Abstract 2020: Fatty acid metabolism supports survival in normoxia and migration upon reoxygenation in lung-metastasizing breast cancer cells.

Abstract Breast cancer is the most common cancer among women, and metastasis remains the leading cause of mortality. While fatty acid metabolism plays a critical role in cancer progression, its specific contribution to supporting breast cancer metastasis to distinct organs, particularly the lungs and liver, remains poorly understood. This study aims to characterize the lipid metabolic profiles of breast cancer cells with preferential metastasis to the lung versus the liver, and to determine how lipid metabolism supports cell survival under normoxia and drives migration upon reoxygenation after exposure to hypoxia. We utilized a unique murine breast cancer cell model with preferential metastasis to either lung (metM-WntLung; MLg) or liver (metM-WntLiver; MLr). The metastatic cells were exposed to normoxia or hypoxia (1% O2, 48 hrs) and reoxygenation to mimic dynamic tumor microenvironmental stress. Fatty acid metabolism was assessed using 13C isotopic tracing, and cell viability and migration were evaluated following inhibition of key metabolic enzymes. Results showed that 13C6-glucose and 13C5-glutamine were significantly incorporated into the synthesis of both saturated (16:0 and 18:0) and unsaturated (16:1 and 18:0) fatty acids, indicating higher de novo fatty acid synthesis in MLg cells compared to MLr cells. Despite this, both cell lines exhibited similar triacylglycerol levels without evident lipid accumulation. A pulse-chase experiment showed that 13C6-glucose-labeled fatty acids declined more rapidly in MLg than in MLr cells at 24 and 48 hrs (48.8% vs 30.3%, and 58.5% vs 48.3%, respectively), indicating more rapid fatty acid turnover in MLg than MLr cells. Inhibition of key enzymes in fatty acid metabolism, including de novo fatty acid synthesis (FASN via TVB-3166), esterification (DGAT2 via PF-06424439), lipolysis (ATGL via ATGListatin), and β-oxidation (CPT1A via etomoxir), induced a significantly greater reduction in cell viability of MLg than MLr cells, indicating that dynamic fatty acid synthesis, storage, lipolysis and oxidation are necessary to support survival in MLg cells. Under hypoxic conditions, MLg cells sustained higher de novo fatty acid synthesis accompanied by lipid accumulation. Upon reoxygenation following hypoxia, inhibition of either lipolysis or β-oxidation reduced MLg cell migration by 57% and 42%, respectively, an effect not observed in MLr cells. Overall, these results support that dynamic and rapid fatty acid turnover in lung-metastatic breast cancer cells is necessary to support survival, with lipids accumulated during hypoxia subsequently mobilized and oxidized to fuel migration upon reoxygenation. These findings identify lipid metabolism as a critical driver of lung-specific metastasis and a promising therapeutic target to reduce metastatic spread and improve outcomes for patients with breast cancer. Citation Format: Marjorie Anne Layosa, Morgan Conrad, Chaylen Jade Andolino, Michael K. Wendt, Stephen D. Hursting, Dorothy Teegarden. Fatty acid metabolism supports survival in normoxia and migration upon reoxygenation in lung-metastasizing breast cancer cells abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2020.