Targeting the PI3K/AKT pathway in cancer using a pan-AKT degrader

摘要 丝氨酸/苏氨酸激酶AKT是磷脂酰肌醇3-激酶(PI3K)信号的中心组成部分 它是细胞生长、增殖和新陈代谢等多种细胞过程的关键调节因子。 PI3K/AKT通路的异常激活扰乱了正常的增殖和生存调节，导致 肿瘤发生学。AKT在超过50%的人类肿瘤中高度激活，使其成为最常见的分子之一 癌症中的微扰。几种ATP竞争性、变构和共价的PAN-AKT抑制剂已经被 已经开发，目前正在进行临床研究。然而，对AKT抑制的强烈治疗反应 都没有被观察到。我们假设通过靶向蛋白降低细胞AKT蛋白水平 降解可以增强对依赖AKT信号的细胞的杀伤能力。异型双功能降解剂 分子，也被称为PROTACs(蛋白水解靶向嵌合体)，招募E3泛素连接酶进入 接近目标蛋白以诱导其泛素化和随后的蛋白酶体降解。我们 开发的INY-03-041，一种由AKT抑制剂GDC-0068化学偶联组成的PAN-AKT降解剂 E3泛素连接酶Cereblon的招聘人员来那度胺。蛋白质降解剂显示出几个优点 过多的抑制剂，包括提高多靶点抑制剂的选择性，取消不依赖于激酶的 功能，并克服抗药性突变。INY-03-041可诱导所有细菌的有效和选择性降解 三种AKT亚型，与GDC-0068相比，在乳腺癌中显示出更强的抗增殖作用 细胞。驱动这一应用的假设是，靶向AKT降解将更多地抑制癌细胞生长 强于AKT抑制，导致体内持久反应，并将是一种有价值的工具，以确定新的 AKT的生物学功能。在目标1中，我将评估INY-03-041介导的AKT降解的后果 对细胞信号、增殖和存活的影响。这一目标的目的是揭示AKT在急性发作后的新功能。 蛋白质耗竭，并确定对AKT降解的敏感性的遗传或表观遗传生物标志物，这可能 告知AKT降解的治疗适应症。在目标2中，我将研究INY-03-041诱导的AKT 体内降解以确定AKT耗竭是否可能是一种可行的治疗方式。总而言之，这项提案 目的是研究AKT降解的功能后果，并使用INY-03-041作为化学探针 目的：研究急性AKT耗竭的影响。拟议的研究不仅是基于发现的，而且突出了 解码控制人类癌症AKT信号转导的多效性机制的新方法。

Abstract The serine/threonine kinase AKT is a central component of the phosphoinositide 3-kinase (PI3K) signaling pathway and a key regulator of many cellular processes including cell growth, proliferation, and metabolism. Aberrant activation of the PI3K/AKT pathway disrupts normal regulation of proliferation and survival, resulting in tumorigenesis. AKT is hyperactivated in over 50% of human tumors, making it one of the most frequent molecular perturbations in cancer. Several ATP-competitive, allosteric, and covalent pan-AKT inhibitors have been developed and are currently under clinical investigation. However, robust therapeutic responses to AKT inhibition have not been observed. We hypothesized that reducing cellular AKT protein levels via targeted protein degradation could enhance the ability to kill cells dependent on AKT signaling. Heterobifunctional degrader molecules, also known as a PROTACs (proteolysis targeting chimeras), recruit an E3 ubiquitin ligase into close proximity with the target protein to induce its ubiquitination and subsequent proteasomal degradation. We developed INY-03-041, a pan-AKT degrader consisting of the AKT inhibitor, GDC-0068, chemically conjugated to lenalidomide, a recruiter of the E3 ubiquitin ligase Cereblon. Protein degraders display several advantages over inhibitors, including enhancing selectivity of multi-targeted inhibitors, abrogating kinase-independent functions, and overcoming resistance mutations. INY-03-041 induces potent and selective degradation of all three AKT isoforms, and exhibits enhanced anti-proliferative effects compared to GDC-0068 in breast cancer cells. The hypothesis driving this application is that targeted AKT degradation will inhibit cancer cell growth more robustly than AKT inhibition, leading to durable responses in vivo, and will be a valuable tool to identify novel biological functions of AKT. In Aim 1 I will evaluate the consequences of INY-03-041-mediated AKT degradation on cell signaling, proliferation, and survival. The goal of this aim is to uncover novel functions of AKT after acute protein depletion, and to identify genetic or epigenetic biomarkers for sensitivity to AKT degradation, which may inform therapeutic indications for AKT degradation. In Aim 2 I will investigate INY-03-041-induced AKT degradation in vivo to determine if AKT depletion may be a viable therapeutic modality. In summary, this proposal aims to investigate the functional consequences of AKT degradation, and to use INY-03-041 as a chemical probe to study the effects of acute AKT depletion. The proposed studies are not only discovery-based, but highlight a novel method to decode the pleiotropic mechanisms that govern AKT signaling in human cancer.