Integrative transcriptomic and single-cell analyses reveal the critical role of GRB14 in the tumor microenvironment of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a highly aggressive malignancy characterized by pronounced molecular heterogeneity and an immunosuppressive tumor microenvironment (TME). Despite advances in multimodal therapies and immunotherapy, the overall survival of patients with OSCC remains unsatisfactory. There is an urgent need to identify robust biomarkers that integrate tumor-intrinsic signaling, stromal remodeling, and immune regulation to improve prognostic stratification and guide personalized therapeutic strategies. Growth factor receptor-bound protein 14 (GRB14) is an adaptor protein involved in receptor tyrosine kinase signaling and has been implicated in tumor progression in several malignancies; however, its role in OSCC and the tumor microenvironment has not been systematically elucidated. Publicly available transcriptomic datasets from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were utilized to comprehensively evaluate the expression patterns, prognostic value, and clinical relevance of GRB14 in OSCC. Differentially expressed genes, functional enrichment pathways, gene set variation analysis (GSVA) results, and tumor microenvironment characteristics were compared between high- and low-GRB14 expression groups. Single-cell RNA sequencing (scRNA-seq) data were analyzed to determine the cellular sources of GRB14, characterize cancer-associated fibroblast (CAF) subpopulations, and delineate intercellular communication networks. Somatic mutation profiles and tumor mutational burden (TMB) were integrated for survival analyses, and drug sensitivity prediction was performed to explore the potential therapeutic implications of GRB14. GRB14 was significantly downregulated in OSCC across multiple independent cohorts and served as an independent predictor of poor overall survival. Single-cell analyses revealed that GRB14 expression was predominantly enriched in tumor epithelial cells and fibroblasts. Low GRB14 expression was strongly associated with extracellular matrix remodeling, focal adhesion signaling, and inflammation- and stress-related pathways. Tumors with reduced GRB14 expression exhibited pronounced immunosuppressive and immune-excluded microenvironmental features, including fibroblast enrichment, reduced infiltration of cytotoxic immune cells, and impaired immune functions. Further single-cell analyses demonstrated a close association between GRB14 and specific CAF subpopulations, particularly inflammatory CAFs, which engaged in extensive paracrine interactions with other components of the tumor microenvironment. Moreover, the combined analysis of GRB14 expression and TMB provided superior prognostic stratification compared with either indicator alone. Drug sensitivity analyses suggested that GRB14 expression may be associated with differential responses to specific therapeutic strategies. This study demonstrates that GRB14 is not only a molecular biomarker for OSCC but is also closely linked to stromal activation and immune exclusion. GRB14 may function as a key molecular mediator connecting cancer-associated fibroblast remodeling with the establishment of an immunosuppressive tumor microenvironment in OSCC.