Targeting Deubiquitylating Enzymes in Multiple Myeloma

项目总结（见说明）： 正常的细胞内稳态通过蛋白质合成和降解的平衡调节来维持。泛素蛋白酶体系统（UPS）是通过蛋白酶体全酶、泛素连接酶和去泛素化酶（DUB）介导的非溶酶体细胞内蛋白降解途径。 UPS通路的失调与包括多发性骨髓瘤（MM）在内的各种人类疾病的发病机制有关;因此，在蛋白酶体或泛素化/去泛素化酶水平上的UPS通路抑制剂作为新的治疗策略提供了巨大的希望。在我们的第一个资助期，我们使用我们在BM环境中的MM细胞的体外和体内模型，在蛋白酶体水平上表征了MM中UPS的靶向。我们具体阐明了蛋白酶体抑制剂靶向肿瘤细胞、宿主肿瘤相互作用和BM微环境以克服耐药性的分子和细胞机制。我们的临床前和临床研究导致FDA批准硼替佐米用于复发性/难治性和新诊断的MM。虽然硼替佐米代表了一个重大进展，但并非所有患者都有反应，那些有反应的患者会复发。因此，我们最近的研究已经确定了对蛋白酶体抑制剂耐药的机制和克服它的策略。这项工作一方面导致了第二代蛋白酶体抑制剂，另一方面导致了科学的联合治疗，导致了多个正在进行的III期临床试验。我们最近的努力集中在UPS的另一个主要成分DUB的小分子抑制剂的发现和开发。我们的初步研究表明，与正常浆细胞相比，MM细胞中DUB USP 7的表达和活性增加，并且其抑制甚至在硼替佐米耐药的MM细胞中触发细胞凋亡。本提案旨在研究在蛋白酶体上游DUB水平抑制UPS可以抑制MM细胞生长并克服蛋白酶体抑制剂耐药性的假设。为了实现这些目标，我们将追求以下具体目标：具体目标1：表征去泛素化酶（DUB）在MM细胞生长、存活和耐药性中的作用。具体目标2：开发选择性DUB抑制剂，并确定其单独或与抗MM药物联合使用的体外作用机制。 具体目标3：在复发性难治性MM中进行DUB抑制剂的临床前体内研究和临床试验，无论是单独还是联合使用。这种在蛋白酶体或去泛素化酶水平上靶向MM中UPS通路的新范例，不仅有很大的希望改变MM的自然史，而且还可以作为其他癌症靶向治疗的模型。

PROJECT SUMMARY (See instructions): Normal cellular homeostasis is maintained by a balanced regulation of protein synthesis and degradation. The ubiquitin proteasome system (UPS) is a non-lysosomal intracellular protein degradation pathway mediated via proteasome holoenzymes, ubiquitin ligases, and deubiquitylating enzymes (DUBs). Deregulation of the UPS pathway is linked to the pathogenesis of various human diseases including multiple myeloma (MM); therefore, inhibitors of UPS pathways, either at the level of proteasomal or ubiquitylating/deubiquitylating enzymes, offers great promise as a novel therapeutic strategy. In our first funding period, we characterized targeting of UPS in MM at the level of the proteasome using our in vitro and in vivo models of the MM cell in the BM milieu. We specifically elucidated the molecular and cellular mechanisms whereby proteasome inhibitors target tumor cells, host tumor interactions, and the BM microenvironment to overcome drug resistance. Our preclinical and clinical studies led to the FDA approval of Bortezomib for relapsed/refractory and newly diagnosed MM. Although Bortezomib represents a major advance, not all patients respond, and those that respond relapse. Therefore our more recent studies have defined mechanisms of resistance to proteasome inhibitors and strategies to overcome it. This work has led to second-generation proteasome inhibitors on the one hand, and scientifically-informed combination therapies on the other, leading to multiple ongoing phase III clinical trials. Our recent efforts have focused on discovery and development of small molecule inhibitors of another major component of UPS, DUBs. Our Preliminary Studies show increased expression and activity of the DUB USP7 in MM cells versus normal plasma cells, and that its inhibition triggers apoptosis even in Bortezomib resistant MM cells. The current proposal aims to investigate the hypothesis that inhibition of the UPS at the level of DUBs, upstream of the proteasome, can inhibit MM cell growth and overcome proteasome inhibitor resistance. To achieve these goals, we will pursue the following Specific Aims: Specific Aim 1: To characterize the role of deubiquitylating enzymes (DUBs) in MM cell growth, survival, and drug resistance. Specific Aim 2: To develop selective DUB inhibitors and define their in vitro mechanism of action, either alone or in combination with anti-MM agents. Specific Aim 3: To conduct preclinical in vivo studies and clinical trials of DUB inhibitors, either alone or in combination, in relapsed refractory MM. This new paradigm to target UPS pathways in MM, either at the level of proteasome or deubiquitylating enzymes, has great promise not only to change the natural history of MM, but also to serve as a model for targeted therapeutics in other cancers.