Crosstalk Between Macrophages and Breast Cancer Cells: Networking Within Tumors

Tumor associated macrophages (TAMs) are one of the most prominent immune cells in the breast tumor microenvironment (TME). TAMs are categorised into classically activated anti-tumorigenic M1 and alternatively activated pro-tumorigenic M2 macrophages. TAMs are known to promote cancer pathogenesis by facilitating cancer cell and cancer stem cell growth, angiogenesis, immune evasion, invasion, and migration. Consequently, TAMs drive cancer progression towards metastasis. This chapter describes the role of TME in driving monocyte recruitment and polarization toward the M2 phenotype. We also illustrate the modalities of intercellular networking such as paracrine signaling, exosomes, and tunneling nanotubes (TNTs) that TAMs and cancer cells employ within TME to communicate with each other and with other cells of TME to facilitate the dynamic process of cancer progression. Finally, we discuss the clinical implications of TAMs in breast cancer and potential therapeutic strategies targeting TAM recruitment, polarization, and TAM-mediated immune evasion for effective cancer therapy.