Cancer-associated fibroblasts (CAFs) play a central role in modulating the tumor microenvironment, but their spatial arrangement and immune-regulatory roles in Helicobacter pylori-related gastric cancer (GC) are still poorly characterized. Formalin-fixed paraffin-embedded (FFPE) tumor samples from 71 patients with GC were analyzed via spatial transcriptomics, with data integrated from single-cell RNA sequencing across three separate cohorts (originating from China, the United States, and Singapore). Interactions between CAFs and immune cells were assessed through neighborhood enrichment analysis and aggregation index scoring. CAF signaling pathways and developmental trajectories were elucidated using ligand-receptor prediction and pseudotime analysis. Post-transcriptional regulation was explored by integrating AU-rich element (ARE) motif detection, gene expression correlations, and laser-assisted crosslinking and immunoprecipitation sequencing (LACE-seq) to identify putative ZFP36 binding targets. The tumor immune composition and survival correlations were examined via CIBERSORT-ABS deconvolution and Kaplan-Meier survival curves in the TCGA and ACRG datasets.
The study initially mapped the spatial localization of four previously described CAF subpopulations and demonstrated that their links to immune components differed according to histological and infection-based GC classifications. In tumors positive for H. pylori, THBS1-expressing CAFs showed marked proximity to regulatory T cells (Tregs) and contributed to regional immune suppression via WNT5-FZD signaling. Concurrently, the RNA-binding protein ZFP36 targeted AU-rich elements in the FN1 3′ untranslated region (3'UTR), promoting FN1 mRNA degradation and consequently reducing the ability of FN1⁺ CAFs to stimulate cytotoxic T lymphocytes (CTLs). These two mechanisms collectively enhanced Treg presence while inhibiting CTL function. The results uncover infection-driven stromal mechanisms that remodel the immune milieu in gastric cancer and identify CAF-related signaling networks as promising candidates for targeted therapy in H. pylori-linked GC.
