Cancer-associated fibroblasts and immune escape-related genes serve as biological markers for the prognosis of colorectal cancer

Colorectal cancer (CRC) is a common malignant tumor with a steadily rising incidence rate, and it is often diagnosed at an advanced stage. Immunotherapy has emerged as a promising alternative to surgical resection. Cancer-associated fibroblasts (CAFs) play a critical role in the tumor microenvironment (TME) and are closely associated with tumor immune evasion. This study aims to identify genes associated with CAFs and immune evasion in CRC, and to explore their underlying mechanisms and potential clinical applications in CRC. Based on CRC transcriptomic data from TCGA and GEO (GSE39582), this study identified differentially expressed genes associated with tumor-associated fibroblasts and immune evasion (CAFIERDEGs) and performed GO/KEGG functional enrichment analysis on them. A prognostic risk model was constructed based on CAFIERDEGs, followed by survival analysis and validation. Additionally, key genes were identified through the construction of a protein-protein interaction (PPI) network, and differences in immune checkpoint expression, immune cell infiltration, and immunotherapy response were systematically evaluated across different risk groups. Finally, the key genes were experimentally validated using single-cell RNA sequencing, immunohistochemistry, and qPCR. Five hub genes (SOX2, CXCL11, SPP1, APOE, and CXCL8) were screened. These genes are involved in the regulation of the immune response, cytokine activity, and the Toll-like receptor signaling pathway. CRC patients were classified into two distinct molecular subtypes based on the expression profiles of these genes. The prognostic risk model revealed significant differences in overall survival rates. The tumor immune dysfunction and rejection (TIDE) score was significantly lower in the low-risk group. The tumor mutational burden (TMB) was higher, and the expression of most immune checkpoint genes increased. This indicates a stronger potential reactivity to immunotherapy. Experiments confirmed that the expressions of CXCL8, CXCL11, and SPP1 were significantly upregulated in CAFs, while APOE and SOX2 expressions were significantly downregulated. This study identified five CAFIERGs and constructed a prognostic model for CRC by integrating CAFs and immune escape-related genes. This model can predict the immunotherapy response and prognosis of CRC patients. These findings offer potential therapeutic targets for improving prognostic evaluation and guiding immunotherapy strategies in CRC patients.