title: Neuroblastoma angiogenesis is inhibited with a folded synthetic molecule corresponding to the epidermal growth factor-like module of the follistatin domain of SPARC.
abstract: Secreted protein acidic and rich in cysteine (SPARC) is a multifunctional matricellular glycoprotein. In vitro, SPARC inhibits the proliferation and migration of endothelial cells stimulated by growth factors and induces endothelial cell apoptosis. We previously showed that SPARC also inhibits angiogenesis in vivo and impairs the growth of the pediatric tumor neuroblastoma (NB). SPARC comprises three domains that are independently folded by a complex pattern of disulfide bonds and have a high degree of structural conservation. In this study, separate modules of the SPARC domains were synthesized as cysteine-linked peptides and tested for their ability to inhibit angiogenesis. Peptide FS-E, representing the epidermal growth factor (EGF)-like module of the follistatin (FS) domain, did not cause endothelial cell apoptosis but strongly inhibited basic fibroblast growth factor (bFGF)-induced endothelial cell migration with an ED(50) = 10 pmol/L. In vivo, peptide FS-E blocked bFGF-stimulated angiogenesis and neovascularization induced by NB cells. The EGF-like conformation was essential for peptide FS-E function because reduction of its two disulfide bonds completely abrogated peptide activity. Peptides FS-K and EC-N, corresponding to part of the Kazal module of the FS domain and the conserved alpha-helix in the extracellular calcium-binding domain, respectively, had minimal to no inhibitory activity. Our data show that the EGF-like module of the SPARC FS domain is angiosuppressive, and its structural conformation is critical for antiangiogenic activity.
authors.affiliation: The Robert H. Lurie Comprehensive Cancer Center and Department of Pediatrics, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chlenski
authors.forename: Shuqing
authors.initials: S
authors.lastname: Liu
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Baker
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Yang
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Tian
authors.forename: Helen R
authors.initials: HR
authors.lastname: Salwen
authors.forename: Susan L
authors.initials: SL
authors.lastname: Cohn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D017124:Conserved Sequence; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D009447:Neuroblastoma / Q000098:blood supply*; D015676:Osteonectin / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D017510:Protein Folding; D017434:Protein Structure, Tertiary
chemical_list: D015676:Osteonectin; D010446:Peptide Fragments; D004815:Epidermal Growth Factor