FCGR2A as a New Potential Prognostic Biomarker of Esophageal Squamous Cell Carcinoma
Esophageal squamous cell carcinoma (ESCC) is a highly aggressive malignancy associated with significant morbidity and mortality. Despite advancements in therapeutic strategies, the prognosis for ESCC patients remains poor, underscoring the urgent need for reliable prognostic biomarkers and molecular targets. This study investigates the role of Fc fragment of immunoglobulin G receptor IIa (FCGR2A) as a novel prognostic biomarker in ESCC, leveraging multi-omics data and bioinformatics tools to unravel its clinical relevance and mechanistic implications.
Identification of Differentially Expressed Genes in ESCC
The study utilized RNA sequencing datasets from the Gene Expression Omnibus (GEO) database (GSE130078 and GSE149609), comprising 33 ESCC tissues and 33 adjacent normal tissues. Differential expression analysis via DESeq2 identified 3,885 and 3,477 differentially expressed genes (DEGs) in GSE130078 and GSE149609, respectively, under thresholds of |log2 Fold-Change| ≥1 and adjusted P <0.05. A comparative analysis revealed 1,914 overlapping DEGs between the two datasets. These overlapping genes were prioritized for subsequent protein-protein interaction (PPI) network analysis to identify hub genes critical to ESCC pathogenesis.
PPI Network Construction and Hub Gene Selection
Using the STRING database and Cytoscape software, a PPI network was constructed for the 1,914 DEGs. Molecular Complex Detection (MCODE) analysis identified the top functional module (MCODE score =29.156), comprising 46 hub genes. FCGR2A emerged as a central node with a node degree of 19.863, suggesting its pivotal role in maintaining network integrity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that these hub genes were predominantly associated with cytokine-cytokine receptor interactions, interleukin (IL)-17 signaling, and chemokine signaling pathways—all implicated in cancer progression and survival.
Validation of Hub Genes in Independent Cohorts
The expression of the 46 hub genes was validated using data from The Cancer Genome Atlas (TCGA) and Genotype Tissue Expression (GTEx) databases, encompassing 182 ESCC tissues and 286 normal tissues. Only 23 genes, including FCGR2A, exhibited significantly elevated expression in tumor tissues (P <0.05). Among these, FCGR2A showed the most pronounced upregulation in ESCC (Figure 1A).
Prognostic Significance of FCGR2A in ESCC
Survival analysis using TCGA data evaluated the impact of the 23 validated hub genes on disease-free survival (DFS). Cox proportional hazards models revealed that high expression of FCGR2A (hazard ratio [HR]=1.700, 95% confidence interval [CI]:1.110–7.605, P=0.032), fibronectin 1 (FN1; HR=2.000, 95% CI:1.663–5.368, P=0.007), and secreted phosphoprotein 1 (SPP1; HR=2.300, 95% CI:2.150–3.796, P=0.001) correlated with significantly worse DFS (Figure 1B). Notably, FCGR2A expression increased progressively with advanced clinical stages (stages II–IV vs. stage I; F=2.980, P=0.033) (Figure 1C), reinforcing its role as a stage-dependent prognostic marker.
FCGR2A and Immune Microenvironment in ESCC
Gene Ontology (GO) analysis via KOBAS linked FCGR2A to immune response pathways. To explore this association, tumor-infiltrating immune cell (TIIC) profiles were analyzed using the Tumor Immune Estimation Resource (TIMER) database. FCGR2A expression exhibited the strongest positive correlation with macrophage infiltration (R=0.656, P<0.001) (Figure 1D). Further stratification revealed that FCGR2A correlated specifically with M2 macrophages—a pro-tumorigenic subtype—as evidenced by strong associations with M2 markers CD163 (R=0.831, P<0.001), VSIG4 (R=0.817, P<0.001), and MS4A4A (R=0.849, P<0.001) (Figure 1E). In contrast, no significant correlation was observed with M1 macrophage markers like nitric oxide synthase 2 (NOS2) or interferon regulatory factor 5 (IRF5) (Figure 1F).
FCGR2A also showed robust correlations with tumor-associated macrophage (TAM) markers, including C-C motif chemokine ligand 2 (CCL2; R=0.609, P<0.001), CD68 (R=0.433, P<0.001), and IL-10 (R=0.567, P<0.001) (Figure 1G). Importantly, FCGR2A expression strongly aligned with CD204 (R=0.855, P<0.001), a marker linked to TAM-mediated immunosuppression and poor prognosis in ESCC (Figure 1H). These findings position FCGR2A as a regulator of immune evasion, potentially driving ESCC progression through M2 macrophage polarization and TAM recruitment.
Mechanistic Implications and Clinical Relevance
The study highlights FCGR2A’s dual role as a prognostic biomarker and immune modulator in ESCC. Its overexpression correlates with advanced disease stages and immunosuppressive macrophage infiltration, both hallmarks of aggressive tumor behavior. The IL-17 and chemokine signaling pathways—enriched among hub genes—further implicate FCGR2A in cytokine-driven tumor inflammation and metastasis. While the exact mechanisms remain to be elucidated, FCGR2A may enhance macrophage-dependent immune suppression by engaging IgG immune complexes or promoting phagocytic clearance of antibody-opsonized tumor cells.
Limitations and Future Directions
Despite its bioinformatics rigor, the study lacks experimental validation of FCGR2A’s functional role in ESCC. Future work should include in vitro and in vivo models to confirm FCGR2A’s impact on macrophage polarization and tumor progression. Additionally, prospective clinical cohorts are needed to validate FCGR2A’s prognostic utility and explore its potential as a therapeutic target.
Conclusion
This integrative analysis identifies FCGR2A as a novel prognostic biomarker in ESCC, with high expression predicting poor survival and advanced disease. Its association with M2 macrophages and TAMs underscores the interplay between tumor cells and the immune microenvironment, offering new avenues for immunotherapy strategies. By bridging genomic insights with immune profiling, this study advances our understanding of ESCC biology and paves the way for personalized prognostic tools.
doi.org/10.1097/CM9.0000000000001776
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