Abstract LB351: A novel mouse model to interrogate the functional relationship between protein synthesis and antigen presentation in cancer

Abstract

Abstract Antigen presentation is a fundamental component of cancer immunity. Cytotoxic CD8+ T cells, the primary mediators of cell killing, recognize peptide antigens presented in the context of Major Histocompatibility Complex Class I (MHC-I). MHC-I presents an astoundingly diverse array of peptides, collectively known as the immunopeptidome. The biosynthesis of the immunopeptidome, which integrates gene expression, protein synthesis, and proteolytic processing, is not well understood. Additionally, most studies interrogating the immunopeptidome use cultured cells in vitro, which lack physiologically relevant stimuli. In contrast, in vivo studies utilize bulk tumor or tissue lysates, in which heterogeneous cell mixtures obscure the ability to understand cell type or disease specific patterns of antigen presentation. The technical limitations have hampered our understanding of the cancer immunopeptidome in physiologically relevant tumor microenvironments in vivo. Here we present a novel genetically engineered mouse model (GEMM) of cancer, that includes KrasLox-Stop-Lox-G12D; p53fl/fl; a Cre conditionally tagged MHC-I (KbStrep), and a Cre conditionally tagged ribosome (Rpl22HA/HA), termed the “KP/RiboMHC” mouse model. The KP/RiboMHC model enables simultaneous purification of ribosomes and peptide MHC complexes to functionally interrogate translational dynamics and antigen presentation in vivo. We developed optimized workflows to perform simultaneous ribosome profiling and immunopeptidomics from lung and pancreas cancer cell lines in vitro and specifically from malignant cells in vivo. Thus, the KP/RiboMHC model provides an unprecedented opportunity to ask fundamental questions regarding the influence of physiological stimuli in the tumor microenvironment on the biosynthesis of the immunopeptidome. Insights gained using this mouse will pave the way forward for the development of context specific, peptide-centric cancer immunotherapies. Citation Format: Alex M. Jaeger, Andrew Weeden, Anika Ali. A novel mouse model to interrogate the functional relationship between protein synthesis and antigen presentation in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB351.