title: Biological and molecular properties of a new alpha(v)beta3/alpha(v)beta5 integrin antagonist.
abstract: The aim of the present study was to identify specific alpha(v)beta3/alpha(v)beta5 integrin antagonists active on tumor-induced angiogenesis. To this purpose, in vitro integrin-binding assays were used to screen a library of conformationally constrained bicyclic lactam Arg-Gly-Asp-containing pseudopeptides. The results identified ST1646 as a high-affinity specific ligand for alpha(v)beta3 and alpha(v)beta5 integrins with negligible interacting with alpha5beta1 integrin. In all the assays, ST1646 was equipotent to or more potent than the well-characterized integrin antagonists c(RGDfV) and cyclo(Arg-Gly-Asp-d-Phe-[NMe]Val) (EMD121974). In the chorioallantoic membrane assay, topical administration of ST1646 was able to prevent the angiogenic responses elicited by recombinant fibroblast growth factor-2 or vascular endothelial growth factor. In addition, systemic administration of ST1646 in mice exerted a significant antiangiogenic activity on neovascularization triggered by mammary carcinoma MDA-MB435 cells implanted s.c. in a dorsal air sac via a (Millipore Filter Corporation, Bedford, MA) chamber. Moreover, ST1646 delivery via an osmotic pump inhibited the growth and vascularization of tumor xenografts originating from the injection of alpha(v)beta3/alpha(v)beta5-expressing human ovarian carcinoma cells in nude mice. In agreement with the biochemical and pharmacologic studies, Monte Carlo/Stochastic Dynamics simulation showed that the bicyclic scaffold in ST1646 forced the compound to assume a preferred conformation superimposable to the X-ray conformation of alpha(v)beta3-bound EMD121974. Accordingly, computer-docking studies indicated that the ST1646-alpha(v)beta3 integrin complex maintains the ligand-receptor distances and interactions observed in the crystalline EMD121974-alpha(v)beta3 integrin complex. Taken together, these observations indicate that ST1646 represents a dual alpha(v)beta3/alpha(v)beta5 integrin antagonist with interesting biochemical and biological features to be tested in cancer therapy.
authors.affiliation: Organic and Industrial Chemistry Department, Centre for Biomolecular Interdisciplinary Studies and Industrial Applications, University of Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Belvisi
authors.forename: Teresa
authors.initials: T
authors.lastname: Riccioni
authors.forename: Marcella
authors.initials: M
authors.lastname: Marcellini
authors.forename: Loredana
authors.initials: L
authors.lastname: Vesci
authors.forename: Ilaria
authors.initials: I
authors.lastname: Chiarucci
authors.forename: Daniela
authors.initials: D
authors.lastname: Efrati
authors.forename: Donatella
authors.initials: D
authors.lastname: Potenza
authors.forename: Carlo
authors.initials: C
authors.lastname: Scolastico
authors.forename: Leonardo
authors.initials: L
authors.lastname: Manzoni
authors.forename: Katia
authors.initials: K
authors.lastname: Lombardo
authors.forename: M Antonietta
authors.initials: MA
authors.lastname: Stasi
authors.forename: Augusto
authors.initials: A
authors.lastname: Orlandi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ciucci
authors.forename: Beatrice
authors.initials: B
authors.lastname: Nico
authors.forename: Domenico
authors.initials: D
authors.lastname: Ribatti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Giannini
authors.forename: Marco
authors.initials: M
authors.lastname: Presta
authors.forename: Paolo
authors.initials: P
authors.lastname: Carminati
authors.forename: Claudio
authors.initials: C
authors.lastname: Pisano
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001120:Arginine / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry; D002417:Cattle; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002645:Chickens; D018360:Crystallography, X-Ray; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D005998:Glycine / Q000737:chemistry; D006168:Guinea Pigs; D006801:Humans; D020128:Inhibitory Concentration 50; D039302:Integrin alphaVbeta3 / Q000037:antagonists & inhibitors*; D016023:Integrins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008819:Mice, Nude; D008833:Microcirculation; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D009010:Monte Carlo Method; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D009842:Oligopeptides / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry / Q000494:pharmacology*; D010974:Platelet Aggregation; D011485:Protein Binding; D011487:Protein Conformation; D019030:Receptors, Vitronectin / Q000037:antagonists & inhibitors*; D011994:Recombinant Proteins / Q000737:chemistry; D013269:Stochastic Processes; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D019096:Vitronectin / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D039302:Integrin alphaVbeta3; D016023:Integrins; D008024:Ligands; D009842:Oligopeptides; D010456:Peptides, Cyclic; D019030:Receptors, Vitronectin; D011994:Recombinant Proteins; C507281:ST1646; D042461:Vascular Endothelial Growth Factor A; D019096:Vitronectin; C064660:integrin alphaVbeta5; D016222:Fibroblast Growth Factor 2; D001224:Aspartic Acid; C047981:arginyl-glycyl-aspartic acid; D001120:Arginine; D005998:Glycine