Characterization of NACK, an essential coactivator of Notch, in tumorigenesis

描述（由申请人提供）：大量证据表明Notch基因家族在多种人类癌症中发挥作用，包括淋巴系统、胰腺、乳腺癌和中枢神经系统的肿瘤。这种转化活动是Notch的固有特性，它通过转录调控复合体介导其作用。然而，对于导致Notch转录激活复合物形成的分子事件，人们仍然缺乏足够的知识。伽马分泌酶抑制剂（GSIs）是目前临床试验中唯一针对Notch的药物。然而，异常表达的Notch细胞内结构域（NICD）对GSI治疗没有反应，因此在Notch通路中寻找适合药物靶向的新元件成为当务之急。为此，我们在Notch转录激活复合体中寻找新的组分，并鉴定出一种新的Notch相关蛋白，我们将其命名为Notch激活复合体激酶（NACK）。NACK作为Notch转录活性的共同激活因子，在人类肿瘤中表达，但在邻近的正常组织中不表达。此外，NACK是notch驱动细胞转化所必需的。我们的初步结果令人信服地确定NACK是Notch转录复合体的新成员，并且是抑制Notch通路的假定靶点。这一提议的基本假设是NAK是一种参与肿瘤发生的转录共激活因子。我们的目标是表征调控NACK功能的分子机制，确定其在肿瘤发生中的作用，并探讨将NACK作为肿瘤生物标志物和推测的抗癌药物靶点的前景。本研究的具体目的是：i)表征NACK与Notch转录调控复合物相互作用的分子基础~ ii)利用条件型NACK- ko小鼠在体内表征NACK功能~以及iii)确定NACK在Notch驱动肿瘤发生中的作用。这些研究的长期目标是全面了解NACK的功能，以便为癌症治疗的合理设计做出贡献

DESCRIPTION (provided by applicant): Substantial evidence has demonstrated a role for the Notch gene family in multiple human cancers, including neoplasms of the lymphoid system, pancreas, breast and CNS. This transforming activity is an intrinsic property of Notch, which mediates its effects through a transcriptional regulatory complex. However, there remains a significant lack of knowledge with respect to the molecular events leading to the formation of the Notch transcriptional activation complex. Gamma secretase inhibitors (GSIs) are the only drugs targeting Notch that are being tested for efficacy in clinical trials. However, aberrantly expresse Notch intracellular domain (NICD) does not respond to GSI treatment, turning into a high priority the search of new elements in the notch pathway suitable to be pharmacologically targeted. With this purpose, we have searched for new components in the Notch transcriptional activation complex and have identified a novel Notch-associated protein, we termed Notch Activation Complex Kinase (NACK). NACK functions as a co-activator of Notch transcriptional activity and it is expressed in human tumors but not in the adjacent normal tissue. Furthermore, NACK is required for Notch-driven cell transformation. Our preliminary results convincingly identify NACK as a new member of the Notch transcriptional complex and a putative target to inhibit Notch pathway. The underlying hypothesis of this proposal is that NAK is a transcriptional co-activator implicated in tumorigenesis. Our goal is to characterize th molecular mechanisms regulating NACK function, to determine its role in tumorigenesis and to investigate the prospect of using NACK as a tumor biomarker and a putative pharmacological target in anti-cancer therapies. The specific aims of this proposal are: i) Characterize the molecular basis of the interaction between NACK and the Notch transcriptional regulatory complex~ ii) Characterize NACK function in vivo using a conditional NACK-KO mouse~ and iii) Determine the role of NACK in Notch-driven tumorigenesis. The long-range goal for these studies is to obtain a comprehensive understanding of NACK function in order to contribute to the rational design of cancer therapeutics