Compositional and functional variations of oral microbiota associated with the mutational changes in oral cancer

Both genetic and environmental factors are conceivably required to assess the prognosis of oral squamous cell carcinoma (OSCC), yet little is known regarding the relationship between oral microbiome and the mutational spectrum of OSCC.

Here, we used 16S rRNA amplicon sequencing to study the composition of oral microorganisms in OSCC patients, whose cancer mutational profiles were previously defined by whole-exome sequencing, to evaluate the relationship between oral microbiome and the mutational changes in OSCC.

Analyzing the contributions of the five mutational signatures extracted from the primary tumors revealed three groups of OSCC (mutational signature cluster, MSC1-3) that were significantly associated with demographic and clinical features. Taxonomic analysis of the predominant phyla in salivary samples showed variation in the relative abundance of Firmicutes and Bacteroidetes in the three MSC groups. In addition, significant differences in bacterial species richness (alpha diversity) and slight sample-to-sample dissimilarities in bacterial community structures (beta diversity) were noted among different MSC groups. Further, predicting the functional capabilities of microbial communities by reconstruction of unobserved states showed that many pathways related to cell motility were differentially enriched among the three MSC groups.

Collectively, these results indicate a potential association of oral microbiome with the mutational changes in OSCC.