title: Metastatic breast cancer induces an osteoblast inflammatory response.
abstract: Breast cancer preferentially metastasizes to the skeleton, a hospitable environment that attracts and allows breast cancer cells to thrive. Growth factors released as bone is degraded support tumor cell growth, and establish a cycle favoring continued bone degradation. While the osteoclasts are the direct effectors of bone degradation, we found that osteoblasts also contribute to bone loss. Osteoblasts are more than intermediaries between tumor cells and osteoclasts. We have presented evidence that osteoblasts contribute through loss of function induced by metastatic breast cancer cells. Metastatic breast cancer cells suppress osteoblast differentiation, alter morphology, and increase apoptosis. In this study we show that osteoblasts undergo an inflammatory stress response in the presence of human metastatic breast cancer cells. When conditioned medium from cancer cells was added to human osteoblasts, the osteoblasts were induced to express increased levels of IL-6, IL-8, and MCP-1; cytokines known to attract, differentiate, and activate osteoclasts. Similar findings were seen with murine osteoblasts and primary murine calvarial osteoblasts. Osteoblasts are co-opted into creating a microenvironment that exacerbates bone loss and are prevented from producing matrix proteins for mineralization. This is the first study implicating osteoblast produced IL-6, IL-8 (human; MIP-2 and KC mouse), and MCP-1 as key mediators in the osteoblast response to metastatic breast cancer cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Kinder
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Chislock
authors.forename: Karen M
authors.initials: KM
authors.lastname: Bussard
authors.forename: Laurie
authors.initials: L
authors.lastname: Shuman
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Mastro
mesh_terms: D000818:Animals; D001859:Bone Neoplasms / Q000276:immunology / Q000556:secondary*; D001862:Bone Resorption / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D001943:Breast Neoplasms / Q000276:immunology / Q000473:pathology*; D002113:Calcification, Physiologic / Q000502:physiology; D002277:Carcinoma / Q000276:immunology / Q000556:secondary*; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D018932:Chemokine CCL2 / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D051379:Mice; D009362:Neoplasm Metastasis / Q000276:immunology / Q000503:physiopathology*; D010000:Osteitis / Q000209:etiology / Q000503:physiopathology*; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D010010:Osteoclasts / Q000378:metabolism; D010012:Osteogenesis / Q000502:physiology; D013312:Stress, Physiological / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D017077:Culture Media, Conditioned; D016207:Cytokines; D015850:Interleukin-6; D016209:Interleukin-8