title: Anastellin, the angiostatic fibronectin peptide, is a selective inhibitor of lysophospholipid signaling.
abstract: Angiogenesis is regulated by integrin-dependent cell adhesion and the activation of specific cell surface receptors on vascular endothelial cells by angiogenic factors. Lysophosphatidic acid (LPA) and sphingosine-1 phosphate (S1P) are bioactive lysophospholipids that activate G protein-coupled receptors that stimulate phosphatidylinositol 3-kinase (PI3K), Ras, and Rho effector pathways involved in vascular cell survival, proliferation, adhesion, and migration. Previous studies have shown that anastellin, a fragment of the first type III module of fibronectin, functions as an antiangiogenic peptide suppressing tumor growth and metastasis. We have previously shown that anastellin blocks serum-dependent proliferation of microvessel endothelial cells (MVEC) by affecting extracellular signal-regulated kinase (ERK)-dependent G(1)-S transition. However, the mechanism by which anastellin regulates endothelial cell function remains unclear. In the present study, we mapped several lysophospholipid-mediated signaling pathways in MVEC and examined the effects of anastellin on LPA- and S1P-induced MVEC proliferation, migration, and cytoskeletal organization. Both LPA and S1P activated PI3K, Ras/ERK, and Rho/Rho kinase pathways, leading to migration, G(1)-S cell cycle progression, and stress fiber formation, respectively. Stimulation of proliferation by LPA/S1P occurred through a G(i)-dependent Ras/ERK pathway, which was independent of growth factor receptors and PI3K and Rho/Rho kinase signaling. Although LPA and S1P activated both PI3K/Akt and Ras/ERK signaling through G(i), anastellin inhibited only the Ras/ERK pathway. Stress fiber formation in response to LPA was dependent on Rho/Rho kinase but independent of G(i) and unaffected by anastellin. These results suggest that lysophospholipid mediators of G(i) activation leading to PI3K/Akt and Ras/ERK signaling bifurcate downstream of G(i) and that anastellin selectively inhibits the Ras/ERK arm of the pathway.
authors.affiliation: Center for Cell Biology and Cancer Research (MC-165), Albany Medical College, Albany, NY 12208, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Ambesi
authors.forename: Paula J
authors.initials: PJ
authors.lastname: McKeown-Longo
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D043165:Angiostatic Proteins / Q000494:pharmacology*; D002465:Cell Movement; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005353:Fibronectins / Q000494:pharmacology*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008246:Lysophospholipids / Q000037:antagonists & inhibitors*; D008833:Microcirculation / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D012867:Skin / Q000098:blood supply; D054460:rho-Associated Kinases / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D043165:Angiostatic Proteins; D005353:Fibronectins; D008246:Lysophospholipids; D010446:Peptide Fragments; D043562:Receptors, G-Protein-Coupled; C423921:anastellin; D019869:Phosphatidylinositol 3-Kinases; D066246:ErbB Receptors; D040262:Receptors, Vascular Endothelial Growth Factor; D051057:Proto-Oncogene Proteins c-akt; D054460:rho-Associated Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go