Microbial dysbiosis has been implicated in the pathogenesis of oral cancer. We analyzed the compositional and metabolic profile of the bacteriome in three specific niches in oral cancer patients along with controls using 16SrRNA sequencing (Illumina Miseq) and DADA2 software. We found major differences between patients and control subjects. Bacterial communities associated with the tumor surface and deep paired tumor tissue differed significantly. Tumor surfaces carried elevated abundances of taxa belonging to genera Porphyromonas, Enterobacteriae, Neisseria, Streptococcus and Fusobacteria, whereas Prevotella, Treponema, Sphingomonas, Meiothermus and Mycoplasma genera were significantly more abundant in deep tissue. The most abundant microbial metabolic pathways were those related to fatty-acid biosynthesis, carbon metabolism and amino-acid metabolism on the tumor surface: carbohydrate metabolism and organic polymer degradation were elevated in tumor tissues. The bacteriome of saliva from patients with oral cancer differed significantly from paired tumor tissue in terms of community structure, however remained similar at taxonomic and metabolic levels except for elevated abundances of Streptococcus, Lactobacillus and Bacteroides, and acetoin-biosynthesis, respectively. These shifts to a pro-inflammatory profile are consistent with other studies suggesting oncogenic properties. Importantly, selection of the principal source of microbial DNA is key to ensure reliable, reproducible and comparable results in microbiome studies.
Exposure to immune stress or lipopolysaccharide (LPS) during critical developmental stages like puberty may lead to gut microbiome dysbiosis and epigenetic dysregulation in mammary glands, affecting gene expression and potentially elevating breast cancer susceptibility in adulthood. Although LPS's adverse impacts on intestinal and brain functions are well-documented, its effects on mammary glands remain underexplored. Using an immunocompetent BALB/c mouse model, we administered an acute LPS dose (1.5 mg/kg body weight) during puberty. The study evaluated the long-term consequences of LPS exposure alone and combined with AHCC (Lentinula edodes cultured extract, 2 g/kg body weight/day) on DNA methylation patterns, cytokine profiles, and microRNA expression in mammary glands at 9 weeks of age. Analyses included DNA methylation sequencing, multiplex immunoassays, quantitative PCR, and image processing. Pubertal LPS exposure produced persistent molecular dysregulation in mammary glands, including differential DNA methylation (> 5% change vs. control; FDR-adjusted p < 0.05), elevated inflammatory mediators, and altered microRNA expression. Differentially methylated regions were enriched in regulatory features, with decreased methylation at transcription start sites, promoters, and 5' UTRs of genes implicated in mammary development and oncogenic signaling (including Vav3, Pdgfa, Pdgfc, Jag2, Hras, Ksr1, Il2rb, Il17b, and Il17rb) in the LPS group, whereas the AHCC + LPS group exhibited a shift toward hypermethylation at these loci (approximately 5%-10% decrease). Inflammatory profiling showed increased IL-17A/F (∼2-fold vs. control; p < 0.05), while microRNA analyses indicated reduced let-7a/c (∼30% vs. control; p < 0.05). Notably, miR-130a and miR-34a increased ∼1.5-fold across all treatment groups relative to control. Pubertal LPS exposure induces enduring epigenetic and inflammatory changes in mammary glands that may heighten breast cancer risk. AHCC's mitigating role indicates potential for dietary interventions to counteract these effects.