Regulation of Nutrient Stress-Induced Macropinocytosis in Pancreatic Ductal Adenocarcinoma

项目总结 谷氨酰胺和其他氨基酸是支持代谢和生物合成反应的重要营养物质。 是维持肿瘤生长所必需的。肿瘤细胞消耗率升高可能导致肿瘤生态系统 这会耗尽营养；然而，肿瘤具有进化新陈代谢适应的能力，从而 以避开这种营养压力。一种这样的适应是刺激巨饮细胞增多，以及 在RAS转化的细胞中作为氨基酸供应途径的内吞摄取机制。通过 能够摄取细胞外蛋白并将其定位于溶酶体的降解，即巨噬细胞增多 路径为肿瘤细胞提供氨基酸，使肿瘤绕过营养耗竭而存活 营养压力。因此，阻断巨噬细胞增多代表了一种新的饥饿干预策略。 肿瘤细胞的营养物质；然而，控制和调节肿瘤中巨噬细胞吞噬的信号网络 都没有被充分理解。在这项提案中，我们将研究驱动 营养胁迫下巨噬细胞的诱导。我们的初步数据提供了第一线证据 表明谷氨酰胺耗竭引起的营养应激具有调节巨噬细胞吞噬的能力。 RAS转化的胰腺癌细胞亚群。这一点很重要，因为胰腺癌一直是 最近被认为是一种顽固性癌症，迫切需要新的治疗策略来提供 临床结果的改善。我们将营养应激诱导的巨噬细胞吞噬归因于激活 并且，重要的是，我们已经发现p53在控制这种EGFR依赖中起着关键作用 领悟。在这项提案中，我们预计破译这种可诱导形式的巨饮细胞增多是如何依赖于EGFR的。 以及这一过程是如何由来自p53的营养胁迫信号协调的。因此，我们将测试 假设胰腺肿瘤通过增强其巨噬细胞能力来应对营养应激， 由EGFR信号和P53驱动的过程。我们将：(1)确定EGFR信号的作用 谷氨酰胺耗竭诱导巨噬细胞吞噬的途径；(2)检测 (3)破译P53作为营养胁迫的功能 激活依赖于EGFR的巨噬细胞吞噬作用的传感器。这些目标将通过使用 基于细胞的体外分析、人类肿瘤询问和胰腺癌小鼠模型的组合。 综上所述，我们的工作可以将巨噬细胞吞噬建立为支持肿瘤的关键代谢适应 细胞在胰腺癌进展过程中的适应性，并为利用 肿瘤的营养依赖性。

PROJECT SUMMARY Glutamine and other amino acids are important nutrients that support the metabolic and biosynthetic reactions necessary to sustain tumor growth. Elevated consumption rates by tumor cells can lead to a tumor ecosystem that is depleted of nutrients; however, tumors have the capacity to evolve metabolic adaptations that allow them to circumvent such nutrient stress. One such adaptation is the stimulation of macropinocytosis, an endocytic uptake mechanism that functions as an amino acid supply route in Ras-transformed cells. By enabling the uptake of extracellular protein and targeting it for lysosomal degradation, the macropinocytosis pathway supplies tumor cells with amino acids, allowing tumors to circumvent nutrient depletion and survive nutrient stress. Hence, the blockade of macropinocytosis represents a novel intervention strategy to starve tumor cells of nutrients; however, the signaling networks that control and regulate macropinocytosis in tumors are insufficiently understood. In this proposal, we will investigate the molecular mechanisms that drive macropinocytic induction in response to nutrient stress. Our preliminary data provide the first lines of evidence indicating that nutrient stress elicited by glutamine depletion has the ability to modulate macropinocytosis in a subset of Ras-transformed pancreatic cancer cells. This is important because pancreatic cancer has been recently recognized as a recalcitrant cancer that is in urgent need of new therapeutic strategies that offer an improvement in clinical outcome. We have attributed nutrient stress-induced macropinocytosis to the activation of the EGFR pathway and, importantly, we have implicated p53 as critical to controlling this EGFR-dependent uptake. In this proposal, we anticipate deciphering how this inducible form of macropinocytosis relies on EGFR and how this process is orchestrated by nutrient stress signals emanating from p53. Therefore, we will test the hypothesis that pancreatic tumors cope with nutrient stress by boosting their macropinocytic capacity, a process that is driven by EGFR signaling and p53. We will: (1) Determine the role of the EGFR signaling pathway in glutamine depletion-induced macropinocytosis; (2) Examine the functional interplay between oncogenic and wild-type Ras during nutrient stress; and (3) Decipher the function of p53 as a nutrient stress sensor that activates EGFR-dependent macropinocytosis. These aims will be investigated utilizing a combination of in vitro cell-based assays, human tumor interrogation, and mouse models of pancreatic cancer. In summary, our work could establish macropinocytosis as a critical metabolic adaptation that supports tumor cell fitness during pancreatic cancer progression and set the stage for new drug discovery efforts that exploit the nutrient dependencies of tumors.