Upper left panel: Image representing a protein array of 507 proteins used for detection of soluble factors present in a mixture of CMCAAT from two patients. Each protein is spotted in duplicate. The boxes show the positive controls. The brackets indicate adiponectin (1) confirming the adipose nature of CMCAAT, GCSF (2), IL-6 (3), IL-8 (4), leptin (5), LIF (6), OSM (7). Upper right panels: western blot analysis of Y705 pSTAT3 of MCF-7 cells treated for 48h with control medium; neutralizing antibodies against hIL-6, hLIF and hIL-8 (1 µg/ml); rhIL-6, rhLIF and rhIL-8 (10 ng/ml); combination of the recombinant protein with the neutralizing antibody (same concentrations); western blot analysis of MCF-7 cells treated for 48h with CMCAAT and neutralizing antibodies against hIL-6, hLIF and hIL-8 at indicated concentrations. Lower panel: Phase-contrast images of MCF-7 cells treated or 48h with control medium, rhIL-6, rhLIF and rhIL-8 at indicated concentrations, CMCAAT and CMCAAT combined with neutralizing antibodies against hIL-6, hLIF and hIL-8 at indicated concentrations (Scale bar is 100 µm).
ARTICLE ABSTRACTIncreasing evidence supports the critical roles played by adipose tissue in breast cancer progression. Yet, the mediators and mechanisms are poorly understood. Here, we show that breast cancer–associated adipose tissue from freshly isolated tumors promotes F-actin remodeling, cellular scattering, invasiveness, and spheroid reorganization of cultured breast cancer cells. A combination of techniques, including transcriptomics, proteomics, and kinomics enabled us to identify paracrine secretion of oncostatin M (OSM) by cancer-associated adipose tissue. Specifically, OSM, expressed by CD45+ leucocytes in the stromal vascular fraction, induced phosphorylation of STAT3 (pSTAT3-) Y705 and S727 in breast cancer cells and transcription of several STAT3-dependent genes, including S100 family members S100A7, S100A8, and S100A9. Autocrine activation of STAT3 in MCF-7 cells ectopically expressing OSM-induced cellular scattering and peritumoral neovascularization of orthotopic xenografts. Conversely, selective inhibition of OSM by neutralizing antibody and Jak family kinases by tofacitinib inhibited STAT3 signaling, peritumoral angiogenesis, and cellular scattering. Importantly, nuclear staining of pSTAT3-Y705 identified at the tumor invasion front in ductal breast carcinomas correlates with increased lymphovascular invasion. Our work reveals the potential of novel therapeutic strategies targeting the OSM and STAT3 axis in patients with breast cancer harboring nuclear pSTAT3-Y705. Cancer Res; 74(23); 6806–19. ©2014 AACR.