Ubc9 as a novel target for cancer therapy

描述（由申请人提供）： SUMO（small ubiquitin-related modifier，小泛素相关修饰物）缀合或SUMO化参与调节转录因子的活性，介导蛋白质的核转位或亚核结构的形成，以及蛋白质的稳定性，从而调节几种重要的细胞活性。由于Ubc 9是SUMO化所必需的唯一E2缀合酶，因此认为其通过调节SUMO化在这些方面发挥核心作用，最终影响细胞生长和癌症发展。我们的初步研究表明，Ubc 9的表达改变与人类恶性肿瘤有关。此外，小鼠异种移植模型的实验表明Ubc 9在肿瘤发生中起作用。我们的长期目标是更好地了解Ubc 9介导的肿瘤发生的基础，并开发基于Ubc 9的癌症治疗药物。具体目标是：1）通过短的双链干扰RNA（siRNA）和可能阻断Ubc 9与SUMO相互作用的小化合物靶向Ubc 9。这些实验将使我们不仅能够进一步证明Ubc 9在肿瘤发生中的作用，而且还能够识别潜在的治疗药物。2)确定Ubc 9-siRNA在小鼠异种移植模型中的治疗功能。因此，将合成的Ubc 9-siRNA或基于载体的Ubc 9-siRNA递送到荷瘤动物中以确定它们对肿瘤生长的影响。3)剖析Ubc 9介导的肿瘤发生的分子机制。来自过表达野生型Ubc 9或显性阴性Ubc 9或Ubc 9-siRNA的细胞的肿瘤将用于通过微阵列技术进行基因谱分析以鉴定基因 或与Ubc 9相关的通路。4）分析Ubc 9调控。我们的初步研究表明，紫外线照射，一个众所周知的肿瘤促进剂，诱导Ubc 9的表达，这表明Ubc 9在紫外线诱导的致癌作用。因此，将进行实验以研究Ubc 9调控的潜在机制，包括Ubc 9启动子活性、Ubc 9 mRNA和蛋白的稳定性以及影响其表达的表观遗传因素。总之，拟议的工作将提供有关Ubc 9作为新型治疗靶点的有用信息，以及对Ubc 9介导的肿瘤发生的分子机制的新见解。因此，我们将能够开发有价值的基于Ubc 9的抗癌剂。

DESCRIPTION (provided by applicant): SUMO (small ubiquitin-related modifier) conjugation or sumoylation has been implicated in regulating activity of transcription factors, mediating nuclear translocation of proteins or formation of subnuclear structures, and protein stability, thus modulating several critical cellular activities. Because Ubc9 is a sole E2 conjugating enzyme essential for sumoylation, it is believed to play a central role in these aspects through regulation of sumoylation, ultimately impacting cell growth and cancer development. Our preliminary studies have revealed that altered expression of Ubc9 is associated with human malignancy. Furthermore, experiments with the mouse xenograft model have suggested that Ubc9 plays a role in tumorigenesis. Our long-term objectives are to better understand the basis for Ubc9-mediated tumorigenesis and to develop Ubc9-based therapeutic agents for cancer treatment. Specific aims are to: 1) Target Ubc9 by a short double-stranded interfering RNA (siRNA) and by small chemical compounds that potentially block the interaction of Ubc9 with SUMO. These experiments will enable us not only to further demonstrate the role for Ubc9 in tumorigenesis, but also identify potential therapeutic agents. 2) Determine the therapeutic functions of Ubc9-siRNA in the mouse xenograft model. Thus, the synthetic Ubc9-siRNA or the vector-based Ubc9-siRNA will be delivered into tumor-bearing animals to determine their effect on the tumor growth. 3) Dissect molecular mechanisms of Ubc9-mediated tumorigenesis. Tumors derived from the cells overexpressing wild type Ubc9 or dominant negative Ubc9 or Ubc9-siRNA will be used for gene profiling by the microarray technology to identify genes or pathways associated with Ubc9.4) Analyze Ubc9 regulation. Our preliminary studies have indicated that UV irradiation, a well-known tumor promoter, induces Ubc9 expression, suggesting a role for Ubc9 in UV-induced carcinogenesis. Thus, experiments will be carried out to investigate the underlying mechanism of Ubc9 regulation, including Ubc9 promoter activity, stability of Ubc9 mRNA and protein, and epigenetic factors that affect its expression. Together, the proposed work will provide useful information on Ubc9 as a novel therapeutic target as well as new insight into the molecular mechanism of Ubc9-mediated tumorigenesis. As a result, we will be able to develop valuable Ubc9-based anticancer agents