Single-cell RNA sequencing reveals the heterogeneity of tumor-associated macrophage in three subtypes of breast cancer

The heterogeneity and the complex cellular interaction of tumor-associated macrophages (TAMs) have a crucial effect on different subtypes of breast cancer (BC) progression and response to treatment. In this work, we combine published single-cell RNA sequencing data from 24 BC patients and co-culture experiments of macrophages with three subtypes of BC to identify heterogeneity of TAMs. We find that TAMs in the three subtypes of BC not only have diverse features and functions, but also emerge to the crosstalk within subtypes. The results of pathway enrichment analysis, cellular communication, and ligand-receptor pair analysis show that heterogeneous TAMs can activate different pathways in cancer cells and epithelial cells by expressing specific ligands and binding to different receptors. We revealed the unique role of heterogeneous TAMs in regulating the biological functions of different tumor microenvironments, and by targeting heterogeneous macrophages in different subtypes of breast cancer may provide a novel insight for the precision immunotherapy of breast cancer.