Abstract 3974: Macronutrient composition dictates MASH-associated HCC immunosurveillance through microbiota alteration and metabolic adaptation

Abstract Hepatocellular carcinoma (HCC) is the most common form of liver cancer, with an estimated incidence of over one million cases by 2025. The advances in vaccines against HBV and HCV have led to a decrease in the number of virus-related cases; however, the obesity epidemic has contributed to a drastic increase in metabolic dysfunction-associated steatohepatitis (MASH) related HCC cases (e. g. , obesity and type 2 diabetes induced HCC). Considering this trend, we aim to understand how lifestyle choices, like food composition, in combination with alcohol consumption at a “social drinking level” impacts host metabolism, and subsequently the development of MASH-induced HCC. We hypothesize that the impact of dietary composition on dysbiosis and immune cells, particularly adaptive immune cell metabolic status, will drive the phenotype. We have developed a MASH-induced HCC murine model, with long-term dietary intervention including seven different customized diets: normal chow (NC), ketogenic, solid high fat diet (sHFD), or isocaloric liquid Lieber DeCarli Diets (LDC): high fat/low carb (HF), high fat/low carb with ethanol (HF-EtOH), low fat/high carb (LF), and low fat/high carb with ethanol (LF-EtOH). Mice began special diet in late adolescences and disease progression was monitored over the course of a year, where mice developed HCC. Our model allowed for a comprehensive understanding of MASH-induced HCC where disease initiation could be studied beyond known contributors like obesity or body mass index (BMI). The animal model was analyzed comprehensively with high-parameter flow cytometry (FC), 16S sequencing, bulk RNA-seq, scRNA/ATAC-seq, and WGS. Long-term diet intervention led to macronutrient specific microbiota dysregulation, alterations in systemic metabolism and suppression of adaptive immune response, consequently impacting the progression of HCC. Customized dietary interventions showed a specific phenotype regarding HCC development and progression with distinct mutational genotype and particular response to immunotherapy. T and B cell subpopulation deficiency had a significant impact on MASH-induced HCC development in a macronutrient composition dependent manner. In summary, each dietary intervention showed a distinct pattern and effect on dysbiosis, systemic metabolic reprograming, cellular transcriptomic and epigenetic alteration, and particularly immune cell effector function. Additionally, some compositions supported the immuno-escape mechanism of malignant cells through regulation of their MHC machinery. Collectively, these accumulated data construct an atlas for understanding the underlying molecular mechanisms contributing to lifestyle-induced HCC providing the knowledge needed to advance effective strategies for treatment and prevention. Citation Format: Nicolas T. Ryujin, Jian Huang, Albert Nguyen, Jared Edwards, Yuhe Cheng, Jessica Wen, Ashish Damania, Nadim Ajami, Spencer Rosario, Mark Long, Ludmil Alexandrov, Shabnam Shalapour. Macronutrient composition dictates MASH-associated HCC immunosurveillance through microbiota alteration and metabolic adaptation abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3974.