Abstract 5397: Role of pyruvate carboxylase in cancer-associated fibroblasts under tumor nutrient stress

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and hard-to-treat cancer types. PDAC is characterized by desmoplastic stroma enriched with extracellular matrix (ECM), immune cells and cancer-associated fibroblasts (CAFs). CAFs modulate PDAC progression by producing ECM and signaling molecules that influence cancer and immune cell function. Previous efforts to target CAFs’ role in PDAC were unsuccessful but have instead revealed substantial heterogeneity within the CAF population. Two main subtypes of CAFs are tumor-restraining myofibroblastic CAFs (myCAFs) and tumor-promoting inflammatory CAFs (iCAFs). To effectively target CAFs in PDAC, there is a need to find CAF-state-specific vulnerabilities and mechanisms regulating CAF state. We discovered that myCAFs are excluded from hypoxic and nutrient-stressed regions of PDAC, and iCAFs are selectively enriched in those regions. Pyruvate carboxylase (PC) is an enzyme that allows cells to utilize pyruvate as an anaplerotic substrate. Our previous work showed that PC is important for CAFs under nutrient-stressed conditions. Here, we hypothesize that PC is required to promote the iCAF state and support their growth in the nutrient-stressed environments they occupy. To address this hypothesis, we acclimated pancreatic stellate cells (PSCs), CAF precursors in PDAC, to physiological media resembling the concentration of nutrients in human plasma (HPLM - human plasma-like medium) or PDAC (TIFM - tumor interstitial fluid medium). We used CRISPR/Cas9 to delete PC, allowing us to investigate the role of PC in PSCs under physiological conditions. We observed that PC expression is higher in cells cultured in TIFM than in HPLM or conventional RPMI. We confirmed higher PC activity in TIFM compared to HPLM or RPMI cultured cells using stable isotope tracing. These findings indicate that PC expression and activity are regulated by the nutrient conditions present in PDAC and suggest that PC might be selectively important in CAFs under tumor nutrient stress. A better understanding of PC’s role in CAFs residing in nutrient-stressed niches in PDAC may lead to the discovery of a novel way of targeting tumor-promoting iCAFs. Citation Format: Michał Nizio, Marta Storl-Desmond, Kevin Muñoz Forti, Julien Guillard, Shan Cao, Kristof Turan, Alexander Muir, Simon Schwörer. Role of pyruvate carboxylase in cancer-associated fibroblasts under tumor nutrient stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5397.