title: The mechanism of cancer-mediated conversion of plasminogen to the angiogenesis inhibitor angiostatin.
abstract: Angiostatin, a potent naturally occurring inhibitor of angiogenesis and growth of tumor metastases, is generated by cancer-mediated proteolysis of plasminogen. Human prostate carcinoma cells (PC-3) release enzymatic activity that converts plasminogen to angiostatin. We have now identified two components released by PC-3 cells, urokinase (uPA) and free sulfhydryl donors (FSDs), that are sufficient for angiostatin generation. Furthermore, in a defined cell-free system, plasminogen activators [uPA, tissue-type plasminogen activator (tPA), or streptokinase], in combination with one of a series of FSDs (N-acetyl-L-cysteine, D-penicillamine, captopril, L-cysteine, or reduced glutathione] generate angiostatin from plasminogen. An essential role of plasmin catalytic activity for angiostatin generation was identified by using recombinant mutant plasminogens as substrates. The wild-type recombinant plasminogen was converted to angiostatin in the setting of uPA/FSD; however, a plasminogen activation site mutant and a catalytically inactive mutant failed to generate angiostatin. Cell-free derived angiostatin inhibited angiogenesis in vitro and in vivo and suppressed the growth of Lewis lung carcinoma metastases. These findings define a direct mechanism for cancer-cell-mediated angiostatin generation and permit large-scale production of bioactive angiostatin for investigation and potential therapeutic application.
authors.affiliation: Department of Medicine, Division of Hematology/Oncology, Northwestern University School of Medicine, Chicago, IL 60611, USA.
authors.forename: S
authors.initials: S
authors.lastname: Gately
authors.forename: P
authors.initials: P
authors.lastname: Twardowski
authors.forename: M S
authors.initials: MS
authors.lastname: Stack
authors.forename: D L
authors.initials: DL
authors.lastname: Cundiff
authors.forename: D
authors.initials: D
authors.lastname: Grella
authors.forename: F J
authors.initials: FJ
authors.lastname: Castellino
authors.forename: J
authors.initials: J
authors.lastname: Enghild
authors.forename: H C
authors.initials: HC
authors.lastname: Kwaan
authors.forename: F
authors.initials: F
authors.lastname: Lee
authors.forename: R A
authors.initials: RA
authors.lastname: Kramer
authors.forename: O
authors.initials: O
authors.lastname: Volpert
authors.forename: N
authors.initials: N
authors.lastname: Bouck
authors.forename: G A
authors.initials: GA
authors.lastname: Soff
mesh_terms: D043168:Angiostatins; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism*; D018827:Carcinoma, Lewis Lung / Q000378:metabolism / Q000473:pathology; D002474:Cell-Free System; D002846:Chromatography, Affinity; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D010446:Peptide Fragments / Q000096:biosynthesis* / Q000302:isolation & purification; D010958:Plasminogen / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D010446:Peptide Fragments; D043168:Angiostatins; D010958:Plasminogen