[Single-cell transcriptome analysis reveals heterogeneous features of cancer-associated fibroblasts in acral...

Objective To investigate the heterogeneity characteristics of cancer-associated fibroblasts (CAF) in acral melanoma (AM) and their functional roles in the tumor microenvironment (TME), providing a theoretical basis for developing effective therapeutic strategies. Methods The single-cell RNA sequencing data used in this study were previously generated by our research group and have been deposited in the HRA001804 dataset of the National Genomics Data Center (NGDC). Five AM patient samples were selected from this dataset for analysis, including 4 primary tumor samples (PL1, PL2, PL4, PL5) and 1 lymph node metastasis sample (LG2). Bioinformatics methods including unsupervised clustering, pseudotime trajectory analysis, transcription factor regulatory network analysis, and cell-cell communication analysis were used for data mining. Results Three subtypes of CAF were identified from 41 960 high-quality cells: immunomodulatory CAF (iCAF), myofibroblastic CAF (mCAF), and proliferative CAF (pCAF). Pseudotime trajectory analysis demonstrated that mCAF were located at the initiation of differentiation, while iCAF and pCAF were distributed in distinct terminal branches. FOS-like 1, AP-1 transcription factor subunit (FOSL1) was identified as a key transcription factor regulating the differentiation of CAF into pCAF, and its co-expression modules were enriched in the P53 signal pathway, AP-1 transcription factor network, and MYC-mediated cell proliferation pathways. Cell communication analysis revealed an interaction network centered on iCAF, with critical pathways including CSPG4-(ITGA2+ITGB1), GDF15-TGFBR2, LGALS9-CD45/CD44, and CD70-CD27 signal pathways. Conclusion CAF in AM exhibits high heterogeneity, with FOSL1 playing a key regulatory role in CAF differentiation. CAF participates in tumor microenvironment regulation through complex intercellular communication networks. These findings provide important insights into understanding the biological characteristics of acral melanoma and developing targeted therapeutic strategies.