Glutamine deprivation triggers hexosamine salvage in pancreatic cancer cells

Abstract Pancreatic ductal adenocarcinoma (PDA) remains one of the most difficult cancers to effectively treat. Over 90% of PDA are driven by oncogenic KRAS, which leads to metabolic rewiring in the cell, including increased glucose uptake and increased flux through the hexosamine biosynthesis pathway (HBP). The HBP, which branches off from glycolysis at fructose-6-phosphate and also requires glutamine, acetyl-CoA, and uridine triphosphate, is responsible for synthesizing uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), a major substrate for glycosylation in the cell. UDP-GlcNAc can also be generated through recycling of GlcNAc via N-acetylglucosamine kinase (NAGK). Glycans are important for maintaining protein homeostasis and cell signaling. However, while there is increased HBP flux in PDA and glycosylation is elevated in a range of cancers, how this is regulated and the functional significance of increased glycosylation in cancer are not well understood. Because of the multiple metabolic inputs required for UDP-GlcNAc synthesis, the HBP has been proposed as a nutrient sensing pathway. Surprisingly, however, we found that PDA cells robustly maintain both O-GlcNAc and N-glycosylation when exposed to nutrient deprivation. The enzyme N-acetylglucosamine kinase (NAGK) is upregulated under low glutamine conditions, and through stable isotope tracing studies, we demonstrate that PDA cells are able to switch to use of the salvage pathway over the HBP for generation and maintenance of the UDP-GlcNAc pool via NAGK. Together, this work points to a mechanism of metabolic flexibility in generating UDP-GlcNAC that allows PDA cells to grow in a nutrient-poor environment. Citation Format: Sydney L. Campbell, Clementina A. Mesaros, Tiffany Tsang, Michael Noji, Salisa Kruijning, Sophie Trefely, Luke Izzo, Ian A. Blair, Kathryn E. Wellen. Glutamine deprivation triggers hexosamine salvage in pancreatic cancer cells [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C10.