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

描述（由申请方提供）：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、乳腺和CNS肿瘤。 这种转化活性是Notch的固有特性，其通过转录调节复合物介导其作用。然而，对于导致Notch转录激活复合物形成的分子事件，仍然存在显著的知识缺乏。 γ分泌酶抑制剂（GSI）是唯一正在临床试验中测试疗效的靶向Notch的药物。然而，异常表达的Notch胞内结构域（NICD）对GSI治疗没有反应，因此在Notch通路中寻找适合于靶向GSI的新元件成为高度优先事项。为此，我们已经在Notch转录激活复合物中寻找新的组分，并鉴定了一种新的Notch相关蛋白，我们称之为Notch激活复合物激酶（NACK）。 NACK作为Notch转录活性的共激活因子起作用，并且其在人肿瘤中表达，但不在邻近的正常组织中表达。此外，Notch驱动的细胞转化需要NACK。我们的初步结果令人信服地确定NACK作为一个新的成员的Notch转录复合物和一个假定的目标，以抑制Notch途径。 该提议的基本假设是，NAK是与肿瘤发生有关的转录共激活因子。本研究的目的是探讨NACK的分子调控机制，确定其在肿瘤发生中的作用，并探讨NACK作为肿瘤生物标志物和抗癌药物靶点的前景。该提议的具体目的是：i）表征NACK和Notch转录调控复合物之间相互作用的分子基础，ii）使用条件性NACK-KO小鼠表征NACK的体内功能，以及iii）确定NACK在Notch驱动的肿瘤发生中的作用。 这些研究的长期目标是获得对NACK功能的全面了解，以便有助于癌症治疗的合理设计

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