Investigating the Interaction of a Selective Peptoid Probe and Rpn-13, A Non-Essential Ubiquitin Receptor of the Proteasome

项目摘要 靶向泛素-蛋白酶体系统极大地促进了血液病的治疗。 癌症在过去的15年里尽管这些蛋白酶体靶向药物（如 硼替佐米，Btz），其抑制蛋白酶体的催化功能、最终的耐药性和脱靶毒性 对替代疗法的需求，以治疗对当前治疗产生耐药性的患者或难治性 例为了克服当前的挑战，许多研究小组已经开始针对基因组中的调节亚基， 蛋白酶体Rpn-13是蛋白酶体调节颗粒上的一种泛素受体， 因为它不是健康细胞中必需的蛋白酶体亚基。我们的核心假设是， 抑制蛋白酶体的调节功能，特别是Rpn-13亚基，可以克服Btz抗性。 机制，作为多发性骨髓瘤（MM）患者的替代疗法。使用当前的抑制剂 在体外和体内应用中观察到RA 190和KDT-11、Rpn-13抑制对MM具有毒性。以来 KDT-11已被证明比RA190更具选择性，该研究项目的长期目标是 开发具有改进的效力和物理特性的Rpn-13抑制剂，其与KDT结合在相同的表面上， 11和保持KDT-11的选择性。本申请的目的是利用KDT-11作为化学探针 表征并探索其与Rpn-13和MM细胞系的作用机制。完成这个 目的：（1）确定类肽探针KDT-11的结合位点 （2）评价KDT-11对MM和Btz耐药MM中Rpn-13和凋亡途径的影响。 类肽，如KDT-11，已被认为是潜在的治疗剂，但以前报道的类肽， 由于低亲和力或非选择性，探针没有被进一步研究或优化。这项建议 在我们看来，这是创新的，因为我们计划将具有适度亲和力的选择性类肽探针转变为 更多的铅样支架，以开发更有效的和药理学上适用的Rpn-13抑制剂。这 由于KDT-11的结合位点的发现和对KDT-11结合位点的评估， 它在Btz耐药MM中的作用机制将允许优化唯一报道的可逆选择性 Rpn-13的抑制剂，这将导致对MM治疗的替代靶点的更好理解。

PROJECT SUMMARY Targeting the ubiquitin-proteasome system has greatly contributed to the treatment of hematological cancers over the past fifteen years. Despite the success of these proteasome-targeted drugs (such as bortezomib, Btz) that inhibit the proteasome’s catalytic function, eventual drug resistance and off-target toxicities demand for alternative therapies to treat patients that become resistant to current treatments or for refractory cases. To overcome the current challenges, many groups have begun targeting the regulatory subunits of the proteasome. Rpn-13, a ubiquitin receptor on the proteasome’s regulatory particle, has been one of the most promising targets as it is not an essential proteasome subunit in healthy cells. Our central hypothesis is that inhibition of the proteasome’s regulatory function, specifically the Rpn-13 subunit, can overcome Btz-resistant mechanisms, working as an alternative therapy for multiple myeloma (MM) patients. With current inhibitors RA190 and KDT-11, Rpn-13 inhibition is observed to be toxic to MM in in vitro and in vivo applications. Since KDT-11 has been shown to be more selective than RA190, the long-term goal of this research project is to develop Rpn-13 inhibitors with improved potency and physical properties that bind to the same surface as KDT- 11 and maintain KDT-11’s selectively. The objective for this application is to utilize KDT-11 as a chemical probe to characterize and to explore its mechanism of action with Rpn-13 and in MM cell lines. To complete this objective, we propose the following specific aims: (1) To determine the binding site of the peptoid probe KDT-11 on Rpn-13, and (2) to evaluate KDT-11’s effect on Rpn-13 and apoptotic pathways in MM and Btz-resistant MM. Peptoids, such as KDT-11, have been considered potential therapeutic agents but previously reported peptoid probes have not been further investigated or optimized either due to low-affinity or non-selectivity. This proposal is innovative, in our opinion, because we plan to transition a selective peptoid probe with modest affinity to a more lead-like scaffold to develop more potent and pharmacologically-amenable Rpn-13 inhibitors. This contribution is expected to be significant because the discovery of KDT-11’s binding site and the evaluation of its mechanism of action in Btz-resistant MM would allow for optimization of the only reported reversible selective inhibitor for Rpn-13, which would lead to a greater understanding for alternative targets for MM treatment.