Potential changes in microorganisms and metabolites associated with oral cancer: a preliminary study.

BACKGROUND: Oral squamous cell carcinoma is a malignant tumor with high morbidity and mortality, and changes in microflora have a close relationship with tumor development. In this study, we tried to identify the changes in oral microbial characteristics and metabolite levels in OSCC patients. METHODS: In this study, saliva samples were collected from 40 oral cancer cases and 39 healthy controls. The microbiome was analysed by 16 S rDNA gene sequencing, and the metabolome was detected by Liquid Chromatography-Mass Spectrometry (LC-MS) with metabolite traceability using the Metorigin platform. Correlations between the microbiome and metabolome were analysed using the Spearman correlation method. RESULTS: The study found a significant difference in the beta diversity of oral microbiota between the oral cancer group and healthy controls, while alpha diversity showed no significant difference. At the phylum level, Deferribacterota significantly increased, and Cyanobacteria significantly decreased in the oral cancer group. At the genus level, Vibrio and Lactococcus were significantly elevated, while Bifidobacterium and Faecalibacterium were significantly reduced. Metabolomic analysis identified 36 differentially abundant metabolites; 13(S)-HOTrE and 13-HODE were significantly downregulated, while docosanamide was significantly upregulated in the oral cancer group. Six bacteria-specific metabolites, including Indole, were also downregulated. Correlation analysis showed that N-Acetylneuraminic acid had a significant negative correlation with Pseudoalteromonas and Vibrio (r < -0.4). CONCLUSION: This study found large differences in microbiome levels at the portal level, at the genus level, and significant differences in the levels of a variety of metabolites labeled by indoles, providing a new and potentially valuable direction for the diagnosis and treatment of oral squamous carcinoma.