Fig. 4

Characterization of the tumor microenvironment landscape based on sialic acid metabolism in gastric cancer. A Comparison of tumor microenvironment scores, including stromal, immune, and ESTIMATE scores, in the SiaM clusters. These scores were determined using the ESTIMATE algorithm. Comparison of the infiltration levels of stromal (B) and immune cells (C) in the SiaM clusters. Stromal cells, including endothelial cells and fibroblasts, were quantified via the MCPcounter algorithm. The proportions of 22 types of tumor-infiltrating immune cells were estimated via the CIBERSORT algorithm. D Heatmap showing the gene expression matrix of several key immune (left panel) and stromal (right panel) components in the SiaM clusters, including ICG ligands, ICG receptors, MHC, chemokines, ECM remodeling-related genes, TGFβ response genes in CAFs, genes involved in angiogenesis, and integrins. E Comparison of transcriptional expression of the sialic acid-binding Ig-like lectin family among three SiaM clusters. The lower panel shows the cell-specific locations of the sialic acid-binding Ig-like lectin family. F Comparison of the relative levels of T-cell co-inhibition, T-cell exclusion, IFN-γ signature, and TIDE score among three SiaM clusters. These scores estimated by the TIDE algorithm represent the relative levels of immune infiltration and the potential of immunotherapy response. ICG, immune checkpoint gene; ECM, extracellular matrix; CAF, cancer-associated fibroblast; SIGLEC, sialic acid binding Ig-like lectin; TIDE, tumor immune dysfunction and exclusion. * P < 0.05; ** P < 0.01; *** P < 0.001; ns, not significant