Functionalizing αvβ3‐ or α5β1‐Selective Integrin Antagonists for Surface Coating: A Method To Discriminate Integrin Subtypes In Vitro

Rechenmacher, Florian; Neubauer, Stefanie; Mas‐Moruno, Carlos; Simone, Mariarosaria De; Cavalcanti‐Adam, Elisabetta Ada; Spatz, Joachim P.; Fässler, Reinhard; Kessler, Horst

doi:10.1002/anie.201206370

Cited by 83 publications

(92 citation statements)

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“…Moreover, we have already shown that this ligand can be functionalized and used for coating gold and titaniumbased biomaterials in vitro and for selective tumor imaging in vivo with outstanding results. [28][29][30]35 After the incorporation of the methoxypyridine moiety, we investigated the effects of changing the ligand scaffold length by replacing the carboxylic acid moiety, responsible for the crucial interaction with the metal cation at the MIDAS, 36 with a larger functional group. For this reason, we synthesized ligands with a hydroxamic acid.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Pharmacophoric Modifications Lead to Superpotent αvβ3 Integrin Ligands with Suppressed α5β1 Activity

et al. 2014

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The selective targeting of the αvβ3 integrin subtype without affecting the structurally closely related receptor α5β1 is crucial for understanding the details of their biological and pathological functions and thus of great relevance for diagnostic and therapeutic approaches in cancer treatment. Here, we present the synthesis of highly active RGD peptidomimetics for the αvβ3 integrin with remarkable selectivity against α5β1. Incorporation of a methoxypyridine building block into a ligand scaffold and variation of different functional moieties led to αvβ3-antagonistic activities in the low nanomolar or even subnanomolar range. Furthermore, docking studies were performed to give insights into the binding modes of the novel compounds. The presented library comprises powerful ligands for specific addressing and blocking of the αvβ3 integrin subtype, thereby representing privileged tools for integrin-based personalized medicine.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Pharmacophoric Modifications Lead to Superpotent αvβ3 Integrin Ligands with Suppressed α5β1 Activity

et al. 2014

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“…To that end, we applied surface nanopatterning consisting of 8 nm-sized gold nanoparticles with interparticle spacings of 30, 60 or 90 nm, and functionalized with α5β1 and αvβ3 integrin selective ligands 16,21 . On such surfaces, it is possible to control the binding sites of single integrins to the surface, and to modulate the lateral clustering of the receptors during cell adhesion.…”

Section: Discussionmentioning

confidence: 99%

“…To prevent cell adhesion and protein deposition between these nanoparticles, substrates were passivated with polyethylene glycol (PEG) (2000)-triethoxysilane 36 . The nanoparticles were then functionalized with the integrin selective peptidomimetic ligands, which bind either α5β1 or αvβ3 integrins, at a concentration of 25 µM in MilliQ water for 4 hr at room temperature 16 . The unbound ligands were removed by gentle shaking, and the samples were thoroughly rinsed with MilliQ water overnight.…”

Section: Methodsmentioning

confidence: 99%

“…(Given that spacing below 60 nm promotes and stabilizes FA formation, we recently determined that RGD ligand spacing modulates β3 integrin activation and force transmission 23 . Here, we combine tunable ligand spacing by surface patterning with the immobilization of α5β1 or αvβ3 integrin selective ligands, 16 to show that α5β1 integrin clustering enhances cell spreading, and is dependent on ligand spacing: only at spacings below 60 nm, mature FAs are formed. Furthermore, αvβ3 integrin clustering is essential to this process.…”

Section: Introductionmentioning

confidence: 97%

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Selective binding and lateral clustering ofα5β1 andαvβ3 integrins: Unraveling the spatial requirements for cell spreading and focal adhesion assembly

Schaufler

Czichos-Medda

Hirschfeld-Warnecken

et al. 2016

Cell Adhesion & Migration

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Coordination of the specific functions of α5β1 and αvβ3 integrins is crucial for the precise regulation of cell adhesion, spreading and migration, yet the contribution of differential integrin-specific crosstalk to these processes remains unclear. To determine the specific functions of αvβ3 and α5β1 integrins, we used nanoarrays of gold particles presenting immobilized, integrin-selective peptidomimetic ligands. Integrin binding to the peptidomimetics is highly selective, and cells can spread on both ligands. However, spreading is faster and the projected cell area is greater on α5β1 ligand; both depend on ligand spacing. Quantitative analysis of adhesion plaques shows that focal adhesion size is increased in cells adhering to αvβ3 ligand at 30 and 60 nm spacings. Analysis of αvβ3 and α5β1 integrin clusters indicates that fibrillar adhesions are more prominent in cells adhering to α5β1 ligand, while clusters are mostly localized at the cell margins in cells adhering to αvβ3 ligand. αvβ3 integrin clusters are more pronounced on αvβ3 ligand, though they can also be detected in cells adhering to α5β1 ligand. Furthermore, α5β1 integrin clusters are present in cells adhering to α5β1 ligand, and often colocalize with αvβ3 clusters. Taken together, these findings indicate that the activation of αvβ3 integrin by ligand binding is dispensable for initial adhesion and spreading, but essential to formation of stable focal adhesions.

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“…In view of these prospects, an 18 F-labeled cyclic peptide with high affinity for a 5 b 1 integrin was developed but, despite encouraging in vitro data, proved unsuitable for in vivo PET imaging (27). Some acyclic pseudopeptides for selective targeting of integrins a v b 3 and a 5 b 1 were reported even earlier (28,29). Although the corresponding 68 Ga-labeled compounds allowed the visualization of expression of both integrins in tumorxenografted mice (30), they showed a considerable amount of unspecific uptake in organs, essentially rendering them less suitable for clinical application.…”

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Complementary, Selective PET Imaging of Integrin Subtypes α₅β₁ and α_vβ₃ Using ⁶⁸Ga-Aquibeprin and ⁶⁸Ga-Avebetrin

et al. 2015

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Despite in vivo mapping of integrin α v β 3 expression being thoroughly investigated in recent years, its clinical value is still not well defined. For imaging of angiogenesis, the integrin subtype α 5 β 1 appears to be a promising target, for which purpose we designed the PET radiopharmaceutical 68 Ga-aquibeprin. Methods: 68 Ga-aquibeprin was obtained by click-chemistry (CuAAC) trimerization of a α 5 β 1 integrin-binding pseudopeptide on the triazacyclononane-triphosphinate (TRAP) chelator, followed by automated 68 Ga labeling. Integrin α 5 β 1 and α v β 3 affinities were determined in enzyme linked immune sorbent assay on immobilized integrins, using fibronectin and vitronectin, respectively, as competitors. M21 (human melanoma)-bearing severe combined immunodeficient mice were used for biodistribution, PET imaging, and determination of in vivo metabolization. The expression of α 5 and β 3 subunits was determined by immunohistochemistry on paraffin sections of M21 tumors. Results: 68 Ga-aquibeprin shows high selectivity for integrin α 5 β 1 (50% inhibition concentration [IC 50 ] 5 0.088 nM) over α v β 3 (IC 50 5 620 nM) and a pronounced hydrophilicity (log D 5 -4.2). Severe combined immunodeficient mice xenografted with M21 human melanoma were found suitable for in vivo evaluation, as M21 immunohistochemistry showed not only an endothelial and strong cytoplasmatic expression of the β 3 integrin subunit but also an intense expression of the α 5 integrin subunit particularly in the endothelial cells of intratumoral small vessels. Ex vivo biodistribution (90 min after injection) showed high uptake in M21 tumor (2.42 ± 0.21 percentage injected dose per gram), fast renal excretion, and low background; tumor-to-blood and tumor-to-muscle ratios were 10.6 ± 2.5 and 20.9 ± 2.4, respectively. 68 Ga-aquibeprin is stable in vivo; no metabolites were detected in mouse urine, blood serum, kidney, and liver homogenates 30 min after injection. PET imaging was performed for 68 Ga-aquibeprin and the previously described, structurally related c(RGDfK) trimer 68 Ga-avebetrin, which shows an inverse selectivity for integrin α v β 3 (IC 50 5 0.22 nM) over α 5 β 1 (IC 50 5 39 nM). In vivo target specificity was proven by cross-competition studies; tumor uptake of either tracer was not affected by the coadministration of 40 nmol (∼5 mg/kg) of the respective other compound. Conclusion: 68 Ga-aquibeprin and 68 Ga-avebetrin are recommendable for complementary mapping of integrins α 5 β 1 and α v β 3 by PET, allowing for future studies on the role of these integrins in angiogenesis, tumor progression, metastasis, and myocardial infarct healing.

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Functionalizing αvβ3‐ or α5β1‐Selective Integrin Antagonists for Surface Coating: A Method To Discriminate Integrin Subtypes In Vitro

Cited by 83 publications

References 46 publications

Pharmacophoric Modifications Lead to Superpotent αvβ3 Integrin Ligands with Suppressed α5β1 Activity

Pharmacophoric Modifications Lead to Superpotent αvβ3 Integrin Ligands with Suppressed α5β1 Activity

Selective binding and lateral clustering ofα5β1 andαvβ3 integrins: Unraveling the spatial requirements for cell spreading and focal adhesion assembly

Complementary, Selective PET Imaging of Integrin Subtypes α₅β₁ and α_vβ₃ Using ⁶⁸Ga-Aquibeprin and ⁶⁸Ga-Avebetrin

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Functionalizing αvβ3‐ or α5β1‐Selective Integrin Antagonists for Surface Coating: A Method To Discriminate Integrin Subtypes In Vitro

Cited by 83 publications

References 46 publications

Pharmacophoric Modifications Lead to Superpotent αvβ3 Integrin Ligands with Suppressed α5β1 Activity

Pharmacophoric Modifications Lead to Superpotent αvβ3 Integrin Ligands with Suppressed α5β1 Activity

Selective binding and lateral clustering ofα5β1 andαvβ3 integrins: Unraveling the spatial requirements for cell spreading and focal adhesion assembly

Complementary, Selective PET Imaging of Integrin Subtypes α5β1 and αvβ3 Using 68Ga-Aquibeprin and 68Ga-Avebetrin

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Complementary, Selective PET Imaging of Integrin Subtypes α₅β₁ and α_vβ₃ Using ⁶⁸Ga-Aquibeprin and ⁶⁸Ga-Avebetrin