AUTHOR=Fujimura Taku , Kambayashi Yumi , Fujisawa Yasuhiro , Hidaka Takanori , Aiba Setsuya 

TITLE=Tumor-Associated Macrophages: Therapeutic Targets for Skin Cancer

JOURNAL=Frontiers in Oncology

VOLUME=Volume 8 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2018.00003

DOI=10.3389/fonc.2018.00003

ISSN=2234-943X

ABSTRACT=Tumor-associated macrophages (TAMs) and regulatory T cells (Tregs) are significant components of the microenvironment of solid tumors in the majority of cancers. TAMs sequentially develop from monocytes into functional macrophages. In each differentiation stage, TAMs obtain various immunosuppressive functions to maintain the tumor microenvironment (e.g., expression of immune checkpoint molecules, production of Treg-related chemokines and cytokines, production of arginase I). Although the main population of TAMs is immunosuppressive M2 macrophages, TAMs can be modulated into M1-type macrophages in each differential stage, leading to the suppression of tumor growth. Because the administration of certain drugs or stromal factors can stimulate TAMs to produce specific chemokines, leading to the recruitment of various tumor-infiltrating lymphocytes, TAMs can serve as targets for cancer immunotherapy. In this review, we discuss the differentiation, activation, and immunosuppressive function of TAMs, as well as their benefits in cancer immunotherapy.
Context
1. Introduction
2. Differentiation and activation of TAMs in tumors
3. Roles of TAMs in maintaining the immunosuppressive microenvironment
	3.1 Chemokines from TAMs determine the immunological microenvironment in tumors
	3.2 Direct suppressive function of TAMs
3.3 Angiogenetic factors from TAMs
4. Clinical benefits of TAMs
4.1 The effects of anti-cancer drug for TAMs
4.2 TAMs as a biomarker for disease activity and adverse events
5. Concluding remarks