Abstract:
The occurrence and development of colorectal cancer (CRC) are not only related to the characteristics of the tumor cells but also to the tumor microenvironment (TME). Tumor cells and the TME secrete a variety of cytokines to recruit monocytes in the circulating blood to the TME and polarize them into tumor-associated macrophages (TAMs). As one of the most abundant immune cells in the TME, TAMs have functions and characteristics similar to those of M2 macrophages. They mainly stimulate tumor cell proliferation, angiogenesis, and matrix remodeling and promote tumor cell invasion and metastasis. Studies have shown that in most tumors, TAMs mainly have a tumor-promoting effect and are related to the poor prognosis of patients; however, in CRC, the role of TAMs remains controversial. This article reviews the role and mechanisms of TAMs in the TME of CRC to examine the influence of TAMs on the progression and prognosis of CRC and to explore the feasibility of TAMs as targets for CRC immunotherapy.