Macrophages in melanoma: A double-edged sword and targeted therapy strategies (Review)

Melanoma, which evolves from melanocytes, is the most malignant skin cancer and is highly fatal, although it only accounts for 4% of all skin cancers. Numerous studies have demonstrated that melanoma has a large tumor mutational burden, which means that melanoma has great potential to achieve immune evasion. Tumor-associated macrophages (TAMs) are an important component of both the immune system and tumor microenvironment. Several studies have demonstrated their double-edged sword effects on melanoma. The present review focuses on the role of TAMs in melanoma development, including regulation of proliferation, invasion, metastasis, angiogenesis and chemical resistance of melanoma. Furthermore, the existing mechanisms of action of the TAM-targeting treatments for melanoma are reviewed. More broadly, the weak points of existing research and the direction of future research are finally identified and described.