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

 描述（由申请人提供）：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（硼替佐米）在治疗多发性骨髓瘤和套细胞淋巴瘤中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）。通过使用生物化学和遗传学方法，我们的实验室已经证明了HAUSP（一种去泛素化酶，也称为USP 7）在调节p53依赖性和p53非依赖性肿瘤抑制中的作用。值得注意的是，我们最近开发了针对HAUSP的特异性小分子抑制剂。拟议的研究旨在阐明HAUSP抑制剂在p53野生型和p53突变型肿瘤中的作用和机制。在目的1中，我们将通过使用HAUSP突变小鼠模型来检查HAUSP是否是抗肿瘤发生靶标。许多研究表明HAUSP可能是一个有价值的肿瘤治疗靶点。然而，这一概念尚未在任何遗传模型中得到证实。为此，我们将在经典的E-µ-Myc小鼠模型中研究HAUSP的失活是否通过激活p53功能来抑制肿瘤发生。在目的2中，我们研究HAUSP的作用，在调节p53非依赖性功能的神经母细胞瘤细胞通过调节N-myc的稳定性。在我们的初步研究中，我们已经证明HAUSP是一个真正的N-Myc去泛素化酶，N-myc蛋白的水平是由HAUSP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。在目的3中，我们将研究新发现的HAUSP抑制剂C5是否能够以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，我们已经鉴定了一种新的HAUSP抑制剂C5，并发现C5在HAUSP抑制中具有更强的活性（比已发表的先导化合物P5901好约100倍）。我们实验室和其他实验室的研究强烈表明，HAUSP活性在人肿瘤细胞中的靶向作用应该以p53依赖性和p53非依赖性的方式表现出抗肿瘤功效。我们将研究这种新化合物C5是否有可能抑制p53-wt和p53突变肿瘤中的癌症生长。

 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.