title: Fibroblast growth factor receptor 1 activation in mammary tumor cells promotes macrophage recruitment in a CX3CL1-dependent manner.
abstract: Tumor formation is an extensive process requiring complex interactions that involve both tumor cell-intrinsic pathways and soluble mediators within the microenvironment. Tumor cells exploit the intrinsic functions of many soluble molecules, including chemokines and their receptors, to regulate pro-tumorigenic phenotypes that are required for growth and progression of the primary tumor. Previous studies have shown that activation of inducible FGFR1 (iFGFR1) in mammary epithelial cells resulted in increased proliferation, migration, and invasion in vitro and tumor formation in vivo. These studies also demonstrated that iFGFR1 activation stimulated recruitment of macrophages to the epithelium where macrophages contributed to iFGFR1-mediated epithelial cell proliferation and angiogenesis. The studies presented here further utilize this model to identify the mechanisms that regulate FGFR1-induced macrophage recruitment. Results from this study elucidate a novel role for the inflammatory chemokine CX3CL1 in FGFR1-induced macrophage migration. Specifically, we illustrate that activation of both the inducible FGFR1 construct in mouse mammary epithelial cells and endogenous FGFR in the triple negative breast cancer cell line, HS578T, leads to expression of the chemokine CX3CL1. Furthermore, we demonstrate that FGFR-induced CX3CL1 is sufficient to recruit CX3CR1-expressing macrophages in vitro. Finally, blocking CX3CR1 in vivo leads to decreased iFGFR1-induced macrophage recruitment, which correlates with decreased angiogenesis. While CX3CL1 is a known target of FGF signaling in the wound healing environment, these studies demonstrate that FGFR activation also leads to induction of CX3CL1 in a tumor setting. Furthermore, these results define a novel role for CX3CL1 in promoting macrophage recruitment during mammary tumor formation, suggesting that the CX3CL1/CX3CR1 axis may represent a potential therapeutic approach for targeting breast cancers associated with high levels of tumor-associated macrophages.
authors.affiliation: Microbiology, Immunology, and Cancer Biology Graduate Program, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Johanna R
authors.initials: JR
authors.lastname: Reed
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Stone
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Beadnell
authors.forename: Yungil
authors.initials: Y
authors.lastname: Ryu
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Griffin
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Schwertfeger
mesh_terms: D000818:Animals; D001943:Breast Neoplasms; D000073883:CX3C Chemokine Receptor 1; D045744:Cell Line, Tumor; D002465:Cell Movement; D002471:Cell Transformation, Neoplastic; D054428:Chemokine CX3CL1 / Q000378:metabolism / Q000502:physiology*; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D005260:Female; D006801:Humans; D008264:Macrophages / Q000378:metabolism / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000098:blood supply / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism*; D019707:Receptors, Chemokine / Q000378:metabolism
chemical_list: D000073883:CX3C Chemokine Receptor 1; C515538:CX3CL1 protein, human; C095235:CX3CR1 protein, human; D054428:Chemokine CX3CL1; D019707:Receptors, Chemokine; D051496:Receptor, Fibroblast Growth Factor, Type 1