Disordered Regulation of Wnt/beta-catenin Signaling in MPNST Development and Maintenance

描述(申请人提供)：我们进行了两个大的筛选，以确定驱动MPNST形成或维持的基因：1)在人MPNST细胞系中的shRNA筛选，以及2)在MPNST的小鼠模型中的基于睡美人(SB)转座子的插入突变筛选。这两种研究方法都发现Wnt/β连环蛋白调节的通路是MPNST维持的关键介质。初步数据证实，Wnt/β连环蛋白通路是维持MPNST所必需的，并且可以用小分子靶向。值得注意的是，我们确定了在MPNST中工作的ββ连环蛋白的多种激活机制。我们的建议集中在这些方面。目的1是基于我们的数据，证明了β连环蛋白破坏复合体的遗传或药物激活降低了β连环蛋白水平，减少了靶基因的表达，并抑制了MPNST细胞的生存和增殖。目的2是基于数据显示，由于转录与上游EIF3E基因融合，一些MPNSTs异位表达WNT/β连环蛋白激活剂R-响应蛋白2(RSPO2)，这是我们最近在人类结直肠癌中发现的一种机制。目的3是基于揭示β连环蛋白靶基因PITX2在MPNST细胞生存中起关键作用的数据。我们的目标有两个：确定MPNST中β连环蛋白去调节的分子图景，并对在MPNST中干预WNT/β连环蛋白通路的关键靶点进行彻底的临床前评估，为在人类患者中进行有效的临床测试奠定基础。合作绩效机构建立了建立在互补技能和资源基础上的成功合作关系。大量的、正交的初步数据支持了这一建议的基本假设。

DESCRIPTION (provided by applicant): We carried out two large screens to identify genes driving MPNST formation or maintenance: 1) An shRNA screen in human MPNST cell lines, and 2) a Sleeping Beauty (SB) transposon- based insertional mutagenesis screen in a mouse model of MPNST. Both research approaches identified Wnt/β catenin-regulated pathways as critical mediators of MPNST maintenance. Preliminary data confirms that the Wnt/β catenin pathway is required for MPNST maintenance and can be targeted using small molecules. Remarkably, we identified multiple mechanisms of activation of β β catenin that operate in MPNST. Our proposal focuses on these. Aim 1 is based on our data demonstrating that genetic or pharmacological activation of the β catenin destruction complex reduce β catenin levels, reduce target gene expression, and inhibit cell survival and proliferation in MPNST. Aim 2 is based on data showing that some MPNSTs ectopically express a Wnt/β catenin activator R-spondin 2 (RSPO2) due to transcript fusion with the upstream EIF3E gene, a mechanism we recently identified in human colorectal cancer. Aim 3 is based on data revealing that the β catenin target gene PITX2 plays a critical role in MPNST cell survival. Our goals are two-fold: to define the molecular landscape of β catenin de-regulation in MPNST, and perform a thorough pre-clinical evaluation of critical targets for intervention in the Wnt/β catenin pathway in MPNST, setting the stage for effective clinical testing in human patients. The Co-PIs have established a successful collaborative relationship built on complementary skills and resources. Abundant and orthogonal preliminary data support the basic hypothesis of this proposal.