title: Paracrine regulation of vascular endothelial growth factor--a expression during macrophage-melanoma cell interaction: role of monocyte chemotactic protein-1 and macrophage colony-stimulating factor.
abstract: Tumor-associated macrophages are major infiltrates of human solid malignancies and play an important role in tumor angiogenesis by production of angiogenic factors. In the present study, we examined whether macrophage- melanoma cell interaction regulates vascular endothelial cell growth factor-A (VEGF-A) expression in macrophages. We analyzed the expression of mediators of monocyte recruitment and differentiation, such as monocyte chemotactic protein-1 (MCP-1) and macrophage colony-stimulating factor (M-CSF) in malignant melanoma specimens and tumor cells with different metastatic potential. Our data demonstrate that MCP-1 and M-CSF are differentially expressed in human malignant melanomas from different thickness and depth of invasion and cell lines. Next, we examined the effect of MCP-1 and M-CSF on modulation of VEGFA expression in monocytes/macrophages. Treatment of human monocytes with M-CSF and MCP-1 enhanced VEGF-A expression by increased hypoxia-inducible factor-1alpha (HIF-1alpha) expression and enhanced activation of the hypoxia response element (HRE). Further activation of monocytes and monocyte-derived macrophages (MDM) by lipopolysaccharide (LPS) caused an increase in VEGF-A expression. We demonstrate that coculture of melanoma cells with monocytes enhanced VEGF-A secretion, and conditioned medium from MDMs enhanced melanoma cell expression of VEGF-A. Furthermore, conditioned medium from melanoma cells enhanced VEGF-A expression in human monocytes, which was abrogated by anti-M-CSF neutralizing antibody. In summary, we demonstrate that MCP-1 and M-CSF, critical for monocyte recruitment, activation, and differentiation, differentially regulate VEGF-A expression and may play an important role in monocyte/macrophage- mediated tumor angiogenesis.
authors.affiliation: Department of Pathology and Microbiology, The University of Nebraska Medical Center, 985845 Nebraska Medical Center, Omaha, NE 68198-5845, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Varney
authors.forename: Kimberlee J
authors.initials: KJ
authors.lastname: Olsen
authors.forename: R Lee
authors.initials: RL
authors.lastname: Mosley
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Singh
mesh_terms: D015153:Blotting, Western; D002448:Cell Adhesion; D002450:Cell Communication; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D018932:Chemokine CCL2 / Q000378:metabolism*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008070:Lipopolysaccharides / Q000737:chemistry; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D009389:Neovascularization, Pathologic; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D018932:Chemokine CCL2; D017077:Culture Media, Conditioned; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D016173:Macrophage Colony-Stimulating Factor