Targeting Akt with substrate mimetic antagonists

描述(由申请人提供)：各种癌症的增殖率和进展可直接与凋亡信号级联的缺陷有关。AKT是一个中心 PI3K途径中的一种蛋白，通过使细胞内底物失活来抵抗细胞凋亡。Akt的过度激活在超过50%的人类肿瘤的发生和维持中起着至关重要的作用。最常见的包括乳腺癌、卵巢癌、胰腺癌和胃癌，以及特别侵袭性的激素耐药前列腺癌。抑制Akt的激酶活性是一种经临床验证的治疗恶性肿瘤的策略。然而，大多数针对这一目标的努力都集中在取代Akt结合口袋中的内源性ATP的药物上-这一策略通常会产生抑制其他同源激酶的混杂先导化合物。相反，我们的实验室致力于Akt抑制剂的开发，这种抑制剂专门针对邻近的蛋白质底物结合裂隙。 到三磷酸腺苷站点。这种方法背后的理论基础是这样一个概念，即Akt的蛋白质-蛋白质相互作用(PPI)区域相对于其他结合位点具有更具识别力的拓扑结构。最近Akt的X射线共晶结构与其内源底物GSK3b的截断截面结合在一起，为各种多肽先导结构的设计提供了信息。虽然由于广泛的相互作用区域，靶向Akt的PPI结构域可能会更加困难，但一些引人注目的因素已促使我们寻求PPI靶向策略，包括(1)我们实验室发现了一种有效的底物模拟先导抑制剂，其多肽特性降低，(2)基于X射线结晶学的精细化的结构基础，(3)靶向Akt的广泛临床验证，以及(4)缺乏FDA批准的用于癌症治疗的Akt抑制剂。在这里，我们提出了基于结构的设计和合成基于我们的先导抑制剂的类似物的聚焦文库，并在体外和全细胞检测中对它们进行了生物学评价。本项目的目标是提供第一种能够选择性靶向Akt依赖的肿瘤细胞的非肽底物模拟抑制剂。我们的长期目标是使用PPI方法开发具有更有利治疗方案的临床候选药物，并将这一策略应用于抑制其他致癌激酶。 公共卫生相关性：AKT是一种信号蛋白，参与推动各种癌症的发生。超过50%的人类肿瘤以某种形式的Akt过度激活为特征。本研究项目致力于开发一类新型的抑制Akt的分子。这项研究的结果可能会对依赖于这一信号通路和其他激酶信号通路的恶性肿瘤的治疗具有重要意义。

DESCRIPTION (provided by applicant): The increased proliferation rate and progression of various cancers can be directly linked to defects in apoptotic signaling cascades. Akt is a central protein in the PI3K pathway that confers resistance to apoptosis through inactivation of intracellular substrates. Hyperactivation of Akt is essential in the initiation and maintenance of over 50% of all human tumors. The most common include breast, ovarian, pancreatic, and gastric cancers, as well as the particularly aggressive hormone-refractory prostate cancers. Inhibition of the kinase activity of Akt is a clinically validated strategy for the treatment of thse malignancies. However, most efforts directed toward this end focus on agents that displace endogenous ATP from the Akt binding pocket-a strategy that often yields promiscuous lead compounds that inhibit other homologous kinases. In contrast, our laboratory is engaged in the development of Akt inhibitors that specifically target the protein substrate-binding cleft adjacent to the ATP site. The rationale behind this approach is the notion that the protein-protein interaction (PPI) region of Akt harbors a far more discerning topology relative to other binding sites. Recent X- ray co-crystal structures of Akt bound to truncated sections of its endogenous substrate GSK3b have informed the design of various peptide lead structures. Although targeting the PPI domain of Akt is presumably more difficult due to the extensive interaction region, a number of compelling factors have prompted us to pursue a PPI-targeting strategy, including (1) the discovery, in our lab, of a potent substrate mimetic lead inhibitor with reduced peptide character, (2) a structural rationale for refinements based on X-ray crystallography, (3) extensive clinical validation for targeting Akt, and (4) the lack of an FDA-approved Akt inhibitor for the treatment of cancer. Here, we propose the structure-based design and synthesis of a focused library of analogs based on our lead inhibitor, and their biological evaluation in vitro an in whole cell assays. The objective of this project is to provide the first non-peptide substrate mimetic inhibitors capable of selectively targeting Akt-dependant tumor cells. Our longer-term goals are to use a PPI approach to develop clinical candidates with more favorable therapeutic profiles and to apply this strategy to the inhibition of other oncogenic kinases. PUBLIC HEALTH RELEVANCE: Akt is a signaling protein involved in driving the onset of various cancers. Greater than 50% of all human tumors feature some form of Akt hyperactivation. This research project is focused on the development a new class of molecules to inhibit Akt. Results from this study will potentially have important implications for the treatment of malignancies dependant on this and other kinase signaling pathways.