Selectively Targeting Oncogenic NRAS in Cancer

具体目标 致癌性RAS突变是癌症中最常见的分子改变之一， 主要驱动异常生长的突变蛋白质。不幸的是， 突变型Ras/GTP酶激活蛋白（Ras/GAP）分子开关对 基于机制的药物发现和没有靶向治疗已被批准用于Ras驱动的癌症， 约会Ras棕榈酰化/脱棕榈酰化循环调节N-Ras、H-Ras、 和K-Ras 4a同种型，但不是K-Ras 4 b。因此，开发有效的和选择性的Ras抑制剂， 棕榈酰化/去棕榈酰化循环具有治疗依赖致癌N-Ras的恶性肿瘤的潜力 而不干扰正常组织中的K-Ras 4 b信号传导。这个正在进行的项目涉及跨学科 具有生物化学，化学生物学， 血液癌症、Ras信号传导和临床前治疗。在本财政年度，我们：（1） 验证了N-Ras棕榈酰化作为NRAS突变型癌症的有希望的治疗靶点， NrasG 12 D、C181 S“敲入”小鼠;（2）将丝氨酸水解酶（SH）的ABHD 17家族鉴定为N-Ras （3）表明帕莫司他丁类SH抑制剂过于混杂，不能用作 ABHD 17功能的选择性探针;（4）与Lundbeck合作，确定了一个结构独特的类别 选择性ABHD 17抑制剂，减少NRAS突变型急性髓性白血病（AML）细胞的生长 并在等基因模型中表现出基因型特异性活性;（5）证明NRAS的生长减少 ABHD 17受体处理的突变AML细胞与Ras效应子的生化抑制相关 途径。这项更新申请中提出的实验将通过以下方式扩展这些令人兴奋的研究： 具体目标：目标1。研究ABHD 17 s和其他SH酶在N-Ras中的作用 并在临床前模型中测试有效的和生物可利用的ABHD 17抑制剂ABD 778。 AML;以及，目标2。鉴定修饰N-Ras的棕榈酰酰基转移酶（PAT）蛋白并验证它们 作为N-Ras突变型癌症的靶点。我们预计，在这个跨学科项目中描述的研究 将确定N-Ras棕榈酰化的基本机制，确定 ABHD 17的化学抑制剂单独和与其他靶向药物组合的作用，并产生 开发PAT抑制剂作为抗癌药物的必要基础知识。的发展 致癌N-Ras信号传导的选择性抑制剂将对许多肿瘤具有显著的治疗作用。 不同的侵袭性成人和儿童癌症。

SPECIFIC AIMS Oncogenic RAS mutations, which are among the most common molecular alterations in cancer, encode mutant proteins that dominantly drive aberrant growth. Unfortunately, structural and biochemical properties of the mutant Ras/GTPase activating protein (Ras/GAP) molecular switch pose formidable barriers to mechanism-based drug discovery and no targeted therapies have been approved for Ras-driven cancers to date. The Ras palmitoylation/depalmitoylation cycle regulates the subcellular trafficking of the N-Ras, H-Ras, and K-Ras4a isoforms, but not of K-Ras4b. Thus, developing potent and selective inhibitors of the Ras palmitoylation/depalmitoylation cycle has the potential to treat malignancies dependent on oncogenic N-Ras without interfering with K-Ras4b signaling in normal tissues. This ongoing project involves a cross-disciplinary collaboration between investigators with complementery expertise in biochemistry, chemical biology, hematologic cancer, Ras signaling, and preclinical therapeutics. During the current funding period we: (1) validated N-Ras palmitoylation as a promising therapeutic target for NRAS mutant cancers in a novel strain of NrasG12D,C181S “knock in” mice; (2) identified the ABHD17 family of serine hydrolase (SH) enzymes as N-Ras depalmitoylases; (3) showed that the Palmostatin class of SH inhibitors are too promiscuous for use as selective probes of ABHD17 function; (4) identified, in collaboration with Lundbeck, a structurally distinct class of selective ABHD17 inhibitors that reduce the growth of NRAS mutant acute myeloid leukemia (AML) cells and exhibit genotype-specific activity in isogenic models; and, (5) demonstrated that reduced growth of NRAS mutant AML cells treated with ABHD17 inhibigtors correlates with biochemical inhibition of Ras effector pathways. The experiments proposed in this renewal application will extend these exciting studies through the following specific aims: Aim 1. To investigate the roles of ABHD17s and additional SH enzymes in N-Ras depalmitoylation and to test the potent and bioavailable ABHD17 inhibitor ABD778 in preclinical models of AML; and, Aim 2. To identify palmitoyl acyl transferase (PAT) proteins that modify N-Ras and to validate them as targets for N-Ras mutant cancers. We anticipate that the studies described in this interdisciplinary project will determine fundamental mechanisms of N-Ras palmitoylation, ascertain the efficacy and mechanism of action of chemical inhibitors of ABHD17s alone and in combination with other targeted agents, and generate essential foundational knowledge for developing PAT inhibitors as anti-cancer drugs. The development of selective inhibitors of oncogenic N-Ras signaling would have significant therapeutic impact for a number of different aggressive adult and pediatric cancers.