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

项目总结 靶向泛素-蛋白酶体系统对血液病的治疗有很大贡献 在过去的十五年里发生的癌症。尽管这些蛋白酶体靶向药物(如 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，用于治疗对当前疗法或难治性病人产生抵抗力的患者 案子。为了克服目前的挑战，许多组织已经开始瞄准 蛋白酶体。RPN-13，一种蛋白酶体调节颗粒上的泛素受体，一直是最多的 前景看好，因为它不是健康细胞中必需的蛋白酶体亚单位。我们的中心假设是 抑制蛋白酶体的调节功能，特别是RPN-13亚基，可以克服对BTZ的耐药性 机制，作为多发性骨髓瘤(MM)患者的替代疗法。使用电流缓蚀剂 RA190和KDT-11、RPN-13的抑制在体外和体内应用都对MM有毒性。自.以来 KDT-11已经被证明比RA190更具选择性，这项研究项目的长期目标是 开发效力更强、物理性能更好的RPN-13抑制剂，与KDT结合到同一表面- 并有选择地维持KDT-11‘S。该应用的目的是利用KDT-11作为化学探针 鉴定并探讨其与RPN-13及MM细胞株的作用机制。要完成这项工作 目的：(1)确定类肽探针KDT-11的结合部位 (2)观察KDT-11‘S对MM和BTZ耐药小鼠RPN-13及细胞凋亡途径的影响。 类肽，如KDT-11，一直被认为是潜在的治疗剂，但之前报道过类肽 由于低亲和力或非选择性，探针没有得到进一步的研究或优化。这项建议 在我们看来，这是创新的，因为我们计划将一个具有适度亲和力的选择性类肽探测器转变为 更多类铅支架，以开发更有效和更具药理作用的RPN-13抑制剂。这 由于KDT-11的S结合位点的发现和对KDT-11的评价，预计贡献将是重大的 它在抗BTZ多发性骨髓瘤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治疗的替代靶点有更多的了解。

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.