Small Molecule Inhibitors for the Oncogenic Protein Tyrosine Phosphatase SHP2

描述（由申请人提供）：可逆酪氨酸磷酸化，由蛋白酪氨酸激酶（PTKs）和蛋白酪氨酸磷酸酶（PTPs）的协调作用调节，对几乎所有基本细胞过程的信号事件至关重要。不出所料，扰乱PTK和PTP活性之间的平衡会导致酪氨酸磷酸化异常，导致包括癌症在内的许多人类疾病。该研究计划的长期目标是开发针对SHP2 （Src同源2结构域磷酸酶2）的小分子疗法，SHP2是在PTP超家族中发现的第一个真正的致癌基因。大多数受体酪氨酸激酶、细胞因子受体和整合素下游的Ras/ERK1/2活化都需要SHP2。此外，已知功能获得性SHP2突变可导致常染色体显性疾病Noonan综合征、多种形式的白血病和实体瘤。因此，SHP2是一个有吸引力的抗癌和抗白血病靶点。不幸的是，由于PTP活性位点的高正电荷性质，PTP是药物发现的极具挑战性的靶点。事实上，几乎所有现有的PTP抑制剂都含有带负电荷的非水解磷酸酪氨酸模拟物，并且膜通透性和细胞功效较差。为了克服生物利用度问题，我们开发了一种基于双环水杨酸药效团的突破性化学平台，该平台具有足够的极性，可以结合PTP活性位点，但仍然能够有效地穿过细胞膜。我们获得了一种基于吲哚水杨酸的SHP2抑制剂II-B08，它对SHP2的5M亲和力较低，对SHP2的偏好是一组哺乳动物ptp的几倍。此外，II-B08表现出出色的细胞活性。然而，II-B08的效力和选择性相对较弱，不足以用于化学生物学研究和治疗开发。为了进一步研究，我们已经获得了SHP2与II-B08复合物的三维结构，这揭示了可以用于获得具有增强性能的SHP2抑制剂的分子决定因素。在本提案中，我们将采用结构导向的重点文库合成策略来优化II-B08，使其成为高效和选择性的SHP2抑制剂。我们还将评估SHP2抑制剂的细胞功效、治疗潜力以及作用机制。多学科研究项目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射线晶体学等技术。该项目的成功完成将为开发针对血液恶性肿瘤和癌症患者的新型SHP2药物奠定坚实的基础。此外，有效的和选择性的SHP2抑制剂也将作为强有力的研究工具来描述SHP2在正常生理中的功能，并阐明SHP2诱发转化的潜在事件。

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.