Soluble Factors Involved in Cancer Cell–Macrophage Interaction Promote Breast Cancer Growth

Abstract

Background/Aim: Recent studies have indicated the clinical significance of tumor-associated macrophages (TAMs) in breast cancer; however, the detailed mechanisms of cell–cell interactions between TAMs and cancer cells remain unclear. Materials and Methods: In vitro cell culture studies using human monocyte-derived macrophages and breast cancer cell lines were performed to test which cytokines would be involved in cell-cell interactions between cancer cells and macrophages. In addition, studies using human resected samples and animal breast cancer models were performed to examine the significance of TAMs in cancer development. Results: Osteopontin, HB-EGF, and IL-6 were suggested to be macrophage-derived growth factors for breast cancer cells. FROUNT inhibitor significantly blocked TAM infiltration and subcutaneous tumor growth in an E0771 mouse breast cancer model. Conclusion: TAMs express growth factors, such as osteopontin, for cancer cells, and targeting of TAM infiltration might be a promising approach for anti-breast cancer therapy.