Macrophage conditioned media promotes adipocyte cancer-association, which in turn stimulates breast cancer proliferation and migration

Background: Breast cancer is the most common cancer in women and the leading cause of female cancer deaths worldwide. Obesity causes chronic inflammation and is a risk factor for post-menopausal breast cancer and poor prognosis. Obesity triggers increased infiltration of macrophages into adipose tissue, yet little research has focused on the effects of macrophages in early stages of breast tumor development in obese patients. In this study, the effects of pro-inflammatory macrophages on breast cancer-adipocyte crosstalk were investigated. Methods: An innovative human cell co-culture system was used to model the paracrine interactions among adipocytes, macrophages, and breast cancer cells, and how they facilitate tumor progression. The effects on cancer cells were examined using cell counts and migration assays. Quantitative reverse-transcription polymerase chain reaction was used to measure the expression levels of several cytokines and proteases to analyze adipocyte cancer-association. Results: Macrophage conditioned media intensified the effects of breast cancer-adipocyte crosstalk. Adipocytes became delipidated and increased production of pro-inflammatory cytokines, even in the absence of cancer cells, although the expression levels were highest with all three cell components. As a result, co-cultured breast cancer cells became more aggressive, with increased proliferation and migration compared to adipocyte-breast cancer co-cultures treated with unconditioned media. Conclusions: Macrophage conditioned media promotes adipocyte cancer-association. These macrophage-adipocyte paracrine interactions promote breast cancer cell proliferation and migration. Thus, macrophages may contribute to adipocyte inflammation and cancer-association and promote breast cancer progression.