Single-cell RNA sequencing analysis reveals the heterogeneity and effect of TAMs in colorectal cancer.

Colorectal cancer (CRC) is a prevalent and malignant tumor of the digestive system, characterized by high incidence and mortality rates. This study aimed to investigate the heterogeneity of the tumor microenvironment (TME) and the involvement of immune cells in CRC. Single-cell RNA sequencing (scRNA-seq) data obtained from the Gene Expression Omnibus database were used to analyze and identify six major cell types across normal, core, and border tumor samples. A total of 27 414 cells from various regions of patients with CRC were selected for subsequent analyses. Cellular interaction analysis revealed that differential signaling pathways between the TME and normal tissues, with several pathways involving interactions between myeloid cells and epithelial cells. Myeloid cells were extracted and classified into six subtypes based on markers identified in the literature. Monocle3 revealed the trajectory of tumor-associated macrophages (TAMs) and identified genes associated with pseudotime. Single-Cell ENrichment analysis for Interpreting Cellular Heterogeneity analysis identified specific regulons and target genes associated with TAMs. This study reanalyzed single-cell RNA-sequencing data and provided insights into the heterogeneity of the TME, particularly in relation to the role of TAMs.