Rab Geranylgeranylation: a Novel Therapeutic Target in Multiple Myeloma

描述(申请人提供)：多发性骨髓瘤(MM)的特征是恶性浆细胞的增殖，这些细胞分泌大量的单克隆蛋白(MP)。到目前为止，还没有针对MP分泌的治疗策略。Rab家族的小GTP酶在细胞内的囊泡运输中起着关键作用。通过干扰MP的分泌，导致MP在细胞内积聚，激活未折叠的蛋白反应通路(UPR)，破坏Rab蛋白的老年化，从而诱导MM细胞的凋亡。香叶基香叶基转移酶II(GGTase II)的有效抑制剂尚未开发出来，GGTase II是负责翻译后修饰Rab蛋白的酶。此外，关于个别RAB在管制MP贩运和 选择性干扰多发性骨髓瘤细胞Rab功能的作用。因此，我们提出了以下目标：1)开发新的GGTase II抑制剂；2)探讨RABS在调节MM细胞MP转运中的作用。新型GGTase II抑制剂的开发将涉及计算机辅助药物设计、化学合成和生物表征。试剂的设计和合成将包含三个部分：将与焦磷酸识别中心相互作用的非水解性极性头部基团，将与催化锌中心相互作用的锌结合基序，以及将与末端异戊二烯中心相互作用的类异戊二烯或类异戊二烯链。点击化学方法的使用将允许 产生了多个家族的新型代理人。将使用基于荧光的酶分析来确定这些化合物的抑制活性。其他研究将包括确定酶的特异性，评估在MM细胞中选择性抑制Rab geranylgeranyation的能力，评估细胞毒效应，并检查对MP运输的影响。为了探索单个RAB在MM细胞中的作用，我们将确定siRNA介导的特定RAB亚型沉默对关键细胞过程的影响，包括MP运输、UPR和细胞凋亡。这项工作将有助于更好地了解RABS在MM细胞中的作用，并开发用于治疗MM患者的新药物。

DESCRIPTION (provided by applicant): Multiple myeloma (MM) is characterized by the proliferation of malignant plasma cells which secrete large quantities of monoclonal protein (MP). As yet, no therapeutic strategies have been developed which target MP secretion. The Rab family of small GTPases plays key roles in intracellular vesicle trafficking. Agents which impair the geranylgeranylation of Rab proteins induce apoptosis of MM cells by disrupting MP secretion, resulting in accumulation of MP within the cells and activation of the unfolded protein response pathway (UPR). Potent inhibitors of geranylgeranyltransferase II (GGTase II), the enzyme responsible for post-translationally modifying Rab proteins, have yet to be developed. In addition, little is known regarding the role of individual Rabs in regulating MP trafficking and the effects of selectively disrupting Rab function in MM cells. The following aims are therefore proposed: 1) To develop novel inhibitors of GGTase II and 2) To explore the role of Rabs in regulating MP trafficking in MM cells. The development of novel inhibitors of GGTase II will involve computer-assisted drug design, chemical synthesis, and biological characterization. Agents will be designed and synthesized to contain three moieties: a non-hydrolysable polar head group which will interact with the pyrophosphate recognition site, a zinc-binding motif which will interact with the catalytic zinc site, and an isoprenoid or isoprenoid-like chain which will interact with the terminal isoprene site. The use of a click-chemistry approach will allow for the generation of multiple families of novel agents. A fluorescence-based enzyme assay will be used to determine the inhibitory activity of the compounds. Additional studies will involve determining enzyme specificity, assessing the ability to selectively inhibit Rab geranylgeranylation in MM cells, evaluating the cytotoxic effects, and examining the effects on MP trafficking. To explore the role of individual Rabs in MM cells, the effects of siRNA-mediated silencing of selected Rab isoforms on key cellular processes, including MP trafficking, the UPR, and apoptosis, will be determined. This work will lead to a better understanding of the role of Rabs in MM cells and to the development of novel agents with which to treat patients with MM.