Small Molecule Inhibitors for the Oncogenic Protein Tyrosine Phosphatase SHP2

描述（由申请人提供）：由蛋白酪氨酸激酶（PTK）和蛋白酪氨酸磷酸酶（PTPs）的协调作用调节的可逆酪氨酸磷酸化对几乎所有基本细胞过程的信号传导事件至关重要。毫不奇怪，PTK和PTP活性之间平衡的紊乱导致异常酪氨酸磷酸化，引起许多人类疾病，包括癌症。拟议研究计划的长期目标是开发靶向SHP 2（含Src同源2结构域的磷酸酶2）的小分子疗法，SHP 2是PTP超家族中鉴定的第一个真正的致癌基因。SHP 2是大多数受体酪氨酸激酶、细胞因子受体和整联蛋白下游的Ras/ERK 1/2活化所必需的。此外，已知功能获得性SHP 2突变会导致常染色体显性遗传疾病努南综合征、多种形式的白血病和实体瘤。因此，SHP 2代表了一个有吸引力的抗癌和抗白血病靶点。不幸的是，PTP是非常具有挑战性的药物发现的目标，主要是由于PTP活性位点的高度正电荷的性质。事实上，几乎所有现有的PTP抑制剂都含有带负电荷的不可水解的磷酸酪氨酸模拟物，并且具有差的膜渗透性和细胞功效。为了克服生物利用度问题，我们已经开发了一种突破性的化学平台，该平台基于双环水杨酸药效团，其具有足够的极性以结合PTP活性位点，但仍然能够有效地穿过细胞膜。我们已经获得了基于吲哚水杨酸的SHP 2抑制剂II-B 08，其对SHP 2具有低的5 M亲和力，并且对SHP 2的偏好是一组哺乳动物PTP的几倍。此外，II-B 08表现出出色的细胞活性。然而，II-B 08显示的效力和选择性相对适中，不足以进行化学生物学研究和治疗开发。为了向前推进，我们已经获得了与II-B 08复合的SHP 2的三维结构，这揭示了可用于获得具有增强特性的SHP 2抑制剂的分子决定因素。在这项提案中，我们将应用结构指导的聚焦文库合成策略来优化II-B 08成为高效和选择性的SHP 2抑制剂。我们还将评估细胞功效、治疗潜力以及SHP 2抑制剂的作用机制。多学科研究计划利用合成和组合化学，高通量筛选，酶动力学，细胞生物学，信号转导，定点诱变和X射线晶体学技术。该项目的成功完成将为开发针对SHP 2的新型药物用于血液恶性肿瘤和癌症患者奠定坚实的基础。此外，有效的和选择性的SHP 2抑制剂也将作为强大的研究工具，以描绘SHP 2在正常生理学中的功能，并阐明SHP 2诱发转化的事件。 公共卫生相关性：SHP 2蛋白酪氨酸磷酸酶是导致常染色体显性遗传疾病努南综合征、多种形式的白血病和实体瘤的致癌基因，因此代表抗癌和抗白血病治疗的有吸引力的靶标。本申请的目的是开发有效和选择性的小分子SHP 2抑制剂，并评估其用作抗血液恶性肿瘤和癌症药物的潜力。

DESCRIPTION (provided by applicant): Reversible tyrosine phosphorylation, regulated by the coordinated actions of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), is of critical importance to signaling events that underlie virtually all essential cellular processes. Not surprisingly, disturbance of the balance between PTK and PTP activity leads to aberrant tyrosine phosphorylation, causing many human diseases, including cancer. The long-term objective of the proposed research program is to develop small molecule therapeutics targeting SHP2 (Src homology 2 domain-containing phosphatase 2), which is the first bona fide oncogene identified in the PTP superfamily. SHP2 is required for Ras/ERK1/2 activation downstream of most receptor tyrosine kinases, cytokine receptors, and integrins. In addition, gain-of-function SHP2 mutations are known to cause the autosomal dominant disorder Noonan Syndrome, multiple forms of leukemia and solid tumors. Consequently, SHP2 represents an attractive anti-cancer and anti-leukemia target. Unfortunately, PTPs are exceptionally challenging targets for drug discovery, due primarily to the highly positively charged nature of the PTP active site. Indeed, almost all existing PTP inhibitors contain negatively charged nonhydrolyzable phosphotyrosine mimetics, and suffer poor membrane permeability and cellular efficacy. In order to overcome the bioavailability issue, we have developed a breakthrough chemistry platform based on bicyclic salicylic acid pharmacophores that are sufficiently polar to bind the PTP active site, yet remain capable of efficiently crossing cell membranes. We have acquired an indole salicylic acid based SHP2 inhibitor II-B08, with a low 5M affinity for SHP2 and several fold preference for SHP2 over a panel of mammalian PTPs. Moreover, II-B08 exhibits outstanding cellular activity. However, the potency and selectivity displayed by II-B08 are relatively modest, and are inadequate for chemical biological investigation and therapeutic development. To move forward, we have obtained a three-dimensional structure of SHP2 in complex with II-B08, which reveals molecular determinants that can be exploited for the acquisition of SHP2 inhibitors with enhanced properties. In this proposal, we will apply a structure-guided focused library synthesis strategy to optimize II-B08 into highly potent and selective SHP2 inhibitors. We will also evaluate the cellular efficacy, therapeutic potential, as well as mechanism of action of the SHP2 inhibitory agents. The multidisciplinary research program utilizes techniques in synthetic and combinatorial chemistry, high-throughput screening, enzyme kinetics, cell biology, signal transduction, site-directed mutagenesis, and X-ray crystallography. Successful completion of this project will create a solid foundation upon which novel agents targeted to SHP2 can be developed for individuals with hematologic malignancies and cancer. In addition, potent and selective SHP2 inhibitors will also serve as powerful research tools to delineate the function of SHP2 in normal physiology and to elucidate the events underlying SHP2-evoked transformation. PUBLIC HEALTH RELEVANCE: The SHP2 protein tyrosine phosphatase is an oncogene responsible for the autosomal dominant disorder Noonan Syndrome, multiple forms of leukemia and solid tumors and thus represents an attractive target for anti-cancer and anti-leukemia therapy. The goals of this application are to develop potent and selective small molecule SHP2 inhibitors and to evaluate their potential to be used as anti-hematologic malignancies and cancer agents.