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Abstract Cancer‐associated fibroblasts (CAFs) are intrinsic components of the tumor microenvironment that promote cancer progression and metastasis. Through an unbiased integrated analysis of gastric tumor grade and stage, we identified a subset of proangiogenic CAFs characterized by high podoplanin (PDPN) expression, which are significantly enriched in metastatic lesions and secrete chemokine (CC‐motif) ligand 2 (CCL2). Mechanistically, PDPN(+) CAFs enhance angiogenesis by activating the AKT/NF‐κB signaling pathway. The canonical NF‐κB signaling protein P65 binds to the promoter region of CCL2, inducing its expression. Additionally, we found that CCL2 interacts with its nonclassical receptor ACKR1 (expressed on endothelial cells) to exert its proangiogenic effects. Furthermore, the disruption of CCL2‐ACKR1 communication via a CCL2 neutralizing antibody or the inhibition of AKT signaling transduction using AKT inhibitors effectively suppressed tumor growth. Together, this study elucidates the mechanism by which PDPN(+) CAFs promote angiogenesis, providing a deeper understanding of the molecular processes underlying CAF‐mediated angiogenesis and suggesting potential therapeutic targets for gastric cancer treatment.

Abstract Background Ovarian metastasis (OM) results in poor survival of gastric cancer (GC) patients. While immunotherapy has emerged as a promising approach for late‐stage GC, validated immune‐related prognostic signatures still remain in need. In this study, we constructed an ovarian metastasis‐ and immune‐related prognostic signature (OMIRPS), characterized the molecular and immune features of OMIRPS‐categorized subgroups and predicted their potential response to immunotherapy. Methods Three individual cohorts were used to construct and evaluate OMIRPS: RNA‐seq of matched primary GC and OM from Fudan University Shanghai Cancer Center (FUSCC) (discovery cohort, n = 4), The Cancer Genome Atlas (TCGA) (training cohort, n = 544) and GSE84437 (validation cohort, n = 433). Differentially expressed genes (DEGs) identified between primary GC and OM and immune‐related genes (IRGs) from the ImmPort and InnateDB databases were used to identify immune‐related prognostic hub genes, which were further used to construct OMIRPS by using LASSO regression analysis. Prognosis, molecular characteristics, immune features, and differential immunotherapy efficacy between different OMIRPS subgroups were analyzed. Results Functional analyses of DEGs revealed the significance of immune‐related signatures and pathways in the OM. Immune‐related prognostic hub genes including TNFRSF18, CARD11, BCL11B, NRP1, BNIP3L, and ATF3 were utilized to construct OMIRPS, which was identified as an independent prognostic factor. Comprehensive analyses unveiled the distinctive molecular and immune characteristics of OMIRPS‐high and ‐low subgroup in regard to enriched pathways, mutation rate, tumor mutation burden, microsatellite instability status, infiltrated immune cell, immune exclusion score, and the prediction of immunotherapy efficacy. Additionally, OMIRPS was associated with Immune Subtypes with borderline significance. Conclusions RNA‐seq of paired primary and ovarian metastatic tumors unveiled the significance of immune‐related pathways and tumor immune microenvironment in OM. OMIRPS served as a promising biomarker to predict the prognosis of GC patients and distinguish the molecular features, immune characteristics, and efficacy of immunotherapy between different subgroups.