Abstract A082: Defining the lysosome proteome during pancreatic cancer tumor evolution and metastasis

Abstract Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a five-year survival rate of only 13%, characterized by rapid proliferation, high metastatic potential, and resistance to conventional therapies. PDAC tumors are heavily reliant on nutrient-scavenging pathways such as autophagy and the lysosome – a degradative organelle that plays an essential role in the digestion and recycling of diverse cellular material. Despite their importance, the specific function of lysosomes over the course of tumor evolution and metastasis in PDAC tumors remains poorly understood. To understand the function of the lysosome in PDAC, we utilize a biochemical method known as LysoIP-based proteomics, which isolates intact lysosomes for subsequent analysis using mass spectrometry-based proteomics. This approach allows for a comprehensive analysis of lysosomal composition that can uncover unique features and functions of PDAC lysosomes that promote cellular adaptation to stress in support of tumor growth. A limitation of lysosome isolation from 2D cultured cells is that it does not recapitulate lysosomal features associated with tumors growing in vivo. To address this limitation, we generated a genetically engineered mouse model of PDAC incorporating conditional expression of ‘LysoTag’ (TMEM192-mRFP-3xHA) that enables capture and profiling of lysosomes at different stages of tumor evolution, including early-stage, late-stage, and metastatic disease. Employing this strategy, we successfully captured lysosomal proteins from primary tumors (pancreas), as well as lung and liver metastases. Our preliminary analysis revealed an enrichment of resident lysosomal membrane and luminal proteins in the datasets, confirming the successful isolation of intact lysosomes from these complex tissues. Additionally, we identified non-resident lysosomal proteins (termed cargo) that are enriched and co-evolved with advancing tumor stages. Notably, our results reveal distinct differences in the lysosomal proteome of tumor cells across different tissues. These findings emphasize the critical role of lysosomal function in tumor progression and suggest that targeting lysosomal components could be a promising therapeutic strategy for treating metastatic PDAC. Citation Format: Thuy T. P Nguyen, Grace A. Hernandez, Gilles Rademaker, Matthew Luy, Alexander Li, Longhui Qiu, Joao A. Paulo, Rushika M. Perera, Joseph D. Mancias. Defining the lysosome proteome during pancreatic cancer tumor evolution and metastasis abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84 (17 Suppl₂): Abstract nr A082.