Pancreatic ductal adenocarcinoma (PDA) is a lethal, therapy-resistant cancer that thrives in a highly desmoplastic, nutrient-deprived microenvironment. Several studies investigated the effects of depriving PDA of either glucose or glutamine alone. However, the consequences on PDA growth and metabolism of limiting both preferred nutrients have remained largely unknown. Here, we report the selection for clonal human PDA cells that survive and adapt to limiting levels of both glucose and glutamine. We find that adapted clones exhibit increased growth in vitro and enhanced tumor-forming capacity in vivo. Mechanistically, adapted clones share common transcriptional and metabolic programs, including amino acid use for de novo glutamine and nucleotide synthesis. They also display enhanced mTORC1 activity that prevents the proteasomal degradation of glutamine synthetase (GS), the rate-limiting enzyme for glutamine synthesis. This phenotype is notably reversible, with PDA cells acquiring alterations in open chromatin upon adaptation. Silencing of GS suppresses the enhanced growth of adapted cells and mitigates tumor growth. These findings identify nongenetic adaptations to nutrient deprivation in PDA and highlight GS as a dependency that could be targeted therapeutically in pancreatic cancer patients.

胰腺导管腺癌 (PDA) 是一种致命的、难治性的癌症，在高度促纤维增生、营养匮乏的微环境中生长。几项研究调查了单独剥夺 PDA 葡萄糖或谷氨酰胺的影响。然而，限制这两种首选营养物质对 PDA 生长和代谢的影响仍然很大程度上未知。在这里，我们报告了对能够存活并适应葡萄糖和谷氨酰胺限制水平的克隆人 PDA 细胞的选择。我们发现适应的克隆表现出体外生长增加和体内肿瘤形成能力增强。从机制上讲，适应的克隆具有共同的转录和代谢程序，包括用于从头谷氨酰胺和核苷酸合成的氨基酸。它们还表现出增强的 mTORC1 活性，可防止谷氨酰胺合成酶 (GS)（谷氨酰胺合成的限速酶）的蛋白酶体降解。这种表型明显是可逆的，PDA 细胞在适应后开放染色质会发生改变。GS 沉默会抑制适应细胞的增强生长并减轻肿瘤生长。这些发现确定了 PDA 对营养缺乏的非遗传适应，并强调 GS 作为一种依赖性，可以作为胰腺癌患者的治疗目标。