Abstract
Tumstatin is an angiogenesis inhibitor that binds to alphavbeta3 integrin and suppresses tumor growth. Previous deletion mutagenesis studies identified a 25-aa fragment of tumstatin (tumstatin peptide) with in vitro antiangiogenic activity. Here, we demonstrate that systemic administration of this tumstatin peptide inhibits tumor growth and angiogenesis. Site-directed mutagenesis identified amino acids L, V, and D as essential for the antiangiogenic activity of tumstatin. The tumstatin peptide binds to alphavbeta3 integrin on proliferating endothelial cells and localizes to select tumor endothelium in vivo. Using 3D molecular modeling, we identify a putative interaction interface for tumstatin peptide on alphavbeta3 integrin. The antitumor activity of the tumstatin peptide, in combination with bevacizumab (anti-VEGF antibody), displays significant improvement in efficacy against human renal cell carcinoma xenografts when compared with the single-agent use. Collectively, our results demonstrate that tumstatin peptide binds specifically to the tumor endothelium, and its antiangiogenic action is mediated by alphavbeta3 integrin, and, in combination with an anti-VEGF antibody it exhibits enhanced tumor suppression of renal cell carcinoma.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Substitution / genetics
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Angiogenesis Inhibitors / genetics
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Angiogenesis Inhibitors / metabolism
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Angiogenesis Inhibitors / pharmacology*
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Angiogenesis Inhibitors / therapeutic use
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Animals
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Antibodies, Monoclonal / pharmacology
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Antibodies, Monoclonal / therapeutic use
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Antibodies, Monoclonal, Humanized
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Antineoplastic Combined Chemotherapy Protocols
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Aspartic Acid / genetics
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Aspartic Acid / metabolism
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Autoantigens / genetics
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Autoantigens / metabolism
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Autoantigens / pharmacology*
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Autoantigens / therapeutic use
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Bevacizumab
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Carcinoma, Renal Cell / blood supply
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Carcinoma, Renal Cell / drug therapy*
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Cell Proliferation
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Cells, Cultured
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Collagen Type IV / genetics
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Collagen Type IV / metabolism
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Collagen Type IV / pharmacology*
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Collagen Type IV / therapeutic use
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Endothelial Cells / drug effects
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Endothelial Cells / metabolism
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Humans
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Integrin alphaVbeta3 / metabolism
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Kidney Neoplasms / blood supply
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Kidney Neoplasms / drug therapy*
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Leucine / genetics
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Leucine / metabolism
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Mice
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Mice, Inbred C57BL
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Mutagenesis, Site-Directed
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Neoplasm Transplantation
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Neovascularization, Pathologic / drug therapy*
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Protein Conformation
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Valine / genetics
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Valine / metabolism
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Xenograft Model Antitumor Assays
Substances
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Angiogenesis Inhibitors
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Antibodies, Monoclonal
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Antibodies, Monoclonal, Humanized
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Autoantigens
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Collagen Type IV
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Integrin alphaVbeta3
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type IV collagen alpha3 chain
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Bevacizumab
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Aspartic Acid
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Leucine
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Valine