Single-Cell and Spatial Transcriptomics Delineate the Microstructure and Immune Landscape of Intrahepatic Cholangiocarcinoma in the Leading-Edge Area.

Intrahepatic cholangiocarcinoma (ICC) tumor cells and their interactions with the immune microenvironment, particularly at the leading-edge area, have been underexplored. This study employs single-cell RNA sequencing (scRNA-seq) and spatial transcriptome (ST) analysis on samples from the tumor core, adjacent non-tumorous tissue, and the leading-edge area of nine ICC patients. These findings indicate that tumor cells at the leading-edge area demonstrate enhanced proliferation and are tightly associated with the stroma, including endothelial cells and POSTN+ FAP+ fibroblasts. Notably, CD8+ T cells in this region exhibit a naive phenotype with low cytotoxicity and signs of exhaustion, likely due to compromised antigen presentation by antigen-presenting cells (APCs). The predominant CD8+ T cell subset, mucosal-associated invariant T (MAIT) cells, recruits SPP1+ macrophages within the stroma. This interaction, along with the presence of POSTN+ cancer-associated fibroblasts (CAFs) and endothelial cells, forms a unique "triad structure" that fosters tumor growth and ICC progression. The research highlights the intricate characteristics and interactions of ICC tumor cells in the leading-edge area, offering insights into potential therapeutic targets for intervention.