title: NG2 proteoglycan as a pericyte target for anticancer therapy by tumor vessel infarction with retargeted tissue factor.
abstract: tTF-TAA and tTF-LTL are fusion proteins consisting of the extracellular domain of tissue factor (TF) and the peptides TAASGVRSMH and LTLRWVGLMS, respectively. These peptides represent ligands of NG2, a surface proteoglycan expressed on angiogenic pericytes and some tumor cells. Here we have expressed the model compound tTF-NGR, tTF-TAA, and tTF-LTL with different lengths in the TF domain in E. coli and used these fusion proteins for functional studies in anticancer therapy. We aimed to retarget TF to tumor vessels leading to tumor vessel infarction with two barriers of selectivity, a) the leaky endothelial lining in tumor vessels with the target NG2 being expressed on pericytes on the abluminal side of the endothelial cell barrier and b) the preferential expression of NG2 on angiogenic vessels such as in tumors. Chromatography-purified tTF-TAA showed identical Factor X (FX)-activating procoagulatory activity as the model compound tTF-NGR with Km values of approx. 0.15 nM in Michaelis-Menten kinetics. The procoagulatory activity of tTF-LTL varied with the chosen length of the TF part of the fusion protein. Flow cytometry revealed specific binding of tTF-TAA to NG2-expressing pericytes and tumor cells with low affinity and dissociation KD in the high nM range. In vivo and ex vivo fluorescence imaging of tumor xenograft-carrying animals and of the explanted tumors showed reduction of tumor blood flow upon tTF-TAA application. Therapeutic experiments showed a reproducible antitumor activity of tTF-TAA against NG2-expressing A549-tumor xenografts, however, with a rather small therapeutic window (active/toxic dose in mg/kg body weight).
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Caroline
authors.initials: C
authors.lastname: Brand
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schliemann
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Ring
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Kessler
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Bäumer
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Linus
authors.initials: L
authors.lastname: Angenendt
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Mantke
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Ross
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Hintelmann
authors.affiliation: Gerhard-Domagk Institute for Pathology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Tilmann
authors.initials: T
authors.lastname: Spieker
authors.affiliation: Gerhard-Domagk Institute for Pathology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Wardelmann
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Rolf M
authors.initials: RM
authors.lastname: Mesters
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Wolfgang E
authors.initials: WE
authors.lastname: Berdel
authors.affiliation: Department of Medicine A, Hematology, Oncology and Pneumology, University of Muenster, Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schwöppe
mesh_terms: D000818:Animals; D000941:Antigens / Q000096:biosynthesis / Q000378:metabolism*; D045744:Cell Line, Tumor; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D058990:Molecular Targeted Therapy; D009369:Neoplasms / Q000098:blood supply* / Q000188:drug therapy*; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology*; D020286:Pericytes / Q000187:drug effects / Q000378:metabolism; D011509:Proteoglycans / Q000096:biosynthesis / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D013925:Thromboplastin / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D000941:Antigens; D009842:Oligopeptides; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins; D013925:Thromboplastin; D000099216:Chondroitin Sulfate Proteoglycan 4
keywords: NG2 proteoglycan; cancer; truncated tissue factor; vascular infarction; vascular targeting