Porphyromonas somerae in urinary microbiome and its potential metabolic role in bladder cancer

INTRODUCTION: Recent studies on the urinary microbiome (urobiome) highlighted Porphyromonas somerae as a possible biomarker in bladder cancer (BCa). However, its functional involvement in the tumor-associated urinary microenvironment remained unexplored. In this study, the metabolic functions of the urinary microbiome of BCa patients were predicted, in order to evaluate the possible contribution of P. somerae to tumor-related microbial activity.METHODS: This study analysed 16S-rRNA gene sequencing data from 49 male subjects aged more than 50 years, divided into affected patients (BCa, N.=25) and healthy controls (HC, N.=24). Functional prediction was performed using PICRUSt and differentially abundant KEGG orthologs (KOs) were identified by DESeq2 analysis. The BCa-enriched KOs were compared with those annotated in the P. somerae genome.RESULTS: A total of 522 KOs were differentially abundant between groups, of which 129 were enriched in the BCa group. Among the latter, 15 metabolism-related KOs were also encoded by P. somerae, predicting a hypothetical involvement of the bacterium in lipid and sugar metabolism, energy production, cofactor synthesis, nucleotide and amino acid biosynthesis, and glycan metabolism.DISCUSSION: This integrative analysis suggested that P. somerae may functionally contribute to the tumour microenvironment in BCa through different metabolic pathways. This allowed us to hypothesize a possible involvement of the bacterium in proliferation, immune modulation, and tumor microenvironment remodeling. Experimental validation using metagenomic, transcriptomic, or metabolomic methods is required to confirm the PICRUSt-inferred hypotheses.