title: Knockout of HIF-1α in tumor-associated macrophages enhances M2 polarization and attenuates their pro-angiogenic responses.
abstract: Tumor-associated macrophages (TAMs) constitute major infiltrates of solid tumors and express a marker profile that characterizes alternatively activated macrophages (MФs). TAMs accumulate in hypoxic tumor regions, express high amounts of hypoxia-inducible factor-1 (HIF-1) and contribute to tumor angiogenesis and invasiveness. However, the precise role of HIF-1 on MФ infiltration and phenotype alterations remains poorly defined. Therefore, we cocultured wild type (wt) versus HIF-1α(-/-) MФs with tumor spheroids. Both, wt and HIF-1α(-/-) MФs, infiltrated hypoxic regions of tumor spheroids at equal rates and got alternatively activated. Interestingly, significantly higher amounts of HIF-1α(-/-) MФs expressed the TAM markers CD206 and stabilin-1 compared with wt phagocytes. Stimulation of infiltrated TAMs with lipopolysaccharide (LPS)/interferon-γ revealed a reduced expression of the pro-inflammatory markers interleukin (IL)-6, tumor necrosis factor-α and inducible nitric oxide synthase in HIF-1α(-/-) MФs. Furthermore, HIF-1α(-/-) MФs were less cytotoxic toward tumor cells. Although infiltration of MФs increased the invasive potential of tumor spheroids independently of HIF-1, the ability to stimulate differentiation of stem cells toward CD31-positive cells was triggered by wt but not by HIF-1α(-/-) MФs. Our data suggest that HIF-1α-deficient MФs develop a more prominent TAM marker profile accompanied by reduced cytotoxicity, whereas HIF-1 seems indispensable for the angiogenesis-promoting properties of TAMs.
authors.affiliation: Institute of Biochemistry I--Pathobiochemistry/Zentrum für Arzneimittelforschung, Entwicklung und Sicherheit, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Werno
authors.forename: Heidi
authors.initials: H
authors.lastname: Menrad
authors.forename: Andreas
authors.initials: A
authors.lastname: Weigert
authors.forename: Nathalie
authors.initials: N
authors.lastname: Dehne
authors.forename: Sergij
authors.initials: S
authors.lastname: Goerdt
authors.forename: Kai
authors.initials: K
authors.lastname: Schledzewski
authors.forename: Julia
authors.initials: J
authors.lastname: Kzhyshkowska
authors.forename: Bernhard
authors.initials: B
authors.lastname: Brüne
mesh_terms: D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000032:analysis; D045744:Cell Line, Tumor; D016764:Cell Polarity; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D007371:Interferon-gamma / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis; D037181:Lectins, C-Type / Q000032:analysis; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000502:physiology*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000032:analysis; D051379:Mice; D009361:Neoplasm Invasiveness; D009369:Neoplasms / Q000098:blood supply* / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000209:etiology*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D011956:Receptors, Cell Surface / Q000032:analysis; D016201:Receptors, Lymphocyte Homing / Q000032:analysis; D018874:Spheroids, Cellular / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; C497442:HIF1A protein, human; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015850:Interleukin-6; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011956:Receptors, Cell Surface; D016201:Receptors, Lymphocyte Homing; C449926:STAB1 protein, human; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II