Proteasome-mediated Degradation of Hematopoietic Progenitor Kinase 1 in Pancreati

蛋白酶体介导的胰腺造血祖细胞激酶 1 的降解

• 批准号: 8113126
• 负责人: Huamin Wang
• 金额: $ 20.62万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8113126
• 关键词: Apoptosis; CUL1 gene; Cell Cycle Arrest; Cell Line; Cell Proliferation; Cells; Complex; Data; Development; Growth; Hematopoietic; Human; In Vitro; MAPK8 gene; Malignant - descriptor; Malignant Epithelial Cell; Malignant Neoplasms; Malignant neoplasm of pancreas; Mediating; Messenger RNA; Molecular; Molecular Target; Names; Neoplasm Metastasis; Oncogene Proteins; Oncogenic; Pancreatic Ductal Carcinoma; Pancreatic Intraepithelial Neoplasia; Pancreatic duct; Pathway interactions; Play; Protein-Serine-Threonine Kinases; Proteins; Regulation; Role; Sampling; Serine; System; Threonine; Time; Tumor Suppressor Proteins; Ubiquitination; Up-Regulation; Xenograft Model; cancer therapy; hematopoietic progenitor kinase 1; in vivo; insight; multicatalytic endopeptidase complex; neoplastic cell; novel; novel therapeutics; overexpression; protein degradation; protein expression; small hairpin RNA; tumor growth; tumorigenesis; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): HPK1, also named MAP4K1, is a mammalian Ste20-related serine/threonine kinase and has been shown to inhibit Erk and activate NF?B and JNK pathways (1). While a number of studies have identified the role of HPK1 in proliferation, differentiation and apoptosis in hematopoietic cells, the role of HPK1 in malignant transformation, proliferation, and invasion in malignancies has not been examined. Recently, we demonstrated that HPK1 protein is expressed in normal pancreatic ducts, but is lost in >95% of pancreatic ductal carcinoma (PDC) samples. The loss of HPK1 protein is strongly associated with the progression from low-grade pancreatic intraepithelial neoplasia (PanIN) to invasive PDC. More importantly, restoring wild type HPK1 protein expression in PDC cells resulted in cell cycle arrest and growth inhibition, which is due in part to up- regulation of p21 and p27 (2). Thus, our data showed, for the first time, that HPK1 may function as a novel tumor suppressor and its loss plays a critical role in the development of PDC. In addition, we have also demonstrated that loss of HPK1 in PDC is due to proteasome-mediated protein degradation, but not at the mRNA levels and that HPK1 kinase activity is required for the loss of HPK1 protein in PDC (2). Little is known about the regulation of HPK1 in vivo. Recently, we have identified Fbw8 as the E3 ligase that is responsible for proteasome-mediated degradation of HPK1 protein in PDC. In this proposal, we will examine the novel molecular mechanisms by which Fbw8 targets HPK1 protein for degradation and the oncogenic functions of Fbw8 in pancreatic cancer. Accomplishment of the proposed studies will not only reveal the novel molecular pathways of HPK1 regulation in pancreatic cancer, but also identify new targets for pancreatic cancer treatment. We have the following two Specific Aims: Specific Aim 1: To examine the mechanism of ubiquitin E3 ligase, Fbw8, in proteasome-mediated degradation of HPK1 protein in pancreatic cancer. Specific Aim 2: To examine the function of Fbw8-mediated HPK1 degradation in tumor growth and metastasis of pancreatic cancer. PUBLIC HEALTH RELEVANCE: Proteasome-mediated Degradation of Hematopoietic Progenitor Kinase 1 in Pancreatic Cancer We recently demonstrated that HPK1 function as a novel tumor suppressor and that proteasome-mediated degradation of HPK1 protein is strongly associated with the progression from low-grade pancreatic intraepithelial neoplasia (PanIN) to invasive pancreatic cancer. In this proposal, we will examine the detailed molecular mechanisms of proteasome-mediated degradation of HPK1 protein and to examine the possible oncogenic functions of the newly identified ubiquitin-E3 ligase, Fbw8, that is responsible for HPK1 degradation in pancreatic cancer. Accomplishment of the proposed studies will reveal novel pathways of HPK1 regulation in pancreatic cancer and identify novel targets for pancreatic cancer treatment.

描述（由申请人提供）：HPK1，也称为 MAP4K1，是一种哺乳动物 Ste20 相关丝氨酸/苏氨酸激酶，已被证明可以抑制 Erk 并激活 NFκB 和 JNK 通路 (1)。虽然许多研究已经确定了HPK1在造血细胞增殖、分化和凋亡中的作用，但HPK1在恶性肿瘤恶性转化、增殖和侵袭中的作用尚未得到检验。最近，我们证明 HPK1 蛋白在正常胰管中表达，但在 >95% 的胰腺导管癌 (PDC) 样本中丢失。 HPK1 蛋白的缺失与低度胰腺上皮内瘤变 (PanIN) 向侵袭性 PDC 的进展密切相关。更重要的是，恢复 PDC 细胞中野生型 HPK1 蛋白的表达会导致细胞周期停滞和生长抑制，部分原因是 p21 和 p27 的上调 (2)。因此，我们的数据首次表明，HPK1 可能作为一种新型肿瘤抑制因子发挥作用，并且它的缺失在 PDC 的发展中发挥着关键作用。此外，我们还证明 PDC 中 HPK1 的丢失是由于蛋白酶体介导的蛋白质降解所致，但不是在 mRNA 水平，并且 PDC 中 HPK1 蛋白的丢失需要 HPK1 激酶活性 (2)。关于 HPK1 在体内的调节知之甚少。最近，我们发现 Fbw8 是负责 PDC 中蛋白酶体介导的 HPK1 蛋白降解的 E3 连接酶。在本提案中，我们将研究 Fbw8 靶向 HPK1 蛋白降解的新分子机制以及 Fbw8 在胰腺癌中的致癌功能。该研究的完成不仅将揭示胰腺癌中 HPK1 调控的新分子途径，还将确定胰腺癌治疗的新靶点。我们有以下两个具体目标： 具体目标 1：研究泛素 E3 连接酶 Fbw8 在蛋白酶体介导的胰腺癌 HPK1 蛋白降解中的机制。具体目标2：研究Fbw8介导的HPK1降解在胰腺癌肿瘤生长和转移中的功能。 公共健康相关性：胰腺癌中蛋白酶体介导的造血祖细胞激酶 1 降解 我们最近证明 HPK1 作为一种新型肿瘤抑制因子发挥作用，并且蛋白酶体介导的 HPK1 蛋白降解与低级别胰腺上皮内瘤变 (PanIN) 发展为侵袭性胰腺癌密切相关。在本提案中，我们将研究蛋白酶体介导的 HPK1 蛋白降解的详细分子机制，并研究新鉴定的泛素 E3 连接酶 Fbw8 可能的致癌功能，该酶负责胰腺癌中 HPK1 的降解。拟议研究的完成将揭示胰腺癌中 HPK1 调节的新途径，并确定胰腺癌治疗的新靶点。