Core Viewpoint - The article discusses the role of the gut microbiome, specifically the bacterium Catenibacterium mitsuokai, in promoting hepatocellular carcinoma (HCC) through mechanisms involving gut barrier disruption and metabolic product secretion [2][3][5]. Group 1: Research Findings - A new carcinogenic gut bacterium, Catenibacterium mitsuokai, has been identified, which promotes the development of HCC by binding to hepatocytes and generating quinolinic acid [3][6]. - Catenibacterium mitsuokai is enriched in the feces and tumors of HCC patients, and it accelerates the carcinogenesis process in both conventional and germ-free mice [5][10]. - The bacterium disrupts the gut barrier and transfers to the liver, where it adheres to HCC cells via the interaction of its surface protein Gtr1/RagA with the γ-catenin receptor on cancer cells [6][10]. Group 2: Mechanistic Insights - The tumor-promoting effect of Catenibacterium mitsuokai is dependent on its secretion of the metabolite quinolinic acid [6][9]. - Quinolinic acid binds to the TIE2 receptor on HCC cells, activating the downstream oncogenic PI3K/AKT pathway, thereby facilitating the progression of liver cancer [6][9].