title: Oxidized antithrombin is a dual inhibitor of coagulation and angiogenesis: Importance of low heparin affinity.
abstract: Endogenous proteins that promote vascular endothelial cell based inhibition of angiogenesis are an attractive option for antitumor therapy. Inactive cleaved and latent conformations of antithrombin (AT) are antiangiogenic, but not its native form which is an inhibitor of proteases involved in blood coagulation. Unlike native, the cleaved and latent conformations are reactive center loop inserted conformations which binds heparin with very low affinity. We use a sulfoxy modified AT to assess the role of reactive center loop insertion and heparin affinity in antiangiogenic function. Chorioallantoic membrane assay (CAM) shows that antiangiogenic activity of latent and oxidized AT are better than thalidomide, a potent antiangiogenic drug. Wound healing experiments suggest that latent and oxidized conformations can influence endothelial cell migration. Latent and cleaved conformations of AT shows an increase in α-helical content in the presence of unfractionated heparin, but not the oxidized AT. Unlike the loop inserted polymer, cleaved and latent conformations, oxidized AT has factor Xa inhibitory activity indicating that loop insertion is not necessary for antiangiogenic role. The results of our study establish that active conformation of AT can become antiangiogenic while maintaining its anticoagulant activity possibly through chelation of low affinity heparin in the vicinity of endothelial cell.
authors.affiliation: Protein Conformation and Enzymology Lab, Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India.
authors.forename: Asim
authors.initials: A
authors.lastname: Azhar
authors.affiliation: Protein Conformation and Enzymology Lab, Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India.
authors.forename: Mohammad Sazzad
authors.initials: MS
authors.lastname: Khan
authors.affiliation: Vascular Biology Lab, AU-KBC Research Centre, Anna University, MIT Campus, Chennai, India.
authors.forename: Akila
authors.initials: A
authors.lastname: Swaminathan
authors.affiliation: Protein Conformation and Enzymology Lab, Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India.
authors.forename: Asma
authors.initials: A
authors.lastname: Naseem
authors.affiliation: Vascular Biology Lab, AU-KBC Research Centre, Anna University, MIT Campus, Chennai, India.
authors.forename: Suvro
authors.initials: S
authors.lastname: Chatterjee
authors.affiliation: Protein Conformation and Enzymology Lab, Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India. Electronic address: mjairajpuri@jmi.ac.in.
authors.forename: Mohamad Aman
authors.initials: MA
authors.lastname: Jairajpuri
mesh_terms: D020533:Angiogenesis Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D000991:Antithrombins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D015951:Factor Xa / Q000378:metabolism; D006493:Heparin / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D014945:Wound Healing / Q000187:drug effects
chemical_list: D020533:Angiogenesis Inhibitors; D000991:Antithrombins; D006493:Heparin; D015951:Factor Xa
keywords: Angiogenesis; Antithrombin; Coagulation; Endogenous antiangiogenic proteins; Heparin; Serpin; Tumor growth