Abstract Background and Aim: Gastric cancer (GC) continues to be a major global health burden, with a growing body of evidence highlighting the critical role of conventional type 1 dendritic cells (cDC1s) within the tumor microenvironment. This study aims to elucidate the prognostic significance of cDC1-associated genes—CD141, XCR1, CLEC9A, CADM1, and BTLA—in gastric cancer, as well as to explore the biological mechanisms that underpin their effects on patient outcomes. Materials and Methods: We conducted a comprehensive analysis of RNA- seq data from The Cancer Genome Atlas (TCGA-STAD) and Gene Expression Omnibus (GEO) datasets, focusing on the expression profiles of five cDC1-related genes. Patients were stratified into high and low expression groups based on a defined cDC1 gene signature. To assess the impact of these signatures, we utilized gene set variation analysis (GSVA) to examine relevant oncogenic pathways and performed Kaplan-Meier survival analysis along with Cox proportional hazards modeling to evaluate their prognostic value. Results: Our findings demonstrate that patients exhibiting a high cDC1-related gene signature had significantly worse overall and disease-free survival within the TCGA-STAD cohort. Further analysis revealed marked differences in CD8+ T cell infiltration and cytotoxic activity between the high and low cDC1 signature groups. Additionally, the high cDC1 signature group was strongly associated with upregulated expression of immune checkpoint proteins and the activation of oncogenic pathways, indicating a highly immunosuppressive tumor microenvironment. Conclusions: This study suggests that the cDC1-related gene signature may serve as a potent prognostic biomarker in gastric cancer, offering new insights into the complex interactions between the tumor and immune microenvironment. These results could pave the way for innovative therapeutic strategies that target the immune landscape in gastric cancer, potentially improving patient outcomes. Citation Format: Song-hee han. The Role of cDC1 Gene Signatures in gastric cancer prognosis and immune microenvironment modulation [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B028.
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