title: Isthmin is a novel secreted angiogenesis inhibitor that inhibits tumour growth in mice.
abstract: Anti-angiogenesis represents a promising therapeutic strategy for the treatment of various malignancies. Isthmin (ISM) is a gene highly expressed in the isthmus of the midbrain-hindbrain organizer in Xenopus with no known functions. It encodes a secreted 60 kD protein containing a thrombospondin type 1 repeat domain in the central region and an adhesion-associated domain in MUC4 and other proteins (AMOP) domain at the C-terminal. In this work, we demonstrate that ISM is a novel angiogenesis inhibitor. Recombinant mouse ISM inhibited endothelial cell (EC) capillary network formation on Matrigel through its C-terminal AMOP domain. It also suppressed vascular endothelial growth factor (VEGF)-basic fibroblast growth factor (bFGF) induced in vivo angiogenesis in mouse. It mitigated VEGF-stimulated EC proliferation without affecting EC migration. Furthermore, ISM induced EC apoptosis in the presence of VEGF through a caspase-dependent pathway. ISM binds to αvβ(5) integrin on EC surface and supports EC adhesion. Overexpression of ISM significantly suppressed mouse B16 melanoma tumour growth through inhibition of tumour angiogenesis without affecting tumour cell proliferation. Knockdown of isthmin in zebrafish embryos using morpholino antisense oligonucleotides led to disorganized intersegmental vessels in the trunk. Our results demonstrate that ISM is a novel endogenous angiogenesis inhibitor with functions likely in physiological as well as pathological angiogenesis.
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore.
authors.forename: Wei
authors.initials: W
authors.lastname: Xiang
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Ke
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Grace Ho-Yuet
authors.initials: GH
authors.lastname: Cheng
authors.forename: Ishak Darryl
authors.initials: ID
authors.lastname: Irwan
authors.forename: K N
authors.initials: KN
authors.lastname: Sulochana
authors.forename: Padma
authors.initials: P
authors.lastname: Potturi
authors.forename: Zhengyuan
authors.initials: Z
authors.lastname: Wang
authors.forename: He
authors.initials: H
authors.lastname: Yang
authors.forename: Jingyu
authors.initials: J
authors.lastname: Wang
authors.forename: Lang
authors.initials: L
authors.lastname: Zhuo
authors.forename: R Manjunatha
authors.initials: RM
authors.lastname: Kini
authors.forename: Ruowen
authors.initials: R
authors.lastname: Ge
mesh_terms: D000595:Amino Acid Sequence; D020533:Angiogenesis Inhibitors / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation; D003001:Cloning, Molecular; D016222:Fibroblast Growth Factor 2 / Q000037:antagonists & inhibitors; D006801:Humans; D016023:Integrins / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D008546:Melanoma, Experimental / Q000098:blood supply / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008969:Molecular Sequence Data; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D018919:Neovascularization, Physiologic; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D014183:Transplantation, Heterologous; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D020533:Angiogenesis Inhibitors; D016023:Integrins; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; D029961:Zebrafish Proteins; C571341:ism1 protein, zebrafish; C571340:isthmin protein, mouse; D016222:Fibroblast Growth Factor 2