Microbial dysbiosis is evident in oral squamous cell carcinoma (OSCC) tissues of a group of Sri Lankan male patients with oral risk habits

Background Metagenomic investigations into components of the oral microbiome in a single study remain scarce. Objective To ascertain the microbiome profile of oral squamous cell carcinoma (OSCC) tissues in a group of Sri Lankan male patients. Methods From the main sample of an unmatched case-control study, a sub-sample consisting of 29 OSCC cases and 25 Fibroepithelial polyp (FEP) controls were selected. OSCC incisional and FEP excisional biopsies were collected and stored at -80 0 C. DNA was extracted from frozen specimens using Gentra Puregene Tissue kit (Qiagen, Germany), solid tissue protocol. The DNA extracts were stored at -80 0 C. Extracted DNA samples were sequenced by Illumina’s 2×300 bp chemistry. High quality non-chimeric merged reads were classified to the species level by prioritized BLASTN-algorithm for bacteriome and BLASTN-algorithm with UNITE’s named species sequences as reference for mycobiome. Results Our study identifies several potential periodontal pathogens, including Campylobacter concisus, Prevotella salivae, Prevotella loeschii , and Fusobacterium oral taxon 204 . Additionally, Candida albicans is frequently associated with oral potentially malignant disorders (OPMDs) and oral cancers. Notably, we found a significant association between Candida etchellii and oral cancer for the first time. Furthermore, Capnocytophaga, Atopobium, and Candida were the most abundant microbial genera present in oral squamous cell carcinoma (OSCC) tissues. Conclusions A dysbiotic microbiome was discovered in the tumor microenvironment of a group of OSCC male patients with oral risk habits. Validation of these biomarkers indifferent cohorts to supplement inadequacy in the diagnosis of epithelial dysplasia histologically is much warranted in the golden era of microbiome-first-medicine