Cyclic isoDGR and RGD peptidomimetics containing bifunctional diketopiperazine scaffolds are integrin antagonists.

The cyclo[DKP-isoDGR] peptidomimetics 2-5, containing bifunctional diketopiperazine (DKP) scaffolds that differ in the configuration of the two DKP stereocenters and in the substitution at the DKP nitrogen atoms, were prepared and examined in vitro in competitive binding assays with purified αv β3 and αv β5 integrin receptors. IC50 values ranged from low nanomolar (ligand 3) to submicromolar with αv β3 integrin. The biological activities of ligands cyclo[DKP3-RGD] 1 and cyclo[DKP3-isoDGR] 3, bearing the same bifunctional DKP scaffold and showing similar αV β3 integrin binding values, were compared in terms of their cellular effects in human U373 glioblastoma cells. Compounds 1 and 3 displayed overlapping inhibitory effects on the FAK/Akt integrin activated transduction pathway and on integrin-mediated cell infiltration processes, and qualify therefore, despite the different RGD and isoDGR sequences, as integrin antagonists. Both compounds induced apoptosis in glioma cells after 72 hour treatment.

[1]  Marian Brennan,et al.  Integrins as therapeutic targets: lessons and opportunities , 2010, Nature Reviews Drug Discovery.

[2]  L. Belvisi,et al.  Synthesis and biological evaluation (in vitro and in vivo) of cyclic arginine-glycine-aspartate (RGD) peptidomimetic-paclitaxel conjugates targeting integrin αVβ3. , 2012, Journal of medicinal chemistry.

[3]  B. Garmy-Susini,et al.  Integrins in angiogenesis and lymphangiogenesis , 2008, Nature Reviews Cancer.

[4]  M. Civera,et al.  Cyclic isoDGR peptidomimetics as low-nanomolar αvβ3 integrin ligands. , 2013, Chemistry.

[5]  Laura Belvisi,et al.  Determination of the binding epitope of RGD-peptidomimetics to αvβ3 and α(IIb)β3 integrin-rich intact cells by NMR and computational studies. , 2013, Organic & biomolecular chemistry.

[6]  M. Civera,et al.  Synthesis and Conformational Studies of Peptidomimetics Containing a New Bifunctional Diketopiperazine Scaffold Acting as a β-Hairpin Inducer , 2008 .

[7]  C. Bokemeyer,et al.  Cilengitide induces cellular detachment and apoptosis in endothelial and glioma cells mediated by inhibition of FAK/src/AKT pathway , 2008, Journal of experimental & clinical cancer research : CR.

[8]  Silvia Mari,et al.  Molecular dynamics reveal that isoDGR-containing cyclopeptides are true αvβ3 antagonists unable to promote integrin allostery and activation. , 2012, Angewandte Chemie.

[9]  Li Zhang,et al.  Ligand Binding to Integrins* , 2000, The Journal of Biological Chemistry.

[10]  M. Serra,et al.  Small molecule integrin antagonists in cancer therapy. , 2009, Mini reviews in medicinal chemistry.

[11]  E. Novellino,et al.  Conformational control of integrin-subtype selectivity in isoDGR peptide motifs: a biological switch. , 2010, Angewandte Chemie.

[12]  R. Longhi,et al.  Spontaneous Formation of L-Isoaspartate and Gain of Function in Fibronectin* , 2006, Journal of Biological Chemistry.

[13]  R. Longhi,et al.  Isoaspartate-glycine-arginine: a new tumor vasculature-targeting motif. , 2008, Cancer research.

[14]  K. Aldape,et al.  Cilengitide combined with standard treatment for patients with newly diagnosed glioblastoma with methylated MGMT promoter (CENTRIC EORTC 26071-22072 study): a multicentre, randomised, open-label, phase 3 trial. , 2014, The Lancet. Oncology.

[15]  G. van der Pluijm,et al.  Targeting of Alpha-V Integrins Reduces Malignancy of Bladder Carcinoma , 2014, PloS one.

[16]  Horst Kessler,et al.  Cilengitide: The First Anti-Angiogenic Small Molecule Drug Candidate. Design, Synthesis and Clinical Evaluation , 2010, Anti-cancer agents in medicinal chemistry.

[17]  E. Novellino,et al.  Increasing αvβ3 selectivity of the anti-angiogenic drug cilengitide by N-methylation. , 2011, Angewandte Chemie.

[18]  Thilo Stehle,et al.  Crystal Structure of the Extracellular Segment of Integrin αVβ3 in Complex with an Arg-Gly-Asp Ligand , 2002, Science.

[19]  S. Clarke.  Propensity for spontaneous succinimide formation from aspartyl and asparaginyl residues in cellular proteins. , 2009, International journal of peptide and protein research.

[20]  G. Alghisi,et al.  The Integrin Antagonist Cilengitide Activates αVβ3, Disrupts VE-Cadherin Localization at Cell Junctions and Enhances Permeability in Endothelial Cells , 2009, PLoS ONE.

[21]  J. Norman,et al.  Stimulation of tumor growth and angiogenesis by low concentrations of RGD-mimetic integrin inhibitors , 2009, Nature Medicine.

[22]  H. Kessler,et al.  Erhöhung der αvβ3‐Selektivität des Angiogenese hemmenden Wirkstoffs Cilengitid durch N‐Methylierung , 2011 .

[23]  R. Longhi,et al.  Structural Basis for the Interaction of isoDGR with the RGD-binding Site of αvβ3 Integrin* , 2008, Journal of Biological Chemistry.

[24]  Richard O Hynes,et al.  Integrins Bidirectional, Allosteric Signaling Machines , 2002, Cell.

[25]  Susan Chang,et al.  Cilengitide in patients with recurrent glioblastoma: the results of NABTC 03-02, a phase II trial with measures of treatment delivery , 2011, Journal of Neuro-Oncology.

[26]  C. Pedone,et al.  Peptide‐based Molecules in Angiogenesis , 2006, Chemical biology & drug design.

[27]  R. Longhi,et al.  Critical Role of Flanking Residues in NGR-to-isoDGR Transition and CD13/Integrin Receptor Switching* , 2010, The Journal of Biological Chemistry.

[28]  M. Serra,et al.  A small-molecule RGD-integrin antagonist inhibits cell adhesion, cell migration and induces anoikis in glioblastoma cells , 2012, International journal of oncology.

[29]  David A. Cheresh,et al.  Integrins in cancer: biological implications and therapeutic opportunities , 2010, Nature Reviews Cancer.

[30]  A. Corti,et al.  Isoaspartate-dependent molecular switches for integrin–ligand recognition , 2011, Journal of Cell Science.

[31]  R. Fanelli,et al.  Effects of a novel cyclic RGD peptidomimetic on cell proliferation, migration and angiogenic activity in human endothelial cells , 2014, Vascular cell.

[32]  H. Kessler,et al.  Konformative Kontrolle über Integrin-Subtyp-Selektivitäten in isoDGR-Peptidmotiven: ein biologischer Schalter† , 2010 .

[33]  I. Shiojima,et al.  Role of Akt Signaling in Vascular Homeostasis and Angiogenesis , 2002, Circulation research.

[34]  Laura Belvisi,et al.  Cyclic RGD peptidomimetics containing bifunctional diketopiperazine scaffolds as new potent integrin ligands. , 2009, Chemistry.

[35]  A. Spitaleri,et al.  Use of metadynamics in the design of isoDGR-based αvβ3 antagonists to fine-tune the conformational ensemble. , 2011, Angewandte Chemie.

[36]  C. Curti,et al.  Targeting αvβ3 Integrin: Design and Applications of Mono- and Multifunctional RGD-Based Peptides and Semipeptides , 2010 .

[37]  R. Colombo,et al.  Selective O-acylation of unprotected N-benzylserine methyl ester and O,N-acyl transfer in the formation of cyclo[Asp-Ser] diketopiperazines , 2010 .

[38]  D. Schlaepfer,et al.  FAK in cancer: mechanistic findings and clinical applications , 2014, Nature Reviews Cancer.