Obesity-Activated Lung Stromal Cells Promote Myeloid Lineage Cell Accumulation and Breast Cancer Metastasis

Obesity is correlated with increased incidence of breast cancer metastasis; however, the mechanisms underlying how obesity promotes metastasis are unclear. In a diet-induced obese mouse model, enhanced lung in both presence and absence primary mammary tumors recruitment myeloid lineage cells into lungs. tumors, mice demonstrated numbers elevated collagen fibers within stroma, reminiscent premetastatic niches formed by tumors. Lung stromal isolated from tumor-naïve showed proliferation, contractility, expression extracellular matrix, inflammatory markers transforming growth factor beta-1 (TGFβ1). Conditioned media promoted cell migration vitro response to colony-stimulating 2 (CSF2) invasion tumor cells. Together, these results suggest that prior formation, alters microenvironment, creating conducive metastatic growth.