title: Differential roles of vascular endothelial growth factor receptors 1 and 2 in dendritic cell differentiation.
abstract: Impaired Ag-presenting function in dendritic cells (DCs) due to abnormal differentiation is an important mechanism of tumor escape from immune control. A major role for vascular endothelial growth factor (VEGF) and its receptors, VEGFR1/Flt-1 and VEGFR2/KDR/Flk-1, has been documented in hemopoietic development. To study the roles of each of these receptors in DC differentiation, we used an in vitro system of myeloid DC differentiation from murine embryonic stem cells. Exposure of wild-type, VEGFR1(-/-), or VEGFR2(-/-) embryonic stem cells to exogenous VEGF or the VEGFR1-specific ligand, placental growth factor, revealed distinct roles of VEGF receptors. VEGFR1 is the primary mediator of the VEGF inhibition of DC maturation, whereas VEGFR2 tyrosine kinase signaling is essential for early hemopoietic differentiation, but only marginally affects final DC maturation. SU5416, a VEGF receptor tyrosine kinase inhibitor, only partially rescued the mature DC phenotype in the presence of VEGF, suggesting the involvement of both tyrosine kinase-dependent and independent inhibitory mechanisms. VEGFR1 signaling was sufficient for blocking NF-kappaB activation in bone marrow hemopoietic progenitor cells. VEGF and placental growth factor affect the early stages of myeloid/DC differentiation. The data suggest that therapeutic strategies attempting to reverse the immunosuppressive effects of VEGF in cancer patients might be more effective if they specifically targeted VEGFR1.
authors.affiliation: Vanderbilt University, 2200 Pierce Avenue, 648 PB, Nashville, TN 37232, USA. Mikhail.Dikov@vanderbilt.edu
authors.forename: Mikhail M
authors.initials: MM
authors.lastname: Dikov
authors.forename: Joyce E
authors.initials: JE
authors.lastname: Ohm
authors.forename: Neelanjan
authors.initials: N
authors.lastname: Ray
authors.forename: Elena E
authors.initials: EE
authors.lastname: Tchekneva
authors.forename: Jared
authors.initials: J
authors.lastname: Burlison
authors.forename: Drew
authors.initials: D
authors.lastname: Moghanaki
authors.forename: Sorena
authors.initials: S
authors.lastname: Nadaf
authors.forename: David P
authors.initials: DP
authors.lastname: Carbone
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000276:immunology / Q000378:metabolism; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000276:immunology / Q000378:metabolism*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000276:immunology / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000276:immunology / Q000378:metabolism*
chemical_list: D018952:Antigens, CD34; D004791:Enzyme Inhibitors; D007211:Indoles; D016328:NF-kappa B; D011758:Pyrroles; D042461:Vascular Endothelial Growth Factor A; C116890:Semaxinib; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2