Identification of a unique subpopulation of mucosal fibroblasts in colorectal cancer with tumor-restraining characteristics

While tumor-restraining cancer-associated fibroblasts (Tr-CAFs) have been investigated in various cancers, their existence in colorectal cancer remains unexplored. We performed a comprehensive analysis of diverse colorectal cancer datasets, including single-cell RNA-seq/ATAC-seq data from colorectal samples, TCGA RNA-seq, and histological samples. We identified a fibroblast subpopulation uniquely expressing ADAMDEC1, CXCL14, EDNRB, and PROCR, strongly associated with favorable patient outcomes, implicating their role as Tr-CAFs. Pseudotime trajectory analysis suggested these cells as terminally differentiated mucosal fibroblasts. Pathway analysis indicated that this subpopulation was significantly associated with tumor-suppressive functions, such as reduced extracellular matrix secretion, augmented immune response, and enhanced responsiveness to immunotherapy. Single-cell ATAC-seq analysis revealed that this putative Tr-CAF subset exhibited unique epigenetic profiles characterized by superenhancer-regulated tumor-suppressive genes, thereby supporting its identity as a stable lineage rather than a transient phenotypic state induced by external stimuli. Immunohistochemistry showed that key markers identifying this putative Tr-CAF subset—CXCL14, ADAMDEC1, EDNRB, and PROCR—were predominantly localized to fibroblasts within normal colonic mucosa and less frequently in cancer-associated fibroblasts (CAFs). Their expression levels exhibited statistically significant associations with favorable clinicopathological indicators, including prolonged disease-free survival. Notably, ADAMDEC1 expression in CAFs was significantly correlated with T-cell infiltration within the tumor microenvironment. In conclusion, our investigation elucidates the characteristics and clinical relevance of Tr-CAFs in colorectal cancer, suggesting novel avenues for targeted anti-CAF therapy.