Mast Cells Drive Ferroptosis in Gastric Tumors as Key Players in the Tumor Immune Microenvironment.

Ferroptosis, an iron-dependent form of oxidative cell death, plays a critical role in cancer progression and immune regulation. However, the functional connections of ferroptosis with specific immune cell types remain poorly defined, limiting the future possibilities to harness ferroptosis for cancer biology, diagnosis, and treatment. To address this knowledge gap, we conducted an integrated transcriptomic analysis to investigate ferroptosis-related immune dynamics in gastric cancer (GC). We utilized GC datasets from The Cancer Genome Atlas-stomach adenocarcinoma ( = 412) and the GSE66229 ( = 300) that were clustered into three GC immune subtypes based on single-sample Gene Set Enrichment Analysis scores of 29 immune gene sets. Bulk RNA-seq analysis revealed that the immune-inflamed subtype (HIS) of tumor samples in both GC datasets exhibited the highest ferroptosis enrichment and showed a positive correlation with activated mast cells and neutrophils. Given the regulatory role of mast cells in the tumor microenvironment (TME), particularly in recruiting neutrophils, we further examined their link to ferroptosis. In a fibroblast-mast cell coculture RNA-seq data (GSE223179), fibroblasts exhibited increased ferroptosis enrichment, supporting a mast cell-mediated influence. Single-cell RNA-seq data confirmed stronger interactions between mast cells and fibroblasts in GC compared to normal tissues. Specifically, they revealed a positive correlation between mast cell activity and ferroptosis enrichment in tumor-associated fibroblasts. In conclusion, these findings suggest that mast cells may promote ferroptosis in the TME through paracrine signaling, possibly via annexin and cyclophilin A. By uncovering this novel pathophysiological axis, our study reveals a previously unrecognized role of mast cells in regulating ferroptosis within the TME. The findings call for translational and experimental medical research and have potential implications for innovation toward GC diagnostics and therapeutics.