Saliva from Oral Squamous Cell Carcinoma Patients Promotes Tumor Progression via Inflammation, Stromal Remodeling, and Metabolic Reprogramming in a Mouse Model

Background Oral squamous cell carcinoma (OSCC) is a prevalent and aggressive malignancy with increasing evidence implicating the oral microbiome and tumor microenvironment in its progression. However, the mechanistic impact of OSCC patient-derived saliva on tumor development remains poorly understood. Methods We established an orthotopic OSCC mouse model and topically applied saliva collected from OSCC patients to assess its effects on tumor progression. Multi-omics analyses, including 16S rRNA sequencing, tumor transcriptomics (RNA-seq), and metabolomics (LC-MS), were performed to explore changes in the oral microbiota, gene expression profiles, and metabolic pathways. Results Treatment with OSCC patient saliva significantly accelerated tumor growth compared to controls. Saliva application altered the oral microbiota, most notably causing a significant enrichment of the genus Staphylococcus. Tumor transcriptomics revealed upregulation of genes associated with chronic neutrophilic inflammation ( Mpo ), cancer-associated fibroblast (CAF) activation, and extracellular matrix (ECM) remodeling ( Angptl4, Col2a1 ). Metabolomic analysis demonstrated profound metabolic reprogramming within the tumors, including enhanced amino acid metabolism (tryptophan, glutamate), fatty acid oxidation, and accumulation of the oncometabolite succinate. Integrated analysis showed that Staphylococcus abundance was strongly correlated with these inflammatory and metabolic signatures. Conclusions This study demonstrates that saliva from OSCC patients promotes tumor progression in vivo through a multifactorial mechanism involving inflammation, stromal remodeling, and metabolic rewiring. These findings highlight the tumor-promoting potential of salivary and microbial components, suggesting new avenues for diagnostic and therapeutic strategies targeting the oral microenvironment in OSCC.