title: Tumor exosomes inhibit differentiation of bone marrow dendritic cells.
abstract: The production of exosomes by tumor cells has been implicated in tumor-associated immune suppression. In this study, we show that, in mice, exosomes produced by TS/A murine mammary tumor cells target CD11b(+) myeloid precursors in the bone marrow (BM) in vivo, and that this is associated with an accumulation of myeloid precursors in the spleen. Moreover, we demonstrate that TS/A exosomes block the differentiation of murine myeloid precursor cells into dendritic cells (DC) in vitro. Addition of tumor exosomes at day 0 led to a significant block of differentiation into DC, whereas addition at later time points was less effective. Similarly, exosomes produced by human breast tumor cells inhibited the differentiation of human monocytes in vitro. The levels of IL-6 and phosphorylated Stat3 were elevated 12 h after the tumor exosome stimulation of murine myeloid precursors, and tumor exosomes were less effective in inhibiting differentiation of BM cells isolated from IL-6 knockout mice. Addition of a rIL-6 to the IL-6 knockout BM cell culture restored the tumor exosome-mediated inhibition of DC differentiation. These data suggest that tumor exosome-mediated induction of IL-6 plays a role in blocking BM DC differentiation.
authors.affiliation: Department of Medicine, Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Yu
authors.forename: Cunren
authors.initials: C
authors.lastname: Liu
authors.forename: Kaihong
authors.initials: K
authors.lastname: Su
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
authors.forename: Yuelong
authors.initials: Y
authors.lastname: Liu
authors.forename: Liming
authors.initials: L
authors.lastname: Zhang
authors.forename: Chuanyu
authors.initials: C
authors.lastname: Li
authors.forename: Yingzi
authors.initials: Y
authors.lastname: Cong
authors.forename: Robert
authors.initials: R
authors.lastname: Kimberly
authors.forename: William E
authors.initials: WE
authors.lastname: Grizzle
authors.forename: Carla
authors.initials: C
authors.lastname: Falkson
authors.forename: Huang-Ge
authors.initials: HG
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology; D005089:Exocytosis / Q000276:immunology*; D005260:Female; D006131:Growth Inhibitors / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008546:Melanoma, Experimental / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D023461:Myeloid Progenitor Cells / Q000166:cytology / Q000276:immunology; D022142:Secretory Vesicles / Q000276:immunology* / Q000378:metabolism / Q000473:pathology
chemical_list: D006131:Growth Inhibitors