Novel lysine deacetylase 6 Hsp domain inhibitors against AML

描述（由申请人提供）：急性髓性白血病（AML）是最常见和侵袭性的急性白血病之一，每年影响30,000人。5年以上的生存率仍然保持在10-30%左右，这在很大程度上取决于患者耐受细胞毒性化疗的能力，细胞毒性化疗抑制了急需的造血功能。当前治疗方式的局限性表明，需要针对AML中相关生物学靶点的创新疗法来改善临床结果。AML是一种异质性疾病；最近的研究发现，在FLT-3、c-Kit和Ras以及STAT5和嵌合体MLL等组成型活性转录因子中，一组激活激酶突变与疾病结局相关。治疗AML的主要挑战之一是开发能够影响多种促进AML增殖和生存的生物学途径的疗法。组蛋白去乙酰化酶同工酶6 （HDAC6）在AML患者中过度表达，并被假设通过调节热休克蛋白功能在维持致癌信号传导中发挥关键作用，而热休克蛋白功能对AML的发病和生存至关重要。在转化的细胞和体内，恶性细胞转化也需要HDAC6。此外，HDAC6敲除小鼠已被证明能够抵抗诱变原诱导的肿瘤并正常发育，这进一步强调了HDAC6作为AML耐受性更好、毒性更低的治疗靶点的潜力。我们已经发现了新的HDAC6-Hsp结构域抑制剂，它优先抑制HDAC6-Hsp低乙酰化结构域。Hsp90乙酰化，不像典型的羟酸类HDAC6抑制剂，tubastatin A和Tubacin。我们的主要假设是HDAC6-Hsp结构域的活性通过维持多种热休克蛋白的正常功能来促进AML的增殖和存活。选择性抑制HDAC6-Hsp结构域使多种Hsp活性失活，减弱异常的AML致癌信号，促进AML细胞凋亡。本研究拟采用多方面和创新的方法来开发新的HDAC6-Hsp结构域抑制剂，并研究HDAC6在AML中调控Hsp活性和细胞凋亡启动中的作用。在Aim 1中，我们将通过系统发育文库合成来完善我们的HDAC6-Hsp抑制剂，以表征HDAC6-Hsp结构域的结构活性关系。在Aim 2中，我们将研究HDAC6- hsp通路轴，研究HDAC6依赖性Hsp70调控，以及Hsp70乙酰化在凋亡形成中的作用。最后，我们将使用生理相关的弥散性AML异种移植模型在体内检查我们的HDAC6-Hsp去乙酰化结构域抑制剂。我们将确定我们的HDAC6先导抑制剂候选药物对AML的疗效，对先导抑制剂候选药物进行药代动力学和动力学研究，并验证抑制剂在体内影响生物标志物的能力。

DESCRIPTION (provided by applicant): Acute myelogenous leukemia (AML) is one of the most common and aggressive forms of acute leukemia affecting 30,000 people per year. Greater than 5 year survival rate still remains around 10-30%, and this depends greatly on the patient's ability to tolerate the combination of cytotoxic chemotherapies, which suppresses much needed haemopoiesis. The limits of current treatment modalities indicate a need for innovative therapies directed against relevant biological targets in AML to improve the clinical outcome. AML is a heterogeneous disease; recent studies have identified a set of activating kinase mutations in FLT-3, c-Kit, and Ras and constitutively active transcription factors such as STAT5 and chimera MLL relevant to disease outcome. One of the major challenges in treating AML is developing therapies that are capable of affecting multiple biological pathways promoting AML proliferation and survival. Histone deacetylase isozyme 6 (HDAC6) is over-expressed in AML patients and is hypothesized to play a key role in maintaining oncogenic signaling through the regulation of heat-shock protein functions that are critical for AML pathogenesis and survival. HDAC6 is also required for malignant cell transformation both in transformed cells and in vivo. Moreover, HDAC6 knock-out mice have been shown to resist mutagen induced tumors and develop normally, which further underscore the potential of HDAC6 as a better tolerated and less toxic therapeutic target for AML. We have identified novel HDAC6-Hsp domain inhibitors, which preferentially inhibit the HDAC6-Hsp deacetylation domain at low ?M concentration and induce Hsp90 acetylation, unlike the canonical hydroxamate HDAC6 inhibitors, tubastatin A and Tubacin. Our overarching hypothesis is that HDAC6-Hsp domain activity promotes AML proliferation and survival by maintaining proper function of multiple heat-shock proteins. Selective HDAC6-Hsp domain inhibition deactivates multiple Hsp activities, attenuates aberrant AML oncogenic signaling, and promotes AML apoptosis. This proposal intends to use multifaceted and innovative approaches to develop novel HDAC6-Hsp domain inhibitors and to investigate the role that HDAC6 plays in the regulation of Hsp activities and apoptosis initiation in AML. In Aim 1, we will refine our HDAC6-Hsp inhibitors through a phylogenetic library synthesis in order to characterize the structure activity relationship of the HDAC6-Hsp domain. In Aim 2, we will investigate the HDAC6-Hsp pathway axis, study HDAC6 dependent Hsp70 regulation, and the roles of Hsp70 acetylation play in apoptosome formation. Finally, we will examine our HDAC6-Hsp deacetylation domain inhibitors in vivo using a physiologically relevant disseminated AML xenograft model. We will determine the efficacy of our lead HDAC6 inhibitor candidates against AML, performing pharmacokinetic and dynamic studies on lead inhibitor candidates, and validate the inhibitor's ability to influence biomarkers in vivo.