Tumor-associated macrophages in breast cancer as potential biomarkers for new treatments and diagnostics

Abstract

While several inflammatory cell types participate in cancer development, macrophages specifically play a key role in breast cancer, where they appear to be part of the pathogenesis of high-grade tumors. Tumor-associated macrophages (TAMs) produce factors that promote angiogenesis, remodel tissue and dampen the immune response to tumors. Specific macrophage types contribute to increased metastases in animal models, while human studies show an association between TAMs and tumors with poor prognostic features. Macrophages display a spectrum of phenotypic states, with the tumor microenvironment skewing TAMs towards a ‘nonclassical’ activation state, known as the M2, or wound healing/regulatory state. These TAMs are found in high-risk breast cancers, making them an important therapeutic target to explore. Improved techniques for identifying TAMs should translate into clinical applications for prognosis and treatment.

Keywords::

• alternative activation
• breast cancer
• leukocyte infiltrate
• tumor-associated macrophage

Financial & competing interests disclosure

Rita Mukhtar received support from the California Breast Cancer Research Program (post-doctoral fellowship 15FB-0108). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Notes

^†Seen in human tissue.

^‡Seen in murine models.