PR55-alpha controlled PP2A in the regulation of the Hippo/YAP pathway

PR55-α控制PP2A调节Hippo/YAP通路

• 批准号: 10693829
• 负责人: Ying Yan
• 金额: $ 30.7万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10693829
• 关键词: Anchorage-Independent Growth; Automobile Driving; Black race; CUL1 gene; Cancer Control; Cancer Etiology; Catalytic Domain; Cells; Cessation of life; Clinical; Complex; Critical Pathways; Cytoplasm; Data; Development; Disease; F-Box Proteins; Family; Genes; Holoenzymes; Human; In Vitro; KPC model; KRAS oncogenesis; KRASG12D; Knockout Mice; Knowledge acquisition; Longevity; MAP Kinase Gene; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of pancreas; Mediating; Mutation; Neoplasm Metastasis; Oncogenic; PI3K/AKT; Pancreas; Pathogenesis; Pathway interactions; Patients; Pattern; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Play; Protein Kinase; Protein Phosphatase 2A Regulatory Subunit PR53; Protein phosphatase; Proteins; Regulation; Research; Retinal blind spot; Role; Seminal; Signal Transduction; Source; Specimen; Substrate Specificity; Survival Rate; TP53 gene; Testing; Tissues; Tumor Suppression; Tumorigenicity; Work; cancer initiation; conditional knockout; defined contribution; effective therapy; improved; innovation; interdisciplinary approach; knock-down; malignant phenotype; mouse model; new therapeutic target; novel; pancreatic cancer cells; pancreatic cancer model; pancreatic cancer patients; scaffold; support network; targeted treatment; tumor progression; tumorigenesis; ubiquitin-protein ligase

Abstract Pancreatic cancer (PC) is one of the most lethal cancers in the U.S. with a 5-year survival rate of 7%, which has essentially unchanged for the past 40 years. Despite extensive research, there are no effective targeted therapies for this disease, suggesting an insufficient understanding of oncogenic signaling networks in PC. While almost all of the signaling networks implicated in cancer rely on the cooperation of kinases and phosphatases to transduce signals promoting cancer, most efforts have only been put on the study of protein kinases in cancer while leaving protein phosphatases as a blind spot. PP2A is a family of heterotrimers that serve as the main source of Ser/Thr phosphatase activities in human cells, with each consisting of a scaffold subunit (Aα/β), a catalytic subunit (Cα/β), and one of many non-conserved regulatory (B) subunits (>27) that control the substrate specificities of PP2A complexes. Our preliminary studies identified PR55α, a regulatory subunit of PP2A, as an important new player in promoting malignant PC. In particular, our studies revealed that PR55 inhibits the MOB1/LATS auto-activation loop of the Hippo tumor suppression pathway, whose function is to induce the phosphorylation of YAP causing its cytoplasmic retention and proteasomal degradation. In line with the essential role of YAP signaling in Kras-driven PC development and progression, knockdown of PR55α impeded the anchorage-independent growth, tumorigenicity, and metastasis of PC cells. Our preliminary data also revealed that the stability of PR55α protein is negatively regulated by the tumor suppressor p53 and its target gene FBXL20, a substrate adaptor for the SCF (SKP1-CUL1-F-box protein) E3 ligase. Consistently, we observed that PR55α is elevated in PC specimens, where its expression correlates with poor patient survival. Based on these findings, we hypothesize that loss of p53 function results in the stabilization of PR55α protein, which, in turn, activates the YAP oncogenic signaling required for Kras-driving PC initiation and progression. We will test the hypothesis by three specific aims: Aim 1 to define the mechanism by which PR55α/PP2A promotes YAP activation and the significance of this cascade in oncogenesis and malignant potential of PC, Aim 2 to elucidate how p53 suppresses the level of PR55α, and Aim 3 to delineate the role of the PR55/YAP axis in pancreatic cancer development and progression in the KPC spontaneous mouse model. The work is innovative, as it will illuminate a critical pathway that promotes PC initiation and progression through PR55/PP2A activated YAP signaling, which is novel to both the PP2A field and the PC field. Successful completion of the proposed studies will yield an in-depth mechanistic understanding of the critical contribution of PR55/PP2A complex to the observed cooperation between Kras activation and the loss of the p53 tumor suppressor during PC development and progression. The acquired knowledge not only will improve the understanding of the role of PP2A in cancer but also will contribute to identifying novel therapeutic targets for improving the treatment of PC.

抽象的 胰腺癌（PC）是美国最致命的癌症之一，生存率为5年，为7％，这是美国的癌症之一 在过去的40年中，本质上没有变化。尽管进行了广泛的研究，但没有有效的目标 该疾病的疗法，表明对PC中的致癌信号网络的了解不足。尽管 癌症中实施的几乎所有信号网络都依赖于激酶和磷酸酶的合作 促进癌症的转导信号，大多数努力仅在癌症中蛋白激酶的研究中投入 在将蛋白质磷酸酶留在盲点的同时。 pp2a是一个杂三聚体的家族，是主要的 人类细胞中的Ser/Thr磷酸酶活性的来源，每种都由支架亚基（Aα/β）组成 控制底物 PP2A复合物的特异性。我们的初步研究确定PP2A的调节亚基PR55α是一个 促进恶性PC的重要新玩家。特别是，我们的研究表明，PR55抑制了 河马肿瘤抑制途径的MOB1/LATS自动激活环，其功能是诱导 YAP的磷酸化导致其细胞质保留和蛋白酶体降解。与必不可少的 YAP信号传导在KRAS驱动的PC开发和进展中的作用，敲低PR55α阻碍了 PC细胞的非锚固非依赖性生长，致瘤性和转移。我们的初步数据也揭示了 PR55α蛋白的稳定性受肿瘤抑制p53及其靶基因负调节 FBXL20，一种SCF（SKP1-CUL1-F-box蛋白）E3连接酶的底物适配器。一贯，我们观察到 PC标本中的PR55α升高，其表达与患者生存不良相关。基于这些 调查结果，我们假设p53功能的丧失导致PR55α蛋白的稳定，这又是 激活KRAS驱动PC启动和进展所需的YAP致癌信号。我们将测试 假设通过三个特定目的：目标1来定义PR55α/PP2A促进YAP的机制 该级联对PC的肿瘤发生和恶性潜力的激活和意义，目标2阐明 p53如何抑制PR55α的水平，并瞄准3划定PR55/YAP轴在胰腺中的作用 KPC的赞助小鼠模型的癌症发展和进展。这项工作是创新的，因为它将 照亮了通过PR55/PP2A激活的YAP促进PC启动和进展的关键途径 信号传导，对PP2A字段和PC场都是新颖的。成功完成拟议的研究 将对PR55/PP2A复合物的关键贡献产生深入的机械理解 观察到KRAS激活与PC开发过程中p53肿瘤抑制剂的丧失之间的合作 和进展。获得的知识不仅会提高对PP2A在癌症中的作用的理解 但这也将有助于确定改善PC治疗的新型治疗靶标。