Exploring the interplay of endocytosis with the methionine cycle in pancreatic ductal adenocarcinoma initiation and progression.

胰腺导管腺癌(PDAC)是人类最致命的肿瘤之一。超过95%的此类肿瘤患者在确诊后5年内死亡。突变的、具有结构性活性的KrasG12D在90%的人PDAC中被激活，这导致了致癌KrasG12D是肿瘤启动所必需的假设。然而，KrasG12D下游发生的信号和细胞事件仍然知之甚少。新的证据表明，如果没有腺管上皮化生(ADM)，PDAC的发展不太可能发生。我们的初步工作表明，内吞作用在ADM发展过程中起着关键作用，蛋氨酸循环的关键酶与早期内小体相互作用。此外，我们还证明了蛋氨酸循环中的酶参与了ADM的发展，最终导致胰腺肿瘤的发生。在前期工作的基础上，我们假设在表达致癌KrasG12D的腺泡细胞中的内吞作用和蛋氨酸循环之间存在联系，从而导致ADM的发展和最终的PDAC。因此，我们打算研究以下问题：1.蛋氨酸周期的调节是否引起或抑制ADM？2.蛋氨酸周期的调节是否影响PDAC的发育？3.内吞作用和蛋氨酸周期之间是否存在联系？为了解决这些问题，我们打算使用：条件性小鼠模型；胰腺组织的三维外植体；分子和细胞生物学方法；先进的体内合成致死性筛选涉及内吞作用和蛋氨酸周期的基因。在这项研究方案中，我们试图扩大我们对蛋氨酸周期在PDAC发育中的作用的了解，特别是它与内细胞室的相互作用。我们的目标是深入了解PDAC的发展机制，并为新的诊断和/或治疗策略建立一套长期的基础知识体系。

The pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal among human tumors. More than 95% of patients with such tumors die within 5 years of diagnosis. The activation of mutated, constitutive active KrasG12D in 90% of all human PDACs has led to the hypothesis that oncogenic KrasG12D is required for tumor initiation. However, signaling and cellular events taking place downstream of KrasG12D are still poorly understood. Emerging evidence suggests that PDAC development is unlikely to occur without the preceding presence of acino-ductal metaplasia (ADM).Our preliminary work has shown that endocytosis plays a pivotal role during ADM development and that key enzymes of the methionine cycle interact with early endosomes. In addition, we have shown that enzymes that are part of the methionine cycle are involved in the development of the ADM that eventually leads to pancreatic tumor development.Based on the preliminary work, we hypothesize a link between endocytosis and the methionine cycle in acinar cells expressing oncogenic KrasG12D causing ADM development and eventually PDAC. Thus, we intend to investigate the following questions:1. Does modulation of the methionine cycle either cause or inhibit ADM? 2. Does modulation of the methionine cycle affect PDAC development?3. Is there a link between between endocytosis and the methionine cycle?To address these questions, we aim to use: conditional mouse models; three dimensional explants of pancreatic tissue; molecular and cell biological methods; an advanced in vivo synthetic lethality screening of genes involved in the endocytosis and in the methionine cycle.In this research proposal we seek to extend our knowledge of the role of the methionine cycle in PDAC development, with particular focus on its interaction with the endocytic compartment. We aim to gain insights into the mechanism of PDAC development and to establish a body of long-term basic knowledge for new diagnostic and/or therapeutic strategies.