworkers developed a α-helical decapentapeptide based on the natural sequence of VEGF-A, with potent inhibitory activity against VEGF-stimulated angiogenesis in vivo (Basile et al, 2011; Diana et al, 2013). Because of its synthetic accessibility and antiangiogenic properties, recently some of us selected that peptide to prepare a dual-action compound able to interfere with the integrin α V β 3 -VEGFR-1 cross-talk (Zanella et al, 2015). This conjugate was able to bind in vitro both integrin α V β 3 and VEGFR-1, and exerted a strong antiangiogenic effect in VEGF-stimulated morphogenesis assays on human umbilical vein endothelial cells (HUVECs).…”

Micro-PET imaging of angiogenesis based on 18F-RGD for assessment liver metastasis in colorectal cancer

“…Among all integrins, integrin αvβ3 probably the most strongly involved in the regulation of angiogenesis [9]. The speci cal interaction between integrin αvβ3 and vascular endothelial growth factor receptors (VEGFRs) is considered to be crucial for tumor growth and metastasis [10].…”