SIRT6 and hepatocellular carcinoma: While the roles of SIRT5, SIRT6, and SIRT7 in gut microbiota regulation are not directly established, it is notable that downregulation of SIRT5 has been linked to increased bile acid production, which may contribute to an immunosuppressive tumour microenvironment and facilitate hepatocellular carcinoma (HCC) development [116].