Microbial metabolites in tumor epigenetic regulation

With an increasing global cancer burden, the regulatory function of the human microbiome and its metabolites in tumor epigenetics has garnered significant interest. Microbial metabolites are not merely passive byproducts but serve as signaling molecules and epigenetic modulators, contributing to tumor progression through multiple overlapping pathways. Short-chain fatty acids (SCFAs) such as butyrate directly inhibit histone deacetylases to reactivate tumor suppressor genes, while secondary bile acids (BAs) induce gene silencing via DNA methylation remodeling by altering the FXR/TGR5 signaling pathway. Folate and vitamin B12 serve as substrates for DNA and histone methylation through one-carbon metabolism. A complex bidirectional feedback loop exists between microbial metabolism and tumor epigenetics: reprogramming driven by hypoxia or oncogenes alters metabolite flux, generating molecules such as lactate and succinate that not only remodel chromatin and the tumor microenvironment (TME) but also selectively promote the growth of metabolically adapted microbial species, thereby reinforcing epigenetic dysregulation. Despite growing mechanistic insights, establishing causality and correlating spatiotemporal dynamics and dose responses within the highly heterogeneous TME remain major challenges. Data integration across multi-omics remains limited by methodological and computational constraints. Resolving these issues will be critical for understanding the microbe-metabolite-epigenetic axis and advancing personalized precision oncology.