title: Design, synthesis and characterization of novel small molecular inhibitors of ephrin-B2 binding to EphB4.
abstract: EphB4 is a member of the large Eph receptor tyrosine kinase family. By interacting with its preferred ligand ephrin-B2, which is also a transmembrane protein, EphB4 plays a role in a variety of physiological and pathological processes ranging from bone remodeling to cancer malignancy. EphB4-ephrin-B2 binding occurs at sites of contact between cells. Ephrin-B2 causes EphB4 clustering and increased kinase activity to generate downstream signals that affect cell behavior. Previous work identified a high-affinity antagonistic peptide that targets EphB4, named TNYL-RAW. This peptide is 15 amino acid long, has a molecular weight of ~1700 Da and binds to the ephrin-binding pocket of EphB4. Here we report the structure-based design and chemical synthesis of two novel small molecules of ~600-700 Da, which were designed starting from the small and functionally critical C-terminal portion of the TNYL-RAW peptide. These compounds inhibit ephrin-B2 binding to EphB4 at low micromolar concentrations. Additionally, although the ephrin-B2 ligand can interacts with multiple other Eph receptors besides EphB4, the two compounds retain the high selectivity of the TNYL-RAW peptide in targeting EphB4. TNYL-RAW peptide displacement experiments using the more potent of the two compounds, compound 5, suggest a competitive mode of inhibition. These EphB4 antagonistic compounds can serve as promising templates for the further development of small molecule drugs targeting EphB4.
authors.affiliation: SUNY Upstate Cancer Research Institute, Department of Pharmacology, State University of New York, Syracuse, NY 13210, USA.
authors.forename: Srinivas
authors.initials: S
authors.lastname: Duggineni
authors.forename: Sayantan
authors.initials: S
authors.lastname: Mitra
authors.forename: Roberta
authors.initials: R
authors.lastname: Noberini
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Han
authors.forename: Nan
authors.initials: N
authors.lastname: Lin
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.forename: Wang
authors.initials: W
authors.lastname: Tian
authors.forename: Jing
authors.initials: J
authors.lastname: An
authors.forename: Elena B
authors.initials: EB
authors.lastname: Pasquale
authors.forename: Ziwei
authors.initials: Z
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology*; D003198:Computer Simulation; D015195:Drug Design; D036388:Ephrin-B2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D036224:Receptor, EphB4 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D000970:Antineoplastic Agents; D036388:Ephrin-B2; D036224:Receptor, EphB4