Pro-tumorigenic functions of macrophages at the primary, invasive and metastatic tumor site

Area of Science:

• Oncology
• Immunology
• Cell Biology

Background:

• The tumor microenvironment (TME) is dynamic and influences cancer progression from initiation to metastasis.
• Tumor-associated macrophages (TAMs) are key cellular components of the TME, exhibiting diverse and context-dependent phenotypes.
• Traditional M1/M2 classification oversimplifies TAM functions, which are critical in shaping the TME.

Purpose of the Study:

• To elucidate the multifaceted roles of TAMs in cancer progression and metastasis.
• To highlight the phenotypic plasticity of TAMs in response to microenvironmental cues.
• To underscore the therapeutic potential of targeting TAMs.

Main Methods:

• Review of existing literature on TAM biology and function in cancer.
• Analysis of TAM involvement across different stages of tumor evolution, including primary tumor formation, invasion, and pre-metastatic niche formation.
• Discussion of TAM polarization and functional divergence within the TME.

Main Results:

• TAMs contribute to early oncogenic mutations (M1-like) and promote tumor growth, angiogenesis, and immunosuppression (M2-like).
• TAMs facilitate cancer cell invasion, intravasation, and the establishment of pre-metastatic niches.
• TAMs are involved in shaping the primary, micro-invasive, and pre-metastatic TMEs.

Conclusions:

• TAMs exhibit remarkable phenotypic plasticity, influenced by the TME, enabling them to support various stages of cancer progression.
• The diverse functions of TAMs make them significant therapeutic targets for cancer treatment.
• Targeting TAMs could offer novel strategies to inhibit tumor evolution and metastasis.