Composition and function of oral microbiota between gingival squamous cell carcinoma and periodontitis

Objectives: Previous studies have proved that periodontitis is an independent risk factor of oral squamous cell carcinoma (OSCC) epidemiologically. Along with the important role of microbiota in the cancer process and the specific anatomical position, our study explored the microbial composition and functions in periodontitis and gingival squamous cell carcinoma (GSCC). Materials and Methods: GSCC patients (n = 10), matched periodontitis patients (n = 15), and healthy individuals (n = 15) were recruited. Saliva, subgingival plaque, tongue dorsum, buccal mucosa, cancerous tissue, and paracancerous tissue samples were collected. 16S rDNA amplicon sequencing and functional prediction were applied for the taxonomic analysis. Results: Periodontal pathogens occupied 46% in GSCC. Besides, the mutual operational taxonomy unites (OTU) generated from the subgingival plaque occupied 38.36% and 44.13% from saliva. Fusobacterium, Peptostreptococcus, and Prevotella were more abundant in cancerous tissues, while Streptococcus, Neisseria, and Haemophilus were more enriched in saliva or soft mucosa. PCoA exhibited similar cluster between tongue dorsum and saliva in GSCC. GSCC showed lower richness than periodontitis. In saliva and subgingival plaque, Atopobium was more prevalent in GSCC than periodontitis and controls in descending order. Lipopolysaccharide (LPS) biosynthesis increased in subgingival plaque of GSCC compared with the other two groups. Conclusion: Periodontal pathogens were abundant in GSCC. Cancerous tissues harbor enriched periodontal pathogens while saliva or soft mucosa harbored more periodontal health related bacteria. A high level of Atopobium in saliva and LPS biosynthesis have the potential for increasing the risk of suffering from GSCC in individuals with periodontitis, which needs more evidence to clarify it.