title: Mast cell-derived angiopoietin-1 plays a critical role in the growth of plasma cell tumors.
abstract: Multiple myeloma in humans is frequently associated with mast cell infiltration and neovascularization, which correlate directly with disease severity, but the mechanisms underlying this relationship remain unclear. Here, we report that primary murine mast cells express angiopoietin-1 (Ang-1) and low levels of VEGF-A but not Ang-2 and that 2 established murine plasmacytoma cell lines express high levels of VEGF-A but little or no Ang-1 or Ang-2. An in vivo angiogenesis assay using extracellular matrix components shows that mast cells and plasmacytoma cells, together, promote marked neovascularization composed of dilated vessels, which is prevented by neutralization of VEGF-A and Ang-1 but is only partially reduced by neutralization of either VEGF-A or Ang-1. Mast cells within extracellular matrix components express Ang-1, and recombinant Ang-1 together with plasmacytoma cells promotes extracellular matrix neovascularization similar to that induced by mast cells. A transplantation assay shows that primary mast cells accelerate tumor growth by established plasmacytoma cell lines and that neutralization of Ang-1 alone or with VEGF-A reduces significantly the growth of plasmacytomas containing mast cells. These results demonstrate that mast cell-derived Ang-1 promotes the growth of plasmacytomas by stimulating neovascularization and provide further evidence supporting a causal relationship between inflammation and tumor growth.
authors.affiliation: Experimental Transplantation and Immunology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakayama
authors.forename: Lei
authors.initials: L
authors.lastname: Yao
authors.forename: Giovanna
authors.initials: G
authors.lastname: Tosato
mesh_terms: D042683:Angiopoietin-1 / Q000378:metabolism / Q000502:physiology*; D042702:Angiopoietin-2 / Q000096:biosynthesis; D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D003094:Collagen / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004338:Drug Combinations; D005109:Extracellular Matrix; D005260:Female; D007150:Immunohistochemistry; D007249:Inflammation; D007797:Laminin / Q000494:pharmacology; D008407:Mast Cells / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009101:Multiple Myeloma / Q000473:pathology; D009389:Neovascularization, Pathologic; D010954:Plasmacytoma / Q000378:metabolism*; D011509:Proteoglycans / Q000494:pharmacology; D012313:RNA / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
chemical_list: D042683:Angiopoietin-1; D042702:Angiopoietin-2; D016207:Cytokines; D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; C059485:matrigel; D012313:RNA; D003094:Collagen