title: A peptide corresponding to the C-terminal region of pleiotrophin inhibits angiogenesis in vivo and in vitro.
abstract: Pleiotrophin (PTN) is a heparin-binding growth factor that plays a significant role in tumor growth and angiogenesis. We have previously shown that in order for PTN to induce migration of endothelial cells, binding to both α(ν) β(3) integrin and its receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ) is required. In the present study we show that a synthetic peptide corresponding to the last 25 amino acids of the C-terminal region of PTN (PTN(112-136) ) inhibited angiogenesis in the in vivo chicken embryo chorioallantoic membrane (CAM) assay and PTN-induced migration and tube formation of human endothelial cells in vitro. PTN(112-136) inhibited binding of PTN to α(ν) β(3) integrin, and as shown by surface plasmon resonance (SPR) measurements, specifically interacted with the specificity loop of the extracellular domain of β(3) . Moreover, it abolished PTN-induced FAK Y397 phosphorylation, similarly to the effect of a neutralizing α(ν) β(3) -selective antibody. PTN(112-136) did not affect binding of PTN to RPTPβ/ζ in endothelial cells and induced β(3) Y773 phosphorylation and ERK1/2 activation to a similar extent with PTN. This effect was inhibited by down-regulation of RPTPβ/ζ by siRNA or by c-src inhibition, suggesting that PTN(112-136) may interact with RPTPβ/ζ. NMR spectroscopy studies showed that PTN(112-136) was characterized by conformational flexibility and absence of any element of secondary structure at room temperature, although the biologically active peptide segment 123-132 may adopt a defined structure at lower temperature. Collectively, our data suggest that although PTN(112-136) induces some of the signaling pathways triggered by PTN, it inhibits PTN-induced angiogenic activities through inhibition of PTN binding to α(ν) β(3) integrin.
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Patras 26504, Greece.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Mikelis
authors.forename: Margarita
authors.initials: M
authors.lastname: Lamprou
authors.forename: Marina
authors.initials: M
authors.lastname: Koutsioumpa
authors.forename: Alexandros G
authors.initials: AG
authors.lastname: Koutsioubas
authors.forename: Zinovia
authors.initials: Z
authors.lastname: Spyranti
authors.forename: Aikaterini A
authors.initials: AA
authors.lastname: Zompra
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Spiliopoulos
authors.forename: Alexandros A
authors.initials: AA
authors.lastname: Vradis
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Katsoris
authors.forename: Georgios A
authors.initials: GA
authors.lastname: Spyroulias
authors.forename: Paul
authors.initials: P
authors.lastname: Cordopatis
authors.forename: Jose
authors.initials: J
authors.lastname: Courty
authors.forename: Evangelia
authors.initials: E
authors.lastname: Papadimitriou
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D016207:Cytokines / Q000737:chemistry* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D047468:Immunoprecipitation; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D034622:RNA Interference; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5 / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; D039302:Integrin alphaVbeta3; D010455:Peptides; C066845:pleiotrophin; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5