Functional Subtypes of Macrophages in the Tumor Microenvironment from a Single-Cell Perspective

The initiation and progression of tumors were closely associated with the tumor microenvironment. TAM (tumor-associated macrophage), serving as key immune cells within this milieu, exhibited significant heterogeneity. This rendered the conventional M1/M2 binary classification inadequate for accurately delineating their functional profiles. Leveraging single-cell RNA sequencing technology, this review refined the classification of TAMs into six distinct subtypes based on functional modules across multiple tumor types, including hepatocellular carcinoma, colorectal cancer, and pancreatic cancer. The subtypes were categorized as follows: pro-angiogenic/tumormetastatic, immunosuppressive, immunostimulatory, proliferative, metabolic, and a minor group of other specialized subtypes. Furthermore, the review provided the marker genes and signature gene sets specific to each TAM subtype and evaluated the translational potential of several key indicators in clinical settings. Considering the limitations and shortcomings inherent in current research, new perspectives were proposed on how single-cell RNA sequencing technology could contribute to advancing precision medicine in oncology.

CSTR: 32200.14.cjcb.2026.02.0021