The Macropinosome: Uncovering the Molecular Anatomy of an Oncogene-driven Organelle

项目总结 作为癌症发生的代谢重编程的一个组成部分，致癌的KRAS突变驱动 巨噬细胞吞噬作用的刺激，这是一种介导非选择性液体相摄取的吞噬作用。vbl.使用 KRAS驱动的胰腺导管腺癌(PDAC)模型，我们首次证明 巨噬细胞吞噬在肿瘤细胞中作为一种营养获取途径发挥作用。巨噬细胞增多症引发 胞外蛋白通过称为大胞体的离散内吞小泡内化。即将到来的 蛋白质货物的目标是溶酶体依赖的降解，导致细胞内氨基酸的释放。 这些蛋白质衍生的氨基酸通过对细胞内氨基酸池的贡献来支持新陈代谢健康， 以及中心碳代谢产物的生物合成。在这种情况下，巨噬细胞增多症代表了一种新的 肿瘤细胞在缺乏营养的条件下生存所使用的氨基酸供应途径 微环境。虽然在癌症中驱动巨噬细胞增多的信号转导事件的原理 尽管出现了这种现象，但目前还没有关于大管胞体体本身的详细图片。在纳米技术的帮助下，我们 已经开发出从PDAC细胞中分离出高纯度的大胞质体组分的方法学。拥有 能够提纯大胞质小体，我们现在处于独特的地位，可以从大规模蛋白质组学中受益 可以提供这个重要细胞器的概貌。通过阐明KRAS驱动的分子解剖学 我们将进一步深入了解巨噬细胞吞噬在癌症中的调节和功能。 此外，更清楚地了解大针叶小体将使我们更好地利用这一途径 在治疗方面，并为患者带来突破。

PROJECT SUMMARY As an integral aspect of the metabolic reprogramming that occurs in cancer, oncogenic KRAS mutations drive the stimulation of macropinocytosis, a type of endocytosis that mediates nonselective fluid-phase uptake. Using KRAS-driven models of pancreatic ductal adenocarcinoma (PDAC), we were the first to demonstrate that macropinocytosis functions in tumor cells as a nutrient acquisition pathway. Macropinocytosis triggers the internalization of extracellular proteins via discrete endocytic vesicles called macropinosomes. The incoming protein cargo is targeted for lysosome-dependent degradation, causing the intracellular release of amino acids. These protein-derived amino acids support metabolic fitness by contributing to the intracellular amino acid pools, as well as to the biosynthesis of central carbon metabolites. In this way, macropinocytosis represents a novel amino acid supply route that tumor cells use to survive the nutrient-poor conditions of the tumor microenvironment. While the tenets of the signal transduction events that drive macropinocytosis in cancer have emerged, a detailed picture of the macropinosome itself is not yet available. With the aid of nanotechnology, we have developed methodology to isolate a pure fraction of macropinosomes from PDAC cells. Having the capability to purify macropinosomes, we are now uniquely positioned to benefit from largescale proteomics that can provide a broad picture of this important organelle. By elucidating the molecular anatomy of KRAS-driven macropinosomes, we will gain further insight into the regulation and function of macropinocytosis in cancer. Moreover, having a clearer picture of the macropinosome will make us better positioned to exploit this pathway therapeutically and deliver breakthroughs to patients.