fig3

Figure 3. The proposed mechanisms of intratumoral microbiota promoting HCC by affecting host epigenetic regulation. Intratumoral microbiota affects host epigenetic regulation mainly through two pathways. Pathway A: Intratumoral microbiota secretes SCFAs (e.g., butyrate), which inhibit HDAC and increase histone acetylation, leading to altered gene expression in the HCC cell nucleus, resulting in tumorigenesis. Pathway B: Intratumoral microbial activity alters bile acid metabolism, which modulates DNMT function and leads to hypermethylation or hypomethylation of DNA, further altering gene expression, resulting in tumorigenesis. HCC: Hepatocellular carcinoma; SCFAs: short-chain fatty acids; HDAC: histone deacetylase; DNMT: DNA methyltransferase.