HAUSP inhibitors in p53-wild type and p53-mutant tumors

 描述(申请人提供)：蛋白质泛素化和去泛素化与许多人类癌症的发病机制有关。蛋白酶体抑制剂VELCADE(Bortezomib)治疗多发性骨髓瘤和套细胞淋巴瘤的有效性确立了泛素-蛋白酶体系统作为有效的抗癌治疗靶点(Cohen和Tcherpakov，2010)。通过使用生化和遗传方法，我们的实验室已经证明了Hausp(一种去泛素酶，也称为USP7)在调节P53依赖和P53非依赖的肿瘤抑制中的作用。值得注意的是，我们最近开发了针对Hausp的特定小分子抑制剂。这些研究旨在阐明Hausp抑制剂在p53野生型和突变型肿瘤中的作用和机制。在目标1中，我们将通过使用Hausp突变小鼠模型来检验Hausp是否是抗肿瘤发生的靶点。许多研究表明，Hausp可能是癌症治疗的一个有价值的靶点。然而，这一概念还没有在任何遗传模型中得到证实。为此，我们将在经典的E-µ-Myc小鼠模型中检测Hausp的失活是否通过激活体内的P53功能来抑制肿瘤的发生。在目标2中，我们通过调节N-myc的稳定性来研究Hausp在神经母细胞瘤细胞中调节P53非依赖性功能中的作用。在我们的初步研究中，我们已经证明Hausp是N-Myc的一种真正的脱泛素酶，并且N-myc蛋白的水平受到Hausp的严格控制。众所周知，N-myc在神经母细胞瘤中扩增或过表达。为了进一步阐明Hausp/N-myc相互作用的生理学相关性，我们将研究Hausp在调节N-myc介导的人神经母细胞瘤癌细胞功能中的作用。在目标3中，我们将检测新发现的Hausp抑制剂C5是否能够通过P53依赖和P53非依赖的方式抑制肿瘤生长。在我们的初步研究中，我们发现了一种新的Hausp抑制剂C5，并发现C5在Hausp抑制方面具有更强的活性(大约是已发表的先导化合物P5901的100倍)。我们实验室和其他实验室的研究有力地表明，在人类肿瘤细胞中靶向Hausp活性应该以P53依赖和P53非依赖的方式显示出抗肿瘤效果。我们将检查这种新化合物C5是否具有潜在地抑制P53-wt和P53突变肿瘤中的癌症生长的能力。

 DESCRIPTION (provided by applicant): Protein ubiquitination and deubiquitination have been implicated in the pathogenesis of many human cancers. The effectiveness of the proteasome inhibitor Velcade (bortezomib) in the treatment of multiple myeloma and mantle cell lymphoma establishes the ubiquitin-proteasome system as a valid anti-cancer therapeutic target (Cohen and Tcherpakov, 2010). By using both biochemical and genetic approaches, our lab has demonstrated the roles of HAUSP (a deubiquitinase, also called USP7) in regulating both p53-dependent, and p53-independent tumor suppression. Notably, we have recently developed specific small molecule inhibitors for HAUSP. The proposed studies aim to elucidate the effects and mechanisms of HAUSP inhibitors in both p53-wild type and p53 mutant tumors. In Aim 1, we will examine whether HAUSP is an anti- tumorigenesis target by using HAUSP mutant mouse models. A number studies suggest that HAUSP may be a valuable target in cancer therapy. Nevertheless, this notion has not been demonstrated in any genetic models. In this aim, we will examine whether inactivation of HAUSP inhibits tumorigenesis by activating p53 function in vivo in the classic E-µ-Myc mouse model. In Aim 2, we investigate the role of HAUSP in regulating p53-independent functions in neuroblastoma cells by modulating N-myc stability. In our preliminary studies, we have demonstrated that HAUSP is a bona fide deubiquitinase of N-Myc and that the levels of N-myc protein are tightly controlled by HAUSP. It is well known that N-myc is amplified/or overexpressed in neuroblastomas. To further elucidate the physiological relevance of the HAUSP/N-myc interaction, we will examine the role of HAUSP in regulating N-myc mediated functions in human neuroblastoma cancer cells.In Aim 3, we will examine whether C5, a newly identified HAUSP inhibitor is able to suppress tumor growth in both p53-dependent and p53-independent manners. In our preliminary studies, we have identified a novel HAUSP inhibitor C5 and found that C5 has a much stronger activity (about 100X better than the published leading compound P5901) in HAUSP inhibition. The studies from our lab and others strongly suggest that the targeting of HAUSP activity in human tumors cells should exhibit antitumor efficacy in both p53-dependent and p53-independent manners. We will examine whether this new compound C5 potentially has the abilities to suppress cancer growth in both p53-wt and p53 mutant tumors.