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

描述（由申请人提供）：我们进行了两个大型筛选来鉴定驱动MPNST形成或维持的基因：1)在人类MPNST细胞系中进行shRNA筛选，以及2)在小鼠MPNST模型中进行基于睡美人（SB）转座子的插入突变筛选。两种研究方法都确定了Wnt/ atenin调节通路是MPNST维持的关键介质。初步数据证实Wnt/ atenin通路是MPNST维持所必需的，并且可以使用小分子靶向。值得注意的是，我们发现了在MPNST中起作用的- atenin激活的多种机制。我们的建议集中在这些方面。Aim 1是基于我们的数据表明，基因或药物激活的- atenin破坏复合体降低- atenin水平，降低靶基因表达，抑制MPNST细胞存活和增殖。Aim 2基于数据显示，一些MPNSTs由于与上游EIF3E基因的转录融合而异位表达Wnt/ α - atenin激活剂R-spondin 2 (RSPO2)，这是我们最近在人类结直肠癌中发现的一种机制。Aim 3是基于揭示- atenin靶基因PITX2在MPNST细胞存活中起关键作用的数据。我们的目标有两个：确定MPNST中- atenin去调控的分子格局，并对MPNST中Wnt/ - atenin通路的干预关键靶点进行全面的临床前评估，为在人类患者中进行有效的临床试验奠定基础。在互补的技能和资源的基础上，合作项目已经建立了成功的合作关系。大量正交的初步数据支持了本文的基本假设。

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/�atenin-regulated pathways as critical mediators of MPNST maintenance. Preliminary data confirms that the Wnt/�atenin pathway is required for MPNST maintenance and can be targeted using small molecules. Remarkably, we identified multiple mechanisms of activation of �atenin that operate in MPNST. Our proposal focuses on these. Aim 1 is based on our data demonstrating that genetic or pharmacological activation of the �atenin destruction complex reduce �atenin 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/�atenin 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 �atenin target gene PITX2 plays a critical role in MPNST cell survival. Our goals are two-fold: to define the molecular landscape of �atenin de- regulation in MPNST, and perform a thorough pre-clinical evaluation of critical targets for intervention in the Wnt/�atenin 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.